A case report of suspected serotonin syndrome following administration of fentanyl

Background: Serotonin syndrome (SS) is a potentially life -threatening drug -induced toxidrome that can occur because of an overdose of a serotoninergic drug or the combination of multiple drugs with serotoninergic activity at therapeutic doses, leading to an increase in serotonergic activity in the central and peripheral nervous system. SS in the setting of general anesthesia is uncommon but possibly underdiagnosed because of the variability in its severity and symptomatology. This report presents a case of severe SS following the administration of fentanyl during induction of general anesthesia. Additionally, it provides a brief overview of the pathophysiology, clinical features, management strategies, and commonly used drugs by anesthesiologists that can potentially result in a fatal interaction. Case Description: This report describes the case of an elderly male patient who was diagnosed with severe SS during video -assisted thoracoscopic surgery (VATS) on the right side. The patient's home medications included sertraline and aripiprazole. During induction of general anesthesia with the administration of fentanyl, the patient became restless and severely hypertensive. He became unresponsive to verbal commands, developed pinpoint pupils, and had myoclonic jerking of his lower extremities. The patient was intubated for airway protection, treated with nitroglycerin, labetalol, and hydralazine for hypertension and underwent neuroimaging. The patient met the Hunter serotonin toxicity criteria for SS. He was treated in the intensive care unit with supportive care and mechanical ventilation, and his sertraline and aripiprazole were discontinued. The patient eventually recovered and was extubated after his neurologic status returned to normal. Conclusions: Clinical features of SS include a spectrum of signs and symptoms related to neuromuscular abnormalities, autonomic hyperactivity, and mental state changes which can be masked under general anesthesia. However, if severe SS occurs, it can be life -threatening and early recognition and prompt treatment are vital to saving the patient's life. This case highlights the importance of considering SS in the differential diagnosis and highlights the need for careful medication management in the perioperative setting.