THE COMPARATIVE EFFECTS OF METHOHEXITAL, PROPOFOL, AND ETOMIDATE FOR ELECTROCONVULSIVE-THERAPY

The intravenous anesthetics which are commonly used for electroconvuls ive therapy (ECT) possess dose-dependent anticonvulsant properties. Si nce the clinical efficacy of ECT depends on the induction of a seizure of adequate duration, it is important to determine the optimal dose o f the hypnotic for use during ECT. We compared the duration of seizure activity and cognitive recovery profiles after different doses of met hohexital, propofol, and etomidate administered to induce hypnosis pri or to ECT. Ten outpatients with major depressive disorders receiving m aintenance ECT participated in this prospective, randomized, cross-ove r study. Patients were premedicated with glycopyrrolate, 0.2 mg intrav enously (IV), and labetalol, 20-30 mg IV, and hypnosis was induced wit h an IV bolus injection of methohexital or propofol (0.75, 1.0, and 1. 5 mg/kg), or etomidate (0.15, 0.2, and 0.3 mg/kg), administered over 1 0-15 s. Adequate muscle paralysis was achieved with succinylcholine, 1 .0-1.4 mg/kg IV. Each patient's seizure threshold was determined prior to enrollment in the study and the electrical stimulus variables were kept constant throughout the study period. After delivery of a bilate ral electrical stimulus, the duration of the resulting electroencephal ographic (EEG) and motor seizures were recorded. A total of 90 ECT tre atments were evaluated. The durations of EEG and motor seizures were l ongest after etomidate and shortest after propofol. There were no sign ificant dose-related differences in motor and EEG seizure durations (m eans +/- SD) af ter the low, intermediate, and high doses of etomidate of 44 +/- 11 and 77 +/- 19, 43 +/- 10 and 76 +/- 34, 42 +/- 16 and 78 +/- 56 s, respectively. Conversely, both methohexital and propofol, 0 .75, 1.0, and 1.5 mg/kg, produced dose-dependent decreases in motor an d EEG seizure durations (i.e., 37 +/- 10 and 58 +/- 12, 36 +/- 8 and 6 2 +/- 24, and 29 +/- 13 and 48 +/- 20 for methohexital; 34 +/- 15 and 56 +/- 29, 31 +/- 8 and 50 +/- 17, and 20 +/- 6 and 33 +/- 12 for prop ofol, respectively). The awakening times were similar, regardless of t he hypnotic or dose administered. The rate of cognitive recovery was p rolonged after ECT treatments with a longer duration of seizure activi ty. Discharge time was 5-7 min longer after etomidate than methohexita l or propofol. Etomidate, 0.15-0.3 mg/kg, has minimal effect on the du ration of ECT-induced seizure activity. However, recovery of cognitive functions was prolonged after etomidate because of the longer period of seizure activity. Propofol and methohexital, at doses more than 1 m g/kg, lead to 35%-45% decreases in ECT-induced seizure duration compar ed to etomidate. We conclude that etomidate may be a useful alternativ e to propofol and methohexital for ECT therapy.