Neuraxial Anesthesia for a Lower Extremity Biopsy on a Patient Younger Than 55 Weeks Post-Conceptual Age

Abstract

Introduction: Postoperative apnea is a major concern with surgery in neonates. Postoperative apnea can be defined as respiratory pauses of more than 15 seconds that can be associated with bradycardia, desaturation, cyanosis or hypotonia. Risk factors for postoperative apnea in neonates include prematurity, congenital anomalies, history of apnea and bradycardia, anemia, and lung disease. Another significant risk factor is post-conceptual age less than 46-60 weeks at time of surgery. Postoperative apnea affects 10% of infants under 60 weeks of post-conceptual age. The younger the patient’s gestational and post-conceptual ages, the greater the risk for postoperative apnea. (1) Some studies suggest that neonates that receive general anesthetics experience more respiratory complications as opposed to those who do not. Immature liver elimination and harsh adverse reactions of general anesthetics likely play a large role in postoperative apnea. As a result, infants at high risk for development of postoperative apnea may benefit from a regional anesthetic instead. (2) Case Description: A 42-week post-conceptual age female who was born at term without complications presented to orthopedics for a right foot mass. An MRI revealed a large, vascularized subcutaneous mass located on the dorsum of the right foot. The differential diagnosis included vascular malformation and infantile fibrosarcoma. The patient was referred to plastic surgery and interventional radiology for a biopsy of the mass two weeks later. Neuraxial anesthesia was preferred for this operation to reduce the risk of postoperative apnea that could arise from general anesthesia. The procedure was discussed with the patient’s family and their consent was obtained for both general and regional anesthesia. A 25-gauge spinal needle was used to inject 4mg of bupivacaine via a midline approach in the L4-L5 interspace. The patient was then supervised using standard ASA monitors. Her vital signs remained stable throughout the biopsy. The patient was then transferred to the post-anesthesia care unit where she was able to move all extremities and produce urine. She was discharged from the hospital later that day. Pathology later identified the mass as a rapidly involuting congenital hemangioma. Discussion: Postoperative apnea poses a significant risk to the neonate after a general anesthetic. Specific ages regarding postoperative apnea monitoring vary by institution. At our institution, neonates up to fifty-five weeks of post conceptual age are monitored for at least eight hours after a general anesthetic. A spinal block was performed on a 44-week post-conceptual age female prior to a foot mass biopsy. The patient was comfortable after the operation and avoided an inpatient stay that would have been required had she undergone general anesthesia. Measures to avoid an overnight hospital stay should be considered as they can reduce the cost of care for families and improve resource management for hospitals. This is especially pressing for healthcare institutions during the COVID-19 pandemic when resources are inherently limited. Conclusion: A neuraxial approach versus general anesthesia is a viable option for a patient receiving a lower extremity biopsy procedure at <55 weeks post-conceptual age. References:

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