Management of heat stroke
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I now have comprehensive content from authoritative emergency medicine sources. Here is a structured overview of heat stroke management:
Management of Heat Stroke
Definition & Cardinal Features
Heat stroke is an acute, life-threatening emergency defined by:
- Core temperature >40°C (>104°F)
- Altered mental status (ranging from confusion and ataxia to delirium, seizures, and coma)
Anhidrosis is NOT a required diagnostic criterion — over 50% of patients are still diaphoretic at presentation. The cerebellum is particularly heat-sensitive; ataxia may be an early sign.
Two forms exist — classic (non-exertional, typically elderly/very young) and exertional (young healthy individuals during exercise) — but this distinction does not change management, and delay in cooling increases mortality.
Diagnosis
No single diagnostic test confirms heat stroke; diagnosis is clinical (history + hyperthermia + altered mental status) after excluding other causes.
Differential diagnosis includes:
- Infection: sepsis, meningitis, encephalitis, malaria
- Neurologic: hypothalamic hemorrhage, stroke, status epilepticus
- Endocrine: thyroid storm, pheochromocytoma, DKA
- Toxicologic: anticholinergic toxidrome, sympathomimetic OD, salicylate OD, serotonin syndrome, malignant hyperthermia, neuroleptic malignant syndrome, alcohol/benzo withdrawal
Workup:
- CBC, CMP, coagulation profile (PT, PTT), creatine kinase, myoglobin, urinalysis, ABG
- ECG ± troponin if cardiac ischemia suspected
- Head CT ± LP if CNS pathology is in the differential
- Lactate (exertional heat stroke commonly has lactic acidosis)
- Glucose (hypoglycemia may occur)
Monitor core temperature with rectal probe, esophageal thermometer, or temperature-equipped urinary catheter — oral and tympanic temperatures are inaccurate.
Immediate Management
1. Airway, Breathing, Circulation
- Initiate standard resuscitation immediately
- Intubate if obtunded or hemodynamically unstable
- Establish IV/central access as needed
- Check point-of-care glucose
2. Cooling — The Most Critical Intervention
Goal: reduce core temperature to ≤39°C (102.2°F), ideally within 30 minutes. Avoid overshoot hypothermia.
| Method | Details | Notes |
|---|---|---|
| Cold water immersion | Immerse (undressed) in ice-water tub, head out of water | Most efficient in young/healthy; gold standard for exertional HS; impairs monitoring |
| Evaporative cooling | Spray cool water (~15°C) on skin + fan directed over patient | Practical, tolerated; impaired in high humidity |
| Ice packs | Groin, axillae, neck | Adjunct only; not primary method |
- No one method has proven superiority; use whichever is readily available and achieves rapid cooling
- If one method is not rapidly effective, switch to another
- Antipyretics (NSAIDs, acetaminophen) are NOT indicated — heat stroke is not pyrexia-mediated and antipyretics won't help
- Dantrolene is NOT indicated (unlike malignant hyperthermia/NMS)
- Stop cooling when core temperature reaches 39°C; monitor for rebound hyperthermia at 3–6 hours
Shivering during cooling: treat with short-acting benzodiazepines (first-line). Phenothiazines (second-line) may lower seizure threshold, cause hypotension, and impair sweating via anticholinergic effects.
3. Fluid Management
- Administer IV crystalloids (normal saline) to maintain adequate urine output
- Bolus 1–2 L for hypotension
- Use invasive hemodynamic monitoring in elderly or patients with cardiovascular disease
- Administer cautiously to normotensive patients
4. Vasopressors (if refractory hypotension)
- Dopamine or dobutamine preferred once CVP reaches 12–14 mmHg after fluid resuscitation
- Avoid pure α-adrenergic agents (e.g., norepinephrine) as vasoconstriction redirects blood away from the skin, impairing cooling
Complications
| System | Early | Late |
|---|---|---|
| Vital signs | Hypotension, hypothermic overshoot, hyperthermic rebound | — |
| Neurologic | Delirium, coma, seizures | Cerebral edema, encephalopathy, persistent deficits |
| Cardiac | Heart failure | Myocardial injury |
| Pulmonary | Pulmonary edema | ARDS |
| Renal | Oliguria | Renal failure (from rhabdomyolysis, direct thermal injury, volume depletion) |
| Muscular | Rhabdomyolysis | — |
| GI/Hepatic | — | Intestinal ischemia, hepatic dysfunction (peaks 24–72 hrs, usually reversible), pancreatic injury |
| Metabolic | Hypokalemia, hypernatremia/hyponatremia | Hyperkalemia, hypocalcemia, hyperuricemia |
| Hematologic | — | Thrombocytopenia, DIC |
Rhabdomyolysis is managed with aggressive IV hydration to maintain urine output >1 mL/kg/hr. Myoglobinuria can precipitate acute tubular necrosis.
DIC/coagulopathy: thermal endothelial injury → platelet aggregation, decreased clotting factors, fibrinolysis — monitor coagulation parameters closely.
Prehospital Pearls
- Remove patient from hot environment immediately
- Remove clothing; begin evaporative cooling or apply ice packs
- IV bolus if hypotension present
- Check glucose if altered mental status
- Transport without delaying cooling
Sources: Tintinalli's Emergency Medicine, p. 1389–1391; Washington Manual of Medical Therapeutics, p. 987–988
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