Clinical Tools

Malignant Hyperthermia

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Hotline: 1-800-644-9737

Call for Help

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Call for help. Announce "Malignant Hyperthermia". Call MHAUS Hotline: 1-800-644-9737.

1-800-644-9737

Discontinue Triggering Agents

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Discontinue all volatile agents and succinylcholine immediately.

Hyperventilate with 100% O2

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Hyperventilate with 100% O2 at high fresh gas flows (10+ L/min). Do NOT change the anesthesia machine or circuit.

Administer Dantrolene

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Dantrolene 2.5 mg/kg IV bolus. Repeat every 5 minutes until symptoms resolve. There is no upper limit.

Dantrolene (Dantrium)

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Repeat every 5 min until symptoms resolve. No upper limit.

Reconstitution: Dantrium: 20 mg/vial, reconstitute with 60 mL preservative-free sterile water.

Dantrolene (Ryanodex)

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Repeat every 5 min until symptoms resolve. No upper limit.

Reconstitution: Ryanodex: 250 mg/vial, reconstitute with 5 mL preservative-free sterile water.

Treat Hyperkalemia

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Treat hyperkalemia aggressively with calcium chloride, sodium bicarbonate, insulin with glucose, and hyperventilation.

Calcium Chloride 10%

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For cardiac stabilization from hyperkalemia.

Sodium Bicarbonate

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1-2 mEq/kg IV. Drives potassium intracellularly.

Regular Insulin

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Co-administer with glucose 0.5 g/kg.

Glucose (Dextrose)

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Co-administer with insulin 0.1 units/kg.

Active Cooling

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Active cooling: cold IV normal saline, ice packs to axillae and groin, body cavity lavage if abdomen/thorax open. Stop cooling measures at 38 degrees C to avoid overshoot hypothermia.

Treat Arrhythmias

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Treat arrhythmias with amiodarone or lidocaine. Do NOT use calcium channel blockers -- combination with dantrolene may cause fatal hyperkalemia and cardiovascular collapse.

Monitor Labs and Vitals

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Monitor: arterial blood gas (ABG), potassium (K+), creatine kinase (CK), myoglobin (serum and urine), core temperature (continuously), and urine output.

Maintain Urine Output

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Maintain urine output at least 2 mL/kg/hr with IV fluids and mannitol or furosemide to prevent myoglobin-induced renal failure.

Post-Crisis Dantrolene and ICU

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Continue dantrolene 1 mg/kg IV every 4-6 hours for at least 24 hours. ICU monitoring for 36+ hours. Monitor for recrudescence (25% of cases).

Source: MHAUS Emergency Protocol

Limitations

  • This protocol is a reference aid and does not replace clinical judgment.
  • Dantrolene reconstitution is time-consuming and requires multiple personnel.
  • Clinical presentation may be atypical or overlap with other conditions (e.g., sepsis, thyroid storm, pheochromocytoma).
  • End-tidal CO2 rise may be the earliest sign but is not specific to MH.

References

  1. Malignant Hyperthermia Association of the United States (MHAUS). Emergency Therapy for Malignant Hyperthermia. https://www.mhaus.org
  2. Rosenberg H, et al. Malignant hyperthermia management - 2019 guideline. Anaesthesia. 2019;74(3):373-384.
  3. Hopkins PM, et al. European Malignant Hyperthermia Group guidelines for investigation of malignant hyperthermia susceptibility. Br J Anaesth. 2015;115(4):531-539.