Malignant Hyperthermia

Abstract

Malignant hyperthermia (MH) is a rare, genetically inherited hypermetabolic syndrome that remains dormant until triggered by exposure to certain conditions (emotional and physical stresses) or pharmacological agents (anesthetic gases and succinylcholine) in susceptible individuals. It is believed that MH is caused by a derangement in the control of intracellular calcium ions, which results in a hypermetabolic state from sustained muscle contractures. Without supportive measures and immediate treatment with the antidote, dantrolene, the mortality rate from MH can be as high as 70%. A complete personal and family medical history before surgery can show important clues that might alter the anesthetic regimen preoperatively and postoperatively (eg, the use of nontriggering agents) in MH-susceptible patients. Anesthesia personnel need to recognize the early signs of a MH crisis (eg, tachycardia, muscle stiffness, hypercapnia, and tachypnea), then monitor for other signs (eg, arrhythmias, blood pressure changes, fever, metabolic and respiratory acidosis, and mottling cyanosis), and initiate prompt treatment. Because immediate recognition and treatment of this potentially fatal hyperpyrexic episode increase a patient's chance of survival, other health care personnel (eg, nurses, pharmacists) play key roles in the emergency treatment of a MH crisis. A suspected episode of MH should be followed up with contracture testing to determine MH susceptibility (MHS). Reports of MH should be reported to the North American MH Registry.