Etomidate is associated with longer seizure duration, lower stimulus intensity, and lower number of failed trials in electroconvulsive therapy compared with thiopental.

OBJECTIVE

Induction agents used for electroconvulsive therapy (ECT) may alter seizure parameters. In this study, we aimed to investigate the effects of etomidate and thiopental on seizure-related variables.

METHODS

Registries of patients who received ECT between 2010 and 2013 in a tertiary psychiatry clinic were evaluated retrospectively. The information of patients who were on the same induction agent and muscle relaxant during the whole treatment course was assessed. Primary outcome measures were total number of ECT sessions, mean peripheral and central seizure duration, cumulative stimulus intensity, and the number of adequate seizures per total number of stimuli. Secondary measures were maximum systolic-diastolic and mean blood pressure, peak heart rate, and the frequency of antihypertensive drug use during the sessions.

RESULTS

Although the total number of ECT sessions is similar between the etomidate (n = 43) and thiopenthal (n = 31) groups, the mean seizure duration per stimuli was significantly longer whereas the cumulative stimulus intensity was lower in the etomidate group. The number of adequate seizures obtained in relation with the number of stimuli was also significantly higher, indicating increased probability of eliciting an adequate seizure with etomidate. During threshold determination, the number of stimuli needed to provide an adequate seizure was marginally less with etomidate. No group difference was observed in hemodynamic changes and the frequency of antihypertensive use.

CONCLUSIONS

Etomidate use, compared with thiopental as an induction agent, is associated with longer seizure duration with less cumulative intensity. The use of etomidate reduces the number of failed trials and may prevent the application of unnecessary electrical stimuli with a possibly safe hemodynamic profile.