Novel Analgesic Adjuncts for Brachial Plexus Block: A Systematic Review

This is the authors' abstract. We don't add key points for this paper.

This article reviews current evidence for the efficacy of adding novel analgesic adjuncts to brachial plexus block, the goal of which is to prolong analgesic effect without the disadvantage of systemic side effects or prolonged motor block. It may also allow for a reduction in the total dose of local anesthetic used. Novel adjuncts studied to date include opioids, clonidine, neostigmine, and tramadol. Twenty-four studies were reviewed and assessed by using specific inclusion criteria, and only those studies satisfying these criteria were included in the final assessment. Satisfactory studies were then assessed for inclusion of a systemic control group to determine peripheral effect, as opposed to possible systemic effect, of an adjunct administered peripherally. Evidence regarding the analgesic benefit of opioid adjuncts remains equivocal and more evidence is required before their routine use can be recommended. Clonidine appears to have significant analgesic benefit and to cause minimal adverse effects when used in doses up to 150 μg. Data regarding other drugs, such as tramadol and neostigmine, are not sufficient to allow for any recommendations, and further studies are required. Implications This systematic review indicates that there is little evidence for the analgesic benefit of adding opioids to brachial plexus block. Clonidine appears to be beneficial in doses up to 150 μg. There are currently insufficient data with regard to neostigmine and tramadol to allow for further recommendations.

Supports clonidine (≤150 μg) as brachial plexus block adjunct; extends perineural adjunct evidence while leaving opioids, neostigmine, and tramadol inconclusive.