Effect of Clonidine And/or Fentanyl in Combination with Intrathecal Bupivacaine for Lower Limb Surgery

Background And Aims: Various adjuncts to local anesthetics have been used with the purpose of improving the quality of subarachnoid block. This randomized double-blind study was conducted to evaluate the efficacy of adding clonidine to bupivacaine and bupivacaine-fentanyl combination.

Material And Methods: A total of 100 patients scheduled for surgery under spinal anesthesia were randomly allocated into four groups (n = 25 each) to receive intrathecal bupivacaine 7.5 mg plus normal saline 0.5 ml (group BS), intrathecal bupivacaine 7.5 mg, and fentanyl 25 μg (group BF), intrathecal bupivacaine 7.5 mg and clonidine 75 μg (group BC), intrathecal bupivacaine 7.5 mg, clonidine 37.5 μg, and fentanyl 12.5 μg (group BCF). The time of onset and duration of sensory block, highest dermatome level of sensory block, time of onset of motor block, time to complete motor block recovery and duration of spinal anesthesia, intraoperative and postoperative hemodynamics and side effects if any were recorded. VAS, total number of patients who were administered supplemental analgesic in each group and the total amount of supplemental analgesic administered in the next 24 h was quantified and documented in all the groups.

Results: The time of onset of sensory block (min) in groups BS, BC, BCF, and BF was 10.80 ± 2.26, 10.20 ± 1.00, 10.00 ± 0.00, and 13.80 ± 2.61 respectively, thus onset of sensory block was significantly earlier in groups BC and BCF. Similarly, onset of motor block was also quicker in groups BC and BCF. Time of requirement of supplemental analgesia was 135.20 ± 12.70 min, 199.2 ± 21.92 min, 209.80 ± 26.32 min, and 208.00 ± 26.58 min in groups BS, BF, BC, and BCF respectively. Intraoperative and postoperative changes in heart rate, mean arterial blood pressure, oxygen saturation, and respiratory rate were comparable. Sedation scores were significantly higher in group BC. Pruritus was only observed in groups BF and BCF. Mean nausea vomiting scores were comparable in all groups.

Conclusion: We conclude that the addition of clonidine in doses of 75 μg and 37.5 μg to low-dose bupivacaine and bupivacaine-fentanyl prolongs the sensory and motor block while increasing the duration of postoperative analgesia without significant side-effects.