Total Energy and Rate of Application as Measures of the Electroconvulsive Therapy Stimulus

This study evaluated the utility of two measures of the electroconvulsive therapy (ECT) stimulus: Total energy and rate of application of energy. Data for more than 2,000 trials drawn from six previous studies were divided into success and failure groups based on the production of a satisfactory clinical convulsion. The distributions and descriptive statistics for both measures and all studies were presented. The range for energy was 4-80+ J, with both successes and failures proportionately distributed across the entire range. Rate varied from 1 to 16+ J/s, also with proportional distribution. The presence of a different interpulse interval in some of the studies allowed a demonstration showing that the rate measure was susceptible to considerable influence by this stimulus characteristic. As clinical considerations reduce the number of observations made at the higher energy levels, it was concluded that the influence of both energy and rate of application was underestimated substantially. Both energy and rate supply useful information about the ECT stimulus, but are much too limited to serve as adequate descriptors. Clinical illustrations are provided.