Analgesic Efficacy of Nalbuphine as an Adjuvant to Ropivacaine in Erector Spinae Plane Block for Percutaneous Nephrolithotomy: A Randomized, Double-Blinded, Clinical Trial

BACKGROUND: Erector spinae plane block (ESPB) is an easy and safe method for postoperative analgesia. However its effect lasts only for several hours. This trial was to investigate the effectiveness of different doses of nalbuphine as an adjuvant to ropivacaine in ESPB for patients undergoing percutaneous nephrolithotomy (PCNL). METHODS: Patients scheduled for PCNL were randomized into three groups and received ultrasound-guided ESPB at T(10) level for postoperative analgesia. Each subject received 28 mL of 100 mg ropivacaine solution mixed with 2 mL of normal saline (Group R), 2 mL of 10 mg nalbuphine (Group RNL), or 2 mL of 20 mg nalbuphine (Group RNH). Primary outcome was the time to first opioid demand. Secondary outcomes were morphine consumption, VAS scores within 24 h postoperatively, rescue analgesic requirements, and length of hospital stay. RESULTS: The median [interquartile range, IQR] time to first opioid demand was significantly longer in group RNH (8.70 [6.90,14.85] h) than that of group R and group RNL (2.90 [2.00,6.30] h and 5.80 [2.95,7.00] h, respectively). VAS scores (either resting or active) within 24 h postoperatively were comparable between the three groups, with the most significant differences especially at 4, 6, 8 h. Morphine consumption at 24 h postoperatively was significant for R group vs RNH group (median difference, 9; 95% confidence interval [CI], 1.57 to 16.43; p = 0.02). CONCLUSIONS: Adding 20mg nalbuphine to ropivacaine in ESPB could significantly improve the effect of analgesia and prolong the duration of nerve blocks for PCNL.