The comparative effects of methohexital, propofol, and etomidate for electroconvulsive therapy

The intravenous anesthetics which are commonly used for electroconvulsive therapy (ECT) possess dose-dependent anticonvulsant properties. Since the clinical efficacy of ECT depends on the induction of a seizure of adequate duration, it is important to determine the optimal dose of the hypnotic for use during ECT. We compared the duration of seizure activity and cognitive recovery profiles after different doses of methohexital, propofol, and etomidate administered to induce hypnosis prior to ECT. Ten outpatients with major depressive disorders receiving maintenance ECT participated in this prospective, randomized, cross-over study. Patients were premedicated with glycopyrrolate, 0.2 mg intravenously (IV), and labetalol, 20-30 mg IV, and hypnosis was induced with 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 10-15 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 bilateral electrical stimulus, the duration of the resulting electroencephalographic (EEG) and motor seizures were recorded. A total of 90 ECT treatments were evaluated. The durations of EEG and motor seizures were longest after etomidate and shortest after propofol. There were no significant dose-related differences in motor and EEG seizure durations (means ± SD) after 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 and EEG seizure durations (i.e., 37 ± 10 and 58 ± 12, 36 ± 8 and 62 ± 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 propofol, respectively). The awakening times were similar, regardless of the hypnotic or dose administered. The rate of cognitive recovery was prolonged after ECT treatments with a longer duration of seizure activity. Discharge time was 5-7 min longer after etomidate than methohexital or propofol. Etomidate, 0.15-0.3 mg/kg, has minimal effect on the duration 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 mg/kg, lead to 35%-45% decreases in ECT-induced seizure duration compared to etomidate. We conclude that etomidate may be a useful alternative to propofol and methohexital for ECT therapy.