The optimum induction agent for anesthesia for electroconvulsive therapy (ECT) has been long debated. Ideal agent should be short acting with minimal suppression of seizure potentials. Recent studies have suggested longer seizure duration with etomidate in comparison to propofol, thiopental, and methohexital. The aim of the present meta-analysis was to pool data available from studies comparing systematically the efficacy of etomidate against other induction agents in terms of seizure duration (both electroencephalography (EEG) and motor).
We searched the PubMed, Embase, and Cochrane registry for trials evaluating etomidate against methohexital, propofol, or thiopental for duration of EEG or motor seizure in patients undergoing ECT. Specific adverse effects reported were also identified.
Seventeen trials were identified involving 704, 84, 2491, and 258 setting of ECT using etomidate, methohexital, thiopental, and propofol, respectively. In the etomidate group, pooled EEG seizure duration was longer by 2.23 seconds (95% confidence interval [CI], −3.62 to 8.01; P = 0.456) than methohexital, longer by 17.65 seconds (95% CI, 9.72–25.57; P < 0.001) than propofol, and longer by 11.81 seconds (95% CI, 4.26–19.35; P = 0.003) than thiopental. Pooled motor seizure duration was longer in etomidate group by 1.45 seconds (95% CI, −4.79 to 7.69; P = 0.649) than methohexital, longer by 11.13 seconds (95% CI, 6.64–15.62; P < 0.001) than propofol, and longer by 3.60 seconds (95% CI, 2.15–5.06; P < 0.001) than thiopental. Myoclonus (6 trials) and painful injection (4 trials) were commonest adverse effects with etomidate.
Etomidate is clearly better in terms of seizure duration potential (both motor and EEG) than propofol and thiopental. Superiority/inferiority over methohexital could not be demonstrated with the presently available literature.