Efficacy and safety of buprenorphine in peripheral nerve blocks A meta-analysis of randomised controlled trials

BACKGROUND The duration of analgesia provided by nerve blocks is limited if local anaesthetics are administered alone. Therefore, a variety of additives to local anaesthetics have been investigated to prolong postoperative analgesia following single-shot nerve blocks. OBJECTIVE(S) The aims of the current meta-analysis were to assess the efficacy and safety of the addition of perineural buprenorphine to local anaesthetic compared with local anaesthetic alone, or combined with systemic administration of buprenorphine, or other perineural opioids for peripheral nerve blocks. DESIGN Systematic review and meta-analysis of randomised controlled trials (RCTs). DATA SOURCES The following data sources were systematically searched: MEDLINE, CENTRAL and EMBASE (till 03/2016). ELIGIBILITY CRITERIA All RCTs focusing on the efficacy and safety of perineural buprenorphine combined with local anaesthetic compared with local anaesthetic alone, or in combination with systemic buprenorphine, or other perineural opioids for peripheral nerve blocks were included. RESULTS We included 13 RCTs (685 patients). Participants treated with perineural buprenorphine combined with local anaesthetic showed a longer duration of analgesia compared with those receiving local anaesthetic alone [ mean difference 8.64 h, 95% confidence interval (CI) (6.44 to 10.85); P < 0.01]. However, the buprenorphine group had a significantly higher relative risk (RR) for postoperative nausea and vomiting (PONV) [RR 5.0, 95% CI (1.12 to 22.27); P = 0.03]. The perineural administration of buprenorphine provided a longer duration of analgesia than an intramuscular application [mean difference 6.87 h, 95% CI (4.02 to 9.71); P < 0.01] without evidence of a difference in the incidence of PONV between the modes of administration [RR 0.76, 95% CI (0.28 to 2.03); P = 0.58]. CONCLUSION This meta-analysis revealed that the addition of buprenorphine to a local anaesthetic peripheral nerve block prolongs postoperative analgesia for about 8 h but significantly increases the risk for PONV. Perineural administration is more effective than systemic application but is associated with a similar risk of PONV. However, these results were influenced by heterogeneity so that further trials (especially head-to-head comparisons) are needed in the future.