Comparison of the characteristics of sedation using target-controlled infusion and manual infusion of propofol in patients undergoing lower limb surgery under spinal anaesthesia; a randomised controlled trial

Background: Conscious sedation during spinal anaesthesia can be achieved by administering propofol using manual controlled infusions (MPI) or target-controlled infusions (TCI). We compared the characteristics of sedation with propofol administered by MPI and TCI in patients undergoing lower limb surgery under spinal anaesthesia. Methods: A total of 60 patients aged 18-60 years with American Society of Anaesthesiologists physical status 1 and 2 who were scheduled for elective lower limb surgery of an anticipated duration of 1-2 h under spinal anaesthesia were enrolled. Participants were randomly allocated in 1:1 to either Group TCI or Group MPI to receive propofol sedation to maintain OAA/S 3. The primary outcome measure was the recovery time. Secondary outcomes were time to reach the desired level of sedation (OAA/S 3) and the total dose of propofol consumed. Main results: The mean recovery time was 6.23 f 1.63 min in the TCI group and 7.30 f 1.44 min in the MPI group (p = 0.010). The total dose of propofol used in the TCI group (230.07 f 83.77) was significantly higher than in the MPI group (162.33 f 62.29) with a p = 0.001. A very strong positive correlation was observed between OAA/S and BIS in the TCI group (r = 0.969) as well as in the MPI group (r = 0.955) with a p < 0.001. Conclusion: With the study design employed, TCI was associated with a faster recovery and MPI with less propofol consumption. There was a high correlation between OAA/S and BIS values.