Comparison of analgesic modalities for patients undergoing midline laparotomy: a systematic review and network meta-analysis

Midline laparotomy is associated with severe pain. Epidural analgesia has been the established standard, but multiple alternative regional anesthesia modalities are now available. We aimed to compare continuous and single-shot regional anesthesia techniques in this systematic review and network meta-analysis. We included randomized controlled trials on adults who were scheduled for laparotomy with solely a midline incision under general anesthesia and received neuraxial or regional anesthesia for pain. Network meta-analysis was performed with a frequentist method, and continuous and dichotomous outcomes were presented as mean differences and odds ratios, respectively, with 95% confidence intervals. The quality of evidence was rated with the  grading of recommendations, assessment, development, and evaluation system. Overall, 36 trials with 2,056 patients were included. None of the trials assessed erector spinae plane or quadratus lumborum block, and rectus sheath blocks and transversus abdominis plane blocks were combined into abdominal wall blocks (AWB). For the co-primary outcome of pain score at rest at 24 hr, with a minimal clinically important difference (MCID) of 1, epidural was clinically superior to control and single-shot AWB; epidural was statistically but not clinically superior to continuous wound infiltration (WI); and no statistical or clinical difference was found between control and single-shot AWB. For the co-primary outcome of cumulative morphine consumption at 24 hr, with a MCID of 10 mg, epidural and continuous AWB were clinically superior to control; epidural was clinically superior to continuous WI, single-shot AWB, single-shot WI, and spinal; and continuous AWB was clinically superior to single-shot AWB. The quality of evidence was low in view of serious limitations and imprecision. Other results of importance included: single-shot AWB did not provide clinically relevant analgesic benefit beyond two hr; continuous WI was clinically superior to single-shot WI by 8–12 hr; and clinical equivalence was found between epidural, continuous AWB, and continuous WI for the pain score at rest, and epidural and continuous WI for the cumulative morphine consumption at 48 hr. Single-shot AWB were only clinically effective for analgesia in the early postoperative period. Continuous regional anesthesia modalities increased the duration of analgesia relative to their single-shot counterparts. Epidural analgesia remained clinically superior to alternative continuous regional anesthesia techniques for the first 24 hr, but reached equivalence, at least with respect to static pain, with continuous AWB and WI by 48 hr. Trial registration: PROSPERO (CRD42021238916); registered 25 February 2021.