Bispectral Index Monitoring and Seizure Quality Optimization in Electroconvulsive Therapy

Introduction: In ECT, the relative timing of seizure induction and anesthesia may critically impact on seizure quality when anesthetic agents with anticonvulsive properties such as barbiturates or propofol are used. Measuring the depth of anesthesia by bispectral index (BIS) monitoring and thereby identifying the optimal moment for seizure induction might enhance seizure quality. Methods: Seizures from 869 individual ECT sessions with thiopental anesthetic from 118 patients were examined in this retrospective study. The associations of the BIS value at the moment of seizure induction with 7 established seizure parameters and with a novel model of seizure quality were tested by regression analyses. Results: BIS value at induction correlated positively with seizure duration, central inhibition, coherence and maximal heart rate, but not with midictal amplitude. Higher seizure quality was related with a higher BIS value at the moment of seizure induction. Discussion: The BIS value at seizure induction serves as an independent predictor of seizure quality, influencing most other established markers. BIS monitoring appears as a simple tool to identify the optimal moment for seizure induction.