Korean J Anesthesiol.  2019 Aug;72(4):351-356. 10.4097/kja.d.19.00019.

Assessment of phase-lag entropy, a new measure of electroencephalographic signals, for propofol-induced sedation

• Jun MR
• Yoo JH
• Park SY
• Na S
• Kwon H
• Nho JH
• Kim SI

• KMID: 2458320
• DOI: http://doi.org/10.4097/kja.d.19.00019

Abstract

BACKGROUND
Phase-lag entropy (PLE) was recently described as a measurement of temporal pattern diversity in the phase relationship between two electroencephalographic signals from prefrontal and frontal montages. This study was performed to evaluate the performance of PLE for assessing the depth of sedation.
METHODS
Thirty adult patients undergoing upper limb surgery with a brachial plexus block were administered propofol by target-controlled infusion. The depth of sedation was assessed using the Observer's Assessment of Alertness/Sedation (OAA/S) scale. The effect-site concentration (Ce) of propofol was initially started at 0.5 μg/ml and was increased in increments of 0.2 μg/ml until an OAA/S score of 1 was reached. Three minutes after the target Ce was reached, the PLE, bispectral index (BIS), and level of sedation were assessed. Correlations between the OAA/S score and PLE or BIS were determined. The prediction probabilities (P(k)) of PLE and BIS were also analyzed.
RESULTS
The PLE values were closely correlated with the OAA/S scores (Spearman's Rho = 0.755; P < 0.001) to an extent comparable with the correlation between the BIS and OAA/S score (Spearman's Rho = 0.788; P < 0.001). The P(k) values of PLE and BIS were 0.731 and 0.718, respectively.
CONCLUSIONS
PLE is a new and reliable consciousness monitoring system for assessing the depth of sedation induced by propofol, which is comparable with the BIS.

Keyword

Consciousness monitor; Electroencephalography; Propofol; Sedation

MeSH Terms

Adult
Brachial Plexus Block
Consciousness Monitors
Electroencephalography
Entropy*
Humans
Propofol
Upper Extremity
Propofol