Seizure quality in bilateral electroconvulsive therapy: the influence of hyperventilation, electrode placement, and anesthesia

Abstract Electroconvulsive therapy (ECT) is an effective psychiatric treatment and relies on an iatrogenically induced, generalized seizure. Seizure quality scores have been developed to predict treatment outcomes of ECT. Its intensity can be governed by various parameters like electrode placement, anesthesia, and the systemic levels of CO₂. The aim of this retrospective study was to investigate whether reducing end-tidal CO₂ (etCO₂) through hyperventilation prior to ECT seizure would improve seizure quality score considering electrode placement and anesthetic agent. Case notes from 2023 were reviewed and seizure quality scores, pre-seizure etCO₂, electrode placement, and anesthetic agent were obtained. The resulting 732 ECTs from 68 patients were analyzed. Lower etCO₂ and its interaction with main anesthetic agent and different bilateral electrode placement were not significantly associated with improved seizure quality overall. Higher age was associated with a decrease in seizure quality (β = -0.03, SE = 0.01, z = − 5.58, p < .001). Post-hoc power analysis indicated sample sizes of at least 400 patients to detect isolated etCO 2 effects. Seizure quality should be understood as a complex interplay of technical, neurophysiological, and patient-related factors. Large and standardized multicenter studies are needed to explore the influence of treatment protocols on seizure quality.