Objective: To compare the analgesic effect of different doses of nalbuphine when added to bupivacaine in spinal anaesthesia. To compare the onset of sensory blockade (time taken form 3, 5 min and then every 5 min until the end of the procedure.

Methods: 100 ASA grade 1 and 2 patients grouped into group A, group B, group C and group D randomly. Age group of 18-60 years. Patient undergoing elective lower abdominal and orthopedic surgery received with Group A : included 25patients with 0.5% hyperbaric bupivacaine 3 cc (15mg) + N.S. 0.2 ml. Group B: included 25 patients with 0.5% hyperbaric bupivacaine (3 cc) 15 mg + 0.8mg nalbuphine + N.S. 0.2 ml. Group C: included 25 patients with 0.5% hyperbaric bupivacaine (3 cc) 15 mg + 1.6mg nalbuphine + N.S. 0.2 ml. Group D: included 25 patients with 0.5% hyperbaric bupivacaine (3 cc) 15 mg + 2.4 mg nalbuphine + N.S. 0.2 ml.

Results: The mean sensory onset of study subjects in group A, B, C and D were 8.4±0.5, 5±0.9, 5.6±1 and 8.2±1.4 respectively and this difference was statistically significant. The mean motor onset of study subjects in group A, B, C and D were 10.2±0.7, 6.8±0.9, 6.1±1.2 and 8.6±1.1 respectively and this difference was statistically significant. The mean sensory duration of study subjects in group A, B, C and D were 176.8±29.3, 282±6.8, 300.2±6.6 and 286.2±9.8 respectively and this difference was statistically significant. The mean time for maximum sensory level of study subjects in group A, B, C and D were 11.5±1, 8.8±0.8, 5.6±1.6 and 8.2±1.2 respectively and this difference was statistically significant. The mean T 10 time of study subjects in group A, B, C and D were 8.5±0.5, 8.7±0.7, 5.6±1.6 and 8.6±1 respectively and this difference was statistically significant. The mean time for 2 segment regression of study subjects in group A, B, C and D were 76.6±2, 92.2±2.3, 95.8±3 and 90.6±4.4 respectively and this difference was statistically significant. The mean motor duration of study subjects in group A, B, C and D were 179.8±8.9, 184.6±6, 203.2±7 and 187±9.9 respectively and this difference was statistically significant. The mean analgesic duration of study subjects in group A, B, C and D were 175.8±4.1, 271.1±7.8, 303.8±9.9 and 279±10.7 respectively and this difference was statistically significant.

Conclusion: We came to conclusion that 0.5% hyperbaric bupivacaine (15mg) with nalbuphine (0.8mg, 1.6 mg, 2.4 mg) in subarachnoid block. Therefore addition of 1.6 mg nalbuphine to 15mg of 0.5% hyperbaric bupivacaine 15 mg in subarachnoid block can be considered safe with minimum complication, and provides excellent quality and longer duration of postoperative analgesia with good sedation compared with 0.8 mg and 2.4 of nalbuphine. So it is useful for prolonged duration of postoperative analgesia.