Intrathecal nalbuphine vs. buprenorphine as an adjuvant in lower limb orthopedic surgeries: a prospective randomized controlled study

This study aimed to compare the efficacy of intrathecal nalbuphine and buprenorphine as an adjuvant to heavy bupivacaine (0.5%) for spinal anesthesia in lower limb orthopedic surgeries to improve the quality of spinal anesthesia (onset, duration, and side effects) and prolongation of postoperative analgesia. Sixty patients were recruited into this single-centered, double-blinded, hospital-based, prospective, comparative study conducted in 2017-2018. They were randomly and equally (n = 30) allocated into two groups: nalbuphine group which received 0.5 mL (0.8 mg) of nalbuphine with 3 mL of heavy (0.5%) hyperbaric bupivacaine and buprenorphine group which received 0.5 mL (60 mg) of buprenorphine with 3 mL of heavy hyperbaric bupivacaine. Intraoperatively, onset and duration of blockade (motor and sensory), and time for first dose of rescue analgesia were recorded in both groups at regular intervals. Heart rate, blood pressure, Visual Analogue Scale score and side effects were also recorded postoperatively for 12 hours. The demographic parameters, time of onset of sensory block and motor block, and duration of motor block were comparable between nalbuphine and buprenorphine groups. The duration of sensory block in the buprenorphine group was longer than in the nalbuphine group. Time to the first dose of rescue analgesia was delayed in buprenorphine group as compared to nalbuphine group. In both groups maximum patients achieved maximum height of sensory block at 90 minutes. There were significant differences in the mean heart rate and blood pressure between buprenorphine and nalbuphine groups. Nalbuphine group patients achieved a Visual Analogue Scale score > 4 earlier as compared to buprenorphine group. Few side effects were observed in both groups. Intrathecal buprenorphine is a better adjuvant to 0.5% bupivacaine in the spinal anesthesia for lower limb orthopedic surgeries, as it provides longer sensory block and delayed administration of first dose of rescue analgesia with negligible side-effects.