What is the treatment for malignant hyperthermia?

Treatment of Malignant Hyperthermia

The treatment of malignant hyperthermia requires immediate administration of dantrolene sodium (2-3 mg/kg IV initially) along with discontinuation of triggering agents, hyperventilation with 100% oxygen, and active cooling measures to reduce mortality. 1, 2

Immediate Actions

1. Stop all triggering agents:

   • Discontinue volatile anesthetics and succinylcholine
   • Remove vaporizer from anesthetic machine
   • Hyperventilate with 100% oxygen at high flow (2-3 times normal minute ventilation)
   • Insert activated charcoal filters on inspiratory and expiratory limbs of circuit if available 1
   • Switch to non-triggering anesthesia (TIVA) if anesthesia must continue 1

2. Declare emergency and call for help

   • Inform surgeon and request termination/postponement of surgery 1

Dantrolene Administration

1. Initial dosing:

   • Administer dantrolene 2-3 mg/kg IV based on actual body weight 1, 2
   • Each 20 mg vial requires reconstitution with 60 ml sterile water
   • Administer each syringe as soon as it's prepared rather than waiting for complete dose 1, 2

2. Continued treatment:

   • Continue giving additional doses of 1 mg/kg until treatment goals are achieved 1
   • Treatment goals:
     • ETCO₂ < 6 kPa with normal minute ventilation
     • Core temperature < 38.5°C
     • Stabilization of heart rate and resolution of muscle rigidity 2
   • The maximum dose (10 mg/kg) may need to be exceeded in severe cases 1

Monitoring and Supportive Care

1. Establish monitoring:

   • Core temperature measurement
   • Arterial blood pressure monitoring (consider arterial line)
   • Central venous access if needed
   • Urinary catheter placement 1

2. Laboratory monitoring:

   • Arterial blood gases
   • Electrolytes (especially potassium)
   • Creatine kinase (CK)
   • Myoglobin
   • Coagulation studies 1

Management of Complications

1. Hyperthermia:

   • Administer 2000-3000 ml of chilled (4°C) 0.9% saline IV
   • Apply surface cooling: wet cold sheets, fans, ice packs in axillae and groin
   • Stop cooling once temperature < 38.5°C 1

2. Acidosis:

   • Hyperventilate to normocapnia
   • Administer sodium bicarbonate IV if pH < 7.2 1

3. Hyperkalaemia:

   • Administer glucose (50 ml of 50% solution) with insulin (50 IU) for adults
   • Consider sodium bicarbonate
   • Use calcium chloride (0.1 mmol/kg IV) only in extreme cases 1
   • Consider dialysis if severe and unresponsive 1

4. Arrhythmias:

   • Treat tachyarrhythmias with amiodarone (300 mg for adults, 3 mg/kg IV)
   • Consider beta-blockers if tachycardia persists 1

5. Myoglobinuria:

   • Maintain urine output > 2 ml/kg/h
   • Consider furosemide (0.5-1 mg/kg)
   • Consider mannitol (1 g/kg)
   • Administer IV fluids (crystalloids) 1
   • Consider sodium bicarbonate for urine alkalinization 1

6. Disseminated intravascular coagulopathy:

   • Treat empirically with platelets, fresh frozen plasma, and cryoprecipitate
   • Note that tranexamic acid is not indicated 1

7. Compartment syndrome:

   • Monitor for development, especially in patients with myoglobinuria
   • Perform regular assessment of limbs for swelling, muscle softness, peripheral pulses
   • Measure compartmental pressures if suspected
   • Treat with fasciotomies if confirmed 1

Post-Crisis Management

1. Monitoring period:

   • Monitor patient for minimum of 24 hours (ICU/HDU)
   • If dantrolene was required, monitor in ICU for at least 24 hours 1
   • Watch for recrudescence, which can occur up to 14 hours after initial control 1

2. Recrudescence management:

   • If recrudescence occurs within 6 hours of initial treatment, give 1 mg/kg dantrolene
   • If more than 6 hours since previous dose, give 2-3 mg/kg 1, 2
   • Do not use continuous infusion of dantrolene due to risk of thrombophlebitis 1, 2

Important Caveats

1. Calcium administration: Intravenous calcium should only be used in extreme cases of hyperkalaemia as it may worsen calcium overload in muscle cells 1

2. Dantrolene availability: Ensure adequate supply - at least 36 vials (720 mg) should be immediately available with additional 24 vials accessible within 1 hour 2

3. Side effects of dantrolene: Be aware of potential muscle weakness, visual symptoms, dizziness, fatigue, and thrombophlebitis 2, 3

4. Patient and family counseling: Before discharge, inform patient and family about the suspected diagnosis and its implications for future anesthetic management 1

5. Referral: Refer patients with suspected MH to regional or national MH centers for further investigation and genetic testing 1