Electroencephalographic approximate entropy changes in healthy volunteers during remifentanil infusion.
BACKGROUND
The aim of this study was to investigate the independent effect of remifentanil on the approximate entropy (ApEn) in frontoparietal montages. The authors investigated which montages were relevant to assess the remifentanil effect on the electroencephalogram. Spectral edge frequency and the canonical univariate parameter were used as comparators.


METHODS
Twenty-eight healthy volunteers were enrolled. With recording of the electroencephalogram at the F3, F4, Cz, P3, and P4 montages, remifentanil was infused at the rate of 1-8 mug . kg . min for 15-20 min. The relation between remifentanil concentration and the electroencephalographic parameters were tested by Spearman correlation. Signal-to-noise ratio, artifact robustness, coefficient of variation of the median baseline and maximal electroencephalographic effects, and ratio of average maximal electroencephalographic effect to interindividual baseline variability were measured. The performance of ApEn as an index of remifentanil effect site concentrations was tested by prediction probability.


RESULTS
Approximate entropy showed significant correlation (R = -0.6465, P < 0.0001) with remifentanil concentration. It provided comparable signal-to-noise ratio, artifact robustness, and ratio of average maximal electroencephalographic effect to interindividual baseline variability to 95% spectral edge frequency. The coefficients of variation of the median baseline and maximal electroencephalo graphic effects were smallest in ApEn. Parietal montages showed higher ratios of average maximal electroencephalographic effect to interindividual baseline variability for all electroencephalographic parameters and lower coefficients of variation of the baseline values for ApEn and 95% spectral edge frequency than frontal montages. The prediction probability of ApEn was 0.7730.


CONCLUSIONS
Approximate entropy derived from a parietal montage is appropriate for the assessment of the remifentanil effect on the electroencephalogram.
Noh
Gyu-Jeong
GJ
Department of Anesthesiology and Pain Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
Kim
Kye-Min
KM
Jeong
Yong-Bo
YB
Jeong
Seong-Wook
SW
Yoon
Hee-Suk
HS
Jeong
Sung-Moon
SM
Kang
Sung-Hong
SH
Linares
Olinto
O
Kern
Steven E
SE
D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology; D000465:Algorithms; D000701:Analgesics, Opioid / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D016477:Artifacts; D001499:Bayes Theorem; D003627:Data Interpretation, Statistical; D004569:Electroencephalography / Q000187:drug effects* / Q000706:statistics & numerical data; D019277:Entropy; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007261:Infusions, Intra-Arterial; D007262:Infusions, Intravenous; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D010880:Piperidines / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D000077208:Remifentanil
D000701:Analgesics, Opioid; D010880:Piperidines; D000077208:Remifentanil