Malignant Hyperthermia: Immediate Life-Saving Management
The moment malignant hyperthermia is suspected, immediately stop all volatile anesthetics and succinylcholine, hyperventilate with 100% oxygen at 2-3 times normal minute volume, and administer intravenous dantrolene 2 mg/kg as the definitive life-saving treatment. 1
Immediate Actions (First 60 Seconds)
Stop all trigger agents immediately - discontinue all volatile anesthetics (sevoflurane, desflurane, isoflurane, halothane) and succinylcholine without delay. 1
Hyperventilate aggressively - increase minute ventilation to 2-3 times normal using 100% oxygen at maximum flow rates to combat the hypermetabolic state and eliminate CO2. 1
Declare an emergency and mobilize help - call for additional personnel immediately as managing MH requires multiple hands for dantrolene preparation and patient care. 1
Switch to non-trigger anesthesia - convert to total intravenous anesthesia (TIVA) with propofol or other non-triggering agents. 1
Notify the surgeon - request immediate termination or postponement of surgery to focus on resuscitation. 1
Disconnect the vaporizer - remove it from the circuit but do not waste precious time changing the entire anesthesia machine or breathing circuit during the acute crisis. 1
Definitive Treatment: Dantrolene Administration
Administer dantrolene 2 mg/kg intravenously immediately - this is the only specific antidote and cornerstone of successful MH treatment. 1, 2 Each 20 mg vial must be mixed with 60 ml of sterile water. 1
Prepare for massive dantrolene requirements - obtain at least 36-50 vials for an adult patient from pharmacy or nearby hospitals, as large cumulative doses are often needed. 1
Repeat dantrolene infusions - continue administering dantrolene until cardiac and respiratory systems stabilize, even if this requires exceeding the traditional maximum dose of 10 mg/kg. 1 The priority is patient survival, not arbitrary dose limits.
Critical Monitoring and Supportive Care
Establish robust vascular access - insert wide-bore intravenous cannulas for rapid medication and fluid administration. 1
Measure core temperature continuously - hyperthermia is a late sign but requires aggressive treatment once present. 1
Obtain urgent laboratory studies - draw blood for potassium, creatine kinase, arterial blood gases, myoglobin, and glucose to assess the severity of the hypermetabolic crisis. 1
Consider invasive monitoring - place arterial and central venous lines for continuous hemodynamic assessment and a urinary catheter to monitor renal function. 1
Continue standard anesthetic monitoring - maintain pulse oximetry, ECG, non-invasive blood pressure, and end-tidal CO2 monitoring throughout. 1
Treatment of Specific Complications
Hyperthermia Management
Administer chilled intravenous fluids - infuse 2000-3000 ml of cold (4°C) 0.9% saline intravenously. 1
Apply aggressive surface cooling - use wet cold sheets, fans, and ice packs in the axillae and groin. 1
Stop cooling at 38.5°C - avoid overcorrection and hypothermia. 1
Hyperkalemia Treatment
Give dextrose and insulin - administer 50 ml of 50% dextrose with 50 units of insulin (adult dose) to drive potassium intracellularly. 1
Administer calcium chloride - give 0.1 mmol/kg IV (approximately 7 mmol or 10 ml for a 70 kg adult) to stabilize cardiac membranes. 1
Prepare for dialysis - severe hyperkalemia may require emergent hemodialysis if refractory to medical management. 1
Acidosis Correction
Hyperventilate to normocapnia - aggressive ventilation is the primary treatment for respiratory acidosis. 1
Give sodium bicarbonate if pH < 7.2 - administer intravenously for severe metabolic acidosis. 1
Arrhythmia Management
Use amiodarone for ventricular arrhythmias - give 300 mg IV for adults (3 mg/kg). 1
Administer beta-blockers for persistent tachycardia - propranolol, metoprolol, or esmolol can be used if heart rate remains elevated. 1
Renal Protection
Maintain urine output > 2 ml/kg/hour - this prevents myoglobin-induced acute kidney injury from rhabdomyolysis. 1
Give furosemide 0.5-1 mg/kg - promote diuresis to clear myoglobin. 1
Administer mannitol 1 g/kg - osmotic diuresis helps protect renal function. 1
Infuse crystalloid fluids liberally - use lactated Ringer's solution or 0.9% saline to maintain intravascular volume. 1
Post-Crisis Management
Monitor for a minimum of 24 hours - admit to ICU, high-dependency unit, or recovery room with continuous observation as recrudescence can occur. 1, 3
Check for compartment syndrome - examine for signs of muscle swelling and neurovascular compromise from rhabdomyolysis. 1
Monitor renal and hepatic function - assess for organ damage from the hypermetabolic crisis. 1
Evaluate coagulation status - check for disseminated intravascular coagulation. 1
Critical Pitfalls to Avoid
Do not delay dantrolene administration - waiting for diagnostic confirmation or complete laboratory results is a fatal error; treat on clinical suspicion. 4, 5, 6 The European Malignant Hyperthermia Group emphasizes that early recognition and immediate treatment are essential for patient survival. 1
Do not assume previous uneventful anesthetics exclude MH - patients can have multiple uncomplicated exposures to triggering agents before experiencing an MH crisis. 1, 4
Do not use calcium channel blockers - these may interfere with dantrolene and cause cardiovascular collapse. 5
Do not underestimate dantrolene requirements - be prepared to exceed 10 mg/kg if the patient does not stabilize. 1
Recognize masseter spasm as a warning sign - jaw muscle rigidity after succinylcholine may be the first indication of developing MH and should trigger immediate vigilance and preparation. 1, 2, 7