Collapse at the Finish Line of a Summer Half-Marathon
A 24-year-old recreational runner collapses 20 m past the finish line of a half-marathon started at 8:00 AM on a day with a heat index of 95°F (35°C) and 70% humidity. On-field staff find him confused, combative, and unable to answer questions. Rectal temperature is 104.9°F (40.5°C). Heart rate 132, BP 96/54, respirations 28. Skin is hot and dry; he has not urinated since before the race. He drank roughly 4 L of water during the race and took no salt tablets. He was last seen well at mile 10. Ambient cooling supplies on site: ice bags, cold wet towels, a kiddie pool, and a fan; no immersion tub. EMS is 12 minutes out.
1. What is your leading diagnosis and immediate management priority, and how do you justify it against the main alternative?
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Leading diagnosis: exertional heat stroke (EHS). Core temperature >104°F with CNS dysfunction (confusion, combativeness) in a hot environment meets the classic triad; the dry skin is not reassuring either way because athletes can be sweating or not.
Main alternative to exclude: exertional hyponatremia. He drank ~4 L of plain water without sodium over a long race, which is a classic setup. However, hyponatremic encephalopathy usually produces temperatures near normal or only mildly elevated, and a rectal temp of 40.5°C strongly favors EHS. Importantly, the two are not mutually exclusive - check a point-of-care sodium if available, but do not delay cooling to do so.
Immediate priority: rapid cooling. The mortality of EHS is driven by time above the critical thermal threshold ("cool first, transport second"). Target cooling rate >0.15°C/min and goal core temp ~38–39°C. With no tub, the best available option is cold-water immersion in the kiddie pool with ice added, or if the pool cannot accommodate him, aggressive ice-towel rotation over the whole body with fanning plus ice packs to the neck, axillae, and groin. Antipyretics (acetaminophen, NSAIDs) are ineffective in EHS and hepatotoxic/renal-toxic risk - do not use. Do not give IV fluids as a substitute for cooling; start isotonic fluids for hypotension but cooling is the intervention that changes outcome. Recheck rectal temperature every 5–10 minutes and stop active cooling at ~38.5°C to avoid overshoot. Transport to a facility capable of managing rhabdomyolysis, AKI, DIC, and hepatic injury.
2. Twelve minutes later he is cooled to 38.6°C, is now conversant, and asks to go home. What is your disposition and monitoring plan, and what findings would change it?
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Do not discharge from the field. Even after successful cooling, EHS carries a substantial risk of a delayed multi-organ cascade over the next 24–72 hours: rhabdomyolysis and acute kidney injury, hepatic injury (often peaking at 24–72 h), coagulopathy/DIC, and myocardial injury. He also has a plausible concurrent hyponatremia and has not urinated.
Transport to the ED for:
- CBC, comprehensive metabolic panel, creatine kinase, PT/INR, fibrinogen, urinalysis (myoglobinuria), troponin, and serum sodium (to address the water-loading history).
- Continuous cardiac monitoring and serial neuro checks.
- IV isotonic fluids titrated to urine output; monitor for AKI.
Findings that would escalate care: CK >5,000 U/L or rising, rising creatinine, transaminases climbing at 24–48 h, falling platelets or prolonged INR, altered mentation recurring, or any arrhythmia. Recurrent hyperthermia after cooling can indicate a non–heat-illness cause (e.g., stimulant use, serotonin syndrome, malignant hyperthermia susceptibility) and warrants a broader workup.
Return-to-play counseling: no running for at least a week, gradual reacclimatization over 2–4 weeks, hydration/sodium strategy education, and no return until labs normalize. He should be counseled that prior EHS increases risk and that acclimatization and pacing (not water loading) are the protective measures.