Changes in plasma potassium concentration after depolarizing blockers in anaesthetized man.

Changes in plasma potassium concentration after administration of depolarizing neuromuscular blockers were measured in patients during halothane-nitrous oxide anaesthesia. Suxamethonium 100 mg intravenously caused a peak rise of 0.55 m.equiv/1. and decamethonium 4 mg produced an elevation of similar magnitude. Injured patients had increases in potassium averaging 1.80 m.equiv/1. there being a direct correlation between degree of rise and time since injury. By giving tubocurarine 0.1 mg/kg body weight 5 minutes beforehand, the elevation in potassium caused by suxamethonium, though not by decamethonium, could be halved.