Immediate changes in plasma potassium, sodium and chloride concentrations induced by suxamethonium.

Four groups of healthy female patients were anaesthetized with wither thiopentone, Althesin or nitrous oxide-oxygen with and without halothane. The concentrations of the plasma electrolytes were measured before and at varying times up to 10 min after the administration of suxamethonium 1 mg/kg. Asmall, but significant, biphasic increase in plasma potassium concentration was found when suxamethonium was administered to patients in whom anaesthesia was induced with thiopentone, Althesin and nitrous oxide-oxygen. The initial increase in plasma potassium concentration was greater in the Althesin group thanin the other two groups. A more delayed, but sustained, increase in plasma potassium concentration was found following induction with nitrous oxide-oxygen-halothane. There were no significant changes in the plasma concentrations of sodium or chloride exceptin the halothane-nitrous oxide-oxygen series.