Generally associated with core temperatures >104°F (>40°C), though heat stroke can occur at lower core temperatures.
Diagnosis rests on the observation of profound central nervous system dysfunction in the presence of hyperthermia.
Medications may predispose patients to heat stroke (e.g., diuretics, antihypertensives).
Early cooling reduces mortality and morbidity, and should be initiated as soon as possible.
Evaporation and ice water immersion are both widely used as cooling methods.
Patients are at risk of multisystem organ failure, so careful monitoring is essential even after return to normothermia.
This topic covers the management of both heat stroke and heat exhaustion in adults.
Heat stroke is defined as central nervous system (CNS) dysfunction in the setting of hyperthermia. It is associated with core temperature >104°F (>40°C), and typically ranges from 104°F to 111.2°F (40°C to 44°C), although higher core temperatures have been reported. It should be suspected in the setting of high heat stress, through either exertion or environmental factors. Heat stroke can occur at core temperatures <104°F (40°C).
Heat exhaustion is a milder form of heat illness, where profound CNS disturbance is absent. In this case the core temperature is elevated (98.6°F to 104°F [37°C to 40°C]), but to a lesser extent than in heat stroke.
History and exam
Key diagnostic factors
- profound central nervous system disturbance
Other diagnostic factors
- nausea and vomiting
- muscle tenderness
- gastrointestinal bleeding
- bruising and skin bleeding
- older age
- impaired cognition
- patients unable to care for themselves
- people who are unacclimatized to hot environments
- young, active people exercising intensely under hot, humid conditions
1st investigations to order
- core temperature measurement
- serum electrolytes
- metabolic profile
- renal function tests
- creatine kinase
- prothrombin time, activated PPT, and INR
- lactic acid
- chest x-ray
- arterial blood gas
- medication/toxicology screen
- thyroid function tests
- plasma glucose
Investigations to consider
- cranial CT scan
- lumbar puncture
- blood culture
- Diabetic ketoacidosis
- National Athletic Trainers’ Association Position Statement: Exertional Heat Illnesses
- Wilderness Medical Society Practice Guidelines for the Prevention and Treatment of Heat-Related Illness: 2014 Update
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