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Published on: January 13, 2018
Bispectral index is a topographically dependent variable in patients receiving propofol anaesthesia
P Pandin1, N Van Cutsem, T Tuna
1Department of Anesthesiology, Erasmus Hospital, Free University of Brussels Brussels, Belgium. ppandin@ulb.ac.be
British Journal of Anaesthesia
|August 25, 2006
Summary
The bispectral index (BIS) is topographically dependent, showing significant differences when measured from frontal, central, and parietal areas during propofol anesthesia. This study highlights the importance of electrode placement for accurate BIS monitoring.
Area of Science:
- Anesthesiology
- Neurophysiology
- Medical Devices
Background:
- Previous research indicated strong agreement in bispectral index (BIS) values between occipital and frontal scalp areas.
- The topographical dependency of BIS measurements across different cranial regions remained unclear.
Purpose of the Study:
- To investigate whether BIS monitoring is a topographically independent variable.
- To compare BIS values derived from central and parietal electrode placements against frontal placements.
Main Methods:
- Twenty patients (ASA I-II, 18-62 years) without neurological disorders were enrolled.
- BIS values were recorded simultaneously from frontal (F7-Cz), central (C3-Cz), and parietal (P7-Cz) montages using an Aspect A-1000 monitor.
- Data were collected during a stable propofol concentration (4-8 microg/ml) sufficient for laryngeal mask insertion.
Main Results:
- Mean BIS values at steady-state propofol concentrations differed significantly across electrode placements.
- BIS values were 32 [20-44] for frontal, 46 [28-68] for central, and 58 [41-72] for parietal leads.
- Statistical analysis (Kruskall-Wallis, Wilcoxon) confirmed significant differences (P<0.0001 and P<0.005, respectively).
Conclusions:
- The bispectral index (BIS) is a topographically dependent variable.
- Electrode placement significantly influences BIS readings during propofol anesthesia.
- These findings underscore the importance of standardized electrode positioning for reliable BIS monitoring.
