heat exhaustion

Epidemiology

• occurs most commonly in individuals:
  • poorly aclimatized to a hot environment
  • in poor physical condition
• elderly, especially those taking diuretics are more prone to heat illness

Pathology

• increased body temperature
• cardiac output increases
• blood vessels in skin dilate
• blood is shunted to periphery of body

Clinical manifestations

• manifestations common to all forms of heat injury
  • headache
  • weakness
  • nausea & vomiting
  • vertigo
  • faintness
  • tachycardia
  • hypotension
  • pallor
• other manifestations
  • flu-like syndrome
  • anorexia
  • urge to defecate
  • copious sweating
  • normal or subnormal body temperature
  • cold, clammy skin
  • dilated pupils

Laboratory

• complete blood count
• electrolytes
• urinalysis

Diagnostic procedures

• electrocardiogram

Differential diagnosis

• heat stroke (only core temperature can distinguish heat exhaustion from heat stroke)
• sepsis
• myocardial infarction

Management

• recumbent position
• rest in cool environment
• hypotonic fluid replacement
• follow-up within 1 week
  • ensure complete recovery
  • work-up & management of pre-existing illnesses as indicated
• patient education
  • acclimatize slowly to hotter, more humid environments
  • adequate hydration

More general terms

• heat injury; heat stress; heat illness

Additional terms

• hyperthermia (pyrexia)