“Comparison of nalbuphine hydrochloride and fentanyl as an adjuvant to bupivacaine for spinal anesthesia in lower abdominal surgeries:” A randomized, double-blind study

Background and Aims: Opioids have been favored as adjuvants to local anesthetics during spinal anesthesia. Nalbuphine, a μ-receptor antagonist and ĸ-receptor agonist, seems to be a suitable adjuvant to local anesthetics. The aim of this study was to compare postoperative analgesia and adverse effects of nalbuphine and fentanyl when used as an adjuvant to hyperbaric bupivacaine during spinal anesthesia. Materials and Methods: Sixty patients belonging to the American Society of Anesthesiologists Physical Status I and II were randomly allocated into two groups of thirty each. Patients in bupivacaine nalbuphine group (Group BN) received 0.8 mg (0.3 ml) of nalbuphine with 12.5 mg (2.5 ml) of 0.5% hyperbaric bupivacaine diluted to 3 ml and bupivacaine-fentanyl group (Group BF) received 25 μg (0.5 ml) of fentanyl with 12.5 mg (2.5 ml) of 0.5% hyperbaric bupivacaine. Patients were assessed for hemodynamic changes, sensory and motor block, early postoperative analgesia, and adverse effects. Results: Onset, duration of sensory and motor block, and duration of effective analgesia were comparable between both groups. Postoperative visual analog scale score was 4.8 ± 1.12 in Group BN, and in Group BF, it was 3.86 ± 1.04 which was statistically highly significant (P = 0.0007). The number of patients demanding rescue analgesia in early postoperative period was 18 (60.0%) in Group BN and 7 (23.33%) in Group BF which was statistically significant (P = 0.004). Conclusion: Fentanyl was more efficient than nalbuphine in providing early postoperative analgesia when used as an adjuvant to hyperbaric bupivacaine.