What is the cornerstone drug and initial steps in the treatment of malignant hyperthermia?

• A. Stop triggering agents, administer 100% O2, and give dantrolene promptly (2.5 mg/kg IV initial; repeat as needed), with rapid cooling and correction of metabolic derangements.
• B. Increase inhaled anesthetic concentration to suppress metabolic demand.
• C. Administer epinephrine and monitor body temperature.
• D. Use benzodiazepines as the sole treatment.

Answer: (A)

In malignant hyperthermia, the crisis is driven by a sudden, uncontrolled release of calcium in skeletal muscle that ramps up metabolism and heat production. The fastest, most effective way to interrupt this process is to stop all triggering agents, provide 100% oxygen, and give dantrolene promptly. Dantrolene works by inhibiting the ryanodine receptor on the sarcoplasmic reticulum in skeletal muscle, which prevents calcium from leaking out and dramatically reduces muscle rigidity, heat generation, and the whole hypermetabolic state. The initial dose is 2.5 mg/kg IV, with repeat dosing as needed to control the crisis, and the total amount may reach around 10 mg/kg or more depending on severity. Alongside the drug, rapid cooling and aggressive management of metabolic problems—acidosis, electrolyte disturbances, and potential rhabdomyolysis—are essential.

Stopping the triggering agents and giving high-concentration oxygen target the root cause and provide supportive care. Increasing the inhaled anesthetic concentration would worsen the problem by continuing to stimulate the malignant process. Epinephrine is not the primary treatment for MH and can complicate the situation, while benzodiazepines alone do not address the underlying calcium dysregulation.