Markedly delayed postoperative malignant hyperthermia.

Malignant hyperthermia (MH) may be triggered by exposure to commonly employed anesthetic agents and muscle relaxants, and often manifests itself during the period of anesthesia. Delayed-onset MH occurring one to four hours postoperatively has been described in isolated case reports. A case of delayed-onset MH occurred 11 hours following routine tonsillectomy and adenoidectomy. The patient demonstrated tachypnea, tachycardia, hyperthermia, and metabolic acidosis. Prompt intravenous administration of dantrolene sodium was therapeutic. Serial serum creatine phosphokinase evaluation verified the diagnosis of MH. The implications of delayed-onset MH and the importance of preoperative screening for potentially susceptible individuals are discussed.