Background and objective: Providing a spinal block with preferential distribution to operative side is a useful technique. This study aimed to determine the incidence and suitability of unilateral spinal block, hypotension and recovery profile by 7.5 mg of 0.5% hyperbaric bupivacaine alone or with fentanyl/clonidine for knee or below knee orthopaedic surgery of moderate duration.
Methods: 120 patients undergoing orthopaedic surgery of lower limb received 7.5 mg of 0.5% hyperbaric bupivacaine intrathecally with 25 μg of fentanyl (Group BF), 25 Regularg of clonidine (Group BC) or 0.5 ml of saline (Group BS). Block characteristics, unilaterality, haemodynamic changes and recovery profile was noted.
Results: Unilateral block was seen in more than 70% of patients in all the groups (p=0.057). Time of regression of sensory block to L2 level (133 ± 18, 187 ± 19, 182 ± 18 mins respectively in groups BS, BF and BC) and time of first postoperative analgesia (245 ± 27, 324 ± 24, 318 ± 22 mins respectively in groups BS, BF,BC, p<0.001) was prolonged in groups BF and BC. Motor block was prolonged in group BC only. Cardiovascular parameters were stable throughout, in all the groups.
Conclusion: 7.5 mg of hyperbaric bupivacaine alone or with fentanyl or clonidine produced predominantly unilateral spinal anaesthesia in more than 70% patients in the entire group with stable cardiovascular parameters. Addition of fentanyl or clonidine did not influence unilaterality or block characteristics but prolonged postoperative analgesia. Unilateral spinal block is suitable for moderate duration orthopaedic surgery of knee or below knee.