Heat Stroke: Rapid Differentiation and Cooling Protocol

Classic vs. Exertional Heat Stroke

These are two different patient populations with different presentations.

Classic heat stroke occurs in elderly, young children, and chronically ill patients during heat waves. Minimal physical activity. The body's cooling system fails from prolonged passive exposure.

• Skin is often hot and DRY — the sweat mechanism has failed
• Develops over hours to days
• Common in confined spaces, lack of air conditioning

Exertional heat stroke occurs in athletes, military personnel, and laborers during intense activity in heat.

• Skin may still be wet from sweating even when core temperature is dangerously elevated
• Can develop within 30-60 minutes of beginning exertion
• Younger, otherwise healthy individuals
• Muscles are also producing large amounts of heat

The treatment is identical. The presentation differs. Do not assume heat stroke is absent because the patient is young and fit, or because they are still sweating.

The Cooling Protocol

Time to cooling is what determines neurological outcome. For every 5 minutes that a patient remains above 40°C, brain and organ damage accumulates. The goal is aggressive cooling started immediately, not after evacuation.

Cold Water Immersion (Preferred)

If you have access to a tub, stream, or container large enough:

1. Remove clothing. Keep the patient's head above water.
2. Immerse the patient in cold water (10-15°C / 50-59°F is ideal; use whatever is available).
3. Agitate the water continuously — still water around the patient warms quickly.
4. Monitor mental status and temperature continuously.
5. Remove from immersion when temperature reaches 39°C (102.2°F) to prevent overcorrection.

Cold water immersion reduces core temperature approximately 0.2°C per minute. A patient presenting at 41.5°C can reach 39°C in roughly 12 minutes with good immersion technique.

Ice Sheet Method (Alternative)

When full immersion is not possible:

1. Lay wet sheets in a cold stream or on ice/snow.
2. Place the patient on the sheets, wrap loosely.
3. Replace sheets every 5-10 minutes as they warm.
4. Fan aggressively — evaporative cooling + convection significantly accelerates the method.

Less effective than immersion but substantially better than ice packs alone.

Ice Pack Application (Field Minimum)

When nothing else is available:

• Apply ice packs, cold wet cloths, or chemical cold packs to:
  • Both armpits
  • Neck (both sides)
  • Groin (both sides)
• Fan continuously
• Replace packs as they warm
• Spray skin with water and fan — evaporative cooling adds meaningful effect

Do Not Use

Antipyretics (ibuprofen, acetaminophen) — Have no mechanism of action in heat stroke. Do not waste time administering them.

Alcohol rub-downs — Historically taught, now discouraged. Alcohol evaporates too quickly to provide sustained cooling, and systemic absorption through skin is a real concern, particularly in children.

Cooling below 38°C aggressively — Overshoot causing hypothermia is a real risk. Monitor temperature and stop aggressive cooling at 39°C.

Signs of Heat Stroke Requiring Immediate Action

Any of these presentations should trigger immediate cooling without waiting for temperature confirmation:

• Confusion, combativeness, or inappropriate behavior in someone exposed to heat
• Seizure during heat exposure or immediately after
• Loss of consciousness
• Inability to follow commands in a context where heat exposure has occurred
• Staggering gait or sudden collapse during exertion in heat

Do not attempt to measure temperature before beginning cooling if the patient clearly has altered mental status and heat exposure. Cool immediately, measure when you can.

During Transport

Cooling does not stop for transport. If evacuating a heat stroke patient:

• Strip, wet, and fan continuously in the vehicle
• Apply ice to the major vessel areas if available
• Position windows and vents for maximum airflow
• Do not bundle the patient

A heat stroke patient who has been cooled to below 39°C before hospital arrival has dramatically better outcomes than one who arrives still hyperthermic.

After Cooling

Heat stroke patients who survive and appear to recover may have:

• Renal impairment (rhabdomyolysis from muscle breakdown)
• Hepatic injury
• Coagulopathy
• Neurological sequelae in severe cases

Even patients who appear fully recovered after cooling should be evaluated medically. Heat stroke is not "just overheating" — it is multi-organ injury that may not be clinically apparent for 24-48 hours.

Heat Exhaustion Management

Heat exhaustion is not heat stroke, but it can progress to heat stroke if untreated.

Treatment:

• Remove from heat immediately
• Lie the patient down in shade or cool environment
• Remove excess clothing
• Oral rehydration — water plus electrolytes (sports drink, ORS, salted broth)
• Cool with fans and wet cloths
• Assess frequently — if mental status changes, treat as heat stroke

A patient with heat exhaustion who fails to improve with 30 minutes of rest and rehydration, or whose mental status deteriorates, has crossed into heat stroke. Escalate treatment immediately.