Malignant Hyperthermia

Every now and then (quite rarely), when a pt is given a GA (also has been associated with the use of succinyl choline with the anesthetic) the sarcoplasmic reticulum in the skeletal muscle cells become leaky.

This is a genetic condition. Calcium thus leaks out of the sarcoplasmic reticulum causes massive contraction and the calcium ATPases in the sarcoplasmic reticulum to turn on, full-speed. They do this and generate and enormous amount of heat. So the incidence in the US is 1 in 50,000 adults and 1 in 15,000 kids.

The treatment for MH is to immediately cease whatever operation is being done, MH is an emergency of the first order! Stop administration of anesthetic and hyperventilate the pt with 100% oxygen. Give intravenous dantrolene, which can plug the sarcoplasmic reticulum and reduce the calcium leakage. Then, you’ve got to do everything possible to fight the hyperthermia. Put the pt in ice, inject cold IV saline, lavage all body cavities with ice-water, and pray… often times the pt won’t make it. This can rarely occur with use of nitrous oxide!!! So we must be aware of this possibility.

You should be able to get an idea from the pt’s med history if they or their family is prone to this malignant hyperthermia.

Category: Pharmacology Notes