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Investigating the Efficacy of Dexmedetomidine as an Adjuvant to Local Anesthesia in Brachial Plexus Block: A Systematic Review and Meta-Analysis of 18 Randomized Controlled Trials

Hussain, Nasir MSc; Grzywacz, Vincent Paul BS; Ferreri, Charles Andrew; Atrey, Amit MD, MSc, FRCS; Banfield, Laura MLIS; Shaparin, Naum MD; Vydyanathan, Amaresh MD

Regional Anesthesia & Pain Medicine: March/April 2017 - Volume 42 - Issue 2 - p 184–196
doi: 10.1097/AAP.0000000000000564
Regional Anesthesia and Acute Pain: Review Article

Background and Objectives: Dexmedetomidine has been thought to be an effective adjuvant to local anesthetics in brachial plexus blockade. We sought to clarify the uncertainty that still exists as to its true efficacy.

Methods: A meta-analysis of randomized controlled trials was conducted to assess the ability of dexmedetomidine to prolong the duration and hasten the onset of motor and sensory blockade when used as an adjuvant to local anesthesia for brachial plexus blockade versus using local anesthesia alone (control). A search strategy was created to identify eligible articles in MEDLINE, EMBASE, and The Cochrane Library. The methodological quality for each included study was evaluated using the Cochrane Tool for Risk of Bias.

Results: Eighteen randomized controlled trials were included in this meta-analysis (n = 1092 patients). The addition of dexmedetomidine significantly reduced sensory block time onset time by 3.19 minutes (95% confidence interval [CI], −4.60 to −1.78 minutes; I2 = 95%; P < 0.00001), prolonged sensory block duration by 261.41 minutes (95% CI, 145.20–377.61 minutes; I2 = 100%; P < 0.0001), reduced the onset of motor blockade by 2.92 minutes (95% CI, −4.37 to −1.46 minutes; I2 = 96%, P < 0.0001), and prolonged motor block duration by 200.90 minutes (CI, 99.24–302.56 minutes; I2 = 99%; P = 0.0001) as compared with control. Dexmedetomidine also significantly prolonged the duration of analgesia by 289.31 minutes (95% CI, 185.97–392.64 minutes; I2 = 99%; P < 0.00001). Significantly more patients experienced intraoperative bradycardia with dexmedetomidine (risk difference [RD], 0.06; 95% CI, 0.00–0.11; I2 = 72%; P = 0.03); however, there was no difference in the incidence of intraoperative hypotension (RD, 0.01; 95% CI, −0.02 to 0.04; I2 = 3%; P = 0.45). It is important to note that all studies reported that intraoperative bradycardia was either transient in nature or reversible, when needed, with the administration of intravenous atropine.

Conclusions: Dexmedetomidine has the ability to hasten the onset and prolong the duration of blockade when used as an adjuvant to local anesthesia for brachial plexus blockade. Considering an analgesic effect to be either decreased pain, a longer duration of analgesic block, or decreased opioid consumption, the addition of dexmedetomidine to local anesthetics for brachial plexus blockade was found to significantly improve analgesia in all 18 included studies. However, patients receiving dexmedetomidine should be continuously monitored for the potentially harmful but reversible adverse effect of intraoperative bradycardia.

Level of Evidence: Therapeutic, level I.

From the *Central Michigan University College of Medicine, Mt Pleasant; and †University of Michigan College of Literature, Sciences, and the Arts, Ann Arbor, MI; ‡Department of Orthopaedics, St Michael's Hospital, Toronto; and §Health Sciences Library, McMaster University, Hamilton, Ontario, Canada; and ∥Department of Anesthesia, Montefiore Medical Center, Bronx, NY.

Accepted for publication November 21, 2016.

Address correspondence to: Nasir Hussain, MD (Cand), MSc, Central Michigan University College of Medicine, CMED Bldg, 1280S E Campus St, Mt Pleasant, MI 48859 (e-mail: nasir.hussain@cmich.edu).

The authors declare no conflict of interest.

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Copyright © 2017 by American Society of Regional Anesthesia and Pain Medicine.