Clinical analgesic efficacy of dexamethasone as a local anesthetic adjuvant for transversus abdominis plane (TAP) block: A meta-analysis

Background: Perineural dexamethasone has been shown to prolong the duration of local anesthetic (LA) effect in regional anesthesia; however, the use of perineural dexamethasone as an adjuvant to to the transversus abdominis plane (TAP) block remains controversial. This meta-analysis sought to assess the efficacy of dexamethasone in prolonging the TAP block and enhancing recovery after abdominal surgery. Methods: We identified and analyzed 9 RCTs published on or before September 30, 2017, regardless of the original language, after searching the following 6 bibliographic databases: PubMed, EMBASE, Medline, Springer, Ovid, and the Cochrane Library. databases. These studies compared the effects of perineural dexamethasone mixed with local anesthetic versus local anesthetic alone in the TAP block. The Cochrane Collaboration’s Risk of Bias Tool was used to evaluate the methodological quality of each RCT. The primary outcomes were the time until the first request for postoperative analgesics and the analog pain scores at 2, 6, 12, and 24 h after surgery. The secondary outcomes were the analgesic consumption and the incidence of nausea and vomiting on the first day after surgery. We used Trial Sequential Analysis (TSA) to control for random errors. Results: Perineural dexamethasone prolonged the duration of LA effect in the TAP block [mean difference (MD): 2.98 h; 95% confidence interval (CI): 2.19 to 3.78] and reduced analog pain scores at 2 h [MD: -1.15; 95% CI: -2.14 to -0.16], 6 h [MD: -0.97; 95% CI: -1.51 to -0.44], and 12 h [MD: -0.93; 95% CI: -1.14 to -0.72] postoperatively. Furthermore, the use of perineural dexamethasone was associated with less analgesic consumption [standard mean difference: -1.29; 95% CI: -1.88 to -0.70] and a lower incidence of nausea and vomiting [odds ratio: 0.28; 95% CI: 0.16 to 0.49] on the first day after surgery. Conclusion: Dexamethasone prolongs the LA effect when used as an adjuvant in the TAP block and improves the analgesic effects of the block.