Sedative doses of propofol increase beta activity of the processed electroencephalogram

The effects of sedative infusions of propofol on the processed electroencephalograms (EEG) of eight healthy male volunteers were studied. EEG data for aperiodic analysis were collected during three 5-min periods: before propofol, during propofol infusion, and 30 min after termination of the infusion. After an initial dose of 1 mg/kg, subjects received a propofol infusion titrated to produce a standard level of conscious sedation. The infusion rate was 84 +/- 27 micrograms.kg-1 x min-1 (mean +/- SE) and plasma propofol levels were 2180 +/- 43 ng/mL. Total EEG power, defined as the sum of the squares of peak-to-peak amplitudes during each 5-s epoch, increased from 1350 +/- 295 microV2 x epoch-1 to 9675 +/- 2390 microV2 x epoch-1 during the propofol infusion (P < 0.05); it returned to 1445 +/- 145 microV2 x epoch-1 30 min after the infusion was discontinued (P < 0.05 vs the result during propofol). The change in total power was accompanied by a change in the distribution of power within the EEG spectrum, as the fraction of activity in the beta-band (12-35 Hz) increased during the infusion from 23% +/- 3% to 44% +/- 5% (P < 0.05). Thirty minutes after the infusion was terminated, the distribution of activity within the EEG spectrum had reverted to pre-propofol patterns. The similarity of EEG effects seen with sedative doses of propofol and benzodiazepines suggests that these drugs may share some neurochemical effects.