Heat stroke

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  • Severe end of heat-related illness spectrum
  • True emergency - universally fatal if left untreated
    • Mortality approaches 30% even with treatment[1]


  • Classic (nonexertional) - insidious development over days
    • Seen in children and elderly
  • Exertional - rapid onset during exercise or other exertion
    • Seen in otherwise young, healthy individuals

Clinical Features

  • Symptoms[2]
  • Anhidrosis is frequently present; however, its absence does NOT rule out heat stroke

Differential Diagnosis

Environmental heat diagnoses


Altered mental status and fever



  • Core temperature (continuous monitoring is ideal, e.g. with bladder temperature monitor)
  • Blood glucose
  • CBC
  • Metabolic panel
  • LFTs (AST>1000 indicates poor prognosis)
  • Blood gas
  • Lactate
  • Coagulation studies
  • Creatine phosphokinase and myoglobin
  • Urinalysis
  • ECG
  • Chest x-ray
  • CT brain (± LP), if indicated


  • Clinical diagnosis


  • Address ABCs
  • Rapid cooling (see below) - mainstay of treatment
    • Reduces morbidity/mortality, should be started in prehospital setting if no other life-threats exist[2]
  • Remove from environment
  • IVF (for renal protection and avoiding rhabdomyolysis)
    • Bolus if hypotensive
    • Infusion titrated to UOP (goal 250mL/hour)

Rapid Cooling

  • Goal is to reduce temp to 39°C (102.2°F) - take care to avoid overshoot hypothermia
  • Antipyretics (ASA and acetaminophen) and dantrolene have no role
  • Cooling blankets work too slowly to be employed as sole treatment
  • Ice packs to neck, axillae, groin are useful as adjunct only
  • Cold IVF is not effective
  • Techniques
    • Evaporative
      • Method of choice
      • Spray cool water (15C (59F)) on most of pt's body surface; turn on fan
      • Complications
        • Shivering (occurs when skin temp is <30C (86F): treat with short-acting benzodiazepines
        • Electrodes not sticking: place on pt's back instead
    • Ice-water immersion
      • Consider especially in young, healthy pts
      • Complications
        • Shivering
        • Inability to perform defibrillation or resuscitative procedures
    • Invasive
      • Consider if evaporative cooling or immersion is insufficient
      • Cardiopulmonary bypass
      • Cold water gastric, bladder or rectal lavage


  • Hypotension
    • BP will usually respond to small fluid bolus (500cc) and body cooling
      • If ineffective consider vasopressors (dopamine or dobutamine)
      • Avoid peripheral vasoconstriction (norepinephrine)
        • May redirect blood flow away from skin
  • Electrolyte abnormalities
    • Variable: hypokalemia and hyper or hyponatremia may be seen
  • Hematologic
    • DIC or abnormal bleeding
  • Hepatic injury
    • Almost always reversible
  • Renal failure
  • ARDS
  • Seizure
  • Neurologic deficit
    • Persistent in 20%, associated with high mortality


  • All patients require admission

See Also


  1. Gaudio FG, Grissom CK. Cooling Methods in Heat Stroke. J Emerg Med. 2015 Oct 31.
  2. 2.0 2.1 Becker JA, Stewart LK. Heat-related illness. Am Fam Physician. 2011 Jun 1;83(11):1325-30.