A Prospective Randomized Double-Blind Study Comparing the Efficacy of Intrathecal Dexmedetomidine and Intrathecal Fentanyl as Adjuvants to Hyperbaric Bupivacaine in Lower Limb Orthopedic Surgeries

Abstract

Background: Spinal anaesthesia is commonly used for lower limb orthopaedic surgeries; however, limited duration of postoperative analgesia remains a challenge. Intrathecal adjuvants such as fentanyl and dexmedetomidine enhance the quality and duration of spinal block. This study compared the efficacy and safety of intrathecal dexmedetomidine and fentanyl added to hyperbaric bupivacaine. Methods: This prospective, randomised, double-blind comparative study was conducted in the Department of Anaesthesiology, CSI Redfern Mission Hospital, Hassan, over a period of 6 months. A total of 75 patients undergoing elective lower limb orthopaedic surgeries under spinal anaesthesia were randomised into two groups. Group D (n=38) received intrathecal dexmedetomidine with hyperbaric bupivacaine, while Group F (n=37) received intrathecal fentanyl with hyperbaric bupivacaine. Onset and duration of sensory and motor block, duration of postoperative analgesia, rescue analgesic requirement, haemodynamic changes, and adverse effects were assessed. Results: Demographic characteristics were comparable between the two groups. The onset of sensory and motor blockade showed no significant difference. Duration of sensory block was significantly longer in the dexmedetomidine group compared with fentanyl (286.4 ± 32.5 vs 221.6 ± 28.9 min; p<0.001). Motor block duration was also prolonged with dexmedetomidine (258.3 ± 30.6 vs 198.7 ± 26.4 min; p<0.001). Postoperative analgesia duration was significantly higher in Group D (8.6 ± 1.2 vs 5.4 ± 1.0 hours; p<0.001), with reduced rescue analgesic requirement (23.7% vs 64.9%; p<0.001). Haemodynamic parameters were comparable between groups. Pruritus was significantly more frequent in the fentanyl group. Conclusion: Intrathecal dexmedetomidine provides superior prolongation of sensory and motor blockade with extended postoperative analgesia and reduced rescue analgesic requirement compared with fentanyl when used as an adjuvant to hyperbaric bupivacaine. It is an effective and safe alternative for spinal anaesthesia in lower limb orthopaedic surgeries.

Keywords: Dexmedetomidine, Fentanyl, Intrathecal adjuvant, Spinal anaesthesia, Hyperbaric bupivacaine, Orthopaedic surgery.