Accuracy of anesthesia index for monitoring depth of sedation induced by propofol: a comparison with bispectral index

Abstract

Objective To evaluate the accuracy of anesthesia index(AI)for monitoring depth of sedation induced by propofol. Methods Thirty patients of both sexes, aged 41-64 yr, with body mass index of 20-30 kg/m2, of American Society of Anesthesiologists physical statusⅠorⅡ, scheduled for elective surgery 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 1.2 μg/ml using Marsh pharmacokinetic model, and then the Ce of propofol was increased in 0.3 μg/ml increment, and Observer′s Assessment of Alertness/Sedation(OAA/S)score was evaluated.OAA/S score was 5 before TCI of propofol.When OAA/S score reached 4, 3, 2 and 1 in turn during TCI of propofol, the bispectral index(BIS), AI and corresponding Ce were recorded. Results The correlation coefficients of BIS, AI and Ce levels with the OAA/S scores were rBIS-OAA/S=0.962, rAI-OAA/S=0.960 and rCe-OAA/S =-0.795, respectively(P 0.05). Conclusion AI can accurately monitor the depth of sedation induced by propofol in adult patients without noxious stimuli and there is no significant change in the accuracy in comparison with BIS. Key words: Electroencephalography; Monitoring, physiologic; Propofol; Conscious sedation