Effects of dexmedetomidine as a local anesthetic adjuvant for brachial plexus block : a systematic review and meta-analysis

Background: Brachial plexus blocks (BPBs) improve postoperative analgesia, and reduce rescue analgesic consumption for upper limb surgeries. However, their benefits may be short lived. This meta-analysis was performed to examine whether perineural dexmedetomidine (DEX) combined with local anesthetics (LAs) for BPB can prolong the duration of analgesia compared with LA alone. Methods: All randomized controlled trials (RCTs) testing the impact of adding DEX to LAs for single-injection BPBs in adults undergoing upper limb surgery without general anesthesia were searched. The primary outcome was duration of analgesia, sensory block duration, motor block duration, and side effects; the secondary outcomes were block onset times, analgesic consumption, and hemodynamic parameters. Results: Thirteen trials (818 patients, 369 received DEX) were included. Dexmedetomidine prolonged the duration of analgesia by 285.02 min [95% confidence interval (CI): 181.55, 388.49, P<0.00001]. Motor block duration was prolonged by 250.63 min [95% CI: 148.10, 353.17, P<0.00001]. Sensory block duration was prolonged by 266.45 min [95% CI: 148.29, 384.61, P<0.00001]. DEX increased the risk of bradycardia [odds ratio 15.75; 95% CI: 4.02, 61.78, P<0.0001]. Conclusions: Perineural DEX combined with LAs prolong the duration of analgesia, however, the risk of bradycardia was increased at the same time.