Malignant hyperthermia during anesthesia is most characteristically indicated by which finding?

• A. Severe hypotension and bradycardia
• B. Muscle rigidity with hypercarbia during anesthesia
• C. Hyperglycemia and polyuria
• D. Jaundice and hepatic failure

Answer: (C)

Malignant hyperthermia is a genetic reaction in skeletal muscle triggered by certain anesthetics and depolarizing agents, causing uncontrolled calcium release and a hypermetabolic state. The hallmark during anesthesia is muscle rigidity accompanied by hypercarbia—an abrupt rise in end-tidal CO2 despite ventilation. This increased CO2 reflects the enormous metabolic activity from sustained muscle contraction. Other signs like tachycardia may appear, and hyperthermia can develop later, but the combination of rigid muscles with rising CO2 is the most characteristic early indicator. Hyperglycemia and polyuria, or jaundice and hepatic failure, are not classic acute features of MH. Immediate management focuses on stopping triggering agents, administering dantrolene, increasing 100% oxygen ventilation, and cooling and supporting the patient.