Background: Subarachnoid block is the most preferred technique for anaesthetic management for lower limb surgeries. Various adjuvants have been used to improve the efficacy local anaesthetics by hastening the onset and prolonging the duration of sensory and motor block. The present study aims to compare the efficacy of intrathecal nalbuphine with butorphanol as adjuvant to 0.5% hyperbaric bupivacaine for lower limb surgery.

Methods: 90 patients belonging to ASA status I and II of either sex were randomly divided into three groups of 30 each to receive either butorphanol 25 µg (Group A) or nalbuphine 400 mcg (Group B) or normal saline 0.5 ml (Group C) with 2.5 mL 0.5% hyperbaric bupivacaine, making intrathecal drug volume to 3mL in each group. Sensory and motor block characteristics in terms of time to onset and duration were recorded as the primary end points. Drug related side effects of pruritus, nausea/vomiting, and respiratory depression were recorded as the secondary outcomes.

Results: The three groups were comparable regarding the demographic profile. The time to onset of sensory block was shortened in patients of group A and B as compared to group C, more so in group A. The mean time of 2 dermatomal regression was significantly more in Group B as compared to Group A and Group C (p=0.003, p<0.001) and significantly more in Group A as compared to Group C (p<0.001). Onset of motor block and time required to attain complete motor block (motor bromage 2 and 3 respectively) were comparable between the three groups and statistically not significant Duration of motor block was significantly more in group B as compared to Group A and Group C (p<0.001, p<0.001) and comparable between Group A and Group C .Furthermore, duration of motor block was maximum in Group B as compared to Group A (<0.001). No drug related side effects were observed in either group.

Conclusions: Intrathecal Butorphanol 25 mcg showed faster onset of sensory block whereas nalbuphine 400 mcg showed prolonged duration of sensory and motor block as adjuvant to hyperbaric bupivacaine 0.5%.