EEG Acquisition and Analysis of Anesthesia Recovery

Electroencephalographic data was acquired using a BIS Monitor (BIS VISTA Monitoring System, Aspect Medical Systems, Newton, MA, USA) with a BIS Quatro sensor (Medtronic, Dublin, Ireland) on the left forehead. The raw data consisted of two channels of data (sampling rate, 128 Hz) with a reference channel on the left forehead, and it was exported from the BIS Monitor and imported for analysis via MATLAB (version R2020b), where analysis was performed on the first channel. Raw EEG amplitude was converted into microvolts using a coefficient of 0.05 (Connor, 2022 (link)). Each participant underwent a 5-min resting baseline recording, and data was acquired from pre-bolus until spontaneous waking during recovery. EEG data was acquired for a total of 114 infusions across 21 subjects. To characterize variation across scalp locations, 9 participants also had one recording of 64-channel EEG (sampling rate, 500 Hz) using an actiCHamp amplifier and an actiCAP slim electrode system (BrainVision, Garner, NC, USA).