Cholinergic urticaria following active forced-air warming in the post-anesthesia care unit: a case report and...

Cholinergic urticaria (CU), a subtype of chronic inducible urticaria, is triggered by elevations in core body temperature. Postoperative shivering and active warming measures may increase core body temperature in the post-anesthesia care unit (PACU), yet CU in this setting remains underrecognized and has rarely been reported.

We report a case of an 18-year-old male who developed acute CU in the PACU following cochlear implantation under general anesthesia. After extubation, the patient exhibited postoperative shivering and was treated with a forced-air warming blanket. Approximately 10 min later, he developed diffuse punctate wheals with pale centers and peripheral erythematous halos across the trunk, accompanied by severe pruritus and tachycardia (110-126 beats/min). Given the patient's history of exercise- and heat-induced eruptions, together with stable hemodynamics and the absence of respiratory distress, the clinical findings were considered more consistent with cholinergic urticaria than with severe perioperative hypersensitivity.

Immediate cessation of active warming, intravenous diphenhydramine (20 mg), and environmental cooling resulted in rapid symptom relief within 20 min.

This case underscores the synergistic pathophysiology of postoperative shivering, active warming, and extubation-related sympathetic activation in precipitating CU. This case suggests that postoperative shivering, active warming, and extubation-related sympathetic activation occurred in close temporal sequence with the CU episode and may have jointly contributed to the rapid rise in core temperature and symptom onset. CU may occur during post-anesthesia recovery and should be promptly recognized on the basis of rash morphology, vital signs, and dynamic body temperature changes, differentiated from perioperative anaphylaxis, and managed with targeted temperature control and symptomatic treatment.