We read with great interest the guidelines for the prevention and management of intra-operative pain during caesarean section [1]. Among the authors' recommendations are that light touch be used as the primary testing modality, aiming for a sensory block to T5 or higher. This recommendation is welcome given, as the authors point out, the “lack of consensus on what to test, how to test and what constitutes an adequate block.”

A discussion of assessment of neuraxial block, we believe, cannot occur without a discussion of local anaesthetic dosing for neuraxial anaesthesia. The dose of local anaesthetic injected is a key determinant of block height [2]. In our own institution, and many others where we have worked, anaesthetists typically administer the doses of hyperbaric bupivacaine equivalent to, or slightly above, the ED₉₅ of the drug. This is based on the findings that this will be effective in 95% of the population [3]. We believe it is important to point out that studies determining the ED₉₅ of local anaesthetic doses for spinal anaesthesia for caesarean section have typically not used light touch as a determinant for block efficacy, but rather sharp pinprick [4]. In fact, these authors could not identify any dosing studies using light touch as a primary testing modality. This is important as loss of sharp pinprick sensation is typically observed several dermatomes higher than loss of light touch [5].

Many anaesthetists, including ourselves, who are using loss of sensation to cold or pinprick as the primary testing modality will likely change to use of light touch following publication of these guidelines. We wonder whether we should be increasing the dose of local anaesthetic administered in our spinal anaesthetics? Perhaps we should be performing more combined spinal–epidurals to allow epidural top-up in cases of low sensory block? Or perhaps we should be adjusting other factors which influence block height and quality, such as patient position or dose of intrathecal opioid [2]?

The guidelines [1] are a significant step towards improved prevention and management of intra-operative pain during caesarean section under neuraxial anaesthesia. However, until such time when we have dosing studies using light touch as a primary testing modality, we believe anaesthetists switching to light touch should be cautious of the possible need to adjust their anaesthetic technique.

我们怀着极大的兴趣阅读了剖宫产术中疼痛的预防和管理指南 [ 1 ]。作者的建议之一是轻触作为主要测试方式，目标是 T5 或更高的感觉阻滞。正如作者所指出的那样，该建议是受欢迎的，因为“在测试什么、如何测试以及什么构成足够的块方面缺乏共识”。

我们认为，如果不讨论椎管内麻醉的局麻药剂量，就无法讨论椎管内阻滞的评估。注射局麻药的剂量是决定阻滞高度的关键因素 [ 2 ]。在我们自己的机构以及我们工作过的许多其他机构中，麻醉师通常使用相当于或略高于药物 ED ₉₅的高压布比卡因剂量。这是基于这样的调查结果，即这将在 95% 的人群中有效 [ 3 ]。我们认为重要的是要指出确定 ED _95的研究剖宫产脊髓麻醉的局部麻醉剂量通常不使用轻触作为阻滞效果的决定因素，而是使用尖锐的针刺 [ 4 ]。事实上，这些作者无法确定任何使用轻触作为主要测试方式的剂量研究。这很重要，因为通常观察到比失去轻触感更高的几个皮节会失去尖锐的针刺感 [ 5 ]。

许多麻醉师，包括我们自己，在这些指南发布后，使用对寒冷或针刺的感觉丧失作为主要测试方式，可能会改为使用轻触。我们想知道是否应该增加在我们的脊髓麻醉剂中施用的局部麻醉剂的剂量？也许我们应该进行更多的联合脊髓硬膜外麻醉，以便在低感觉阻滞的情况下进行硬膜外麻醉？或者也许我们应该调整影响块高度和质量的其他因素，例如患者位置或鞘内阿片类药物的剂量 [ 2 ]？

该指南 [ 1 ] 是朝着改善椎管内麻醉下剖腹产术中疼痛预防和管理迈出的重要一步。然而，在我们使用轻触作为主要测试方式进行剂量研究之前，我们认为转为轻触的麻醉师应该小心调整其麻醉技术的可能需要。