Christopher Noss, Lindsay MacKenzie and Mark Kostash
The benefit of adjuvant dexamethasone in regional anesthesia has recently been the focus of investigation as clinical reports suggest improved block characteristics. However, its use remains off label and few large randomized controlled trials have been completed. A systematic review was undertaken to highlight current research efforts and findings in this area. The authors searched for randomized clinical trials evaluating dexamethasone as admixture in brachial plexus nerve blocks. Eleven trials involving brachial plexus block met inclusion criteria (953 patients, 456 received dexamethasone). Local anesthetic agents studied included lidocaine, mepivacaine, bupivacaine and ropivacaine. Dosing ranged from 4 to 10 mg with the majority of trials using 8 mg (9 trials). Permanent nerve injury or serious complications were not reported in any trial. Trials consistently demonstrated significant prolongation of analgesia (1.5 to 4.0 times) regardless of which local anesthetic was utilized. The effect of dexamethasone on block onset was variable and its clinical benefit unclear. Dexamethasone consistently reduced postoperative pain scores and early opioid consumption (≤ 48 hours), but did not impact total opiate consumption. The most recent evidence raises the possibility of a systemic mechanism of action, potentially eliminating the need for perineural administration. In conclusion, adjuvant dexamethasone significantly prolongs the duration of analgesia when used in brachial plexus nerve blockade and has not been associated with any adverse complications to date. Large clinical trials with particular focus on systemic versus perineural administration are required to better evaluate the clinical use and safety profile of this promising adjuvant in regional anesthesia.