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Please use this identifier to cite or link to this item: http://hdl.handle.net/11055/257
Title: Frontal alpha-delta EEG does not preclude volitional response during anaesthesia: prospective cohort study of the isolated forearm technique.
Authors: Gaskell, AL
Hight, D F
Winders, J
Tran, G
Defresne, A
Bonhomme, V
Raz, A
Sleigh, JW
Sanders, R D
ANZCA/FPM Author: Gaskell, AL
Sleigh, JW
Issue Date: 1-Oct-2017
Citation: British journal of anaesthesia 2017-10-01; 119(4): 664-673
Abstract: The isolated forearm test (IFT) is the gold standard test of connected consciousness (awareness of the environment) during anaesthesia. The frontal alpha-delta EEG pattern (seen in slow wave sleep) is widely held to indicate anaesthetic-induced unconsciousness. A priori we proposed that one responder with the frontal alpha-delta EEG pattern would falsify this concept. Frontal EEG was recorded in a subset of patients from three centres participating in an international multicentre study of IFT responsiveness following tracheal intubation. Raw EEG waveforms were analysed for power-frequency spectra, depth-of-anaesthesia indices, permutation entropy, slow wave activity saturation and alpha-delta amplitude-phase coupling. Volitional responses to verbal command occurred in six out of 90 patients. Three responses occurred immediately following intubation in patients (from Sites 1 and 2) exhibiting an alpha-delta dominant (delta power >20 dB, alpha power >10 dB) EEG pattern. The power-frequency spectra obtained during these responses were similar to those of non-responders (P>0.05) at those sites. A further three responses occurred in (Site 3) patients not exhibiting the classic alpha-delta EEG pattern; these responses occurred later relative to intubation, and in patients had been co-administered ketamine and less volatile anaesthetic compared with Site 1 and 2 patients. None of the derived depth-of-anaesthesia indices could robustly discrimate IFT responders and non-responders. Connected consciousness can occur in the presence of the frontal alpha-delta EEG pattern during anaesthesia. Frontal EEG parameters do not readily discriminate volitional responsiveness (a marker of connected consciousness) and unresponsiveness during anaesthesia. NCT02248623.
URI: http://hdl.handle.net/11055/257
DOI: 10.1093/bja/aex170
PubMed URL: https://www.ncbi.nlm.nih.gov/pubmed/29121278
Journal Title: British journal of anaesthesia
Type: Journal Article
Appears in Collections:Scholarly and Clinical

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