Accuracy of different methods in monitoring depth of sedation induced by propofol: a comparison between BIS, NI, IoC and AAI

Abstract

Objective To compare the accuracy of bispectral index(BIS), Narcotrend index(NI), index of consciousness(IoC)versus auditory evoked potential index(AAI)in monitoring the depth of sedation induced by propofol. Methods Sixty ASA physical status Ⅰ or Ⅱ patients of both sexes, aged 41-64 yr, with body mass index 20-30 kg/m2, scheduled for elective surgeries under general anesthesia, were enrolled in the study.Propofol was given by target-controlled infusion(TCI)with the initial target effect-site concentration(Ce)of 0.8 μg/ml using Marsh pharmacokinetic model, and then the Ce of propofol was increased by 0.1 μg/ml, and OAA/S was performed.Before TCI of propofol, the values of BIS, NI, IoC and AAI were recorded, and at the same time the value of OAA/S score was 5.During TCI of propofol, when OAA/S score reached 4, 3, 2 and 1 in turn, the Ce of propofol was recorded, the sequence for determination of the values of BIS, NI, IoC and AAI was determined using a random number table, and the values were then recorded for 5 s after the values were stable and then averaged.The parameters for vital signs were maintained within the normal range.Pearson correlation of BIS, NI, IoC and AAI values with Ce of propofol was analyzed. Results The correlation coefficients of BIS, NI, IoC and AAI values with the Ce of propofol were rBIS-Ce=-0.829, rNI-Ce=-0.886, rIoC-Ce=-0.881 and rAAI-Ce=-0.791, respectively.There was no significant difference between rBIS-Ce, rNI-Ce, rIoC-Ce and rAAI-Ce. Conclusion There are no significant differences in the accuracy of BIS, NI, IoC or AAI in monitoring the depth of sedation induced by propofol in middle-aged patients with non-noxious stimuli. Key words: Monitoring, physiologic; Electroencephalography; Evoked potentials, auditory; Conscious sedation; Propofol; Narcotrend; Index of consciousness