Department of Anaesthesia, Guy's and St Thomas' NHS Foundation Trust, London, UK.
King's College London, London, UK.
Anaesthesia. 2021 Jan;76 Suppl 1:100-109. doi: 10.1111/anae.15245.
Moderate-to-severe postoperative pain persists for longer than the duration of single-shot peripheral nerve blocks and hence continues to be a problem even with the routine use of regional anaesthesia techniques. The administration of local anaesthetic adjuncts, defined as the concomitant intravenous or perineural injection of one or more pharmacological agents, is an attractive and technically simple strategy to potentially extend the benefits of peripheral nerve blockade beyond the conventional maximum of 8-14 hours. Historical local anaesthetic adjuncts include perineural adrenaline that has been demonstrated to increase the mean duration of analgesia by as little as just over 1 hour. Of the novel local anaesthetic adjuncts, dexmedetomidine and dexamethasone have best demonstrated the capacity to considerably improve the duration of blocks. Perineural dexmedetomidine and dexamethasone increase the mean duration of analgesia by up to 6 hour and 8 hour, respectively, when combined with long-acting local anaesthetics. The evidence for the safety of these local anaesthetic adjuncts continues to accumulate, although the findings of a neurotoxic effect with perineural dexmedetomidine during in-vitro studies are conflicting. Neither perineural dexmedetomidine nor dexamethasone fulfils all the criteria of the ideal local anaesthetic adjunct. Dexmedetomidine is limited by side-effects such as bradycardia, hypotension and sedation, and dexamethasone slightly increases glycaemia. In view of the concerns related to localised nerve and muscle injury and the lack of consistent evidence for the superiority of the perineural vs. systemic route of administration, we recommend the off-label use of systemic dexamethasone as a local anaesthetic adjunct in a dose of 0.1-0.2 mg.kg for all patients undergoing surgery associated with significant postoperative pain.
中重度术后疼痛持续时间长于单次外周神经阻滞的持续时间，因此，即使常规使用区域麻醉技术，仍会持续存在问题。局部麻醉辅助剂的给予，定义为同时静脉内或神经周围注射一种或多种药理学药物，是一种有吸引力且技术简单的策略，可以潜在地将外周神经阻滞的益处延长超过传统的 8-14 小时。历史上的局部麻醉辅助剂包括局部麻醉肾上腺素，其已被证明可以使镇痛平均持续时间仅延长 1 小时以上。在新型局部麻醉辅助剂中，右美托咪定和地塞米松已被证明最有能力显著延长阻滞时间。当与长效局部麻醉剂联合使用时，局部麻醉肾上腺素和地塞米松分别使镇痛的平均持续时间延长多达 6 小时和 8 小时。这些局部麻醉辅助剂安全性的证据不断增加，尽管在体外研究中发现局部麻醉肾上腺素具有神经毒性作用的结果存在矛盾。局部麻醉肾上腺素和地塞米松均不符合理想局部麻醉辅助剂的所有标准。局部麻醉肾上腺素受副作用（如心动过缓、低血压和镇静）的限制，地塞米松会稍微增加血糖。鉴于与局部神经和肌肉损伤相关的担忧以及局部神经与全身给药途径的优越性缺乏一致证据，我们建议在所有接受与明显术后疼痛相关的手术的患者中，将全身地塞米松作为局部麻醉辅助剂以 0.1-0.2mg.kg 的剂量标签外使用。
