Comparison of Electroconvulsive Therapy Seizure Outcomes When Using Methohexital Versus Propofol

OBJECTIVES: To compare seizure parameters and treatment burden between methohexital and propofol during routine electroconvulsive therapy (ECT), focusing on seizure duration, treatment efficiency, and missed seizures. METHODS: This retrospective chart review examined differences in seizure outcomes between 2 commonly used agents, methohexital and propofol, at the Parkwood Institute from October 2017 to October 2019. RESULTS: A total of 132 adult patients were included: 47 received methohexital (mean age 60.9±15.4; 44.7% male) and 85 received propofol (mean age 55.1±17.1; 35.3% male). No significant demographic differences were observed. Methohexital was associated with longer motor (35.6±19.7 vs. 23.4±11.7 s; P<0.001) and EEG (50.8±28 vs. 36.8±19.2 s; P=0.003) seizure durations. It was also directly associated with a higher number of total ECT treatments (13±6.5 vs. 11±5.3; β=0.29, P<0.001), though the raw difference was only marginally significant (P=0.08). Missed seizures were slightly fewer with methohexital (1.9±2.9 vs. 2.4±2.1; P=0.251). Multilevel structural equation modelling revealed a statistically significant indirect pathway through which methohexital influenced treatment continuity (Estimate = -0.743, P=0.044, standardized β=-0.061), mediated through motor seizure slope and missed seizures. CONCLUSIONS: While methohexital may initially enhance seizure quality, its decline in efficacy over time may compromise treatment efficiency. These findings suggest methohexital's initial seizure advantages may be offset by declining seizure duration across treatments and its downstream association with missed seizures. These findings may inform more efficient ECT anesthetic choices.