Fig. 6. Between-group comparison for the Bispectral Index (BIS). Minute 1 is the baseline measurement. The  axis shows the absolute difference of the mean change from baseline between the compared groups for every studied minute, together with the corresponding 95% confidence interval (CI). CONTROL = control group; KET = ketamine group; ROC = rocuronium group; ROC + KET = combined rocuronium–ketamine group. *  P < 0.05.