Exertional heat stroke plays out over minutes, and field management is a sequence of specific decisions, not a single action. This guide walks through each turning point in the order it actually occurs on scene, from recognising the signs through to transport.

Step 1: Recognise the signs

The first decision point is confirming this is exertional heat stroke. Signs to look for in someone who has just performed intense physical exertion in the heat:

  1. Confusion, disorientation, incoherent speech: the central neurological sign, present even in a patient who is still conscious
  2. Ataxia, unsteady gait: common in runners who stagger before collapsing
  3. Hot skin: sweating may be present or absent, it is not a reliable criterion for ruling out the diagnosis
  4. Elevated heart rate persisting after exertion has stopped
  5. Loss of consciousness, in the most severe presentations

Any confusion after exertion in the heat should be treated as exertional heat stroke until proven otherwise. There is no need to wait for loss of consciousness to act.

Step 2: Decide, cool before transporting

This is the most consequential decision point, and the one where mistakes cost the most. The natural instinct is to call for help and wait. That instinct kills.

The Cool First, Transport Second protocol, formalised by the ACSM (2023), the IOC (Hosokawa Y, Racinais S et al., BJSM 2021), and endorsed by the SFAR, reverses that order:

  1. Begin cold water immersion immediately, on site
  2. Call emergency services in parallel, never in place of cooling
  3. Transport only once cooling is underway

The Korey Stringer Institute (Dr Douglas Casa, University of Connecticut) has tracked over 3,000 exertional heat stroke cases: 100% survival when core temperature drops below 40°C within 30 minutes of symptom onset. Every minute spent waiting for help to arrive before cooling begins consumes that window.

Step 3: Immerse in cold water, full body

Once the decision to cool has been made, method matters as much as speed of decision. Casa et al. (Exercise and Sport Sciences Reviews, 2007) established that full-body cold water immersion cools at 0.20 to 0.35°C per minute, versus 0.03°C per minute for localised ice packs. It is the only method fast enough to reach the therapeutic target within the 30-minute window.

Practical points at this stage:

Step 4: Monitor and know when to stop cooling

Stopping cooling is not an arbitrary call, it is a temperature target. Immersion should continue until core temperature reaches approximately 38.5°C, measured rectally if possible, the only reliable field method.

Two symmetrical mistakes threaten this stage:

Only continuous temperature monitoring resolves this. That is why physical access to the patient throughout immersion, to place and read a temperature probe, is an operational requirement, not a comfort detail.

Step 5: Reassess if the patient becomes unresponsive

A worsening level of consciousness during management of exertional heat stroke should never be assumed by default to be a simple progression of hyperthermic neurological impairment. As soon as a patient stops responding:

  1. Check breathing: is it present, normal, effective?
  2. Check for a pulse (carotid): is it present?
  3. Only continue immersion without further intervention if breathing and pulse are confirmed present and effective

This check takes seconds and determines everything that follows.

Step 6: Start CPR and use an AED if there is no pulse or breathing

If breathing is absent or abnormal, or no pulse is detected, this is cardiac arrest, a distinct emergency that takes priority over everything else:

  1. Begin cardiopulmonary resuscitation (chest compressions) without delay, following the standard basic life support sequence
  2. Attach an automated external defibrillator (AED) as soon as one is available and follow its prompts
  3. Do not interrupt resuscitation for an extended period to continue cooling: chest compressions and ventilation take priority for as long as cardiac arrest persists
  4. Resume or continue cooling as soon as the situation allows (return of pulse, additional personnel available to take over), without ever abandoning it for good once the patient is stabilised

This sequence follows the same logic Dr Douglas Casa himself uses when he compares the urgency of the cooling protocol to that of a defibrillator during cardiac arrest: an action that must be automatic, immediately available, and never delayed by waiting for outside clearance.

Step 7: Transport once cooling is underway

Transport is not the first action, it comes once cooling is firmly underway or the therapeutic target has been reached. Monitoring does not stop during transport: persistent confusion, seizure activity, or failure to return to a normal level of consciousness after cooling are signs of more severe neurological involvement and should accelerate hospital care.

What this means for field equipment

Every one of these decisions assumes an immersion capability is available immediately, on the scene itself, not in a vehicle some distance away. The Kollder emergency cooling tub deploys in under 2 minutes by a single operator, with no tools required, and its fully open design preserves complete medical access (thermometry, IV line, airway management) throughout immersion, including if reassessment or CPR becomes necessary. Request a quote at kollder.com/#contact.

Further Reading

Sources: ACSM Expert Consensus Statement, 2023, Hosokawa Y, Racinais S et al., IOC/BJSM, 2021, Casa DJ et al., Exercise and Sport Sciences Reviews, 2007, Korey Stringer Institute (Dr Douglas Casa, University of Connecticut), SFAR.

Kollder is the emergency cooling tub that deploys in under 2 minutes, anywhere.

Request a quote