The initial sign to monitor for malignant hyperthermia in patients receiving anesthesia is which?

• A. Tachycardia
• B. Hypertension
• C. Hypothermia
• D. Hypotension

Answer: (A)

In malignant hyperthermia, the first clue during anesthesia is a rapid rise in heart rate. This tachycardia occurs as the triggered muscles suddenly go into a hypermetabolic state, increasing oxygen use and carbon dioxide production and triggering sympathetic stimulation. It usually appears before overt changes in blood pressure or body temperature. Hypertension and hypotension aren’t the earliest, and hypothermia would be opposite to what MH causes. As the crisis progresses, other signs like rising end-tidal CO2, muscle rigidity, and eventually hyperthermia may develop, but tachycardia is the earliest warning sign clinicians monitor.