El-Boghdadly Kariem, Brull Richard, Sehmbi Herman, Abdallah Faraj W
From the *Department of Anesthesia, University of Toronto; Toronto, Ontario, Canada; †Department of Anesthesia, Toronto Western Hospital, Toronto, Ontario, Ontario, Canada; ‡Department of Anesthesia, Women's College Hospital, Toronto, Ontario, Canada; and §Department of Anesthesia and Keenan Research Centre in the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario, Canada.
Anesth Analg. 2017 Jun;124(6):2008-2020. doi: 10.1213/ANE.0000000000002014.
Clonidine, an α-2 agonist, has long been used as a local anesthetic adjunct with proven efficacy to prolong peripheral nerve block duration. Dexmedetomidine, a newer α-2 agonist, has a more favorable pharmacodynamic and safety profile; however, data comparing its efficacy as an adjunct to that of clonidine are inconsistent. We sought to compare the clinical efficacy of these 2 α-2 agonists by examining their effects on peripheral nerve block characteristics for upper extremity surgery.
A preliminary search found that the overwhelming majority of randomized controlled trials comparing perineural dexmedetomidine to clonidine for upper extremity surgery were in the setting of supraclavicular brachial plexus block (SCB). Therefore, we performed a systematic review and meta-analysis of randomized controlled trials comparing dexmedetomidine with clonidine as perineural adjuncts to single-injection SCB. Sensory and motor block duration and onset, analgesic duration, α-2 agonist side effects, and block complications were analyzed. Sensory block duration was designated as a primary outcome. Data were combined using random-effects modeling, and ratio-of-means was used to analyze the results.
A total of 868 patients from 14 clinical studies were included in the analysis. Compared with clonidine, dexmedetomidine prolonged the duration (ratio of means [95% confidence interval {CI}]) of sensory block by an estimate of 1.2 (1.2-1.3; P< .00001). It also prolonged the duration (ratio of means [99% CI]) of motor block by an estimate of 1.2 (1.1-1.3; P < .00001), and analgesia by an estimate of 1.2 (1.1-1.3; P < .00001). It also hastened the onset of sensory block by an estimate of 0.9 (0.8-1.0; P < .00001) and motor block by an estimate of 0.9 (0.9-1.0; P = .002). Dexmedetomidine was associated with an increased odds ratio (99% CI) of transient bradycardia by an estimate of 7.4 (1.3-40.8; P = .003) and postoperative sedation by an estimate of 11.8 (1.9-73.6; P = .0005). There were no differences in other α-2 agonist-related side effects or block-related complications.
Compared with clonidine as a local anesthetic adjunct for single-injection SCB, perineural dexmedetomidine enhances sensory, motor, and analgesic block characteristics. These benefits should be weighed against the increased risk of transient bradycardia.
可乐定是一种α-2激动剂，长期以来一直用作局部麻醉辅助药物，其延长周围神经阻滞时间的疗效已得到证实。右美托咪定是一种较新的α-2激动剂，具有更有利的药效学和安全性；然而，比较其作为辅助药物与可乐定疗效的数据并不一致。我们试图通过检查它们对上肢手术周围神经阻滞特征的影响来比较这两种α-2激动剂的临床疗效。
初步检索发现，绝大多数比较神经周围注射右美托咪定与可乐定用于上肢手术的随机对照试验是在锁骨上臂丛神经阻滞（SCB）的情况下进行的。因此，我们对比较右美托咪定与可乐定作为单次注射SCB神经周围辅助药物的随机对照试验进行了系统评价和荟萃分析。分析了感觉和运动阻滞持续时间及起效时间、镇痛持续时间、α-2激动剂的副作用和阻滞并发症。感觉阻滞持续时间被指定为主要结局。使用随机效应模型合并数据，并使用均值比来分析结果。
分析纳入了来自14项临床研究的868例患者。与可乐定相比，右美托咪定使感觉阻滞持续时间（均值比[95%置信区间{CI}]）延长，估计值为1.2（1.2 - 1.3；P <.00001）。它还使运动阻滞持续时间（均值比[99%CI]）延长，估计值为1.2（1.1 - 1.3；P <.00001），镇痛持续时间延长，估计值为1.2（1.1 - 1.3；P <.00001）。它还使感觉阻滞起效时间加快，估计值为0.9（0.8 - 1.0；P <.00001），运动阻滞起效时间加快，估计值为0.9（0.9 - 1.0；P =.002）。右美托咪定与短暂性心动过缓的优势比（99%CI）增加有关，估计值为7.4（1.3 - 40.8；P =.003），与术后镇静的优势比增加有关，估计值为11.8（1.9 - 73.6；P =.0005）。在其他与α-2激动剂相关的副作用或与阻滞相关的并发症方面没有差异。
与可乐定作为单次注射SCB的局部麻醉辅助药物相比，神经周围注射右美托咪定可增强感觉、运动和镇痛阻滞特征。这些益处应与短暂性心动过缓风险增加相权衡。
