A comparison of analgesic effect of different doses of intrathecal nalbuphine hydrochloride with bupivacaine and bupivacaine alone for lower abdominal and orthopedic surgeries

Background: Nalbuphine is a synthetic opioid with mixed agonist-antagonist action, when added as adjuvant to intrathecal bupivacaine acts on kappa receptors in the dorsal horn of the spinal cord producing analgesia. Aim: To evaluate the onset of sensory block, hemodynamic changes, duration and quality of analgesia, and adverse effects of different doses of nalbuphine with bupivacaine for spinal anesthesia. Materials and Methods: Randomized double blind study done on 100 patients undergoing lower abdominal and lower limb orthopedic surgeries under subarachnoid block. Patients were randomly allocated to four groups receiving either intrathecal 15 mg of bupivacaine + 0.5 mL normal saline alone or 15 mg of bupivacaine with either of nalbuphine 0.8, 1.6, and 2.5 mg + 0.5 mL normal saline. Results: The mean visual analogue scale score in group A is 4.08 ± 0.5 and in groups B, C, and D are 3.4 ± 0.4, 3.5 ± 0.5, and 3.5 ± 0.5, respectively. The duration of analgesia in group A is 190.4 ± 20.0 and in groups B, C, and D were 322.4 ± 31.1, 319 ± 39.8 and 317.8 ± 47.5. The quality of analgesia was good in 72%-76% and excellent in 16%-28% in groups B, C, and D and poor 28% to satisfactory 72% in group A. Conclusion: Addition of 0.8 mg of nalbuphine to 0.5% bupivacaine for subarachnoid block provides excellent analgesia with longer duration of action compared with 1.6 and 2.4 mg of nalbuphine.