Electrolyte changes during craniotomy caused by administration of hypertonic mannitol.

We report a 31-year-old woman scheduled for a right frontal craniotomy and debulking of a recurrent grade 3 astrocytoma. Mannitol was given at the request of the surgeons. Peaked T waves were noted on electrocardiography, and electrolyte analysis showed hyperkalemia and hyponatremia.