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Measuring depth of anaesthesia using changes in directional connectivity: a comparison with auditory middle latency response and estimated bispectral index during propofol anaesthesia

Measuring depth of anaesthesia using changes in directional connectivity: a comparison with auditory middle latency response and estimated bispectral index during propofol anaesthesia
Measuring depth of anaesthesia using changes in directional connectivity: a comparison with auditory middle latency response and estimated bispectral index during propofol anaesthesia
General anaesthesia is associated with changes in connectivity between different regions of the brain, the assessment of which has the potential to provide a novel marker of anaesthetic effect. We propose an index that quantifies the strength and direction of information flow in electroencephalographic signals collected across the scalp, assess its performance in discriminating ‘wakefulness’ from ‘anaesthesia’, and compare it with estimated bispectral index and the auditory middle latency response. We used a step‐wise slow induction of anaesthesia in 10 patients to assess graded changes in electroencephalographic directional connectivity at propofol effect‐site concentrations of 2 μg.ml−1, 3 μg.ml−1 and 4 μg.ml−1. For each stable effect‐site concentration, connectivity was estimated from multichannel electroencephalograms using directed coherence, together with middle latency response and estimated bispectral index. We used a linear support vector machine classifier to compare the performance of the different electroencephalographic features in discriminating wakefulness from anaesthesia. We found a significant reduction in the strength of long‐range connectivity (interelectrode distance > 10 cm) (p < 0.008), and a reversal of information flow from markedly postero‐frontal to fronto‐posterior (p < 0.006) between wakefulness and a propofol effect‐site concentration of 2 μg.ml−1. This then remained relatively constant as effect‐site concentration increased, consistent with a step change in directed coherence with anaesthesia. This contrasted with the gradual change with increasing anaesthetic dose observed for estimated bispectral index and middle latency response. Directed coherence performed best in discriminating wakefulness from anaesthesia with an accuracy of 95%, indicating the potential of this new method (on its own or combined with others) for monitoring adequacy of anaesthesia.
anaesthesia, Depth, anaesthetics i.v., propofol, Monitoring, Electroencephalography
0003-2409
321-332
Lioi, Giulia
4bf7365a-17fc-46c7-b5c1-ad6deec34bc7
Bell, Steven
91de0801-d2b7-44ba-8e8e-523e672aed8a
Smith, David
217b19f1-7588-4d54-a062-8394eea6dea1
Simpson, David
53674880-f381-4cc9-8505-6a97eeac3c2a
Lioi, Giulia
4bf7365a-17fc-46c7-b5c1-ad6deec34bc7
Bell, Steven
91de0801-d2b7-44ba-8e8e-523e672aed8a
Smith, David
217b19f1-7588-4d54-a062-8394eea6dea1
Simpson, David
53674880-f381-4cc9-8505-6a97eeac3c2a

Lioi, Giulia, Bell, Steven, Smith, David and Simpson, David (2019) Measuring depth of anaesthesia using changes in directional connectivity: a comparison with auditory middle latency response and estimated bispectral index during propofol anaesthesia. Anaesthesia, 74 (3), 321-332. (doi:10.1111/anae.14535).

Record type: Article

Abstract

General anaesthesia is associated with changes in connectivity between different regions of the brain, the assessment of which has the potential to provide a novel marker of anaesthetic effect. We propose an index that quantifies the strength and direction of information flow in electroencephalographic signals collected across the scalp, assess its performance in discriminating ‘wakefulness’ from ‘anaesthesia’, and compare it with estimated bispectral index and the auditory middle latency response. We used a step‐wise slow induction of anaesthesia in 10 patients to assess graded changes in electroencephalographic directional connectivity at propofol effect‐site concentrations of 2 μg.ml−1, 3 μg.ml−1 and 4 μg.ml−1. For each stable effect‐site concentration, connectivity was estimated from multichannel electroencephalograms using directed coherence, together with middle latency response and estimated bispectral index. We used a linear support vector machine classifier to compare the performance of the different electroencephalographic features in discriminating wakefulness from anaesthesia. We found a significant reduction in the strength of long‐range connectivity (interelectrode distance > 10 cm) (p < 0.008), and a reversal of information flow from markedly postero‐frontal to fronto‐posterior (p < 0.006) between wakefulness and a propofol effect‐site concentration of 2 μg.ml−1. This then remained relatively constant as effect‐site concentration increased, consistent with a step change in directed coherence with anaesthesia. This contrasted with the gradual change with increasing anaesthetic dose observed for estimated bispectral index and middle latency response. Directed coherence performed best in discriminating wakefulness from anaesthesia with an accuracy of 95%, indicating the potential of this new method (on its own or combined with others) for monitoring adequacy of anaesthesia.

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More information

Accepted/In Press date: 14 November 2018
e-pub ahead of print date: 16 December 2018
Published date: March 2019
Keywords: anaesthesia, Depth, anaesthetics i.v., propofol, Monitoring, Electroencephalography

Identifiers

Local EPrints ID: 426958
URI: http://eprints.soton.ac.uk/id/eprint/426958
ISSN: 0003-2409
PURE UUID: df5b9d94-603e-495a-b3b3-462c63c702d1

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Date deposited: 19 Dec 2018 17:30
Last modified: 13 Nov 2021 05:22

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Contributors

Author: Giulia Lioi
Author: Steven Bell
Author: David Smith
Author: David Simpson

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