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Anesthesia: Malignant Hyperthermia Response

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Malignant hyperthermia is a rare, inherited (genetic) disorder that is potentially fatal. It can be triggered by exposure to certain anesthetics, particularly the potent inhalation anesthetics and by succinylcholine (Anectine and Quelicin), a muscle relaxant.

The disorder is caused by too-rapid metabolism by the cells of certain skeletal muscle tissue that leads to a breakdown of these muscles. Signs of malignant hyperthermia include increased carbon dioxide in the blood and lungs and increased blood pressure, heart rate, and breathing. A rapid increase in body temperature (hyperthermia) is frequently a late sign. If untreated, malignant hyperthermia is usually fatal.

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When triggered by anesthesia, malignant hyperthermia typically occurs shortly after anesthesia is first given. But it can occur at any time during anesthesia or in rare cases may occur as late as 24 hours after surgery.

Malignant hyperthermia is very rare. But you may be at an increased chance of getting it if:

  • You have a medical history that suggests you had malignant hyperthermia before.
  • Someone in your family has a medical history that suggests he or she had this condition before.
  • You have rare conditions or other diseases that affect the muscles.

You can have a test to help find out if you have an increased chance of malignant hyperthermia.

People at risk of malignant hyperthermia may have a family history of unexplained death during anesthesia, an unexpected serious complication during anesthesia, breakdown of muscle tissue during exercise, muscle disorders, heatstroke, or heat intolerance.

Treatment for malignant hyperthermia includes discontinuing the anesthesia immediately, giving the person 100% oxygen to breathe, and administering the medicine dantrolene. The person usually needs to continue receiving dantrolene for 12 to 48 hours and needs to be closely watched in an intensive care unit.

If a person who is at possible risk of malignant hyperthermia needs anesthesia, the condition can be safely and completely avoided by choosing anesthetic agents that do not trigger malignant hyperthermia.

You can get more information about malignant hyperthermia from the Malignant Hyperthermia Association of the United States (MHAUS). Go to the website at


WebMD Medical Reference from Healthwise

Last Updated: September 30, 2011
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.
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