COMPARISON OF INTRATHECAL NALBUPHINE IN DIFFERENT DOSES AS AN ADJUVANT TO HYPERBARIC BUPIVACAINE IN PERCUTANEOUS NEPHROLITHOTOMY: A RANDOMIZED CONTROLLED STUDY

Abstract

Background and Objectives- Percutaneous nephrolithotomy (PCNL) is a well-established procedure for kidney stone removal, often performed under spinal anesthesia. Nalbuphine, a mixed κ-opioid receptor agonist and μ-opioid receptor antagonist, has demonstrated effective analgesic properties with minimal side effects. This study compares the effects of two different doses of intrathecal nalbuphine (0.5 mg vs. 1 mg) as adjuvants to hyperbaric bupivacaine in patients undergoing PCNL.

Methods- A randomized controlled trial was conducted with 60 ASA I and II patients scheduled for elective PCNL under spinal anesthesia. Participants were randomly assigned to two groups (n=30 each): Group 1: 15 mg (3 mL) of 0.5% hyperbaric bupivacaine + 0.5 mg nalbuphine. Group 2: 15 mg (3 mL) of 0.5% hyperbaric bupivacaine + 1 mg nalbuphine. The primary outcome measured was the total duration of analgesia (time from injection to first rescue analgesia requirement). Secondary outcomes included two-segment regression time, motor block duration, hemodynamic changes, incidence of side effects, and Visual Analog Scale (VAS) scores at rest and during movement.

Results- Group 2 (1 mg nalbuphine) demonstrated a longer total analgesia duration (265.7 ± 30.8 min vs. 250.5 ± 32.1 min, p=0.08) and longer total motor block duration (172.8 ± 20.3 min vs. 160.4 ± 18.7 min, p=0.03) compared to Group 1. The two-segment regression time was comparable between groups (p=0.42). VAS scores at 4, 6, and 8 hours postoperatively were significantly lower in Group 2 (p<0.001), suggesting superior pain relief. The incidence of hypotension was slightly higher in Group 2 (8 vs. 3 patients, requiring vasopressors, p=NS), while nausea was reported in 7 patients in Group 2 compared to 2 in Group 1 (p=NS). No cases of pruritus, sedation, or respiratory depression were observed.

Conclusion- Intrathecal nalbuphine effectively enhances the analgesic properties of hyperbaric bupivacaine in PCNL patients. While both 0.5 mg and 1 mg doses provided prolonged analgesia, 1 mg resulted in a longer motor block and superior postoperative pain relief without significant side effects. Future studies with larger sample sizes are recommended to establish the optimal intrathecal nalbuphine dose for PCNL.