Objective: To evaluate the accuracy of cerebral state index (CSI) as an indicator of anesthesia depth in patients in the induction of anesthesia with target-controlled infusion of propofol.
Methods: Forty ASA (American Society of Anesthesiologists) I approximately II patients scheduled for an operation under general anesthesia were anesthetized with target-controlled infusion of propofol. Target plasma concentration was 0. 5 mg/L at the beginning, and increased by 0. 5 mg/L every 5 minutes, till 5 minutes after the level of MOAA/S (modified observer's assessment of alertness/sedation) was 0. The CSI, mean arterial pressure (MAP), heart rate (HR), MOAA/S level, and the effect-site concentration of propofol were recorded.
Results: (1) CSI values declined with the decrease of MOAA/S levels. CSI values were statistically different between level 0 and 1, level 1 and 2, level 3 and 4, level 4 and 5 of MOAA/S (P < 0.05). The difference of MAP had statistical significance between level 3 and level 2 of MOAA/S (P < 0.05). HR values had no statistical difference between the two levels of MOAA/S (P > 0.05). (2) The spearman rank correlation co-efficients between CSI, MAP, HR and the level of MOAA/S were 0.929, 0.421, and 0.085, respectively. The prediction probabilities (Pk) to differentiate different levels of MOAA/S for CSI, MAP, and HR were 0.94, 0.67, and 0.54, respectively. (3) There was linear regression relationship between CSI and the effect-site concentration of propofol (the coefficient of determination R2 was 0. 833, P < 0.01).
Conclusion: During the induction of patients with target-controlled infusion of propofol, the CSI is accurate as an indicator of awakeness and different levels of consciousness after anesthesia, and can reliably predict the anesthesia depth.