Case of hyperkalemia after the administration of hypertonic mannitol during craniotomy

We report a case of severe hyperkalemia which developed following administration of mannitol during craniotomy. The blood potassium levels rose from 4.8 mEq x l(-1) to 6.7 mEq x l(-1) 30 minutes after the infusion of mannitol 300 ml during the operation for brain tumor. Since the patient did not develop metabolic acidosis, the hyperkalemia was probably caused by a rise in plasma osmotic pressure resulting from mannitol infusion. The risk factors for hyperkalemia have not yet been determined, and it is necessary to monitor carefully the electrocardiogram and electrolyte levels during the infusion of mannitol.