Comparison of intravenous dexmedetomidine versus ketamine-dexmedetomidine combination on spinal block characteristics in patients undergoing lower limb orthopaedic surgery - A randomised clinical trial.

BACKGROUND AND AIMS: One major limitation of the spinal block remains the inability to extend the duration of the block intraoperatively unless planned before with spinal or epidural catheters and/or intrathecal additives. This study was designed to compare the effects of intravenous dexmedetomidine versus low-dose ketamine-dexmedetomidine combination infusion on spinal anaesthesia in lower limb orthopaedic surgeries.

METHODS

This randomised study was conducted in 60 patients scheduled for unilateral lower limb surgeries under spinal anaesthesia. Patients were randomised into Group D (n = 30) (0.5 µg/kg of intravenous (IV) dexmedetomidine bolus followed by maintenance infusion at 0.5 µg/kg/h) and Group LKD (n = 30) (IV bolus of 0.5 µg/kg of dexmedetomidine and 0.2 mg/kg of ketamine, followed by maintenance infusions of dexmedetomidine and ketamine at 0.5 µg/kg/h and 0.2 mg/kg/h, respectively). Ramsay Sedation Scale score of 3-4 was maintained. The t-test or the Wilcoxon-Mann-Whitney U test was used to compare the parameters between groups.

RESULTS

The mean sacral segment 1 (S1) regression time was 390.3 [standard deviation (SD):84.38] [95% confidence interval (CI): 360.13, 420.53] versus 393.23 (SD: 93.01) (95% CI: 363.04, 423.43) min in Group D versus Group LKD respectively ((P = 0.701). The number of episodes of hypotension was significantly higher in Group D (19 patients) compared to Group LKD (nine patients) (P = 0.001). Pre- and postoperative stress markers (24 h) and the incidence of postoperative nausea and shivering were comparable between the two groups (P > 0.05). Tramadol requirement in the postoperative period was significantly less in Group LKD compared to Group D (P = 0.003).

CONCLUSION

The duration of S1 regression was similar between group dexmedetomidine (Group D) and group low-dose ketamine and dexmedetomidine (Group LKD).