Managing A Crisis

Emergency Treatment for An Acute MH Event

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

• Notify surgeon to halt the procedure ASAP: Discontinue volatile agents and succinylcholine.

–         If surgery must be continued, maintain general anesthesia with IV non-triggering anesthetics (e.g., IV sedatives, narcotics, amnestics and non-depolarizing neuromuscular blockers as needed)

• Get dantrolene/MH cart. (Call 911 if surgicenter)

–         Call for help within your institution; also, call the MHAUS Hotline (1-800-644-9737) for additional advice. (Outside the US, please call: 001-209-417-3722)

• Hyperventilate with 100% oxygen at flows of 10L/min to flush volatile anesthetics and lower ETCO2. If available, insert activated charcoal filters (Vapor-Clean^™, Dynasthetics, Salt Lake City, UT) into the inspiratory and expiratory limbs of the breathing circuit. The Vapor-Clean^™ filter may become saturated after one hour; therefore, a replacement set of filters should be substituted after each hour of use.
• 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.

–         DANTRIUM^®/REVONTO^® – Each 20 mg vial should be reconstituted by adding 60 ml of sterile water for injection, USP (without a bacteriostatic agent) and the vial shaken until the solution is clear.

–         RYANODEX^®– Each 250 mg vial should be reconstituted with 5 ml of sterile water for injection, USP (without a bacteriostatic agent) and shaken to ensure an orange-colored uniform, opaque suspension.

If giving large doses (> 10 mg/kg) without symptom resolution, consider alternative diagnoses.

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 

Cool the patient if core temperature is >39°C or less if rapidly rising. Stop cooling when the temperature has decreased to <38°C.

If hyperkalemia (K > 5.9 or less with ECG changes) is present, treat with:
 

• Calcium chloride 10 mg/kg (maximum dose 2,000 mg) or calcium gluconate 10-50 mg/kg (maximum dose 3,000 mg) for life-threatening hyperkalemia
• Sodium bicarbonate

–         1-2 mEq/kg IV 

• Glucose/insulin

–         For pediatric patients: 0.1 units regular insulin/kg IV and 2ml/kg of 25% dextrose (% in formulation not important)

–         For adult patients: 10 units regular insulin IV and 50 ml 50% dextrose

–         Check glucose levels hourly

For refractory hyperkalemia, consider albuterol (or other beta-agonist), dialysis, or ECMO if patient is in cardiac arrest.

Treat dysrhythmias with standard medication but avoid calcium channel blockers. Treat acidosis and hyperkalemia if present. (See above)

• 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

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.

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.

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