Diversity of functional connectivity patterns is reduced in propofol‐induced unconsciousness

Abstract

This study suggests that a scarcity of functional configurations is closely associated with anesthetically induced unconsciousness, and shows promise as a basis for a new consciousness monitoring system during general anesthesia. Hum Brain Mapp 38:4980-4995, 2017. © 2017 Wiley Periodicals, Inc.

Phase lag entropy as a hypnotic depth indicator during propofol sedation

“…These data are supported by later studies of anterior–posterior phase synchronisation and disruption of frontal–parietal communication by various anaesthetics . Temporal behaviours of the phase relationship between prefrontal and frontal regions have demonstrated very similar results to those seen in the phase relationship between frontal and parietal regions . The dynamics of the phase relationship between frontal region channels become progressively less diverse and more stereotyped during unconsciousness, quantified as a reduction in PLE .…”

“…We have demonstrated that PLE has potential as a hypnotic depth indicator. The new measure, PLE, calculates the diversity of the temporal patterns of the phase relationship of the electro‐encephalographic signals obtained from two channels at the prefrontal and frontal regions of the brain . Consciousness is characterised by a balance between feedforward and feedback connectivity measured using the transfer entropy technique .…”

“…Therefore, to identify levels of consciousness, it is essential to consider the phase information of the electro‐encephalogram on the frontal region. The Bispectral Index TM (BIS, Covidien, Boulder, CO, USA), most widely used for monitoring consciousness, based on the power spectral and the bispectral analyses of a single channel electro‐encephalography signal , cannot provide adequate information about functional connectivity in the brain . Studies have demonstrated poor correlation between the BIS and the Sedation‐Agitation Scale .…”

“…A new measure has been developed called phase lag entropy (PLE, PLEM™ monitor, Inbody, Seoul, Korea) that calculates the diversity of the temporal patterns of the phase relationship. The PLE reflects whether interactions between the pairs of electro‐encephalography signals from two channels consist of diverse or stereotypic patterns . Our aim was to evaluate the performance of the PLE as a hypnotic depth index, in comparison with BIS, during sedation with target‐controlled infusion of propofol.…”

Monitoring of anesthetic depth and EEG band power using phase lag entropy during propofol anesthesia

“…Generally, loss of consciousness (LOC) is marked by an increase in low-frequency (< 1 Hz) EEG power, the loss of spatially coherent occipital alpha (8)(9)(10)(11)(12) Hz) oscillations, and the appearance of spatially coherent frontal alpha oscillations [7]; these dynamics are then reversed during recovery of consciousness (ROC) [8]. There have been reports of changes in functional connectivity and disruptions of frontal EEG communication in the brain during anesthesia with propofol [4,9,10], sevoflurane [10][11][12], and ketamine [10].…”