Suspected recurrence of malignant hyperthermia after post-extubation shivering in the intensive care unit, 18 h after tonsillectomy.

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