[Effect of propofol at different effect-site concentrations on approximate entropy of transient evoked otoacoustic emission signals in adults].
OBJECTIVE
To study the effect of propofol at different effect-site concentrations on approximate entropy (ApEn) of transient evoked otoacoustic emission (TEOAE) signals in adults and investigate the possibility of using ApEn for monitoring anesthesia depth.


METHODS
Fifteen ASA class I or II patients (aged 18-49 years with normal hearing) undergoing elective surgery under general anesthesia were enrolled in this study. Anesthesia was maintained with target-controlled infusion of propofol. With the effect-site concentrations of 1, 2, 3 and 4 microg/ml, TEOAE signals were monitored and recorded before and after anesthesia. ApEn of TEOAE in 4 frequency ranges (0-2, 1-3, 2.5-4.5, and 4-6 kHz) were calculated using MATLAB software.


RESULTS
The ApEn of TEOAE in different frequency ranges showed no significant differences at the same effect-site concentration of propofol, or at different effect-site concentrations in the same frequency range (P>0.05).


CONCLUSIONS
Anesthesia with propofol at different effect-site concentrations does not obviously affect ApEn of TEOAE signals in adults, and ApEn can not be used as the indicator for evaluating the depth of anesthesia.
Zhang
Xin-jian
XJ
Department of Anesthesiology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China. zaj2006@yahoo.com.cn
Gu
Miao-ning
MN
Xiao
Jin-fang
JF
D000293:Adolescent; D000328:Adult; D018686:Anesthetics, Intravenous / Q000494:pharmacology*; D019277:Entropy; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods; D017084:Otoacoustic Emissions, Spontaneous / Q000187:drug effects*; D015742:Propofol / Q000494:pharmacology*; D055815:Young Adult
D018686:Anesthetics, Intravenous; D015742:Propofol