BACKGROUND Efforts to prolong interscalene block (ISB) analgesia include the use of local anaesthetic adjuvants such as dexamethasone. Previous work showing prolonged block duration suggests that both perineural and intravenous (i.v.) routes can both prolong analgesia. The superiority of either route is controversial given the design of previous studies. As perineural dexamethasone is an off-label use, anaesthesiologists should be fully informed of the clinical differences, if any, on block duration. This study was designed to test whether perineural vs i.v. dexamethasone administration are equivalent. METHODS We randomised 182 eligible patients scheduled for arthroscopic shoulder surgery to receive low-dose ISB (0.5% ropivacaine 5 ml) with perineural or i.v. dexamethasone 4 mg. Subjects, anaesthesiologists, and research personnel were blinded. All subjects also received a standardised general anaesthetic and multimodal analgesia. The primary outcome was duration of analgesia analysed as an equivalence outcome (2 h equivalency margin) using the two one-sided test (TOST) method. RESULTS For the primary outcome, duration of analgesia, and perineural and i.v. administration of dexamethasone were not equivalent. The upper and lower bounds of the 90% confidence interval were 1 h (P=0.12) and -2.5 h (P=0.01), respectively. The observed difference in mean block duration was not clinically relevant (0.75 h longer for i.v. dexamethasone). There were no other clinically significant differences between groups. CONCLUSION In the context of low-volume ISB with ropivacaine, perineural and i.v. dexamethasone were not equivalent in terms of their effects on block duration. However, there were no clinically significant differences in outcomes, and there is no advantage of perineural over intravenous dexamethasone. WWW.CLINICALTRIALS. GOV REGISTRATION NCT02322242.

中文翻译：

---

神经内或静脉地塞米松对小容量肌间沟臂丛神经阻滞作用的比较：一项随机等效试验。

背景技术延长肌间沟阻滞（ISB）镇痛的努力包括使用局部麻醉佐剂，例如地塞米松。先前的研究显示，阻滞持续时间延长，表明神经周围和静脉内（iv）途径均可延长镇痛作用。鉴于先前的研究设计，这两种方法的优越性都存在争议。由于神经周围地塞米松是标签以外的用途，因此麻醉医师应充分了解阻滞持续时间的临床差异（如果有的话）。这项研究的目的是测试神经鞘内注射与静脉内地塞米松注射是否等效。方法我们随机分配了182例接受关节镜肩部手术的合格患者，接受低剂量ISB（0.5％罗哌卡因5 ml），神经鞘内或静脉注射地塞米松4 mg。受试者，麻醉师和研究人员不知情。所有受试者还接受了标准化的全身麻醉和多峰镇痛。主要结果是使用两种单侧试验（TOST）方法将镇痛持续时间分析为等效结果（2小时等效裕度）。结果对于主要结局，镇痛持续时间，地塞米松的神经内和静脉给药均不相同。90％置信区间的上限和下限分别为1 h（P = 0.12）和-2.5 h（P = 0.01）。观察到的平均阻滞持续时间差异与临床无关（静脉使用地塞米松延长0.75小时）。两组之间没有其他临床上的显着差异。结论在使用罗哌卡因的小剂量ISB的情况下，就阻塞持续时间的影响而言，神经周围和静脉地塞米松均不等效。然而，在临床结局上没有显着差异，并且与静脉注射地塞米松相比，神经鞘内注射没有优势。网上临床试验。政府注册NCT02322242。