Heat stroke & heat exhaustion - Clinical summary for ED practice
This section summarises recognition, assessment and management of heat‑related illness encountered in emergency practice, following current UK guidance (Resuscitation Council UK; UK Health Security Agency [UKHSA]; RCEM). Emphasise early recognition and immediate cooling because time to effective cooling strongly influences outcome.
Definitions and classification
- Heat stroke is a life‑threatening thermoregulatory failure defined by core temperature
> 40.0°C with central nervous system dysfunction (encephalopathy: confusion, agitation, seizures, reduced consciousness). Heat stroke may trigger a systemic inflammatory response syndrome and rapid multi‑organ dysfunction (Resuscitation Council UK; UKHSA).
- Heat exhaustion is a milder heat illness with core temperature raised but < 40.0°C, typically presenting with headache, nausea, dizziness, weakness and profuse sweating; orthostatic hypotension from salt/water depletion is common (UKHSA).
- Types of heat stroke:
- Exertional heat stroke occurs during strenuous activity in heat in otherwise fit individuals (athletes, military recruits). Rapid, on‑site cooling (cold‑water immersion) is highly effective.
- Classic (non‑exertional) heat stroke affects older or vulnerable people during prolonged environmental heat exposure (heatwaves) and is often complicated by comorbidity and medications.
Distinguishing heat exhaustion from heat stroke
- Heat exhaustion: core temperature < 40.0°C; profuse sweating; symptoms typically improve rapidly with cooling and rehydration.