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Managing An MH Crisis

Emergency Treatment for An Acute MH Event

  1. The following four things should be done as soon as possible:

    1. Discontinue volatile agents and succinylcholine. If surgery must be continued, maintain general anesthesia with IV nontriggering anesthetics (eg, propofol).
    2. Notify surgeon to halt procedure ASAP.
    3. Get dantrolene/MH cart. (Call 911 if surgicenter.)
    4. Call for help within your institution; also, call the MHAUS Hotline (1-800-644-9737) for additional advice. (Outside the US, please call: 00+1+209+417+3722)
  2. Hyperventilate with 100% oxygen at flows of 10L/min to flush volatile anesthetics and lower ETCO2. If available, insert activated charcoal filters into the inspiratory and expiratory limbs of the breathing circuit.
  3. Give IV dantrolene 2.5 mg/kg rapidly through large-bore IV, if possible. Repeat as frequently as needed until the patient responds with a decrease in ETCO2, decreased muscle rigidity, and/or lowered heart rate. Large doses (>10mg/kg) may be required for patients with persistent contractures or rigidity.

    • Each vial of dantrolene (20 mg) should be diluted with at least 60 ml of sterile, preservative-free water. Shake well.
    • If giving large doses (> 10 mg/kg) without symptom resolution, consider alternative diagnoses.
  4. Obtain blood gas (venous or arterial) to determine degree of metabolic acidosis. Consider administration of sodium bicarbonate, 1-2 mEq/kg dose, for base excess greater than -8 (maximum dose 50 mEq).
  5. Cool the patient if core temperature is >39°C or less if rapidly rising. Stop cooling when the temperature has decreased to <38°C.
  6. If hyperkalemia (K > 5.9 or less with ECG changes) is present, treat with bicarbonate, glucose/insulin and calcium:

    • For pediatric patients: 0.1 units regular insulin/kg IV and 0.5 Grams/kg dextrose (% in formulation not important).
    • For adult patients: 10 units regular insulin IV and 50 ml 50% glucose.
    • Calcium chloride 10 mg/kg (maximum dose 2,000 mg) or calcium gluconate 30 mg/kg (maximum dose 3,000 mg) for life-threatening hyperkalemia.
    • Check glucose levels hourly.
    • Sodium bicarbonate 1-2 mEq/kg IV (maximum dose 50 mEq)
    • Furosemide 0.5-1 mg/kg once (maximum dose 20 mg)
    • For refractory hyperkalemia, consider albuterol (or other beta-agonist), kayexelate, dialysis, or ECMO if patient is in cardiac arrest.
  7. Treat dysrhythmias with standard medication but avoid calcium channel blockers. Treat acidosis and hyperkalemia if present. (See numbers 4 and 6.)
  8. Diurese to >1ml/kg/hr urine output. If CK or K+ rise, assume myoglobinuria and give bicarbonate infusion of 1 mEq/kg/hr, to alkalinize urine.
  9. Institute appropriate monitoring including: core temperature, urine output with bladder catheter, and consider arterial and/or central venous monitoring if warranted by the clinical severity of the patient.
  10. Follow: HR, core temperature, ETCO2, minute ventilation, blood gases, K+, CK, urine myoglobin and coagulation studies as warranted by the clinical severity of the patient.
  11. When stable, transfer to post anesthesia care unit or intensive care unit for at least 24 hours. Key indicators of stability include:

    • ETCO2 is declining or normal.
    • Heart rate is stable or decreasing with no signs of ominous dysrhythmias.
    • Hyperthermia is resolving.
    • If present, generalized muscular rigidity has resolved.

MH Crisis Resources