Heat Exhaustion

(aka Heat Prostration, Heat Collapse)


  • Most common heat syndrome


  • Failure of cardiovascular response to high external temperatures
  • Pathogenic types:
    • Water depletion type: common in elderly patients on diuretics/ those with inadequate hydration in hot environment
    • Salt depletion type: inadequate salt replacement/ accompanied by hyponatremia and hypochloremia


Multisystem disease:
-Neuro: weakness/ anxiety/ fatigue/ thirst/ vertigo/ headache/ faintness/ hyperventilation/ muscular incoordina-tion/ agitation/ impaired judgement/ confusion
-GI: N/V/ anorexia/ urge to defecate
-Heat syncope (heat collapse):
occurs in both active and sedentary patients/ usually sudden onset with brief duration/ ashen-gray color during event with cool, clammy skin/ mydriasis/ tachycardia/ orthostatic hypotension
-Other: hyperthermia (present usually only in water depletion type)


  • Rest in cool environment in supine position: spontaenous recvoery usually follows
  • Fluid and electrolyte replacement:


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