Hypokalaemia with severe rebound hyperkalaemia after therapeutic barbiturate coma

Severe disturbance of potassium balance is a rare but life-threatening complication of therapeutic barbiturate coma. A 14-yr-old patient was treated with a thiopental infusion for management of increased intracranial pressure after severe head injury. The patient had persistent hypokalaemia during the thiopental infusion. On cessation of the infusion the patient rapidly developed a tachydysrhythmia associated with a serum K+ of 7.0. Possible mechanisms of this phenomenon are discussed. We conclude that aggressive treatment of hypokalaemia during barbiturate coma should be avoided, and advocate a tapering dose of thiopental and not abrupt cessation of an infusion. Severe disturbance of plasma potassium balance is a rare but life-threatening complication of therapeutic barbiturate coma. Awareness of this complication should be raised and management altered to less aggressive treatment of hypokalaemia occurring during thiopental infusion, with a tapering dose used on discontinuation to limit a rebound phenomenon.