Dexamethasone Is Superior to Dexmedetomidine as a Perineural Adjunct for Supraclavicular Brachial Plexus Block: Systematic Review and Indirect Meta-analysis

Abstract

BACKGROUND: Both dexamethasone and dexmedetomidine are effective peripheral nerve block (PNB) perineural adjuncts that prolong block duration. However, each is associated with side effects. With paucity of head-to-head comparisons of these adjuncts, the question of the best adjunct to mix with local anesthetics (LA) for PNB is unanswered. This meta-analysis aims to inform current practice and future research by identifying the superior adjunct by comparing dexamethasone and dexmedetomidine. METHODS: Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, trials comparing the combination of perineural dexamethasone or dexmedetomidine with LA to LA alone for PNB were sought. The Cochrane Risk of Bias Tool was used to assess the methodological quality of trials, and indirect or network meta-analyses using random-effects modeling were planned. We designated duration of analgesia as a primary outcome. Secondary outcomes included sensory and motor block durations, sensory and motor block onset times, and the risks of hypotension, sedation, and neurological symptoms. RESULTS: Fifty trials were identified, including only 1 direct comparison, precluding a network meta-analysis. Indirect meta-analysis of 49 trials (3019 patients) was performed. Compared to dexmedetomidine, dexamethasone prolonged the duration of analgesia by a mean difference (95% confidence interval [CI]) of 148 minutes (37–259 minutes) (P = .003), without prolonging sensory/motor blockade. Dexmedetomidine increased rates of hypotension (risk ratio [95% CI], 6.3 [1.5–27.5]; P = .01) and sedation (risk ratio [95% CI], 15.8 [3.9–64.6]; P = .0001). Overall risk of bias was moderate, and publication bias was noted, resulting in downgrading evidence strength. CONCLUSIONS: There is low-quality evidence that both adjuncts similarly prolong sensory/motor blockade. However, dexamethasone may be a superior adjunct; it improves the duration of analgesia by a statistically significant increase, albeit clinically modest, equivalent to 2.5 hours more than dexmedetomidine, without the risks of hypotension or sedation. Future direct comparisons are encouraged.

Dose–response relationship of perineural dexamethasone for interscalene brachial plexus block: a randomised, controlled, triple‐blind trial

“…After the 2003 publication of the first clinical trial investigating the efficacy of perineural dexamethasone as an analgesic adjunct , its administration has spread widely in clinical practice. It has a favourable pharmacological profile and risk‐benefit ratio when compared with other adjuncts . Perineural dexamethasone combined with long‐acting local anaesthetic prolongs analgesia by 8 h, at the expense of a slight increase in blood glucose concentration .…”

Comparison of ultrasound guided interscalene brachial plexus block using 0.2% ropivacaine with dexmedetomidine and 0.2% ropivacaine with dexamethasone - A prospective observational study

“…Bradycardia and hypotension are one of the most common adverse effects of alpha -2 agonists. 18 We did not come across such events in our study, which is likely due to smaller doses used. Use of adjuvants in nerve blocks is a well-established practice globally.…”

Characteristics of a single- versus multiple-injection axillary brachial plexus block: a single-blinded randomised, clinical trial

“…This outcome should also be confirmed in a subsequent trial before drawing definitive conclusions. Of note, we elected not to include either intravenous or perineural dexamethasone 11,12 or dexmedetomidine 13 during this investigation despite the common use of adjuncts in our practice. The impact of injection approach on block onset, duration or analgesic requirements in the setting of adjunct use represents an unknown that may impact the generalizability of our finding to practices where these are common.…”