As anesthetic complications go, malignant hyperthermia is rare, but it's potentially fatal. It's possible to screen patients who report a family history of MH (it's inherited) and to prevent it by avoiding triggering agents, especially in patients who are known to be susceptible (see "Screening for MH"). But suppose that a patient whose operative history doesn't indicate susceptibility appears to be having an MH episode. Is it MH? Here are three real cases reported to the MH Hotline (800-MH-HYPER) to test your knowledge of the signs and symptoms of the complication.