TOPOGRAPHIC ELECTROENCEPHALOGRAM OF PROPOFOL-INDUCED CONSCIOUS SEDATION

Objectives: To determine the effects of increasing doses of propofol t hat induce conscious sedation on the topographic electroencephalogram (EEG) of human volunteers and to test the hypothesis that more frontal brain areas are affected by low doses of propofol. Methods: The scalp EEG was recorded monopolarly from 16 different sites based on the 10- 20 International System, Microcomputer-based hardware and RHYTHM 7.1 s oftware were used to obtain quantitative power frequency topographic E EG data. A total of 10 normal adult volunteers were given incremental doses of propofol targeted to plasma concentrations of 0 to 1200 ng/ml . Results: Sedative concentrations of propofol produced a dramatic inc rease in beta(1), an increase in alpha, and beta(2), and an increase i n delta activity at the largest concentration, with almost no change i n theta activity. The increase in beta(1) activity had a linear correl ation with plasma propofol levels (r = 0.9). Topographic mapping indic ated that beta, activation was primarily in the frontal and central re gions, with focal changes more in the left hemisphere. Conclusions: To pographic brain EEG mapping techniques indicate that frontal brain bet a(1) EEG activity may be useful as an objective brain index of propofo l conscious sedation.