Exertional Collapse at the Finish Line: Cooling vs. Sedation
A 24-year-old runner collapses 200 m past the finish line of a 10 km road race on a warm, humid morning (WBGT 29°C). He completed the race in 41 minutes. On arrival he is combative and disoriented, pulling at your team. Vitals: HR 148, BP 112/68, RR 26, SpO2 98% on room air, T 40.6°C rectally. Skin is hot and moist; he is sweating profusely. He is not shivering. He cannot answer orientation questions and repeatedly tries to stand. No head strike witnessed, no neck pain. Fingerstick glucose 118 mg/dL. He is being held supine by teammates because he keeps trying to get up.
1. What is the working diagnosis, and how does the presence of profuse sweating and absence of shivering affect your classification?
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Working diagnosis is exertional heat stroke (EHS) - core temperature >40°C plus central nervous system dysfunction in a setting of exertion. The classic absence of sweating is a teaching myth: in exertional heat stroke most athletes are still sweating, because the hypothalamic set point is not reset (unlike classic heat stroke) and cholinergic drive persists until late. Do not use dry skin as a criterion - requiring it delays treatment and kills people.
Key discriminators in this case:
- Core temp >40°C by rectal probe (not oral/temporal/axillary - these lag and are inaccurate in the field).
- CNS dysfunction (combativeness, disorientation) is the defining feature that separates EHS from heat exhaustion.
- No shivering argues against a pure seizure or stimulant toxidrome and is consistent with EHS.
He is not simply 'exhausted' - heat exhaustion patients are typically lucid with normal or near-normal core temperature.
2. He is combative and repeatedly tries to stand. What is your immediate management sequence, and how do you handle the agitation?
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Cool first, transport second. Cold-water immersion is the standard of care for EHS and should begin on site.
- Do not sedate for agitation before cooling is underway. Agitation is a manifestation of the CNS dysfunction of heat stroke and typically resolves as core temperature falls. Chemical sedation (e.g., a benzodiazepine) risks depressing airway and shivering thermogenesis confounds things - but the bigger error is delaying immersion to control behavior.
- Protect the airway and the patient - continuous observation, suction ready, padded immersion tub, enough staff to keep him from climbing out. Do not leave him unattended in water.
- Cold-water immersion (≈1–15°C) with stirring, targeting core temp <39°C - stop active cooling at ~38.5–39°C to avoid overshoot. Typical cooling rates with immersion are ~0.1–0.2°C/min; expect roughly 10–20 minutes.
- Rectal probe continuously during cooling; it is the only valid field measure.
- IV fluids for volume; check glucose (done). Monitor for complications: rhabdomyolysis, AKI, DIC, hepatic injury, arrhythmia.
- Transport to definitive care after cooling is initiated - do not wait for full cooling to load, but do not abandon cooling for transport.
Benzodiazepines are appropriate if agitation persists after cooling or if there is concern for seizure, but never as a substitute for immersion.
3. Two hours later in the ED his core temp is 37.8°C, he is lucid, but his CK is 18,000 U/L and creatinine has risen from 1.0 to 1.4 mg/dL. What is your concern and disposition plan?
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This is the post-cooling phase - the danger has shifted from hyperthermia to organ injury.
- Rhabdomyolysis with CK 18,000 and a rising creatinine suggests acute kidney injury from myoglobinuria plus hypovolemia. Aggressive isotonic IV fluids targeting urine output ~200–300 mL/h (or ~1–2 mL/kg/h) are the mainstay; alkalinization is not proven and not routine.
- Hepatic injury (transaminases can peak at 24–72 h) and coagulopathy/DIC must be monitored; check LFTs, platelets, PT/INR, fibrinogen.
- Cardiac - troponin and ECG; arrhythmias and myocardial injury occur.
- Do not discharge based on normalized temperature and lucidity. Admit for observation and serial labs. EHS carries meaningful mortality and multi-organ sequelae even after the patient 'looks fine.'
- Counsel on return to activity: no training until labs normalize and a graduated heat-acclimatization plan is in place; recurrence risk is real and prevention (acclimatization, hydration, pacing, event medical planning) is the focus.