Neuromonitoring-guided anesthesia depth versus four-minute anesthesia-to-stimulation time interval in electroconvulsive therapy for depressive disorders - A single-blinded, prospective, randomized and controlled study

Background: Anesthesia depth influences seizure quality in patients undergoing electroconvulsive therapy (ECT). EEG-based neuromonitoring has been shown to detect adequate anesthesia depth for ECT. Anesthesia depth-guided ECT management may therefore be a reliable alternative to the predetermined anesthesia-to-stimulation time interval.

Methods: Patients with depressive disorders and a Montgomery-Asberg Depression Rating Score ≥ 18 were randomly assigned. The anesthesia depth-guided group received stimulation between Narcotrend™ index ratings of 41 and 64 and was compared to the control group with a predetermined anesthesia-to-stimulation time interval of four minutes. The primary endpoint was seizure quality.

Results: A total of 225 interventions were conducted in 30 patients. Significant differences were observed between the two groups regarding stimulation intervals (225.0 ± 34.2 s vs. 240.0 ± 0 s; p < 0.001) and the index before electric stimulation (45.0 ± 15.7 vs. 35.0 ± 13.0; p < 0.001). No significant differences in overall seizure quality were found between the groups. The midictal amplitude was higher in the anesthesia depth-guided group (209.2 ± 92.6 vs. 152.6 ± 80.0; p = 0.009). Because of inadequate anesthesia depth, 54 interventions were discontinued for safety reasons.

Limitations: The number of per protocol completed interventions is small due to high exclusion rate from protocol violations.

Conclusions: Anesthesia depth-guided ECT management did not significantly improve overall seizure quality compared to a four-minute anesthesia-to-stimulation time interval.

Keywords: ASTI, anesthesia-to-stimulation time interval; Electroconvulsive therapy; Electroencephalographic monitoring; Major depressive disorder; Seizure quality.