Malignant hyperthermia (MH) is a chain-reaction event triggered in susceptible individuals by commonly used general anesthetics. The signs of MH include a greatly increased body metabolism, muscle rigidity and eventual hyperthermia which may exceed 43 C. Death can result from heart attack, brain damage, internal hemorrhaging, or failure of other body systems.
Susceptibility to MH is diagnosed by muscle biopsy. A rapid and reliable test for MH would be beneficial to anaesthetists, as screening for mutations of the RYR1 gene detects only 20-40% of susceptible families. Martin Anetseder and colleagues from the University of Wrzburg, Germany, proposed that intramuscular injection of caffeine would increase local carbon dioxide pressure in individuals susceptible to MH.
After localised caffeine stimulation, carbon dioxide pressure was measured in the buttock muscle in 12 patients susceptible to MH, eight known not to be susceptible, and seven healthy individuals (the control group). Carbon dioxide pressure increased temporarily (to 63 mm Hg) in susceptible individuals compared with 44 mm Hg in non-susceptible participants, and 42 mm Hg in the control group.
Martin Anetseder comments: Despite these encouraging findings, large numbers in a multicentre trial are needed to define sensitivity and specificity before this test can allow a definite diagnosis of susceptibility to malignant hyperthermia.