Heat stroke — USMLE Step 2 CK MCQ

Correct answer: D — Begin immediate whole-body cold-water immersion while arranging emergency transport

Altered mental status plus marked core hyperthermia during exertion is exertional heat stroke, a time-critical emergency. Immediate rapid cooling should begin at the scene while emergency transport is arranged; cooling must not wait for laboratory results or hospital arrival. When feasible, attended whole-body cold-water immersion provides the fastest conductive cooling. Airway and circulation are supported concurrently, rectal temperature is monitored, and immersion is stopped near the target range to avoid overshoot. Antipyretics do not help because heat stroke is not caused by an elevated hypothalamic set point and may add hepatic toxicity. Dantrolene is used for malignant hyperthermia and selected hypermetabolic syndromes, not routine exertional heat stroke. Laboratory evaluation for renal injury, electrolyte disturbance, rhabdomyolysis, hepatic injury, and coagulopathy is important but follows initiation of lifesaving cooling.

Reference: Centers for Disease Control and Prevention. Yellow Book: Heat and Cold Illness in Travelers. https://www.cdc.gov/yellow-book/hcp/environmental-hazards-risks/heat-and-cold-illness-in-travelers.html