Comparison of propofol and etomidate regarding impact on seizure threshold during electroconvulsive therapy in patients with schizophrenia.

Background: While propofol is known to shorten seizures during electroconvulsive therapy, in our previous study on patients with schizophrenia, there was no need for more frequent restimulations when using propofol compared with etomidate. We hypothesized that etomidate and propofol have similar effects on seizure activity in cases where seizure duration is shorter than 20 seconds. In this study, etomidate and propofol are compared regarding their impact on seizure threshold and seizure duration.

Method: 30 schizophrenic patients participated in this prospective randomized cross-over study. For anesthetic induction were 1 mg/kg of propofol or 0.2 mg/kg of etomidate used alternately. For both anesthetics, seizure threshold was determined by titrating the dose of the stimulus necessary for eliciting a seizure. Seizure durations were also compared.

Results: After etomidate induction, seizure durations registered either by EEG or by EMG were longer than propofol treated cases (EEG: 49.6+/-23.1 s, versus 39.7+/-19 s, p=0.026; EMG: 41.4+/-22 s, versus 32.8+/-17.6 s, p=0.016). However, no significant differences were found for minimum seizure eliciting stimulation energy or the number of restimulations between the two anesthetics (41.58 mC+/-13.6 mC, versus 41.58 mC+/-11.1 mC, p=1.00).

Conclusion: During the ECT of patients with schizophrenia, propofol was shown to possess significant seizure-shortening properties, but it does not elevate seizure threshold or drop seizure duration under the minimal threshold more frequently than etomidate does. Based on these findings, we conclude that the use of propofol does not result in a greater electric load on the patients than etomidate.