Abstracts From the 50th Annual Meeting of the Society for Neuroscience in Anesthesiology and Critical Care, September 8-11, 2022 : Journal of Neurosurgical Anesthesiology

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Abstracts From the 50th Annual Meeting of the Society for Neuroscience in Anesthesiology and Critical Care, September 8-11, 2022

Journal of Neurosurgical Anesthesiology: October 2022 - Volume 34 - Issue 4 - p 451-508
doi: 10.1097/ANA.0000000000000863
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[SNACC-1] A Brush with Danger: An Emergent Traumatic Transoral Intradural Toothbrush Perforation with Superior Cervical Laminectomy and Dural Repair

Kiel A, Brown M, Abcejo, A. Mayo Clinic, Rochester, Minnesota, United States.

A previously healthy 40-year-old male was transferred by flight emergency medical services from an outside hospital after falling while brushing his teeth with an electric toothbrush while acutely alcohol intoxicated. The toothbrush impaled transorally into posterior tissue. After falling, the patient was able to remove the handle but unable to remove the toothbrush head from his mouth. Apart from limited speech determined to be due to pain, he had a normal neurological exam on presentation and patent airway. Computerized tomography (CT) scan revealed the toothbrush head extending from the left side of the oral cavity through the left C2-3 foramen with the bristles causing spinal cord and thecal sac deviation. Additional pertinent findings included significant pharyngeal and prevertebral soft tissue edema, left anterior C2 displacement, and posttraumatic gas within the spinal canal and along the cerebellar vermis. Anesthesiology, Neurosurgery, and Otolaryngology established the initial plan to perform an awake tracheostomy followed by C2-3 laminectomy, duraplasty, and removal of the toothbrush head by posterior approach. Awake tracheostomy was performed with moderate sedation via dexmedetomidine and fentanyl, enhanced with a blood ethanol level of 231 mg/dL. Extreme care was taken to maintain oxygenation and minimize neck movement during awake tracheostomy. Following awake tracheostomy, general anesthesia was induced and maintained with a total intravenous anesthetic with propofol and remifentanil. The procedure was completed successfully, however, the following morning he had a precipitous neurologic decline and required emergent C1 laminectomy, suboccipital decompression, removal of necrotic cerebellar tissue, and placement of an external ventricular drain (EVD). He was discharged to inpatient rehabilitation 19 days later and discharged home after an additional 12 days. At time of discharge, he had slight left sided cerebellar symptoms including intermittent dizziness when walking, difficulty with balance in some situations, and finger to nose dysmetria. Except for generalized deconditioning, he was back to his baseline functional status. This case highlights strategies used to obtain a protected airway in the context of complex, anatomically undifferentiated pharyngeal and neck trauma.

[SNACC-2] A case report: Rapid decrease of cerebral oxygen saturation after the cervical branch reconstruction of Total Aortic Arch Replacement indicated a true lumen collapse of the right carotid artery

Miura S*, Yoshitani K, Ohnishi Y. Ibaraki Prefectual Central Hospital, Ibaraki Cancer Center, Matsudo, Chiba, Japan*. National Cerebral & Cardiovascular Center, Suita, Osaka, Japan

Malperfusion of the carotid artery in acute aortic dissection is a severe complication and worsens prognosis. Intraoperatively, the dissection may extend into the intact carotid artery preoperatively, causing a sudden decrease in cerebral perfusion pressure. We present the case that regional cerebral oxygen saturation (rSO2) indicated the acute occlusion of the carotid artery due to the collapse of the true lumen. The rSO2 successfully recovered after re-anastomosis of the carotid artery.

Case: A 78-year-old man with Debakey I acute aortic dissection underwent emergent Total Aortic Arch Replacement. Thoracic enhanced computed tomography showed that the lesion of aortic dissection was limited to the aortic arch. Neuro monitoring included rSO2 measured by O3 and Sedline (Mashimo, Irvine, CA, USA). After heparin administration for cardiopulmonary bypass (CPB), rSO2 suddenly decreased from 60 to 20% on the right side. Transesophageal echocardiography demonstrated that aortic dissection extended to the descending aorta and the carotid artery. After starting the cardiopulmonary bypass, body temperature was cooled to 18 Celsius for brain protection. The left and right carotid, and the left subclavian artery were reconstructed during the selective cerebra perfusion, in which rSO2 was around 65%. After coming off the CPB, rSO2 suddenly decreased to 30% on the right side. Carotid artery sonography indicated the collapse of the right carotid artery (Figure 1 and 2). We suspected reperfusion from the reentry of the distal side compressed the true lumen of the proximal side of the carotid artery. The surgeon decided to perfume re-anastomosis of the left carotid artery. After the re-anastomosis of the right carotid artery at the distal side, rSO2 increased to 60%.

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FIGURE 1:
The blood flow of the right carotid artery by carotid ultrasoundgraphy.
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FIGURE 2:
The blood flow of the right carotid artery after comming off cardiopulmonary bypass.

Conclusion: rSO2 successfully indicated a true lumen collapse of the right carotid artery due to reperfusion from the reentry of the distal side. rSO2 monitoring is helpful and would be recommended during acute aortic dissection.

[SNACC-3] A comparison of regional cerebral oxygen saturation using near-infrared spectroscopy (NIRS) of NIRO-200NX and O3 in patients with pulmonary endarterectomy

Masuda S*, Yoshitani K*, Tsukinaga K, Nakano Y*. National Cerebral & Cardiovascular Center, Suita, Osaka, Japan*. Iwate Medical University, Morioka, Iwate, Japan

Background: Several devices are now available for measuring regional cerebral oxygen saturation using near-infrared spectroscopy. There were wide varieties in regional cerebral oxygen saturation among several devices (1). Among devices, NIRO-200NXⓇ (Hamamatsu Photonics, Hamamatsu, Japan) has had small contamination of the skull and cerebrospinal fluid layer compared with INVOS (2). Also, O3Ⓡ (Masimo, Neuchatel, Switzerland) had received Food Drug Administration (FDA) approval for use on infant and neonatal patients (<10 kg) and has been used widely in addition in adult patients. However, no studies have investigated the difference between these two devices during deep hypothermic circulatory cardiac arrest to our best knowledge. Therefore, we compared the cerebral oxygen saturation of NIRO-200 NX (TOI) and O3(rSO2).

Methods: This study was approved by the Ethics Committee of our institute. We compared TOI with rSO2 in patients with chronic thromboembolic pulmonary hypertension (CTEPH) undergoing pulmonary endarterectomy (PEA), which requires deep hypothermic circulatory arrest (DHCA) to prevent the backflow of blood from the pulmonary artery several times for approximately 20 minutes. Both the NIRO-200NX sensor and O3 sensor were attached to the forehead to measure cerebral oxygen saturation simultaneously. We recorded the TOI and rSO2 during DHCA and compared whether NIRO and O3 changed similarly, because the value of TOI and rSO2 decreased dramatically in each DHCA typically.

Results: Twenty-nine patients were enrolled in this study. There were 144 times of DHCA in this study. We obtained bilateral cerebral oxygen saturation (CH1: left frontal side, CH2: right frontal side) at 288 points. The values of rSO2 were compared with TOI at pre-DHCA, DHCA, and the end of reperfusion. The values of rSO2 decreased during DHCA and improved in reperfusion phase in both devices. The time course of change of TOI and rSO2 was shown in Figure 1. Further %change of rSO2 and TOI were in Figure 2.

We used mixed linear regression model to examine the difference between NIRO and O3. There were significant interactions between the rSO2 and TOI value in DHCA (P<0.001) (Figure 1) Also, there was a significant interaction between the % change of rSO2 and TOI (P<0.001) (Figure 2).

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FIGURE 1
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FIGURE 2

Conclusion: The values and the %changes of TOI and rSO2 were significantly different during DHCA. Both devices reflected the change in cerebral oxygen saturation in DHCA.

[SNACC-4] A Feasibility Study on Caffeine Citrate to Facilitate Intraoperative Brain Mapping and Cognitive Testing during Awake Craniotomies

Yang, J, Guo S. University of Washington, Bellevue, Washington, United States

Backgrounds: Awake craniotomy is usually performed when eloquent cortical tissue is located in close proximity to the resected area. The success of an awake craniotomy relies on a valid intraoperative brain mapping and cognitive test. In recent studies, intravenous caffeine was shown to be safe and accelerated emergence from isoflurane anesthesia. There are interests whether caffeine could facilitate intraoperative testing by accelerating emergence and preventing post-emergence drowsiness. To our best knowledge, the safety of intravenous caffeine administration during awake craniotomies was not examined.

Methods: We conducted a retrospective chart review on awake craniotomy patients receiving intravenous caffeine citrate during emergence before intraoperative brain mapping and cognitive testing during August 2021 and Feb 2022 in a tertiary care university hospital. Patients’ characteristics, baseline symptoms and neurological deficits, tumor characteristics, caffeine citrate dosage, pre- and post-mapping anesthetic formulation, infusion rates, airway management, duration of emergence (defined as from the end of surgical exploration to patient meaningfully following commands), intraoperative awake time (between following commands to resuming sedative infusion after testing), intra-testing sustained hemodynamic or behavioral perturbations (e.g., hypertension (systolic blood pressure >140 mmHg), tachycardia (heart rate >100 beats per minute), arrhythmia, anxiety, and agitation), brain mapping and cognitive testing issues (e.g., abnormal electrocorticography signals, prolonged drowsiness that prevented testing) were recorded.

Results: Five patients receiving awake craniotomy by 2 surgeons were included. They aged from 53 to 72 years old, were 80% female, and had BMI between 27.3 and 36.2. Before the brain mapping and cognitive testing, laryngeal mask airway was placed in 3 patients and 2 patients did not have any airway instrumentation except for nasal trumpets. Four patients received 15 mg/kg of caffeine citrate and one received 4 mg/kg. Dexmedetomidine (ranging from 0.2-0.7 mcg/kg/hr, following loading dose 1 mg/kg in 10 min), propofol (ranging from 15-125 mcg/kg/min, with intermittent bolus), remifentanil (0.02-0.15 mcg/kg/min), fentanyl were given pre-testing in 4, 5, 3, and 1 patient, respectively. Emergence time ranged from 4 to 8.5 minutes and intraoperative awake time ranged from 40 to 74 minutes. One patient reported subjective performance anxiety and presented with mild hypertension and tachycardia that required pharmacologic interventions. No arrhythmia, agitation, and brain mapping and cognitive testing issues were recorded.

Discussion: In our case series, intravenous caffeine citrate administration was safe and feasible during awake craniotomies. Its utility to accelerate emergence or facilitate intraoperative brain mapping and cognitive testing warrants further investigation.

[SNACC-5] A mannequin-based non-randomized cross over simulation study for emergency airway rescue during inadvertent accidental extubation in prone position

Rajaleelan W, Tuyishieme E, Dinsmore M, Unger Z, Venkataraghavan L. University of Toronto, Ottawa, Ontario, Canada

Introduction: Accidental extubation during prone position can be a life-threatening emergency requiring rapid establishment of airway. However there is limited evidence of the best airway rescue method for this potentially catastrophic emergency. Aim of the study was to determine the most effective method for airway rescue in case of an inadvertent extubation during prone positioning by comparing two techniques using three devices namely the supraglottic airway, video laryngoscope, and fiber optic bronchoscope.

Methods: This is a non-randomized cross-over mannequin quality study comparing the airway rescue performances of three techniques using two devices namely the supraglottic airway (IGEL), video laryngoscope (CMAC), and fiber optic bronchoscope(FOB). A Mayfield pin was placed on a mannequin in the OR, which was fixed to the OR table and the mannequin was fixed in the prone position. Anesthesia participants (fellows and staff) were instructed to insert a standard #4 LMA igel ,a ET with a CMAC and an ET with a fiberoptic bronchoscope in an order of their preference, into the mannequin in the standard surgical prone position. The participants were given the option of adjusting the height of the table prior to the airway intervention, however no other modifications to the mannequin position were permitted. Successful airway was confirmed by observation of bilateral inflation of mannequin lungs using an AMBU bag. Time (seconds) to successful airway was recorded.

Results: Twenty-three participants 11 (47.8%) Staff anesthesiologists and 12(52.1%) anesthesia fellows) were recruited for this study. Five (23.8%) participants (2 staff and 3 fellows) had a prior experience of handling an inadvertent prone extubation in their career. The mean experience of the participants in anesthesiology as a specialty was 11.939(5.76) years. All the participants were successful in establishing a supraglottic device as a temporary salvaging device.5 fellows (21.1%) and 2(8.6%) staff failed to establish a definitive ET tube using the CMAC and 1 (4.3%) fellow and 1 4.3%) staff failed to establish a definitive ET using the FOB before the allotted time of 180 secs therefore concluding it as a failed attempt.

The mean (SD) time taken to secure the airway using the LMA was 18.65(5.01) seconds amongst the fellows and 17.61 (4.67) sec amongst the staff. The mean time taken to secure the airway using the CMAC was 80.96(42.56) sec amongst the fellows and 95.19(28.45) sec amongst the staff. The mean time taken to secure the airway using the FOB was 67.55(29.06) sec amongst the fellows and 51.60(27.03) sec amongst the staff. There were significant differences in the time required for definitive airway management between the supraglottic airway and video laryngoscope [Mean (SD)=69.64 (36.32) 95% CI=53.94-85.35 t(22)=9.19, P<0.001] ,the video laryngoscope and fiber optic [Mean(SD)=27.84(44.12)95% CI=CI=8.76-46.93,t(22)=3.02,P=0.006)],the fiber optic and supraglottic airway[ (Mean(SD)=41.80sec (27.30),95%CI=29.99-53.60t(22)=7.43, P<0.001)].

Number of years of prior experience as a staff did not make a significant difference in time take to establish a definitive airway. Fellows, compared to staff were faster in establishing a definitive airway using a CMAC and slower using a FOB, but they failed more times than the staff anesthesiologists.

Conclusion: Accidental prone extubation can be an acute emergency. A LMA can be used as a temporary airway and the CMAC and FOB can be used to establish a definitive airway with an ET.Adequate training in prone intubation techniques should be part of the curriculum for training residents, fellows and staff during airway simulation education. In the case of accidental inadvertent extubation during prone position, the results of this simulation study suggest that the supraglottic airway is faster and has higher success rate in comparison to the FOB and the CMAC as a rescue airway device (Fig. 1).

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FIGURE 1:
Participant attempting to secure the airway using CMAC.

[SNACC-6] Airway bleeding in the PACU: A cautionary tail involving Neuro-IR

Krause M, Filipovic M, Steinberg A, Newhouse B, LaBuzetta J, Srejic U, Fejleh A, Tran M, Pearn M, Lemkuil B. UCSD Medical Center, San Diego, California, United States

A 65-year-old female with asthma and COPD, who underwent workup for syncopal episodes and headaches, was diagnosed with a left para-ophthalmic aneurysm. Aspirin 325 mg and clopidogrel 75 mg were initiated five days prior to elective treatment by neuro-interventional radiology. During the procedure, the patient received 4000 units of heparin, and flow diversion was achieved with Pipeline stent (Medtronic, Dublin, Ireland) deployment. Emergence from anesthesia was notable for coughing secondary to reactive airway disease and transient hypertension with a systolic blood pressure of 200 mmHg. The patient was suctioned and extubated awake. Post-extubation, she was neurologically intact but complained of throat soreness during transport to the postoperative acute care unit. Thirty minutes after extubation, her nurse noted that the patient was coughing up small amounts of blood. Five minutes later, the airway pager was called for copious blood emanating from the patient’s mouth. An attempt to rapidly secure the airway occurred after preoxygenation with RSI and direct laryngoscopy. The glottic opening was not visualized due to profound hemorrhage despite continuous suctioning. The endotracheal tube was passed into an area where bubbles had been seen, followed by end-tidal CO2 confirmation. The oropharynx was packed, fluids and blood were administered, and heparin was reversed with protamine. A spot sign on CTA suggesting hemorrhage from a branch of the left ascending pharyngeal artery was confirmed in the neuro-interventional suite and embolized. Following embolization, the patient was taken to the operating room for incision and drainage of neck hematoma and oropharyngeal examination. The left tonsil, left pharyngeal wall, posterior pharyngeal wall, and soft palate were distorted and difficult to differentiate by an experienced ENT surgeon. However, bleeding had markedly improved, and the area was re-packed using hemostatic agents. A left soft palate laceration was noted, and diffuse swelling precluded visualization of the glottic opening. The anatomic swelling and distortion persisted, resulting in an elective tracheostomy four days later. The patient was decannulated and tolerated oral intake one week later.

The precise hemorrhagic etiology remains uncertain. Mechanical soft tissue injury may have occurred due to intubation or suctioning, although immediate oropharyngeal bleeding would have been expected. Based on conversations with the ENT surgeon, profound swelling and intramuscular hemorrhage would not be consistent with primary oral tissue injury. Alternately, the sore throat may point towards a spontaneous retropharyngeal hemorrhage due to coagulopathy, coughing, or hypertension. Subsequent oropharyngeal communication may have occurred during recovery due to coughing or suctioning. Previous case reports and timing of bleeding onset support this theory.

Regardless of etiology, this case highlights a rare, life-threatening perioperative complication of a neuro-interventional procedure. Flow diverting stents commonly used to secure intracranial aneurysms carry significant thrombotic risk. As such, dual antiplatelet therapy is required for at least three months. In addition to profound platelet inhibition, intraoperative heparinization is often needed. The combination of medications impairing coagulation may have contributed to the reported complication and severity. Although the role of mechanical soft tissue injury in our case is uncertain, caution to avoid soft tissue injury should be employed. Abnormal postoperative oropharyngeal pain, difficulty swallowing, or voice changes should raise one’s index of suspicion for retropharyngeal hemorrhage. Like other causes of acute neck hemorrhage, rapid airway management may be required, and extreme difficulty should be anticipated due to impaired visibility and rapid anatomic distortion.

[SNACC-7] Alternative Electrode Placement to Facilitate Abbreviated Frontal EEG Monitoring in Surgeries Involving the Head and Face

Chauhan V*, Chang B*, Cassim T*, Rajan S, Graves M*, Garcia P*. Columba University Medical Center, New York, New York, United States*. UT Health Houston, McGovern Medical School, Houston, Texas, United States

Introduction: Abbreviated frontal EEG monitoring using monitors approved for titration of anesthetic medications (e.g., BiS® and Sedline™) are often abandoned in neurosurgical cases because the surgical approach might involve scalp near the recommended locations for electrode placement. This can be a problem as perioperative EEG monitoring can be particularly useful in these surgeries in optimizing the anesthesia delivery and enhancing the recovery profile. Here we investigate both bilateral and unilateral alternative electrode positions of the Sedline™ (Masimo, Inc. Irvine, California) sensor that might be used for continuous perioperative EEG monitoring, during surgeries that involve the head and face.

Methods: Data for this sub-analysis were collected from participants enrolled in an IRB approved study (IRB: AAAT9632). Data were collected in participants receiving general anesthesia, pharmacologic sedation, and in the absence of analgosedative agents. In most cases, we were able to compare 5 alternate electrode positions in each patient. Spectral edge frequency (95%-ile, SEF95) and patient state index (PSI) were measured in 20 second epochs for approximately 5 minutes in each configuration (15 measurements per electrode configuration). The recommended electrode placement was used as the standard comparator except where otherwise notes. Statistics performed (t-test) with GraphPad™ Prism).

Results: Data collection remains ongoing, and here we present our preliminary analysis of pilot data. Both intra-subject and inter-subject analyses are planned. Figure 1 summarizes the data for one subject not receiving sedation. Only one alternate electrode configuration (malar electrodes) failed to demonstrate a significant change in average PSI as compared to the standard bifrontal upright configuration (P=0.397). The bifrontal inverse, semi-lateral, and lateral upright configuration resulted in significantly different average PSI (P<0.0001). The lateral inverse configuration also demonstrated a difference in PSI (P=0.0036). Unilateral lead placement did not result in a statistically significant difference in asymmetry (absolute value of SEF95L- SEF95R, P=0.7916, unilateral vs bilateral). The semi-lateral position was excluded from the asymmetry analysis as it is not symmetric bilaterally. We also observed that inferior placement of frontal electrodes results in a decrease of SEF95).

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FIGURE 1:
Sedline Placements Showing Different Spectograms and Abbreviated EEG Variables’ Values.

Conclusion: Our preliminary results suggest that alternate electrode configurations are achievable and may help guide the delivery of anesthetic agents, especially for providers comfortable with interpretation of quantitative EEG and analysis of the raw time-series EEG waveform. Although most alternate configurations resulted in a change of PSI, in general the magnitude of this change might be considered clinically insignificant. Caution should be exhibited with interpretation of EEG when the leads are placed inferiorly as attenuation of higher frequency activity may result in impairments in recognizing the “beta buzz” typically indicative of cortical activation.

[SNACC-8] An audit on Post Craniotomy Pain Management in a Tertiary University Hospital: A Quality Improvement Initiative

Wan Zakaria W, Tan W. University Malaya, Wilayah Persekutuan, Kuala Lumpur, Malaysia

Management of post craniotomy pain is challenging, especially to find the balance between providing adequate but also to avoid excessive analgesia that could mask new onset neurological deficits. Poorly managed post-operative pain will lead to many complications which result in overall delayed recovery, prolonging hospital stay and ultimately, an increase in healthcare costs.

Aim: To evaluate the management of post craniotomy pain management at a single tertiary university hospital in Kuala Lumpur, Malaysia.

Methods: A retrospective analysis on all patients above 18 years old who underwent elective craniotomy between June 2021 to December 2021. Patient demographics, site of craniotomy, pre and post-operative pain scores and analgesics, number of ICU days, and any post-operative cardiovascular, renal, respiratory or gastrointestinal complications in the first 72 hours following craniotomy, were collected from patients electronic medical records.

Results: A total of 36 patients were recruited with 28 patients who had supratentorial versus 8 patients who had infratentorial craniotomy. More female patients were in the supratentorial group however, other patient demographics such as age, weight, height and BMI were comparable. Most of the patients recruited were ASA-PS Class II.

Most of the patients received general anaesthesia (GA) with Sevoflurane while only one patient in the supratentorial group received total intravenous anaesthesia (TIVA). Intraoperatively, all patients received intravenous Remifentanil and paracetamol. Skin infiltration at surgical site was performed in all but one patient who received regional scalp block. The most striking differences were patients in the infratentorial group received a higher Remifentanil target effect site (more than 4 ng/mL) and also higher doses of intravenous Morphine within 72 hours perioperatively (mean 5.5 mg vs 3 mg).

Post-operative pain scores were higher in the infratentorial group in post-operative Day 1, and most of the supratentorial group of patients reported mild pain and remained pain free in the subsequent days (P value 0.003). All patients continued to receive intravenous paracetamol and intravenous parecoxib was added after 24 hours. Higher percentage of patients in the infratentorial group (50% vs 28.5%) requires intravenous morphine during the post-operative period.

As expected, a higher percentage of patients who had infratentorial craniotomy required longer ICU stay (50% vs 10%). Transient neurological deficits were seen in 2 out of 8 patients (25%) in the infratentorial group compared to 3 patients (10%) in the supratentorial group. A total of 2 patients from the supratentorial group developed ECG changes, and 1 was unable to tolerate orally. However all complications were resolved by Day 3 post-operatively. There were no mortalities recorded.

Conclusion: Based on this audit, majority of the elective post-craniotomy patients experienced manageable pain with very few complications, however a larger sample size is desirable to represent the target population. From this small study we can conclude that although we are practising a multi-modal analgesia approach, a standardised pain management protocol will be beneficial. This will be a part of the unit’s Quality Improvement initiative towards implementing an Enhanced Recovery In Neurosurgery protocol, locally.

[SNACC-9] Anaesthetic management and outcomes of patients undergoing embolization of brain Arterio venous malformations by “Pressure cooker technique”: Retrospective case series study

Srinivasaiah R, Kumar V, Chandran A, Puthuran M. The Walton Centre, Liverpool, United Kingdom

Introduction: The treatment of brain arteriovenous malformations (AVM) represents a therapeutic challenge, regardless of chosen modality of treatment. Traditionally endovascular embolization of Intracranial AVM’s has been used as preparation of patients for surgical resection or radio-surgery. However, the new technique employed in the Trans-venous embolization of brain AVMs also known as “Pressure cooker technique” (1) can be used as sole treatment method to cure the AVM’s. This new technique often necessitates some means of arterial inflow control to prevent reflux of embolic agent and to aid retrograde penetration of the liquid embolic agent from venous to the arterial side(nidus). Anaesthesiologists play an important role in reducing the blood flow through AVM to cause flow arrest during embolization by various techniques. We share our experience of managing Embolization of Intracranial AVM’s under hypotensive anaesthesia.

Methods: All AVM patients treated via trans-venous embolization over 2 years period between December 2017 to November 2019 were included in this study. We collected the data on patient demographics, grade & location of AVM’s, ASA grade, anaesthetic technique, hypotensive agents used, duration of hypotension, peri procedure complications, post procedure angiogram at 3 months to look at AVM occlusion and outcome at 1 year measured by modified Rankin score (MRS).

Results: We treated 10 patients during this period with trans-venous embolization of Intracranial AVM’s of which 7 patients were Male and 3 were females. The mean age of these patients was 38 years (range 20-61 y), 7 of these patients had higher Spetzler-Martin AVM grade of 3 or more and AVM was in deep location like quadrigeminal plate, basal ganglia, cerebellum. All the patients received General anaesthesia with inhalation technique, Labetalol was the most commonly used drug for maintenance of hypotensive anaesthesia. Duration of hypotension ranged between 26 minutes to 180 minutes depending on the complexity of AVM’s. Degree of hypotension depended on patient comorbidities and varied between MAP of 50-70 mm hg. One patient had Intracranial haemorrhage requiring craniotomy and evacuation of clot. The angiograms performed at 3 months showed complete occlusion of AVM’s in 9 patients and one patient had 90% occlusion. All the 10 patients were alive at 1 year and 9 patients had a favourable outcome of MRS 0-2 and 1 patient had outcome of MRS 3.

Discussion: Various techniques have been employed to achieve reduced blood flow through AVMs. Intravenous Adenosine has been used to cause transient asystole and flow arrest, however it cannot be used in all patients and is associated with haemodynamic complications. Rapid ventricular pacing (2) has also been used to achieve the flow arrest however the evidence of this in interventional neuroradiology is limited. Selective temporary flow arrest during embolization can also be achieved by placement of intraarterial balloons to reduce intra-nidal pressure and flow (3). In our centre we performed arterial embolization of AVM’s and insertion of flow coils to reduce the blood flow through AVM nidus followed by venous embolization with Onyx/Squid under hypotensive anaesthesia with a MAP of 50-70 mmhg. We also employed cessation of ventilation for up to a minute at the time of trans venous injection of Onyx. Both these simple measures prevented the movement of Onyx and helped in obliterating the AVM without resorting to complex techniques which has an effect on haemodynamics.

To conclude Trans-venous embolization can be safely used as curative technique in the treatment of intracranial AVM’s as it has shown to be safe, effective and curative in 90% of the patients. Hypotensive technique can be successfully used in the management of curative trans-venous embolization of AVM’s to hold the glue at the venous end of AVM (Fig. 1 and 2).

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FIGURE 1:
AVM before embolization.
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FIGURE 2:
After trans-venous embolization.

[SNACC-10] Anesthetic Considerations for Chiari I Malformation in a BMI 62 Patient

Patel D*, Palmeri N*, Yeh C*, Hussain H. University of Illinois College of Medicine, Chicago, Illinois, United States*. Rosalind Franklin University, Chicago, Illinois, United States

Patients with Chiari I malformations present with tonsillar herniation below the foramen magnum causing abnormal spinal anatomy. Anesthesia challenges in this population include difficult airway management, monitoring intraoperative autonomic dysfunction, avoiding increased intracranial pressure, and accommodating sensitivity to neuromuscular blockade. We present a case with an additional airway management challenge due to morbid obesity with a BMI of 62. A 23 year old female with a history of Covid pneumonia and morbid obesity who presented with syringomyelia and Chiari I malformation. She initially presented with bilateral numbness, tingling, weakness, and pain in her hands. Imaging with MRI at the time showed downward displacement of the cerebellar tonsils with the tips reaching the lower portion of C1 and overall 10-12 mm displacement below the level of the foramen magnum. Syrinx was also visualized from the level of C1-C2 extending down to the level of T5-T6. Repeat MRI a year later showed no significant changes. However, she has worsening symptoms of pain in her right arm preventing her from working. She is agreeable to surgical decompression of the posterior fossa through a suboccipital craniotomy with resection of the posterior arch of C1 with duraplasty. Significant findings on the physical exam include Mallampati III, shorter thyromental distance, and limited range of motion of her cervical spine due to pain in her arms. We chose awake fiberoptic intubation due to difficult airway from morbid obesity and limited cervical spine range of motion and the consideration of hypercapnia induced from brief apnea the patient may not tolerate. She was premedicated with versed, glycopyrrolate, and dexmedetomidine, and given a 5% lidocaine paste “lollipop” to topicalize oropharynx. She was also started on a low dose remifentanil infusion for sedation during the awake fiberoptic approach. Blood pressure, heart rate, respiratory rate with continuous end-tidal capnography, and pulse oximetry were monitored during the awake fiberoptic intubation. A 7.0 endotracheal tube was lubricated with viscous lidocaine and placed over a fiberoptic scope. Once there was visualization of the vocal cords, additional 2% lidocaine was administered directly at the vocal cords. She was intubated smoothly on the first attempt. She was then immediately induced to general anesthesia with propofol and non-depolarizing muscle relaxant to avoid using succinylcholine due to the possible hypersensitivity caused by denervation. Intraoperatively, a conventional air warmer was used to prevent hypothermia. Invasive arterial blood pressure monitoring was applied. Normotensive blood pressure and normocapnia were maintained throughout the surgery. Muscular blockade was reversed with sugammadex at the end of surgery to ensure adequate ventilation especially with the patient’s body habitus. Upon extubation, the patient had acute hypertension which was managed by nicardipine infusion and hydralazine boluses. Patient was taken to a neurosurgical intensive unit and monitored for two days. She was discharged home without any complication.

In conclusion, anesthetic considerations for patients with Chiari I malformation include airway management, monitoring for autonomic dysfunction, avoiding increase in ICP, and optimizing postoperative neurological status with balanced anesthetic management.

[SNACC-11] Anesthetic management for intradural clip ligation and reconstruction of recurrent previously coil - embolized complex anterior communicating artery aneurysm: A Case Report

Elser A, Chakraborty I, Day J, Gupta P. University of Arkansas for Medical Sciences College of Medicine, Little Rock, Arkansas, United States

We present a 33-year-old male patient with a history of ruptured anterior communicating artery cerebral aneurysm, which was then coil embolized in 2016. In March 2022 he was found to have a large recurrence of this aneurysm at the coiling site from a dominant left anterior cerebral artery with a new superiorly projected aneurysm measuring 4.7×3.6 millimeters and an inferior portion measuring 5.9×4.8 millimeters. This time, a left orbitocranial skull base approach was performed for intradural clip ligation and reconstruction of the recurrent aneurysm.

A combined inhalational and intravenous general anesthetic was administered. Neuro-monitoring was performed with somatosensory evoked potentials, motor evoked potentials, and electroencephalogram for the entirety of the case. After the dura was exposed and burst suppression was achieved, the area was dissected to reveal the previously coiled aneurysm and corresponding vessels required for clipping. Temporary clips were placed, and the previously embolized portion of the aneurysm was excised. However, there was initial difficulty optimizing vessel flow while also obtaining optimal clip placement. This process of optimization was complicated by intraoperative aneurysm rupture, which was efficiently controlled. Temporary hypotension was achieved with small boluses of intravenous nitroglycerine which created a bloodless field for the surgeon to clip the aneurysm rupture. During clip manipulation, decreased amplitude of motor evoked potentials in the right lower extremity were noted without any change in the somatosensory evoked potentials. After the clips had been repositioned in their final location, motor evoked potentials slowly recovered to their pre-clipping baseline. The remainder of surgery and emergence from general anesthesia were uneventful. Postoperatively, the patient exhibited right-sided hemiparesis and mild dysarthria, both of which improved within 48 hours and prior to patient’s discharge from the hospital (Fig. 1).

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FIGURE 1:
Excision of previously embolized cerebral aneurysm in progress.

[SNACC-12] Anesthetic Management of Patients with Hypothalamic Hamartoma-A Retrospective Study

Seshan J, Rath G, Bindra A, Chandra P, Doddamani R. Department of Neuroanaesthesiology & Critical care, AIIMS, New Delhi, Delhi, India

Introduction: Hypothalamic hamartoma (HH), with an incidence of 1:200,000 children, is a recognized cause of drug refractory epilepsy (DRE) and endocrine abnormalities. Surgery for DRE has become increasingly popular with the advent of modern minimally invasive techniques aimed at reducing the morbidity. Possible anesthetic concerns in HH includes that of pediatric age group, interaction with anti-epileptic drugs (AED), and endocrinopathies.

Materials: After institute ethics committee approval, a review of perioperative medical records and anesthetic charts of patients who underwent surgery for HH over a period of 5 years (2016-2020) was done. Preoperative data including demographics, neurological status, AED therapy, and endocrine status was collected. Surgical method, anesthetic technique, blood loss, fluid administered and details of any intraoperative adverse event were sought. Details of postoperative ventilation, if any, duration of ICU and hospital stay, and postoperative complications were also recorded.

Results: Eighteen patients diagnosed with HH (15 children and 3 adults) underwent 24 procedures [Stereotactic radiofrequency ablation in 21 (87%) and craniotomy for excision/disconnection in 3 (13%)]. Median age was 6 years (IQR 3,8). All patients were treated for DRE with atleast 3 AEDs, Levetiracetam 11 (61%) and Clobazam 9 (50%) being the most common. Precocious puberty was the major endocrinological manifestation in 7 (39%) patients. Airway abnormalities included obstructive sleep apnea and bifid epiglottis in 1 patient each. Balanced anesthesia with Fentanyl, Sevoflurane and Rocuronium was used in all patients. Intraoperative events noted were tense brain and suspected venous air embolism in 1 patient each. Seven (29%) patients were ventilated postoperatively due to inadequate awakening or surgical handling. Postoperative complications included dyselectrolytemia [3 (12%)], respiratory events [2 (8%)], hypothyroidism in 5 (27%) and hypocortisolism 2 (11%). Duration of ICU stay was 2 days (IQR 1,5).

Conclusions: Anesthesia for minimally invasive approach to DRE is safe. Possibility of AED interaction and surgical site edema should be considered in delayed awakening from anesthesia. Endocrinopathy causing dyselectrolytemia should be promptly managed.

[SNACC-13] Anisocoria After Craniotomy

Churchill T, Knutson A, Hemmer L. Northwestern, Chicago, Illinois, United States

Introduction: Many complications of craniotomies can be identified by physical examination soon upon emergence from anesthesia. A neurologic exam is often performed to identify new onset weakness or cranial nerve abnormalities. In the case of a dilated pupil (anisocoria) after craniotomy there are several possible explanations, but the immediate concern is for increased intracranial pressure (ICP) and brain herniation. Dilation of the pupils is governed by the balance of sympathetic stimulation versus parasympathetic inhibition, so effects on either of these pathways must be considered1. Given the external position of the parasympathetic fibers in the third cranial nerve, they are especially susceptible to external compression in the cranial vault in the case of increased ICP2. As a result, most reasons for post-surgical unilateral pupil dilation are ominous and require prompt evaluation. However, when imaging is negative for etiologies of an acute increase in ICP (e.g. hemorrhage), other etiologies of perioperative anisocoria must be considered. Case: A 33 yo male with a history of refractory bilateral temporal lobe epilepsy, bipolar disorder, and iron deficiency anemia presented for bilateral stereotactic electroencephalogram (EEG) explantation. He underwent a routine standard general anesthetic with endotracheal intubation and muscle relaxation in supine position. Sevofluorane was used for anesthesia maintenance and a remifentanil infusion was used at the end of the procedure to facilitate a smooth emergence. For additional post-op pain control 20 milliliters of lidocaine 1% with epinephrine 1:100,00 was injected by the surgical team via a non-targeted scalp block above the eyebrows bilaterally. The scalp block occurred approximately ten minutes prior to emergence from anesthesia. The case lasted approximately one hour with no significant blood loss noted. Routine pupillary inspection by the anesthesiology team during anesthesia emergence identified right-sided unilateral pupil dilation. The neurosurgical team was immediately notified, and an emergency head CT was completed. The CT was unremarkable without hemorrhage or intracranial herniation.

Discussion: The cause of this patient’s anisocoria is still unknown, but the differential of unilateral pupil dilation after craniotomy is important to delineate. A review of the anatomy and physiology of the pupillary reflex can yield possible explanations. The physical dilation of the pupil occurs from the iris sphincter and dilator muscles which are governed by autonomic innervation through the ciliary nerves which pass through the retrobulbar space on their way to the eye from the cervical ganglion and back through Cranial Nerve III to the brainstem. Pharmacologic interference in the autonomic pathway (e.g. local anesthetic, epinephrine, scopolamine patch), physical interruption of the nerve signaling of Cranial Nerve III (hemorrhage, edema/inflammation, herniation), and pathologic central neurologic function (seizure activity) should all be considered when assessing a patient’s anisocoria in the perioperative period.

[SNACC-14] Assessment of impaired cerebral autoregulation by THRR using TCD and its correlation with neurologic outcome in patients with aSAH: A Prospective Observational Study

Panda N*, Katariya K, Luthra A*, Mahajan S*. PGIMER Chandigarh, Chandigarh, India*. Tata Memorial Hospital, Mumbai, India

Background: Cerebral Autoregulation (CA) is crucial in cases of neurological insult to the brain. It can be assessed by measuring Transient Hyperemic Response Ratio (THRR) using Transcranial Doppler (TCD). We aimed at assessing the incidence of impaired CA and its correlation with the neurological outcome in patients with aSAH

Methods: A prospective, observational study was conducted in 100 consecutive patients with aSAH who were planned for surgical clipping of aneurysm. THRR measurement using TCD was done for assessment of CA in preoperative and for 5 consecutive postoperative days. Neurological outcome was assessed using Glasgow Outcome Scale Extended score at discharge and 3, 6 & 12 months after discharge and its association with impaired CA was analysed.

Results: Impaired CA (THRR <1.09) was observed in 69 patients pre-operatively, 74 patients on the 1st and 2nd post-operative day, 76 patients on 3rd post-operative day and 78 patients on 4th and 5th postoperative day. Out of 78 patients who had impaired CA, 53.8% at discharge, 76.9% at 1 month, 69.2% at 3 month and 70.5% at 12 months had unfavourable neurological outcome significantly more than those with preserved CA.

Conclusion: Incidence of impaired autoregulation with ruptured cerebral aneurysm varies from 69-78% in the perioperative period as assessed by THRR. The deranged autoregulation is associated with significantly poor neurological outcome. Therefore, assessment of cerebral autoregulation using TCD-based THRR provides a simple, non-invasive bedside approach for predicting neurological outcome in aSAH.

[SNACC-15] Audit of Anaesthetic management and perioperative outcomes of children undergoing brain tumour resection surgeries in a tertiary cancer centre

Desai M. Tata Memorial Hospital, Mumbai, India

Background: Brain neoplasms in children represent 15% to 20% of all tumours in paediatric oncology. children undergoing neurosurgery present unique challenges for the anaesthesiologist. The aim of our study was to audit anaesthetic management and perioperative outcomes in children between the ages between 0-15 years, undergoing tumour resection surgeries procedures in our tertiary cancer institute over 5 years.

Aims and Objective: To audit: Intraoperative anaesthesia management :Adverse events during anaesthesia induction,Intraoperative neuromonitoring practices,Hypothermia/ Hyperthermia,A dverse events related to positions To study intraoperative complications:Hemodynamic instability - hypotension, hypertension, desaturation, tachycardia, bradycardia, arrhythmias, air embolism Blood loss, Intravenous fluid administration, Need of blood and blood products transfusion To study postoperative complications and outcomes: Post-operative elective ventilation, ,Reintubation within 24 hours after extubation, Duration of ICU (Intensive Care Unit) stay Readmission to ICU within 48 hours of discharge from ICU, Re-explorations, Electrolyte disturbances.

Method: After approval from Institutional ethical committee, retrospective analysis of prospectively collected Data was performed. Data was collected from Electronic Medical records, patient files, intraoperative anaesthesia and postoperative ICU charts.

Results: Out of 171 tumour resection surgeries, 79(46%) were supratentorial tumours, and 92( 54% ) infratentorial tumours. 43.8% children had Glial, 38% Embryonal 8% sellar ,10.2% other tumour histopathology.

  • Median age was 6 years and the median duration of surgery was 300 minutes. 21.63% tumour excisions were performed under Intraoperative neuromonitoring using TIVA.
  • 26/171 (15.2%) children had massive blood loss. Mean blood loss for embryonal tumours (25.14±22.02 mL/kg), sellar and pineal tumours (14.02±13.78 mL/kg), neural cell and mixed neural glial tumours(11.28±6.53 mL/kg).
  • Perioperative respiratory adverse events (PRAE) and intraoperative critical events were reported none. Only one child in our study needed vasoactive drug infusion intraoperatively and postoperatively. There was no event of air embolism. Median postoperative ICU stay (including for those with the massive blood loss) was 2 days. Postoperative 48 hours Mortality was1%, and 28 days mortality was 4%.
  • On univariate analysis, new found no correlation of any one of the parameters (emergeny or elective, duration of surgery and anaesthesia, WHO histopathologic grade of tumour, blood loss, and preoperative GCS) with postoperative complications.

Conclusion: Anaesthesia practices and management for paediatric neurosurgical procedures are safe in our institute as the intraoperative complications are minimal and less than what is documented in literature. (28 days mortality for tumour resection surgeries is comparable with other small studies in literature but higher from studies reported from high volume speciality centres) (Table 1).

T1
TABLE 1

[SNACC-16] Automated case-based directed reading program improves resident reading and teaching evaluations for CA-1 neurosurgical rotation: A prospective randomized crossover study

Gopwani S, Dobish M. MedStar Georgetown University Hospital, Washington, DC, United States

Introduction: Anesthesiology training programs have classically implemented lecture series’ uniformly for all trainees. Adult learners are not oriented towards postponed knowledge application but to immediate application, requiring asynchronous, personalized and just-in-time approaches. Decision support systems (DSS) provide real-time feedback, but have not been implemented to support education.

Residents read 4 hours/week but feel they should read more. Faculty also report inadequate support for intra-operative teaching. Directed reading (DR) programs are effective, but none have been real-time or case-based, which was our aim. The goal of this intervention was to build a clinical decision support system implemented to reach learners and educators in a more personalized way, based on the neurosurgical cases and anesthetics they are doing that day in the operating room, to increase PGY-2 anesthesiology resident reading and support faculty teaching. In phase 1 (P1), we evaluated if the DR program will increase PGY-2 reading and learning during their neurosurgical anesthesia rotation. In phase 2 (P2), if it would encourage intra-operative teaching and improve teaching evaluations.

Methods: Following IRB approval, DSS was built linking 144 articles to 12 rotations. We conducted a 2-phase prospective, randomized crossover study with a repeated measures design. Target population was U.S. PGY-2s. Accessible population was internal residents, and sample included 100% of accessible (n=10). Residents were surveyed for baseline reading and tested with ABA sample questions for upcoming rotations. In P1, residents were randomized into DR for 2/4 rotations, the other 2 serving as control. Directed reading topics included anesthetic management of craniotomy, spine surgery, intracranial aneurysm, Parkinson’s disease, trans-sphenoidal pituitary and Moya Moya surgery, and other relevant topics. Reading was surveyed weekly, and post-tests given after P1, utilizing paired T-tests to compare changes from baseline. Prior interventions utilize sample ABA questions as surrogate for knowledge.

During P2, residents were re-randomized for 2/4 weeks, with articles directed to residents and faculty. Residents reported reading and faculty article utilization to teach. Residents evaluated teaching on validated 5-point Likert scale, using Cohen’s d to quantify effect.

Results: Response rates were 100%. Baseline reading was 6.5 hours/week. Paired resident reading increased 2.5 hours/week during DR vs. control (P=0.0079). During DR, resident knowledge improvement was greater than control (∆=3/12 vs 2.2/12, P=0.32). Power analysis suggests n=50 for significance. In P2, paired reading differences were 5.68 hours/week (P-value=0.009). Faculty teaching frequency was 15%, but effect on teacher ratings was large (3.26/5 vs 4/5, Cohen’s d=0.81).

Discussion: Technological feasibility was established. Reading improved in DR and effect on evaluations was large. The study was underpowered for learning and showed inconsistent faculty utilization.

While measures were frequent and controlled, reading was self-reported. Accessible population was small, and P2 length limited by resident matriculation. The study lacked scale and design to show knowledge acquisition compared to historic controls or utilizing ITE/board scores.

Further steps include enhancing faculty experience by layering teaching preferences into DSS and expanding to additional trainees. Such interventions create value for GME and HCOs, streamlining teaching processes for educators and improving education.

[SNACC-17] Awake Craniotomy in the MRI Suite - a review of local practice

O’Dell T, Turner J, Appleby I, Luoma V, Sewell D. National Hospital for Neurology and Neurosurgery, UCLH NHS Foundation Trust, London, United Kingdom

Introduction: Modern awake craniotomy (AC) has been performed since the 1980s, initially for epilepsy surgery but expanding to surgery for intracranial tumours (1). Intra-operative magnetic resonance imaging (ioMRI) was first utilised in 1994 in Boston (2), to overcome the issue of intra-operative brain shift during craniotomy, and permit the surgical team to check the extent of resection before closing. The techniques have been more recently combined, aiming to remove as much tumour from eloquent areas as possible.

The interventional MRI (iMRI) suite at the National Hospital for Neurology and Neurosurgery (NHNN) consists of a 1.5 Tesla MRI scanner with an MR-conditional anaesthetic machine and operating table just outside the 5 Gauss line. This can be rotated to connect to the MRI table, and the patient is transferred into the bore of the scanner.

There have been very few studies looking at iMRI and awake craniotomies, however there has been a suggestion that the addition of the MRI scan to awake craniotomy may reduce the requirement for redo surgery (3), and that awake craniotomies in iMRI may reduce the incidence of neurological impairment compared to surgery under general anaesthesia in iMRI. As the number of iMRI theatre suites increases across the UK, increasingly AC is being performed in this environment. In our study, we looked at these patients and their various pathologies, undergoing awake tumour resections in our iMRI suite, and their clinical management.

Methods: The theatre log book in MRI was reviewed for all awake cases, a longer time window was selected due to the impact of covid. Records reviewed to exclude procedures other than awake tumour resections with intraoperative MRI scanning. Identified total of 43 cases, a number grossly affected by covid interruptions. Post operative notes and discharge letters were reviewed to ascertain Clavien-Dindo scoring for post-op complications.

Results: 43 cases, with an average patient age of 36 years (spanning 19 y to 72 y), gender ratio M:F=16:5. Mode ASA 2 (1-3), mean weight 78 kg (55-114 kg) and mean BMI 25.6 kg/m2 (20.2-35.6).

  • Most had a single ioMRI except three cases which had 2 scans, and 40% of cases had further resection after the ioMRI.
  • 44% noted complete resection on the post-operative MRI
  • Anaesthetic technique varied but asleep-awake-asleep/sedation comprised 88% of cases, with iGel used in 74% and classical LMA in 23%, and propofol/remifentanil used in 81%.
  • All patients had urinary catheters and arterial lines, no patients had central venous catheters.
  • Anaesthetic time (WHO sign-in to WHO time-out) ranged from 5 hours to 13 hours10 minutes with an average of 8 hours 54 minutes.
  • Postoperative destination was overnight recovery in 76%, HDU in 14%, and the remainder direct to the ward, where length of stay mean was 10.5 days (though mode was 4 d).
  • Clavien-Dindo score on discharge was 0 in 40%, 1 in 50%, 2 in 4.6% and 3b and 4 in 2.3%.
  • 44% were discharged with no new neurological deficit.

Conclusion: We interpret the outcomes here as very positive, with a high proportion of patients leaving hospital with low Clavien-Dindo scores or with no new deficits identified post-operatively. It is clear that awake craniotomy is safely performed in the iMRI suite. As is often the case in anaesthesia, whilst we saw some absolute consistencies (such as 100% rate of urinary catheters and arterial lines), we saw here that the anaesthetic approaches were as varied as the anaesthetists themselves.

Anaesthetists should be prepared for prolonged surgical time to ensure satisfactory surgical resection.

[SNACC-18] Awake fiberoptic intubation in a patient with severe Tetanus, autonomic dysfunction and oxygen desaturation: A case report

Chapman M*, Morano J, Puszynski M, Tung A. Northwestern University, Feinberg School of Medicine, Chicago, Illinois, United States*. Northwestern Memorial Hospital, Chicago, Illinois, United States. University of Chicago Medical Center, Chicago, Illinois, United States

Severe tetanus is characterized by muscle rigidity, muscle spasms, and autonomic dysfunction. These clinical features can worsen secretion management, prevent adequate ventilation, and predispose to respiratory failure. Existing case reports focus on asleep airway management with muscle relaxant use. We present a case of awake fiberoptic intubation in a patient with severe tetanus, autonomic hyperactivity, masseter spasm that prevented mouth opening, and hypoxemia requiring noninvasive respiratory support. Our report suggests that awake fiberoptic intubation may be a reasonable option in patients with severe tetanus, autonomic hyperreflexia, and limited access to the airway (Fig. 1).

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FIGURE 1:
Muscle rigidity due to tetanus.

[SNACC-19] Blood glutamate scavenging with pyruvate as a novel preventative approach for depressive-like behavior following traumatic brain injury in a rat model

Gruenbaum B*, Boyko M, Frank D, Severenovskaya E, Zlotnik A. Mayo Clinic, Jacksonville, Florida, United States*. Soroka University Medical Center, Ben-Gurion of the Negev, Beersheba, Negev, Israel. Dnepropetrovsk State University, Dnepropetrovsk, Ukraine

Introduction: Depression is a common and serious complication following traumatic brain injury (TBI). Both depression and TBI have independently been associated with pathologically elevated extracellular brain glutamate levels. These increased glutamate levels have been strongly correlated with poor outcomes. One method of eliminating excess brain glutamate is by utilizing the naturally occurring brain-to-blood glutamate efflux, known as blood glutamate scavenging. In the setting of TBI, blood glutamate scavenging with pyruvate has been widely shown as an effective method to provide neuroprotection by reducing blood glutamate and subsequent brain glutamate levels.

Methods: Here we evaluated pyruvate as a novel approach in the prevention of post-TBI depression-like behavior in a rat model. Male rats were divided into four groups: (1) sham-operated control with pyruvate, (2) sham-operated control with placebo, (3) post-TBI with placebo, and (4) post-TBI given preventative pyruvate. Rats were assessed for depressive-like behavior, neurological status, and glutamate levels in the blood and brain.

Results: Post-TBI neurological deficits with concurrent elevations in glutamate levels were demonstrated (P<0.01), with peak glutamate levels 24 hours after TBI. Following TBI, the administration of prophylactic pyruvate led to reduced glutamate levels (P<0.05), improved neurologic recovery (P<0.01), and improved depressive-like behavior (P<0.01).

Conclusions: Glutamate scavenging with pyruvate may be an effective prophylactic option for post-TBI depression by reducing associated elevations in brain glutamate levels.

[SNACC-20] Brain Relaxation Using Desflurane Anesthesia and Total Intravenous Anesthesia in Patients Undergoing Craniotomy for Supratentorial Tumors: A Randomized Controlled Study

Jiang Z, Wu Y, Han R, Jian M, Liang F, Liu H, Mei H. Beijing Tiantan Hospital, Beijing, China

Background: Satisfactory brain relaxation is essential in neurosurgery for sufficient surgical exposure and minimizing the damage to normal brain tissue. Desflurane anesthesia and total intravenous anesthesia (TIVA) have different effects on cerebral hemodynamics, which may potentially contribute to discrepant brain relaxation. The purpose of this study was to compare the effects of desflurane anesthesia and TIVA on brain relaxation in patients undergoing craniotomy for supratentorial tumors.

Methods: In this randomized, controlled study, we enrolled patients aged 18-60 years, with ASA I–III, who were scheduled to undergo elective craniotomy for supratentorial tumors. Patients were randomly assigned in a 1:1 ratio to receive desflurane anesthesia or TIVA. The primary outcome was the proportion of satisfactory brain relaxation, which was assessed by four designated neurosurgeons using a standardized 4-point scale upon dura opening. Brain relaxation was dichotomized to satisfactory (grades 1 and 2, representing perfectly and adequate relaxation) or unsatisfactory (grades 3 and 4, representing a firm and bulging brain). Secondary outcomes included emergence and extubation times, recovery of cognitive function and postoperative complications. The recovery of cognitive function was assessed with the Short Orientation Memory Concentration Test (scores ranging from 0 to 28, with higher scores indicating better cognitive function) by the attending anesthesiologists at 15 minutes and 30 minutes after extubation. Postoperative complications included hypertension, tachycardia, agitation and postoperative nausea and vomiting (PONV) during the recovery period.

Results: Of 369 patients who were assessed for eligibility, 111 were randomized and 110 were included in the modified intention-to-treat analysis (55 in the desflurane group and 55 in the TIVA group). The proportion of satisfactory brain relaxation was similar between the two groups: 69% in the desflurane group and 73% in the TIVA group (RR: 0.950, 95% CI: 0.748-1.207; P=0.675). The per-protocol analysis yielded a similar result (RR: 0.939, 95% CI: 0.733-1.204; P=0.619). Patients assigned to the desflurane group had shorter emergence (10 [8-13] min vs. 13 [10-20] min, P<0.001) and extubation times (13 [10-18] min vs. 17 [13-23] min, P<0.001), and better recovery of cognitive function at 15min after extubation (16 [0-24] vs. 0 [0-20], P=0.003), but experienced increased PONV (16 [29%] vs. 6 [11%] P=0.017) and tachycardia (22 [40%] vs. 9 [16%], P=0.006) during recovery.

Conclusions: Desflurane anesthesia and TIVA provide similar brain relaxation in patients without intracranial hypertension undergoing elective craniotomy. Desflurane accelerates the recovery from anesthesia but is associated with increased PONV and tachycardia during recovery period (Fig. 1 and Table 1).

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FIGURE 1
T2
TABLE 1

[SNACC-21] Can’t back down: spinal magnetic resonance imaging in a patient with excruciating lumbar pain and pathologic L2 fracture

Elias P, Huang J, Daxon B, Johnson D. Mayo Clinic, Rochester, Minnesota, United States

We present the case of a 78-year-old female with a four-month history of back pain who presented to the emergency department with acute encephalopathy in the setting of abdominal pain, urosepsis, new-onset atrial fibrillation, type 2 non-ST segment elevation myocardial infarction, and recently diagnosed atraumatic L2 compression fracture. Computerized tomography (CT) scan of the abdomen and pelvis obtained during her initial evaluation was unremarkable for gastrointestinal pathology but did reveal a partially imaged left perihilar mass with multiple tiny pulmonary nodules.

Despite appropriate treatment of urosepsis, the patient’s mental status continued to deteriorate with increasing agitation, and she was unable to tolerate any movement in bed secondary to worsening back pain. Due to suspicion for malignant spinal cord compression, the recommendation was made for magnetic resonance imaging (MRI) of the complete spine. However, the patient’s worsening mental status and delirium precluded imaging without an anesthetic. Furthermore, given the severity of her back pain and resultant inability to lie supine for imaging, the request for MRI with general anesthesia was denied by the anesthesia team.

The patient’s back pain continued to worsen, and her primary providers sought re-consideration of imaging under general anesthesia in order to facilitate goals of care discussions. After careful consideration, the decision was made to optimize her positioning and subsequently attempt cursory imaging under sedation with a minimal amount of dexmedetomidine. It was agreed that should the patient be unable to tolerate this, the MRI would need to be cancelled for her safety with CT myelogram performed instead. Ultimately, the patient was able to partially complete a brain and spine MRI with only two 8 mcg dexmedetomidine boluses throughout the one-hour procedure.

The patient’s imaging revealed widespread metastases throughout all parts of the visualized spine and numerous pathologic fractures. Her known L2 compression fracture was associated with severe spinal canal stenosis as well as compression of the proximal cauda equina (Fig. 1). Imaging of the brain revealed numerous supratentorial and infratentorial lesions. Given the extent of her disease, the patient’s family elected to transition to home hospice.

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FIGURE 1

Patient positioning is important to consider when performing a general anesthetic. Specifically with respect to severe back pain, one must assess the patient’s capacity to lie supine for up to one hour or more without general anesthesia. One case series has described acute onset paraplegia after the administration of an otherwise uncomplicated general anesthetic in two patients with severe back pain who were unable to lie supine. Both patients became permanently paraplegic secondary to spinal cord compression as a result of positioning that neither patient would have been able to tolerate while awake (1). This devastating potential complication should prompt the anesthesiologist and patient’s care team to consider CT myelogram as an alternative to MRI under general anesthesia, as the former can be obtained with a shorter duration of imaging and with the patient in the prone position.

T2-weighted sagittal MR image of the lumbosacral spine demonstrates a pathologic fracture of the L2 vertebral body resulting in advanced spinal stenosis, mass effect on the cauda equina, and redundancy of the cauda equina above the level of compression.

[SNACC-22] Cannabinoid type 2 receptor activation improves immune response in a novel model of experimental stroke

Bietar B, Tanner S. Dalhousie University, Halifax, Nova Scotia, Canada

Background: Stroke, traumatic brain injury, or other forms of central nervous system (CNS) injury initiate a local inflammatory response. The result of which is neuroinflammation. Compensatory anti-inflammatory pathways are activated to limit secondary damage due to inflammation. The associated release of immunosuppressing neuromodulators can result in system-wide immune dysregulation (CNS injury-induced immune-depression syndrome – CIDS). Our objective is to study CIDS using intravital microscopy (IVM) and to treat the condition using the synthetic cannabinoid type 2 receptor (CB2R) agonist, HU308.

Methods: We used the photothrombotic stroke (PTS) model in C57BL/6 mice and studied its effects on peripheral immunity following challenge with lipopolysaccharide (LPS). Leukocyte activation, as well as capillary perfusion of the intestinal microcirculation, were assessed using intravital microscopy (IVM). Brain TTC staining was used to measure stroke volume. Treatment with HU308 or vehicle was performed before PTS induction.

Results: PTS caused a significant reduction in the number of adhering leukocytes in submucosal venules of the terminal ileum of mice challenged with LPS compared to LPS-challenged animals without stroke. Leukocyte rolling was also impacted by PTS in the submucosal venules. Following stroke, we observed decreased mucosal functional capillary density (FCD). Treatment using the CB2R agonist, HU-308, reduced stroke size and normalized the immune response in response to LPS challenge.

Conclusion: Our results suggest that PTS with subsequent LPS challenge poses as a viable model to study CIDS using intravital microscopy of the intestinal microcirculation and more importantly that HU-308 is able to mitigate the condition (Fig. 1).

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FIGURE 1

[SNACC-23] Cerebral regional energy metabolism in patients with Traumatic Brain Injury

Bindra A*, Goyal K*, Khandelwal A, Mishra R. All India Institute of Medical Sciences, New Delhi, India*. Sharda University School of Medical Sciences and Research, Greater Noida, India. National Institute of mental Health and Neurosciences, Bengaluru, Karnataka, India

Background: We observed a correlation between cerebral perfusion pressure (CPP), intracranial pressure (ICP), and cerebral microdialysis variables in patients suffering from traumatic brain injury (TBI).

Methods: After the Institute Ethics Committee approvals, seven adult patients requiring decompressive craniectomy following TBI were enrolled, and CMD data was obtained prospectively for 72 hours. Correlations were done with bootstrapping (n=500) to obtain the confidence intervals (CI) due to the small sample size.

Results: One patient had cerebral ischemia (median LP Ratio of 265.5 and median pyruvate of 38 µmol/L.), while another patient had non-ischemic mitochondrial dysfunction (median LP Ratio 40.7 and median pyruvate 278.5). The coefficients of correlation between LP Ratio with CPP and ICP were, r=−0.05 (CI=−0.14-0.03) and r=0.09 (CI=−0.03-0.24) respectively. The coefficient of correlation between cerebral and blood glucose was, r=0.38, (CI −0.35-0.14).

Conclusion: CMD can identify cerebral ischemia and mitochondrial dysfunction, however, no correlations could be observed between LP Ratio and CPP or ICP. More studies are required to understand and treat cerebral metabolism in TBI.

[SNACC-24] Cervical Dystonia and Anterior Cervical Spine Surgery

Desamour H, Vincent A. George Washington University Hospital, Washington, DC, United States

Cervical dystonia is classified as a movement disorder that is characterized by involuntary movement (twisting, repetitive) or abnormal movement of the neck with regard to head tilt and rotation due to sustained intermittent muscle contractions. We present a case of a 37-year-old male with a history of wheelchair-dependence, cervical dystonia, severe autism, Tourette syndrome, impulsive personality disorder, hyperlipidemia, mitral valve prolapse, seizures, and cervical stenosis with significant right sided upper extremity weakness coming for anterior C4-6 cervical spinal fusion. The incidence of cervical dystonia is about 1 in 100,000 and of onset is usually 30-50 years. From an anesthetic standpoint, intubation of a patient with acute or chronic cervical dystonia poses many challenges especially pronounced in cervical spinal surgery. In this patient, behavioral issues precluded consideration of awake airway placement.

On exam, patient had a flat affect with his mother at the bedside, but he did follow commands. Cervical dystonia was not immediately prominent; however, patient had limited range of motion of his neck, i.e., an inability to extend neck beyond 15 degrees. As patient had a mouth opening >5 cm and Mallampati 1, we determined that the patient could safely be sedated and airway managed via video laryngoscopy. Consent was obtained via guardian, ASA monitors were placed, and IV accessed was gained with a 20 gauge IV. Pt received 2 mg of midazolam in the preoperative bay and 2 mg in the operating room prior to induction of anesthesia. He was moved onto the operating table, and cervical in line stabilization was maintained. Pt was preoxygenated for three minutes as surgical time out took place. He was induced with 100 mg of lidocaine 1%, followed by 150 mg of propofol, and 50 mg of rocuronium. Due to history of immobility, a decision was made to forgo succinylcholine even though neuromonitoring with motor and sensory evoked potentials was required for this procedure. As paralysis ensued, patient’s neck relaxed while maintaining ramp at 30 degrees. He was an easy mask ventilation and was intubated without difficulty with a video laryngoscope No. 3 blade and a 7.5 endotracheal tube. Patient remained hemodynamically stable throughout with depth of anesthesia maintained with propofol at 150 mcs/kg/min. In addition, dexmedetomidine at 0.5 mcs/kg/h was used as anesthetic and sympatholytic in the setting of patient’s known past combative behavior. As some studies in pediatric patients have shown onset of acute dystonic reactions in response to induction with sevoflurane, volatile anesthetics were completely avoided, and we were able to maintain an adequate depth of anesthesia throughout the procedure. Analgesia consisted of hydromorphone 1 mg. Neuromuscular paralysis was reversed for MEP monitoring to proceed. At the end of the procedure, patient was extubated without difficulty and was transported safely to post anesthesia care unit on 4L nasal cannula. His mother was brought to bedside quickly for safe re-orientation and behavioral redirection.

Positioning as well as airway management pose special challenges in spinal surgery. In patient populations with neuromuscular and behavioral disorders, additional preparations must be made for anesthetic choice, surgical positioning and provisions to keep patients and staff safe.

[SNACC-25] Challenges and Alternatives during Awake Craniotomy in patient with complete hearing loss-Our experience and Review of Literature

Chhabra S, Chowdhury T, Venkatraghavan L, Middleton W, Kongkham P. Toronto Western Hospital, Toronto, Ontario, Canada

Background: Awake craniotomy (AC) is the preferred technique for resection of brain tumours close to the eloquent areas of the cerebral cortex. Intraoperative functional brain mapping for sensory, motor or language areas, in a conscious patient, results in lower residual tumour with minimal or no postoperative neurological deficits.

The cornerstone for a successful AC is communication. Would this mean that AC would not be possible when deafness in a patient would lead to difficult communication? Wouldn’t this be putting the deaf patient at risk of losing his only means of communication, that is sign language? Here we discuss our maiden experience with conduct of AC in a deaf patient. We also review the existing literature and discuss insights into the management of these patients.

Case Report: A 66-year-old man with a left-sided intracranial lesion involving temporal posterior and angulate gyrus, was scheduled for AC. He had adult-onset deafness with minimal hearing function in left ear, that too with a hearing aid. He was able to read lips and communicated with American Sign Language (ASL). Preoperatively, the patient was counselled with the assistance of an ASL translator, regarding the importance of the surgical procedure to be done awake.

In the operating room, hearing aid and spectacles could not be worn by the patient due to the risk of contaminating the surgical site. With the neuropsychologist and ASL translator in the operating room to help communicate with the patient, conscious sedation with dexmedetomidine infusion was used as the anesthetic technique. Propofol boluses were administered for scalp infiltration with local anesthetic and pin insertion. At this point patient became agitated and it became difficult to communicate with ASL. Small boluses of remifentanil were given to complete the pinning and positioning. Dexmedetomidine was discontinued for the cortical mapping, and resection was done accordingly. Subcortical white matter tract mapping identified three areas at the base of resection cavity where the stimulation induced phonemic and semantic paraphrasias, hence no further resection was done. Patient was sedated with dexmedetomidine for closure.

The postoperative imaging was unremarkable, and patient was discharged on second postoperative day. On follow up at three weeks, occasional difficulty in sign language comprehension was reported and he was assured that such occurrences resolve in a couple of months.

Review of Literature and Discussion: There is scarce published literature describing the management of AC in deaf patients and a thorough literature search resulted in four published case reports (Table 1). We counselled the patient about the whole process with the help of ASL interpreter and administered conscious sedation which, except for some agitation at the time of pinning, was otherwise successful in having a safe and co-operative patient.

T3
TABLE 1

The sign language might fail as a means of communication when the patient has visual impairment and wearing of visual aids is not possible due to risk of contamination of surgical field. Also, with conscious sedation, a patient with normal hearing could respond to verbal commands with their eyes closed while this would make communication difficult in a sedated deaf patient if he does not open his eyes for ASL interpreter. These were to the two problems encountered in our patient and the first issue was managed with having strategic lighting in the OR so that he could see ASL in low ambient OR light.

To summarise, while AC in deaf patients is not contra-indicated (impossible), inter-disciplinary discussion and planning is important. Addressing issues unique to each deaf patient would make communication smooth in a seemingly difficult to interact scenario.

Literature review of the Awake craniotomy performed in patients with complete hearing loss.

[SNACC-26] Challenging Anesthetic Management: Bilateral Moyamoya Disease Revascularization

Beresian J, Mathur P, Nair H. Cleveland Clinic, Cleveland, Ohio, United States

Moyamoya disease (MMD) is a rare chronic cerebral vasculopathy characterized by progressive stenosis of the distal portions of internal carotid arteries and their major branches.(1) Classically, MMD manifests itself bilaterally therefore many patients present for bilateral procedures. Intraoperative management of these patients is challenging due to severe hemodynamic changes. Safe anesthetic management focuses on maintaining adequate cerebral blood flow, normalization of intracranial pressure, and avoidance of both cerebral vasoconstriction, vasodilation, and hyperthermia. We present a patient with a severe bilateral middle cerebral artery (MCA) stenosis successfully undergoing two bypasses 6 weeks apart.

Case Description: 41-year-old African American female with a history of bilateral cerebral MMD presented for right superficial temporal artery (STA)-MCA bypass. Her history was significant for right ischemic frontal and parietal lobe stroke two months prior to presentation associated with seizure activity. On the day of the surgery, the patient had no residual neurological deficits. Her other medical problems included obesity, hypertension, type II diabetes, and hyperlipidemia. Radiographic imaging showed bilateral MCA stenosis with the right being almost totally occluded. General anesthesia with controlled and stable hemodynamics was conducted with fentanyl, etomidate, lidocaine and rocuronium. ASA standard monitors applied and pre-induction arterial line inserted. Anesthesia was maintained on 0.5 MAC sevoflurane and remifentanil infusion. Sensory and motor tract integrity was confirmed during the procedure by somatosensory evoked potentials (SSEP) and motor evoked potentials (MEP) monitors. Mean arterial pressure (MAP) was maintained at 20% above baseline by phenylephrine infusion, albumin colloid IV infusion and during emergence by esmolol and labetalol. Urine output was 1.5 mL/kg/h and normothermia was maintained by forced warm air blanket. PaCO2 was maintained at around 38-40 mm Hg and blood glucose level less than 180 mg/dL. Oxygen saturation was kept at 99–100%. Before emergence patient had ondansetron, adequate analgesia, and adequate neuromuscular blockade reversal. After smooth tracheal extubation, her neurological examination was close to baseline. She was transferred to the neurosurgical intensive care unit. The patient was discharged home four days after the surgery in stable conditions. After six weeks, she had the left (STA)-(MCA) bypass with the same set up and sent home in four days.

Conclusion: We describe a challenging management of MMD requiring unique anesthetic approach. The principle in the anesthetic management of MMD is to maintain a balance between cerebral blood flow and oxygen consumption(2). Therefore, blood pressure goals should be clearly discussed with the surgeon prior to surgery and awake arterial line inserted for hemodynamically smooth induction. Aiming for a tight range of mean artery pressure is very demanding and numerous pharmacological agents should be utilized simultaneously. Since most patients have bilateral involvement, one sided repair does not fully reverse the pathology and these patients will need close ICU monitoring post operation.

References:

1. Berry JA, Cortez V, Toor H, Saini H, Siddiqi J. Moyamoya: An Update and Review. Cureus. 2020;12(10):e10994.

2. Parray T, Martin TW, Siddiqui S. Moyamoya disease: a review of the disease and anesthetic management. Journal of neurosurgical anesthesiology. 2011;23(2):100-9.

[SNACC-27] Chemogenetic activation of dopaminergic midbrain neurons in rats accelerates cognitive recovery following dexmedetomidine- but not ketamine-induced loss of consciousness

Vincent K*, Cho A, Solt K*. Massachusetts General Hospital, Boston, Massachusetts, United States*. Touro College of Osteopathic Medicine, New York, New York, United States

Introduction: Dopaminergic midbrain neurons, specifically those in the ventral tegmental area, are critically involved in restoring consciousness following general anesthesia. Whether these circuits contribute to cognitive recovery following emergence, however, is unknown. Recently, we established a novel and clinically relevant cognitive recovery testing paradigm for rodents using an adapted version of the 5-Choice Serial Reaction Time Task (5CSRTT). In it, higher order neurocognitive processes, such as attention and working memory, are tracked in real-time following emergence to establish neurocognitive recovery trajectories. Importantly, we found that young, healthy rats recover cognitive function rapidly following isoflurane, sevoflurane, and propofol, but have delayed cognitive recovery following dexmedetomidine- and ketamine-induced loss of consciousness (LOC). To assess whether circuits known to be involved in re-establishing consciousness can be similarly exploited to hasten cognitive recovery, we employed chemogenetic techniques to activate midbrain dopaminergic neurons in rats following dexmedetomidine and ketamine-induced LOC. As we have previously observed that pharmacologic activation of dopaminergic pathways hastens emergence from dexmedetomidine, but not ketamine-induced LOC3, we hypothesized that activating dopaminergic midbrain neurons would differentially affect cognitive recovery following dexmedetomidine and ketamine exposure.

Methods: Eight adult Sprague Dawley rats (4 male, 4 female) were trained on the 5CSRTT until they achieved high accuracy (>80%) and low omissions (<20%). Once trained, midbrain neurons were targeted using a combinatorial adeno-associated viral (AAV) strategy to drive selective Designer Receptors Exclusively Activated by Designer Drugs (DREADDs) expression in dopaminergic neurons. The dopamine targeting virus, AAV9-rTH-Cre, was co-injected with the Cre-dependent excitatory DREADD, AAV2-DIO-hM3DGq-mCherry, into the midbrain (+/−0.9ML, −4.8AP, -8.3DV). After waiting three weeks for DREADDs expression, rats were exposed to dexmedetomidine (20 μg/kg, i.v. infused over 10 min) or ketamine (50 mg/kg, i.v. infused over 10 min). Following infusion, rats were administered either clozapine-N-oxide (CNO, 3 mg/kg, i.p.), to activate DREADDs, or saline in a randomized order. Rats were placed supine in the testing chamber to recover. Following the return of the righting reflex (RORR), rats had three hours to perform the task. Recovery of working memory was measured as the time taken following RORR to achieve ≥80% accuracy in five consecutive trials. Recovery of attention was measured as the time taken following RORR to achieve ≤20% omissions in five consecutive trials. Recovery latency was compared between CNO and saline conditions by Mantel-Cox comparison. The probability of cognitively recovering was compared by Hazard Ratio (HR) using the Mantel-Haenszel method.

Results: Following RORR from dexmedetomidine, the median latency to recover high accuracy, a metric of working memory, was 114.7 minutes with saline and 49.7 minutes with CNO, but this was not significantly different (χ2=2.705, P=0.1001) (Fig. 1A). However, recovery of a low omission rate, a metric of sustained attention, following dexmedetomidine was significantly faster in the CNO condition (χ2=5.588, P=0.0104) (Fig. 1B). Rats given CNO were also significantly more likely to recover a low omission rate following dexmedetomidine than saline (HR=3.801, 95CI[1.4, 17.4]). In contrast, CNO had no impact on cognitive performance following ketamine exposure. Median recovery of high accuracy was 42.9 minutes with saline and 45.6 minutes with CNO (χ2=0.9155, P=0.3387) (Fig. 1C). Median recovery of low omissions was 70.5 minutes with saline and 68.5 minutes with CNO (χ2=0.3793, P=0.5380) (Fig. 1D).

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FIGURE 1:
Probability of cognitive recovery following dexmedetomidine (A-B) and ketamine (C-D) induced loss of consciousness.

Conclusions: Here we demonstrate that selective activation of midbrain dopaminergic neurons hastens neurocognitive recovery following dexmedetomidine-induced LOC in rats. Interestingly, these circuits have no impact on cognitive function following ketamine. These data suggest there are distinct mechanisms by which the brain restores cognitive function following anesthetic-induced breaks in consciousness. Identifying these mechanisms will be key to designing effective strategies for facilitating neurocognitive recovery.

[SNACC-28] Choice of anesthesia for endovascular treatment of acute ischemic stroke in the posterior circulation (CANVAS II): An exploratory randomized controlled trial

Wang X, Han R, Liang F, Wu Y. Capital Medical University, Beijing, China

Background: There is no definitive conclusion on the best choice of anesthesia for people with acute posterior circulation stroke during endovascular treatment (EVT).

Methods: We performed a double-center, randomized, parallel-group, exploratory trial (CANVANS II trial, NCT03317535) with blinded endpoint evaluation enrolled patients in China from March 2018 to June 2021. Ultimately, eighty-seven patients were involved in the intention-to-treat analysis, 43 with GA and 44 with CS; other patients did not meet the eligibility criteria. Six were excluded due to missing primary outcomes or stopped therapy. All analyses were unadjusted or adjusted with the per-protocol and intention-to-treat (ITT) principle. Participants were randomly divided into CS or GA (1:1 ratio) before starting treatment. The primary endpoint was neurological disability at 90 days evaluated with the modified Rankin Scale (mRS). In addition, other important clinical outcomes, such as functional independence (mRS ≤2), successful reperfusion (mTICI 2b-3), etc., were also recorded.

Results: The CS group had a higher incidence of functional independence; however, no significant difference was found between the two groups (48.8% vs. 54.5%, RR 0.89, 95% CI 0.58 to 1.38; adjusted OR 0.91, 95% CI 0.37 to 2.22). However, GA performed better in successful reperfusion (mTICI 2b-3) under ITT analysis (95.3% vs. 77.3%, adjusted OR 5.86, 95% CI 1.16 to 29.53). In the CS group, thirteen people (28.5%) were transferred to GA.

Conclusions: Compared with GA, CS did not show a marked advantage in functional outcomes at 90 days in adults with acute posterior circulation stroke treated with EVT. Keywords: ischemic stroke, general anesthesia, posterior circulation, endovascular thrombectomy (Fig. 1).

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FIGURE 1:
Modified Rankin Scale (mRS) Score Distribution of intention-to-treat analysis and per-protocol analysis.

[SNACC-29] Comparison of propofol and desflurane for postoperative neurocognitive function in patients with aneurysmal subarachnoid hemorrhage: A Prospective Randomized Control Trial

Mahajan S, Bhagat H, Mohanty M, Panda N. Postgraduate Institute of Medical Education and Research, PGIMER, Chandigarh, India

Background: Aneurysmal Sub-Arachnoid Hemorrhage (aSAH) is an acute life-threatening condition with high mortality. 40-50% of the survivors have cognitive dysfunction, affecting the quality of life. The anesthetic agents play a pivotal role during intracranial aneurysmal surgery. However, there is a lack of substantial evidence of their effect on postoperative neurocognitive function. This study evaluates the effect of propofol and desflurane as anesthetic agents on postoperative neurocognitive function in patients undergoing surgical aneurysmal clipping.

Methods: 100 patients undergoing aSAH surgery were randomized to receive either propofol (Group P) or desflurane (Group D). The cognitive functions were assessed using the Montreal Cognitive Assessment scale at three-time points- preoperatively, at discharge, and one 1month following surgery. Perioperative serum levels of S-100B were also measured.

Results: Preoperative mean cognitive score in Group P were 21.64 + 4.46 and in Group D was 21.66 + 4.07 (P-value- 0.79). At the time of discharge from the hospital, there was a decrease in mean cognitive scores (Group P- 20.91 + 3.94 and Group D-19.28 + 4.22, P-value- 0.09). One month following surgery, mean cognitive scores in Group P and Group D were 22.63+3.57 and 20.74+3.89 respectively (P=0.04). Higher memory and orientation scores were observed in Group P compared to Group D at one month. The serum S-100B levels were similar in both groups.

Conclusion: The mean cognitive scores at one month following surgery were higher with propofol compared to desflurane. On subgroup analysis, orientation and memory scores were better preserved with propofol.

[SNACC-30] Conditional neuronal deletion of miR-200c but not miR-181a is protective against experimental stroke in mice

Griffiths B, Stary C, Xu C. Stanford University School of Medicine, Stanford, California, United States

Introduction: Embolic stroke remains a leading cause of death and disability worldwide and a significant perioperative complication. Despite promising preclinical gene therapy trials, treatment options remain limited to thrombolysis or mechanical thombectomy, which carry significant contraindications and associated risks. Clinical failures of gene therapies may be due to upstream regulation by non-coding RNAs, and/or cell-type specific differences in gene expression. MicroRNAs (miRs) are non-coding RNAs that regulate the expression of downstream target genes, often in a cell-type specific manner. We have previously demonstrated that inhibition of either miR-181a (1) or miR-200c (2) with intracerebroventricular injection of antagomir is protective against experimental stroke in mice. In the present study we generated genetic mouse lines of inducible calcium calmodulin kinase II-alpha (CKII-alpha) neuronal miR-181a and miR-200c deletion to investigate whether the protective effect of their inhibition is cell-type specific.

Methods: Jackson Lab strains Mirc14tm1.1Czc/J, miR-181a and Mirc13tm1Mtm/Mmjax, miR-200c were crossed with the Jackson Lab tamoxifen-inducible Cre recombinase strain B6;129S6-Tg, CKII-alpha cre/ERT2, under the control of the CKII-alpha promoter to generate inducible CKII-alpha neuronal loss-of-function. Double-transgenic mice were identified with polymerase chain reaction. At age 8-10 weeks mice were randomized and treated with 0.1 mL (3 mg) or corn oil vehicle alone via oral gavage for 7 days prior to 1 hour of middle cerebral artery occlusion (MCAO) or sham surgery. Mice were assessed for gross motor function via 4-point neurological score at 24h and then sacrificed and brains processed for quantification of infarct volume via staining with 2,3,5-triphenyltetrazolium chloride (TTC, n=6). Separate animals (n=3) were sacrificed after tamoxifen/vehicle treatment and brains fixed for microscopic assessment of cell-type specific expression of miR-181a and miR-200c via combined fluorescent immunohistochemistry and in situ hybridization.

Results: Brains from tamoxifen treated mice exhibited select miR deletion in CKII-alpha neurons. Infarct volumes were significantly lower and neurological scores significantly improved in CKII-alpha/miR-200c mice pre-treated with tamoxifen versus vehicle alone. In contrast, no difference was observed in infarct volume or neurological score in CKII-alpha/miR-181a mice pre-treated with tamoxifen versus vehicle.

Conclusions: Inhibition of CKII-alpha neuronal miR-200c but not miR-181a was protective against experimental stroke, suggesting alternative cellular targets for the protective effect of miR-181a inhibition. Future studies should utilize alternative Cre-recombinase promotor strains to identify the functional cellular targets for miR-181a deletion, and in parallel investigate the direct miR-200c gene targets inCKII-alpha neurons to advance novel drug discovery for clinical stroke. Funding: American Heart Association grant 18POST33990395 to BGG and National Institutes of Health grant R01NS107445 to CMS.

[SNACC-31] Consequences on Recovery from Anesthesia in Global GABAα4 Knock-Out Mice

Graves M, Mohammad Mansouri S, Cassim T, Garcia P. Columbia University Medical Center

Introduction: The GABA Type A receptor (GABAAR) is important for mediating unconsciousness in clinical anesthesia. Monitoring of neurophysiologic signals via the electroencephalogram (EEG) during anesthesia can help identify characteristic patterns in sleep, general anesthesia, and coma. Burst suppression is a discontinuous EEG pattern typically seen with administration of excessive anesthesia but can also be observed in older patients that are receiving usual doses of analgo-sedative medication. It has been demonstrated previously that cortico-thalamic gabra4 gene knock-out mice under general anesthesia have emerged faster with inhaled anesthetics, this study was aimed at assessing GABA and non-GABAergic parenteral anesthetics and their role in recovery and emergence. Here we examine the role of a specific subtype of GABAAR (α4-containing) in the relationship of drug choice and anesthetic dose with burst suppression.

Methods: Age-matched, adult male (26-30 g) mice genetically manipulated to knock-out (KO) the gabra4 gene and wild-type (WT) littermates were used. A total of 30 mice were used for this experiment. Following the administration of ketamine/xylazine (K/X, 90/5 mg/kg, intraperitoneal injection) and propofol (200 mg/kg, intraperitoneal), sub-dermal needle electrodes were applied, and electrophysiology was recorded wirelessly using an OpenBCI™ Cyton board. The collected data were analyzed using custom scripts written in MATLAB. These EEG changes were also associated with behavioral changes that were also examined. Statistical analysis was performed using un-paired t-test with GraphPad Prism.

Results: With a statistically significant change in RORR (P<0.0001) for the GABRA4 knock out mice in both the ketamine/xylazine and propofol group. We demonstrated that genetic ablation of GABRA4 results in variable EEG patterns for intraperitoneal injection of ketamine/xylazine and/or propofol/sham vehicle.

Discussion: It was demonstrated that the RORR for the GABA alpha4 KO was hastened in both the ketamine/xylazine and propofol group similar to the findings with inhaled anesthetics in previous studies. We conclude that there are important differences in thalamocortical neurophysiology mediated by α4-containing GABAARs. This suggest that the thalamc-cortical influences on emergence are important for both GABAergic and non-GABAergic regimens. These findings may be important to consider during the titration of analgo-sedative agents in clinical scenarios (Fig. 1 and 2).

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FIGURE 1
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FIGURE 2

[SNACC-32] Criticality Across Altered States of Consciousness: A Scoping Review

Gervais C*, Boucher L*, Martinez Villar G*, Lee U, Duclos C*. Université de Montréal, Montréal, Quebec, Canada*. University of Michigan, Ann Arbor, Michigan, United States

While the healthy conscious brain has been shown to operate in a critical state, which tunes the functional brain network to maximal information content and susceptibility to perturbations, deviations from the critical state are hypothesized to give rise to altered states of consciousness (ASC). Measures of criticality could therefore be an effective way of characterizing consciousness and the functional underpinnings of various ASC. We undertook a scoping review of the evidence for deviations from the critical state in ASC. Two databases (Web of Science, PubMed) were searched from inception to the 7th of February 2022 to find articles relating to measures of criticality across different ASC. A total of N=427 independent papers were initially found on the subject. N=366 were excluded because they were either: not related to criticality; not related to consciousness; not presenting results from a primary study; not measuring criticality in humans or animals. N=61 independent papers were included in the present research, separated in 7 sub-categories of ASC: disorders of consciousness (DOC) including coma, vegetative state and minimally conscious state (n=5); sleep (n=15); anesthesia (n=18); epilepsy (n=14); psychedelics and shamanic state of consciousness (n=4); delirium (n=1); meditative state (n=4). Each category of ASC included articles suggesting a deviation of the critical state. This scoping review suggests that ASC are characterized by a deviation from criticality when compared to normal waking consciousness, though several studies fail to establish the direction of this deviation. The preliminary consensus arising from the literature is that anesthesia and DOC are sub-critical states, epilepsy is a super-critical state, and psychedelics are closer to the critical state than normal consciousness. These results suggest that criticality could become, with more extensive research, an effective and objective way to characterize consciousness and its alterations, ultimately leading to improved diagnosis in ASC. In turn, this could meaningfully contribute to clinical management and decision-making, particularly for unresponsive patients in acute care. Further characterization of criticality properties in ASC could help identify therapeutic targets for the restoration of criticality in pathological ASC, paving the way for accessible and effective treatments that modify the functional properties of the brain network.

[SNACC-33] CXCL8 Expression In Patients With Cerebral Vasospasm Following Aneurysmal Subarachnoid Hemorrhage

Bhagat H, Kumar M. Postgraduate Institute of Medical Education and Research, Chandigarh, India

Background: Cerebral vasospasm is a pathophysiological condition which commonly occurs following aneurysmal subarachnoid haemorrhage (aSAH). Symptomatic vasospasm leads to ischemic brain injury contributing significantly to morbidity and mortality. Inflammation plays a significant role in the development of cerebral vasospasm. The overexpression of inflammatory mediators such as TNF-α, IL-6 and MCP-1 etc. has been reported after aSAH. However, CXCL8 an inflammatory cytokine has not been well studied. CXCL8 is known to regulate the expression of molecules such as MCP-1 and MMP9 which have been implicated in the pathogenesis of cerebral vasospasm. We hypothesize that CXCL8 may play important role in the development of cerebral vasospasm.

Methods: Following Institutional Ethical Committee approval, the patients with ruptured intracranial aneurysm without vasospasm and those with vasospasm confirmed through CT scan and angiography were included in the study. Blood samples were collected preoperatively while aneurysmal wall tissue samples were collected intraoperatively during the course of aneurysm clipping. RNA was extracted from tissue samples and qRT-PCR was performed to check the expression of CXCL8 at transcript level. Serum was separated from blood samples and ELISA was performed to check the expression of CXCL8 at protein level.

Results: 33 tissue samples (22 without vasospasm and 11 with vasospasm) and 56 serum samples (31 without vasospasm and 25 with vasospasm) were analysed to check the expression of CXCL8. We observed the over-expression of CXCL8 at both transcript (5.06-fold) and protein level (1.89 fold) in the patients with vasospasm compared to those without vasospasm.

Conclusions: The study demonstrates that there is overexpression of CXCL8 at both transcript and protein level in patients with vasospasm. The elevated expression of CXCL8 may be important for the development of cerebral vasospasm after aneurysmal subarachnoid haemorrhage. CXCL8 can serve as a potential biomarker for cerebral vasospasm which needs to be validated further in a bigger patient cohort.

[SNACC-34] Degradation of Intraoperative Motor Evoked Potentials following Bilateral Erector Spinae Plane Blocks in Lumbar Spine Surgery – a case report

Acharya P, Ma K, Ruiz C, Witiw C. St. Michael’s Hospital, University of Toronto, Toronto, Ontario, Canada

Introduction: Erector spinae plane (ESP) block has gained popularity as an opioid-sparing analgesic modality for thoracolumbar spine surgery in recent years1. Its analgesic effect is thought to be related to the local anesthetic (LA) mediated blockade of dorsal rami branches and systemic LA absorption. Nonetheless, evidence from cadaver studies and case reports suggest that the undesirably extensive spread of LA may result in the motor blockade, and thus the concern was raised regarding its compatibility with intraoperative motor evoked potential (MEP)2,3. We hereby present a case involving the transient loss of bilateral lower-extremity (LE) MEPs loss following lumbar ESP blocks in lumbar spine surgery. Case summary: A 50-year-old man with L3-L5 spinal stenosis was presented for an elective L3-L5 posterior decompression and instrumented fusion. Preoperative examination revealed 5/5 motor strength in all extremities with no sensory deficit. After the induction of general anesthesia with propofol, remifentanil, and rocuronium 25 mg, the patient was maintained on propofol, sufentanil, and ketamine infusions. With the patient in the prone position, bilateral ultrasound-guided ESP blocks, each with 30 mL of Ropivacaine 0.2%, were performed at the L4 vertebrae using a 22G needle via an in-plane approach. A good injectate spread was noted on the ultrasound. Baseline MEP was obtained immediately following the ESP blocks, approximately 45 minutes after rocuronium administration. The initial MEP demonstrated the presence of robust signals at Adductor Digiti Minimi (ADM) and Rectus Femoris (RF) bilaterally, but signals were absent from bilateral Tibialis Anterior, Extensor Hallucis Longus, and Gastrocnemius and left Abductor Hallucis Longus (AHL) (Fig. 1). The right AHL MEP, though present initially, deteriorated over the next 8 minutes following the ESP block. MEPs were repeated over the next two hours of surgical exposure, and prior to the start of lumbar decompression, robust MEPs were obtained at all LE muscles where there previously had no baseline signals. This also included the reappearance of the right AHL MEPs, which were initially noted to have disappeared shortly after the ESP blocks. The remainder of the surgery was otherwise uneventful. Following extubation, the patient exhibited 5/5 power in all 4 extremities with no deficits, and the patient was eventually discharged home in stable condition.

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FIGURE 1

Discussion: To our knowledge, this is the first documentation of intraoperative MEP changes following bilateral lumbar ESP blocks. The initial presence of ADM and RF MEPs suggested that neither physiological nor pharmacological factors could have accounted for the initial absence of LE MEPs. The eventual appearance of robust LE MEPs occurred prior to lumbar decompression, thereby ruling out spinal cord compression as the culprit. While ESP block is described primarily as a sensory block, cadaver studies have demonstrated that injectate can spread in craniocaudal, anteroposterior, and lateral-to-medial planes encompassing the neural foramen, paravertebral space, and epidural space2. The extensive LA spread and its resultant involvement of the ventral rami could have accounted for the transient loss of bilateral LE MEPs in this case. While there has been a case report of transient postoperative paraplegia attributed to ESP blocks, our case is the first to present evidence of intraoperative MEP changes related to the ESP blocks. In light of this, the potential benefits of ESP blocks should be carefully weighed against their undesirable side effects in scenarios where intraoperative MEP is indicated. Keywords: Bilateral Erector Spinae Plane Blocks, Intraoperative Motor Evoked Potentials, Neuromonitoring.

[SNACC-35] Deuterium Magnetic Resonance Imaging for Evaluation of Glymphatic Flow

Hunt R, Nagaraja T, Ding G, Knight R, Lee I, Ewing J, Penning D. Henry Ford Health System, Detroit, Michigan, United States

Background: In the 1905s, intraventricular deuterium (D2O) was used to study the absorption of cerebrospinal fluid (CSF) into the venous system in hydrocephalic children. Studies were limited by the lack of available methods to image the movement of D2O in the brain. The exact route by which CSF returns to the venous system has not yet been fully elucidated. More recently, the role of the glymphatic system has been defined and explored using tracers such as gadolinium to track the movement of CSF through the perivascular spaces and into the brain interstitium. Mathematical models of CSF movement into and out of the brain interstitium have not been consistent with observed behavior. A recent study using an isotope of water (H2-170) showed significantly increased rate of CSF flow into the glymphatic system as compared to a traditional gadolinium tracer. This difference may reasonably be explained by the fact that gadolinium is not blood-brain-barrier (BBB) soluble. Because the primary component of CSF is water, CSF likely behaves quite differently than many of the tracers historically used to track its flow. Due to both expense and toxicity profile, H2-170 is not an ideal tracer for translational studies. Recently, D2O-labeled glucose has been shown to produce a detectable magnetic resonance (MR) signal, suggesting D2O may hold promise as an imageable tracer for glymphatic studies.

We hypothesized that D2O would provide a traceable MR signal for tracking movement of water in the brain, allowing for more physiologically realistic models of CSF flow within the glymphatic system.

Methods: Two adult male rats underwent deuterium enhanced MR imaging. Images were obtained using a custom-made RF transmit/receive coil from Rapid MR International that is dual tuned to both proton (1H, 300.3 MHz) and deuterium (2H, 46.1 MHz) resonant frequencies for use in a 7 Tesla Bruker MRI system. The coil itself consists of two separate resonant circuits with the proton coil using a butterfly design and the deuterium coil a 25 mm loop design with both circuits rated for 400 W maximum RF peak power. After prepping the animal, it was placed prone in a non-magnetic cradle, the 1H/2H coil was positioned over the head and entire setup will be moved into the MRI system. The proton coil was set first to set up for the proton frequency, adjusting magnetic field homogeneity, and to provide high-resolution reference images. Following the proton imaging, the system frequency was switched over for the deuterium coil before starting the D2O infusion. Images from the D20 signal were acquired 30 seconds after starting intravenous infusion of deuterated saline. Continuous infusion of deuterated saline was continued for 12 minutes with MRI images every two minutes to track the uptake and clearance of the deuterium signal.

Results: Deuterium produced a traceable MR signal in the brain after intravenous injection (Figure 1 and 2).

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FIGURE 1:
Baseline proton image.
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FIGURE 2:
Deuterium Image.

Conclusion: Deuterium MRI holds promise as a novel CSF tracer. Next steps include intrathecal infusion of D2O via spinal catheter with concurrent proton and deuterium MR imaging.

[SNACC-36] Development and Implementation of de-novo Intraoperative Neuromonitoring Program in Uganda Utilizing the EPIS Implementation Framework

Montejano J*, Simmons C*, Clavijo C*, Nantonogo B, Teguo D, Wegoye E. University of Colorado School of Medicine, Aurora, Colorado, United States*. CURE Uganda, Mbale, Uganda. Harvard, Boston, Massachusetts, United States

Introduction: Over the past two decades the use of Intraoperative Neuromonitoring (IONM) has become increasingly common globally, especially as monitoring modalities have become more reliable. Access to IONM services in low-income countries is limited due to cost, availability of equipment and personnel with the expertise to administer and interpret IONM during neurosurgical procedures. According to the WHO, up to 80% of chronically disabling conditions worldwide are neurological in origin which could require surgical intervention. Although imperfect, IONM is currently the only way to monitor spinal cord function under general anesthesia. Surgical intervention without continuous monitoring is fraught with potential complications and can lead to permanent patient harm resulting in severe disability. In resource limited countries, this can impact lifelong productivity and survivability. Even without conclusive evidence that IONM is absolutely necessary for neurosurgical procedures an argument can be made that given the potential to positively impact a patient’s life, it is a worthwhile pursuit. There is a significant need for formal training of neuromonitoring technicians and anesthesiologists to safely administer and interpret IONM. Here we recount the experience we had in developing and implementing an IONM program using the EPIS framework in Mbale, Uganda, where the first reported surgical procedure utilizing IONM in the country was performed.

Methods: The implementation of IONM in Uganda was undertaken utilizing the EPIS Framework. Exploration: Survey trip performed, and preliminary meetings held with CURE Children’s Hospital Uganda. Needs assessment revealed ~1200 neurosurgical procedures performed annually, with >5% warranting utilization of IONM. A strong desire by surgical and hospital leadership to create and implement an IONM program in line with ABRET standards. Preparation: Monthly meetings held virtually with all stakeholders present. Meetings discussed allocation of consumable resources, securement of technical equipment, selection of technical personnel, etc. A local and qualified trainee was selected and online training of basic aspects of IONM commenced 3-months prior to planned implementation. Weekly discussions and case-simulations were carried out.

Implementation: A case-simulation was carried out with newly trained IONM Technologist and surgical team prior to the first live case. A CNIM Technologist and an ABA board certified Anesthesiologist with IONM training were present for one week to train and teach the staff in Mbale. Three total cases were completed during the week.

Sustainment: Ongoing collaboration exists in the form of virtual case conferences. Monthly support including formal lectures, access to training and simulations, and technical support. In addition, the Global Anesthesia program within the Department of Anesthesiology at University of Colorado has formalized a relationship with CURE Uganda and provides support via service trips and resource allocation.

Results: During the first week of the newly implemented IONM program three cases were performed including a spinal cord detethering, a posterior fossa craniotomy for tumor resection and sensory evoked potentials used to rule-out brain death in a critically ill patient. Each monitored case resulted in adequate signal acquisition of all modalities employed: MEP, SSEP, EMG and tEMG. Technical troubleshooting by trainees demonstrated continued need for oversight, but progression toward independent practice.

Conclusion: The burden of neurosurgical disease worldwide is great. The role of IONM in preventing catastrophic neurological outcomes is well established in developed countries. In this project, we demonstrate a framework for the implementation of an IONM program. Early results demonstrate its effectiveness and utility. Future collaborations should be sought to offer this life-changing technology to societies that could benefit the most from this intervention. Furthermore, we conclude that sustainable change and mutual benefit can be achieved when North-South collaborations seek to achieve equity in their outcomes.

[SNACC-37] Dexmedetomidine in the Treatment of Serotonin Syndrome

Khromava M, Kor T. Mayo Clinic, Rochester, Minnesota, United States

Serotonin syndrome is a potentially life-threatening condition often described as a clinical triad of cognitive, autonomic, and somatic abnormalities. Symptom onset is usually rapid, and the degree of symptoms can range from mild to severe, including hypertension, tachycardia, hyperthermia, agitation, hyperreflexia, tremor, sweating, mydriasis, diarrhea, seizures, and coma (1).

A 67-year-old male with past medical history of obstructive sleep apnea, hyperlipidemia, hypertension, and migraine was admitted for lumbar fusion in the setting of lumbar spinal stenosis with neurogenic claudication. His home medications included nortriptyline and verapamil. The patient underwent a standard induction with fentanyl, lidocaine, propofol, and succinylcholine. Total intravenous anesthesia was maintained with propofol and sufentanil. Surgical paralysis was achieved with rocuronium. The patient also required phenylephrine infusion and intermittent ephedrine administration for pressure support. Other administered medications included ondansetron, sugammadex, dexamethasone, cefazolin, tranexamic acid, and caffeine. His intraoperative course was unremarkable from a surgical perspective. The patient was extubated at the end of the procedure and taken to the post-anesthesia recovery unit. While in the recovery room, the patient demonstrated significant autonomic excitation. He was tachycardic to 120s-130s and had elevated blood pressure (with systolic blood pressure in 190s). He had a temperature of 37.5°C as measured with the hand-held thermometer. The patient was alert but not oriented. He was not able to follow commands and appeared very anxious and restless. Bilateral horizontal nystagmus and bilateral myoclonus in both upper and lower extremities were noted on the neurologic exam. Serotonin syndrome was suspected, and the patient received two doses of diazepam without any significant changes in his vital signs or physical exam. The patient also received a dose of physostigmine to rule out anti-muscarinic toxicity which also did not improve his presentation. Next, 80 mcg of Precedex was administered over the course of 45 minutes via four 20 mcg boluses. The patient’s vital signs stabilized. His myoclonus and nystagmus resolved. The change in his presentation was drastic. The patient started following commands and answering questions. He was subsequently admitted to the intensive care unit (ICU) for observation. The patient was discharged from the ICU the next day without any additional interventions.

Serotonin syndrome symptoms can range from mild to life-threatening and are thought to be mediated by excessive stimulation of the 5HT-1a and 5HT-2a receptors. Diagnostic Hunter criteria define the syndrome as the presence of clonus in the setting of a serotonergic agent administration (1). Administration of benzodiazepines is considered the first-line treatment of serotonin syndrome. However, management of serotonin syndrome may be refractory to the treatment with benzodiazepines alone. There are only a few case reports and no human studies describing the treatment of serotonin syndrome with dexmedetomidine (1,2). Studies in rats show that dexmedetomidine may be more beneficial than benzodiazepines in the treatment of serotonin syndrome (3). Our patient showed a significant clinical improvement after the administration of dexmedetomidine, as reflected by improvement in tachycardia, myoclonus, and mental status. Dexmedetomidine treatment of serotonin syndrome can be considered in refractory cases and calls for more investigation.

[SNACC-38] Does the presence of intracranial steno-occlusive disease alter the resting PCo2? - A prospective observational study

Agrawal S, Chowdhury T, Fisher J, Mikulis D, Sobczyk O, Venkatraghvan L. Toronto Western Hospital, Toronto

Background: Carbon dioxide is a potent cerebral vasoactive stimulus and the adjustment of PCO2 is commonly employed for the close regulation of intracranial pressure during the various neurosurgical procedures. The normal resting PCO2 is usually considered as 35-45(1). Interestingly, in patients with intracranial steno-occlusive disease (IC-SOD), hypercapnia often causes intracerebral steal phenomenon (diversion of blood from stenotic region to normal brain region leading to relative cerebral ischemia). Our team has observed that in many patients with IC-SOD, the resting PCO2 values vary substantially. Therefore, the aim of this study was to determine the resting PCO2 levels pre and postoperatively in patients with IC-SOD.

Methods: After the REB approval, we conducted a prospective observational study in all patients with IC-SOD who were scheduled to undergo cerebrovascular reactivity (CVR) measurements for comprehensive clinical management. CVR measurements were performed using a well-controlled end-tidal CO2 (PETCO2) using a computerized gas blender and sequential breathing circuit (RespirAct). “RespirAct” eliminates dead space, thereby the measured PETCO2 equals arterial CO2 (PaCO2)(2,3). We collected the resting PETCO2 values from all patients with symptomatic IC-SOD who demonstrated intracranial steal phenomenon. In addition, subset of patients who had revascularization surgery, we collected pre and post revascularization PETCO2 values. Data were analyzed descriptively.

Results: Out of 255 patients, 135 had atherosclerosis (ICAD), 83 with Moya-Moya disease (MMD), 30 had Moya-Moya syndrome (MMS) and 07 had other pathologies (Vasculitis, dissection, sickle cell disease, stroke). The resting PCO2 for all patients were noted to be in the range of 24 to 50, with the mean of 37.5. The average resting PCO2 for patients with MMD was 37.7, MMS was 37.8, ICAD 37.3, and 38.2 in others In addition, the resting PCO2 range post bypass surgery (n=45) was found to be 24-47 mm hg (mean of 38.6 mm Hg). As compared with the pre-op resting PCO2, the post bypass values for all patients were found to be slightly higher.

Conclusion: Patients with intracranial steno-occlusive disease often present with deranged cerebral autoregulation either due to the inadequate cerebrovascular reactivity or the presence of intracranial steal phenomenon. Our study highlighted that a wide range of resting PCO2 (24-50) can be expected in such cases. In addition, there are slight trends towards normalization of resting PCO2 post bypass. The knowledge of resting PCO2 value is important for the perioperative physicians in regulating the cerebrovascular physiology tightly, and may assist in avoiding the steal phenomenon intraoperatively.

[SNACC-39] Effect of crystalloids or colloids on coagulation profile in patients undergoing craniotomy

Gowda P. PGIMER, Chandigarh, India

Background: Blood loss in patients undergoing craniotomy for neurosurgical pathology is usually replaced by isotonic crystalloid, colloids, blood and blood products which restore blood pressure and blood volume. The use of colloids may decrease the fluid requirement during intraoperative major blood loss. Hence, it was planned to compare the effect of intraoperative resuscitation using crystalloid (Plasmalyte) and a combination of crystalloids with colloids (6% HES 130/0.4 with electrolytes) intraoperatively during craniectomy for neurosurgical pathology. The primary outcome of the study was to compare the change in coagulation parameters from baseline and at the end of surgery using Sonoclot in both the groups. The secondary outcomes were to compare intraoperatively hemodynamics, brain relaxation score at the opening of the dura and the end of surgery, total blood loss, Intraoperative total fluid volume, Blood and blood products, serum lactate levels/ serum electrolytes, renal functions 24 hours and 48 hours after surgery (Serum Cystatin-C levels and AKIN criteria), and outcome at discharge by Modified Rankin Scale (MRS).

Materials and Methods: Prospective, Randomized, double-blinded controlled trial was designed and a total of 107 patients were allotted into 2 groups: Group Cs and Group Co who received intra-operative crystalloids and a combination of Colloid with crystalloids respectively. Intraoperatively blood sample was collected for Sonoclot analysis at the start of the surgery and at the end of surgery for ABG with serum electrolyte and lactate levels was performed at baseline, at the start of blood loss, at MABL and at the end of surgery. Vitals, urine output, total blood loss, amount of colloids/ crystalloids used, urine output, use of vasoactive drugs and Brain Relaxation Score (BRS) were monitored and recorded. Postoperatively patients were followed up to 48 hours for the signs of renal dysfunction by monitoring serum creatinine, Cystatin – C and urine output. The total duration of hospital stay, postoperative complications and neurological outcome was assessed the time of discharge using MRS,

Results: There were no significant differences between both the groups in coagulation parameters, BRS, ABG values, amount of blood loss or transfusion, serum electrolyte and lactate levels, renal functions, post operative complications, days of hospital stay and outcome at discharge with P values >0.05. There was lesser fluid requirement (P<0.001), lower requirement of vasopressors boluses (P<0.001) to maintain haemodynamic stability in colloid group as compared to crystalloid group

Conclusion: Intraoperative use of low dose modern Hydroxyethyl starches did not affect the coagulation parameters, brain relaxation scores, intraoperative blood loss, blood transfusion requirement, serum electrolyte and lactate levels and did not alter the renal functions with comparable outcome a discharge in patients undergoing elective craniotomy for neurosurgical pathology as compared to crystalloid. The use of colloids reduced the requirement of crystalloids and total intraoperative fluid to maintain stable haemodynamics.

[SNACC-40] Effect of First Anesthesia Exposure on Short-Term Neurocognitive Function in Children between Ages 1-36 Months: a Case-Control Pilot Study

Waitayawinyu P, Kiatchai T, Kiatpanomphae T, Gosiyaphant N, Rattana-arpa S, Jindawatthana I, Buasuk T, Rojmahamongkol P, Sutchritpongsa S. Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok

Background: Multiple human evidences have shown no significant result of anesthesia exposure during early childhood on long-term academic achievement or general intelligence compared with general population. Studies in short-term neurodevelopmental assessment were limited, mostly conducted in pre-existing neurological condition such as craniosynostosis surgery, or shortly after complex cardiac surgery that patients were at risk to cerebral hypoxia during cardiopulmonary bypass. This study aims to evaluate (1) short-term characteristics of neurocognitive function after anesthesia in non-cardiac surgery compared with baseline, and (2) differences of baseline neurocognitive function between sick children requiring anesthesia and healthy Thai infants and toddlers.

Methods: This prospective case-control pilot study was conducted in the Faculty of Medicine Siriraj Hospital during November 2017 – November 2019. We recruited 20 healthy participants for control group from Siriraj Daycare and 40 participants for anesthesia group from Siriraj Hospital. Children aged between 1-36 months without previous anesthesia were included. We excluded children who was born at less than 37 weeks of gestation, known developmental delay, neurological disease, and maternal exposure to neurotoxicity agent. Neurocognitive function was assessed by one of the two pediatric psychologists using the Bayley Scales of Infant and Toddler Development, third edition. The cognitive scale is comprised of 91 items, which assess memory, problem solving and manipulation. Baseline assessment was done in both groups. Post-anesthesia assessment was done at 7-day after operation in anesthesia group. Cognitive composite score has a mean of 100 and a standard deviation (SD) of 15 in which a difference of score >1/3 SD (5 points) was defined as clinical significance. Participants who had post-anesthesia cognitive composite score lower than baseline more than 5 points were considered in the declined group. Cognitive composite score below 85 is considered cognitive delay. Descriptive statistics were used to describe demographic data. Mann-Whitney U test was used to compare age, Student’s t-test was used to compare cognitive scale between two groups.

Results: In control group, 20 participants received baseline assessment. In anesthesia group, 47 participants received baseline assessment and 39 participants received post-anesthesia assessment. Participants in control group were significantly older than anesthesia group. Median (P25-P75) ages in control and anesthesia group were 16.5 (10.2-28.2) and 8.3 (4.1-14.2) months, P-value 0.005. Baseline cognitive scale of anesthesia group was statistically and clinically lower than control group. Mean (SD) cognitive composite score in control and anesthesia group were 111.50 (11.71) and 97.13 (9.88), P-value <0.001. Mean difference (95% CI) was 14.37 (8.28-20.47). Four (8.5%) participants in anesthesia group had cognitive delay pre-operatively. Among 39 participants in anesthesia group who received both baseline and post-anesthesia assessment, clinical difference in cognitive composite score cannot be concluded (mean difference [95% CI] 4.23 [0.23-8.23]). Mean (SD) of baseline and post-anesthesia cognitive composite score was 97.05 (9.85) and 101.28 (10.87), P-value 0.039. Seven (18%) participants were considered in the declined group. Three (7.7%) participants had post-anesthesia cognitive composite score lower than baseline >15 points or 1 SD. Mean difference (95% CI) of cognitive composite score between baseline and post-anesthesia assessment in declined group was −13.57 (−17.97 to −9.17).

Conclusions: Children in anesthesia group had lower baseline cognitive composite score than control group. Anesthetic exposure resulted in declined cognitive composite score in 18% of participants (Fig. 1).

F21
FIGURE 1:
Mean differences (95% confidence interval) between baseline and post-anesthesia cognitive composite score in anesthesia group (N=39).

[SNACC-41] Effect of intraoperative muscle relaxation reversal on the success rate of motor-evoked potential recording in patients undergoing spinal surgery: a randomized controlled trial

Jian M, Han R, Liu H, Ma B, Zhou Y, Wang C, Liang F. Beijing Tiantan Hospital, Beijing, China

Introduction: The optimal regimen of neuromuscular blockade for Transcranial motor-evoked potentials (TceMEPs) monitoring has not been established. Partial neuromuscular blockade (NMB) has been applied for some surgeries to reduce bleeding and prevent patient movement. Sugammadex selectively binds to rocuronium at the neuromuscular junction and rapidly reverse NMB. In this study, we aim to observe whether the success rate of TceMEPs can be increased by sugammadex comparing with partial NMB during spinal surgery.

Methods: This is a single-center, prospective, parallel-group, assessor-blinded randomized controlled study. 162 patients underwent elective spinal surgery with TceMEPs monitoring randomly assigned to sugammadex group and control group at a ratio of 1:1. The closed-loop neuromuscular blockade infusion system was used for continuous infusion of rocuronium in both groups during the operation to maintain the train of four count (TOFc)=2. The sugammadex group discontinued rocuronium infusion at the time of TceMEPs monitoring and infused 2 mg/kg sugammadex; the control group discontinued rocuronium infusion at the time of TceMEPs monitoring and infused the same dose of saline. The primary outcome of the study was the success rate of monitoring in the two groups 5 minutes after the first performing of TceMEPs. Secondary outcome included the average amplitude of TceMEPs in both upper extremities 5, 10, 20, 30, and 60 minutes after the first performing of TceMEPs the incidence of intraoperative movement, and adverse effects caused by sugammadex, etc.

Results: 162 patients were included for the study. The success rate of TceMEPs monitoring in the sugammadex group was significantly higher than control group (95.9% vs. 82.0%, P=0.028). TceMEP amplitudes were significantly greater in the sugammadex group than in the control group (P=0.033) at 5 minutes after the start of TceMEPs monitoring. TceMEP amplitudes were also greater in the sugammadex group at 10 minutes (P=0.039), 20 minutes (P=0.003), 30 minutes (P=0.041), and 60 minutes (P=0.023) after the start of TceMEPs monitoring. The incidence of intraoperative movement showed no significant difference between two groups. There were none adverse effects caused by sugammadex in our study.

Conclusions: Sugammadex can improve the success rate of TceMEPs monitoring comparing with moderate neuromuscular blockade induced by continuous infusion of rocuronium in spinal surgery. Our study suggests that sugammadex can be used to reverse neuromuscular blockade and enhance TceMEPs monitoring during spinal surgery.

[SNACC-42] Effect of Propofol and Dexmedetomidine Infusion on Blood Glucose Levels and Hemodynamic Response during Skull pin Insertion in Intracranial Tumor Surgeries : A Randomized Trial

Varda R, Swaro S, Mohapatra S. Institute of Medical Sciences and SUM Hospital, Bhubaneswar, India

Background: Mayfield Skull pin application during craniotomy for adequate surgical access and position stability would cause significant periosteal stimulation resulting in surge of heart rate, blood pressure, blood glucose and intracranial tension which disrupts intracranial milieu. Persistence of such metabolic stress can lead to cerebral ischemia, cerebral edema, increasing post-operative morbidity and mortality. We compared the efficacy of Propofol and Dexmedetomidine infusion in attenuating blood glucose and hemodynamic response to the skull pin application Objectives: To determine and compare the effect of Propofol infusion and Dexmedetomidine infusion on blood glucose levels during skull pin insertion. To determine and compare the hemodynamic response after Propofol infusion and Dexmedetomidine infusion during skull pin insertion

Methods: Design: A randomized, double blinded (patient and investigator blinded), parallel group, prospective single centric study conducted in Institute of Medical Sciences and SUM hospital, Bhubaneswar, India Computer generated randomization of 80 American Society of Anaesthesiology grade I & II patients (Group P n=40; Group D n=40) aged between 18-60 who are undergoing elective intracranial tumor excision under general anaesthesia

Interventions: Propofol infusion 150 mcg/kg/min IV (Group P) versus bolus of 1 mcg/kg of Dexmedetomidine for 10 minutes followed by infusion of 0.5 mcg/kg/h (Group D) Patients were monitored for the blood glucose levels by hemo-glucose testing using glucometer; Haemodynamic changes like Heart rate, Systolic Blood pressure, Diastolic blood pressure, Mean arterial pressure during and after skull pin insertion were noted; Outcome: Attenuation of stress response during skull pin insertion by indirect stress markers like glucose and hemodynamic parameters

Results: Blood glucose levels, Heart rate, Systolic Blood pressure, Diastolic blood pressure, Mean arterial pressure were compared between two groups at baseline and before pin insertion. The mean percentage variation of HGT (hemo glucose testing) after 40 minutes of pinning was 18.3% in group D and 12.75% in group P which is statistically non-significant. Control of hemodynamic parameters was better in Group P than Group D at 5 minute of insertion with P value of <0.001, 0.017, <0.001 respectively for Systolic, Diastolic blood pressure and Mean arterial pressure

Conclusion: Propofol infusion is superior to Dexmedetomidine infusion in regulating blood glucose levels and attenuating hemodynamic stress response after skull pin insertion.

Trial Registration: Institutional ethics committee approval: Ref.No./DMR/IMS.SH/SOA/180350”

Clinical trials registry- India CTRI/2021/03/031948 [Registered on: 12/03/2021]

[SNACC-43] Effects of Desflurane on the Quality of Anesthesia Recovery Period in Patients Undergoing Endonasal Endoscopic Pituitary Adenoma Resection: A Randomized Controlled Study

Fu Y, Yu Y, Cui Y, Zhou Y, Sun W, Han R. Beijing Tiantan Hospital, Capital Medical University, Beijing, China

Background: Pituitary adenomas are the most common space-occupying lesions in the sella turcica. High-quality anesthesia recovery period is helpful for early postoperative neurological function assessment in patients with pituitary tumor, and reduces the risk of aspiration, hypoxemia, and sleep apnea during perioperative period. Desflurane is one of the third-generation inhalation halogen anesthetics, which has the lowest blood gas distribution coefficient and the lowest lipophilia. Desflurane restores the protective swallowing reflex more quickly than using sevoflurane or propofol. The purpose of this study was to compare the quality of anesthesia recovery in patients undergoing endoscopic pituitary adenoma resection with desflurane inhalation anesthesia versus propofol intravenous anesthesia.

Methods: In this randomized, single-blind, parallel, controlled study, we enrolled patients aged 18-65 years, with ASA I–III, who were scheduled to undergo endonasal endoscopic pituitary adenoma resection. Patients were randomly assigned in a 1:1 ratio to receive desflurane-remifentanil or propofol-remifentanil anesthesia. The primary outcome was the time it took for patients to reach an Aldrete score of 9 after discontinuing all anesthetic. Secondary outcomes included the incidence of agitation, the incidence of hypoxemia during anesthesia recovery and the incidence of vomiting within 2 hours after surgery. Riker sedation and agitation score was used to evaluate agitation. More than four points is considered to be agitation. Hypoxemia during anesthesia recovery was defined as blood oxygen saturation less than 95% without oxygen inhalation within 10 minutes after tracheal intubation removal.

Results: Of 127 patients who were assessed for eligibility, 112 were randomized and included in the modified intention-to-treat analysis, with 56 patients in each group. The time it took for patients to reach an Aldrete score of 9 after discontinuing all anesthetic in desflurane group was shorter than propofol group: 13.0 [11.0-17.0] min in desflurane group and 16.5 [12.3-22.0] min in propofol group (P=0.003). The per-protocol analysis yielded a similar result: 14.0 [10.8-17.5] min in desflurane group and 16.0 [12.0-22.0] min in propofol group (P=0.013). The incidence of agitation was lower in the propofol group: 3.6% in propofol group and 17.9% in desflurane group (RR: 0.852, 95% CI: 0.746-0.972; P=0.015). The incidence of hypoxemia during anesthesia recovery was similar between the two groups: 16.1% in desflurane group and 17.9% in propofol group (RR: 0.884, 95% CI: 0.389-2.007; P=0.768). The incidence of vomiting within 2 hours after surgery was 19.6% in desflurane group and 5.4% in propofol group (RR: 3.600, 95% CI:1.063-12.196; P=0.024).

Conclusions: For patients undergoing endonasal endoscopic pituitary adenoma resection, desflurane-remifentanil anesthesia can improve the quality of anesthesia recovery. But desflurane increases the risk of perioperative agitation in obese patients.

[SNACC-44] Electroencephalography Characteristics of Neurosurgery Patients in Different Consciousness States Induced by Propofol

Yang W, Han R, Li M, Lin N, Liu X, Liu H, Wang X. Beijing Tiantan Hospital, Capital Medical University, Beijing, China

Background: The evaluation of various types of neurological function is often aided in the perioperative management of glioma patients to help physicians keep abreast of changes in the patient’s condition and to maximize the protection of the patient’s neurological integrity. Neurological deficits caused by gliomas may be hidden due to neuronal reorganization near these brain regions, sedation induced by γ-aminobutyric acid receptor activation may reveal the abovementioned neurological damage. But the mesoscopic level evidence that sedative drugs affect the transmission of information about activity in the brain is lacking. EEG is currently a more sensitive index for monitoring brain function and allows for the mesoscopic-level elaboration of changes in central nervous system messaging networks. The study investigated whether EEG features differed between patients with and without intracranial lesions, especially during sedation.

Methods: The purpose of this prospective, exploratory, and observational study was to collect EEG signals under different levels of propofol-induced sedation. Sixteen patients with frontal lobe supratentorial gliomas and sixteen patients without intracranial lesions were recruited, and analyzed for Patient State Index, EEG spectrum, and functional connection. Based on functional connectivity coherence analysis, principal component analysis and k-means clustering algorithm were used to identify potential metastable states.

Results: A total of 32 patients were enrolled in this study. There were no significant differences were found in the baseline characteristics between the two groups, including functional status scores and patient sedation status index. There was no significant difference in the EEG power values between the two groups of patients under different sedation states. In the functional connectivity analysis, compared with the control group, there were significant decreases in beta connectivity during light sedation (OAA/S=3: beta: glioma group: 0.78±0.04, control group: 0.83±0.03, P=0.005) and deep sedation (OAA/S=1: beta: glioma group: 0.80±0.03, control group: 0.85±0.03, P =0.004) on the non-occupied side of the brain in the glioma group, and this difference did not exist during awake. Combined with EEG coherence metastable -states analysis, it was found that patients in the glioma group had an increased incidence of left and right brain inconsistencies during sedation and a decreased incidence of increased overall functional connectivity.

Conclusions: Patient State Index and EEG power spectrograms of glioma patients can reflect the depth of sedation of patients, but lack functional connectivity information. In the EEG functional connectivity analysis, the functional connectivity was reduced in the glioma group during sedation, and there was no such difference between the two groups during awake. The EEG functional connectivity relationships could be interpreted as different combinations of 7 temporal dynamic features microstates, with an increased incidence of left and right brain inconsistencies during sedation and a decreased incidence of increased overall functional connectivity in glioma group during sedation. The study suggests a possible new direction for the monitoring of potential neurological dysfunction in glioma patients.

[SNACC-45] Emergence Delirium: Should We Start Reconsidering our Approach to High-risk Patients?

Hallo-Carrasco A*, Hallo C, Gruenbaum B*, Gruenbaum S*. Mayo Clinic, Jacksonville, Florida, United States*. Icahn School of Medicine at Mount Sinai, Elmhurst Hospital, New York, New York, United States

Case description: A 22-year-old woman with a history of eosinophilic gastroenteritis, gastric ulcers, hypothyroidism, gastroesophageal reflux disease, irritable bowel syndrome, postural tachycardia, major depressive disorder, dissociative disorder, post-traumatic stress disorder, anxiety, and asthma developed delirium in the post-anesthesia care unit immediately upon emergence from an uneventful esophageal gastroduodenoscopy and colonoscopy. She received midazolam, lidocaine, a propofol infusion, and ondansetron during the procedure. The patient developed altered mental status in the PACU, including severe agitation and self-harmful behavior such as face and arm scratching. A bolus of haloperidol and dexmedetomidine was administered with no improvement in her delirium. She was restrained to prevent any further self-harm. She fully returned to her baseline level of consciousness one hour emergence from anesthesia. She had no recall of any events that occurred in her delirious state, and had no memory loss or disorientation. She was discharged to home in stable condition.

Discussion: Emergence delirium (ED) in the PACU is a multifactorial and potentially life-threatening condition that presents immediately upon emergence from anesthesia. In most cases, ED is self-limited but has been reported as a risk factor for postoperative delirium (POD) and subsequent long-term cognitive deficits. Due to the short-term nature of ED, early screening of delirium signs is not a standardized practice, which can result in a patient being discharged from the PACU with delirium-like signs. This raises the concern that the reported 5% incidence of ED might be a gross underestimation. Moreover, it has been reported that up to 19% of patients demonstrate some mild delirium-like symptoms within 10 minutes of emergence from anesthesia, and almost 4% of patients have persistent agitation after being discharged from the PACU.

Our patient presented with a clinical picture consistent with hyperactive delirium with agitation, with a risk of self-harm. Although hyperactive delirium is often easily identified and diagnosed, only 44% of patients with delirium present with agitation. By contrast, hypoactive delirium is often overlooked by providers. This more challenging presentation includes psychomotor retardation and lethargy, which is associated with poor outcomes and an increased risk of mortality. Importantly, delirium is rarely screened for and is typically diagnosed in the PACU only after demonstrating signs of delirium.

For these reasons, there is a clear need for a standardized early screening for preoperative hyperactive and hypoactive signs of delirium. Adequate preoperative anxiolysis is also critical in patients at high risk of ED. A loading dose of dexmedetomidine (0.4 mL/kg bolus) over 15 minutes immediately before induction of anesthesia, followed by a maintenance dexmedetomidine infusion (0.1 mL kg−hour) until one hour before the anticipated end of surgery has been shown to be useful in reducing the rate of ED and postoperative delirium in open transthoracic esophagectomies. The protective effect of this alfa –2 adrenergic receptor agonist could be related to a decrease in pro-inflammatory cytokines that correlate with ED and POD. Our objective is to raise interest in screening for ED in high-risk patients, and to promote consideration for adjuvants such as dexmedetomidine to prevent ED.

[SNACC-46] Emergent Warfarin Reversal for an Acute Subdural Hematoma Complicated by Left Ventricular Assist Device and a History of Heparin-Induced Thrombocytopenia

Pogu J, Chao S, Huang J. Mayo Clinic, Rochester, Minnesota, United States

We present a case of a 62-year-old male with a left ventricular assist device (LVAD) and a history of heparin-induced thrombocytopenia (HIT) who required emergent reversal of warfarin anticoagulation in the setting of an acute traumatic subdural hematoma (SDH) with progressive midline shift. To prevent neurologic decline in patients with intracranial hemorrhage (ICH), rapid reversal of anticoagulation is imperative. Reversal of vitamin K antagonists (VKA) was historically achieved with the administration of fresh frozen plasma (FFP) and vitamin K. This has shifted to the use of prothrombin complex concentrates (PCC), which include 4-factor PCC and activated PCC (aPCC), of which Factor Eight Inhibitor Bypassing Activity (FEIBA) is an example. Compared to FFP, PCCs normalize international normalized ratio (INR) more rapidly1 with a decreased risk of pathogen transmission, volume overload and transfusion-related acute lung injury. Previously, the concern for PCC-associated thromboembolic events limited widespread use, but recent studies demonstrate risk of thromboembolic events is equivalent to that following FFP administration2. After a fall from a recliner, our patient presented neurologically intact with a 4mm SDH and an INR of 4.4. Due to his LVAD and a history of HIT, he received one unit of FFP and 10 mg parenteral vitamin K. While awaiting transfer to a tertiary care center, he became encephalopathic with left hemiparesis. A repeat head CT demonstrated SDH expansion with 14mm midline shift and subfalcine herniation. Pending emergent surgical decompression, a multispecialty decision was made to administer FEIBA. 4F-PCC contains factors II, VII, IX, X, proteins C and S, as well as heparin to prevent factor activation. Our patient’s history of HIT precluded use of 4F-PCC. FEIBA contains activated clotting factors IIa, VIIa, IXa, Xa, proteins C and S without heparin3. Most data surrounding FEIBA’s use is in patients with hemophilia A or B, its only FDA indication. However, FEIBA has been used off-label for anticoagulant reversal.1 Yin et al demonstrated faster rates of INR reversal for those who received FEIBA versus FFP, with equivalent incidence of thromboembolic events and all-cause mortality2. There remains a paucity of data on the use of FEIBA in patients on LVAD support. Most existing studies have focused on the use of 4F-PCC for perioperative coagulopathy following LVAD implantation. Thromboembolic events are of particular concern in the LVAD population given the grave ramifications of pump thrombosis. In a retrospective study of FEIBA use for perioperative hemorrhage in LVAD implantation, O’Donnell et al found no associated increase in 14-day thromboembolic events, including pump thrombosis; and there was no difference in mortality3. Our patient received 500 units of FEIBA, with a subsequent INR of 1.1. His intraoperative course was uncomplicated with satisfactory, sustained hematoma evacuation and no apparent thromboembolic events. His subsequent hospital course was complicated by status epilepticus, severe bradycardia, and profound cardiogenic shock. Meaningful neurologic recovery was deemed unlikely, and he passed away soon after transition to comfort cares. Although the outcome of our patient’s clinical course was unfavorable, the use of FEIBA in this exceptionally challenging case allowed for rapid reversal of a supratherapeutic INR, enabling uncomplicated neurosurgical intervention, without evidence of pump thrombosis or another acute thromboembolic event. Much remains to be investigated prior to FEIBA’s widespread use for anticoagulation reversal. Large-scale studies focused on thromboembolic event incidence in FEIBA versus 4F-PCC and FFP are needed, as are studies examining the role of FEIBA dosing on its efficacy, incidence of thromboembolic events, and mortality.

[SNACC-47] Erector Spine Plane Block Improves Analgesia after Minimally Invasive Awake Spine Surgery

Colontonio M, Bojaxhi E, De Biase G, Abode-Iyamah K. Mayo Clinic, Jacksonville, Florida, United States

Introduction: Neurosurgical procedures are often performed under general anesthesia. However, there is an emerging interest in the neurosurgical clinical practice for lumbar spine surgery to be performed under spinal anesthesia (SA)1. The potential advantages of regional anesthesia include the lack of airway instrumentation, decreased opioid consumption, stable hemodynamics, a shorter hospital stay, and reduced health care costs1,4.

Our clinical practice has adopted SA for minimally invasive spine surgery as part of our enhanced recovery pathway which aims to facilitate early ambulation, decreased post-operative nausea vomiting (PONV), reduced pain, and decreased opioid consumption. Bilateral lumbar erector spinae plane (ESP) blocks are also described as a useful regional anesthetic technique to reduce post-operative pain after lumbar surgery3. The purpose of our study is to investigate the analgesic benefit of the ESP block to our awake lumbar spine neurosurgical patient with the goal of further facilitating recovery.

Methods: Institutional review board approval was obtained (IRB- 21-011367) to review the medical record of patients that underwent an awake lumbar spine surgery with or without a block. The medical record of patients that underwent spine surgery under SA before our practice adopted ESP blocks for back surgery, were considered as our historical control.

On day of surgery, patients underwent SA with 3 mL of 0.5% isobaric bupivacaine under conscious sedation. Anxiolysis during the surgery was maintained with a continuous infusion of intravenous dexmedetomidine at 0.2 mcg/kg/h. All patients were given prophylactic antiemetics and multimodal analgesics which included ondansetron, dexamethasone, acetaminophen, and celecoxib.

For the patients that received an ESP block, the injection was performed after skin closure above the level of the surgical intervention. Under ultrasound guidance, the erector spinae muscle layer was visualized and hydrodissected with normal saline away from the transverse process. Once appropriate needle position was confirmed, the block was performed with 15 mL of 0.5% bupivacaine mixed with 15 mL of liposomal bupivacaine (30 mL of local anesthetic per side).

A retrospective chart review was then performed analyzing time in OR, first pain score in PACU after spinal wore off, pain scores throughout POD 0, opioid requirements (converted to morphine milli-equivalents), PONV requiring rescue agent, and length of stay. Mean, median, T-tests and chi square were used to calculate power and differences between observed and expected values.

Results: There was no significant difference in age (50-80 yo), sex, ASA class (II-IV), and BMI (29.6 kg/m2). Perioperative opioid use on POD0 was more than double in those not receiving a block (P=0.0032). First pain score in recovery following conclusion of the spinal was greater than those who had received the intervention with a P-value of 0.0209. Median length of stay in days was the same with a larger range in the non-intervention group. Incidence of nausea/vomiting was decreased in the group receiving ESP blocks.

Discussion: An ESP block can be used as an adjunct for minimally invasive spine surgery for enhancing recovery. Preliminary data suggests there is a trend for lower incidence of PONV as well as average pain scores on POD0. However, as we are still in the early phase of data collection, these data points are currently underpowered. Regardless, it is evident that there is a significant decrease in perioperative opioid use, increased same-day discharges, and improved pain scores upon conclusion of SA. It is expected that with decreased use of opioids, there will be decreased nausea/vomiting and decreased length of stay following surgery. It is apparent that additional studies and more data needs to be collected regarding the effectiveness of ESP blocks for awake spine surgery, but early results are promising (Table 1).

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TABLE 1

[SNACC-48] Experience in Neuroanesthesia Practice from Indonesia Tertiary Hospital during COVID-19 Pandemic Era: A Descriptive Study

Firdaus R, Napitupulu L. Cipto Mangunkusumo Hospital, Jakarta, Indonesia

Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) or COVID-19 pandemic was a highly contagious virus that was first reported in the city of Wuhan, China in December 2019. COVID-19 pandemic has been a challenge to the global healthcare system and healthcare professionals including Indonesia. The first case found in Indonesia was in March 2020 and there were three peaks of the case, which were in January 2021, July 2021, and February 2022. Cipto Mangunkusumo Hospital, as a tertiary level and national referral hospital, was assigned as one of the biggest COVID-19 center hospitals in Indonesia. Throughout the pandemic, several policies regarding anesthesia practice were made, including the COVID-19 screening system and surgical patient pathway. Thus, there were two exclusive negative pressure operating rooms located in a centralized COVID-19 building and an emergency unit. Many surgical procedures were performed during the pandemic, including neurosurgical cases which involved neuro anesthesia practices that needed some adjustment due to the pandemic. There are two main questions that will be addressed in this research. First, Of all patients that undergo neurosurgery procedures how many have COVID-19. Second, Of all COVID-19 patients that undergo surgery how many of them are neurosurgery.

Methods: This study was descriptive and involved a retrospective review of data collected from patients who underwent neurosurgeries between March 2020 and March 2022. Analyzes were performed according to COVID-19 status, age, classification case, type of surgery, and type of anesthesia. Result: A total of 933 neurosurgery cases and 488 COVID-19 surgery cases were identified. There were 26 neurosurgery cases with COVID 19. It was about 2.7% relative to all neurosurgery cases and about 5.3% relative to all COVID 19 surgery cases. General anesthesia was conducted in all of the cases. Fifty percent of the surgery was performed in centralized COVID-19 building operating room with elective setting, following 46% of cases was performed in emergency unit. There was one case was performed in catheterization lab. The population of cases was 65.3% in adult patients and 34.7% in pediatric population, consisted of eight vascular cases, seven oncology cases, seven infection cases, three trauma cases, and one congenital case. The procedure performed were 57.6% cerebrospinal fluid diversion, 34.6% craniotomy and 7,6% debridement. We followed our hospital established local COVID-19 guideline for surgical procedures, international guidelines, and recommendations, such as SNACC, to help deciding the risk stratification and time to perform the procedures. However, we have not performed trans-nasal procedure, awake craniotomy, and intraoperative neuromonitoring. All safety measures and infection control protocols were implemented.

Conclusion: Neurosurgical procedures for patient with COVID-19 are considered uncommon with respect to all COVID-19 surgery cases and all neurosurgery cases. This information can be taken into consideration when making guidelines in the pandemic era. Further research are needed to explore impact of COVID-19 to neurosurgery patients.

[SNACC-49] Extracranial-Intracranial Revascularization in a Patient with Severe Pulmonary Hypertension

Rishel C, Shah S, Fielding-Singh V, Jaffe R. Stanford Health Care, Stanford, California, United States

Case description: A 59-year-old, 59 kg male with a medical history significant for idiopathic pulmonary fibrosis, severe WHO group 3 pulmonary hypertension (estimated RVSP 88 mmHg) and unilateral right-sided moyamoya disease presented for a craniotomy for extracranial-intracranial revascularization. In the months prior to surgery, the patient had developed an increasing home oxygen requirement and began experiencing episodes of syncope, typically in the setting of coughing episodes. During evaluation for possible bilateral lung transplant, it was discovered that he had unilateral right sided moyamoya disease. A multidisciplinary team determined that that he should undergo cerebral revascularization prior to transplant to reduce the risk of stroke.

The patient was preadmitted the day prior to surgery to ensure medical optimization. A PICC line, introducer sheath, and a continuous cardiac output catheter were placed, and a dopamine infusion at 2 mcg/kg/min was administered overnight. Upon arrival to the operating room, epinephrine 0.05 mcg/kg/min was initiated and a preinduction arterial line was placed. Transthoracic echocardiography was performed which showed significantly improved right ventricular function compared to his most recent outpatient echocardiogram. Transesophageal echocardiography and a defibrillator were available in the operating room, and cardiothoracic surgery was informed in case escalation to extracorporeal life support was necessary.

After preoxygenation, general anesthesia was induced using fentanyl 10 mcg/kg, two doses of propofol 0.25 mg/kg, and rocuronium 1 mg/kg. Mask ventilation was immediately initiated to prevent any increase in pulmonary vascular resistance due to hypercarbia or hypoxia. The patient became hypotensive shortly after induction which was promptly corrected using boluses of vasopressin 0.5 units and epinephrine 30 mcg, and a vasopressin infusion was initiated at 0.04 units/min. The patient was intubated uneventfully using video laryngoscopy and maintenance was achieved using sevoflurane 0.7%, propofol 25 mcg/kg/min, and remifentanil 0.1 mcg/kg/min. Inhaled nitric oxide 20 ppm was also initiated.

After intubation, the patient became increasingly hypotensive, and of particular concern, his systemic arterial pressures briefly reached within 15% of his pulmonary arterial pressures, requiring multiple larger boluses of vasopressin, epinephrine, and norepinephrine to correct. Hemodynamic stability was achieved using infusions of epinephrine 0.1 mcg/kg/min, norepinephrine 0.22 mcg/kg/min, and vasopressin 0.06 units/min to maintain a mean arterial pressure between 90-100. Adequate ventilation was challenging, requiring a minute ventilation of 12 L/min to maintain a PaCO2 in the mid-40s leading to relatively high peak pressures and some concern for auto-PEEP. Positioning and surgical exposure proceeded uneventfully. Immediately prior to temporary occlusion for revascularization, burst suppression was induced for neuroprotection using propofol 70 mg administered with norepinephrine 32 mcg (to preempt hypotension), and revascularization was completed in 21 minutes. Surgical closure was completed uneventfully. To evaluate the suitability for extubation given high ventilatory requirements, an intraoperative chest X-ray was obtained, which showed mildly worsened diffuse opacities, but no other acute pathology. Emergence was attempted but led to coughing and production of thick brown sputum through the endotracheal tube. The patient was re-anesthetized, bronchoscopy was performed to permit suction removal of moderate secretions, and the patient was transported intubated to the ICU. The patient was successfully extubated the following day and remained neurologically intact.

Discussion: Patients with moyamoya disease typically require induced hypertension prior to revascularization to maintain adequate cerebral perfusion. Pulmonary hypertension is a life-threatening condition that requires complex management in the perioperative period. Both conditions require strict avoidance of hypotension to ensure adequate cerebral and coronary perfusion pressures. Given the potential for rapid hemodynamic changes with complex etiologies and little tolerance for error, advanced monitoring and therapeutics are required to accurately manage preload, inotropic support, and afterload, and plans should be made regarding the possibility of escalation to extracorporeal support (Fig. 1 and 2).

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FIGURE 1:
Preoperative transthoracic echocardiogram. An apical 4 chamber view demonstrated right ventricular enlargement and septal flattening. Doppler of the tricuspid valve regurgitation jet corresponded to an estimated right ventricular systolic pressure of 88 mmHg.
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FIGURE 2:
Preoperative CT angiography demonstrated a proximal M1 occlusion with a tangle of collateral vessels in the right MCA territory.

[SNACC-50] Fetal Doppler as a substitute for precordial doppler in detecting venous air embolism during seated suboccipital craniotomy for vermian arteriovenous malformation excision

Tomanek A, Davenport O, Hoffmann U, McDonagh D, Welch B. University of Texas Southwestern Medical Center, Dallas, Texas, United States

Precordial Doppler is the standard of care for detection of venous air embolism (VAE) in sitting craniotomy. Many precordial Dopplers are aging and parts are difficult to replace, only exacerbated by product discontinuation by primary manufacturers. The need for an alternative device is imperative. Transesophageal echocardiography, considered the gold standard for VAE detection, is a readily available option, but the probe is difficult to use given the degree of head flexion, risk for oropharyngeal mucosal injury, and required operator expertise. Fetal Dopplers while traditionally used for routine monitoring of fetal heart tones could potentially fulfill the void left by precordial Dopplers. We postulated that a fetal Doppler could be used in place of the traditional precordial Doppler for VAE detection. There remain significant differences between the two devices regarding probe size, detection frequency, and creation purpose. However, a bubble test, in which one milliliter of air agitated with nine milliliters of normal saline injected into a central venous catheter, produced a distinct audible sound which assisted in probe placement and monitoring throughout the case. If a life-threatening VAE were to occur one could be reasonably confident in detecting it with a fetal heart Doppler.

[SNACC-51] Fixing Spines: First Steps Towards an Enhanced Recovery Programme for Lumbar Fusion Surgery

Lunardi D, Addy M. St Georges University Hospital NHS Foundation Trust, London, United Kingdom

Background: Enhanced Recovery After Surgery (ERAS) was first described in 1997 by Henrik Kehlet, as a multifaceted, multidisciplinary approach to improve patient outcomes in colorectal surgery. Subsequently, the ERAS society has endorsed similar protocols across a variety of surgical specialties. The society published a consensus statement suggesting items for inclusion in a lumbar fusion surgery enhanced recovery protocol in 2021.

The purpose of this audit was to capture our current peri-operative practice for lumbar spine fusion surgery for degenerative disease relative to these suggestions, and identify changes required to build an enhanced recovery protocol.

Methods: A total of 55 patients were listed for lumbar fusion surgery via our surgical booking programme, from March 2021 until February 2022. After excluding duplicate, paediatric, traumatic and malignant cases, electronic patient records of 30 patients were analysed, recording adherence to the consensus statement.

Pre-operative parameters analysed were: pre-operative counselling, with the provision of written, procedure specific information; referral to alcohol liaison services (if consumption exceeded recommended limits); appropriate referral of patients to smoking cessation services; identification and referral of patients with pre-operative anaemia ( Hb <130 g/L); a completed Malnutrition Universal Screening Tool (MUST). Intra-operative parameters analysed were: pre-operative fasting times; administration of pre-anaesthetic analgesia; use of intrathecal, epidural or regional anaesthetic techniques; routine use of prophylactic antibiotics and skin prep; use of a standard anaesthetic protocol; prevention of hypothermia; euvolaemic fluid management. Post-operative parameters analysed were: multimodal analgesia; routine use of multimodal antiemetics; early post operative nutrition; early mobilisation; routine thromboprophylaxis; use of wound drains; incidence and duration of urinary catheterisation.

Results: see Results Fig. 1 and Results Fig. 2.

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FIGURE 1:
Results.
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FIGURE 2:
Results.

Conclusion: Our results show that significant improvement is required to meet recommended preoperative criteria, particularly the identification of anaemia, and nutritional screening. However, we have demonstrated some areas with good adherence to ERAS criteria including early post-operative nutrition, multimodal analgesia, multimodal antiemetics, skin prep and antibiotic prophylaxis, and thromboprophylaxis.

A major limitation of this audit is that we were unable to analyse many intra-operative parameters due variability in completion and storage of peri-operative documentation.

In response to our findings we plan to deliver an educational programme in the pre-assessment clinic and to introduce a departmental ERAS protocol. To improve data collection we will incorporate a single “ERAS document” within patient notes. This should allow continuous monitoring of all criteria with targeted intervention to help achieve departmentally agreed adherence targets and to correlate adherence to ERAS guidelines against surgical outcomes.

[SNACC-52] General Anesthesia vs Monitored Anesthesia Care During Mechanical Thrombectomy For Acute Stroke Treatment

Fallahian W, Amlong C, Krause B. University of Wisconsin, Madison, Wisconsin, United States

Ischemic stroke accounts for nearly 1 in 19 deaths in the United States, ranking it fifth among all causes of death. Methods of acute stroke treatment are continuously evolving, with endovascular thrombectomy considered the gold standard. However, the anesthetic management of patients undergoing thrombectomy remains controversial. Multiple studies have shown that monitored anesthesia care (MAC) or procedural sedation leads to better outcomes compared to general anesthesia (GA) (1,2), while others have shown no difference (3). Here we present data comparing GA vs MAC obtained from a retrospective review of patients presenting with ischemic stroke who underwent mechanical thrombectomy. Our primary endpoint was functional outcome as measured by Modified Rankin Score (MRS) at 90 days. Our secondary endpoints included in-hospital death, death at 90 days, time to procedure start, time to recanalization, total procedure duration, successful revascularization, ICU length of stay and total hospital length of stay. After approval of an IRB exemption request, charts of consecutive patients presenting to the University of Wisconsin with ischemic stroke who underwent mechanical thrombectomy between January 2018 and December 2020 were reviewed. Ultimately 368 patients were included in the analysis. Patients who were converted to GA after an initial attempt at MAC were considered in an intent-to-treat manner as MAC patients. Patients in each group were similar in terms of age and gender, however, NIHSS were higher in the GA group compared to the MAC group (14.4 vs 11.2, P=0.00027). In general, procedure times in the MAC group were shorter compared to the GA group: door to skin puncture time (5.2 min shorter), door to reperfusion time (21% shorter), and total procedural time (20% shorter). ICU stays were shorter for patients who underwent MAC (30% shorter) as were total hospital stay times (22% shorter). Modified Rankin Scores were not significantly different between the two groups (odds ratio MAC vs. GA=0.82). In-hospital deaths were not significantly different between the two groups (odds ratio MAC vs. GA=0.48). Overall TICI scores were similar between the two groups (odds ratio=1.0), however, the incidence of “successful” reperfusion (as defined as a TICI score of 2b or higher) was higher in the GA group (odds ratio MAC vs. GA=0.38). Pre-procedure NIHSS and age were found to be predictors of in-hospital death, but anesthesia type during endovascular stroke treatment was not. The type of anesthesia used at our institution for a mechanical thrombectomy is determined after discussion between the anesthesia team and the proceduralist. We found that the baseline characteristics of age and gender were similar between the GA and MAC groups, however, NIHSS was greater in patients receiving GA. This is most likely since patients with a more severe stroke may have difficulty holding still during the procedure and are selected to undergo GA. After accounting for baseline characteristics of age, gender and NIHSS, we found that there was no significant difference in our primary endpoint of Modified Rankin Score at 90 days. With regards to our secondary endpoints, we also found there was no significant difference in in-hospital death, or death at 90 days. We found that MAC cases were faster to get underway, had a shorter time to recanalization as well as a shorter total procedure time. This is contrary to other studies showing that completely still patients under GA lead to faster reperfusion. ICU and hospital stay were also found to be shorter in the MAC group. With regards to successful reperfusion (TICI 2b or higher), we found this was higher in the GA group. Given a lack of significant difference in long-term outcomes, we conclude that both anesthesia strategies are viable options.

[SNACC-53] Hearts and Minds: Awake Craniotomy with a Reduced Ejection Fraction

Stowe J, Huang J. Mayo Clinic, Rochester, Minnesota, United States

We present the case of a 53-year-old male with new-onset seizures and presumed left temporal glioma who presented for awake craniotomy for tumor resection. His medical history was notable for idiopathic dilated cardiomyopathy with a left ventricular ejection fraction of 31%. Perioperative cardiac concerns were discussed with the surgeon who indicated that an awake approach was mandatory during tumor resection due to the close proximity of language activation centers to the lesion (Fig. 1). He was evaluated by Cardiology preoperatively, and he denied symptoms of heart failure and reported being able to achieve > 4 METs. In preparation for close hemodynamic monitoring and possible need for inotropic support, a radial arterial line and femoral central line were placed under sedation with dexmedetomidine infusion and remimazolam boluses. Due to his baseline cardiac function, an arterial pulse contour system (Flo-Trac™) was utilized for real-time assessment of cardiac output intraoperatively. Infusions of norepinephrine and epinephrine along with a syringe of double dilute epinephrine were immediately available in case of need for inotropic or vasopressor support. His baseline cardiac index was 2.6 L/min/m2. After line placement, sedation was deepened with the addition of propofol and remifentanil for lateral decubitus positioning, pinion placement, surgical incision, and initial exposure. Local anesthetic was infiltrated by the surgical team. After the dura was opened, all sedation was turned off allowing return to a completely awake state. Continuous cognitive and language testing was performed by Neuropsychology during tumor resection. The patient tolerated the procedure well and ultimately did not require any vasopressor support. During the awake portion, his blood pressure gradually rose to systolics above 160 mmHg and cardiac index trended down to 1.8 L/min/m2. At this point, a clevidipine infusion was started to optimize afterload and cardiac function with improvement in cardiac index back to baseline. Remifentanil infusion was restarted prior to closure. The patient tolerated the remainder of the procedure well and was transferred to the recovery room without incident. This case highlighted several important considerations in the management of an awake craniotomy in a medically complex patient. Appropriate preparation for airway, access, and monitoring is always prudent. In this patient with a reduced ejection fraction, central venous access and real-time cardiac output monitoring were utilized in case of need for inotropic support. Sedation medications were carefully chosen for rapid onset and offset given the importance of maintaining stable hemodynamics as well as offering expedient return to wakefulness intraoperatively. Management of possible intraoperative events such as choice of abortive medications in case of seizure was also considered preemptively. Thorough preparation and open communication with the surgical team was paramount in achieving an optimal outcome for this medically complex patient.

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FIGURE 1:
T2-weighted axial MR image demonstrating minimally enhancing posterior left temporal lobe lesion.

[SNACC-54] Hemodynamic Support for 5-Aminolevulinic Acid (ALA) Associated Hypotension during Craniotomy for Tumor Resection

Kisilevsky A*, Lee C, Barreto Chang O, Berger M, Hervey-Jumper S, Whitlock E. University of British Columbia, Vancouver, British Columbia, Canada*. University of California San Francisco, San Francisco, California, United States

Background: 5-aminolevulinic acid (ALA) may facilitate greater extent of resection and improve survival in patients with glioma. Low blood pressure has been reported as a potential adverse effect of ALA but little is known about perioperative incidence, risk factors, or associated postoperative outcomes in neurosurgery. Intraoperative hypotension has been associated with adverse outcomes. Our aims were: 1. To investigate the incidence and severity of hypotension in patients who receive ALA for craniotomy; 2. To explore possible patient and anesthetic risk factors and postoperative outcomes in patients who experience ALA associated hypotension during neurosurgery.

Methods: All adult patients who underwent elective craniotomy for glioma resection with ALA fluorescence-guided assistance between July 2012 and October 2018 were retrospectively identified. Cases were matched 1:1 to control patients (no ALA) who underwent craniotomy for tumor resection and received the same anesthetic strategy (general anesthesia [GA] versus monitored anesthesia care [MAC]) during the same time period. Patient demographic, anesthetic, procedural, and postoperative outcome data were collected including perioperative blood pressure and the need for vasopressor administration. The primary outcome was defined as the use of any of the following vasopressors for the treatment of hypotension: high dose phenylephrine infusion at 50 mcg/min or greater, ephedrine, epinephrine, norepinephrine or vasopressin. Multivariable logistic regression was applied for the primary analysis. The remaining data were analyzed using Fisher’s exact test between the two groups.

Results: 268 patients who underwent craniotomy for brain tumor resection including 134 patients who received ALA and 134 matched controls were identified. After adjusting for age, ASA physical status, home use of antihypertensive medication, and anesthetic strategy (MAC or GA), ALA use was associated with an odds ratio of 3.07 (95% CI: 1.69–5.59, P<0.0001) for vasopressor use. The association between ALA and vasopressor use held in post-hoc sensitivity analysis including stratification by anesthetic type (MAC or GA) and ASA physical status dichotomized as 1-2 or 3+, and an ordered logistic model taking into account the number of pressors used. In further exploration of the severity of hypotension needing vasopressor support, the incidence of treatment using either one vasopressor or two or more vasopressors was significantly higher in the ALA group (P=0.002) (Fig. 1). Seven patients remained on vasopressor support postoperatively in the ALA group compared to none in the control group. There was no difference in extended ICU length of stay, the incidence of ischemic stroke, cardiac dysfunction, or renal insufficiency after surgery between the two groups.

F27
FIGURE 1:
Comparison of the number of vasopressors used to support blood pressure during craniotomy for tumor resection between ALA and control groups. The use of either one vasopressor (1) or two or more vasopressors (2+) was significantly higher in the ALA group compared with control (P=0.002) using Fisher’s exact test.

Conclusion: Patients who receive ALA for brain tumor resection are at three-fold increased odds of intraoperative hypotension requiring high dose vasopressor management. Blood pressure support after surgery may be needed in patients who receive ALA. Physicians who care for this patient population should be vigilant and prepared to manage this potential perioperative morbidity to reduce the risk of adverse outcomes. Further prospective studies are needed to assess risk.

[SNACC-55] How reliable is the Surgical Outcome Risk Tool (SORT) at predicting postoperative 30-day mortality after neurosurgery?

Hussein Z, Luoma V, Douglas D, D’Antona L, Toma A. National Hospital for Neurology and Neurosurgery, UCLH NHS Foundation Trust, London, United Kingdom

Background: Risk stratification tools are an important component of perioperative planning, patient preparation, shared decision-making and resource allocation. The Surgical Outcome Risk Tool (SORT) is a validated, simple, risk prediction tool used to estimate risk of death within 30-days of surgery in the adult surgical population 1. The aim of this study was to determine if SORT can reliably predict 30-day postoperative mortality following elective and expedited cranial neurosurgery.

Method: This was a retrospective study conducted at a tertiary-level single-specialty neurosurgical centre. All adult patients (>18 y) undergoing elective and expedited cranial neurosurgery between May - August 2019 were included. Data collected included patient demographics, ASA-grade, Rockwood Clinical Frailty Scale (CFS), type of surgery, length of post-operative stay (LOS) and 30-day post-operative mortality. We used the validated online National Confidential Enquiry into Patient Outcome (NCEPOD) SORT2 risk assessment tool to calculate SORT score. Using SPSS statistical tool, descriptive analysis was done to determined mean with standard deviation for all variables and Pearson correlation was used to evaluate relationship between SORT score and actual 30 day mortality. A P-value <0.05 was considered significant.

Results: 243 patients were included; 180 (74%) underwent elective cranial surgery, and 63 (26%) had expedited surgery. 57% were female with mean (sd) age 53 (±14.2) years, BMI 26.7 (±5.4) and median ASA 2 (1 -4,±0.67) and CFS 3 (2–7, ±0.84). 67% patients had ward-level post-operative care. The mean length of stay was 7 (SD±8) days. The overall 30-day mortality was 2.88% (n=7). The mean SORT mortality risk score for our entire patient cohort was 0.512 (SD±0.99), with predicted 30 day mortality of 1.24%. Subgroup analysis showed patients undergoing elective cranial neurosurgery had a lower predicted 30-day mortality (Mean SORT score 0.254 SD±0.30), compared to patients undergoing expedited surgery (mean SORT score 1.251 (SD±1.69) (Table 1). Using Persons correlation coefficient model, we determined that SORT risk assessment tool is accurate at predicting 30-day postoperative mortality (P<0.001).

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TABLE 1

Conclusions: Our results are in-keeping with published data and suggest that SORT can reliably be used to predict postoperative 30-day mortality following cranial neurosurgery in our patient cohort1. However, in higher-risk patients SORT may overestimate mortality and might therefore not be reliable in this population group. Previous studies in colorectal surgery demonstrate similar results. The new SORTv2 risk tool which combines SORT with clinical judgement may predict risk and 30-day postoperative mortality more accurately in this vulnerable neurosurgical population. Further studies are required to investigate this. Limitations of this study include a single centre, retrospective study. Only a small number of patients were high-risk limiting analysis.

[SNACC-56] ΡΚΜζ Mediating Neuroprotection By Sevoflurane Preconditioning Is Differentially Phosphorylated from ΡΚΜζ Required For LTP/LTM Maintenance: Implications For Post-Operative Cognitive Dysfunction

Tsokas P, Rodriguez Valencia L, Desai M, Kass I, Sacktor T, Cottrell J. SUNY Downstate Health Sciences University, Rockaway Park, New York, United States

PKMζ is a brain-specific, autonomously active atypical Protein Kinase C isoform, essential for the formation and maintenance of LTP and long-term memory (LTM). In addition to being a memory molecule, PKMζ also serves a neuroprotective role: sevoflurane (sevo) preconditioning causes new PKMζ synthesis in hippocampal CA1, which mitigates the aversive effects of hypoxia on neuronal health (Wang et al, 2012). Previous findings from our lab have suggested that there may be compartmentalization of neuronal PKMζ into distinct pools, allowing sevo-induced PKMζ to exerts its beneficial effects without affecting pre-existing synaptic PKMζ involved in LTP/LTM. Here we show that the sevo-induced PKMζ is differentially phosphorylated from PKMζ synthesized in response to LTP and LTM: in contrast to LTP/LTM-associated PKMζ, which is phosphorylated on both T560 and T410, sevoflurane-induced PKMζ is not phosphorylated on T410. We propose that this differential phosphorylation designates PKMζ into functionally distinct intracellular compartments, i.e., an LTP/LTM-maintaining pool and a sevo-induced pool. Thus, sevo-induced PKMζ is excluded from synapses because it is not phosphorylated at T410, and therefore plays a role specifically in neuroprotection without effecting synaptic output. This compartmentalization mechanism allows the neuron to distinguish PKMζ involved in memory encoding from PKMζ synthesized by sevoflurane and involved in neuroprotection.

Methods: Acute hippocampal slices were prepared from adult male rats, and allowed to recover in an Oslo-type interface brain slice chamber. 4% sevoflurane (in 95% O2 and 5%) was delivered for 20 min. Slices without anesthetic delivery served as controls. All tissue was harvested by snap-freezing at 30 min after sevo washout. The CA1 regions were microdissected and lysed, and PAGE was performed on the lysates. The immunoblots were probed with antibodies against phosphorylated and total PKMζ, with actin serving as control.

Results: Immunoblots showed that 20 min sevo administration increased the expression of total PKMζ protein in CA1 (144±15% n=16 for sevo vs. 100±12% n=13 for control; P=0.03, t27=2.26) as previously reported (Wang et al, 2012), without significantly increasing pT410-PKMζ above basal levels (114±7% n=16 for sevo vs. 100±5% n=13 for control; P=0.14, t27=1.5). This finding contrasts to what has been described for LTP, where both total PKMζ and pT410-PKMζ are persistently increased in parallel (Kelly et al, 2007). Moreover, in agreement with Wang et al, (2012), sevo treatment increased the levels of PKMζ phosphorylated at T560 (145±16% n=8 for sevo vs. 100±12% n=8 for control; P=0.04, t14=2.24), which is similar to what has been observed for LTP (Kelly et al, 2007). Sevo-induced, newly synthesized PKMζ is therefore differentially phosphorylated at T410, but similarly autophosphorylated at T560, as compared to LTP/LTM PKMζ. This finding suggests that the phosphorylation state at T410 specifically determines the activation state and/or subcellular targeting of the kinase.

Conclusion: We find that sevoflurane preconditioning increases the expression of total PKMζ protein levels, without affecting its phosphorylation state at T410. Thus, PKMζ phosphorylation may constitute the basis of a mechanism that allows the neuron to distinguish PKMζ involved in memory encoding (and is phosphorylated in T410) from PKMζ involved in neuroprotection by sevo (which is not phosphorylated at that site). Under physiological conditions this compartmentalization of PKMζ preserves the integrity of pre-existing memory traces in the hippocampus. We hypothesize that when this compartmentalization breaks down — due to pathological conditions, spontaneous ripple activity in the anesthetized brain, or during emergence from anesthesia — the ensuing corruption of pre-existing engrams contributes to Post-Operative Cognitive Dysfunction.

[SNACC-57] Impact of age on the occurrence of processed EEG burst suppression

Kreuzer M, Kratzer S, Schneider D, Schwerin S. Technical University of Munich, München, Germany

Introduction: Over 200 million patients worldwide need surgical intervention with general anesthesia every year. Because of the aging society the number of geriatric patients will also increase which could lead to an increase in postoperative neurocognitive disorder, because age itself presents an independent risk factor. During general anesthesia, burst suppression (BSupp) patterns in the electroencephalogram (EEG) may also be associated with a negative cognitive outcome. EEG-based anesthesia monitoring systems provide the user with processed indices reflecting the anesthetic level as depth of anesthesia index and the occurrence of BSupp as “suppression ratio” (BSR). With our study we wanted to investigate the occurrence of intraoperative EEG burst suppression and related features and their relationship with age, based on processed EEG information and a large patient cohort.

Methods: From 88,997 electronic records of the perioperative period containing the processed EEG trend data, we included 54,266 patients with more than 90% valid trend data. The processed trends of the state entropy (SE) and SR were derived from the Entropy Module (GE Healthcare) with a resolution of one trend value each 10 seconds. Based on the trend data we investigated the change in (i) proportion of patients with detected BSupp, i.e., a BSR>0 with age, (ii) mean and maximum BSR with age, (iii) the change in relative BSupp duration with age, and (iv) in the proportion of intraoperative SE>80 indicating an “awake” patient which may be caused by misclassified suppression episodes with age. We further investigated the minimum MAC during anesthesia maintenance, a BSR>0 was observed with age. For statistical analysis we estimated linear models or created a polynomial fit of order 2.

Results: The proportion of patients with BSR>0 linearly increased with age: P(BSupp)=0.07*age+0.25 (rho=0.96 [0.94 0.99]; P<0.001) as presented in Fig. 1A. To for the maximum and median SR of patients with SR, we applied a polynomial fit with factor 2: max(BSR)=0.01*age2-0.54*age+65.24 (R2=0.28) and mean(BSR)=0.01*age2-0.66*age+38.39 (R2=0.63) (Fig. 1B-C). The duration of BSupp, relative to the anesthesia duration significantly increased with age: relBSuppDuration=0.002*age+0.014 (R2=0.12, P=0.002; Fig. 1D). The number of implausibly high SE also significantly increased with age P(highSE)=0.001*age+0.001 (rho=0.65 [0.48 0.83], P<0.001) as depicted in Fig. 1E. We also found that the minimal MAC during anesthesia maintenance a SR>0 was observed significantly decreased with age: minMAC=−0.003*age+0.801 (R2=0.25; P<0.001) as displayed in Fig. 1F.

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FIGURE 1:
Development of processed EEG parameters with age. A) The probability of burst suppression increases with age. B) The maximum BSR detected in the patient shows a biphasic course. C) The mean BSR detected in the patient shows a biphasic course. D) The BSupp duration relative to anesthesia duration increases with age. E) The occurrence of high SE>80 under anesthesia increases with age. F) The MAC burst suppression occurs decreases with age.

Conclusion: Our results highlight the strong dependence of the occurrence of (processed) BSupp on age. Further, BSupp occurs at lower age-adjusted MAC values with age. At the same time the proportion of misclassified BSupp also increases with age. Hence, older patients may me at risk of excessive levels of anesthesia reflected by BSupp which may contribute to the increased risk of postoperative neurocognitive disorders besides other independent factors.

[SNACC-58] Implementation of Civility Saves Lives in the Neurosurgical Theatre Department

Rehill R, Luoma V, Bapat S, Misra R. National Hospital for Neurology and Neurosurgery, UCLH NHS Foundation Trust, London, United Kingdom

Introduction: Incivility is defined as rude behaviour or rude remarks[1]. It comes from the Latin incivilis meaning ‘not of a citizen’ and includes belittling, sarcastic comments, ignoring, rebuking and embarrassing colleagues as well as non-verbal behaviours such as eye rolling. External stressors combined with a permissive environment allow this behaviour to occur. Stressors are personal and work-related stress, feeling rushed, over-worked, having low morale or suffering exhaustion[2]. Many of these are commonplace within the healthcare system, particularly during the last two years with the COVID-19 pandemic. Healthcare workplace incivility is common, reported up to 97% in the operating room[2] with a resultant impact on staff and presenting a patient safety risk. Katz et al[3] described significant differences in performance of anaesthetic trainees exposed to a polite or rude surgeon during a simulated intra-operative haemorrhage (91.2% vs. 63.6% (P=0.007) performing at expected level). 25% of staff who experienced incivility take this out on service users. 75% of service users who witness it are less enthusiastic about the organisation[4]. Reducing workplace incivility is part of the NHS Long-term Plan[5] and NHS People Plan[6]. Our primary objective was to determine prevalence of perceived disruptive behaviours within the operating room at a single-specialty neurosciences centre. Secondary objectives were to identify the most frequent types of disruptive behaviours and implement changes to reduce incivility.

Methodology: This survey is locally registered (ref: 10-202122-SE). An anonymous, electronic survey, using Google Forms, was disseminated to healthcare staff working in the neurosurgical operating rooms over 1-month (July 2021) using email cascades and established staff WhatsApp groups. Reminders were sent at week 2 and 3. The survey was previously validated[2] and consisted of two sections: exposure (14-items in 4 categories: personal; in-group; out-group; undirected and directed at patients) and responses (14-items) to disruptive behaviours. Data collected included staff demographics. Data was analysed using Microsoft Excel.

Results: The survey response rate was 49% (n=92; Table 1). 85% of responders perceived experiencing or witnessing disruptive behaviour, most frequently undirected (85%), and mostly a few times a year (personal 70%; patient-directed 67%; in-group 65%; out-group 68%; undirected 56%). A few respondents personally experienced disruptive behaviours on a monthly (4%), weekly (1%) or daily basis (1%). ‘Having work obstructed’ was the most frequently perceived personal (62%) or out-group (62%) disruptive behaviour, ‘sarcasm’ most common in-group (63%) and ‘speaking ill of others’ (85%) most common undirected behaviour. Response to perceived disruptive behaviours was assertive (68%), rarely malicious or manipulative (<1%). 47% accepted the behaviours as a part of normal operating room culture. Further subgroup analysis was not conducted due to small numbers. In response to our survey, we have taken the following actions:

  • Raising awareness: We have presented the results at multidisciplinary staff forums; including Hospital, Neuroanaesthetic and Neurosurgical Department Safety Forums and Operating Department teaching sessions.
  • Further education and awareness: Posters and infographics are displayed from the Civility Saves Lives movement[7], AAGBI #knockitout[8] and of survey results.
  • Staff encouraged to attend further training: Active Bystander, to develop tools to manage disruptive behaviours.

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TABLE 1:
Responder Demographics

Conclusion: Perceived disruptive behaviours may be common within the neurosurgical operating room environment. Our results are in keeping with published literature[2] and highlight an important patient safety risk. Encouraging staff to overcome incivility can improve team performance and reduce errors[3], creating a more supportive working environment, safeguarding patients and improving experience. Staff may be empowered to speak up when they see something that potentially jeopardises patient safety. We plan to resurvey once changes have been fully implemented for a period of 6 months to see whether greater awareness and empowerment of staff has made a difference.

[SNACC-59] Incidence of cardiac dysfunction after adult traumatic brain injury: A systematic review and meta-analysis

Chaikittisilpa N*, Kiatchai T*, Lele A, Vavilala M, Krishnamoorthy V. Siriraj Hospital, Mahidol University, Bangkok, Thailand*. University of Washington, Seattle, Washington, United States. Duke University, Durham, North Carolina, United States

Objectives: Cardiac dysfunction following traumatic brain injury (TBI) has been reported in observational studies, and may contribute to early hemodynamic instability. However, a robust estimate of the incidence of cardiac dysfunction following TBI is limited. We aimed to use systematic review and meta-analytic methods to estimate the pooled incidence of cardiac dysfunction among adult patients with TBI.

Methods: We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses standards (PRISMA) 2020 statement throughout this review. Literature search was conducted using MEDLINE and EMBASE databases, without language restrictions, from inception to June 2021. Observational studies were included if they reported at least one of the indicators for cardiac injury; (1) abnormal ECG findings (arrhythmias, QT prolongation, ST-T changes), (2) elevated cardiac troponin level, and (3) echocardiographic evaluation of systolic function or left ventricular wall motions in adult patients with TBI. We excluded studies published only in abstract form, case report, editorials, opinion articles and letters. Two investigators independently reviewed the studies, extracted the data and assessed the methodological quality of the individual studies using the Newcastle-Ottawa Scale (NOS). Cardiac dysfunction was defined as 1) elevated cardiac troponin level, low left ventricular ejection fraction (LVEF) or 3) presence of regional wall motion abnormality from echocardiography. The meta-analysis of pooled incidence of cardiac dysfunction was performed using random-effect model.

Results: The search returned 15,357 records and 123 studies were screened for inclusion and exclusion. A total of 51 studies in full text were accessed. Finally, 18 studies (3,699 participants) reporting cardiac function evaluation using either elevated cardiac troponin level or echocardiography in patients with TBI were included into meta-analysis. Most of the studies included patients with moderate-severe TBI. Presence of associated injuries, parameter used, timing of cardiac function evaluation and follow up varied between studies. Only two studies were considered fair quality, which included non-TBI controls. Most of the studies were considered poor quality due to lack of the non-TBI control group. The pooled incidence of cardiac dysfunction following moderate-severe TBI was 37.7% (95% confidence interval [CI] 35.7% - 39.7%; I2=12.5%). Fifteen studies (3,570 participants) reported elevated troponin level after TBI, among whom 38.2% (95% CI 36.2% - 40.2%, I2=12.3%) had cardiac dysfunction. Eight studies (423 participants) reported abnormal echocardiography, the pooled incidence of low LVEF or regional wall motion abnormality was 19.6% (95% CI 15.4% – 23.8%, I2=10.1%).

Conclusion: Although there are significant variations in patient selection, methods and timing of cardiac evaluation between studies, the findings suggest that cardiac dysfunction may occur in about one-third of the adult patients following moderate-severe TBI (Fig. 1).

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FIGURE 1:
Forest plot presenting pooled incidence of cardiac dysfunction following moderate-severe traumatic brain injury of the included studies.

[SNACC-60] International survey on extubation practices after infratentorial craniotomy

Goettel N*, Levy C, Jakus L, Meling T, Quintard H, Gaudet J§. University of Florida College of Medicine, Gainesville, Florida, United States and University of Basel, Basel, Switzerland*. Riviera-Chablais Hospital, Rennaz, Switzerland. Geneva University Hospitals, Geneva, Switzerland. Lausanne University Hospital, Lausanne, Switzerland§

Background: Delayed extubation after infratentorial craniotomy is associated with increased morbidity and mortality. The aim of the Predicting Infratentorial Craniotomy Extubation (PRICE) survey was to describe the practice patterns for extubation after elective infratentorial craniotomy among neuroanesthesiologists, neurosurgeons, and neurocritical care specialists.

Methods: Following research ethics board approval, the 15-question online PRICE survey was circulated to the members of five international medical societies over a 15-week period.

Results: Out of 505 individuals who connected to the survey website, 190 (37.6%) started the survey, with a 100% completion rate. Respondents represented a total of 99 institutions from 92 cities, in 27 countries. 134 respondents (70.9%) reported working in institutions with ≥ 30 cases per year. 63 respondents (34%) reported extubating less than 75% of cases in the operating room, at the end of surgery. The reported rate of early extubation was significantly associated with the reported hospital yearly caseload (P=0.029). The course of surgery (65.7%), preoperative bulbar dysfunction (64.7%), and preoperative altered consciousness (56.8%), were the three predictors most frequently selected by respondents to affect their decision to extubation strategy. The majority of respondents agreed that the risk of delayed extubation should always be discussed with patients prior to surgery.

Conclusions: There is wide variation of the reported rate of early extubation after elective infratentorial craniotomy. Respondents from high-volume institutions report different practice patterns. The course of surgery, evidence of bulbar dysfunction, and altered consciousness, appear to affect the decision to extubate early more than other predictors.

[SNACC-61] Intraoperative Blood Sugar Changes: A Randomised Control Study Comparing Sevoflurane and Desflurane

Dube S*, Kaushal A, Bindra A*, Chaturvedi A*. AIIMS, New Delhi, India*. AIIMS, Bhopal, India

Background: Anaesthetic agents can alter the neuroendocrine response to surgical stress which may affect blood glucose levels. [1-3] We aimed at comparing the effect of sevoflurane and desflurane on intraoperative blood glucose levels in patients undergoing intracranial surgery.

Methods: Seventy non diabetic adult patients undergoing elective intracranial surgery were randomized to receive either sevoflurane or desflurane as maintenance anaesthetic agent. Demographic and intraoperative variables were recorded. Hourly blood glucose levels were measured after induction until completion of surgery.

Results: The two groups were comparable in terms of demographic variables, type of intracranial pathology, intraoperative fluid volume as well as hospital and ICU stay. In the sevoflurane group, the mean blood glucose (mg/dL) significantly increased (P=<0.001) from a baseline value of 93.34±9.33 to a maximum of 102±8.61 at the 9 hours’ time point. However, in the Desflurane group, the mean blood sugar (mg/dL) increased from 89.34±9.85 at the baseline to a maximum of 92.37±9.92 at the 4 hours timepoint and then decreased to 88.50±0.71 at the 9 hours timepoint.

Conclusions: Sevoflurane caused a gradual increase in intraoperative blood sugar whereas an initial rise followed by a decline in blood sugar level was seen with Desflurane use in non-diabetic adult patients undergoing elective neurosurgery. These changes were statistically significant but remained clinically insignificant.

[SNACC-62] Intraoperative cerebral autoregulation monitoring in patients undergoing vascular neurosurgery

Pujol G*, Valero R*, Sterk J, de Riva N*. Hospital Clínic de Barcelona. Universitat de Barcelona, Bardelona, Spain*. Univeristeit Leiden, Leiden, Netherlands

Introduction: A certain amount of hypotension may be unavoidable during vascular neurosurgery procedures, increasing the risk of ischemia. It remains unclear whether cerebral autoregulation (CA) is still preserved intraoperatively. The continuous determination of intraoperative CA in this study is based on ICM+ software calculations using the cerebral oximetry index (COx).

Methods: Adults undergoing vascular neurosurgery (arteriovenous malformations (AVM) and aneurysms) were enrolled between October 2016 and February 2022 at the Hospital Clinic de Barcelona. To construct the COx, autoregulation was calculated using a moving Pearson’s correlation coefficient between processed near-infrared spectroscopy signals and arterial blood pressure (ABP). Impaired autoregulation was defined as COx> 0.3. The ABP where autoregulation is optimal (ABPOPT) was determined, as well as other autoregulation-derived variables. The relationship between patients’ outcomes and the studied variables was explored.

Results: 33 patients were included in the analysis (mean age 54±11 y). 85% patients had a mean Cox index <0.3 during the procedure. However, COx values were not uniform during the whole procedure, showing periods with preserved and non-preserved CA. Eighteen patients (55%) were autoregulated more than 70% of the time. AVM showed a significantly higher rate of disturbed autoregulation than aneurysms (40% vs 4,3% P=0.02). Mean ABPopt was 76.3±11.4 mmHg, with a range from 51.4 to 93.2 mmHg. Patients spent 64% of the monitored time with a ABP above or below ABPOPT (+/−5 mmHg). Good concordance was seen between mean values of ABP and calculated ABPOPT (0.69). Worse postoperative outcomes (mRS 3-6) were more frequently seen with a poor preoperative clinical condition. No differences in outcome were found related to autoregulation-derived parameters.

Conclusions: Most of neurovascular patients, CA is preserved intraoperatively. Further research containing a more extensive sample is required for performing multivariate analysis and investigating the potential clinical effect of sustaining CA intraoperatively (Fig. 1 and 2).

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FIGURE 1:
Distribution percentages of the recorded time where COx> 0.3.
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FIGURE 2:
Percentage of time where patients had ABPREAL 5 mmHg above or below ABPOPT (ABP delta).

[SNACC-63] Intra-Operative Goal Directed vs. Conventional Fluid Therapy in Aneurysmal Sub Arachnoid Hemorrhage patients. A Prospective Randomized Study

Dube S, Tyagi M, Chaturvedi A. AIIMS, New Delhi, India

Background: Intraoperative fluid therapy can be challenging in aneurysmal subarachnoid haemorrhage (aSAH) patients because of preoperative fluid deficit, intraoperative blood loss/ blood transfusion and associated complication like stunned myocardium, and neurogenic pulmonary edema. Hence use of intraoperative goal directed fluid therapy (GDFT) is desirable in these patients. Studies comparing intraoperative conventional vs. GDFT in patients with intracranial aneurysm are scarce. So, we compared conventional vs. GDFT regimen in patients with aSAH.

Methods: Sixty patients undergoing aneurysm surgery were randomized into conventional fluid therapy (Group S) and GDFT(Group G) group. In group G fluid administration was as per a pre-set protocol.(1) parameters, fluid/vasopressors/ inotropes used and duration of surgery/anesthesia were recorded. Postoperative complications, length of ICU and hospital stay, and neurological outcome at discharge (modified rankins scale) was compared.

Results: The two groups were comparable in terms of demographic variables. Intraoperative total fluid administered as well as volume of both crystalloid and colloid were significantly lesser in group G (Table 1). Duration of ICU (3±1.57 d vs 4.5±2.88 d; P=0.016) and hospital (6.4±2.55 d vs 8.73±4.11 d; P=0.011) stay was lesser in Group G . However, Group S patients had significantly higher incidence of post-operative seizure (Table 2). Neurological outcome was significantly better in group G. Other neurological and non-neurological complications and 30 days mortality was similar between the two groups.

T7
TABLE 1:
Perioperative Data
T8
TABLE 2:
Post-operative Complication

Conclusion: Intracranial aneurysm surgery patients receiving goal directed fluid therapy had significantly lesser length of ICU/ hospital stay and better neurological outcome as compared to patients receiving fluid as per conventional fluid regimen.

[SNACC-64] Intraoperative Management of Suboccipital Craniotomy in a Patient with Primary Aortic Arch Angiosarcoma

Bradley D, Welch T, Armour S. Mayo Clinic, Rochester, Minnesota, United States

Introduction: Angiosarcomas are malignant vascular endothelial cell tumors, representing 1-2% of sarcomas with an incidence of 1:1,000,000 in the United States. There is a paucity of literature on these tumors, especially aortic arch tumors, with approximately 40 unique cases published. Once metastatic they have a median survival of 12–16 months. Management is frequently complicated by coagulopathy, anemia, distal claudication, and embolic events; all which can be exacerbated in the peri-operative period. [1] We present a case of a patient with aortic arch angiosarcoma undergoing suboccipital craniotomy via prone positioning for decompression of an acute posterior fossa subdural hematoma.

Case Report: A 64-year-old female was admitted for evaluation of recurrent syncope, weakness, and right leg claudication in the setting of a newly aortic arch mass and osteolytic lesions in the posterior fossa. Due to discovery of subacute right leg embolic thrombus she was placed on heparin infusion, and on hospital day 8 she developed headache, nausea, and vomiting. Non-contrast head CT showed acute right cerebellar subdural hematoma. She was taken emergently to the operating room for suboccipital craniotomy for decompression. Pre-op labs were remarkable for hemoglobin 8.1, platelet 359, and PT 15.4/INR 1.4. Cardiac CT, MRI, and TTE were reviewed showing a shaggy, lobular, and partially mobile mass in the distal aortic arch from the brachiocephalic to high descending aorta causing mild to moderate luminal stenosis, there was no concern for resting obstruction. Upon entering the OR, she was vomiting and in acute distress. Vital signs showed BP 190/70, HR 80-80. The patient was induced with propofol, fentanyl, lidocaine, and rocuronium, and the airway was secured via rapid sequence intubation with a videolaryngoscope. Additional IV access and right radial and left femoral arterial catheters were obtained to aid with pre/post-aortic lesion hemodynamic monitoring given possibility of dynamic obstruction with prone positioning. Consideration was made for TEE and NIRS monitoring to assist with hemodynamic evaluation and monitoring for embolic phenomenon respectively, but due to prone positioning were not utilized. Transition to the prone position resulted in hemodynamic lability with systolic blood pressure fluctuating between 190 and 120mmHg, which improved with volume resuscitation and phenylephrine administration. The surgical team successfully decompressed the posterior fossa hemorrhage. The patient was extubated, taken to PACU for recovery, and transferred to the neurologic ICU with no neurologic changes. The posterior fossa mass was biopsied which confirmed the diagnosis of metastatic angiosarcoma.

Discussion and Conclusions: This case describes the peri-operative considerations to manage a patient with an intra-aortic mass superimposed on the hemodynamic considerations of prone positioning, acute intracranial hemorrhage, and suboccipital craniotomy. There are no other case reports to guide management of aortic arch obstructive pathologies such as angiosarcomas or aortic coarctation in this setting. With aortic arch masses, hemodynamic goals include optimizing preload, maintaining contractility and heart rate and avoiding excessive changes in afterload. Even if there is no evidence of resting obstruction, dynamic changes can occur during the transition to prone position with increase in afterload, suppressed cardiac output, and preload reduction. [2] In cases like this, preload optimization prior to prone positioning may minimize hemodynamic derangements. Preparation for significant decreases in cardiac output and development of hypotension with vasopressors available prior to the position change. These derangements have the potential to become even more hemodynamically significant in lesions with flow obstructions at baseline (Fig. 1 and 2).

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FIGURE 1:
Cardiac MRI coronal view of aortic arch mass measuring approximately 2.5 cm×2.5 cm in this plane.
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FIGURE 2:
Cardiac MRI sagittal view of aortic arch mass measuring approximately 5 cm×2.5 cm in this plane.

[SNACC-65] Intraoperative Neurophysiology Monitoring for Microvascular Decompression of the Facial Nerve

Salinas S, Paisansathan C. University of Illinois – Chicago, Chicago, Illinois, United States

Introduction: Hemifacial spasm is a neuromuscular disorder characterized by involuntary contractions of unilateral facial muscles. Ocular muscles are commonly involved, leading to persistent eye twitching that decreases quality of life. This disorder may be caused by vascular compression of the facial nerve at the root exit zone, leading to hyperexcitability of the nerve and involuntary contractions of facial muscles. Microvascular decompression is the gold-standard treatment for hemifacial spasm, as it relieves pressure from vessels on the nerve root. Lateral spread response is the abnormal electrophysiological characteristic of HFS. Neurophysiologic monitoring modalities can be used for intraoperative monitoring of sensory/motor nerve function, the offending vessel(s) causing the MVD, and to suggest an appropriate surgical end point. In particular, facial nerve EMG can show disappearance of LSR after adequate decompression of the facial nerve from neurovascular contact during the surgery.

Case Description: 54-year-old female presented with left hemifacial spasm for four years. She received Botox injections previously to relieve the spasm, but this was not adequate, necessitating surgical intervention. Anesthesia was induced with fentanyl, propofol, succinylcholine, and it was maintained using total intravenous anesthesia with remifentanil and propofol infusions. No muscle relaxant was used as this would impair accuracy of motor nerve monitoring. Following induction, the electrophysiologist placed various electrodes for monitoring of both sensory and motor nerve function. Unique to this specific surgery, facial nerve lateral spread response was assessed intermittently from the zygomatic and mandibular branches of the facial nerve. MVD was performed via retrosigmoid approach. The neurosurgeon dissected down to the cistern of the cerebellopontine angle and identified the 7th/8th CN complex, where they identified an artery wrapping around the complex. They dissected the vessel from the nerve and pulled out the vascular loop of the anterior inferior cerebellar artery (AICA). They placed Teflon pledgets around the AICA and CN complex, protecting all surfaces of the nerve. Prior to decompression, polymorphic LSR was seen from the zygomatic and mandibular stimulation (baseline). Following the MVD, there was an absence of the polymorphic LSR to threshold stimulation, indicating successful decompression. The patient recovered in the NSICU for several days, noting postoperative improvement of HFS prior to discharge.

Discussion: Two theories can be used to explain the phenomenon of hemifacial spasm. The central origination theory proposes that hemifacial spasm is due to the hyperexcitability of the motor nucleus of the facial nerve, while the peripheral origination theory considers that vascular compression of CN VII at the REZ leads to erratic transmission and myelin injuries (Song 6121). MVD surgery was developed as treatment for HFS based on the peripheral origination theory. The existence of LSR indicates the existence of abnormal cross connections between facial nerve branches. Intraoperative LSR monitoring can provide objective evidence to confirm the identity of offending vessels: if LSR disappears after a suspected vessel is detached from the facial nerve, the vessel can be confirmed as the offending vessel, but if the LSR persists, there may be other offending vessel(s). During MVD, the LSR usually disappears after insertion of Teflon pledgets. The most common offending vessels in HFS are the AICA, as seen in this patient’s case, and the posterior inferior cerebellar artery (PICA). Although intraoperative LSR monitoring can help guide MVD and predict surgical outcomes, the outcomes of HFS are multifactorial and LSR therefore cannot be used as the sole criterion for prognostic evaluation.

Song, Hongmei, Xu, Songbai, et al Prognostic Value of Lateral Spread. https://journals.sagepub.com/doi/full/10.1177/0300060519839526.

Kim, Minsoo, et al “Lateral Spread Response of Different Facial Muscles during Microvascular Decompression in Hemifacial Spasm.” Clinical Neurophysiology : Official Journal of the International Federation of Clinical Neurophysiology, Oct. 2021, https://pubmed.ncbi.nlm.nih.gov/34454279/ (Fig. 1).

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FIGURE 1:
Polymorphic waveforms seen with lateral spread response, an abnormal electrophysiological response to stimulation of the facial nerve.

[SNACC-66] Investigating the utility of novel biomarkers which predict the onset of vasospasm after subarachnoid haemorrhage

Gardner A, Math N, Waraich M. National Hospital for Neurology and Neurosurgery, UCLH NHS Foundation Trust, London, United Kingdom

Introduction: The onset of vasospasm after subarachnoid haemorrhage (SAH) is often insidious. The pathogenesis of this phenomenon has yet to be resolved, though a proinflammatory endothelial reactivity is hypothesised, which results in vasoconstriction. Vasospasm is highly predictive of delayed cerebral ischemia (1), so its early identification is crucial. However, no risk-scoring methodology has yet been established. Using a mechanistic rationale, we hypothesised that two biomarkers associated with endothelial reactivity may have utility: the white cell count (WCC) and brain-natriuretic peptide (BNP). Others have previously described their association with worse SAH outcomes (2,3). With three established risk factors (age, gender, smoking status), we considered these two novel predictors for inclusion into a predictive model of vasospasm.

Methods: Only the first WCC and BNP after neurocritical care admission were used to ensure biological relevance. Patients were excluded if they did not have both within 48 hours. Fisher’s Exact Test was used for frequency associations. WCC (×10^9/L), BNP (picograms) and age were classified into categorical variables (elevated, or not; >10, >400 or >55, respectively). Statistical significance judged as P=<0.05. Receiver operator characteristic (ROC) curves were used to classify BNP and WCC, with the area under curve (AUC) accompanied by a 95% confidence interval. Binary logistic regression of these variables was used to generate a composite predicted likelihood of vasospasm.

Results: Over 12 months, all 85 patients admitted with SAH were screened for inclusion in the analyses. Of these, only 38% (32) were eligible owing to missing data; no patient developed vasospasm within 48 hours of admission. Of the five tested predictors, BNP and WCC were significantly associated with future vasospasm, while age, gender and smoking status were not. The median admission BNP and WCC was 1309 and 14.1 in those who developed vasospasm, and 315 and 10.7 in those who did not. As continuous variables, WCC and BNP classified the onset of vasospasm with statistical significance and good accuracy, with an AUC of 0.801 (0.652 to 0.949) and 0.763 (0.591 to 0.935), respectively. A threshold WCC of 10 predicts future vasospasm with 95% sensitivity and 50% specificity, whilst a threshold of 12, 74% sensitivity and 64% specificity. For BNP, a threshold of 400 predicts future vasospasm with 81% sensitivity and 60% specificity, whilst a threshold of 600, 66% sensitivity and 71% specificity. Using both biomarkers, classification using a composite ‘predicted probability’ performed better, with an AUC of 0.853 (0.724 to 0.982) (Fig. 1).

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FIGURE 1

Conclusion: An initial elevated WCC and BNP were individually associated with the onset of vasospasm, with robust sensitivity and specificity. Used together, they may have increased utility to either one individually. Included with a risk scoring system, they may help to better identify those patients at risk of vasospasm.

[SNACC-67] Is Goal Directed Fluid Therapy Superior To Conventional Fluid Therapy In Isolated Traumatic Brain Injury Patients Undergoing Surgical Intervention - A Prospective Randomized Controlled Trial

Hazarika A, Junghare P, Bhatia N, Kaloria N. Postgraduate Institute of Medical Education and Research, PGIMER, Chandigarh, India

Background: Goals of fluid therapy in TBI are to preserve cerebral perfusion and ensure appropriate substrate. These patients are prone to osmotic and electrolyte disturbances.Goal directed therapy(GDT) based on dynamic parameters (SPV, PPV,CI, SVV) derived from arterial waveform has improved outcome in surgical patients. However their is paucity of data in TBI patients undergoing surgery.

Objectives: Primary: To compare GDT and conventional hemodynamic based therapy on total intra-operative fluid administered during decompressive craniectomy. Seconadary: To compare total blood loss, lactate, urine output, hematocrit, use of vasoactive drugs,FOUR score when patient on ventilator, days in ventilator and GOS at three months post discharge.

Methods: Adult patients with TBI posted for decompressive craniectomy were randomly allocated into two group. Goal directed fluid therapy (GDT) group: Flo Trac, EV-1000 device (Edwards Lifesciences, Irvine, CA) to monitor SVV, CI and MAP. Targets to be achieved/ maintained: SVV <=12%, CI >=2.5 L/min/m2, MAP >=70 mm of Hg. If the MAP consistently <70 mm of Hg and the CI >=2.5 L/min/m2, continuous phenylephrine infusion was started to achieve target MAP. Conventional fluid therapy (CFT) group: Fluid infused at a rate of 2 mL/kg/h with target MAP >70 mm of Hg.

Results: 64 adult patients were randomly allocated into two group. There was no significant difference in the mean total fluid administered (2567.81 mL vs 2670.62 mL) (P-0.51) (Fig. 1). Also no significant difference in intraoperative blood loss ,urine output, lactate levels, haematocrit levels, ventilator days. Average FOUR score (P-0.172) and GOS at 3 months post discharge (p-0.58) were comparable. Overall mortality was 4 in group GDT (12.5%) and 7 patients in group CFT (21.8%).

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FIGURE 1:
Showing the results of the primary and secondary objectives.

Conclusion: Mean total fluid administered in both the groups was comparable with no significant difference in secondary outcomes.However their was a decline in mortality in goal directed fluid therapy group. No superiority of GDT over CFT was observed.

[SNACC-68] Isoflurane Anesthesia is Sexually Dimorphic Both in Mice and Humans

Wasilczuk A, Rinehart C, Aggarwal A, Proekt A, Kelz M. University of Pennsylvania, Philadelphia, Pennsylvania, United States

Sex-hormone expressing hypothalamic neurons have been recently shown to play a role in the sexually dimorphic responses towards modulation of the arousal state. (1,2) However, it remains unclear whether there are sex-based pharmacodynamic differences in anesthetic sensitivity. While not all clinical studies agree, ample evidence suggests females are predisposed to a higher incidence of intraoperative awareness with recall. Despite this, the use of intraoperative brain monitoring fails to reliably reduce cases of awareness in both sexes. One possible explanation for sex-based differences in anesthetic sensitivity not captured by the cortical EEG could be that critical subcortical neuronal sites may influence arousal indirectly. We hypothesized that at steady state levels of isoflurane anesthesia, there would be sex-based differences in isoflurane sensitivity both in mice and humans due to differential contributions of sex hormones. Moreover, we hypothesize that sex based differences would not be distinguished by cortical measures of brain activity but would be associated with changes in activity of subcortical nodes.

Using intact adult and surgically gonadectomized C57BL/6J mice, we demonstrate that female mice are more resistant to inhaled anesthetics than males. Castration produces female-like resistance to isoflurane while ovariectomy in females does not change sensitivity. Supplemental administration of testosterone or estradiol increases isoflurane sensitivity while administration of letrozole, an aromatase inhibitor, causes acute resistance to isoflurane. No detectable sex differences were observed in spectral power or in burst suppression measures of EEG recorded at steady state isoflurane exposure across multiple drug concentrations. Whole brain c-Fos imaging of mice exposed to 4 hours of steady state levels of isoflurane anesthesia revealed differential c-Fos expression in hypothalamic nuclei.

A new analysis of our controlled clinical trial in healthy human volunteers given a deep isoflurane anesthetic without any surgical intervention (3) supported our sexually dimorphic anesthetic sensitivity findings in mice. We demonstrate that healthy human females emerge faster and exhibit faster cognitive recovery than males, with no sex differences observed in EEG derived measures. We demonstrate that there is a sex dependent effect on anesthetic sensitivity at steady state exposure to isoflurane anesthesia. Sex hormones may contribute to the differences observed in anesthetic sensitivity. Further, sex specific effects on anesthetic potency may clarified by differential neuronal activity patterns in the ventral preoptic hypothalamus. Cumulatively, these results suggest that sex is an underappreciated determinant of anesthetic sensitivity. Sex-based differences in drug potency should be considered during anesthetic exposures.

[SNACC-69] Ketamine dissociation triggers a universal switch in excitatory neuronal activity across neocortex

Cichon J, Contreras D, Kelz M, Looger L, Proekt A. University of Pennsylvania, Philadelphia, Pennsylvania, United States

The brain can become transiently disconnected from its surrounding environment while maintaining vivid, internally generated experiences, the so-called ‘dissociated state,’ under severe stress, trauma, psychiatric disorders, epilepsy, psychedelics, and the anesthetic ketamine. Cellular and circuit mechanisms underlying the dissociative state, however, remain unknown. We show that ketamine’s dissociative state accompanies a cortical network switch – active neurons become suppressed while previously silent neurons become activated. This switch in the active neuronal population occurs across all cortical layers and different cortical regions. Cortical application of ketamine mimics effects of systemic ketamine and recapitulates behavioral features of the dissociative state, suggesting a neocortical mechanism. Suppression of parvalbumin and somatostatin interneuron activity, and inhibition of NMDA receptors and HCN channels, underlie the neuronal switch. Combined, our results reveal two largely non-overlapping distributed neuronal populations in the neocortex: one engaged in wakefulness/sensory processing, the other underlying the dissociative state. Thus, we provide a novel mechanism for the dissociated state and lay the foundation for an understanding of how the brain might become disconnected from sensory stimuli while maintaining internal subjective experiences.

[SNACC-70] Lactated Ringer’s Versus Normal Saline (0.9%) for Perioperative fluid administration in Pediatric Patients Undergoing Neurosurgical procedures: A Pilot Trial

Depuru A, Jangra K, Bhagat H, Lal Soni S, Singla N, Prabhakar A. Postgraduate Institute of Medical Education and Research, PGIMER, Chandigarh, India

Background: Fluid management in perioperative phase presents unique concerns for children undergoing surgery. Maintaining osmolarity is critical in maintaining normal environment, in neurosurgery patients. Intraoperatively, Lactated Ringer’s (LR) and 0.9 percent sodium chloride solution (NS) are two common intravenous fluids (IV) in pediatric patients. LR has a serum osmolarity of 273 mOsm/L, which is slightly hypo osmolar in comparison with NS and an osmolality of 255 mOsm/kg. However, when assessed by the depression of freezing point, it drops to 254 mOsm/kg for LR and stays same for NS. This is because LR solutes have incomplete ionization while NS solutes have more complete ionization.

Literature regarding the type of fluid to be used in pediatric neurosurgical patients is very sparse. Most experts prefer using NS over LR because of the theoretical risk of hypo-osmolarity as found in animal studies but clinical studies are lacking. Hence, this study was planned to compare the commonly used solutions, NS and LR during pediatric neurosurgical procedures. Primary outcome was the absolute difference in serum chloride concentrations (post-preoperative ΔCl−) measured after surgery and at baseline. Secondary outcomes included the post-preoperative difference of other electrolytes and osmolarity, postoperative acidosis, rise in creatinine and the brain relaxation score (BRS), neurological outcome at discharge measured by modified Rankin scale (mRS).

Methods: This prospective randomised trial was conducted after getting approval from the Institutional Ethics Committee, and parent/guardian written informed consent. Study included ASA status I and II children, aging between 6 months to 14 years, of either gender, who were scheduled to undergo decompressive craniectomy for elective neurosurgery under general anesthesia. Participants were excluded following refusal of consent, pre-existing electrolyte abnormalities, and severe major organ dysfunction. Forty patients were enrolled and randomized as per computer-generated random number table into two groups, group-S and group-R with 20 patients each. Patients in group S received 0.9% Saline, group R received LR. Fluid therapy was guided by Pleth Variability Index (PVI) before insertion of invasive line and systolic pressure variations (SPV) after insertion of arterial line. Target PVI was 13%, any decrease was supplemented with small boluses of 5 mL/kg till the target blood pressure appropriate for the age was achieved. Blood and blood products were given once Maximum Allowable Blood Loss (MABL) is reached. Arterial blood samples were taken; each at the start of surgery, during tumor resection, at the end of surgery and 24 hours post surgery. ABG parameters were recorded, along with monitoring of vitals, fluid input, and output charting.

Results: Difference in chloride levels (postoperative - preoperative) ΔCl was (Median, Interquartile range) 12[9-16] mmol/L in NS group versus 4[2-15] mmol/L in LR group; P=0.03. There was no significant difference in values of other electrolytes between the two groups. Δ Osmolarilty was (mean±SD, NS versus LR) 3.38±8.93 mOsm/L versus 1.00±7.36 mOsm/L; P=0.36. Incidence of postoperative acidosis was (NS versus LR) 33.3% vs 21.05%; P=0.38. None in NS group had Brain relaxation score (BRS) >2, however 15.8% in the LR group had BRS >2; P=> 0.05. There was no difference in perioperative creatinine change between the groups Δ Creatinine (mean±SD, NS versus LR, 0.01±0.16 mg/dL versus 0.03±0.16 mg/dL; P=0.658). All patients had MRS<2 in LR while 9.5% in NS group had MRS >2, P=0.168.

Discussion: Normal saline increases perioperative chloride more than Lactated Ringer’s in children undergoing neurosurgical procedures. However, there was no difference in the incidence of postoperative acidosis. LR can also be administered in pediatric neurosurgical population, however further multicentric studies are required.

[SNACC-71] Large Occiput to Thoracic Fusion Extension in a Patient with Goldenhar Syndrome (Case Report)

Gottwald J, Kerfeld M. Mayo Clinic, Rochester, Minnesota, United States

Goldenhar syndrome is one of many congenital syndromes that can pose challenges to delivery of safe anesthetic care. This is particularly relevant when considering the potential acquired comorbidities that can be associated with various conditions. Goldenhar syndrome is associated with abnormalities of the head and neck related to abnormal formation of the first and second branchial clefts during development. The spine can also develop significant abnormalities of immaturity and instability, potentially resulting in the need for spine surgery to treat symptoms and provide support. In this case report we describe a 50-year-old female presenting for elective posterior cervicothoracic spinal fusion from the occiput to T9 for myelopathy. The patient had multiple prior surgeries including suboccipital decompression, C1 laminectomy and extension of prior fusion from occiput to T8 for myelopathy and C1-2 instability (Fig. 1). The patient had Goldenhar syndrome and notable abnormal facies in addition to no ability to extend or rotate her neck. Her neck landmarks for potential surgical airway and vascular access were distorted. She was a known difficult airway with prior failed awake fiberoptic intubation (FOI); she successfully underwent a controlled asleep fiberoptic intubation with video laryngoscopy assistance for pharyngeal tissue movement for her most recent surgery. For this case we proceeded with a planned awake FOI with dexmedetomidine, midazolam and oropharyngeal topicalization. Initial attempts in the supine position were unsuccessful. Despite repositioning and trialing awake video laryngoscopy assistance we were not successful with intubation due to immobility of the cervical spine and prominent protrusion of the posterior oropharynx obstructing the glottic inlet. With surgical backup we elected to perform a controlled asleep FOI with video laryngoscopy and significant jaw thrust with adequate visualization of the glottic inlet and successful endotracheal intubation. We elected to perform femoral central venous access due to unsatisfactory ultrasound evaluation at the level of bilateral internal jugular veins. Radial arterial access was obtained for hemodynamic monitoring. Once airway and access were secured, general anesthesia was maintained with propofol and sufentanil infusions. Neuromonitoring with motor and somatosensory evoked potentials were utilized for the duration of the case. We utilized a continuous phenylephrine infusion as needed to maintain a target mean arterial pressure of 70 mmHg. Intraoperatively a pre-existing cerebrospinal fluid (CSF) leak in the occipital area was discovered and repaired. Evoked potentials were largely stable throughout the case. Estimated blood loss was limited to 350 milliliters. The complex nature of the closure required flap placement by plastic surgery. A lumbar drain was placed postoperatively for intracranial pressure monitoring and management. She was transferred intubated to the intensive care unit for recovery. On post-operative day two she had evidence of ongoing CSF leak at the level of the odontoid which required endoscopic repair. On post-operative day six she returned to the operating room for confirmation of CSF leak repair and controlled extubation over a Cook exchange catheter.

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FIGURE 1:
Preoperative 3D reconstruction of the cervical anatomy and prior hardware.

[SNACC-72] Loss of Signals During Pediatric Scoliosis Correction

Leeds M, Dejoy S, Hambley M. Metrohealth Medical Center, Cleveland, Ohio, United States

Background: Our patient is an 11 year old female with juvenile idiopathic scoliosis of her thoracolumbar spine. She has no other past medical history and is otherwise healthy. Preoperative history and physical did not reveal any cardiovascular or pulmonary deficiencies caused by her scoliosis. Radiographic images demonstrated left upper thoracic curve of 45°, a right main thoracic curve of 72°, and a 54° left lumbar curve. The surgical team was performing a posterior spinal fusion from T3-L3 utilizing neuromonitoring of both Somatosensory Evoked Potentials(SSEPs) as well as Motor Evoke Potentials (MEPs.)

Anesthetic Plan: Our plan, developed in conjunction with the surgical team was general anesthesia with endotracheal intubation and total intravenous anesthesia. Induction was performed with ketamine, fentanyl, lidocaine, and propofol; and maintenance of anesthetic depth was performed with infusions of propofol and remifentanil. We opted for this plan because maintenance with volatile anesthetics and the use of paralytics would have limited the ability of our neuromonitoring team to obtain reliable data intraoperatively. Our patient was positioned in the prone position so we had to ensure little movement.

Case Details: Induction and intubation were without complication and baseline SSEPs and MEPs were obtained. The surgeons exposed the patient’s spine and placed screws from T4-L3, while continuous SSEPs and MEPs remained normal. Ponte osteotomies were carried out from T5-L1 for further correction. Then, a right sided rod was placed without complication. Upon placement of left sided rod and bend to correct our patient’s right sided rib hump, our neuromonitoring team noted an abrupt decrease in lower extremity SSEPs and MEPs, indicated by a major increase in latency and decrease in signal amplitudes.

At this time, efficient interpersonal communication was essential, as we needed to diagnose and treat the cause of the loss of signals. We confirmed that anesthesia was maintained at a steady state and no boluses of medications were given that could alter signals, and in order to maintain perfusion to the nerve roots, we raised our MAPs(which were already maintained in the 80s) using fluid and pressors. An Arterial blood gas was also drawn to determine oxygen carrying content of blood and any acid-base abnormalities. The signals did not return, so the decision was made to remove the surgical rods. Upon removal of the rods, SSEPs and MEPs returned to the patient’s baseline.

Re-instrumentation was then attempted, with less correction and both the SSEPs and MEPs remained at baseline. The remainder of the case proceeded uneventfully and upon emergence from the case a full neurological examination was performed on the patient which revealed lower extremity strength and sensory function fully intact.

Discussion: Scoliosis is a lateral curvature of the spine, measured by the Cobb angle(the intersection of parallel lines from end plates of superior and inferior end vertebrae.) Children diagnosed with Juvenile Idiopathic Scoliosis often see a progression of the disease throughout childhood, and after maturity usually at a rate of 1 degree per year. The curvature can have physiological effects, leading to cardiovascular and pulmonary issues, as well as phycological effects for a young child. Treatment can involve conservative measures, or in severe cases, such as when the Cobb angle is greater than 40 degrees, surgical correction. During surgery, neuromonitoring is essential to quickly diagnose and correct any potential disastrous outcomes for the patient. Monitoring evoked potentials can realize a significant increase in latency, measured above 10% of baseline, or significant loss in amplitude measure below 50% of baseline. This continuous monitoring is of utmost importance for positive patient outcomes (Fig. 1 and 2).

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FIGURE 1:
This image of shows the MEP signals after the rods were torqued within the patient.
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FIGURE 2:
This image of shows the SSEP signals after the rods were torqued within the patient.

[SNACC-73] Magnet Activation of Vagal Nerve Stimulator for Differentiation and Termination of Post Operative Epileptiform Seizure

Lyes M, Filipovic M, Fejleh A, Tran M, Pearn M, Lemkuil B, Krause M, Ben-Haim S, Srejic U. UCSD Health, San Diego, California, United States

In the post operative period, generalized shaking associated with emergence is common and sometimes confused for seizure activity. While post operative seizures are rare in non-predisposed individuals, nonepileptic psychogenic seizures (pseudoseizures) occur more frequently and are often misdiagnosed. Similarities in symptomatology make differentiating psychogenic and epileptiform seizures a challenge, especially in patients with comorbid disorders. For patients with intractable epilepsy, implanted vagal nerve stimulators (VNS) can offer relief through baseline stimulation and often contain a magnet feature that can be activated to abort a seizure or lessen the severity. This case report highlights the utility in VNS magnet activation to terminate epileptiform seizures while differentiating them from other causes of generalized shaking.

A 35-year-old female with history of intractable epilepsy since birth in the setting of cerebral palsy and Lennox-Gestaut syndrome presented for VNS battery replacement. Her seizures localize to the left temporal lobe on EEG, occur with prodromal aura and manifest as right upper and lower extremity convulsions and paresthesia. Although VNS implantation dramatically reduced seizure frequency, a recent traumatic family event triggered new onset pseudoseizures that occur three to ten times per day. The manifestation of these events is distinct from her epileptiform seizures, lacking tonic-clonic qualities and characterized by whole body rocking and absence with disorientation and dissociation.

On the day of surgery for VNS battery replacement, she underwent a straightforward sevoflurane based general anesthetic. She was extubated awake in the OR and on transfer to recovery, became confused and nonresponsive, with rhythmic head movement, a stiff right arm and clenched fist. Given the presence of a functional VNS and known frequency of psychogenic seizures, bedside providers initially reasoned a pseudoseizure was likely triggered by anesthetic emergence. BIS readings were uninterpretable due to motion artifact and with persistent symptoms after one minute, IV lorazepam was administered without any apparent effect. The patient’s mother was brought to bedside and recognized this behavior as an epileptiform seizure. She swiped a magnet across the stimulator pocket resulting in immediate seizure termination and return of consciousness.

For patients with underlying epilepsy, the likelihood of post-operative seizure is increased, while in susceptible individuals, pseudoseizures can be provoked simply by the stress of anesthetic emergence. Although VNS provide their own output to terminate an epileptiform seizure, the effect can be augmented by triggering the device with a magnet. Widespread knowledge of this feature for those with implanted VNS can be a useful tool for distinguishing psychogenic and epileptiform seizures, ultimately avoiding unnecessary administration of medication or delay in treatment (Fig. 1).

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FIGURE 1:
Wearable Vagal Nerve Stimulator Magnet.

[SNACC-74] Management of coagulopathies in patients with liver disease and intracranial haemorrhage

Chavali S, Kanasani S, Raju S. AIG Hospitals, Hyderabad, India

There is a significantly increased risk of intracranial haemorrhage in patients with liver disease. Management of such patients is complex, especially given that patients with chronic liver disease (CLD) suffering from intracranial bleeds that require neurosurgical intervention usually present with deranged coagulation profiles such as increased prothrombin time, reduced fibrinogen and thrombocytopenia. Conventionally, neurosurgery in this patient cohort is preceded by complete correction of coagulation parameters, which may involve transfusion of large volumes of fresh frozen plasma, cryoprecipitate, and platelets, which is both time as well as resource - consuming. There is a recent understanding that patients with liver cirrhosis live in a state of dynamic hemostasis, which results in a net prothrombotic state, often achieving hemostasis despite elevated INR values. In this case series, we reviewed clinical outcomes in such patients who were operated upon with deranged values in conventional tests of coagulation, but with normal reports in viscoelastic assays of coagulation. We performed a single-institution review of patients suffering from chronic liver failure who presented with neurological emergencies and deranged coagulation profiles. Based on their outcomes, it is seen that these patients had successful neurological surgeries despite conventionally unacceptable parameters of coagulation.

[SNACC-75] Massive Brain Swelling After Cranioplasty: Could Anesthesia Play a Role?

Brosnan H, Abramowicz E. Westchester Medical Center/New York Medical College, Valhalla, New York, United States

Cranioplasty following decompressive craniectomy is a step towards recovery.1 Although considered a low-risk surgery, complications occur in up to 40% of cases, including infection, graft resorption, and hematoma.2, 3 Occurring in up to 2.4% of cases, massive brain swelling after cranioplasty (MBSC) is among the most catastrophic complications, resulting in death or permanent disability.3 While the etiology of MBSC remains unknown, preoperative sinking skin flap syndrome, use of negative pressure drains, and autoregulatory dysfunction may play a role.2, 3 Limited studies and case reports on MBSC focus on patient and surgical risk factors - there are currently no studies examining the role of anesthesia on MBSC. With the goal of improving safety for patients undergoing anesthesia for cranioplasties, we reviewed the anesthetic records of four patients who developed MBSC at our institution to determine if elements of anesthetic care may have an impact on the development or prevention of this complication. A review of complications following cranioplasties found four patients who had developed massive cerebral edema following cranioplasty (Table 1). The patients ranged in age from 25-58, three initially presented with traumatic brain injuries (TBI) and one with a stroke, and all had decompressive hemicraniectomies (DHC). Three patients had cranioplasty within 3 months of DHC, the fourth patient was 3 years out and undergoing his third cranioplasty after a recurrent infection had necessitated prior reversals. All four patients underwent general anesthesia using sevoflurane, three received synthetic grafts, one autologous, and sub-galeal drains were placed in each case. IV fluid administration, estimated blood loss, and urine output were within routine values. Two patients received intraoperative mannitol. Three patients had midline shift prior to cranioplasty (the fourth patient did not have recent imaging). One patient had confirmed sinking skin flap syndrome and a second likely had it based on imaging. Among the anesthetic variables reviewed, we were interested in those that impact cerebral blood flow, particularly in the setting of impaired autoregulation, including blood pressure trends and ETCO2 levels. Three patients required antihypertensive medications. Two patients became acutely hypertensive following emergence, both of whom were immediately given opioids and antihypertensives. The onset of hypertension coincided with other signs of increased intracranial pressure (ICP), including fixed dilated pupils and a seizure suggesting an etiology for hypertension. The third patient was both hypertensive and hypercapnic during emergence and was given metoprolol with resolution of high blood pressure. He was transported to PACU, although “sleepy”, he received no additional intervention. Shortly thereafter, he was found to be hypertensive and bradycardic, likely from increased ICP from cerebral edema. In the other cases, ETCO2 levels were within normal limits. A review of these four cases suggests areas where anesthetic management may either mitigate risk of MBSC or indicate impending MBSC. Severe cerebral injury secondary to TBI or anoxic insult disrupts normal autoregulation, rendering patients vulnerable to injury from hyper- and hypotension, hypercapnia, and fluid shifts. While cranioplasties are performed once patients have recovered from the acute phase of their injury, this does not guarantee return of normal autoregulation. From an anesthetic standpoint, tight control of blood pressure, arterial or ETCO2, and intrathoracic pressures may help decrease the risk of MBSC. In patients with known autoregulatory dysfunction, avoidance of high volatile concentrations may also be considered. Caution should be taken to avoid large fluid shifts with crystalloids, hypertonic saline, mannitol, or albumin. Providers should remain vigilant for acute hypertension, which necessitates an immediate physical exam to look for signs of increased ICP. Patients with sunken flap syndrome or those in whom a negative pressure drain was placed should be considered at higher risk for MBSC (Fig. 1).

T9
TABLE 1:
Summary of Patient Characteristics and Anesthetic Variables of Four Patients Who Developed Massive Brain Swelling After Cranioplasty
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FIGURE 1:
CT head images of the same patient. (A) CT Head after a decompressive hemicraniectomy with 2mm left-to-right midline shift attributed to volume retraction. (B) CT Head immediately after cranioplasty showing diffuse cerebral sulcal effacement secondary to cerebral edema, 2.3 cm left-to-right midline shift, near-complete effacement of the left lateral ventricle, and asymmetric enlargement of the right lateral ventricle.

[SNACC-76] Measurement of Transcranial Doppler Insonation Angles from Three-Dimensional Reconstructions of CT Angiography Scans

Leotta D, Sharma D, Anderson M, Straccia A, Zierler R, Aliseda A, Sheehan F. University of Washington, Seattle, Washington, United States

Background: The blood velocities measured by Transcranial Doppler (TCD) are dependent on the angle between the incident ultrasound beam and the direction of blood flow (known as the Doppler angle). However, TCD examinations are generally performed without imaging so that the Doppler angle for each vessel segment is not known. We have measured Doppler angles for the main arteries examined with TCD using three-dimensional (3D) vessel models generated from computed tomography angiography (CTA) scans. Knowledge of the distribution of the angles between the transmitted ultrasound beam and the blood vessel axis provides an understanding of the deviation that can be expected between the measured and true velocities in the targeted arteries.

Methods: We have reconstructed 3D vascular geometric models from CTA scans as part of a project to develop an interactive TCD training simulator that combines computational vascular flow models with a physical model of the head and a virtual ultrasound probe to replicate the TCD scanning procedure. Using these vascular models, we have compiled Doppler angle measurements for the main arteries examined with TCD for 24 vasospasm patient cases. A spatial transformation registers standard acoustic windows (Temporal, Sub-occipital, Sub-mandibular, and Orbital), which were previously defined for the TCD simulator, with their corresponding head locations for each patient. This produces data sets that allow measurement of Doppler angles based on the specific anatomy of each patient. Each acoustic window is defined by a ring of points that encompass the allowed examination window and the centroid of these points (Fig. 1a). For each vasospasm case, we generate virtual ultrasound transmit beams that originate from the acoustic window and intersect each vessel segment at sub-millimeter steps along the vessel center axis (Fig. 1b). Doppler angle measurements for the centroid and perimeter of the acoustic windows were compiled and analyzed for each reconstructed vessel segment (Fig. 2). Analysis also includes the insonation depths of the arterial segments and separation of results into arterial sub-segments where appropriate (for instance, the A1 and A2 segments of the Anterior Cerebral Artery).

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FIGURE 1:
(a) Acoustic window perimeters are shown with the 3D mannequin head model for the Temporal (blue), Orbital (red) and Sub-occipital (black) windows. (b) Acoustic beams (yellow) are shown originating at the centroid of the left Temporal window and intersecting the left Anterior Cerebral Artery (green) at 1-mm steps along its center axis. The angle between the acoustic beam and the center axis defines the Doppler angle t each point along the vessel.
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FIGURE 2:
Table of Doppler angles for ultrasound beams originating from the centroid of the acoustic window that corresponds to the given vascular segment. The results are compiled for both right and left sides.

Results: A table of the Doppler angle results for insonation from the acoustic window centroid is shown in Fig. 2. The mean Doppler angles were smallest for the Ophthalmic Artery (mean 26.0 degrees) and largest for the terminal Internal Carotid Artery (mean 56.5 degrees). Results have also been compiled for the acoustic window perimeter, right and left sides, and vessel sub-segments.

Conclusion: This analysis uses 3D anatomical computer models to provide statistics on the TCD insonation angle that are not routinely accessible during clinical studies. These distributions of Doppler angle indicate the variability in velocity measurements that can be expected for the vessel segments evaluated with TCD, and may thereby assist in the interpretation of TCD examinations.

[SNACC-77] Meningioma Resection in a Patient with Coronary Artery Disease Soon After Drug Eluting Stent Placement Requiring Dual Antiplatelet Therapy

Narayan M, Riazuddin I, Narayan M, Riazuddin I, Rajan S. University of Texas Health Science Center at Houston, McGovern Medical School, Houston, Texas, United States

Background: Non-cardiogenic surgery within a year after percutaneous intervention (PCI) occurs in approximately 5-10% of patients. Contradicting guidelines between co-occurring conditions makes the decision to undergo surgery and optimal hemostatic management ambiguous. Here we present a medically challenging case of a meningioma resection in a patient who had recently undergone PCI, who intraoperatively had ST elevations on cardiac monitoring.

Case: A 68-year-old male, ASA Grade IV, with coronary artery disease and 5 drug eluting stents (DES), two placed 3 months prior, presented to the ED with 6 weeks of worsening left-sided weakness. The patient had been on daily DAPT (Aspirin 81 mg, Clopidogrel 75 mg) for 3 months. Brain MRI showed a 8.5 cm×5 cm fronto-parietal mass with broad dural attachment, edema, and a 9mm midline shift, consistent with a meningioma. Neurosurgical resection was planned, and both DAPT agents were stopped for 5 days, with close monitoring of platelets, Aspirin effect, and Plavix (Clopidogrel) effect, in order to minimize the risk of excessive blood loss. Preoperative labs (CBC, BMP, TEG) and baseline EKGs were obtained.

In the OR, the patient was placed on standard ASA monitors, including a 5-lead EKG. An arterial line was placed and connected to the HemoSphere advanced monitoring system to obtain parameters such as cardiac output (CO) and systemic vascular resistance (SVR). During the operative course, significant ST elevation was noted in leads II and aVF; however, the patient remained hemodynamically stable and CO remained within normal range. The surgery continued and the patient was extubated and taken to the PACU.

Postoperative labs revealed an increase in troponins, from 11 pg/mL at baseline to 34,192 pg/mL within 8 hours. Post-operative EKGs showed no acute abnormalities, an echocardiogram showed no new wall motion abnormalities, and the patient was asymptomatic. Due to the absence of ischemic symptoms, no empiric treatment was initiated. The patient maintained hemodynamic stability for the remainder of his hospital stay and was discharged after cardiac and neurologic monitoring for 7 days.

Discussion: This case highlights the challenge of conflicting guidelines in coexisting conditions. The American Heart Association recommends 6 months of DAPT after a DES placement, as premature cessation is the strongest predictor of stent thrombosis and subsequent ischemic injury. On the other hand, current guidelines for meningioma treatment recommend resection in large (>3 cm), symptomatic tumors with surrounding edema. Sole radiation therapy is not recommended in large tumors due to higher risks of post radiation complications. In most cases, the risk of stent thrombosis far exceeds bleeding complications, except for intracranial surgery where bleeding is equally fatal.

The main cause of acute coronary injury in the perioperative period is demand ischemia. Key physiologic goals include: low to normal heart rate to ensure proper coronary blood flow during diastole, normal to high blood pressure with a goal MAP within 120% of baseline, normal to high hemoglobin oxygen saturation, and normothermia, as shivering can increase cardiac oxygen demand. By contrast, in neurosurgery, slight hypothermia is preferred to decrease central metabolic rate and brain oxygen requirements. If ischemic changes are present on telemetry, treatment of any present tachycardia and hypotension is recommended, along with the use of nitroglycerin to increase coronary blood flow.

The challenge of the anesthesiologist in this case was navigating conflicting guidelines: 81.1% of meningiomas are benign, but resection is recommended if the tumor is large and patient is symptomatic, while neurologic surgery can only take place if both DAPT agents are stopped, which contradicts the 6 month recommendation after DES placement. Maintaining appropriate perfusion while balancing the risk of bleeding intracranially and stent thrombosis, and navigating ST changes intraoperatively made this a medically challenging case.

[SNACC-78] Neonatal propofol exposure, unlike sevoflurane, does not alter GABAergic inhibition or decrease social interactions in adulthood

Kass I, Cottrell J, Lin D, Liu J, Yau A. SUNY Downstate Health Sciences University, Rockaway Park, New York, United States

Introduction: The early developing brain is especially vulnerable to insults from different anesthetics, which can result in long lasting functional changes. Anesthetic targets include GABAA receptors, NMDA receptors and/or intracellular signaling pathways. The long-term functional changes after exposure to anesthetics during the neonatal period are not known. We compared the effects of early-life propofol and sevoflurane on excitatory-inhibitory balance and adult behavior.

Methods: Postnatal day 7 (P7) C57/BL6 male pups were exposed to either 2-2.3% sevo in a 40% oxygen (O2) 60% nitrogen (N2) gas mixture for 2 hours; or propofol (250 mg/kg i.p.). Blood oxygen levels were monitored with a pulse oximeter. Propofol is absorbed slowly after i.p. injection and complete anesthesia was maintained for 2 hours; oxygenation and heart rate were normal throughout the experiment. Behavior and electrophysiology were conducted when the mice were adults (2 mo old). The effect of the GABA agonist muscimol (3 µM) the GABA antagonist bicuculine (100 µM) and paired-pulse stimulation on Schaffer collateral stimulation of hippocampal slice CA1 neurons was used to measure inhibition or excitation of the extracellularly recorded field excitatory postsynaptic potentials (fEPSP). Behavior tests examined open field, novel object recognition, three chamber social interaction and novel mouse direct social interaction All statistics indicated are either t-test or 2-way repeated measures ANOVA with Bonferroni multi comparison; P<0.05.

Results: The effect of muscimol, an agonist of the inhibitory transmitter GABA, on the fEPSP demonstrated that adult mice treated with sevo at P7 had significantly less inhibition compared to no sevo treated mice; there was no significant effect of P7 propofol treatment. Sevoflurane, but not propofol demonstrated less paired pulse inhibition and greater excitation after the GABA antagonist bicuculine. There was no significant effect after P7 propofol treatment on either of these. P7 sevo treated mice showed significantly less time interacting with a novel mouse in a 3 chamber apparatus and in a cage where they could directly interact with the novel mouse, P7 propofol treatment did not affect these behaviors.

Conclusions: Neonatal sevo, but not propofol, treatment impairs the GABAA response, resulting in decreased inhibitory and increased excitatory synaptic transmission in adult mice. Neonatal sevoflurane had a greater effect on social interactions than propofol. Even though the general anesthetics sevoflurane and propofol both prominently enhance GABA inhibition, they have unique properties independent of their ability to induce unconsciousness that alter the long-term effects of early-life exposure (Fig. 1).

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FIGURE 1:
Unlike sevoflurane, early-life propofol does not reduce GABAergic inhibition or reduce social interaction in adult mice.

[SNACC-79] Neurosurgical patient reported experience measures (PREMs) survey in a University Public Hospital

Valero R, Pujol G, Fabregas N, Buisan M, Enseñat J, Gracia I, Leon I. Hospital Clínic de Barcelona. Universitat de Barcelona, Bardelona, Spain

Background: The Catalan Health Care National Department (CatSalut) launches distinct safety phone questionnaires (“PLAENSA program”) every three years to some random selected patients from all public hospitals in order to benchmark PREMs.

Written surveys tend to be the most cost effective and reliable approach. Our aim was to know more precisely the measured experience of our surgical attended patients, using and/or adapting some questions obtained from one specific PLAENSA Survey (patients undergoing hospital admission for any pathology). Selected questions focused with emotional aspects (appropriate care, pain control, and privacy), information (before and after surgery) and overall satisfaction.

Methods: Through an encrypted on-line platform (LimeSurvey®) we created the surveys, sent the e-mails and analyzed the results. Starting on 2019, we continued with the project during 2020 and 2021, the COVID-19 pandemic years. We started sending the surveys to patients operated on the first semester of 2019 and 2021. On 2020, with the COVID-19 pandemic, the scheduled surgery diminished until summer, so we launch the surveys at the end of October. We compared Neurosurgical patients’ responses with overall results.

Results: Answers to the survey are described in Table 1. Main results of some selected questions may be seen in Fig. 1.

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TABLE 1
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FIGURE 1

Conclusions: Patients demand receiving more comprehensive and understandable information and more involvement in several steps of their perioperative journey. We need well-informed patients at the center of the care process. In our opinion, on-line surveys are a good tool to connect with patients and give them a space to explain their opinions, feelings and experiences. In our randomly included populations, patient experiences did not vary during the pre-pandemic year compared to the two years of the pandemic. However, the percentage of responses in 2021 was lower than the previous ones.

Enquestes de Satisfacció CatSalut (Servei Català de la Salut) https://catsalut.gencat.cat/ca/coneix-catsalut/presentacio/instruments-relacio/valoracio-serveis-atencio-salut/enquestes-satisfaccio/.

[SNACC-80] Neurosurgical Patients Perspectives of The Pre-Anesthesia Visit--A Qualitative Analysis

Sharma Deeya, Bentov I, Bentov N. University of Washington, Seattle, Washington, United States

Background: The Pre-anesthesia clinic (PAC) serves to gather medical information to prepare the patients for their procedure, inform the anesthesia team about medical conditions, and identify potentially modifiable factors for optimization before surgery. The PAC is associated with a reduction in unnecessary testing, OR delays, same-day cancelations, and mortality (1). Notably, the PAC is a resource for patients to voice their concerns and have questions addressed. Preoperative evaluation of neurosurgical patients is unique and sometimes different than the general surgical population (2). The aim of this study is to qualitatively analyze patients’ knowledge, expectations, and experience regarding the PAC visit and to compare the perspectives of patients undergoing neurosurgical (cranial and spine) surgery to those of the general elective population.

Methods: The study was conducted at Harborview Medical Center in Seattle, Washington. Following IRB approval, patients were approached immediately before and after their PAC appointment and asked a series of open-ended questions. Demographics (age, gender, and surgical service were recorded. Verbal responses were recorded and transcribed as free text. Free text responses were analyzed by two separate coders using a grounded theory approach, looking for recurrent emerging themes, by first identifying thematically linked words (without a priori identification) and counting the frequency with which responses were linked to the theme. Responses of patients scheduled for neurosurgical and spine surgeries were compared to responses from all other surgical services.

Results: The study population is representative of the clinic population seen annually. The Male/Female ratio of 57%/43% for both the sample size and the clinic population. Neurosurgical patients comprised 23% of the clinic population and 18% of the study population. 127 patients were recruited, 23(18%) Neurosurgical patients and 104 (82%) from other services (orthopedics, ophthalmology, gastroenterology, vascular surgery, urology, and oral and maxillofacial surgery). The average age was not different with 52.6±16.7 years for neurosurgical and 51.1 years ±16.6 for the other services. Females accounted for 30.4% of neurosurgical patients and for 45.2% of the other services. Neurosurgical patients had longer PAC appointments (average of 37±18.84 minutes for neurosurgical patients and 30±18.52 minutes for other patients P=0.05). The five major themes that were identified in the free text are: 1. Questions and Concerns (prepared prior to appointment), 2. Familiarity (past hospital experiences), 3. Difficulties (accessibility to reaching appointment), 4. Confusion (lack of knowledge regarding the purpose of PAC), and 5. Comfort (satisfaction post appointment). Neurosurgical patients have high rates of familiarization with the hospital system due to prior procedures or health conditions and displayed lower rates of confusion regarding the purpose of the PAC. However, neurosurgical patients asked more questions and raised more concerns prior to their appointment. Neurosurgical patients were more likely to have difficulties reaching or accessing their PAC appointment. 100% of the patients in our study stated that all concerns they had or came up with were addressed and left feeling a sense of comfort.

Conclusion: Qualitative analysis of patients’ interviews prior to and after their PAC appointment suggests that neurosurgical patients may utilize more PAC resources but benefit from a PAC visit. Although neurosurgical patients come to have more difficulty reaching PAC and have more questions and concerns, all the patients in our sample indicated a sense of comfort after their visit and stated that all their questions and concerns were addressed (Table 1).

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TABLE 1:
Themes That Emerged in the Qualitative Analysis of Neurosurgical Patient Interviews Prior to and After Their PAC Appointment

[SNACC-81] Noise Pollution in the Neurosurgery Operating Room

Beresian J*, Avitsian R*, Soliman A. Cleveland Clinic, Cleveland, Ohio, United States*. King’s College Hospital NHS Foundation Trust, London, United Kingdom

Background: Noise pollution is an unwanted or undesirable sound in the surrounding environment and is a general stressor in the operating room (1). Several studies have shown the negative effect of the noise on staff performances due to impaired communication, inability to hear monitors and decreased concentration resulting in suboptimal patient care and safety. During neurosurgery and orthopedic surgery, noise level exceeds 95 dBA for most surgery duration. This is above the recommended threshold of 30 dBA set by the World Health Organization. One study showed that one-third of patients consider OR as noisy environment and 16% have felt stressed by these noises. Therefore, noise pollution should be avoided whenever possible out of consideration for both patients and staff. The purpose of this project is to measure noise level in neurosurgery operating rooms in a tertiary academic centre.

Methods: Noise level was measured in 10 neurosurgery operating rooms over 10 days. NIOSH SLM application was used over the Cleveland Clinic provided iPhones. These phones were placed on top of anaesthesia workstation in each operating room for standardization.

Results: The range of Max level was 80.77 dBA to 94.9dBA with a mean of 89.32 dBA. The highest noise level was a peak of 129.2 dBA in a single lumbar laminectomy procedure.

Discussion: The source of noise in the operating room is both from equipment and staff. Equipment related noise like alarms, suction, drills are mostly unavoidable. Staff related noise on the other hand like conversation, laughter and music is controllable. Exposure to noise levels as low as 75dBA may have short and long term effects on health. Noise pollution causes inefficient communication which has been identified as a major root cause of error and poor patient outcome. Of concern, noise might be very distracting during critical periods such as the WHO safety checks and swab counts. Another study shows the reduced mental efficiency and short-term memory disruption among anesthesiology residents exposed to the high operating room noise. Long term effects of noise pollution are hearing loss, increased heart rate and blood pressure (2).

Conclusion: Our study shows that a level of 89.32 dBA is above the recommended level and needs to be addressed. The possibility that the results obtained apply broadly might necessitate an approach at the level of local anesthesiology societies or even at the national level (Fig. 1 and Table 1).

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FIGURE 1:
Schematic illustration of relative intensities of different noise levels with reference to our findings.
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TABLE 1:
Different Procedures and Noise Level Associated. LA eq: Level A-weighted Equivalent Continuous Sound. Max. level: Maximum level. LC peak: peak sound pressure level

References:

1. Fu VX, Oomens P, Merkus N, et al. The Perception and Attitude Toward Noise and Music in the Operating Room: A Systematic Review. J Surg Res. 2021;263:193-206.

2. Katz JD. Noise in the operating room. Anesthesiology. 2014;121(4):894-8.

[SNACC-82] Our experience of using Dexmedetomidine-Propofol sedation in patients undergoing treatment planning Magnetic resonance imaging scan for Deep brain stimulator insertion surgery during Covid 19 pandemic

Srinivasaiah R, Patwardhan P, Vijayendra V. The Walton Centre, Liverpool, United Kingdom

Introduction: Patients undergoing Deep brain stimulator (DBS) insertion require a high-resolution MRI for treatment planning prior to DBS surgery. This group of patients has movement disorders therefore traditionally the planning MRI is done under General anaesthesia to ensure patient immobility and to obtain good quality MRI images. Providing sedation/anaesthesia for MRI procedure during COVID-19 pandemic was challenging. When we restarted elective surgery during Covid-19 pandemic we were worried about aerosol generating procedures, therefore we looked at the feasibility of using Dexmedetomidine-Propofol sedation for treatment planning MRI as an alternative to General anaesthesia to prevent aerosol generating procedure.

Methods: We conducted retrospective review of anaesthetic records of all patients who underwent MRI under sedation for DBS planning from August 2020 to July 2021. We collected the data on patient demographics, Indication & target site for DBS, duration of sedation, complications during the scan, cardiovascular side effects like hypotension and bradycardia during scan, quality of image, duration of PACU stay and post scan complications. The quality of MRI imaging was assessed by the neurosurgeon who did the treatment planning.

Sedation protocol: sedation was commenced with Propofol target controlled infusion (TCI) using Schneider model with effector site concentration (Cet) of 2 to 3 and Dexmedetomidine bolus dose of 1 microgram per kilogram was infused over 10 minutes. All the patients were induced to a Ramsay Sedation Scale of at least 5 or 6. Sedation was maintained with Dexmedetomidine infusion at 0.5 mcg/kg/hr and Propofol TCI (Schneider model Cet of 2 mcg/mL).

Results: During our study period 15 patients underwent MRI under sedation with Propofol-Dexmedetomidine for DBS treatment planning. Of this 7 were males and 8 were females. Age range was from 39 to 75 years. The target site was Subthalamic nucleus in 9 patients, Thalamic nuclei in 4 patients and Globus pallidus internus in 2 patients. Duration of sedation ranged from 40 minutes to 100 minutes with a median of 45 minutes. 2 patients developed movement artefacts during scanning and were converted to GA, 3 patients developed hypotension (20% reduction from pre-induction blood pressure) requiring treatment with ephedrine. Five patients had sinus bradycardia (20% reduction from pre-induction heart rate) but did not require treatment. The qualities of images were classified as good in 11 patients and acceptable in 2 patients by the neurosurgeon involved in treatment planning. None of the patients needed repeat MRI scanning. Patient’s stay in PACU ranged from 20-50 minutes with a mean of 26.5 minutes.

Discussion: Dexmedetomidine-Propofol sedation has been widely used for sedation to perform MRI scans in paediatric patients, its use in adult patients is not well documented in the literature. Propofol enables smooth induction of sedation and rapid recovery however it may cause hypotension, decreased respiratory drive and upper airway obstruction. Dexmedetomidine has been used as a single sedative agent for MRI however its onset of action is slow and when used as a sole sedative agent large dose of dexmedetomidine is required and this may contribute to delayed recovery after sedation.

Propofol-Dexmedetomidine combination has synergistic effects and is advantageous. Propofol can induce sedation smoothly, Dexmedetomidine can reduce dose required for sedation and suppression of motor response in healthy subjects (1). Combination of Dexmedetomidine-Propofol infusion reduced total Propofol dose and decreased the incidence of airway complications in a paediatric study (2).

During our study period 2 patients sedation were converted to General anaesthesia, both patients had raised BMI and had laboured breathing under sedation causing transmitted head movement, therefore patient selection is important for successful scan under sedation. Propofol-Dexmedetomidine sedation can be used safely for treatment planning MRI in selective movement disorder patients.

[SNACC-83] Outcomes After Perioperative Stroke in Patients Undergoing Non-Cardiac Surgery: A Historical Cohort Study

Farmer J*, Flexman A, Sutherland J, Field T, McIsaac D§, Gelb A, Zhou L, Schwarz S, Maclure M, Sun T. The University of British Columbia, St. Paul’s Hospital, Vancouver, British Columbia, Canada**. The University of British Columbia, Vancouver, British Columbia, Canada. The Center for Health Evaluation and Outcomes Sciences, Vancouver, British Columbia, Canada. University of Ottawa, Ottawa, Ontario, Canada§. University of California San Francisco, San Francisco, California, United States. Stanford University, Stanford, California, United States

Study Purpose: Perioperative stroke is a cerebrovascular event occurring after surgery that can result in devastating and often unrecoverable outcomes. Although outcomes of stroke after surgery are generally considered to be worse than stroke in the non-surgical setting, predictors of outcome are poorly characterized for this rare complication. As prognosis is considered when considering therapeutic options, accurate risk assessment is critical in this unique stroke population. Our study aim was to identify predictors of mortality following perioperative stroke in non-cardiac surgical patients. Our secondary aim was to identify predictors of discharge to a non-home facility.

Methods: We included non-cardiac non-neurologic surgical patients who experienced a perioperative stroke in the American College of Surgeons National Surgical Quality Improvement Program database between 2005 and 2020. We extracted data on patient demographics, comorbidities, stroke, and surgical and anesthetic variables. Operation time was used as a surrogate measure of surgical complexity, and severe stroke was defined as requiring either a tracheostomy or craniectomy. Least absolute shrinkage and selection operator (LASSO) technique was used for factor selection to examine variables independently associated with 30-day mortality (primary outcome) and adverse discharge (death or a non-home facility, available after 2010) in multivariable logistic models.

Results: We identified 14,391 patients who experienced a perioperative stroke. Perioperative strokes occurred a median of 5 (interquartile range [IQR]2-12) days after surgery, 25% (N=3,541) of patients died, and 42% (N=4773) were discharged to a non-home facility. Median length of stay was 9 (IQR 4 to 17) days and 17% (N=2478) required intensive care. Independent predictors of 30-day mortality (c-statistic 0.728) included increasing age, anemia, lower body mass index (BMI), postoperative cardiac arrest, myocardial infarction, and renal failure, fewer days from operation to stroke, dependent functional status, history of kidney failure or dialysis and blood transfusion, stroke on the index admission (vs readmission), and general or vascular surgical specialties (Table 1). Similar predictors were identified as predictors of adverse discharge, with the exception of postoperative cardiac complications and the addition of orthopedic surgical specialty.

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TABLE 1:
Independent Predictor Variables Significantly Associated with Increased risk of 30-day Mortality After Perioperative Stroke in Non-Cardiac Surgical Patients (N=14,391) Using LASSO-Penalized Logistic Regression (c-statistic 0.728)

Conclusion: Death and discharge to a non-home facility are common complications following perioperative stroke after non-cardiac surgery. We identified predictors of these poor outcomes, including potentially modifiable risk factors such as anemia, transfusion, and other postoperative complications. Increasing days from surgery to stroke and readmission were associated with improved outcomes, suggesting an interaction between the perioperative period and stroke that warrants further investigation. These findings are novel and warrant further investigation to identify interventions to improve outcomes in this population.

[SNACC-84] Outcomes and Biomarker Response Associated with Ketamine Administration after Traumatic Brain Injury: a Retrospective Study

Khan S*, Peters A. Creighton University School of Medicine, Omaha, Nebraska, United States*. Oregon Health & Science University, Portland, Oregon, United States

Background: Traumatic brain injuries (TBIs) remain a serious public health issue with limited therapeutic options. Historically contraindicated in head injuries, ketamine is increasingly utilized following TBIs despite a lack of efficacy and safety studies.[1]

Methods: A retrospective analysis was performed using data from the TXA for TBI study, a randomized controlled study in which TXA was administered pre-admission in 1g, 2g and placebo doses to patients who sustained TBIs between May 2015 and November 2017 [2]. The primary outcome was mortality within 6 months of TBI; secondary outcomes included morbidity, vital signs responses and TBI biomarker response. Demographic variables and risk factors analyzed included age, sex, BMI, weight, Glasgow Coma Score (GCS), Injury Severity Score (ISS), seizure history, intubation, and TXA dosage group; Glasgow Outcomes Scale Extended (GOSE) and Disability Rating Scale (DRS) assessed morbidity at discharge and 6 months. Statistical analysis consisted of propensity matched logistic regression as well as a repeated measures analysis of biomarkers.

Results: Of 840 patients with ketamine exposure data, 131 patients received ketamine and 709 did not receive ketamine. Patients receiving ketamine had lower GCS (6.7 (mean)±3.2 (SD) to 7.6±3.5), worse ISS (20.7±13.6 to 18.8±13.1), and were more frequently intubated than patients who did not receive ketamine (88.6% to 44.3%), however these differences were not statistically significant. There was no significant difference in mortality (12.2% ketamine exposed vs 15.4% ketamine unexposed; P>0.05) or required surgical intervention (6.9% ketamine exposed vs 11.1% ketamine unexposed; P>0.05). The incidence of cardiac failure (1.5% ketamine exposed vs 0.8% ketamine unexposed) and seizure (3.1% ketamine exposed vs 1.0% ketamine unexposed) were too few to statistically analyze. GOSE and DRS scores were compared between groups at discharge and 6 months post-injury, with no significant differences at either time interval. Discharge GOSE (3.93±2.08 ketamine exposed to 4.31±2.41 ketamine unexposed); 6-month GOSE (5.35±2.43 exposed to 5.40±2.64 unexposed); discharge DRS (9.76±9.70 exposed to 9.29±10.26 unexposed); and 6-month DRS (8.01±11.12 unexposed to 6.82±9.94 exposed). Ketamine exposure was associated with a decreased risk of elevated ICP (50% ketamine exposed vs 82.4% ketamine unexposed; P<0.05). There were no statistically significant differences in blood pressure extremes, heart rate extremes, temperature extremes, or hypoxia between groups. A subgroup analysis of intracranial hemorrhage-positive patients was performed, with no significant differences observed for the GOSE and DRS time intervals. Ketamine exposure was again associated with a decreased risk for elevated ICP in the hemorrhage-positive group, with no significant differences in the remaining vital signs responses measured. Serum biomarker GFAP, MAP-2, and UCHL1 levels compared between the ketamine exposure groups at t=0, 6-, 12-, 24-, and 48-hour intervals revealed no significant differences between groups for MAP-2 and UCHL1. Serum GFAP levels were significantly lower in the ketamine group at t=6, 12-, 24-, and 48-hour intervals compared to the unexposed group (P<0.0001). In the intracranial hemorrhage subgroup, biomarkers levels at identical time intervals indicated statistically significant differences in the ketamine-exposed group for GFAP at t=12, 24-, and 48-hours (P<0.05), and t=6, 12-, 24-, and 48-hours (P<0.05) for MAP-2. No significant differences were seen in UCHL-1 serum levels between groups.

Conclusions: Ketamine administration was not associated with increased mortality or worse recovery after TBI and was associated with fewer instances of elevated ICP. Ketamine exposure was associated with a differential effect on the GFAP biomarker and a significant decrease in MAP-2 concentration in the intracranial hemorrhage positive group (Fig. 1).

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FIGURE 1:
Effect of ketamine on serum human biomarkers post-TBI. Serum biomarker levels for UCHL1, MAP-2, and GFAP were assessed at 0, 12, 24, 36, and 48 hour intervals after admission in the ketamine exposed and ketamine unexposed populations.

[SNACC-85] Perioperative Analgesic Considerations for a Patient on Buprenorphine-Naloxone Undergoing Total Intravenous Anesthesia in a Multilevel Lumbar Fusion

Loucks E, Hariharan D, Yeh C. University of Illinois College of Medicine, Chicago, Illinois

Management of acute pain in the chronic pain patient population can be a challenge, especially in those with refractory opioid use. We present a case focusing on anesthetic care for a chronic pain patient on long term suboxone use, undergoing high risk multilevel spine surgery requiring no muscle relaxation due to neuromonitoring. Our patient was a 69-year-old male with a history of opioid use disorder with severe degenerative joint disease leading to lumbar stenosis and left sided foot drop, scheduled for a two-stage multilevel lumbar spine surgery, anterior lumbar interbody fusion followed by transformational lumbar interbody fusion. His past medical history includes chronic obstructive pulmonary disease with a baseline saturation of 93-96% on room air, hypertension, hepatitis C, post traumatic stress disorder, and multi-substance use with heroin and alcohol. Both stages of the surgery require somatosensory evoked potential (SSEP) and motor evoked potential (MEP) neuromonitoring. At the time of surgery, the patient was taking buprenorphine-naloxone for the management of opioid disorder and was being weaned down in preparation for surgery per his primary care physician. Due to intraoperative neurophysiological monitoring, total intravenous anesthesia (TIVA) with propofol, ketamine and remifentanil was used. Additional analgesic agents including a lidocaine infusion, dexmedetomidine boluses, and a one-time dose of methadone were utilized to achieve analgesic goals. Intraoperatively, hemodynamic fluctuations occurred, and meticulous thought was given to consider all differentials in the setting of TIVA. Hemodynamics can be easily influenced by the titration of TIVA, analgesic requirement, and resuscitation requirement. The surgical blood loss was estimated at two liters, and the patient was extubated at the end. Postoperatively, the patient experienced severe 10/10 on postoperative day one and was evaluated by the chronic pain team. The hospital course involved ketamine titration and restarting suboxone following a loading dose. Anesthetic management in this case posed multiple challenges in providing adequate anesthesia due to the complexity of the patient’s chronic pain in the setting of no muscle relaxation and the ceiling opioid effect from taking suboxone. Furthermore, the patient experienced acute kidney injury post-operatively, most likely caused by acute blood loss despite meeting blood pressure goals due to inadequate analgesia on board. This case demonstrates the need for unique institutional specific guidelines established in managing complex chronic pain patients undergoing spinal surgery in the perioperative period.

In our presentation, we will discuss the perioperative management of chronic pain patients on long term mixed opioid agonist-antagonists and the challenges this provides in the setting of TIVA. We will discuss how intraoperative hemodynamics can be confounded in the setting of TIVA in chronic pain patients. Additionally, we will discuss the challenges in maintaining hemodynamic stability, adequate analgesia, and optimal surgical conditions in this patient population within the scope of neuromonitoring. Finally, we will review the management of multimodal analgesia utilized perioperatively for this patient.

[SNACC-86] Perioperative Complications During Posterior Fossa Surgery in Sitting Position: A Single-Center Retrospective Study

Rath G, Balakrishnan A, Bindra A. All India Institute of Medical Sciences (AIIMS), New Delhi, India

Background: The sitting position was a favored position for surgery on the posterior fossa. Its use has declined due to the increased incidence of life-threatening complications. Our center continues to practice this neurosurgical position, although less frequently. Hence, a study was conducted to determine the incidence of perioperative complications with sitting craniotomy.

Methods: Medical records of 206 patients who underwent posterior fossa surgery in a sitting position over 10 years were analyzed. Data on demographics, perioperative complications, and postoperative neurological status were recorded. Statistical analysis was done by Chi-square and Wilcoxon rank-sum test, and a P-value <0.05 was considered significant.

Results: Out of 206 eligible patients, 188 patients had near-complete data. A declining trend was observed on the practice of sitting position during the study period. None of the patients was complicated with quadriparesis, macroglossia, or peripheral nerve injury. One patient developed tension pneumocephalus. Thirty-nine patients presented with episodes of venous air embolism (VAE) with an incidence of 20.7%. No correlation was found between cerebrospinal fluid (CSF) drainage procedures or previous craniotomy and the development of VAE. Intraoperative brainstem handling was the most common reason (72%) for postoperative mechanical ventilation. At the time of discharge, 166(88.3%) patients had good neurological outcomes, while poor outcomes were seen in 4 and mortality in 15(7.9%), respectively.

Conclusions: The overall incidence of perioperative complications with the sitting position was not high enough to prevent its routine use. Moreover, the development of VAE was not associated with an increased risk of complications or patient mortality. Therefore, while debatable, the use of sitting craniotomy continues to be safe in expert hands.

[SNACC-87] Perioperative Stroke Following Implantation of Left Ventricular Assist Device

Yen P*, Sun T, Besola L, Cheung A, Peng D§, Chiu W, Bashir J, Johnston D, Field T, Flexman A. UBC Anesthesiology, Vancouver, British Columbia, Canada*. Providence Health Care, Vancouver, British Columbia, Canada. UBC Cardiac Surgery, Vancouver, British Columbia, Canada. UBC Centre for Cardiovascular Innovation, Vancouver, British Columbia, Canada§. Vancouver Stroke Program, Vancouver, British Columbia, Canada

Background: Perioperative strokes (ischemic or hemorrhagic) occur during surgery or within 30 days of surgery [1]. They may be symptomatic or asymptomatic, and are commonly embolic but may result from a variety of etiologies. They frequently lead to significant morbidity and mortality [2]. Perioperative strokes are more common after cardiac surgical procedures, particularly left ventricular assist device (LVAD) implantation, with reported rates of 10-30% within 2 years (approximately 4% within the first month, 9% within the first 6 months, and 14% within the first year) [3]. Our primary objective is to characterize the post-LVAD implantation perioperative stroke population, a cohort not yet well studied.

Methods: We conducted a single-centre, retrospective case series of patients who experienced a perioperative stroke following implantation of either the HeartMate III (Abbott) or HeartWare HVAD (Medtronic) as a bridge to transplant, transplant candidacy, transplant decision, or recovery, between January 1, 2008 and August 31, 2021. We extracted data on patient demographics, comorbidities, risk factors for perioperative stroke, stroke characteristics and timing, as well as relevant interventions. We noted patient outcomes such as survival to discharge and cardiac transplant, as well as functional recovery. Descriptive statistics were used to present the data.

Results: We identified 198 patients who underwent LVAD insertion during the study period; 23 of them (11.6%) experienced an imaging-proven stroke within 30 days, and were included in the study. The median age of these 23 patients was 57 (IQR 50-63.5) years, and 82.6% (19/23) had at least one established risk factor for perioperative stroke. Specifically: 21.7% (5/23) had had a previous stroke or TIA; 4.3% (1/23) had known carotid stenosis; 43.5% (10/23) had a smoking history; 39.1% (9/23) had pre-existing atrial fibrillation; 69.6% (16/23) had documented postoperative atrial fibrillation; and at least 56.5% (13/23) had a subtherapeutic INR at the time of the stroke. Though most patients had been started on warfarin, few were concurrently bridged with IV heparin (per institutional practice). The vast majority of strokes (17/23, 73.9%) occurred in the first 7 days postoperatively. 82.6% (19/23) of strokes were primary ischemic, 13% (3/23) were primary hemorrhagic, and one patient (4.3%) experienced simultaneous ischemic and hemorrhagic insults. All ischemic strokes were presumably embolic in nature, with multiple potential contributing factors, such as the LVAD device itself, atrial fibrillation, and pre-existing left ventricular clot. Timing of onset for 69.6% (16/23) of strokes was unclear, and 65.2% (15/23) of patients were intubated, sedated, or recently extubated at the time of onset, which contributed to delayed recognition and diagnosis. None of the patients underwent endovascular thrombectomy (EVT) due to lack of proximal clot, uncertain timing of onset, established infarcts, poor prognosis, or another contraindication. Two patients were started on therapeutic anticoagulation via intravenous heparin infusion, and the rest were given supportive management or palliated. Outcomes were generally poor with 52.2% (12/23) of patients dying with the LVAD in situ, 10 of whom did not survive the index admission. One-third (8/23) of patients survived to transplant, and 13% (3/23) were eventually explanted.

Conclusions: Our study provides a detailed look at an increasingly common and high-risk population: those with LVAD implantation experiencing stroke in the perioperative period. The majority of these strokes were ischemic and associated with a subtherapeutic INR. Our results suggest that this cohort frequently experiences delays to diagnosis of stroke, low rates of therapeutic intervention, and poor outcomes. Thus, individuals undergoing LVAD implantation may benefit in the perioperative period from more frequent routine neurologic assessment, possibly with routine imaging, alongside careful management of anticoagulation.

[SNACC-88] Pilot Study of Post-Anesthesia Care Unit Delirium at Columbia University Medical Center

Daramola A*, Yasin B, Cassim T, Isik O*, Garcia P. Columbia Vagelos College of Physicians and Surgeons, New York, New York, United States*. Columbia University, New York, New York, United States

Introduction: Delirium is an acute disorder of attention and cognition that typically affects older adults. Besides age, additional risk factors have been identified as predisposing individuals to develop delirium: stroke, cognitive impairment, depression, functional impairment, severe illness, and previous delirium.1-4 Perioperative neurocognitive disorders like delirium can develop acutely after emergence from general anesthesia.5 Studies have shown that patients who develop delirium post-operatively have increased morbidity and mortality; and may be at-risk for developing longer term cognitive and functional impairments.6-8 Less is known about the significance of “early” postoperative delirium that develops in the post-anesthesia care unit (PACU). Recent literature suggests that PACU delirium may be associated with increased risk of subsequent postoperative delirium as well as negative outcomes such as, re-admission to the hospital.4 Previous studies have found the incidence of PACU delirium to range from 16-45%.9.

Methods: Our sample consisted of adult patients admitted to the PACU between December 2021 and February 2022 after undergoing general anesthesia for surgery. This study began as a quality improvement project with IRB exemption. As we now intend to publish our results to an extramural audience, an IRB waiver is pending. Each patient was administered two brief cognitive assessments, validated as screening tools for delirium. Both the confusion assessment method for the intensive care unit (CAM-ICU) and the three-minute diagnostic interview for the confusion assessment method (3D-CAM), where administered in sequence at least 15 minutes after arrival in the PACU. Additional data was gathered via retrospective chart review.

Results: A total of 100 adult patients who underwent anesthesia were included in our analyses. Twenty-eight out of 100 patients screened positive for delirium in the PACU by either measure. There were 16/28 patients who screened positive for delirium on both the CAM-ICU and the 3D-CAM. The average age of our sample was 54 years old, with a standard deviation of 18 and median age of 59 years old. We failed to find an association between age and a positive screen for PACU delirium (P=0.59).

Discussion: Although known to be associated with longer hospitalizations and increased risk of re-admission, PACU delirium is a relatively new concept that anesthesiologists may overlook its clinical significance. Although our analyses demonstrated an incidence of PACU delirium consistent with other studies, we failed to find an age association with PACU delirium in our population. This may be due to a failure of our sample to represent the entire age spectrum more completely. The observational nature of our study should be considered a limitation as a proper investigation of the age effects would require enrollment of an equal number of patients per “age decade”. Interestingly there was an incomplete overlap of CAM-ICU and 3D-CAM in identifying delirium in our population. Different sensitivities of the CAM-ICU and 3D-CAM screening tests in identifying delirium in both the PACU and hospitalized patients has been previously reported.10,11 Our study confirms that these measures may be attuned at picking up different aspects of delirium (Fig. 1).

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FIGURE 1

[SNACC-89] Postoperative Morbidity Survey and Length of Stay in Patients Following Endovascular Thrombectomy

Bapat S*, Wan Zakaria W, Bhat R, Raja M§, Shivananda G. National Hospital for Neurology and Neurosurgery, London, United Kingdom*. University Malaya, Wilayah Persekutuan, Kuala Lumpur, Malaysia. Kasturba Medical College, Karnataka, India. Royal Free Hospital NHS Foundation Trust, London, United Kingdom§

Background: Stroke is a leading cause of death and disability worldwide and is associated with a substantial socioeconomic burden. Acute ischaemic stroke (AIS) accounts for 85% of all strokes; 10 -20% of these are the result of large vessel occlusion (LVO). Endovascular thrombectomy (EVT) is now gold standard treatment for this cohort of patients who meet criteria. Currently, there is a lack of data concerning morbidity sustained by non-neurological organ systems in patients with AIS who undergo EVT. The Post Operative Morbidity Survey (POMS) is a simple method of identifying and measuring postoperative complications that could delay discharge from hospital using clinical features in nine organ domains at chosen time points.

Aim: We used the POMS to determine the prevalence of early morbidity after EVT and its impact on hospital length of stay (LOS).

Methods: All patients with a full data set undergoing EVT at our institution between 1st January 2019 and December 2020 were included in this retrospective observational study. Data were gathered from electronic health records and the Sentinel Stroke National Audit Programme (SSNAP) database; demographics, ASA-PS, modified Treatment in Cerebral Infarction (mTICI) score, morbidity as defined by POMS on days (D) 1, 3, 8 and 15, median LOS and thirty-day mortality. We compared LOS in patients who were POMS positive i.e., had one or more POMS morbidity items present during their hospital admission, and those who did not (POMS negative).

Results: Ninety-one patients were included; 53.8% were female, median age was 72.0 years (IQR 57-83), 70.3% were ASA-PS class 3 and 4. Anterior circulation LVO was present in 92.3% and EVT was carried out under general anaesthesia in 75.8% of patients. Overall median LOS was 7.0 days (IQR 4-13). At least one or more POMS domains were present in 91.2% of patients during their admission (Table 1), who had a median LOS of 7.0 days (IQR 4-13). For those who encountered no morbidity i.e., were POMS negative in the postoperative period, median LOS was 5.5 days (IQR 4-15.5). A postprocedural mTICI score above 2b was obtained in 90.1% of patients. Mortality for all patients at thirty-days was 16.0%; of those remaining, 40.7%, 28. 6% and 16.6% were discharged to their local hospital, home or a rehabilitation facility respectively.

T14
TABLE 1:
Prevalence of Overall Morbidity and Morbidity by Postoperative Morbidity Survey Domains on Days 1, 3, 5, 8, and 15 Following Endovascular Thrombectomy

Conclusion: Prevalence of early morbidity as defined by POMS in patients undergoing EVT for LVO is high, but not unexpected. The most common causes of morbidity overall were renal, followed by gastrointestinal, almost all related to the presence of a urinary catheter and nasogastric tube respectively. However, morbidity and thereby LOS related to these POMS organ domains may be overestimated. Patients in this group are more likely to require continued urethral catheterisation and nasogastric tube placement as a result of AIS. Pulmonary complications were the next most prevalent source of overall morbidity and indicates that a significant proportion of patients were receiving supplementary oxygen or required respiratory support, predominantly up to 72 hours postoperatively. Overall, LOS, rates of successful reperfusion, and discharge destination were comparable to those reported. Our findings suggest that the POMS alone may not be specific enough to determine prevalence of morbidity and impact on LOS in this cohort. There are numerous factors reported in literature influencing outcome following EVT including National Institute of Health Stroke Scale (NIHSS) and ASPECTS scores as well as glycaemic control. Developing a tool incorporating these items with POMS domains, may be more useful to quantify postoperative morbidity and target intervention in order to improve LOS following EVT.

[SNACC-90] Predictive model for intraoperative blood loss in scoliosis surgery: A multi-variate regression analysis of confounding risk factors from a cohort of 109 patients

MB S, Ranganathan P, Garg B, Khanna P. AIIMS, New Delhi, India

Study design: A retrospective cohort study.

Objective: Scoliosis surgery is often sought with massive blood loss owing to muscle dissection, multiple osteotomies, and instrumentation . Many blood conservation techniques in the last two decades have been recommended to reduce blood loss and subsequent related transfusion. However, an ability to predict patients and relative risk factors could help the surgical team to anticipate the challenges ahead. The primary aim of the study is to analyze the various compounding risk factors and their co-relation to blood loss through univariate analysis. Secondly, through a multivariate regression analysis of significant compounding factors; we aim to derive a pre-operative ‘model’ to predict the anticipated blood loss.

Methodology: We analyzed a cohort sample of 109 patients who were operated on in single-stage, all posterior approach by the same surgeon between July 1, 2012, and July 1, 2021. Hospital records of patients were retrieved from a prospectively maintained database, which included demographic, curve parameters, peri-operative events, and complications. All descriptive statistics were reported as mean values+/−standard deviation. Univariate analysis was conducted to investigate the correlation of various risk factors to blood loss which included – age, sex, cobbs angle, flexibility index, thoracic kyphosis, operative duration, number of levels fused, Schwab’s osteotomy grade, rib resection, extension to pelvis and blood parameters – hemogram, platelets, albumin. Any independent variable that reported statistical significance with P<0.05 were included in the multi-variate regression model study . Following a linearity test, a multiple regression was applied to derive a regression equation with statistically significant risk factors.

Results: The study cohort involved 109 patients with a mean age distribution of 16.13 +/−3.81 years (range -11- 20 y) and included 78 females (71.6%) and 31 males (28.4%) with a mean BMI – 20.15 kg/m2 . The majority of the curve in the cohort included Lenke 1 (66/109), Lenke 3 (18/109), and Lenke 5 (16/109) respectively. The pre-operative parameters of the curve included – Cobb’s angle -67.77+/−16.94 (range – 52 – 94) with a flexibility index of 21.87+/−13.87 degrees. Perioperatively, the average levels fused in the deformity correction included -11.92+/−2.15 (range 5- 14) with mean instrumented screws - 17.62+/−3.42 (range 9 – 22). In 7/109 subjects, the distal extension of instrumentation extended to the pelvis. The mean duration of surgery was 234.93±79.66 minutes. The majority of patients underwent Schwab’s osteotomy 1, 2, and 3 (>95%) with rib resection in 11 patients. The average blood loss in the cohort was 751.1 +/−429.6 mL (range 450 - 1250 mL-) with a need of 1.59+/−1.16 units (range) blood transfusion required during the perioperative period. There was a significant deformity correction with post-operative Cobbs -25.98+/-12.22 (63% correction). On univariate analysis , independent risk factors to increased blood loss were increased cobbs angle (Co –relation -0.2553, P<0.0074), Levels fused >7 (co- relation 0.2490, P<0.0090) ,operative duration (co-relation 0.2013, P<0.0358) and rib resection (1020.975+/-94.641, P<0.001). On multivariate regression of these independent risk factors – rib resction was the single most statistically significant parameter. A prediction model was derived to anticipate blood loss during deformity correction – 197 +3.52 (Cobbs angle) + 18.42(Number of levels fused) + 981 (rib resected; No-0, Yes-1) (Predicted model –F(3,109) 44.46, Adjusted R2 =0.54, P<0.05).

Conclusion: Increased Cobb’s angle, the number of levels fused and rib resection predicted a massive blood loss, which warranted blood transfusion and resulted in subsequent morbidity. Henceforth, these predictive factors should alarm the surgical team to anticipate increased blood loss.

[SNACC-91] Predictors of intensive care unit admission in pediatric scoliosis surgery: an outcome analysis study of risk factors in 81 patients

MB S, Kumar A, Garg B, Khanna P. AIIMS, New Delhi, India

Study design: Retrospective cross-sectional study.

Objectives: While experiencing the current health care scenario in the pandemic, it’s necessary to move to adopt evidence-based practices aimed at judicious use of resources without compromising the quality of care in scoliosis surgery. The aim of the study is to analyze the predictors for ICU (intensive care unit) admission of patients operated on for pediatric spine deformity. Secondly, to investigate the risk factors associated with intensive care admission for posterior spinal fusion using univariate and multivariate analysis.

Methods: A single institutional, longitudinally maintained database was used to retrospectively collect the data of all 81 patients who met our inclusion and exclusion criteria. All patients underwent posterior spinal fusion only, using a standardized anesthesia and pain management technique. Muscle relaxant was avoided during the procedure and anesthesia was maintained on intravenous infusion of opioids, and propofol. We analyzed preoperative factors (demographic parameters, etiology, preoperative PFT, and Cobb’s angle) and intraoperative factors (number of spinal segments fused, osteotomy, blood loss, and temperature‘) influencing the ventilation and intensive care admission. Univariate and multivariate analyses were performed to identify factors associated with ICU admission. Significance was set at P<0.05.

Results: The mean age of the cohort was 14.8+/−2.5 years with males (32, 40%) and females (49, 60%). The deformity etiology varied in cohorts with congenital (48%), idiopathic (36%), syndromic (10%), and neuromuscular (6%) respectively. The mean Cobbs angle was 63.7 +/-15.1 degree with mean fused segments -9.3+/-3.1 vertebra. 31 patients of the cohort required ICU stay with a mean average of 2+/−0.8 days. Out of thirty-one patients, fifteen patients (48%) were not extubated after surgery and were sent to ICU for postoperative mechanical ventilation. The average duration for mechanical ventilation for these patients was 7.1±39.4 hours whereas; the average intra-operative duration was 5.5±1.6 hours. Univariate analysis demonstrated pre-operative factors - Cobbs angle >60, FEV1 <60, FVC <60 and intraoperative factors – hypotension, hypothermia, blood loss were statistically significant parameters influencing ICU admission. Seventeen patients (20%) were operated for the neuromuscular and syndromic cause of scoliosis, of which 06 patients (35%) required ICU postoperatively (P=0.77). Multivariate analysis revealed pre operative factor –degree of curve (Cobb’s angle, (OR 6.09 P=0.02 CI 95%- 1.27-29.06), intra operative parameters (hypotension, (OR 4.2 P=0.2 CI-1.23-14.83), (0.021), hypothermia, (OR 10.79 P=0.01 CI-1.64-70.94), and duration of surgery (OR 4.17 P=0.06 CI=0.9-19.32) were independent risk factors influencing ICU admission. For postoperative pain control, in all patients, local anesthetic was infiltrated at the surgical site, and in some patients (11%) intrathecal morphine was given whereas, in others, intravenous fentanyl infusion was used. All patients have satisfactory pain control post-operatively.

Conclusion: Physiological parameters including - hypothermia, intraoperative hypotension, and reducing operative duration in deformity correction surgeries can directly reduce the incidence of ICU stay and further lead to better resource utilization, especially during this pandemic scenario. Hypothermia has strongest association with ICU stay, which is potentially a modifiable and controllable variable.

[SNACC-92] Prehospital Administration of Tranexamic Acid to Traumatic Brain Injury Patients: A Systematic Review

Theresia S, Anakotta V, Firdau R, Tantri A, Theresia S, Anakotta V. Universitas Indonesia, Jakarta, Indonesia

Background: Traumatic brain injury (TBI) is a significant cause of mortality and morbidity worldwide, especially in children and young adults, and causes a high socioeconomic burden, leading to high medical costs and lost productivity. In order to reduce the undesirable outcome of TBI, efforts to develop TBI treatments have been made. TBI is usually accompanied by intracranial hemorrhage occurring in 25% to 45%, 3% to 12%, and 0.2% of severe, moderate, and mild TBI cases. This bleeding usually causes the prognosis for TBI to be poor; following TBI, a state of hyperfibrinolysis peaks within 3 hours, leading to hematoma expansion.

Objective: This systematic review will discuss the effects of immediate prehospital administration of tranexamic acid (TXA) in patients with traumatic brain injury.

Methods: A systematic literature search was conducted in PubMed, Cochrane, and EMBASE to evaluate all articles that discussed the use of TXA in TBI in the fields of prehospital administration.

Results: 51 publications were identified using the search criteria defined above. After examining titles and abstracts and excluding duplicates, a total of 3 articles were selected for analysis. In the CRASH-3 study, it was found that in patients admitted within 3 hours of injury, the risk of death related to head injury was 18.5% in the tranexamic acid group compared to 19.8% in the placebo group (RR 0.94.95%) CI 0.86 to 1.02). The risk of head injury-related death was reduced with tranexamic acid in patients with mild to a moderate head injury (RR 0.78. 95% CI 0.64-0.95) but not in patients with severe head injury (RR 0.99.95% CI 0.91–1·07; P=0.030). This study reported that early treatment was more effective than delayed treatment in patients with mild and moderate head injury (P=0.005). However, the timing of treatment had no clear effect in patients with severe head injury (P=0.73).

A study conducted by Rowell et al found that the primary outcome occurred in 65% of patients in the tranexamic acid group vs 62% in the placebo group (difference, 3.5%; [90% one-sided confidence limit for benefit, 0.9%]; P=0.16; [97.5% 1-side confidence limit for hazard, 10.2%]; P=0.84). Then for the secondary outcomes, there were no statistically significant differences in 28-day mortality, 6-month Disability Rating Scale scores, and progression of intracranial hemorrhage. Then in the study of Jokar et al, it was found that although a CT scan of the brain showed a significant increase in bleeding volume in both groups after 48 hours, this result was significantly less in the tranexamic acid group than in the placebo group (P=0.04). The mean total bleeding expansion was (1.7±9.7) mL and (4.3±12.9) mL in the TXA and placebo groups, respectively (P<0.001).

Conclusion: Prehospital administration of TXA had a good effect compared to the placebo group in blood volume, but there were no significant differences between the studies conducted for severe TBI and secondary outcomes.

[SNACC-93] Preoperative Consideration of Pulmonary Embolism Risk in Staged T2-S1 Fusion

Vetter O, Kim E. University of Illinois at Chicago, Chicago, Illinois, United States

Introduction: Surgery places patients at a unique risk for thromboembolic events. Elements such as acute inflammatory reaction to tissue trauma, activation of the clotting cascade, and venous stasis during the perioperative period play a role in conferring this risk. Specifically, spinal surgery can further increase this risk due to prolonged perioperative immobilization, complex or multi-level and prolonged procedures, and advanced age. Risk factors unique to the patient include obesity, immobility, cancer, and history of thromboembolic events. We present a case of intraoperative pulmonary embolism (PE) in a high-risk patient during the final stage of a multilevel spinal fusion in order to highlight the importance of preoperative optimization in these patients.

Case: The patient is a 57yoM, BMI 39 with PMHx of HTN, DM, and chronic low back pain presenting for T2-S1 fusion. After a surgery the year prior, the patient suffered a provoked DVT and submassive PE requiring catheter-directed thrombolysis; he subsequently completed 3 months of anticoagulation. Originally, the procedure was to be performed in 2 stages, but given almost 4 liters of blood loss with initial exposure the decision was made to perform the procedure in 3 stages. Both stages 1 and 2 required significant blood product transfusions and vasopressors, though hypotension was never sustained. Hourly arterial blood gases (ABGs), a cell salvage device, reliable large bore IV access, rigorous blood pressure control, colloid administration, and EV1000-guided fluid management were utilized to recognize and treat hypovolemia, anemia, and hypotension. Additionally, measures were taken in light of his history of provoked DVT - SCDs were applied, TXA was avoided despite propensity for blood loss, and normothermia was maintained. Following the 1st stage, the patient developed significant lower extremity weakness that severely limited his mobilization. Echocardiogram was obtained due to concern for new onset atrial fibrillation, which was normal. Prophylactic subcutaneous heparin was continued between the 2nd and 3rd stages. Prior to the third stage procedure, venous dopplers were ordered but never completed. Despite these steps, during the 3rd and final stage 14 days later, the patient’s intraoperative course was complicated by suspicion of intraoperative pulmonary embolism. This presented as a growing and persistent large gap between end tidal CO2 and PaCO2. CT PE immediately postoperatively demonstrated a left main pulmonary artery PE that almost completely occluded the main pulmonary artery bifurcation. An IVC filter was placed and the patient was placed on a heparin infusion once the neurosurgical team felt that the benefits of anticoagulation outweighed the risk of postoperative bleeding.

Discussion: Our case highlights the importance of preoperative evaluation and management of patients at elevated risk for thromboembolic events. When optimizing patients who are at high risk of intraoperative pulmonary embolism, one must consider patient- and procedure-specific risk factors. Our patient demonstrates several significant risk factors that are not uncommon in spine surgery patients, including obesity, history of DVT, complex and protracted operative course, and prolonged immobility. Once his mobility became further limited following the 1st stage, the effects of this on his already heightened thromboembolic risk must be recognized during preoperative evaluation. A discussion between the anesthesiology and neurosurgery teams voicing concern over the duration of time that passed between the 2nd and 3rd case could have prompted a push for the venous dopplers to be completed, and the consideration of an IVC filter placement prior to his final stage. A balance must be struck between the possibility of bleeding in major spine surgery and the danger of the hypercoagulable state that accompanies prolonged immobilization in an already high-risk patient.

[SNACC-94] Preoperative Eyes-Open and Eyes-Closed Electroencephalography (EEG) Features as a Possible Predictor of Postoperative Delirium Vulnerability

Acker L, Wong M, Au S, Roberts K, Giattino C, Moretti E, Devinney M, Reese M, Whitson H, Woldorff M, Berger M. Duke University, Durham, North Carolina, United States

Postoperative delirium (POD) is a syndrome of acute, fluctuating changes in attention and consciousness that affects 15-50% of older surgery patients and is associated with increased risk of mortality, lost independence, and increased incidence and progression of dementia. While much attention has been given to intraoperative electroencephalography (EEG) and the risk of POD, investigations of preoperative EEG and its relationship to POD is relatively unexplored. This study retrospectively analyzed pre-operative, 32-channel whole head EEG data from 66 subjects (n=13 with delirium) age ≥60. This cohort is a subset of patients from INTUIT, an IRB-approved, single-center prospective observational study of older adults undergoing non-cardiac, non-neurological surgery (Berger et al, 2019). This subset of INTUIT subjects underwent preoperative, awake, resting, eyes-closed and eyes-open EEG recordings. Subjects were evaluated for POD with 3-minute delirium assessment method (3DCAM) evaluations twice daily until postoperative day 5 or hospital discharge. Spectral EEG power as a function of topographic region (eg, occipital, parietal, frontal) was evaluated among the POD and non-POD groups. On-going preliminary analysis suggests that there may be differences between the POD and non-POD groups in eyes-closed beta (13-20 Hz) and theta (4-8 Hz) spectral bands, particularly in the occipital topographic region.Ultimately, we expect that the results of this study will inform future work about spectral pre-operative EEG features as potential predictors of POD risk in older adults.

[SNACC-95] Preoperative Sleep Apnea and Blood-Brain Barrier Breakdown

Devinney M*, Spector A*, Wright M*, Thomas J*, Avasarala P*, Acker L*, Veasey S, Marcantonio E, Terrando N*, Whitson H*, Mathew J*, Berger M*. Duke University, Durham, North Carolina, United States*. University of Pennsylvania, Philadelphia, Pennsylvania, United States. Harvard Medical School, Boston, Massachusetts, United States

Introduction: The blood-brain barrier (BBB) is a selective barrier that regulates the influx of peripheral inflammatory mediators, toxins, and other large molecules into the central nervous system (CNS) to support its normal function. Indeed, cognitive dysfunction results from BBB breakdown in various neurocognitive disorders including Alzheimer’s disease dementia, vascular dementia, traumatic brain injury and potentially postoperative delirium. One way to prevent these disorders is to reduce BBB breakdown, but we unfortunately lack clinical interventions to restore normal BBB function. One potential modifiable risk factor for BBB breakdown is sleep apnea, because sleep apnea animal models exhibit reversible BBB breakdown. However, BBB breakdown has not been evaluated in older sleep apnea patients because it is difficult to directly measure BBB permeability. BBB permeability can be assessed by measuring the CSF-to-serum ratio of albumin (Qalbumin), which is the gold standard CSF biomarker of BBB breakdown. Here, we measured preoperative Qalbumin (i.e., BBB breakdown) in a cohort of 101 non-cardiac surgical patients that underwent home sleep apnea testing, to determine the relationship of untreated sleep apnea with BBB breakdown.

Methods: In the Sleep Apnea, Neuroinflammation, & cognitive Dysfunction Manifesting After Non-cardiac surgery (SANDMAN) sub-study of the IRB-approved INTUIT (NCT03273335) study, 101 non-cardiac, non-neurologic surgery patients age ≥60 underwent preoperative home sleep apnea testing (HSAT), and pre- and postoperative cerebrospinal fluid (CSF) and blood sampling. Patients receiving treatment for sleep apnea up to 3 months prior to surgery were excluded. Home sleep apnea testing was performed preoperatively with the type III device ApneaLink Air that includes oximetry, respiratory airflow, snoring, and respiratory effort measurements to quantify the apnea-hypopnea index (AHI), the main measure of sleep apnea severity. Based on these recordings, a board-certified sleep medicine physician diagnosed sleep apnea and determined its severity. CSF and plasma albumin levels were measured with immuno-turbidimetry and bromocresol purple dye-binding, respectively, at baseline and 24 hours postoperatively. Qalbumin was calculated using the formula [cerebrospinal fluid albumin (mg/dL)×1,000]/[serum albumin (mg/dL)]. Univariable and multivariable regression analyses were used to assess the relationship between sleep apnea diagnosis category or AHI with preoperative Qalbumin. Due to a non-normal distribution, preoperative Qalbumin values were logarithmically transformed prior to analysis.

Results: A total of 84 patients had complete preoperative Qalbumin and home sleep apnea testing data. Of those patients, 33 (39.2%) had mild sleep apnea (AHI 5-15), 12 (14.2%) had moderate sleep apnea (AHI 15-30), and 7 (8.3%) had severe sleep apnea (AHI≥30, Table 1). Univariate linear regression demonstrated no significant association of AHI with preoperative Qalbumin (Fig. 1A; β=0.003, 95% CI -0.004-0.010, P=0.403). Multivariable linear regression analysis adjusted for age and sex also showed no significant association of AHI with preoperative Qalbumin (β=0.00, 95% CI -0.01-0.01, P=0.889). No significant association between sleep apnea severity diagnosis category and preoperative Qalbumin (Fig. 1B, severe vs no sleep apnea, β=−0.04, 95% CI -0.41-0.32, P=0.811) was found with univariable linear regression. After adjusting for age and gender, multivariable linear regression analysis showed no significant relationship between sleep apnea diagnosis category and Qalbumin (severe vs. no sleep apnea, β=−0.11, 95% CI −0.27-0.50, P=0.557).

T15
TABLE 1
F49
FIGURE 1:
Relationship of apnea-hypopnea index (AHI) with preoperative Qalbumin values (A) and boxplots of preoperative Qalbumin values by sleep apnea severity diagnosis category (B). There was no significant relationship of AHI or sleep apnea severity diagnosis category with preoperative Qalbumin in univariate or multivariate regression analyses adjusted for age and gender.

Conclusion: We found no evidence of increased BBB breakdown in older surgical patients with untreated sleep apnea. Our next steps are to adjust for additional covariates in our model, including comorbidities (such as diabetes mellitus, vascular disease, and hypertension) that could contribute to BBB breakdown. Our further analyses will also assess whether sleep apnea interacts with comorbidities or age to increase BBB breakdown, and whether sleep apnea predisposes to postoperative BBB breakdown (i.e., evoked by anesthesia/surgery). Overall, our results suggest that sleep apnea is not a major contributor to preoperative BBB breakdown in older adults and that preoperative BBB breakdown is unlikely to be a mechanism that increases delirium risk in sleep apnea patients. Future investigations of blood-brain barrier breakdown are warranted in larger cohorts that includes a greater number of severe sleep apnea patients.

[SNACC-96] Racial disparities in treatment for and outcomes of ischemic stroke at a Code Stroke center

Kang M, Wang M. University of North Carolina, Chapel Hill, North Carolina, United States

Introduction: There is increasing awareness of the importance of social determinants of health (SDH), defined as “the wider set of forces and systems shaping the conditions of daily life,” in determining health outcomes.1 In the United States race continues to be a significant determinant of these factors. In light of the mounting evidence of the significance of racial disparities in access to health care and outcomes, the American Stroke Association (ASA) issued a strong appeal for efforts to address SDH to reduce racial disparities in stroke outcomes.2 The rates of mechanical thrombectomy were examined in an analysis of discharge data from the National Inpatient Sample from 2006-2016 of 1.3 million patients who initially presented with ischemic stroke.3 The rate of treatment for white patients was 0.04% in 2006 increasing to 2.12% in 2016 whereas the rates for African-American patients were lower starting at 0.03% in 2006 and increasing to 1.68% in 2016. African-American race is often considered to be a marker of lower income so the authors performed a multivariable logistic regression adjusting for race, income, primary payer, and other potential confounders and found that race was still an independent predictor of less frequent use of EVT as well as poor outcome. Our institution implemented a Code Stroke protocol in 2015. In this analysis we seek to determine whether there is evidence of racial disparities in time to treatment, rates of treatment, and outcomes of patients with acute ischemic stroke at our institution.

Methodology: This is a cross-sectional analysis of all adult patients who presented to our institution or to an outside hospital and were transferred to our institution with a diagnosis of acute ischemic stroke from 2015 to 2021 (N=2922). The dataset included demographic variables of age, sex, and race. Race was recorded as white, black, Asian, Hispanic, or Other (mostly Native American). Other data collected included time from last known normal neurologic status to presentation in the ED, NIHSS on presentation, whether or not the patient underwent mechanical thrombectomy, disposition, and length of hospital stay.

Statistical analysis was performed using Kruskal-Wallis rank sum test for continuous variables, Fisher’s exact test for dichotomous variables, and Pearson’s chi-squared test for categorical variables.

Results: There was no difference in time from last known normal neurologic status to presentation to the ED although there was a trend toward longer times in the African-American and Hispanic groups compared to the White group.

Average NIHSS scores on presentation were 10 in the African-American group and 12.6 in the Native American group as compared to 8.5 in the White group, 8.3 in the Hispanic group, and 6.5 for Asians (P<0.001).

There was no difference in the rates of patients undergoing mechanical thrombectomy between the groups (P=0.5). All racial groups had longer length of hospitalization as compared to Whites (P<0.001). However, differences in outcomes as reflected by death versus discharge to a skilled nursing facility versus discharge to home were not statistically significant between racial groups.

Conclusion: For patients presenting with acute ischemic stroke at our institution, there was a trend toward longer times from last known normal neurologic status to presentation in the African-American and Hispanic groups as compared to the other groups. Average NIHSS scores were higher for African-Americans and Native Americans as compared to the other groups. There was no statistically significant difference in rates of patients in the groups undergoing mechanical thrombectomy or in outcome data as reflected by discharge disposition. All racial groups had longer length of hospitalization as compared to Whites (P<0.001).

[SNACC-97] Rate of multidrug resistance to antimicrobial drugs in pediatric neurointensive care patients

Prabhakar H, Patel S, Kapoor I. All India Institute of Medical Sciences, New Delhi, India

Background: Multidrug resistant [MDR] microbes in ICU are a global problem. Pediatric neurointensive care patients are vulnerable to MDR infections due to underdeveloped immune system, altered mental status, risk of aspiration and higher use of invasive devices during their hospitalization. In our study we aimed to measure the burden of MDR in pediatric NICU patients. We also identified the type of organisms leading to MDR and risk factors leading to MDR.

Methods: Our manuscript adheres to applicable STROBE guidelines. This prospective observational cohort study enrolled all postoperative neurosurgical pediatric patients aged between 1-18 year admitted in neurointensive care unit during one year period from 1st January 2020 to 31st December 2020. The samples of blood, urine, pus, CSF and tracheal aspirates were sent for microbiological culture if there were clinical signs and symptoms of pneumonia, BSI or UTI after mechanical ventilation or indwelling device for at least 48 hours. We noted MDR infection rate, type of organism and risk factors associated with MDR infection. The total number of patients admitted during the study period, total number of patient-days, total number of patients with each device, total number of device-days, and number of patients with each device-associated infection were counted. Pearson Chi square test and Fisher’s test were used for statistical analysis. The value of P<0.05 was considered significant.

Results: 274 pediatric patients were investigated with a total of 1790 patient days in one year. The overall MDR infection rate was17.3/1000 patient days. Klebsiella pneumonia was the commonest MDR pathogen (38.7%) with BSI being the commonest (32.3%) source of infection. The length of NSICU stay, the duration of mechanical ventilation >5 days, emergency invasive surgery, cardiac and respiratory comorbidities, poor nutrition status were associated with MDR infections (P<0.05) (Table 1). The device utilisation ratio and devise associated MDR infection rate are tabulated (Table 2).

TABLE 1 - Association of Risk Factors With Multidrug Resistant Infections
Factors P value Odd’s Ratio[CI]
Age <2 y 0.402 1.871 [0.43-8.08]
Gender 0.681 1.232 [0.45-3.33]
Poor socioeconomic status 0.330 1.884 [0-53-6.30]
Poor nutrition status 0.0001 6.312 [2.31-17.20]
Mech ventilation > 5 d 0.665 1.276 [0.42-3.85]
Length of ICU stay >3 d 0.0001 6.2 [2.12-15.21]
Comorbidities (card/resp) 0.0001 12.2 [3.11-47.93]
Emergency invasive surgery 0.045 0.096 [0.01-0.94]

TABLE 2 - Device Utilization Ratio and Device Associated MDR Infection Rate
Parameters Device Utilization Ratio Device associated MDR infection rate (per 1000 device days)
Central line 0.24 4.7
Ventilator 0.18 15.5
Urinary catheters 0.21 19.0
EVD/Shunts 0.14 12.1

Conclusion: In our study the overall MDR infection rate is 17.3/1000 patient days in pediatric NICU patients. Klebsiella pneumoniae is the commonest MDR organism with blood stream being the commonest source of infection

[SNACC-98] Safety and feasibility of distraction procedure in growing rods for Early Onset Scoliosis as day care procedure - A retrospective observational study of 653 procedures

MB S, Khanna P, Garg B. AIIMS, New Delhi, India

Purpose: To investigate the safety and feasibility of growth rod distraction procedure as ‘daycare surgery’ in early-onset scoliosis (EOS). EOS is an ‘enigma’ in spine surgery as early fusion and deformity correction will negatively affect truncal growth and pulmonary development. Likewise, delaying the treatment would lead to grotesque deformity with severe systemic implications. Therefore, worldwide we use ‘Growth rods’ for EOS and periodically distract it to allow for spinal growth in a ‘controlled’ manner. However, regular distraction every 6 months until definitive fusion would incur huge financial challenges and resource utilization . Our hypothesis is that the growth rod distraction procedure can be routinely used as a daycare procedure, thereby, cutting down the cost and resource utilization, especially in these pandemic times.

Methods: Hospital records and operation notes were retrospectively reviewed of 119 patients with a focus on details of neurological events/complications during their index surgeries/lengthening procedures. Multi-modality IONM was used as a mandatory protocol in all our index cases . However, for growth rod lengthening procedures we had well-defined indications–i) patients in whom intraoperative drop in signals were present during index case ii)patients who had intraspinal abnormality and had synchronous neurosurgical procedure iii) patients who underwent rod exchange/revision surgery concurrent with lengthening procedure. Except for these indications, none of our patients had IONM during the routine lengthening procedure.An amplitude drop of greater than 50% in trans cranial MEP or somatosensory evoked potentials (SSEP) was considered a neuromonitoring ‘alert’.

Results: 653 procedures involving primary growing rod surgeries (119/653) and lengthening procedures (534/653) were performed in 119 patients with EOS with a mean age of 7.3+/−2.3 years. Traditional growing rods (TGR-454/534) or magnetically controlled growing rods (MCGR-80/534) were implanted and subsequent lengthening procedures (Average -4.7 (range 2-9)) were done at stipulated intervals (TGR- 6.5 months, MCGR -3.8 mo). The mean anesthesia to surgical time for TGR (96.6+/−23 min vs 41.3±12 min) and MCGR was done as an outpatient procedure with mean average time of 26.2+/−9 minutes, respectively. The mean average blood loss in TGR vs MCGR was reported as 108+/−38 mL vs 0 mL.None of the patients with rod lengthening procedures required blood transfusion or experienced a neuromonitoring alert.

On the morning of surgery these patients were admitted on short admission to Operating theatres and were not administered any pre-medication drugs. Induction was done using propofol (calm patients) or sevoflurane (restless patients) and BIS monitoring was done throughout the procedure. Intraoperative pain management was done using a fentanyl bolus. Furthermore, In the immediate post-operative period these patients were managed on fentanyl single bolus dose (0.5 microgram/kg) and later administered paracetamol injection (15 mg/kg - <30 kg) or ketorolac injection (0.1 mg/kg). At discharge, patients were managed on non-steroidal anti-inflammatory oral medications.

Average reporting pain control (VAS-1.3+/-0.78) was satisfactory and mobilization was initiated within 4 hours, postoperatively. All our patients were discharged on the same evening with oral analgesics. Our 30-day readmission was noted in 2/119 secondary to superficial wound infection, which was managed on oral antibiotics.

Conclusion: Growth rods (TGR, MCGR ) lengthening procedures can be safely undertaken as ‘daycare surgery’ under standardized anaesthesia and pain protocol. Secondly, intraoperative neuromonitoring can also be avoided in distraction procedures, thereby, helping in cost-cutting. This is especially relevant in changing paradigms of resource limitation in the COVID pandemic situation worldwide.

[SNACC-99] Should COVID-Positive Pregnant Patients with Thrombocytosis get Prophylactic Anticoagulation for Stroke in Labor?

Kumar M, Lee S, Yeh C. University of Illinois Chicago, Chicago, Illinois, United States

Clinical manifestation of coronavirus (COVID-19) is known to be associated with a hypercoagulable state and has a correlation of stroke as observed during the COVID pandemic. Pregnancy augments physiologic estrogenic effects on coagulation, making pregnant patients hypercoagulable. Management of hypercoagulability includes anticoagulation, which poses a contraindication to neuraxial anesthesia based on current guidelines. Management of primary labor anesthesia modality in patients with thrombocytosis can be challenging, particularly when presented with concurrent COVID infection. There is no guideline on the administration of anti-coagulation in this populace. The risk-benefit stratification of neuraxial anesthesia versus general anesthesia needs to be reviewed in such a patient population. We present a case of a parturient in labor who had thrombocytosis with a platelet of 576, COVID infection, and received therapeutic anticoagulation based on an automatic EMR best practices protocol. In this report, we examine literature surrounding the intersection of COVID, pregnancy, thrombocytosis and neuraxial anesthesia with respect to coagulation status to better guide anesthetic management in patients.

[SNACC-100] Single centre experience of intensive systolic blood pressure lowering in patients with spontaneous acute intracerebral haemorrhage

Iyer M*, Reddy U, Rula A*, Jogia M*, McNamara C*. National Hospital for Neurology and Neurosurgery, UCLH, London, United Kingdom*. Department of Neurocritical Care, NHNN 2. Institute of Neurology, UCL, London, United Kingdom

Background: Rapid lowering of an acutely elevated blood pressure following spontaneous intracranial haemorrhage (ICH) prevents haematoma expansion. However there are concerns that this could compromise perfusion to the perihaematoma region resulting in an ischaemic brain injury(1). Guidelines have recommended intensive systolic blood pressure (SBP) lowering <140 mmHg within 6 hours of symptom onset to reduce haematoma expansion and improve functional outcomes(2). We evaluated our experience of intensive SBP lowering in these patients and studied factors that are predictive of a poor neurological outcome.

Methods: We retrospectively collected data from a registered service evaluation of patients admitted to our Neurocritical Care Unit (NCCU) between 1st April 2019 and 28th February 2022. Patients were divided according to volume of parenchymal haematoma and presence of intraventricular extension of bleed. Primary outcome analysed was degree of functional disability on discharge from the NCCU, i.e. Modified Rankin Score (mRS) and secondary outcomes being NCCU length of stay (LOS), incidence of systemic complications, maintenance of target SBP, need for neurosurgical intervention and number of ventilated days. Receiver Operating Characteristics analysis and Pearson Chi squared analysis was used to determine statistical significance.

Results: During the study period, 220 patients were admitted with a diagnosis of ICH, of which 128 met the inclusion criteria for spontaneous ICH. Based on volume of bleed, 62 were categorised as large (≥30 mL), 53 as small (<30 mL) and 13 patients were excluded due to incomplete imaging data. There was a significant association (P=0.016) between large volume bleeds and poor outcomes (mRS >5). Early neurosurgical intervention (i.e. within the first 24 hours of admission) did not show any association with poor outcome, for both large (P=0.21) and small bleeds (P=0.76). Furthermore, there was no correlation between large volume of bleed and LOS on ICU (AUC i.e. Area Under Curve 0.577, P=0.16). In the first 7 days of admission, SBP control was defined as good if SBP was within target range for > 50% of time. Good control of SBP did not have a significant association with good outcomes for large volume (P=0.25) or small volume ICH (P=0.589). Poor SBP control did not have a relationship with poor outcomes in small bleeds (P=0.363) as well as with large bleeds (P=0.25, AUC 0.589). Median days of ventilation was 4.16 days in large volume and 0.875 days in small volume bleeds. There was no significant association between length of ventilation in both large (P=0.07) and small bleeds (P=0.47) with mRS outcomes. Acute kidney injury occurred in 26.9% of patients as a systemic complication of intensive SBP lowering. In 5% of patients cardiac complications such as electrocardiograph changes and transient elevation in troponin occurred during admission.

Conclusion: A large volume of haemorrhage is independently associated with a poor outcome (mRS >5), even in patients undergoing intensive SBP lowering in the acute phase of ICH. Having a longer stay in NCCU, and poor maintenance of BP also suggested a poor mRS outcome although not stastically significant. Good control of SBP showed a good predictive value of mRS on discharge despite not being statistically significant. These findings confirm that intensive SBP lowering in acute ICH is safe with regards to serious adverse events.

[SNACC-101] Standardization of Blood and Fluid Management within an Enhanced Recovery After Surgery (ERAS) Protocol in Major and Complex Spine Surgery: The Cleveland Clinic Experience

Manlapaz M, Koh Y, Krishnaney A, Winkleman R, Yokoi H. Cleveland Clinic, Cleveland, Ohio, United States

Introduction: Enhanced Recovery After Surgery (ERAS) is a multidisciplinary, comprehensive set of evidence-based interventions to reduce morbidity and accelerate postoperative recovery.1 Complex spine surgery carries high risks of perioperative blood loss, subsequent blood transfusion, and suboptimal fluid states. ICU admissions after deformity operations are common and frequently attributed to fluid overload, postoperative anemia, and need for postoperative vasopressors.2 In addition, perioperative blood transfusions are associated with increased postoperative risk of morbidity and mortality.3 Given the risks associated with blood transfusion and fluid imbalance, there is considerable interest in reducing the frequency of surgery-related transfusions and optimizing fluid management. ERAS has been successfully adapted for spine surgery by multiple institutions with data demonstrating a reduction in ICU admissions, hospital length stay (LOS), hospital costs, and intraoperative blood loss.1,4 We aimed to reduce the rate of blood transfusions and ICU admissions following complex spine surgeries at our institution by implementing a perioperative blood and fluid management standardization within the ERAS protocol.

Methods: A multidisciplinary team from Neurosurgery, Anesthesiology, and Blood Management developed and implemented a perioperative blood and fluid management algorithm within the Complex Spine Surgery ERAS protocol starting in 2018. Patients scheduled to undergo a major or complex elective spine surgery were referred to the blood management clinic if they were found to be anemic and were optimized to a preoperative hemoglobin goal of 13 g/dL with either iron or erythropoietin as appropriate. Intraoperatively, patients with no contraindications received a 10 mg/kg bolus of TXA followed by an infusion dose of 1 mg/kg/h, which was adjusted depending on renal function. The algorithm also follows a restrictive blood transfusion threshold set at a hemoglobin of 8 g/dL and encourages the use of cell salvage to allow autologous blood transfusion. Throughout the procedure, fluid administration was aimed at maintaining hemodynamic stability and adequate perfusion pressure (blood pressure within 10% baseline). Goal directed fluid management using pulse pressure variation (PPV) was used to assess fluid responsiveness during mechanical ventilation. A PPV threshold of 13% indicates that the stroke volume could be further optimized with administration of additional volume. If PPV is less than 13%, fluid boluses were avoided and vasopressors were utilized to augment blood pressure. A maximum of up to 2L of crystalloid solution was recommended and the use of colloids was encouraged, thereafter, to avoid tissue edema.

Results: 437 patients with similar baseline characteristics for complex spine surgery were identified, 217 cases before and 221 cases after ERAS protocol implementation. Following implementation of the ERAS protocol, the rate of perioperative blood transfusion decreased by 11.7% (P=0.007) and on average, there was a 680 mL reduction in crystalloids administered (P<0.001). Intraoperative blood loss decreased on average by 342 mL per case (P=0.001) and TXA use increased significantly by 25% (P<0.001). Postoperative ICU admissions declined by 8.5% (P=0.071) and the number of patients extubated within the OR increased by 13.3% (P=0.005).

Conclusion: ERAS represents a paradigm shift in perioperative management through integration of evidence-based practices into standardized algorithm of patient care. With quality improvement goals, we aimed to develop, implement, and analyze the effects of incorporating a perioperative blood and fluid management protocol on postoperative outcomes for complex spine surgeries. Our results suggest that a standardized, multidisciplinary approach is associated with reduced rates of blood transfusion and optimized fluid states which may lead to reduced ICU admissions and accelerated recovery for patients undergoing complex spine surgery.

[SNACC-102] Surgical Clipping of a Complex Superior Cerebellar Artery Aneurysm in a Patient with Sickle Cell Disease and Large Right-to-Left Shunt Using Rapid Ventricular Pacing

Budiansky A, Hjartarson E, Sinclair J. The Ottawa Hospital, Ottawa, Ontario, Canada. University of Ottawa, Ottawa, Ontario, Canada

Introduction: We describe the management of a complex patient with sickle cell disease and large right-to-left intracardiac shunt during surgical clipping of a superior cerebellar artery aneurysm using rapid ventricular pacing. Case Presentation: A 23-year-old male with sickle cell disease (SCD) was booked for an elective surgical clipping of an unruptured superior cerebellar artery (SCA) aneurysm. The aneurysm, measuring 2.3 ×2.9mm with a broad neck, was located at the basilar junction. The patient had history of pain crises, nephropathy and recurrent priapism, but no history of stroke or acute chest syndrome. A preoperative echocardiogram showed normal biventricular function and a patent foramen ovale (PFO) with a large right-to-left shunt, with no clear indication for closure.

Given the patient’s young age, SCD diagnosis and aneurysm anatomy, a decision was made to proceed with clipping rather than endovascular therapy.

Preoperative planning included discussion of options for softening the aneurysm to facilitate microdissection and clipping. While temporary clipping is commonly used, this would have been technically challenging given the aneurysm location. Furthermore, there was concern that vessel occlusion could increase the risk of embolic events and ischemia in the context of SCD. Cardiac standstill with adenosine or prolonged systemic hypotension were also felt to be unfavorable in this patient with large right-to-left shunt. Therefore, rapid ventricular pacing (RVP) was selected in order to obtain controlled yet brief periods of hypotension.

Under general anesthesia, a left subclavian 6Fr introducer sheath was inserted. A pacing electrode (Bard 6F, 100 cm) was advanced into the right atrium under fluoroscopic guidance. Further advancement of the pacing electrode into the right ventricle (RV) was technically challenging due to the large right-to-left shunt, which caused migration of the pacing electrode into the left atrium rather than RV. Insertion into the RV was ultimately successful, with confirmation of placement by fluoroscopy and capture noted at 0.6mA.

A left subtemporal craniotomy was completed. RVP was used at 200 beats per minute for a total of 6 times, for an average duration of 52 seconds (23 – 75s) and minimum 2-minute recovery between pacing episodes. This resulted in a mean arterial pressure (MAP) of 50 mmHg during pacing. To further optimize aneurysm relaxation, IV nitroglycerin in 50-100mcg doses was administered during pacing to achieve a MAP less than 40 mmHg. Fi02 was maintained at 100%. RVP was well tolerated, with rapid normalization of MAP after pacing cessation.

Using this technique, the plane between the SCA and aneurysm fundus was gradually developed until the proximal neck of the aneurysm was identified and perforating vessels were spared. The aneurysm was softened using RVP, allowing for successful placement of a permanent clip. Aneurysm obliteration was confirmed intraoperatively with indocyanine green and later by catheter angiography.

Perioperatively, the patient was kept normothermic, euvolemic and at his target hemoglobin. Hypertonic solutions were avoided to prevent sickling; instead, a lumbar drain was inserted to facilitate surgical exposure. The patient remained stable throughout the procedure.

The patient did not experience any cardiorespiratory complications or sickling events. However, he did suffer from recurring episodes of sickle-related priapism perioperatively, which required both urological intervention and postoperative exchange transfusion.

Discussion: SCD patients with intracranial aneurysms pose a challenge for the neuroanesthesiologist. Risks and benefits of endovascular versus surgical treatment must be weighed. The usual anesthetic approach to clipping must be balanced against risk of vaso-occlusive events. To optimize surgical conditions, we used RVP, a technique which allows for brief, controlled and safe hypotension. Other considerations included maintenance of adequate hemoglobin, temperature, hydration and avoidance of physiologic insults. Our case highlights the importance of actively monitoring for SCD complications, such as priapism, perioperatively.

[SNACC-103] The Effects of Sevoflurane on Neuron Apoptosis, GABAA Rα1/GABAA Rα2 in Hippocampus and Learning Ability of Neonatal Rat

Xie S, Wang K, Han R. Beijing Tiantan Hospital, Capital Medical University, Beijing, China

Objective: To investigate the effect of sevoflurane on neuron apoptosis, GABAA Rα1/GABAA Rα2 in hippocampus and learning ability, and try to analyze its possible neurotoxicity mechanisms in the developing brain.

Methods: The 120 neonatal Sprague-Dawley(SD)rats (7 d postnatal, P7) were randomly divided into 4 different groups: the control group (A), the sham anesthesia group (B), the saline+anesthesia group (C) and the Bumetanide+anesthesia group (D). The anesthesia treatment was a 4-hour exposure to the 0.8MAC(2.11% ) sevoflurane. The expression of the NKCC1, PARP-1 and GABAA Rα1/GABAA Rα2 in the hippocampus was tested by western blot 6 hours, 24 hours, and 72 hours after anesthesia, respectively. Then the Open-Field Test and Morris Water Maze Test were performed separately when the rats were 5-week-old, 8-week-old and 14-week-old.

Results: Compare to the group A, the expression of the NKCC1 of hippocampusin group C and B didn’t changed significantly, wheras the usage of Bumetanide before the anesthesia (group D) could inhibit the expression of the NKCC1 at 6h (56%±12%) and 24 hours (58%±8%) after the anesthesia significantly, P<0.05. The expression of the PARP-1 was increased at 6h after sevoflurane exposure in Group C (207%±20%, P<0.05), and the ratio of α1/α2 subgroup of GABAA was significantly increased at 6h (126%±6%), 24 hours (137%±6%), and 72 hours (184%±17%) after sevoflurane exposure (P<0.05) compared with the group A. The usage of Bumetanide (group D) may reverse the increase of PARP-1 and the ratio of α1/α2 subtype of GABAA. So there were no significantly difference of the above characters between the group B, D and group A. Rats exposed to sevoflurane (group C) had longer travel distance and time than group A and group B in Open-field Test when they were 5 weeks old (P<0.05), and the treatment of Bumetanide (group D) can only increase the activities of the plane orientation. When they were 8 weeks and 14 weeks old, rats from different groups make it uniformly. There was no significant difference in Morris water maze of space exploration task at any time.

Conclusions: The exposure of sevoflurane can induce the apoptosis of the neurons in early stage, influenced by the α1/α2 subgroup of GABAA increasing, and the α2 subtype can be transformed to α1 subtype. The sevoflurane may affect the adaptation and cognition of the environment in the short term. Usage of Bumetanidebefore the anesthesia can alleviate the effects of sevoflurane on neuron apoptosis,which may relate to the inhibition of NKCC1 and the transformation from GABAAα2subtype to α1 subtype in neonatal rats brain, and it also improve the learning ability decline caused by sevoflurane on neonatal rats.

[SNACC-104] The impact of anesthetic agents on regional cerebral blood flow during the carotid artery clamping

Nakano Y, Yoshitani K, Mauda S, Tsukinaga A, Ohnishi Y. National Cerebral and Cardiovascular Center, Suita, Osaka, Japan

Background: An animal model has mainly investigated the impact of anesthetic agents on cerebral blood flow(1). However, there is no evidence that cerebrovascular reserve is similar in human and animal models. There has been no method to measure CBF at the bedside. Using indocyanine green as a tracer, we developed the methodology to measure regional cerebral blood flow (rCBF) by near-infrared spectroscopy. Using the method, we investigated whether anesthetic agents (volatile anesthetics: desflurane or sevoflurane, and intravenous anesthetics: propofol or remimazolam) impact regional cerebral blood flow during the carotid artery clamping.

Methods: Patients undergoing thoracic endovascular aortic repair with Zone0, 1, and 2 with extra-thoracic debranching and carotid endarterectomy were enrolled. We measured rCBF before clamping the carotid artery, ten minutes after clamping, and after de-clamping by using NIRS and intravenous injection of ICG. rCBF was calculated by Fick’s principle using the maximum gradient model combining the change of arterial blood concentration (i) and maximum arterial blood concentration of ICG in the brain tissue (ii). First, the curve of the change in ICG concentration in the brain tissue was drawn using the software NIRO ICG (Hamamatsu Photonics, Japan). The original curve includes both arterial and venous components of the brain tissue. The curve of ICG concentration of arterial blood was separated by applying the frequency filter to the pulse wave component in the curve of ICG concentration (i). Second, the maximum blood concentration of ICG was obtained by DDG analyzer (Nihon Kohden, Japan) (ii). Combining the two results [(i) and (ii)], rCBF was calculated. We compared rCBF between the side with and without the cross-clamping of the carotid artery. We also assessed the impact of anesthetic agents on the cross-clamped side of the carotid artery. We performed a mixed linear regression analysis to evaluate the interaction between the side with and without cross-clamping of the carotid artery and between the volatile and intravenous anesthetic agents.

Results: Thirty patients with TEVAR and 25 patients with CEA were enrolled in this study. rCBF was measured in fifty-six patients at three points on the left and right sides of the forehead. r CBF was significantly decreased on the side of cross-clamping of the carotid artery (from 49.0±30.5 to 36.2±27.8 mL/min/100 g), but not on the side of no cross-clamping (from 49.9±35.0 to 56.7±30.8 mL/min/100g) (Fig. 1). There was a significant interaction between the side with and without the cross-clamping of the carotid artery. rCBF recovered to the baseline level on the cross-clamping side of the carotid artery (52.3±30.2 mL/min/100 g). In patients with volatile anesthetic agents, rCBF decreased from 48.8±34.4 to 37.9±32.7 mL/min/100g) and in patients with intravenous anesthetic agents from 49.2±25.0 to 33.7±19.2 mL/min/100 g) (Fig. 2). There was no significant interaction between the volatile and intravenous anesthetic agents (P=0.230).

F50
FIGURE 1:
Time course of change of rCBF between unclamped and cross-clamped side of the carotid artery.
F51
FIGURE 2:
The impact of anesthetic agents on rCBF of cross-clamped side of the carotid atrery.

Conclusions: There was a significant reduction of rCBF on the side of the cross-clamping of the carotid artery. There was no significant impact of anesthetic agents on the rCBF reduction during the cross-clamping of the carotid artery.

[SNACC-105] The impact of activities of daily living on the development of postoperative delirium in the elderly and very elderly patients who underwent surgery for femoral neck fracture

Ishida K*, Morioka, T, Umehara M, Kitagawa F, Sakamoto S, Murakami S, Matsumoto M. Kurashiki Central Hospital, Kurashiki, Okayama, Japan*. Japan Community Healthcare Organization Tokuyama Central Hospital, Shunan, Yamaguchi, Japan. Yamaguchi University Graduate School of Medicine, Yamaguchi, Prefecture, Japan

Background: The number of elderly and very elderly patients receiving surgical anesthesia is increasing, especially in Japan. These patients are likely to develop postoperative delirium (POD). POD makes patient care difficult and prognosis worse. Recent studies focus on prehabilitation and patients’ early recovery to prevent POD. Patients’ preoperative exercise may help reduce the incidence rate of postoperative complications, including perioperative neurocognitive disorder. However, it is difficult to performe prehabilitation for trauma patients with lower lower extremity fracture. In such cases, preoperative activities of daily living (ADL) may influence the development of POD. Here, we retrospectively investigated the relationship between the incidence rate of POD after femoral neck fracture surgery and preoperative ADL in the elderly and very elderly.

Methods: We included patients aged ≥70 years (no upper limit) who underwent femoral osteosynthesis or bipolar hip arthroplasty under general anesthesia. Those with a preoperative diagnosis of dementia were excluded. Patients’ background, complications, preoperative ADL (clinical frailty scale and the level of care needed), hospitalization before coming to our hospital, and days from fracture to surgery were examined for risk factors for POD. Perioperative factors, including existing preoperative delirium, preoperative blood examination, urinary catheterization, physical restraint, dietary restriction, sleep disturbance, perioperative pain, duration of surgery, duration of oxygen administration, and time to initiation of rehabilitation, were also examined as risk factors for POD. Delirium was assessed by the intensive care delirium screening checklist (≥4 points). Data are expressed as mean±standard deviation, median [interquartile range], or patients ‘number. Unpaired T-test (normal distribution dada), Mann–Whitney U test (non-normal distribution data), and Chi-squared test were used for statistics. P<0.05 was set as significant.

Results: Fourteen (25%) of 56 eligible patients had POD (POD group, aged 86±7 y). The POD group, in comparison with the non-POD group (42 patients, aged 84±8 y), had more patients with the clinical frailty scale ≥5 (6/14 vs. 7/42, P<0.05), the level of care needed grade ≥1 (10/14 vs. 8/42, P<0.01) and preoperative delirium (7/14 vs. 3/42, P<0.01). There were no significant differences in preoperative hospitalization, time to surgery (5[3-6] vs. 6[4-7] days), urinary catheterization, physical restraint, sleep disturbance, anesthesia method, duration of surgery (58 [40-72] vs. 56 [45-82] min), and time to initiation of rehabilitation (Table 1).

T18
TABLE 1

Discussion and conclusion: It has been pointed out that cognitive decline may be associated with ADL decline and that ADL decline may cause further decline in cognitive reserve. Thus, preoperative ADL decline may easily develop delirium even in the preoperative period, leading to POD in such aged patients. It is important to recognize that preoperative ADL decline in the elderly and very elderly is a risk factor for POD. However, prehabilitation is hard to perform in such aged femoral neck fracture cases. Shortening the days from fracture to surgery may be one of the strategies for reducing the incidence rate of preoperative and postoperative delirium.

[SNACC-106] The role of continuous intravenous lidocaine on brain relaxation, opioid consumption, and surgeon’s satisfaction in an adult population undergoing craniotomy tumor surgery: Randomized controlled trial

Omega A, Chandra S, Pryambodho P. Universitas Indonesia, Jakarta, Indonesia

Background: Brain relaxation after dura opening is essential in craniotomy removal tumor. Lidocaine decreases cerebral metabolic rate of oxygen (CMRO2), cerebral blood flow (CBF), and cerebral blood volume (CBV); and can potentially reduce intracranial pressure (ICP), resulting in excellent brain relaxation after dura opening. Lidocaine has analgesic and anti-inflammatory effects. However, there is no study that analyzes continuous intravenous lidocaine infusion on brain relaxation, intraoperative opioid consumption, and surgeon’s satisfaction in adult patients undergoing craniotomy tumor removal.

Methods: A double-blind, randomized controlled trial with consecutive sampling was performed. Sixty subjects scheduled for craniotomy tumor removal were enrolled. Subjects received either an intravenous bolus of lidocaine (2%) 1.5 mg/kg before induction followed by 2 mg/kg/h continuous infusion up to skin closure (lidocaine group) or a placebo with a similar volume (NaCl 0.9%). Brain relaxation and surgeon’s satisfaction were evaluated by a neurosurgeon with a four-point scale, total intraoperative opioid consumption was recorded in mcg and mcg/kg/minute.

Results: All sixty subjects completed the study. Lidocaine group showed better brain relaxation after dura opening (96.7% vs 70%; lidocaine vs placebo, P<0.006), less intraoperative fentanyl consumption (369.2 mcg vs 773.0 mcg; P<0.001, 0.0107 vs 0.0241 mcg/kg/minute; lidocaine vs placebo, P<0.001), and good surgeon’s satisfaction was higher in lidocaine group (96.7% vs 70%, P=0.006). No side effects were observed during this study.

Conclusions: Continous lidocaine intravenous infusion administration improves brain relaxation after dura opening, and decreases intraoperative opioid consumption, with good surgeon satisfaction in adult patients undergoing craniotomy tumor removal.

[SNACC-107] The Use of Neuromonitoring for Initial Detection and Surveillance of Compartment Syndrome during Posterior Fossa Craniotomy

Philip J, Kinthala S, Halula A, Kapoor N. Robert Packer Hospital, Sayre, Pennsylvania, United States

Infiltration of peripheral venous catheters can rarely result in compartment syndrome of the affected extremity leading to neurovascular impairment and consequently limb ischemia and limb loss.

Here we will discuss the case of a 55 year-old male patient that underwent an elective posterior fossa craniotomy with neuromonitoring. The patient developed iatrogenic compartment syndrome of the forearm caused by venous catheter infiltration.

Following successful induction and intubation, the patient was placed in the prone position, and the functionality of the intravenous and arterial catheters was confirmed. Later in the case the left forearm 18-gauge intravenous catheter had moderate resistance. We initially attributed the resistance due to positioning , external pressure from the safety belt across the arm and pressure from the surgical team leaning on the patient’s arm and shoulder. During the procedure, when the somatosensory signals of the left ulnar nerve and the motor signals of the left first dorsal interosseous muscle were lost, the neurophysiologist notified the neurosurgeon and the anesthesia team. Once the surgical cause was ruled out, the surgery was paused, and the arm was evaluated for vascular or mechanical compression. On clinical examination, the left forearm was very tense, with no palpable pulse and no adequate waveform exhibited with the use of pulse oximetry. A clinical diagnosis of acute compartment syndrome was made.

Considering this, the neurosurgeon proceeded with the resection of the fourth ventricle tumor, as opposed to further delaying the surgery for a proper consult and management of compartment syndrome. The team decided to reassess the arm in 2 hours. During this time, the anesthesiology team worked with the neurophysiologist to continuously monitor for any progression or improvement in motor and somatosensory signals.

In about 2 hours, the somatosensory signals returned, and surgery was paused for evaluation of the arm by the trauma surgeon, which was reassuring. After about 5 hours after the loss of motor evoked potentials, signals began to return to the left first dorsal interosseous muscle.

In this case, the neuromonitoring alerted us to a proper diagnosis and helped continuous surveillance of compartment syndrome. This information helped us to continue with conservative management and avoided delaying the surgery during a critical phase for an emergent fasciotomy (Fig. 1 and 2).

F52
FIGURE 1:
Yellow circle depicting the sudden loss of signal of left ulnar somatosensory evoked potentials at 12:24 and return to baseline at 14:51.
F53
FIGURE 2:
Yellow circle depicting the sudden loss of signal from motor evoked potentials of the left first dorsal interosseous muscle in hand at 12:29. Signals return about 5 hours later at 17:26.

[SNACC-108] To Determine the Incidence and Risk Factors of Post-Operative Pulmonary Complications after Craniovertebral Junction Anomaly Surgery

Jangra K, Depuru A, Barik A, Soni S, Bhagat H, Palliwal S. Postgraduate Institute of Medical Education and Research, Chandigarh, India

Background: Craniovertebral junction (CVJ) anomalies are the disorders affecting the cervical vertebral column that encloses neuraxis at the junction of the cranium and vertebral column. Symptoms are attributable to pressure on neural tissues due to various bony abnormalities. The respiratory system is usually affected in these patients due to central respiratory depression, and weakness of respiratory muscles leading to inadequate cough, retention of secretions, and pneumonitis. The general anaesthesia and surgical intervention can further deteriorate the respiratory reserves and may lead to pulmonary complications postoperatively. Hence, this study was conducted to determine the incidence of postoperative pulmonary complications (PPCs), various risk factors contributing to PPCs, and to evaluate the association between the preoperative pulmonary reserve and postoperative pulmonary complications.

Materials and Methods: This prospective, observational study was commenced after getting approval from Institutional Ethics Committee and obtaining written informed consent. We enrolled the patients between the age of 12 to 65 years, with CVJ anomalies posted for surgery. The various clinical parameters and laboratory tests used to assess preoperative pulmonary reserves included respiratory rate, chest expansion, single breath count (SBC), breath-holding time (BHT), arterial blood gas analysis (ABG), and pulmonary function tests (PFTs). PPC was defined by the presence of fever, cough, need for respiratory support for more than 24 hours or tracheostomy, pneumonitis and abnormal chest x-ray.

Results: A total of 41 patients were recruited for this study. The incidence of PPC was 26.8% with pneumonitis being the highest (63%). Laboratory preoperative PFTs including FVC, FEV1/FVC, FEF 25-75%, and PEFR, were comparable amongst patients with PPCs and without PPCs with P values of 0.099, 0.186, 0.064, 0.064, and 7.48, respectively. Preoperative bedside PFTs were found to be statistically significant to predict PPCs with the P values of 0.045, 0.001, and 0.012 for BHT, SBC, and chest expansion, respectively. Amongst the various intraoperative parameters, the patients with more severe blood loss were associated with a higher rate of PPCs (P=0.013). Follow up after 3 months of surgery showed a slight improvement in pulmonary function.

Conclusion: The incidence of PPC following CVJ surgery was 26.8%. Bedside PFTs were found to be significantly superior to PFTs using spirometry in predicting the PPCs. The intraoperative risk factor for predicting PPCs was excessive blood loss. Pulmonary function improves after surgery following initial deterioration.

[SNACC-109] To establish correlation between inferior vena cava collapsibility index and carotid doppler flow time with cardiac output in patients undergoing intracranial tumour surgeries

Prabhakar H, Das K, Kumar N. All India Institute of Medical Sciences, New Delhi, India

Background: Assessment of fluid status remains largely empirical. Traditional parameters such as blood pressure, heart rate is neither specific nor sensitive. Static indices, including central venous pressure have been criticised for a lack of accuracy in predicting fluid responsiveness despite their invasive nature. Moreover, the invasive arterial catheterisation can be unpleasant in awake patients. There is a recent trend towards use of non-invasive method such as ultrasound parameters to assess fluid status. As there are very few studies regarding use of carotid ultrasound as well as inferior vena cava measurements together in neurosurgical population, we conducted a study to find any correlation between carotid flow time, inferior vena cava collapsibility index and cardiac output as well as observe whether there is any significant change in these parameters following a fluid challenge. Our primary objective was to assess changes in inferior vena cava collapsibility index(IVCCI) and carotid flow time(CFT) as well as cardiac output(CO) measured by Flo-trac EV-1000 following a fluid challenge in patient undergoing brain tumour surgery.

Methods: Total 40 patients, aged 18 to 60 years having brain tumour scheduled for surgery were enrolled. After attachment of monitors radial artery was cannulated and attached to Flo-trac EV-1000. Baseline cardiac output were noted from Flo-trac machine while patient was lying with torso at 45°. Two trained operators with experience of minimum 25 ultrasonographic recordings of the above-mentioned parameters on healthy volunteers prior to the study, recorded IVCCI and CFT separately. Baseline IVCCI was recorded by using a phased array probe of 1-5 MHz ultrasound transducer via subcostal window just distal to IVC-hepatic vein junction. Baseline CFT was also recorded by using linear 6-13 MHz probe placed longitudinally over carotid artery on the neck. After that patient’s torso was lowered to horizontal position and 500 mL of crystalloid was transfused rapidly over 3-5 minutes, following which patient was again positioned in supine with torso at 45° and all the three above mentioned readings were recorded in the same order as above. After all these measurements patient was anaesthetised as per the discretion of the concerned anaesthesiologist.

Results: We observed significant increase in cardiac output after administration of fluid from (5.95±1.16 L/min) at baseline to (6.76±1.75 L/min) following fluid challenge. There was a significant decrease in IVCCI from baseline (44.50±17.03%) to (26.21±13.60%) following fluid challenge.(P<0.001) We also observed significant increase in CFT from baseline (7.21±2.37 ms) to (10.49±1.85 ms) following fluid challenge (P<0.001). There was no significant correlation between CO, IVCCI and CO (P>0.05) Neither IVCCI nor CFT could predict fluid responsiveness independently.

Conclusions: We found that all these parameters CO, CFT, IVCCI change significantly following a fluid challenge suggesting all these parameters as promising indicators for assessing fluid response. In this study we were unable to find any correlation between CO, CFT, IVCCI at any point of time.

[SNACC-110] Too Sick for Anesthesia: Management of an Endovascular Thrombectomy with Unstable Cardiac Rhythm

Chyfetz M. Albert Einstein College of Medicine, New Rochelle, New York, United States

Mechanical Thrombectomy (MT) has become Standard of Care for management of acute ischemic strokes secondary to large intracranial vessel occlusions. A patient typically presents emergently to the Neuro-interventional suite immediately following diagnosis without a formal cardio-pulmonary evaluation and optimization as “time is brain.” We present the case of an 81-year-old-female with history of atrial fibrillation brought in by ambulance from assistant living with a cardioembolic right MCA occlusion. Given high NIHSS score, high ASPECTS score and favorable CT-perfusion mismatch ratio, administrative consent was obtained by Neuro Interventionalist and Stroke Neurology. Patient arrived in unstable Atrial Fibrillation with RVR and EKG changes significant for acute myocardial ischemia. A patient with an unstable medical condition warrants a multidisciplinary discussion prior to proceeding with mechanical thrombectomy as the risks of anesthesia may not be permissible. We further review the risks and benefits of sedation versus general anesthesia in a high-risk patient presenting as a thrombectomy candidate and highlight preoperative optimization strategies which allow for minimal delay to groin puncture while promoting an optimal patient outcome.

[SNACC-111] Treatment Refractory Hypertension During Superficial Temporal Artery-Middle Cerebral Artery Bypass In The Setting of Moyamoya Disease

Johnston M, Kerfeld M. Mayo Clinic, Rochester, Minnesota, United States

The patient is a 41 year old female with past medical history significant for moyamoya angiopathy with prior occlusive stroke, chronic low back pain with opioid use disorder, hepatitis C, HTN, and morbid obesity. She presented for STA-MCA bypass for R MCA distribution strokes with recurrent symptoms despite optimized medical management. Her presentation was also complicated by low back pain treated with TID buprenorphine. The patient’s hypertension was managed with lisinopril which was discontinued in the months leading up to surgery. The anesthesia plan included indirect intubation with SL ETT, 2 large bore peripheral IVs, and invasive arterial blood pressure monitoring postinduction. MEPs and SSEPS were collected throughout the procedure. Induction was performed with lidocaine, high dose propofol, and remifentanil. Anesthetic was maintained with high dose propofol and high dose remifentanil. As we approached the time of anastomosis, blood pressure became labile, gradually increasing to a peak of systolics >200 despite addition of fentanyl boluses, ketamine, clevidipine boluses and infusion, labetalol, hydromorphone, and 1 MAC of sevoflurane. Decision making was complicated by the importance of controller hypertension was weighed against the risk of hypotension in the setting of a new and potentially tenuous STA/MCA anastomosis. Additionally, we weighed the importance of anesthetics for blood pressure control vs their effects on neuromonitoring fidelity.

[SNACC-112] Ultrasound-guided superficial cervical plexus block for postoperative pain relief following anterior cervical discectomy & fusion surgery

Gupta D, Srivastava S, Trivedi N, Verma R, Mishra P. Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow, Uttar Pradesh, India

Background: Anterior cervical discectomy and fusion (ACDF) surgery is widely used to treat nerve root or spinal cord compression by decompressing the cervical spinal cord and nerve roots with a discectomy to stabilize the corresponding vertebrae. The incidence of persistent neck pain after an ACDF procedure varies throughout the literature with majority of patients reporting moderate to severe post-operative pain with long term effect 1. Superficial cervical plexus block (SCPB) is a safe and simple technique that has been shown to provide good pain relief for both incisional pain and the occipito-nuchal pain after thyroid and carotid surgeries 2.

Therefore, we planned a prospective randomized control study to evaluate ultrasound-guided SCPB using 10 mL of 0.25% ropivacaine after induction of anesthesia with primary objective of perioperative opioid consumption and secondary objectives of PONV scores, dysphagia & sore throat scores, the Quality of recovery (QoR-15) scores 24 hours post-operatively and Neck disability index (NDI) scores during discharge & at 3- months after surgery following ACDF surgery.

Methods: This study was conducted after approval from Institutional Ethical Committee (IEC code number- 2020-67- MD-EXP-15), registration in Clinical Trials Registry of India (CTRI number- CTRI/2020/08/027126) and written informed consent from the patient from June 2020 to December 2021. A total of 46 patients belonging to ASA-PS grade I-III and 18-65-years age of either sex were included scheduled for ACDF surgery under general anesthesia. Patient having history of allergy to local anaesthetics, known psychiatric or neurological illness or pregnant patient were excluded.

Following induction of anaesthesia, patients were divided into 2 groups of equal numbers using a computer-generated randomization method.

Experimental/study group: Patient received 10 mL of 0.25% ropivacaine in Ultrasound guided bilateral SCPB.

Control group: Patient received 10 mL of normal saline in bilateral Ultrasound guided SCPB.

Thereafter, respective surgery was performed as per our institute standard guidelines. Post operative pain management of the patient was using patient-controlled analgesia via IV-PCA pump with only demand doses (no baseline infusion). The aim was to maintain a VAS of <4. After 24 hrs postoperatively, once patient started orally, he/she was prescribed acetaminophen 500 mg 6 hourly. All the observations were measure by independent observer blinded to group allocation.

Results: Demographics of the patients belonging to 2 groups were similar. Primary outcome: The intraoperative fentanyl requirement [95% CI- 68.32% to 94.71%; P<0.001], post-operative fentanyl consumption [95% CI-45.82% to 69.39%; P<0.001] and total fentanyl consumption in 24hrs post-operatively [95% CI- 123.49% to 154.76%; P<0.001] were significantly decreased among experimental group compared to control group.

Secondary outcome: VAS scores at 2 hours,4 hours,8 hours and 24 hours were found to be significantly lower in the experimental group as compared to the study group (P≤0.001). PONV scores at 24 hours postoperatively were found to be significantly better in experimental group compared to control group (P<0.001). However, there was no difference in the dysphagia and sore throat between the groups. Post-operative QoR-15 scores (out of 150) were found to be higher in the experimental group as compared to the control group (P<0.001). The neck disability scores (out of 50) were found to be significant lower in the experimental group, both at discharge and at 3 months post- operatively in comparison to the control group (P=0.002 and P<0.001 respectively).

Conclusion: Thus Ultrasound-guided bilateral Superficial Cervical plexus block (SCPB) was found to be effective in our study settings to better post-operative pain profile, QoR-15 Score and NDI scores in the patients posted for ACDF surgery under general anesthesia.

[SNACC-113] Urgent Surgical Resection of a Metastatic Catecholamine-Secreting Paraganglioma Causing Thoracic Spinal Cord Compression

Evans T, Hunter L. Mayo Clinic, Rochester, Minnesota, United States

Introduction: Anesthetic management of patients with a history of catecholamine-secreting paragangliomas has many considerations and challenges, especially in the setting of limited preoperative evaluation and preparation. We describe a case of a patient with acute spinal cord compression due to a metastatic catecholamine-secreting paraganglioma.

Case Description: A 47-year-old man with history of a catecholamine-secreting paraganglioma presented for urgent surgical resection and thoracic spine fusion due to metastatic tumor causing acute spinal cord compression. He had a history of a resected left retroperitoneal catecholamine-secreting paraganglioma 10 years prior. Over several years, repeat imaging demonstrated increasing tumor growth of multiple metastatic thoracic spine lesions, and he began to experience worsening pain related to these tumors. He then developed acutely worsening bilateral truncal and lower extremity paresthesias and weakness, and magnetic resonance imaging of the thoracic spine demonstrated tumor causing severe thoracic spinal cord compression. He was admitted to the intensive care unit (ICU) for initiation of medical therapy and hemodynamic and neurologic monitoring. He was evaluated by colleagues in orthopedic oncology and endocrinology. He described intermittent episodes of palpitations and increased sweating weeks leading up to his admission. Upon admission he had an elevated systolic blood pressure. Endocrinology advised against biopsy of the lesion, noting that even needle biopsy could trigger significant catecholamine release as the patient had not been taking any medications to block catecholamines. The orthopedic oncology team recommended surgical decompression of the spinal cord to avoid worsening neurologic injury acknowledging the high-risk nature of the procedure given the potential sequelae of catecholamine release. In preparation for the procedure, the endocrinology team recommended starting metyrosine and alpha blockade with phenoxybenzamine. 24 hours following admission, the patient was hemodynamically optimized and underwent thoracic tumor resection and posterior instrumented fusion from thoracic levels 3 to 7. Hemodynamic lability was managed with multiple medications, including clevidipine, esmolol, magnesium, norepinephrine, phenylephrine, and vasopressin. A period of heavy blood loss occurred during tumor excision resulting in initiation of vasopressors and transfusion of blood products. Following the procedure, he was extubated and transferred to the ICU. Phenoxybenzamine and metyrosine were discontinued. He required an intermittent norepinephrine infusion to augment mean arterial pressure for spinal cord perfusion. Over the course of his hospital stay, he had gradually improved bilateral lower extremity motor function and sensation, and he was discharged from the hospital to an acute rehabilitation service.

Discussion: Catecholamine-secreting paragangliomas can pose many challenges to the anesthesiologist, and undiagnosed and undertreated tumors can present with significant anesthetic morbidity and mortality. Ideally, the patient will have a thorough preoperative evaluation and preparation, including basic lab work, complete cardiovascular evaluation with electrocardiogram and echocardiogram, and hemodynamic optimization with antihypertensives.1 This case required multidisciplinary discussion with involved teams and the patient with regards to weighing the risks of proceeding with surgery in the setting of potentially worsening neurologic decline.

[SNACC-114] Use of Heart Rate Variability In Aneurysmal Subarachnoid Haemorrage in Predicting Complications and Clinical Outcome: A Systematic Review

Agrawal S, Chowdhury T, Subramaniam S, Venkatraghavan L, Englesakis M. Toronto Western Hospital, Toronto, Ontario, Canada

Background: It is a well-known fact that aneurysmal subarachnoid hemorrhage(aSAH) can cause imbalance between the sympathetic and parasympathetic nervous systems. These perturbations may cause various changes in multiple organ functions and eventually present as a wide array of complications. In addition, these changes are also linked with poor outcome in such patients. Various methods were investigated to measure the integrity of the autonomic nervous system both quantitatively and qualitatively. HRV as a diagnostic tool for autonomic dysfunction and its association with clinical outcome is extensively studied in patients with aSAH. However HRV as a reliable predictor of clinical outcome in aSAH is not well described. Thus we planned this systemic review of available literature evaluating HRV as clinical predictor for complications and clinical outcome.

Methods: The systematic review was registered with PROSPERO( International register of prospective reviews). The steps in this review involved preliminary searches, piloting of the study selection process, formal screening of the results against the eligibility criteria, data extraction, quality assessment and analysis of data. The protocol was developed following the PICOS (Problem, Intervention, Comparator, Outcome and setting question). Whether the HRV indices play a role in predicting the various complications associated with aSAH and to determine the association of HRV indices in relation to outcome in patients with aSAH forms the basis of this systematic review. The review was performed based on the Preferred Reporting Items for Systematic reviews and Meta-analyses (PRISMA) guidelines for systematic reviews.

Inclusion criteria included prospective studies, randomized control studies, retrospective studies that evaluated the use of HRV in aneurysmal sub arachnoid patients, intracranial aneurysm surgery patients and in aneurysm coiling patients. Case reports, studies that have less than 10 patients, obstetric, patients less than 18 years of age and non-english studies and studies which report on other techniques of HRV analysis ( Entropy ) were excluded. The librarian conducted the search in the following databases: MEDLINE, PubMed, Embase, Cochrane central register for controlled trials, Cochrane database for systematic reviews from the dates January 1st 1996 to April 30th 2020. On the basis of the above defined search terms, initial titles and abstracts were collected from the librarian. After successive screening based on the inclusion and exclusion criteria, the final full articles were used for data collection.

The primary objective of this review was to know the role of time domain and frequency domain indices of HRV in predicting various complications associated with aSAH. The secondary objective was to determine the association of HRV indices in relation to outcomes.

Results: After conducting the search in the following databases: MEDLINE, PubMed, Embase, Cochrane central register for controlled trials, Cochrane database for systematic reviews from the dates January 1st 1996 to April 30th 2020, we have selected 12 studies into the final results which looked into the primary and the secondary criteria. Out of 12 studies, 11 studies have shown that the patients who developed the complications after aneurysmal subarachnoid hemorrhage had changes in the Heart Rate Variability as measured by either time domain or the frequency domain reflecting either increase in sympathetic or parasympathetic activity post bleeding. However, 1 study has shown no relationship between HRV and the complications but, with increased 1 year mortality.

Conclusion: Heart Rate Variability is an important noninvasive bedside clinical tool for rapid and early detection of complications associated with the Aneurysmal Subarachnoid Hemorrhage and the clinical outcome. Effective use of Heart rate variability in the neurosurgical ICU can be utilized in predicting the complications and acting in advance to minimize it’s deleterious effect, minimize ICU and hospital stay and patients clinical outcome.

[SNACC-115] Use of Peripheral Norepinephrine in Extracranial-Intracranial Bypass surgery for Moya-Moya

Teixeira M, Fatima B, Savastano L, Klaas J. Mayo Clinic, Rochester, Minnesota, United States

Abstract

Background: Moyamoya is a progressive disease characterized by stenosis or occlusion of cerebral vasculature. The goal of surgical treatment through extracranial-intracranial (EC-IC) revascularization is to reduce the risk of ischemic stroke by improving cerebral circulation. Neuroanesthesiologists demonstrate a significant role in ensuring exquisite blood pressure control for optimal intraoperative cerebral perfusion. Due to concern of extravasation of vasopressors and simultaneous injury to the tissues, phenylephrine through a peripheral intravenous line (PIV) is traditionally used as first line. However, norepinephrine (NE), as a mixed vasoconstrictor and inotrope has preferred pharmacodynamics over pure alpha-agonists given its ability to increases arterial pressure, mean systemic filling pressure, cardiac contractility, and cardiac output. Its widespread use in the operating room has been limited due to inconvenience of central venous catheter placement. The aim of this study is to evaluate the safety and feasibility of NE use through PIV compared to the use phenylephrine (PHENYL) through PIV access.

Methods: After approval from institutional review board, we identified patients from an internal database undergoing surgical management for Moya Moya disease between 2021 to 2022 at the Mayo Clinic. We stratified patients into two groups based on vasopressor used; NE group (n=9) and PHENYL group (n=24); and compared the risk of extravasation and subsequent tissue injury.

Results: Our cohort comprised patients with an average age of 41 years. 68% patients were female (n=21) and all (100%, n=31) suffered preoperative cerebrovascular accidents (CVAs). Invasive arterial blood pressure was monitored and maintained according to institutional guidelines ensuring mean arterial pressure at least >65 or above baseline blood pressure. This was achieved by use of NE or PHENYL through PIV access in each group. Among these patients, PIV access was obtained by ultrasound guidance in 16% (n=5) patients. Most patients had ≥18-gauge PIV (90%, n= 28). We found no extravasations documented intraoperatively in both groups.

Conclusion: In this surgical cohort, preliminary data suggests no difference from a safety standpoint in use of NE or PHENYL through careful PIV access placement and monitoring. More research is needed to determine whether cerebral perfusion pressure is improved with mixed alpha-beta agonists such as norepinephrine.

References:

Brenton, F, Scott, M et al Time to Use Peripheral Norepinephrine in the Operating Room. Anesthesia & Analgesia: July 2021 - Volume 133 - Issue 1 - p 284-288. PMID 33886514.

Ueki K, Meyer F, Mellinger J. Moyamoya disease: the disorder and surgical treatment. Mayo Clin Proc. 1994;69(8):749. PMID 8035631

[SNACC-116] Ventilation During Posterior Spinal Fusion With Incidentally Found Hemidiaphragm

Sandhu S, Vincent A. George Washington University Hospital, Washington, DC, United States

Unilateral diaphragmatic paralysis occurs when one side of the diaphragm becomes weak or paralyzed. There are many etiologies of this pathology, most commonly congenital or phrenic nerve disruption. We present a case of an emergent T12-L4 posterior spinal fusion after traumatic L2 vertebral body fracture with retropulsion of osseus fragments in a patient incidentally found to have a left hemidiaphragm with abdominal contents within the thoracic cavity. Upon entry to the operating room, it was unknown what led to the hemidiaphragm.

Patient is a 35-year-old male with history of lymphoma and end stage renal disease requiring hemodialysis. He was transferred to our Level One Trauma Center after a motorcycle accident resulting in the subsequent injuries - Lamina papyracea fracture, multiple rib fractures, L2 vertebral body fracture with retropulsion of osseus fragments, and left eyelid laceration. He was pale on examination, but vital signs stable and he was able to follow commands. Breath sounds were found to be complicated by borborygmi signs in the left upper and middle lobes with auscultation.

Although often asymptomatic, symptoms of hemidiaphragm can range from dyspnea to respiratory failure. Depending on severity of the paralysis, abdominal contents may be present within the thoracic cavity and thus present unique challenges for ventilation when such patients require intubation for surgical procedures. In this case we look at our polytrauma patient’s unique airway management for intubation and ventilation under general anesthesia for a neurosurgical procedure.

Standard ASA monitors were applied and IV access was obtained. Once surgeon was in the room, patient was induced with propofol and intubated with 7.5 ETT without issue. Upon auscultation adequate lung sounds were heard on the right and diminished on the left as expected. Alternative plans were in place for one lung ventilation if patient’s airway pressures remained high. The patient was maintained in log roll spinal precautions and flipped into prone positioning. Lung protective ventilation parameters were used, and he was placed on volume control settings with tidal volumes set to predicted body weight of 6 mL/kg and a PEEP of 5. Oxygen saturation was stable throughout the case with FiO2 0.5. Anesthesia was initially maintained with both a propofol infusion and desflurane until hemodynamic changes caused a high requirement of vasopressor support, including vasopressin, phenylephrine, and norepinephrine, at which time the propofol was discontinued and a MAC of <0.5 was achieved with desflurane.

Erector spinae blocks were placed at T5 bilaterally for analgesia of the multiple rib fractures. Vasopressor support was weaned at the conclusion of the case and extubation proceeded without complication. On the following day, the patient was sitting upright, eating breakfast, and noting he had no pain from the rib fractures and mild to moderate pain at surgical site.

Unilateral hemidiaphragm paralysis is often overlooked as many patients remain asymptomatic until the condition is incidentally found or is exacerbated by additional pathologies such as traumatic rib fractures. In such cases, when patient must undergo extensive surgical procedures, using lung protective strategies with a plan for alternative ventilation if these proved prohibitive in a ruptured diaphragm provides a safe and adequate anesthetic plan. As well, having adequate postoperative pain control, particularly with an opiate-sparing regional plan, can avoid the onset of pneumonia and other opiate or hypoventilation risks to the patient.

[SNACC-117] Virtual Reality Distraction During Awake Deep Brain Stimulation Surgery: A Randomized Crossover Study (Protocol and pilot Trial)

Abdeldayem M, Alberson B, Petersen E. UAMS, Little Rock, Arkansas, United States

Introduction: Deep brain stimulation (DBS) surgery is proven as an effective treatment modality for debilitating movement disorders. Significant pain and stress are endured by patients undergoing this procedure, as the surgery is often performed awake without sedation to allow intra-operative testing of the lesional effect and make adjustments in lead position if necessary. We propose virtual reality (VR) as a novel intra-operative tool for managing pain and anxiety when sedation is contraindicated. Intra-operative VR has been explored for orthopedic surgeries (Chan et al, 2017) and during labor and delivery (Frey et al, 2019).

Methods: 2 Patients undergoing bilateral lead placement were selected as a pilot trial for this study.We used a detachable VR set frame (patent pending). This is a 3D-printed, plastic casing designed to mount onto the Leksell® frame and will encase an Android phone (LG Phoenix 5). We used a commercial software and music (Ocean Rift). The 3D-display ran approximately 10 minutes (±5 min), and could be stopped any time upon the subject’s request.The VR headset was attached to the Leksell frame. For one lead placement procedure, VR was not used. For the other side, VR was used. A scoring questionnaire with values from 1 to 10 – 1 being the worst and 10 being the best – was provided to examine the anxiolytic and analgesic effect of VR. We examined the immersive effect, enjoyment, nausea, and willingness to use VR again in addition to pain relief and anxiolysis.

Results: Current data appears to support a greater anxiolytic rather than pain-relieving effect of VR during awake DBS surgery. Patients report the same pain value with or without VR. Anxiety scores trend lower with the use of VR and though the same pain value is felt, patients report that they spend significantly less time thinking about that pain. All patients surveyed reported enjoyment with VR, willingness to use VR again, and are interested in DBS-specific VR content development.

Conclusions: VR appears to be a useful tool for the functional neurosurgeon during awake DBS lead implantation to provide anxiolysis and distraction from pain while avoiding sedatives that would obfuscate the intra-operative neurologic exam.

[SNACC-118] Wavelet measured cerebral autoregulation and postoperative organ injury following non-cardiac surgery

Highton D*, Saulov K, Barras M, Caney X, Fanning J, Scott I, Sturgess D, White K, Huth S, Kearney A, Oishi S. Princess Alexandra Hospital Southside Clinical Unit University of Queensland, Brisbane, Queensland, Australia*. University of Queensland, Brisbane, Queensland, Australia. Princess Alexandra Hospital, Brisbane, Queensland, Australia

Background: Impaired tissue perfusion during non-cardiac surgery is implicated in end-organ injury, morbidity and mortality. Cerebral autoregulation (CA) describes dynamic vascular changes which maintain end organ perfusion in the brain. The brain represents a unique opportunity to measure intraoperative end-organ hemodynamic function. It has been proposed that combination of hemodynamic compromise and impaired autoregulatory function may contribute to end organ injury, and this has already demonstrated an association between CA and organ injury following cardiac surgery [1]. Non-cardiac surgery presents CA monitoring challenges due to shorter operating length and smaller blood pressure variability. We have previously demonstrated an advanced wavelet signal processing technique which can measure CA from blood pressure and near infrared spectroscopy (NIRS) cerebral oxygenation signals. We hypothesised that wavelet measured CA would differ between patients with postoperative organ injury. The aim of the study was to evaluate differences in CA between patients with perioperative organ injury measured using a wavelet technique.

Methods: Intraoperative monitoring data were analysed from a randomised controlled trial of perioperative angiotensin axis blocker administration. Data were gathered following ethical approval and patient consent. Patients were included for analysis if they received invasive arterial monitoring and cerebral oximetry. Blood pressure and regional cerebral saturation (INVOS 5100C) were downloaded in real time using ICM+ software during surgery. CA was evaluated using wavelet semblance comparing the similarity of fluctuations in blood pressure and cerebral oximetry [2]. Postoperative creatinine was measured daily for 5 days after surgery, and postoperative troponin was measured daily for 3 days after surgery. Kidney injury was defined as a rise of creatinine >26.5 micromol/L, cardiac injury was defined as an elevated high sensitivity troponin >22 ng/L. Wavelet semblance was compared between groups using Student’s t-test.

Results: A total of 53 patients were included in analysis. Mean age 66 (9.8) years, median ASA 3. Mean semblance was 0.24 (0.13) in patients without a kidney injury and 0.35 (0.11) in patients with a kidney injury (P=0.03). Mean semblance was 0.24 (0.14) in patients without cardiac injury and 0.27 (0.11) in patients with a cardiac injury (P=0.45).

Conclusions: There was a significant difference in wavelet measured CA between patients with a perioperative kidney injury, although this did not meet significance for cardiac injury. These results demonstrate the feasibility of wavelet/NIRS measured CA in non-cardiac surgery. Further analysis in larger cohorts is required to define the relationship between CA and hemodynamic targets, medication and patient factors. However this technique has considerable future potential as an intraoperative monitoring technique to define haemodynamic function.

[SNACC-119] Xenobiotics Distribution in Brain Tumor Tissue-A Descriptive Analytical Study

Chowdhury T*, Hasanaly N*, Venkatraghavan L. Toronto, Western Hospital, Toronto, Ontario, Canada*. University of Toronto, Toronto, Ontario, Canada

Introduction: Xenobiotics are foreign chemicals and get detoxified in the body tissues through various metabolic pathways.1 Interestingly, blood brain barrier (BBB) does not allow to cross majority of xenobiotics/metabolites and is considered to be the biggest hurdle in the tumor therapy in Neuro-oncology.2,3 Surprisingly, the presence of xenobiotics, especially anesthetic agents, in brain tumor tissues were never reported in the literature. With the latest advancement in mass spectroscopy techniques, in addition to various metabolites, our team also noted various xenobiotics in the brain tumor tissues. Therefore, this retrospectively study intended to describe various xenobiotics found in brain tumor tissues of patients who underwent resection of brain tumors with or without general anesthesia (GA) [Awake craniotomy (AC)].

Methods: Based on the samples (80 patients: 55 GA, 35 AC) collected during 2005 to 2014, forty two out of sixty four xenobiotics were included. These are related to various metabolism pathways. Out of 42 xenobiotics studied, 9 in GA group and 12 in AC group were included on the basis of normality distribution (skewness of less than 2 and Kurtosis of less than 7).

Results: The mean age for both groups were similar. There were higher grade of tumor (III and IV) in the GA group (96%) as compared with AC group (54%). Most of the xenobiotics in both groups were related to benzoate metabolism (53%), drugs (33%), bacteria/fungal (7%) and xanthine metabolism (7%). Six common xenobiotics were compared. Lidocaine level was found to be significantly higher in the AC group. Interestingly, rocuronium was also found in sample from the GA group (not normally distributed).

Discussion: In this study, multiple xenobiotics were found in brain tumor tissues. The presence of these in brain tumor tissues open the understanding of three major areas: BBB permeability perioperatively, causal association with brain tumor, and altered metabolic pathways. In our analysis, the awake craniotomy group had a higher lidocaine metabolite in the brain tissue sample as compared to those under general anesthesia possible due to the amount of local anesthetic used in awake craniotomy and it demonstrate that brain tumor causes disruption of the blood brain barrier. The presence of rocuronium in subject of craniotomy under general anesthesia may postulate that brain tumor as well as anesthetic agent play a role in increasing blood brain permeability. Whether or not it is a new discovery or a mere finding of unknown significance; future studies are needed to address this (Tables 1–3).

T19
TABLE 1:
Demographic and Tumor characteristics
T20
TABLE 2:
Tumor Xenobiotics Distribution (Based on Normality Distribution
T21
TABLE 3:
Tumor Xenobiotics Common (Based on Normality Distribution) in Both GA and Ac groups
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