Takeaways
Question: What is the incidence and outcome of critical events during pediatric craniofacial surgery at a single high-volume center?
Findings: This study reviewed 2072 major craniofacial procedures (transcranial, mixed transcranial and extracranial, or major extracranial facial osteotomies). Critical events occurred in 14 cases (0.67%): venous air embolism, n = 4; cardiac complications, n = 3; major hemorrhage, n = 3; trigeminocardiac reflex, n = 2; acute intracranial hypertension, n = 1; and airway obstruction, n = 1. There were no mortalities or permanent morbidities.
Meaning: Critical events during pediatric craniofacial surgery are, fortunately, rare. Experienced teams are essential in managing critical and catastrophic intraoperative events.
INTRODUCTION
Pediatric craniofacial surgery has evolved since its inception with a high level of safety and predictable outcomes. The management of children with craniofacial conditions has benefited from technological advancements in radiographic imaging, hypotensive anesthesia, three-dimensional (3D) bone fixation systems, application of molecular genetics, introduction of new surgical techniques such as bone distraction, and an improved understanding of the natural history of long-term outcomes. The role of an experienced multidisciplinary team is essential. Historically, a mortality rate between 1.3% and 1.6% has been reported.1,2 The improved safety profile in the management of complex pediatric craniofacial conditions was emphasized in a study reporting the experience from two pediatric craniofacial centers with a total of 8101 major craniofacial procedures (7328 intracranial and 773 subcranial procedures) over an 18-year period.3 The combined intracranial major morbidity rate was less than 0.1%, and the combined mortality rate was 0.1%. There were nine mortalities during this period demonstrating that even in experienced centers with dedicated teams, catastrophic events may occur.
While major morbidity and mortality rates of complex pediatric craniofacial procedures have improved, the inherent risk in the management of these cases is not negligible. Parents routinely inquire as to the risks of surgery for their children. While the ensuing conversation focuses on standard concerns, such as bleeding, infection, scars, etc., it is important to be inclusive of potentially life-threatening events such as venous air embolism and major hemorrhage. The aim of this study was to review the incidence and outcomes of catastrophic and critical events occurring during surgery at a single high-volume pediatric craniofacial center.
METHODS
The Hospital for Sick Children at the University of Toronto has a high volume of pediatric craniofacial surgery performed by experienced craniofacial surgeons. Data were retrospectively reviewed from our institutional database and medical records. Following research ethics board approval, all craniofacial surgical cases performed by two senior pediatric craniofacial surgeons between January 2002 and January 2019 were reviewed. Inclusion criteria included children undergoing a major craniofacial surgery, defined as transcranial, mixed trans-and-extracranial, or major extracranial facial osteotomies. The intraoperative code episodes were identified as an event initiating a code response and actioning emergency management. The operative details and outcome data were retrieved and reviewed. Data were summarized with means and standard deviations or medians for the continuous data and with frequencies for the categorical data. A Fisher exact test was used to assess the relationship between cardiac arrest and a diagnosis of craniosynostosis. The relationship between cardiac arrest and length of stay was evaluated using an unpaired t test. The level of statistical significance was 0.05.
RESULTS
There were 7214 procedures performed in the study period by the two senior surgeons. Of these, 2072 (29%) cases were categorized as major craniofacial procedures. A code event was initiated in 14 procedures (0.67% of major craniofacial procedures; 11 male patients, three female patients; median age 1.2 years, range 4 months to 21 years). Eleven patients were undergoing surgery to correct craniosynostosis (nine single suture and two multisuture). Twelve patients were undergoing intracranial procedures, and two were undergoing subcranial orthognathic surgery. The causes for code initiation included major bleeding (n = 3), venous air embolism (n = 4), cardiac issues (n = 3) (heart block, depressed cardiac output due to tetrology of Fallot, and rapid blood transfusion), acute intracranial hypertension (n = 1), acute airway obstruction (n = 1), and severe trigeminocardiac reflex (n = 2). (See figure, Supplemental Digital Content 1, which shows patient cases, https://links.lww.com/PRSGO/C364). Cardiac arrest requiring compressions and/or defibrillation was necessary for eight patients. Two patients (14%) in our series experienced a critical event that was anesthesia-related (severe laryngospasm and mucous plug occluding a nasotracheal tube). Surgery was successfully completed in seven patients and curtailed in seven patients. There were no mortalities in this series. There was no statistical difference in the occurrence of cardiac arrest in patients with synostosis compared with all other diagnoses (P = 0.56). The mean length of hospital stay was 4.6 ± 3.4 days. There was a significantly longer length of stay (P = 0.03) in patients who had a cardiac arrest (6.6 ± 3.7 days) compared with those with no cardiac arrest (2.7 ± 1.7 days).
Illustrative Case Presentation
An 8-month-old infant (8.6 kg) with left coronal and sagittal synostosis presented with no papilledema and substantial cranial dysmorphism (Fig. 1). Preoperative investigations included low-dose bone-only CT, and MRI with venous assessment (Figs. 2, 3). A total cranial vault reshaping was planned. The patient underwent a nasotracheal intubation, had two intravenous lines, an arterial line, and Foley catheter and was placed in the prone position to perform the posterior portion of the cranial vault reshaping (posterior to the coronal sutures). After elevation of the coronal flap, both parietal and the sagittal components of the vault were removed with no hemodynamic compromise. During the separation of the dura from the overlying bone, significant bleeding was encountered, and the mean arterial blood pressure dropped into the 30s leading to the procedure being halted for catch-up transfusion. Anesthesia notified the surgeon about the continuing drop in mean arterial blood pressure with subsequent asystolic cardiac arrest (Fig. 4). The scalp was stapled and patient turned into the supine position, and compressions were started for a period of 8 minutes. An unfavorable cardiac rhythm (torsades de pointes and pulseless electrical activity) was noted, and the patient was defibrillated and satisfactory rhythm was restored with output. A massive transfusion protocol was initiated to manage the blood loss and secondary major coagulopathy. The mother was notified about the event following restoration of cardiac output. The patient received seven units (U) of packed red blood cells, eight U cryoprecipitate, four U platelets, three U fresh frozen plasma, activated factor 7, and vitamin K and remained in the operating room (OR) for 3 hours to correct the coagulopathy before being transferred to the intensive care unit. The infant maintained hemodynamic stability and was intact neurologically. He was returned to the OR on postoperative day (POD) 3 for a washout and evacuation of a large subgaleal hematoma and definitive scalp closure. On POD 5, he had a grand mal seizure. A computed tomography (CT) and magnetic resonant imaging (MRI) demonstrated venous infarctions in multiple areas (posterior left temporal lobe, left frontal lobe, and right parieto-occipital lobe). He was started on antiseizure medication and was discharged home on POD 14. Five months after his first surgery at 13 months of age, he underwent anterior cranio-orbital reshaping for correction of residual anterior plagiocephaly. He was seen in clinic at 3.6 years of age and is seizure-free, taking no medications and neurodevelopmentally appropriate with mild residual cranial dysmorphism (Fig. 4).
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Fig. 1.: Patient in the OR in preparation for total cranial vault reshaping (A-D).
Fig. 2.: Preoperative CT scan demonstrating left coronal and sagittal synostosis (A-E). Note the presence of numerous Wormian bones in the lambdoid sutures that increase the number of adhesion points necessary to release during dural dissection from the bone.
Fig. 3.: Preoperative MRI scan with venous study demonstrating a large emissary vein over the vertex of the skull.
Fig. 4.: Patient in clinic 2.5 years postoperative with mild residual cranial dysmorphism but neurologically and developmentally appropriate and seizure-free (A-C).
A review of this case indicated the following: (1) MRI venous studies do not provide the same degree of image resolution as CT venograms, and the large emissary vein in the vertex was not appreciated as it should have been; (2) a number of Wormian bones increased the number of adhesion points, making dissection of the dura from the bone more technically difficult, which resulted in a longer dissection time and allowed for prolonged bleeding; and (3) hemovolemic shock and possibly a venous air embolism resulted in an asystolic cardiac arrest.
DISCUSSION
There are several recently published studies detailing complications following pediatric craniosynostosis surgery.4–8 In 2017, the Pediatric Craniofacial Surgery Perioperative Registry assessed 1223 cases from 31 institutions across the United States from June 2012 to September 2015 and presented a comprehensive overview of the perioperative management, outcomes, and intraoperative complications, which included cardiac arrest (0.2%), hypotension (5.3%), bradycardia requiring treatment (1.6%), suspected venous air embolism (1.1%), and large-volume (>40 mL/kg) blood transfusion (26.8.1%) but no deaths.8 This study highlighted the large variability in perioperative management and outcomes and opportunities for improvement. A follow-up study from the same Pediatric Craniofacial Collaborative Group analyzed 1814 patients from 33 centers and demonstrated a 15% incidence of major perioperative complications following pediatric cranial vault reconstruction.7 Multivariable predictors included ASA status III or IV, syndrome, nonusage of antifibrinolytics, blood product transfusion of more than 50 mL/kg, and surgical duration over 5 hours. No deaths were reported. There were no details of specific life-threatening or catastrophic events in this study. The importance of high patient volume (>40 cases per year) in significantly decreasing the complication risks was highlighted in a large multicenter patient series (13,112 patients from 49 centers between 2004 and 2015) with a 10.7% complication rate in high-volume centers compared with 13.7% in low-volume centers. However, the specific details about life-threatening and catastrophic events were not reported.6
Our study assessed the occurrence of life-threatening and catastrophic events during the surgical treatment of patients with complex craniofacial conditions at a single high-volume pediatric craniofacial unit. Fortunately, these events were rare, occurring in 0.67% of cases (one case in 148 major craniofacial procedures) despite being a high-volume and experienced unit. No mortalities were incurred as the result of surgical treatment, but one patient died from unrelated causes (cardiac) 6 years after surgery.
Preoperative discussion and obtaining consent involve a review of the relevant risks related to the general anesthetic and to the surgical procedure itself. Although the risks associated with a general anesthetic in infants and children are relatively small, the Anaesthesia Practice In Children Observational Trial (APRICOT) study assessed 31,127 anesthetic procedures in 30,874 children (mean age 6.35 years) in 261 centers across 33 European countries (April 2014 and January 2015) and demonstrated that the occurrence of perioperative severe critical events requiring immediate intervention was 5.2% with an incidence of respiratory critical events of 3.1%.9 Our study showed that the occurrence of these events was lower at our institution and may reflect the highly specialized nature of the clinical work done at a dedicated pediatric center. Specific to pediatric craniofacial patients, concerns have been raised regarding the impact of a general anesthetic on the neurodevelopment of the infant brain. However, several reviews have demonstrated that although general anesthetics have the potential to induce neurotoxicity, there was limited clinical evidence to support alteration in neurodevelopmental outcome.10,11 Perioperative respiratory adverse events (laryngospasm and bronchospasm) are not uncommon in infants and children occurring in up to 5.4% of cases.12 One patient in our series experienced substantial laryngospasm that almost necessitated a tracheostomy but was fortunately intubated, and the surgery was completed. One other child undergoing posterior cranial vault reshaping experienced an anesthetic-related complication (mucous plug in a prone position resulting in inability to ventilate) that prevented successful completion of the surgery. In our series, two of 14 cases (14%) experienced an anesthesia-related critical event.
Cranial vault remodeling surgery includes blood loss and the need for administration of blood products. Blood conservation techniques are used, including hypotensive anesthesia, antifibrinolytics (tranexamic acid), tumescent infiltration, preoperative administration of oral iron, cautery for dissection, use of fibrin sealants and hemostatic agents, acute hypervolemic hemodilution, and targeted blood transfusion. In our practice, cell savers are not routinely used. Two large-bore intravenous lines and arterial lines are used during infant craniosynostosis surgery, but central lines are not routinely used. Visualization of the patient’s monitor by the surgical team is useful to simultaneously observe the metrics and vital signs throughout the case. Our transfusion rate is approximately 75% in infants undergoing single suture synostosis surgery, and the majority (95%) of cases receiving blood products are exposed to only one donor unit.
For the experienced craniofacial team, bleeding and volume management remain one of the major challenges in pediatric craniofacial surgery. Studies have demonstrated that the actual calculated blood loss during surgery is greater than estimated blood loss by the surgical team.13 Visual estimation of blood loss is particularly inaccurate.14 Having an experienced anesthesia team is an essential component to successful fluid and volume management. The triggers for transfusion of blood products include a hemoglobin less than 7/0 g/dL, abnormal coagulation parameters, obvious ongoing blood loss and abnormal vital signs but often the decision to transfuse may be subjective and influenced by experience.
In our study, hypovolemia leading to cardiac arrest occurred in three patients due to dural venous sinus injury during dissection of the dura from the endocranial surface of the bone in the posterior cranial vault with the patient in the prone position. Two of these cases required immediate closure of the incision and rapid transfer to a supine position with initiation of cardiac compressions. The surgical decision-making challenge includes whether to complete the dissection and remove the bone to visualize and control the site of bleeding or to manage conservatively with pressure on the bone flap. One case resulted in initiation of the massive transfusion protocol, which provided advantages of dedicated resources to manage the patient’s hemorrhage and subsequent coagulopathy.15 Preoperative imaging of the venous anatomy in children with syndromic and multisuture craniosynostosis is mandated in all cases of posterior cranial vault reshaping. As the result of these cases of disruption of the dural venous sinuses, CT venogram provides better imaging of the anatomy compared with MRI and is now included in our standard protocol for these patients (Fig. 1).
Venous air embolism is a risk in pediatric craniofacial surgery occurring in up to 2.6% of cases.16 However, evaluation using a precordial Doppler ultrasonic probe detected venous air embolism events in 82.6% of children undergoing craniectomy for craniosynostosis indicating that this is a common occurrence but fortunately it is rarely associated with cardiovascular collapse.17 Predisposing factors to venous air embolism include the large surgical surface area, the presence of a pressure gradient between the low-pressure veins on the dura and in the bone often exacerbated by a head-up position (as little as 5 cm), the potential for rapid blood loss, and hypotension leading to a decrease in central venous pressure enhancing the pressure gradient between the right atrium and surgical site.18 Hypotension with venous air embolism may be more pronounced in children because the volume of entrained air is greater in comparison to their cardiac volume. Furthermore, the persistence of a patent foramen ovale in 50% of children under 5 years of age may increase the potential for paradoxic air embolism. Monitoring practices include end-tidal nitrogen concentration, end-tidal carbon dioxide concentration, transcutaneous oxygen saturation, central venous pressure monitoring, and esophageal stethoscope monitoring, but the most sensitive indicators are transesophageal echocardiogram and the precordial Doppler probe.
The diagnosis of venous gas embolism is predominately clinical and requires a high level of suspicion. In three of four cases in our series, the venous air embolism events were associated with bleeding and presented with sudden onset of hypotension, reduced cardiac output and loss of EtCO2. One event occurred during scalp closure with the placement of two drains attached to high continuous suction, suggesting a Venturi effect with air being pulled into the low-pressure venous system. Treatment of venous gas embolism is largely supportive and involves preventing entry of additional air into the venous system by flooding the field with saline, eliminating the pressure gradient, positioning the patient in left lateral decubitus position, and allowing for appropriate resuscitative measures to proceed. Cardiac compressions may help to break up large air bubbles. Avoiding the use of nitrous oxide as an anesthetic agent is also recommended as nitrous oxide causes expansion of any intravascular air bubbles.
Two patients in our series experienced a severe trigeminocardiac reflex with asystole during orthognathic surgery. One occurred during the Le Fort I maxillary down-fracture, and the second occurred after completion of the bilateral sagittal split mandibular osteotomy as the mandible was being manipulated into the dental splint. Coincidentally, both patients had juvenile idiopathic arthritis that was not considered to be a contributing factor. The trigeminocardiac reflex was first described by Shelly and Church19 in 1988 and is presently defined as a decreased heart rate and mean arterial pressure of greater than or equal to 20% on surgical manipulation in the vicinity of any trigeminal nerve branch. Orthognathic surgery has a trigeminocardiac reflex incidence of 9.1%.20 The most important trigger of the reflex includes sudden mechanical stretch of the trigeminal nerve. Most cases of asystole secondary to trigeminocardiac reflex have been reported in neurosurgery or ophthalmic surgery, but our cases confirm previous reports in orthognathic surgery.21 A mandibular nerve block and careful surgical technique in the distribution of the trigeminal nerve have been suggested to decrease the risk of trigeminocardiac reflex. Treatment includes discontinuation of the inciting stimulus and the use of vagolytic agents and/or epinephrine.
Lessons learned from these critical events focus on the importance of an orderly and rapid escalation of activity emphasizing communication and safety to ensure a satisfactory outcome for the patient. (See figure, Supplemental Digital Content 2, which shows lessons learned, https://links.lww.com/PRSGO/C365). Important points include immediate notification of the operative team, recruitment of the resuscitation team, wound closure, protection of any biologic materials and sterile instruments, and positioning of the patient to afford successful resuscitation. Documentation during the event, initiation of the massive transfusion protocol as needed, notification of the family when appropriate, and early and delayed postevent debriefing with the team are also important points. During the preoperative huddle, a discussion of possible concerns is useful preparation in the event of a critical occurrence. Finally, simulation training exercises have been demonstrated to be effective in improving communication and skills of the team members.
Limitations of this study include the retrospective study design and analysis of the data. This study included assessment of the events that occurred during major craniofacial procedures and did not include “near-misses.” As such, the true incidence of potentially critical and catastrophic events may have been unintentionally underreported. Data on posttreatment complications have not been captured in this study.
CONCLUSIONS
Despite operating in a tertiary care pediatric center with senior experienced surgeons, critical intraoperative events can occur, and successful outcomes are dependent on awareness, experience, communication, and a multidisciplinary team approach. This series provides a review of the risk profile in major craniofacial surgery and lends a platform to reflect on possible catastrophic outcomes of these operations.
PATIENT CONSENT STATEMENT
The patient provided written consent for the use of his image.
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