REctus Sheath block for postoperative analgesia in gynecological ONcology Surgery (RESONS): a randomized-controlled trial.

Background: Opioid-sparing pain management is important for Enhanced Recovery After Surgery. Rectus sheath (RS) blocks are emerging as a promising modality for pain relief following midline laparotomy; however, there are limited prospective clinical trials testing their efficacy. The purpose of this randomized-controlled trial is to assess the morphine-sparing effect of local anesthetic (LA) boluses through RS catheters following elective gynecological oncology surgery.

Method: After patients' informed consent, bilateral RS catheters were placed intraoperatively in 74 females (American Society of Anesthesiologists physical status I-II) undergoing elective midline laparotomy under general anesthesia. The patients were randomized to receive 20-mL injections of either LA (0.25% bupivacaine) or normal saline (NS) postoperatively every six hours for 48 hr. Groups were compared for the co-primary outcomes of 24- and 48-hr morphine requirements. The secondary outcomes were numeric rating scale (NRS) scores for pain recorded at rest and with movement.

Results: The mean (SD) morphine consumption was significantly reduced in the LA group compared with the NS group at 24 hr [8.8 (8.3) mg vs 27.3 (10.0) mg, respectively; mean difference, 18.5 mg; 95% confidence interval (CI), 14.3 to 22.8; P < 0.001] and at 48 hr [14.8 (11.0) mg vs 42.4 (16.8) mg, respectively; mean difference, 27.7 mg; 95% CI, 20.9 to 34.3; P < 0.001]. At 48 hr postoperatively, there was also a significant decrease in the median [interquartile range] NRS scores for pain in the LA group compared with the NS group, both at rest (3 [2-3] vs 5 [5-6], respectively; P < 0.001) and with movement (4 [4-5] vs 7 [6-8], respectively; P < 0.001).

Conclusion: The use of intermittent LA boluses through RS catheters is an effective morphine-sparing pain management strategy for females undergoing midline laparotomy for gynecological cancer surgery. This study was registered with the Clinical Trial Registry of India (CTRI/2013/10/004075).