Comparison of the Effects of Bupivacaine and Levobupivacaine Used in Spinal Anesthesia on Propofol Requirement in BIS Guided Sedation

Objective: This study was designed to compare the effects of equivalent doses of bupivacaine and levobupivacaine on propofol requirement in BIS guided sedation under spinal anesthesia. Material and Methods: Spinal anesthesia was performed on seventy patients scheduled for elective lower limb surgery with 3 mL’s of either isobaric bupivacaine (Group B) or plain levobupivacaine (Group L). Five minutes after induction of spinal anesthesia, propofol infusion was started at 100 μg/kg/min and titrated to maintain bispectral index (BIS) score in the range of 65-75. Onset (to reach BIS ≤ 75) and recovery (the time from cessation of propofol infusion until BIS=90) time for sedation, and total propofol consumption during this time interval were recorded as well as time to recovery from sensory and motor block, length of stay (LOS) and sedation scores (OAA/S) in the postanesthesia care unit (PACU). Data were analyzed with One way ANOVA, Mann Whitney-U, Student’s t and x tests. Results: BIS was significantly decreased in Group B compared to Group L at 10 and 15 min after spinal anesthesia (p<0.01). The maximum sensory block level was higher, while time to reach maximum motor block level was shorter in Group B (p<0.05, p<0.001 respectively). Offset time of sensory and motor block, recovery time and LOS in PACU were significantly increased in Group L (p<0.05). Conclusion: Plain bupivacaine provides higher sensory block with faster onset of motor block, independent of propofol requirement as assessed by BIS monitorization.