Frontal electroencephalogram reveals emergence-like brain activity occurring during transition periods in cardiac surgery

Abstract

Background: Cardiac surgery has one of the highest incidences of intraoperative awareness. The periods of initiation and discontinuation of cardiopulmonary bypass could be high-risk periods. Certain frontal EEG patterns might plausibly occur with unintended intraoperative awareness. This study sought to quantify the incidence of these pre-specified patterns during cardiac surgery. Methods: Two-channel bihemispheric frontal EEG was recorded in 1072 patients undergoing cardiac surgery as part of a prospective observational study. Spectrograms were created, and mean theta (4e7 Hz) power and peak alpha (7e17 Hz) frequency were measured in patients under general anaesthesia with isoflurane. Emergence-like EEG activity in the spectrogram during surgery was classified as an alpha peak frequency increase by 2 Hz or more, and a theta power decrease by 5 dB or more in comparison with the median pre-bypass values. Results: Data from 1002 patients were available for analysis. Fifty-five of those patients (5.5%) showed emergence-like EEG activity at least once during surgery with a median duration of 13.2 min. These patients were younger (median age, 59 vs 67 yr; P<0.001) and the median end-tidal isoflurane concentration before cardiopulmonary bypass was higher (0.82 vs 0.75 minimum alveolar concentration [MAC]; P¼0.013). There was no significant difference between those with or without emergence-like EEG activity in sex, lowest core temperature, or duration of surgery. Forty-six of these EEG changes (84%) occurred within a 1 h time window centred on separation from cardiopulmonary bypass. Conclusion:The findings of this study suggest that approximately one in 20 patients undergoing cardiac surgery with a volatile anaesthetic agent have a sustained EEG pattern while surgery is ongoing that is often seen with emergence from general anaesthesia. Monitoring the frontal EEG during cardiopulmonary bypass may identify these events and potentially reduce the incidence of unintended awareness. Clinical trial registration: NCT 02976584.

A Narrative Review Illustrating the Clinical Utility of Electroencephalogram-Guided Anesthesia Care in Children

“…[119][120][121] Frontal EEG monitoring in patients undergoing CPB revealed a high incidence of emergence-like brain activity occurring during surgery, typically during transition periods within an hour of separating from CPB. 122 EEG monitoring may identify these events and potentially reduce the incidence of light anesthesia or awareness. 123,124 At the onset of cooling, periodic complexes appear on the background of continuous EEG activity and were often asynchronous.…”

Age, minimum alveolar concentration and choice of depth of sedation monitor: examining the paradox of age when using the Narcotrend monitor

“…21,22 Ultimately, it may be perhaps most beneficial to look at the raw EEG or spectrogram to better guide anaesthetic titration. 12,13,16,39 There are also good reasons to question the accuracy of the BIS with increasing age, based on known EEG changes with age, and primarily the increased relative power in high frequency ranges, as has been well noted before. 18,25,33,40 This increased power in the higher frequency ranges may be because of a decreasing broadband 1/f spectral effect, which is also reflected in entropic measures (increased entropy).…”

“…Until companies publish their algorithms, scientists and clinicians alike are left in the dark as to which EEG signal changes lead to which index changes, and thus to the accuracy of these vital clinical indicators 21,22 . Ultimately, it may be perhaps most beneficial to look at the raw EEG or spectrogram to better guide anaesthetic titration 12,13,16,39 …”

Raspberry Pi-Based Data Archival System for Electroencephalogram Signals From the SedLine Root Device

“…Multiple research groups have created EEG signal databases during anesthesia. Kaiser et al 14 recorded 2-channel bihemispheric frontal EEG in 1072 patients undergoing cardiac surgery from a Narcotrend DoA-monitor (MonitorTechnik). Hesse et al 15,16 enrolled and collected EEG from 626 unique subjects to study the association of EEG trajectories during anesthesia emergence with postanesthesia care unit (PACU) delirium.…”