Heat stroke

Revision as of 12:15, 26 August 2015 by Rossdonaldson1 (talk | contribs) (Treatment)

Background

  • Universally fatal if left untreated
  • Types
    • Classic (nonexertional)
      • Seen in children and elderly
    • Exertional
      • Seen in otherwise young, healthy individuals

Clinical Features

  • Heat exposure + elevated temperature >40C (>104F) + neurologic abnormalities:
  • Anhidrosis is frequently present; however, its absence does NOT rule out heat stroke

Differential Diagnosis

Environmental

Environmental heat diagnoses

Non-Environmental

Altered mental status and fever

Diagnosis

  • Diagnosis is made by history and physical exam and exclusion of other diseases
  • Blood glucose
  • CBC
  • Chemistry
  • Arterial blood gas or Venous blood gas
    • PaCO2 is often <20 2/2 hyperventilation
  • Lactate
    • Often elevated in exertional heat stroke
  • Coagulation studies
  • Creatine phosphokinase
  • Urinanalysis
  • ECG
  • Chest x-ray
  • CT brain and/orLP as needed

Treatment

General

  • Remove from environment
  • Address airway, breathing and circulation
  • IV normal saline
    • Bolus if hypotensive
    • Titrate to urine output, start at 250mL/hour
    • Avoid aggressive IV fluid resuscitation unless severely dehydrated

Cooling

  • Mainstay of treatment
  • Goal is to reduce temp to 39C (102.2F) and then stop 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

Complications

  • 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

Disposition

  • All patients require admission

See Also

References

Waters T. Heat Emergencies In: Tintinalli's Emergency Medicine: A Comprehensive Study Guide. 7th ed. McGraw Hill Medical. 2011: 1339