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

Background: Nalbuphine is a opioid, structurally related to oxymorphine, highly lipid soluble opioid with an agonist action at the K- opioid receptor and antagonist activity at the μ receptor. Aim: To compare the characteristics of Nalbuphine effects with different doses with bupivacaine and bupivacaine alone in subarachnoid block for patients undergoing elective lower abdominal surgeries. Methods:A double blind prospective randomized control clinical study was conducted on120 patients of 18 to 60 years age, either sex and American society of anaesthesiologist (ASA)Ⅰ/Ⅱ undergoing elective lower limb surgeries under planned spinal anaesthesia were included and randomly allocated into 4 equal groups (n=30 each), to receive spinal anaesthesia with - 12.5mg of 0.5% heavy bupivacaine(group A), 12.5mg of 0.5% heavy bupivacaine along with 0.4mg nalbuphine (group B), 12.5mg of 0.5% heavy bupivacaine along with 0.6mg nalbuphine (group C)and 12.5mg of 0.5% heavy bupivacaine along with0.8mg nalbuphine (group D). The patients were evaluated with respect to various sensory and motor characteristics, duration of postoperative analgesia and adverse effects. Results: All the groups were comparable with respect to demographic profile. There was clinically significant early onset of sensory block with group C 2.5±0.78 min Vs 2.7±0.69,2.6±0.74 and 2.6±0.62 min in group A,B,D respectively with p(0.794). Time to attain highest level of sensory block with group C 7.8±0.36 min Vs 7.9±0.46,7.9±0.45 and 7.8±0.49 min in group A,B,D respectively with p(0.676). There was prolongation of duration of sensory block with group C 180±4.4 min Vs 96±6.7,164±9.9,187±2.4 min in group A,B,D groups respectively with p(<0.001). There was significant prolongation of motor blockade with group C 171.2±14.2 min Vs 164.4±12.8, 166.8±15.7, 172.5±11.1 min in A, B, D groups respectively with p(0.08). Total duration of complete analgesia with group C is 286.4±13.6 min Vs 182.6±6.72, 240.2±13.87, 292.3±17.5 min in group A,B,D respectively. The present study shown that intrathecal doses of nalbuphine namely 0.4 &0.8 mgs along with 0.6 mg to find out the optimal intrathecal dose which has maximal duration of post op analgesia with minimal adverse effects. Overall there was less adverse effects in group C patients with 0.6mg Nalbuphine as an adjuvant to 0.5/. heavy bupivacaine in spinal anaesthesia. Conclusion: 0.6 mg Nalbuphine as an adjuvant to spinal bupivacaine is more effective in terms of duration of sensory and motor blockade, postoperative analgesia and having less side effects. Nalbuphine provide very good quality of analgesia and prolongs duration of analgesia intraoperative and postoperative period. Adverse effects of Nalbuphine are minimal and well manageable. It provides stable hemodynamic. It does not produce respiratory depression. Dosage up to 0.8mg of nalbuphine may be used without any major adverse effects