COMPARISON OF SPONTANEOUS FRONTAL EMG, EEG POWER SPECTRUM AND BISPECTRAL INDEX TO MONITOR PROPOFOL DRUG EFFECT AND EMERGENCE

Background: The aim of this study was to investigate the accuracy of f rontal spontaneous electromyography (SEMG) and EEG spectral edge frequ ency (SEF 95%), median frequency (MF), relative delta power (RDELTA) a nd bispectral index (BIS) in monitoring loss of and return of consciou sness and hypnotic drug effect during propofol administration at diffe rent calculated plasma target concentrations. Methods: Propofol was ad ministered by using a target-controlled infusion at different propofol steady-state concentrations. All variables were measured simultaneous ly at specific calculated concentrations and endpoints. Results: Loss of consciousness was accurately monitored by BIS, SEMG and SEF 95%, an d propofol drug effect by BIS only Return of consciousness was predict ed by BIS, MF and SEF 95%. Due to the biphasic EEG pattern of propofol and the lack of reproducible data at specific propofol concentrations , the clinical usefulness of SEF 95%, MF and RDELTA was very Limited. SEMG was useful to detect loss and return of consciousness, but withou t predictive value. Conclusions: The BIS might be an accurate measure to monitor depth of anaesthesia and hypnotic drug effect. Other neurop hysiologic measures have limited value to monitor depth of anaesthesia and hypnotic drug effect. (C) Acta Anaesthesiologica Scandinavica 42 (1998).