Accuracy Of Different Methods In Monitoring Depth Of Sedation Induced By Propofol: A Comparison Between Bispectral Index, Narcotrend Index, Auditory Evoked Potential Index And Index Of Consciousness

Objective: To compare the accuracy of bispectral index (BIS),Narcotrend index (NI), auditory evoked potential index (AAI) and index ofconsciousness (IoC) in monitoring the depth of sedation induced by propofol.Methods: Sixty ASA physical status ⅠorⅡ patients of both sexes, aged41-64yr, with body mass index20-30kg/m2, scheduled for elective surgeriesunder general anesthesia, were enrolled in the study. No patients receivedpremedication. After the patients entered the operating room, the mediancubital vein pathway was established, compound sodium chloride was infusedto maintain the fluid path unobstructed. The ECG, HR, SpO2and invasivemean arterial pressure (MAP) were monitored. The radial artery wascannulated under local anesthesia. The electrode of BIS, Narcotrend, AAI andIoC were placed, and the skin resistance was less than5k and the differencein the skin resistance between two electrodes of Narcotrend was less than3.5k. Propofol was given by target-controlled infusion (TCI) with the initialtarget effect-site concentration (Ce) of0.8μg/ml using Marsh pharmacokineticmodel, and then the Ce of propofol was increased by0.1μg/ml, and OAA/Swas performed. Before TCI of propofol, the values of BIS, NI, AAI and IoCwere recorded, which was the values of OAA/S score=5. During TCI ofpropofol, when OAA/S score was4,3,2and1in turn, the Ce of propofol wasrecorded, and the values of BIS, NI, AAI, and IoC were also recorded in5sand averaged using a random number table. The parameters for vital signswere maintained within the normal range. The correlation between BIS, NI,AAI and IoC values and Ce of propofol and OAA/S score was performedusing Spearman rank correlation analysis. Linear correlation analysis was performed to evaluate the relationship between BIS, NI, AAI, and IoC valuesand Ce of propofol. U test was used to analyze the correlation coefficients.Results: The correlation coefficients of BIS, NI, AAI, IoC values and Ceof propofol with the OAA/S scores were rBIS-OAA/S=0.905, rNI-OAA/S=0.960,rAAI-OAA/S=0.892, rIoC-OAA/S=0.942and rCe-OAA/S=－0.949, respectively(P<0.05). The correlation coefficients of BIS, NI, AAI and IoC values with theCe of propofol were rBIS-Ce=－0.829, rNI-Ce=－0.886, rAAI-Ce=－0.791andrIoC-Ce=－0.881, respectively (P<0.05). There was no significant differencebetween rBIS-OAA/S, rNI-OAA/S, rAAI-OAA/Sand rIoC-OAA/Sand between rBIS-Ce, rNI-Ce,rAAI-Ceand rIoC-Ce(P>0.05).Conclusions: BIS, NI, AAI and IoC can accurately monitor the depth ofsedation induced by propofol in middle-aged patients with non-noxiousstimuli and there are no differences in the accuracy between BIS, NI, AAI andIoC.