Successful treatment of an episode of malignant hyperthermia using a large dose of dantrolene

This clinical case report describes the use of extremely high doses of dantrolene in the management of an episode of malignant hyperthermia (MH). A 6-year-old, 25 kg girl underwent anesthetic induction with halothane for an elective inguinal herniorrhaphy. Tachydysrhythmias, laryngospasm, opisthotonos, rhabdomyolysis, and profound metabolic acidosis ensued as features of an MH crisis. Initial dantrolene administration did not alleviate the symptoms. Increasing doses of dantrolene eventually totaling 42 mglkg, along with symptomatic supportive care, were administered successfully to treat the event. It is postulated that the severe muscle rigidity may have precluded the circulation of dantrolene to its site of action. The role of the Malignant Hyperthermia Association of the United States (MHAUS) Hotline as a 24-hour consultative service is noted.