What is the treatment for hyperpyrexia?

Treatment of Hyperpyrexia

The treatment of hyperpyrexia requires immediate intervention with active cooling measures, administration of dantrolene in cases of malignant hyperthermia, and addressing the underlying cause to prevent mortality and reduce morbidity. 1

Diagnosis and Recognition

Early recognition is critical for successful management of hyperpyrexia:

• Hyperpyrexia is defined as a core body temperature of ≥106°F (41.1°C) 2
• In malignant hyperthermia (MH), cardinal clinical features include excessive carbon dioxide production, increased heart rate, and eventual muscle rigidity 1
• Unexplained increase in end-tidal CO2 despite increased minute ventilation is often the first sign of MH 1
• Temperature elevation may not be present early in MH but will rise rapidly if untreated 1

Treatment Algorithm for Hyperpyrexia

For Malignant Hyperthermia (Anesthesia-Related)

1. Eliminate triggering agents immediately 1:

   • Turn off and remove vaporizer
   • Deliver 100% oxygen at maximum flow
   • Increase minute ventilation 2-3 times normal
   • Insert activated charcoal filters on inspiratory and expiratory limbs of circuit

2. Administer dantrolene sodium 1:

   • Initial dose: 2-3 mg/kg IV
   • Titrate against effect
   • Traditional formulation: 20 mg vials reconstituted with 60 ml sterile water
   • Newer formulation (Ryanodex): 250 mg rapidly dissolved in 5 ml water (where available)

3. Initiate active body cooling 1:

   • Apply ice packs to groin, axillae, and neck
   • Cold IV fluids
   • Cooling blankets
   • Gastric, bladder, or peritoneal lavage with cold fluids if necessary

For Non-MH Hyperpyrexia (Post-Cardiac Arrest, Infection, Drug-Induced)

1. Implement active cooling measures 1:

   • Ice packs
   • Cooling blankets or pads
   • Cold IV fluids
   • Consider endovascular cooling devices in severe cases

2. Treat underlying cause 2, 3:

   • Administer broad-spectrum antibiotics if infection suspected (present in 94% of hyperpyrexia cases in one study) 2
   • Discontinue causative medications (e.g., MDMA, other stimulants) 4
   • Address neurologic causes (e.g., spinal cord injury-related "quad fever") 3, 5

3. Supportive care 1, 4:

   • Maintain adequate hydration
   • Monitor for and treat complications (rhabdomyolysis, metabolic acidosis, organ failure)
   • Consider ICU admission for close monitoring

Special Considerations

• Post-cardiac arrest patients: Treat hyperthermia aggressively as it is associated with worse neurological outcomes 1
• Drug-induced hyperthermia: Early administration of dantrolene may be beneficial even in non-MH cases (e.g., MDMA toxicity) 4
• Spinal cord injury: Consider "quad fever" in patients with spinal cord injuries who develop unexplained hyperpyrexia 3, 5

Monitoring and Follow-up

• Continuous core temperature monitoring is essential during treatment 1

• Monitor for complications of hyperpyrexia:

  • Rhabdomyolysis (check CK levels) 4, 6
  • Metabolic acidosis (arterial blood gases) 1, 4
  • Coagulopathy 1
  • Multi-organ failure 4, 5

• Patients with suspected MH and their relatives should be referred for specialized testing and genetic counseling 1, 6

Common Pitfalls to Avoid

• Delaying treatment while awaiting confirmation of diagnosis - early intervention is critical 1
• Failing to recognize MH because temperature has not yet risen significantly 1
• Inadequate dantrolene dosing - continue administration until symptoms resolve 1
• Not investigating for infection in non-anesthetic hyperpyrexia cases 2
• Failing to maintain cooling efforts until normothermia is achieved and stable 1