Serious adverse effect of low-dose dexmedetomidine under spinal anesthesia: A case report and literature review

Dexmedetomidine is a highly selective α_2-adrenergic agonist with sedo-analgesic properties. It has been approved by the United States Food and Drug Administration (FDA) for sedation of critically ill patients, facilitation of awake procedures, and management of patient agitation. However, its use has been occasionally associated with adverse effects like bradycardia, hypotension, and asystole. The risk of these effects, particularly cardiac arrest, is increased in the elderly, patients with multiple comorbidities, and administration of higher doses of the drug (especially loading doses). However, perioperative pericardiac arrest with only low-dose dexmedetomidine infusion, in a young healthy male, has not been previously reported.Case Presentation: We report a 33-year-old male, ASA 1 E, who underwent open reduction and internal fixation of a left ankle fracture under spinal anesthesia. He was sedated intraoperatively with intravenous dexmedetomidine, infused at 0.2 μg/kg/h, without a loading dose. Approximately 90 minutes into the procedure, he had severe bradycardia and hypotension, leading to a peri-arrest situation. He was successfully revived with intravenous atropine and ephedrine and completed the surgery uneventfully.

We opine that the use of dexmedetomidine as a sedative agent in patients under spinal anesthesia requires heightened caution due to the risk of major adverse cardiac events. Our case exemplifies that this risk persists even in healthy young patients, at low drug infusion rates, and even after avoiding a loading dose.