Treatment of Hyperthermia
The immediate treatment of hyperthermia requires rapid identification of the cause, with malignant hyperthermia requiring dantrolene administration (2 mg/kg IV) and other forms of hyperthermia responding best to aggressive physical cooling methods rather than antipyretic medications. 1, 2
Types of Hyperthermia
Hyperthermia can be categorized into several distinct types, each requiring specific management:
- Malignant hyperthermia (MH): A life-threatening genetic disorder triggered by volatile anesthetic agents and succinylcholine 1
- Drug-induced hyperthermia: Caused by sympathomimetics, antidopaminergics, anticholinergics, and serotonergic agents 3
- Environmental/exertional hyperthermia: Results from excessive heat production or inadequate heat dissipation 2
- Infectious fever: A regulated rise in temperature (differs from true hyperthermia) 2
Treatment Algorithm for Malignant Hyperthermia
Immediate Actions
- Stop all trigger agents (volatile anesthetics and succinylcholine) 1
- Hyperventilate with 100% oxygen at high flow (2-3 times normal minute volume) 1
- Declare emergency and call for help 1
- Switch to non-triggering anesthesia (TIVA) if anesthesia must continue 1
- Inform surgeon and request termination/postponement of surgery 1
Dantrolene Administration
- Give dantrolene 2 mg/kg IV (20 mg ampoules mixed with 60 ml sterile water) 1
- Obtain additional dantrolene from pharmacy/nearby hospitals (36-50 ampoules may be needed for an adult) 1
- Repeat dantrolene infusions until cardiorespiratory stabilization 1
- Maximum dose may exceed 10 mg/kg if necessary 1
Cooling Measures
- Administer 2000-3000 ml of chilled (4°C) 0.9% saline IV 1
- Apply surface cooling: wet cold sheets, fans, ice packs in axillae and groin 1
- Utilize other cooling devices if available 1
- Discontinue cooling once temperature falls below 38.5°C 1
Management of Complications
- Hyperkalemia: Administer 50 ml of 50% dextrose with 50 IU insulin (adult dose) and calcium chloride 0.1 mmol/kg IV 1
- Acidosis: Hyperventilate to normocapnea and give sodium bicarbonate IV if pH < 7.2 1
- Arrhythmias: Administer amiodarone 300 mg (3 mg/kg IV) and consider beta-blockers if tachycardia persists 1
- Maintain urine output > 2 ml/kg/h: Use furosemide 0.5-1 mg/kg, mannitol 1 g/kg, and crystalloid fluids 1
Treatment of Non-Malignant Hyperthermia
Physical Cooling Methods (Most Effective)
- Methods involving convection and evaporation are more effective than conduction for hyperthermia 4, 5
- Avoid tepid sponging and ice packs alone as they may induce shivering and vasoconstriction 5
- Whole-body cooling is the only effective treatment for non-febrile hyperthermia 2
Pharmacological Interventions
- Antipyretic medications are ineffective for true hyperthermia (only work for fever) 2
- For drug-induced hyperthermia, specific antidotes may be required based on the causative agent 3
Monitoring and Supportive Care
- Continuous monitoring of core temperature, vital signs, and organ function 1, 5
- Aggressive fluid resuscitation to prevent renal failure from rhabdomyolysis 3
- Monitor for electrolyte disturbances, particularly hyperkalemia 1
Special Considerations
- Patients with suspected malignant hyperthermia should be referred to specialized MH investigation units for diagnostic testing 1
- In-vitro contracture testing (IVCT) is the standard for diagnosing MH susceptibility 1
- Action cards adapted for local conditions can be extremely helpful in managing MH crises 1
- For localized hyperthermia treatments (e.g., for HPV infections), controlled local heating has shown therapeutic benefits 6
Common Pitfalls to Avoid
- Do not waste time changing the anesthetic circuit/machine during an MH crisis - disconnect the vaporizer immediately 1
- Do not confuse fever with hyperthermia - they require different treatment approaches 2
- Do not rely on antipyretics for true hyperthermia as they will be ineffective 2
- Do not delay dantrolene administration when MH is suspected - early treatment is critical 1