Comparison of Analgesic Efficacy of Laparoscope-Assisted and Ultrasound-Guided Transversus Abdominis Plane Block after Laparoscopic Colorectal Operation: A Randomized, Single-Blind, Non-Inferiority Trial

BACKGROUND: Transversus abdominis plane (TAP) block has been used as a component of multimodal analgesia after abdominal operation. We introduced a new laparoscope-assisted TAP (LTAP) block technique using intraperitoneal injection and compared its analgesic effect with that of an ultrasound-guided TAP (UTAP) block in terms of postoperative pain control. STUDY DESIGN: A prospective, randomized, single-blinded non-inferiority clinical trial was conducted with patients undergoing elective laparoscopic colectomy for colon cancer. Eighty patients were randomly assigned (1:1 ratio) to the UTAP and LTAP groups. At the end of the operation, opioid consumption and numeric rating scores (NRS; 0 [no pain] to 10 [worst pain]) of pain were recorded at 2, 6, 24, and 48 hours postoperatively and were compared between the groups. The primary end point was pain NRS during rest at 24 hours after operation. RESULTS: Thirty-eight patients in the LTAP group and 35 patients in the UTAP group completed the study protocol. We found no significant difference in mean ± SD pain NRS during rest at 24 hours between the LTAP group (3.90 ± 1.7) and the UTAP group (4.5 ± 1.9). The mean difference in pain NRS during rest at 24 hours was 0.57 (95% CI −0.26 to 1.41). Because the lower boundary of a 95% CI for the differences in pain NRS was > −1, non-inferiority was established. There was no significant difference between the groups in NRS pain during rest, NRS pain on movement, and postoperative morphine consumption during the 48 hours after operation. CONCLUSIONS: These results show our new LTAP block technique was non-inferior to the ultrasound-guided technique in providing a TAP block after laparoscopic colorectal operation.