Which agents are classic triggers for malignant hyperthermia, and the first-line pharmacologic treatment?

• A. Volatile inhaled anesthetics and succinylcholine; treat with dantrolene
• B. Propofol and fentanyl; treat with cooling
• C. Ketamine and midazolam; treat with cooling
• D. Nitrous oxide and morphine; treat with beta-blocker

Answer: (A)

Malignant hyperthermia is a geneticly mediated skeletal muscle calcium regulation problem that can be precipitated by certain anesthesia drugs. The classic triggers are volatile inhaled anesthetics and the depolarizing muscle relaxant succinylcholine. When these agents are used, calcium floods the muscle cells, driving a rapid, uncontrolled metabolic crisis with increased CO2 production, heat, acidosis, and potential rhabdomyolysis if not treated quickly. The first-line pharmacologic treatment is dantrolene, which works by blocking calcium release from the sarcoplasmic reticulum through its action on the ryanodine receptor, effectively halting the hypermetabolic process. Immediate steps also include stopping triggering agents, providing 100% oxygen, and aggressively cooling and correcting electrolyte and acid-base disturbances. The other pairings listed do not represent typical triggers for malignant hyperthermia, and cooling alone is supportive rather than the specific first-line drug therapy.