Effects of dexamethasone as a local anaesthetic adjuvant for brachial plexus block: a systematic review and meta-analysis of randomized trials

Abstract

Background: Brachial plexus nerve blocks (BPBs) have analgesic and opioid sparing benefits for upper extremity surgery. Single-injection techniques are limited by the pharmacological duration and therapeutic index of local anaesthetics (LAs). Continuous catheter techniques, while effective can present management challenges. Off-label use of perineural dexamethasone as an LA adjuvant has been utilized to prolong single-injection techniques. The objectives of this systematic review and meta-analysis are to assess the contemporary literature and quantify the effects of dexamethasone on BPB.

Methods: The authors searched for randomized, placebo-controlled trials that compared BPB performed with LA alone with that performed with LA and perineural dexamethasone. Meta-analysis was performed using a random effects model with subgroup analysis stratified by LA (long vs intermediate). The primary outcome was duration of sensory block or analgesia; the secondary outcomes were motor block duration, opioid consumption, and BPB complications.

Results: Nine trials (801 patients) were included with 393 patients receiving dexamethasone (4-10 mg). Dexamethasone prolonged the analgesic duration for long-acting LA from 730 to 1306 min [mean difference 576 min, 95% confidence interval (CI) 522-631] and for intermediate from 168 to 343 min (mean 175, 95% CI 73-277). Motor block was prolonged from 664 to 1102 min (mean 438, 95% CI 89-787). The most recent trial demonstrated equivalent prolongation with perineural or systemic administration of dexamethasone compared with placebo.

Conclusions: Perineural administration of dexamethasone with LA prolongs BPB effects with no observed adverse events. The effects of systemic administration of dexamethasone on BPB must be investigated.

Keywords: anaesthesia adjuvants; dexamethasone; nerve block.