Dexmedetomidine as an Adjuvant to Local Anesthetics in Transversus Abdominis Plane Block: A Systematic Review and Meta-analysis.

Objectives: The objective of this meta-analysis was to evaluate the analgesic effects of dexmedetomidine (DEX) in transversus abdominis plane (TAP) blocks for abdominal surgery. Methods: Electronic databases, including PubMed, EMBASE, Chinese National Knowledge Infrastructure (CNKI), Wan Fang, and the Cochrane Library, were conducted to collect the randomized controlled trials (RCTs) from inception to March 2018. RCTs investigating the impact of adding DEX to local anesthetics for TAP blocks were included in this analysis. Pain scores (at rest and movement), opioid consumption, the duration of the TAP block and the common adverse effects were analyzed. Results: Twenty published trials including 1212 patients met the inclusion criteria. The addition of DEX significantly reduced pain scores 8 hours postoperatively at rest (WMD, -0.78; 95% CI, -1.27 to -0.30; P=0.001), 4 hours postoperatively on movement (WMD, 1.13; 95% CI, -1.65 to -0.60; P < 0.001), and opioid consumption (WMD, 13.71; 95% CI, -17.83 to -9.60; P < 0.001) when compared with control group. Furthermore, perineural DEX significantly prolonged the duration of the TAP block (WMD, -3.33; 95% CI, -2.85 to -3.82; P < 0.001). It did not affect the incidence of postoperative nausea and vomiting, hypotension, bradycardia, somnolence, or pruritus. Conclusions: DEX is a potential anesthetic adjuvant that can facilitate better postoperative analgesia, reduce postoperative analgesic requirements, and prolong the local anesthetic effect when administered in TAP blocks.