Electroencephalographic Variation during End Maintenance and Emergence from Surgical Anesthesia

• Type of Material: Article
• Authors: Divya Chander, Stanford University; Paul Garcia, Emory University; Jono N. MacColl, University of Auckland; Sam Illing, University of Auckland; Jamie W. Sleigh, University of Auckland
• Language: English
• Date: 2014-09-29
• Publisher: Public Library of Science
• Publication Version: Final Published Version
• Copyright Statement: This is an open-access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose.
• License: Creative Commons Creative Commons CC0 1.0 Universal
• Final Published Version (URL): http://dx.doi.org/10.1371/journal.pone.0106291
• Title of Journal or Parent Work: PLoS ONE
• ISSN: 1932-6203
• Volume: 9
• Issue: 9
• Start Page: e106291
• End Page: e106291
• Grant/Funding Information: This work was supported by a collaborative grant from the James S. McDonnell Foundation, and departmental resources of the authors.
• Keywords: Consciousness; Science & Technology; GABA(A) RECEPTORS; Anesthetics; Multidisciplinary Sciences; Evolutionary emergence; THALAMOCORTICAL NEURONS; Electroencephalography; RIGHTING REFLEX; CONTROLLED INFUSION; General anesthesia; SPINDLE OSCILLATIONS; PROPOFOL ANESTHESIA; Sleep; SLEEP-DEPRIVATION; ISOFLURANE GENERAL-ANESTHESIA; MEMORY CONSOLIDATION; Science & Technology - Other Topics; Anesthesia; Electromyography; BISPECTRAL INDEX
• Research Categories: Health Sciences, Medicine and Surgery; Health Sciences, General

Abstract

The re-establishment of conscious awareness after discontinuing general anesthesia has often been assumed to be the inverse of loss of consciousness. This is despite the obvious asymmetry in the initiation and termination of natural sleep. In order to characterize the restoration of consciousness after surgery, we recorded frontal electroencephalograph (EEG) from 100 patients in the operating room during maintenance and emergence from general anesthesia. We have defined, for the first time, 4 steady-state patterns of anesthetic maintenance based on the relative EEG power in the slow-wave (,14 Hz) frequency bands that dominate sleep and anesthesia. Unlike single-drug experiments performed in healthy volunteers, we found that surgical patients exhibited greater electroencephalographic heterogeneity while re-establishing conscious awareness after drug discontinuation. Moreover, these emergence patterns could be broadly grouped according to the duration and rapidity of transitions amongst these slow-wave dominated brain states that precede awakening. Most patients progressed gradually from a pattern characterized by strong peaks of delta (0.5-4 Hz) and alpha/spindle (8-14 Hz) power ('Slow-Wave Anesthesia') to a state marked by low delta-spindle power ('Non Slow-Wave Anesthesia') before awakening. However, 31% of patients transitioned abruptly from Slow-Wave Anesthesia to waking; they were also more likely to express pain in the post-operative period. Our results, based on sleep-staging classification, provide the first systematized nomenclature for tracking brain states under general anesthesia from maintenance to emergence, and suggest that these transitions may correlate with post-operative outcomes such as pain.