Influence of (S)-Ketamine on the Bispectral Index and Electroencephalogram during Total Intravenous Anesthesia: A Randomized Clinical Trial

Background: This study aims to evaluate the influence of different doses of (S)-ketamine on bispectral index (BIS) and electromyographic power (pEMG). Method: Forty participants, submitted to controlled venous effector site anesthesia, were randomly distributed into 5 groups. In the k0 control group, participants did not receive (S)-ketamine; k1, k2, k3, and k4 received (S)-ketamine 200 µg.kg-1 iv followed by a continuous infusion of 100, 200, 300, and 400 µg.kg-1 h-1, respectively. In each group, 11 moments were evaluated: M0, before anesthetic induction, M1, 10 minutes after anesthesia stabilization with BIS between 45 and 55, and M2 to M10, 3, 6, 9, 12, 15, 18, 21, 24, and 27 minutes after (S)-ketamine. At all moments, BIS and pEMG values were recorded. An ANOVA was used for repeated measures, and the p-value was adjusted for multiple comparisons by Tukey’s test, considering p< 0.05 as significant. Results: No significant changes (p> 0.05) were observed at each moment after M0 by comparing the mean BIS and pEMG values between all groups. Conclusion: Electroencephalographic parameters (BIS and pEMG) are not significantly influenced when this (S)-ketamine infusion model and total intravenous anesthesia are performed.