Background: We compared the propofol requirements and recovery times when either the bispectral index (BIS) monitor or the cerebral state monitor (CSM) is used to guide propofol anaesthesia.
Methods: Forty patients undergoing laparoscopic cholecystectomy were studied. All patients were monitored with both monitors and were randomly allocated into two groups according to the monitor used to titrate propofol administration. Propofol was administered to maintain BIS or CSM within 40 and 60. Propofol consumption and clinical markers of recovery were assessed after surgery.
Results: In the CSM group, the values of cerebral state index (CSI) and BIS were 47 (5) and 38 (6), respectively (P=0.00054). In the BIS group, the values of CSI and BIS were 47 (5) and 45 (2), respectively (P=0.15). In the BIS group, the total amount of propofol used was lower [109 (20) microg kg(-1) min(-1)] than in the CSM group [130 (27) microg kg(-1) min(-1)] (P=0.018). The time to eye opening was lower in the BIS [7.2 (3.5) min] than in the CSM group [10.7 (6.6)] (P=0.038). There were no differences in fentanyl consumption, or in other clinical markers of recovery.
Conclusions: Compared with BIS, propofol anaesthesia guided with CSI resulted in 20% higher propofol doses. This, however, does not lead to clinically relevant differences in recovery times.