The children’s parents provided written permission for publication of the report. Awake spinal anesthesia technique for young infants is well described in the literature. Spinal anesthesia has the desirable properties of decreasing or avoiding exposure to general anesthesia which can be associated with apnea, laryngospasm, hemodynamic changes, and potential neurotoxicity in the developing infant brain.1–3 Despite adequate sensory and motor block from the spinal anesthesia, infants may move their head, arms, and torso and interrupt surgery, necessitating the addition of sedatives or general anesthesia. In addition, sedatives are associated with unwanted hemodynamic changes, apnea, and potential neurotoxicity in infants.1–3
Dexmedetomidine is an alpha-2 agonist and the only sedative devoid of neurotoxic effects in animal models. When used as a sedative, it preserves spontaneous respiration and produces analgesia and anxiolysis.4,5 Adverse effects include hypotension, hypertension, bradycardia, and heart block in both adult and pediatric patients. When used as the sole sedative for infants and young children, dexmedetomidine was associated with >20% decreases in blood pressure and heart rate in 0% to 25% and 4% to 25% of patients, respectively.6–8
The use of intranasal or intravenous dexmedetomidine in combination with infant spinal anesthesia has not been reported. Although spinal anesthesia alone rarely causes hemodynamic changes in infants, the impact of the combination with dexmedetomidine is unclear. This report illustrates the effects of combining dexmedetomidine for sedation with spinal anesthesia in 3 infants. For purposes of this report, decreases in mean arterial blood pressure (MAP) or heart rate of 20% or more were considered clinically relevant.
In all 3 cases, similar techniques were used to induce the spinal anesthetic. Standard monitors were utilized. A nasal cannula and electrocardiographic leads were used to monitor end-tidal carbon dioxide concentration and respiratory rate. A spinal anesthetic was administered in sterile fashion with the patient in either the sitting or the lateral decubitus position. A 22-gauge 3.8-cm Quincke needle (BD Medical, Franklin Lakes, NJ) was placed in either the L4–L5 or L5–S1 interspace with aspiration of clear cerebrospinal fluid followed by injection of bupivacaine.
The first patient was a 1-month-old infant scheduled for right inguinal hernia repair. A 24-gauge intravenous catheter was placed in the awake infant and dexmedetomidine was then started at 2 μg/kg/h. Spinal anesthesia was induced by intrathecal injection of 1 mg/kg of isobaric bupivacaine 0.5%. Heart rate reached the preoperative level of approximately 120 beats/min, and MAP ranged from 44 to 54 mm Hg near its preoperative level of 50 mm Hg. Surgery was completed in 45 minutes with no additional medications required. During a 30-hour postoperative period, heart rate ranged from 105 to 140 beats/min, no apneic episodes were observed, and the Face, Legs, Activity, Cry, Consolability (FLACC) score was always zero.
The second patient was a 2-month-old infant, who was also scheduled for a right inguinal hernia repair. For the placement of a 24-gauge intravenous catheter, anesthesia was induced by inhalation of sevoflurane via facemask. Sevoflurane was then discontinued. Spinal anesthesia was administered using 0.9 mg/kg isobaric bupivacaine 0.5%. Subsequently, a 1 μg/kg infusion of dexmedetomidine was intravenously administered over 10 minutes followed by a continuous infusion at 1 μg/kg/h. Blood pressure and heart rate decreased maximally by 10%. Respiratory rate ranged from 20 to 51 breaths/min with no apneic episodes. Surgery was completed successfully in 45 minutes with no additional sedation required. During the 2.5-hour recovery room stay, heart rate decreased maximally by 7%, respiratory rate ranged from 36 to 40 breaths/min without apneic episodes, and FLACC scores (determined at 15-minute intervals) were zero. Follow-up phone call to the parents on postoperative day 1 revealed no adverse events.
The third patient was a 9-month-old infant with phimosis, who was scheduled for a circumcision. Spinal anesthesia was chosen to accommodate parental request to avoid general anesthesia. Two micrograms per kilogram of dexmedetomidine were given intranasally to facilitate placement of a 24-gauge intravenous catheter. Spinal anesthesia was administered with 0.7 mg/kg of hyperbaric bupivacaine 0.75%. There was no clinically relevant change in heart rate or MAP. Surgery was completed in 19 minutes with no additional medications required. During the 3-hour recovery room period, heart rate ranged from 101 to 128 beats/min, respiratory rate ranged from 28 to 40 breaths/min with no apneic episodes, and FLACC scores were zero measured every 15 minutes.
To the best of our knowledge, we report for the first time a novel use of modest doses of dexmedetomidine as a supplemental sedative for spinal anesthesia in infants (defined as age <2 years) during spinal anesthesia. None of the infants experienced clinically relevant hemodynamic changes or apneic episodes. Peripheral oxygen saturation was always 100% without the need to supplemental oxygen administration. Surgeries could be safely performed without the need for conversion to general anesthesia.
McVey and Tobias9 administered dexmedetomidine (bolus dose of 1 µg/kg bolus followed by continuous infusion of 1–2 µg/kg/h) in combination with ketamine (bolus dose of 2 mg/kg followed by intermittent bolus doses of 0.5 mg/kg as needed) for sedation during spinal anesthesia in infants and children between the ages of 2 and 9 years. Heart rate changes of >20% occurred in 5 of 12 patients, and systolic blood pressure changes >20% occurred in 1 of 12 patients. Our infants did not exhibit clinically relevant changes in heart rate or blood pressure.
The avoidance of hemodynamic changes may be especially valuable in infants. A report by McCann et al10 implicates hypotension as a potential cause of encephalopathy and seizures following standard surgeries with general anesthesia in a series of infants. After reviewing our cases, we feel it may be possible to have successful and safe sedation with dexmedetomidine during spinal anesthesia while preserving hemodynamic stability. This sedation may also help to reduce the up to 19% intraoperative conversion from spinal anesthesia to general anesthesia in infants undergoing inguinal hernia surgery under spinal anesthesia.11 A prospective randomized trial of patients will help further assess hemodynamic changes, and we hope our experience encourages such study.
Other benefits of dexmedetomidine include preservation of airway function and respiratory drive. Our children had no perioperative hypoxemic or apneic episodes. However, larger numbers of patients are needed to confirm the safety of this technique.
Alpha-2 adrenoceptor agonists have analgesic and anxiolytic effects. In our children, the postoperative FLACC scores were zero even after the spinal anesthetic had worn off and motor function returned. Intravenous dexmedetomidine may exhibit synergistic effects with regional anesthetic techniques.12 Of possible clinical relevance, dexmedetomidine exhibited neuroprotective effects in various in vitro and in vivo laboratory studies.13
In conclusion, the use of dexmedetomidine as a supplemental sedative to infant spinal anesthesia may provide many benefits for patients, anesthesiologists, and surgeons. It decreases infant movement under the drapes, thereby increasing safety and facilitating surgery. It also lowers the risk of conversion to general anesthesia intraoperatively. Conversion under these circumstances presents its own challenges. We feel this technique is worthy of further investigation and clinical trials.
Name: Franklin Chiao, MD, MS.
Contribution: This author helped research, and write and review the manuscript.
Name: Karen Boretsky, MD.
Contribution: This author helped research, and edit and review the manuscript.
This manuscript was handled by: Hans-Joachim Priebe, MD, FRCA, FCAI.
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