Comparison of 0.4 mg versus 0.6 mg of Intrathecal Nalbuphine as an Adjuvant to Hyperbaric Bupivacaine in Lower Abdomen and Lower Limb Surgeries

Background: Intrathecal administration of nalbuphine causes lower incidences of respiratory depression, nausea or vomiting, pruritus when compared to other opioids. Previous studies have compared various doses of nalbuphine including higher doses as an adjuvant to local anaesthetic. Aim and Objectives: To compare different doses of nalbuphine and to find out the most optimum amount. Material and Methods: One hundred twenty patients were assigned to Group A or B, each comprising of sixty patients after randomization. Group A, B patients received 0.4, 0.6 mg of nalbuphine respectively as an adjunct to 0.5% hyperbaric bupivacaine 3 ml. Primary outcomes were sensory, motor block duration, post-operative pain relief while secondary outcomes were assessment of haemodynamic parameters. Undesirable effects namely pruritus, shivering, nausea, vomiting were noted if any. Results: The onset of sensory, motor blocks didn't differ significantly (p=0.801, 0.616). However, the span of sensory, motor block, and analgesia after surgery were significantly more in group B (p=0.0005). Group A required more rescue analgesics (p=0.0005). The pulse rate was significantly lesser in group B, although it was clinically insignificant. The mean arterial pressures didn't differ significantly (P>0.05). Conclusion: Nalbuphine 0.6 mg significantly prolonged the span of sensory, motor blocks, and analgesia after surgery with stable haemodynamics and negligible incidence of nausea, vomiting. We believe that 0.6 mg is the optimum amount of nalbuphine as a supplement in spinal anaesthesia.