Suspected recurrence of malignant hyperthermia after postextubation shivering in the intensive care unit, 18 h after tonsillectomy

A 25-yr-old man, subsequently shown to be malignant hyperthermia (MH) susce ptible by in vitro contracture testing, developed MH during anaesthesis for tonsillectomy. Prompt treatment, including dantrolene, led to rapid resolu tion of the metabolic crisis. Eighteen hours later the patient's trachea wa s extubated in the ICU, when he had been stable and apyrexial overnight. Tw enty minutes after extubation, an episode of shivering was followed by the onset of tachycardia, hypertension, tachypnoea and a rapid increase in temp erature. Recurrence of MH was suspected and the patient was given another d ose of dantrolene with good clinical effect. Shivering in this patient may have been an indicator or a causative factor of recurrence of MH.