The effectiveness of BIS monitoring during electro-convulsive therapy: A systematic review and meta-analysis

Study objective: Electroconvulsive therapy (ECT) has been shown to be highly effective in patients suffering from treatment-resistant depression. ECT procedure is performed under general anesthesia but the impact of anesthesia depth on seizure characteristics and clinical outcome remains unclear. We aimed to study the effects of BIS monitoring on electric and clinical response to ECT treatment. Design: Meta-analysis searching PubMed, Web of Science, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, EMBASE, PsycINFO database, and Google Scholar. Patients/interventions: Studies comparing different BIS levels during ECT. Measurement: The primary outcome measured the electrical seizure duration. Secondary outcomes measured the clinical seizure duration, and correlation between pre-ictal BIS level and awakening time. Difference in means (MD) was used for effect size. Main results: Among 38 eligible studies, 7 were analyzed including 260 patients, aged from 16 to 80 years old, benefiting from 1283 ECT sessions. Higher BIS levels were associated with longer electric seizures duration (correlation 0.61, 95% CI [0.39-0.75], 7 studies) and longer motor seizures duration (correlation 0.72, 95% CI [0.29-0.91], 6 studies). Conclusions: High values of pre-ictal BIS are associated with improved seizure duration. The usefulness of systematic BIS monitoring during all ECT procedures should be further studied to better identify adequate BIS levels according to patient's characteristics.