Heat stroke

Background

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

Diagnosis

1. Heat exposure + elevated temperature >40C (>104F) + neurologic abnormalities:
   1. Inappropriate behavior
   2. Confusion
   3. Delirium
   4. Ataxia
   5. Coma
   6. Seizures
2. Anhidrosis is frequently present; however, its absence does NOT rule out heat stroke
   1. Symptoms seen in Heat Exhaustion may also be present

Differential Diagnosis

Environmental heat diagnoses

• Heat cramps
• Heat edema
• Heat exhaustion
• Heat tetany
• Heat stroke
• Heat syncope
• Miliaria
• Hyperthermia

Non-Environmental

• Infectious
  • Sepsis
  • Meningitis
  • Encephalitis
  • Malaria
  • Typhoid
  • Tetanus
• Endocrine
  • Thyroid Storm
  • Pheochromocytoma
  • DKA
• Neurologic
  • Hypothalamic bleeding or infarct
  • CVA
  • Status epilepticus
• Toxicologic
  • Anticholinergic toxidrome
  • Sympathomimetic overdose
  • Salicylate overdose
  • Serotonin syndrome
  • Malignant hyperthermia
  • Neuroleptic Malignant Syndrome
  • Withdrawal (ETOH, benzo)

Work-Up

1. Blood sugar
2. CBC
3. Chemistry
4. VBG
   1. PaCO2 is often <20 2/2 hyperventiltaion
   2. Exertional heat stroke often results in lactic acidosis
5. Coags
6. CK
7. UA
8. ECG
9. CXR
10. ?CT/LP

Treatment

General

1. IVF
   1. Initiate at a rate that ensures adequate (start w/ NS 250cc/hr)

Cooling

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

Complications

1. Hypotension
   1. BP will usually respond to small fluid bolus (500cc) and body cooling
      1. If ineffective consider pressors (dopamine or dobutamine)
2. Electrolyte abnormalities
   1. Variable: hypokalemia and hyper or hyponatremia may be seen
3. Hematologic
   1. DIC or abnormal bleeding
4. Renal failure
5. ARDS
6. Seizure
   1. Tx w/ benzos

See Also

• Heat Emergencies
• Heat Exhaustion
• Acute Fever (DDX)

Source

Tintinali