The effect of modified electroconvulsive therapy on plasama potassium concentration.

The influence of modified Type 11 electroconvulsive therapy (ECT) on plasma potasium was studied in 60 patients anaesthetized with a barbiturate and suxamethonium and the finding compared with a "control" group of patients having the same anaesthesia but not ECT. In the ECT series, plasma potassium concentration increased to a maximun 1 min after suxamethonium fasciculations and this increase occurred earlier and was more marked than that observed in the control group. It was also slightly shorter in duration, as was the comparable period of respiratory depression. These findings can be accounted for by the synchronous contraction of muscles containing blood with an increased potassium concentration following suxamethonium.