Heat Stroke vs Heat Exhaustion
Objective: Tell heat exhaustion from heat stroke, start cooling on scene, and treat this as a time-critical brain-and-organ emergency — not “they just need water.”
Why This Is Hard
Football practice, warehouse, elderly apartment with no AC — crews delay cooling to “get a temperature” or start an IV. Wilderness Medical Society and AHA 2025 hyperthermia teaching: heat stroke is a clinical diagnosis (hyperthermia with CNS dysfunction). Cooling is the treatment. Delay cooks the brain and the liver.
- Altered + hot environment / hot skin → heat stroke until you have a better story
- Cool first — ice-water immersion when available and trained
- Sweat can still be present — “dry skin required” is a myth
- Glucose, naloxone picture, sepsis, tox — still look, but do not skip cooling
Exhaustion vs Stroke (Education)
- Heat exhaustion: dizziness, nausea, headache, tachycardia, thirsty or volume-down. Mentation is largely intact. Shade, strip excess clothing, oral fluids if they can protect the airway, monitor, and do not send them back to work hot.
- Heat stroke: same setting plus CNS dysfunction — confusion, seizure, coma, combativeness. Core temp is often ≥40 °C when you can measure, but do not withhold cooling because the tympanic number looks “only” 39.
- Exertional (athlete, laborer) vs classic/non-exertional (elderly, anticholinergic, no AC). Both die. Classic patients may look dry; exertional patients often still sweat.
Cooling That Matters
- Best field method: ice-water (or the coldest water you have) immersion — WMS 2024 strong recommendation, high-quality evidence. Do not delay cooling to start an IV or to “get a better core temp.” Treat empirically when the picture fits.
- If you cannot immerse: strip, ice-water towels/sheets over as much skin as you can, mist and fan. A few chemical packs only at neck/axilla/groin is outdated as a primary method (WMS: if chemical packs are all you have, cheeks/palms/soles beat the old “major vessel” sites; whole-body ice is still better).
- Antipyretics (acetaminophen, ibuprofen) do not treat heat stroke. Airway, glucose, seizure care (see seizure). Benzos for shivering/seizure per protocol — not a substitute for cooling.
- IV fluids for shock/rhabdo risk per protocol. Do not dump pressors into an uncooled patient as the first move. Cool while you package — do not wait for the ED shower.
Field Pitfalls
- Requiring dry skin to call heat stroke.
- Skipping cooling because “we’ll be at the hospital in 8 minutes.”
- Calling it psychiatric because they are combative and hot.
Practice
60-second drill
Partner: August football collapse, GCS 10, still sweating. Name diagnosis framing and the first cooling method you actually have on a typical engine vs a stadium ice tub.
Related: AMS Framework, Seizure, Sepsis.
Sources & Further Study
Named guidelines for further study. They are not clinical orders and do not replace your protocol or medical direction.
- NASEMSO National Model EMS Clinical Guidelines (2022) — U.S. EMS model language; protocol still wins
- AHA 2025 Part 10: Special Circumstances — hyperthermia / heat stroke
- Wilderness Medical Society Clinical Practice Guidelines for the Prevention and Treatment of Heat Illness: 2024 Update — ice-water immersion first; evaporative/sheet cooling if you cannot immerse; treat empirically even without a core temperature
- Cool on scene. Protocol owns destination and when to stop active cooling. Typical EMS still transports after field cooling — do not copy wilderness “release to self-care” language onto a 911 response.
Education only. Apply learning within your protocols and medical direction. This is not clinical care guidance.
Check Your Understanding
Street decisions from this lesson only. After you check, the key is highlighted. Education practice — not a certification exam.