What is malignant hyperthermia, how does it present intraoperatively, and what is the treatment?

• A. Hypercarbia, tachycardia, hyperthermia, muscle rigidity; treat with dantrolene, stop triggering agents, cool patient, supportive care.
• B. Hypoglycemia treatment.
• C. Allergic reaction to latex.
• D. Infection and fever due to poor asepsis.

Answer: (A)

Malignant hyperthermia is an acute, life-threatening reaction in susceptible patients triggered by certain anesthetic agents, causing a hypermetabolic state in skeletal muscle. The underlying problem is excessive calcium release from the sarcoplasmic reticulum, driven by a genetic predisposition, which leads to sustained muscle contraction, heat production, and rapid metabolic collapse if not treated.

Intraoperatively, the hallmark is a sudden rise in end-tidal CO2 despite adequate ventilation, often accompanied by tachycardia and muscle rigidity. Hyperthermia tends to occur later but can develop quickly as the crisis progresses. Other signs can include metabolic acidosis and electrolyte disturbances, especially hyperkalemia, and signs of rhabdomyolysis if not controlled.

The treatment focuses on removing the trigger and halting the hypermetabolic process. Stop the triggering anesthetic agents and switch to non-triggering anesthesia, then administer dantrolene promptly to block calcium release from the sarcoplasmic reticulum. Supportive measures are crucial: aggressively ventilate with 100% oxygen, actively cool the patient, correct acid-base and electrolyte disturbances, maintain good urine output to protect the kidneys, and provide continued monitoring and ICU-level care as the crisis is controlled and resolves.

Other options don’t fit this scenario because hypoglycemia, latex allergy, and infection-related fever have different clinical pictures and timing.