The analgesic efficacy of ultrasound-guided transversus abdominis plane block for retroperitoneoscopic renal surgery: a randomized controlled study

BACKGROUND: Ultrasound-guided lateral transversus abdominis plane (TAP) block can provide definite analgesia to the anterior abdominal wall. However, whether this method is useful in renal surgery through the lateral abdominal wall pathway remains unknown. The study aimed to evaluate the analgesic efficacy of lateral TAP block for retroperitoneoscopic partial or radical nephrectomy. METHOD: In this prospective, randomized, double-blind, placebo-controlled trial, eligible patients were randomized into two groups. After anaesthesia induction, ultrasound-guided lateral TAP block was performed with either 30 ml of 0.4% ropivacaine (Group T) or an equivalent volume of normal saline (Group C). The primary outcomes were opioid consumption during surgery and in the first 24 h after surgery. Secondary outcomes included postsurgical pain intensity immediately awakening from anaesthesia and at 0.5, 1, 2, 6, 12, and 24 h after surgery, as well as recovery variables including the incidence of postoperative nausea and vomiting (PONV), sleep quality, time to first ambulation, drainage and length of hospital stay. RESULTS: A total of 104 patients were enrolled and randomized (53 in Group T and 51 in Group C). Laparoscopic surgery was converted to open surgery in one patient of Group T; this patient was excluded from the outcome analysis. The opioid consumption during surgery (intravenous morphine equivalent dose: median 35.0 mg [interquartile range 18.0, 49.6] in Group C vs. 40.3 mg [20.9, 59.0] in Group T, P = 0.281) and in the first 24 h after surgery (10.8 mg [7.8, 21.7] in Group C vs. 13.2 mg [8.0, 26.6] in Group T, P = 0.311) did not differ significantly between groups. There were no significant differences between groups regarding the pain intensity at all time points after surgery and the recovery variables (all P > 0.05). CONCLUSIONS: Our results showed that, in patients undergoing retroperitoneoscopic renal surgery, preoperative lateral TAP did not decrease intra- and postoperative opioid consumption, nor did it relieve pain intensity or promote postoperative recovery in the first 24 h after surgery. However, the trial might be underpowered. TRIAL REGISTRATION: This study was registered on November 4, 2017, in the Chinese Clinical Trail Registry with the identification number ChiCTR-INR-17013244.