Comparison of Analgesic Efficacy of Nalbuphine and Fentanyl as Adjuvants to Intrathecal Hyperbaric Bupivacaine in Patients undergoing Lower Limb Orthopaedic Surgeries: Randomised Clinical Trial

Introduction: Postoperative pain management poses a major challenge in patients who undergo lower limb orthopaedic surgeries. Methods that reduce the requirements of systemic analgesics and have minimal adverse effects on haemodynamic stability are the need of the hour. Nalbuphine, a kappa agonist/partial μ antagonist can be utilised in spinal anaesthesia as an auxiliary to local anaesthetic.

Aim: To evaluate the efficiency of intrathecal hyperbaric bupivacaine versus nalbuphine plus fentanyl as adjuvants in patients undergoing lower limb orthopaedic surgeries.

Materials and Methods: This prospective randomised clinical trial comprised 70 American Society of Anaesthesiologists (ASA) grade I and II patients aged between 18-60 years who had been posted for elective lower limb orthopaedic operations. Patients were randomly assigned to either Group NB (intrathecal bupivacaine with nalbuphine) or Group FB (Intrathecal bupivacaine with fentanyl). Onset and duration of sensory and motor block, haemodynamic alterations, side-effects, and requirement for systemic analgesics in the postoperative period were examined.

Results: There was no statistically significant difference in beginning of sensory and motor blockage between the two groups. In comparison to group FB, group NB’s sensory blockade lasted substantially longer (126.06±6.52 minutes vs. 103.34±3.7 minutes; p-value <0.001). In group NB, the length of the motor block was considerably longer (p-value <0.001). When compared to patients in group FB (230.83±7.98 minutes), patients in group NB experienced analgesia for a mean time of 278.31±9.58 minutes, which was noticeably longer. There was no discernible difference between group NB and group FB (p-value >0.05) in terms of symptoms such as nausea, vomiting, bradycardia, and hypotension throughout the intraoperative period.

Conclusion: In patients scheduled for elective lower limb orthopaedic procedures, intrathecal nalbuphine 1 mg as an adjuvant to 0.5% hyperbaric bupivacaine for subarachnoid block extend the duration of sensory block, motor block, and the postoperative analgesia more successfully than intrathecal fentanyl 25 μg.