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Heat illness and heat stroke
Heat stroke is a core temperature of 40 °C or more with central nervous system dysfunction; it is an emergency in which rapid cooling — cold-water immersion in exertional heat stroke — determines survival: "cool first, transport second".
Why it matters in the exam
The classic question describes a soldier or young runner who collapsed during exertion on a hot day, confused, with a temperature of 41 °C, or an older person in a heat wave found confused at home with hot skin. The exam tests the distinction between heat exhaustion (normal consciousness, temperature below 40) and heat stroke (altered consciousness), and the choice of the right cooling: cold-water immersion in exertional heat stroke, and evaporative cooling (spray and fan) in an older person with classic heat stroke.
A standard distractor is giving antipyretics such as paracetamol — they do not work because the fever is not a change in the brain's set point. Dantrolene is not a proven treatment either. Temperature must be measured rectally, because oral or ear readings mislead, and cooling continues to about 38.5–39 °C and then stops to avoid hypothermia.
Complications are also asked: rhabdomyolysis and kidney failure, disseminated intravascular coagulation, liver injury that peaks after one to three days, hypoglycaemia and seizures. The differential diagnosis includes central nervous system infection, sympathomimetic or anticholinergic poisoning, serotonin syndrome, NMS, thyroid storm and malignant hyperthermia. Prevention — drinking, gradual acclimatisation and stopping exertion — is part of the questions in the military context.
Key points
- Heat stroke = 40 °C or more + nervous system dysfunction.
- Exertional — cold-water immersion; classic in the elderly — evaporative cooling.
- Cool to 38.5–39 °C and stop.
- Antipyretics have no role.
- Look for rhabdomyolysis, kidney failure, DIC and liver injury.
Summary table
| Condition | Core temperature | Consciousness | Treatment |
|---|---|---|---|
| Heat cramps | Normal or slightly raised | Normal | Rest, salt and fluids |
| Heat exhaustion | Below 40 °C | Normal (weakness, nausea, dizziness) | Remove from heat, lie down, fluids, cooling |
| Exertional heat stroke | 40 or more | Confusion, seizures, coma | Cold-water immersion at once, to 38.5–39 |
| Classic heat stroke | 40 or more | Altered consciousness | Evaporative cooling, spray and fan, ice to axillae and groins |
| Complications | — | — | Rhabdomyolysis, kidney failure, DIC, liver injury, hypoglycaemia |
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Sources
- Wilderness Medical Society Clinical Practice Guidelines for the Prevention and Treatment of Heat Illness, 2019 update — Treatment of heat stroke
- American College of Sports Medicine Expert Consensus Statement on exertional heat illness, 2023 — Cold-water immersion
- Tintinalli's Emergency Medicine: A Comprehensive Study Guide, 9th edition (2020) — Heat emergencies
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.