What is the treatment for hyperthermia?

Treatment of Hyperthermia

The treatment of hyperthermia requires immediate cooling measures including cold saline infusion, surface cooling with ice packs, and administration of dantrolene in cases of malignant hyperthermia to rapidly reduce core body temperature and prevent multi-organ failure. 1, 2

Immediate Assessment and Management

1. Identify the cause of hyperthermia:

   • Malignant hyperthermia (MH): Associated with exposure to volatile anesthetics or succinylcholine
   • Environmental/exertional heat stroke: Associated with exposure to hot environments or strenuous activity
   • Other causes: Drug reactions, endocrine disorders, infections

2. Initial interventions:

   • Remove from heat source or stop triggering agents (if MH)
   • Establish IV access with wide-bore cannulas
   • Begin continuous monitoring (temperature, ECG, blood pressure, oxygen saturation)
   • Obtain baseline labs: electrolytes, CK, arterial blood gases, myoglobin, glucose 1

Cooling Measures

For all hyperthermia cases:

• Administer 2000-3000 ml of chilled (4°C) 0.9% saline IV 1, 2
• Apply surface cooling:
  • Wet, cold sheets
  • Fans for evaporative cooling
  • Ice packs placed in the axillae and groin
  • Continue cooling until temperature < 38.5°C 1

For malignant hyperthermia specifically:

• Stop all trigger agents immediately (volatile anesthetics, succinylcholine)
• Hyperventilate with 100% O₂ at high flow
• Change to non-trigger anesthesia (TIVA) if anesthesia must be continued
• Inform surgeon and request termination/postponement of surgery 1

Medication Management

For malignant hyperthermia:

• Dantrolene: 2 mg/kg IV initially (20 mg ampoules mixed with 60 ml sterile water)
  • Repeat until cardiac and respiratory systems stabilize
  • May exceed maximum dose of 10 mg/kg if necessary
  • Continue 4-8 mg/kg/day in divided doses for 1-3 days to prevent recurrence 1, 2

For hyperkalemia (common in severe hyperthermia):

• Calcium chloride: 0.1 mmol/kg IV
• 50% dextrose: 50 ml with 50 IU insulin (adult dose)
• Consider dialysis for severe, refractory hyperkalemia 1, 2

For acidosis:

• Hyperventilate to normocapnia
• Sodium bicarbonate IV if pH < 7.2 1

For arrhythmias:

• Amiodarone: 300 mg for adults (3 mg/kg IV)
• β-blockers (propranolol/metoprolol/esmolol) if tachycardia persists 1

Maintaining Organ Function

• Target urine output > 2 ml/kg/h:

  • Furosemide 0.5-1 mg/kg
  • Mannitol 1 g/kg
  • Crystalloid fluids (lactated Ringer's or 0.9% saline) 1, 2

• Monitor for complications:

  • Compartment syndrome
  • Myoglobinuria
  • Coagulopathy
  • Renal and hepatic dysfunction 1, 2

Monitoring and Follow-up

• Monitor patient for minimum of 24 hours in ICU/HDU
• Repeat serum potassium measurements every 2-4 hours until stable
• Continuous cardiac monitoring
• Serial arterial blood gases to assess acid-base status 1, 2

Special Considerations

• Cooling rate: Experts recommend cooling rates faster than 0.16°C/min, though rates above 0.08°C/min are considered acceptable 3
• Alternative cooling methods: Body bag cooling with water at 10°C achieves "ideal" cooling rates (0.18°C/min) and can be used when ice is limited 3
• Referral: For suspected malignant hyperthermia, refer patient and relatives to a regional MH center for further investigation 1

Pitfalls and Caveats

• Avoid overcooling: Stop active cooling once temperature drops below 38.5°C to prevent hypothermia
• Monitor glucose levels when administering insulin for hyperkalemia
• Don't delay treatment: The major determinant of outcome in heat stroke is the degree and duration of hyperthermia 4
• Be vigilant in vulnerable populations: Children, older adults, and those with chronic diseases are particularly susceptible to heat-related illnesses 5