Effects of sustained Trendelenburg position on the spectral signatures of the EEG: implications for the consistency of the level of anesthesia, an observational study
Authors' conclusion
BIS Index and SEF95 remained consistent during prolonged Trendelenburg positioning. The reduction in EEG singal power across 0-45 Hz caused a vertical shift in the power spectrum with minimal changes in its spectral profile.
Study context
- Population
- Patients undergoing robot-assisted radical prostatectomy in steep Trendelenburg positionanalysed
- Participants
- 18 patients
- Outcome
- Change from baseline and trend over time of BIS Vista monitor (BIS Index, SEF95, EEG-BIS) and 4-electrode EEG (EEG-BrVis) parameters
- Follow-up
- Baseline, 30 min after Trendelenburg positioning, then every 60 min until procedure completion
Methodological detailsMean surgical duration 269 ± 69 min; Trendelenburg angles 32º to 41º
- Mean surgical duration 269 ± 69 min; Trendelenburg angles 32º to 41º
Main finding
As reported in the abstract
BIS Index, SEF95 and EEG power over time
- Mean change in BIS Index, left hemisphere
- 0.017 ± 0.01 (p = 0.096)
- Mean change in BIS Index, right hemisphere
- 0.016 ± 0.011 (p = 0.162)
- SEF95 change, left hemisphere
- - 0.002 ± 0.002 Hz (p = 0.390)
- SEF95 change, right hemisphere
- - 0.002 ± 0.002 Hz (p = 0.326)
- Significant decrease over time in AUC of power spectrum, both EEG
- p < 0.001
- Significant decrease over time in all frequency bands power, both EEG
- p < 0.001
Observational data: associations, not effects.
Original publication
Effects of sustained Trendelenburg position on the spectral signatures of the EEG: implications for the consistency of the level of anesthesia, an observational study. J Clin Monit Comput. Published 22 December 2025. doi:10.
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