Harrison's PodClass: Internal Medicine Cases and Board Prep Ep 140: A 45-Year-Old Man with Confusion After Running
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Apr 3, 2025 A 45-year-old runner collapses with severe hyperthermia and confusion. Discussion covers heat regulation, evaporation, and how humidity and clothing impair cooling. They contrast exertional versus classic heat stroke and list multisystem complications. Rapid cooling strategies and when advanced care or liver transplant may be needed are also highlighted.
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Runner Collapses With Exertional Heat Stroke
- A 45-year-old healthy frequent runner collapsed two hours after a seven-mile run on a hot, humid August day with core temperature 42.5°C and confusion.
- EMS found tachycardia, tachypnea, mild hypotension and intact oxygenation, prompting ICU admission for suspected exertional heat stroke.
Evaporation Drives Heat Loss And Fails In Humidity
- Sweating (evaporative cooling) is the most efficient heat-loss mechanism but fails as relative humidity rises above ~70%.
- High humidity, occlusive clothing, dripping sweat, and volume depletion markedly increase heat illness risk.
Exertional Heat Stroke Presents Differently Than Classic
- Exertional heat stroke occurs in young healthy people (athletes, laborers) and often presents with profuse sweating despite severe dehydration.
- This contrasts with classic heat stroke where patients — often elderly — have hot dry skin and ceased sweating.
