Management of Heat Stroke

Definition & Cardinal Features

• Core temperature > 40°C (104°F)
• Altered mental status (confusion, ataxia, seizures, coma)

Immediate Prehospital Care

1. Remove from hot environment immediately
2. Remove all clothing
3. Begin cooling at once using any available method:
   • Spray with water + fan airflow
   • Wet towels/sheets over the body
   • Ice packs
4. Check point-of-care glucose if altered mental status is present
5. Administer IV fluid bolus en route if obtunded or hemodynamically unstable

ED Resuscitation

Airway & Hemodynamics

• If obtunded or hemodynamically unstable → consider intubation and central venous access
• IV crystalloids to maintain adequate urine output (50–100 mL/hr)
• In elderly or cardiac patients: consider invasive hemodynamic monitoring
• Check glucose and correct hypoglycemia

Temperature Monitoring

• Use rectal probe, temperature-equipped urinary catheter, or esophageal thermometer
• Oral and tympanic temperatures are unreliable in heat stroke
• Target: reduce core temperature to ~39°C (102.2°F) — ideally within 30 minutes
• Stop active cooling at 39°C to avoid hypothermic overshoot
• Watch for temperature rebound at 3–6 hours post-cooling

Cooling Techniques

• No single method has been proven superior — use what is available and effective
• If the initial method does not lower temperature quickly, switch methods
• Antipyretics (e.g., paracetamol, NSAIDs) are NOT indicated — heat stroke is not PGE2-mediated
• Dantrolene is NOT indicated (no role unlike malignant hyperthermia)

Managing Shivering During Cooling

• First line: short-acting benzodiazepines (e.g., lorazepam, diazepam)
• Second line: phenothiazines (use cautiously — lower seizure threshold, cause hypotension, impair sweating via anticholinergic effect)

Investigations (Directed at End-Organ Damage)

• CBC, coagulation profile (PT/aPTT), fibrinogen
• Electrolytes, BUN, creatinine, glucose, calcium
• CK, myoglobin, urinalysis (rhabdomyolysis)
• LFTs (hepatic injury peaks at 24–72 hours)
• ABG (PaCO₂ often <20 mmHg due to hyperventilation; lactic acidosis in exertional)
• ECG ± troponin if cardiac ischemia suspected
• CT head ± LP to exclude CNS causes of altered mental status

Management of Complications

Hypotension

• First: 20 mL/kg crystalloid bolus + initiate cooling
• If CVP reaches 12–14 mmHg and hypotension persists → dopamine or dobutamine
• Avoid pure α-agonists (e.g., norepinephrine) — vasoconstriction shunts blood away from skin and impairs cooling

Seizures

• Benzodiazepines (lorazepam IV) are first-line
• Monitor closely during cooling (seizures are common at this phase)

Rhabdomyolysis / AKI

• Aggressive IV crystalloid hydration to maintain urine output > 50 mL/hr
• Monitor CK, creatinine, urine myoglobin

Electrolyte Abnormalities

• Hypokalemia: total-body depletion — replete cautiously
• Hyperkalemia: may result from rhabdomyolysis/AKI
• Hypernatremia: severe dehydration
• Hyponatremia: hypotonic oral hydration

DIC / Coagulopathy

• Thermal endothelial injury → platelet aggregation, clotting factor deactivation, DIC
• Treat with FFP, platelets as appropriate

Hepatic Injury

• Nearly always reversible with full recovery
• LFTs peak at 24–72 hours (centrilobular necrosis)

Complications Summary

Disposition

• All heat stroke patients require ICU admission
• Continue monitoring for temperature rebound and multi-organ dysfunction for at least 24–48 hours