Malignant Hyperthermia (MH)

Trigger avoidance - No volatile agents and no succinylcholine. Run a total intravenous anesthetic (propofol) with a non-depolarizing relaxant; opioids, benzodiazepines, nitrous oxide, and regional techniques are all safe.

Prepare the machine - Use a vapor-free machine: remove or disable the vaporizers, change the CO2 absorbent and circuit, and flush with high-flow oxygen per your machine's protocol, or fit activated-charcoal filters.

Catch it early - An unexplained rise in end-tidal CO2 despite adequate ventilation is the earliest sign, along with tachycardia and masseter or generalized rigidity. Temperature rise is a late finding — don't wait for it.

Dantrolene - Treat a crisis with dantrolene 2.5 mg/kg IV, repeated every few minutes up to 10 mg/kg or more until the reaction abates. Know where your dantrolene is stocked before you need it.

Crisis management - Stop the trigger, hyperventilate with 100% oxygen at high flows, cool actively, treat hyperkalemia and arrhythmias, correct acidosis, push fluids, and watch for rhabdomyolysis and DIC. Call the MHAUS 24-hour MH Hotline at 1-800-644-9737 (in the US and Canada) for real-time guidance during a crisis.

Disposition - Monitor for at least 24 hours for recrudescence, then flag the chart and counsel the patient and family about future anesthetics.

Malignant hyperthermia (MH) is a hereditary skeletal-muscle disorder, most often from an RYR1 mutation, in which exposure to a volatile anesthetic or succinylcholine triggers uncontrolled calcium release from the sarcoplasmic reticulum.

The result is sustained muscle contraction and a hypermetabolic crisis: a rising end-tidal CO2, tachycardia, rigidity, and — later — hyperthermia, with rhabdomyolysis, hyperkalemia, and acidosis. It is typically inherited in an autosomal-dominant pattern, so a family history of an anesthetic catastrophe is a red flag.