Comparison of electrical measurements on constant voltage and constant current ECT machines.

Electrical measurements were made during treatment of two groups of patients, one group receiving treatment from a constant current ECT machine and the other from a constant voltage machine. The electrical impedance and energy were calculated and compared for the two groups. More energy was delivered by the constant voltage than by the constant current machine, but the spread of energy delivered was comparable. With a consistent technique for applying the electrodes there is little to choose between these machines, but the constant current machine may be preferred where consistency cannot be achieved.