Malignant hyperthermia rapid overview of emergency management

Clinical signs*

Hypercarbia (elevated ETCO₂) resistant to increases in minute ventilation

Tachypnea or breathing over the ventilator

Sinus tachycardia

Masseter spasm with or without administration of succinylcholine

Generalized muscle rigidity

Peaked T waves or other arrhythmia (including PVCs, ventricular tachycardia or fibrillation) as a result of hyperkalemia

Mixed acidosis on blood gas

Hyperthermia

Sweating

Management

Call for help and MH cart; for questions at any time call MH hotline: 1-800-644-9737 in US, 1-209-417-3722 outside US

Discontinue inhaled anesthetics and succinylcholine; increase fresh gas flow to ≥ 10 L/minute, use non-triggering agents for remainder of procedure

Notify surgeon; complete surgical procedure as quickly as possible

Hyperventilate with 100% oxygen, perform endotracheal intubation if ETT not in place

Insert carbon filters into breathing circuit after flushing the breathing circuit for ≥90 seconds at ≥10 L/minute fresh gas flow

Administer dantrolene:

Initial dose 2.5 mg/kg IV rapid bolus; eg, for a 70 kg patient, administer 175 mg IV

For older dantrolene preparations (ie, Dantrium, Renovo, or dantrolene sodium), dilute each 20 mg vial with 60 mL sterile preservative-free water; eg, for 70 kg patient, prepare nine 20 mg vials

For Ryanodex, dilute a 250 mg vial with 5 mL sterile preservative-free water

Watch for reversal of clinical signs (ETCO₂ should begin to normalize); repeat dantrolene bolus (2.5 mg/kg IV) as necessary; cumulative doses ≥10 mg/kg IV may be required

Send laboratory studies: venous or arterial blood gases, electrolytes, CK; repeat as necessary

Treat hyperkalemia in patients with arrhythmias or potassium >6 mEq/L

Calcium:

Calcium chloride

Adult: 0.5 to 1 g IV (5 to 10 mL of 10% solution) per dose;

Pediatric: 10 to 20 mg/kg IV (0.1 to 0.2 mL/kg 10% solution), maximum 2 g (20 mL) per dose

Repeat after five minutes if ECG changes persist

Calcium gluconate

Adult: 1.5 to 3 g IV (15 to 30 mL of 10% solution);

Pediatric: 60 to 100 mg/kg IV (0.6 to 1 mL/kg of 10% solution), maximum 3 g (30 mL) per dose

Sodium bicarbonate: 1 to 2 mEq/kg IV push over 5 to 10 minutes (maximum 100 mEq per dose); do not administer sodium bicarbonate in the same line as calcium

Insulin and dextrose: check blood glucose hourly

Adult: 10 units IV regular insulin IV push with 50 mL IV 50% dextrose

Pediatric: 0.1 units/kg insulin IV push with 0.5 g/kg dextrose (eg, 1 mL/kg 50% dextrose or 2 mL/kg 25% dextrose)

Treat metabolic acidosis with base deficit ≥8 mEq/L with sodium bicarbonate 1 to 2 mEq/kg IV over 5 to 10 minutes, maximum 100 mEq per dose.

Treat arrhythmias per ACLS, avoid calcium channel blockers; most arrhythmias respond to correction of hyperkalemia and acidosis

Cool the patient as necessary: Start cooling for core temperature >39°C, discontinue cooling when temperature decreases to 38°C

Insert Foley catheter, maintain urine output at 1 to 2 mL/kg/hour with IV fluid and diuretics

Ongoing care

Arrange ICU bed for at least 24 hours; monitor for recurrence, rhabdomyolysis, DIC

After initial MH event is controlled, administer dantrolene 1 mg/kg IV every four to six hours or 0.25 mg/kg/hour for at least 24 hours

For further information, refer to UpToDate content on management of an acute MH crisis.

ETCO₂: end-tidal carbon dioxide; PVCs: premature ventricular contractions; MH: malignant hyperthermia; ETT: endotracheal tube; IV: intravenous; CK: creatine kinase; ECG: electrocardiogram; ACLS: advanced cardiac life support; ICU: intensive care unit; DIC: disseminated intravascular coagulation.

* The sequence and timing of the clinical manifestations of MH vary from patient to patient, and most patients do not develop all signs of MH.

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Malignant hyperthermia rapid overview of emergency management