Peripheral nerve block and local anaesthetic dose, how much is enough?
Peripheral nerve block and local anaesthetic dose, how much is enough?
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周围神经阻滞和局麻药剂量，多少才够？
DOI：
10.1111/anae.12629
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发表时间：
2014
期刊：
影响因子：
10.7
通讯作者：
S. Szűcs
中科院分区：
文献类型：
--
作者：
B. O'donnell;S. Szűcs
“局部麻醉总是有效的——只要你把正确剂量的药物放在正确的地方”[1]。Denny和Harrop-Griffiths的这段深刻的引言揭示了区域麻醉中普遍具有吸引力的简单性。然而，他们的陈述表面上很简单，掩盖了两个相互关联的变量的真正复杂性：“正确的剂量”和“正确的位置”。上肢手术中周围神经阻滞的早期报道出现在1885年。William Stewart Halsted在直视下用可卡因浸泡锁骨上臂丛进行上肢阻滞。在这个具有里程碑意义的报告中，开放性手术解剖促进了局部麻醉剂在“正确位置”的沉积。事后看来，可卡因显然不是用于局部麻醉的“正确药物”。不考虑其精神作用和成瘾的可能性，心血管并发症限制了可卡因作为局部麻醉剂的使用。可卡因的局部麻醉作用需要相当大的剂量。即使在低剂量下也会发生中枢介导的交感神经效应（脑干外流增加，肾上腺素能受体对去甲肾上腺素的敏感性增强），因此在使用可卡因的区域麻醉期间，心血管不良反应的可能性很高。虽然霍尔斯特德可能不是第一个报告使用可卡因作为局部麻醉剂的人，但这种形式的麻醉随着用于皮下注射的空心针头的可用性而越来越受欢迎。一种由优雅的经皮神经定位技术组成的艺术形式随后发展起来，随之产生了区域麻醉的亚专科。“传统的”周围神经阻滞技术经受住了时间的考验，它涉及到将针头盲目地推进到目标神经的假定位置。针尖位置的替代标记，如远端感觉（感觉异常）或运动（肌肉抽搐）反应，用于指示针头放置在所需位置。一项被广泛引用的法令，“无感觉异常，无麻醉”[5,6]，是默认针头和神经之间需要近距离接触才能将药物“放在正确的位置”。盲神经定位技术最关键的限制是在注射局部麻醉剂之前确定针尖和目标神经之间的精确关系。大注射量（大是一个相对于目标神经表面积的术语）历来被用来克服这一限制。传统观点认为，只要给予足够大的局部麻醉，将阻滞针放置在目标神经的一般附近，就可以成功地阻断周围神经。末梢神经阻滞的局部麻醉剂量以最大允许剂量为原则。最大允许剂量可以计算并稀释成一个大的，方便给药的体积（通常为30 - 40毫升）。使用最大允许剂量的大容量周围神经阻滞可以成功达到预期的效果，但有报道称这种溶液被全身吸收和无意中血管内注射，造成严重和灾难性的后果[7-10]。最近关于神经损伤和全身毒性的大型前瞻性研究报告表明，周围神经阻滞后的不良患者结果与高剂量局部麻醉直接相关[11,12]。全身性毒性是一种剂量依赖性现象，因此限制了
“Regional anaesthesia always works —provided you put the right dose of the right drug in the right place” [1]. This insightful quote from Denny and Harrop-Griffiths reveals a universally attractive simplicity inherent in regional anaesthesia. The apparent simplicity in their statement, however, shrouds the true complexity of two interrelated variables: ‘right dose’ and ‘right place’. An early report of peripheral nerve block for upper limb surgery appeared in 1885. William Stewart Halsted performed an upper limb block by soaking the surpaclavicular brachial plexus with cocaine under direct vision [2]. In this landmark report, open surgical dissection facilitated deposition of local anaesthetic in ‘the right place’. With the advantage of hindsight, it is now evident that cocaine was very obviously not the ‘right drug’ for regional anaesthesia. Irrespective of its psychoactive effects and the potential for addiction, cardiovascular complications limit the use of cocaine as a local anaesthetic [3]. The local anaesthetic effect of cocaine requires the administration of relatively high doses. Centrally mediated sympathomimetic effects (increased brainstem outflow, with enhanced adrenergic receptor sensitivity to noradrenaline) occur even at low doses, and therefore the likelihood of adverse cardiovascular effects during regional anaesthesia using cocaine is high. Although Halsted may not have been the first to report the use of cocaine as a local anaesthetic [4], this form of anaesthesia grew in popularity in tandem with the availability of hollow-bore needles for hypodermic administration. An art form consisting of elegant, percutaneous nerve localisation techniques subsequently evolved, and with them the subspecialty of regional anaesthesia came into being. ‘Traditional’ peripheral nerve block techniques, which have stood the test of time, involve the blind advancement of needles toward the presumed location of target nerves. Surrogate markers of the needle tip’s location, such as distal sensory (paraesthesia) or motor (muscle twitch) responses, are used to indicate needle placement in the desired position. A widely quoted edict, ‘no paresthesia, no anaesthesia’ [5, 6], is tacit acknowledgement that close proximity is required between the needle and nerve to put the drug ‘in the right place’. The most critical limitation of blind nerve localisation techniques is identifying the precise relationship between the needle’s tip and target nerve immediately before the injection of local anaesthetic. Large injectate volume (large being a term relative to the surface area of the target nerve(s)) has been historically used to overcome this limitation. Conventional wisdom suggests that a block needle placed in the general vicinity of target nerves would allow successful peripheral nerve block, so long as a sufficiently large volume of local anaesthetic is administered. Local anaesthetic dosing in peripheral nerve block is based upon the principle of maximal allowable dose. A maximal allowable dose may be calculated and diluted into a large, convenient-toadminister volume (usually 30– 40 ml). Large-volume peripheral nerve block using the maximal allowable dose may achieve the desired outcome successfully, but systemic absorption and unintentional intravascular injection of such solutions have been reported, with serious and catastrophic consequences [7–10]. Recent reports of nerve injuries and systemic toxicity in large prospective registries indicate that adverse patient outcome following peripheral nerve block is directly related to high doses of local anaesthetic [11, 12]. Systemic toxicity is a dose-dependent phenomenon, therefore limiting the