We thank Murphy et al. [1] for their interest in our study [2] and for furthering the discussion on timely assessment for prolonged motor blockade after neuraxial anaesthesia. Their concerns about the potential unintended consequence of delaying anaesthetic review from the guideline recommendation of 4–6 h are valid, and we would like to take this opportunity to clarify this matter and our stance on the issue.

We believe any abnormally prolonged motor recovery should prompt immediate review by an anaesthetist, as early intervention allows for the timely management of serious complications. However, in order to conduct the review effectively, one needs to consider what constitutes an abnormally prolonged motor block. A meta-analysis encompassing 11 randomised controlled trials involving 316 patients who received either hyperbaric (n = 6, dose range 8–12.5 mg) or isobaric (n = 5, dose range 6.6–15 mg) intrathecal bupivacaine for caesarean delivery with reported mean motor block durations ranging from 1.3 to 4.2 h [3]. In 10 of the 11 studies, the mean motor block duration was < 4 h. Similarly, Cordrey et al. showed that > 50% of patients had fully recovered motor function by 4 h, following intrathecal hyperbaric bupivacaine 0.5% or epidural lidocaine 2% with adrenaline and bicarbonate [4]. These findings align with data from the 3rd National Audit Project report [5] and McCombe and Bogod [6], which recommend that the absence of sensorimotor recovery by 4 h warrants a thorough evaluation. Based on these data, the 4-h threshold was an appropriate and logical recommendation.

After applying the 4-h threshold, we noticed frequent review triggers and found that motor block recovery often takes longer than that documented in the literature. We hypothesise this may, in part, be related to our frequent use of higher doses (13.5 mg) of intrathecal hyperbaric bupivacaine 0.75%. While this formulation is used widely in North America, we were unable to find motor block regression data specifically evaluating this formulation using the time-to-straight-leg-raise against gravity endpoint at the dose range we utilise. In the meta-analysis by Malhotra et al., aside from two trials that did not report the concentration, all others utilised bupivacaine 0.5% [3], as did the studies cited by the Association of Anaesthetists and Obstetric Anaesthetists' Association guidelines. Consequently, the data used to inform the 4-h guideline recommendation may not be generalisable to our patient population.

For patients who still have motor block after 4 h, magnetic resonance imaging is the only definitive method to determine whether the cause is a neuraxial haematoma. However, with an annual delivery volume of 7000–8000, the sheer number of investigations triggered would overwhelm both our anaesthetic and radiology departments. The regional anaesthesia alert bracelet is an excellent initiative that emphasises patient involvement and autonomy. We agree that it is an innovative and valuable patient safety measure that can supplement, but not replace, our current scheduled nurse-led hourly monitoring, which remains essential for postpartum patients who may become too distracted or fatigued to self-monitor. Furthermore, because the bracelet operates on a time-to-action trigger, setting it at 4 h would still result in a high volume of alerts, leaving our clinical dilemma unresolved.

More research is required on this subject to understand the effects of changing the timing triggers on the early detection of significant neuraxial anaesthesia complications and the use of clinical resources. We urge other centres using intrathecal hyperbaric bupivacaine 0.75% for caesarean deliveries in similar dose ranges to confirm our findings.

我们感谢 Murphy 等人 [1] 对我们的研究 [2] 的兴趣，并进一步讨论及时评估椎管内麻醉后长期运动阻滞。他们对将麻醉审查从指南建议的 4-6 小时延迟的潜在意外后果的担忧是有道理的，我们想借此机会澄清此事以及我们对该问题的立场。

我们认为，任何异常延长的运动恢复都应该立即由麻醉师进行检查，因为早期干预可以及时处理严重的并发症。然而，为了有效地进行审查，需要考虑什么构成异常延长的运动阻滞。一项荟萃分析包括 11 项随机对照试验，涉及 316 名接受高压（n = 6，剂量范围 8-12.5 mg）或等压（n = 5，剂量范围 6.6-15 mg）鞘内注射布比卡因进行剖宫产的患者，报告的平均运动阻滞持续时间为 1.3 至 4.2 小时 [3]。在 11 项研究中的 10 项研究中，平均运动阻滞持续时间为 < 4 小时。同样，Cordrey 等人表明，在鞘内注射 0.5% 高压布比卡因或 2% 硬膜外利多卡因与肾上腺素和碳酸氢盐后，> 50% 的患者在 4 小时内完全恢复了运动功能 [4]。这些发现与第 3 次国家审计项目报告 [5] 以及 McCombe 和 Bogod [6] 的数据一致，后者建议 4 小时时感觉运动没有恢复，需要进行全面评估。根据这些数据，4 h 阈值是一个适当且合乎逻辑的建议。

应用 4 小时阈值后，我们注意到频繁的审查触发器，并发现运动阻滞恢复通常需要比文献中记录的时间更长的时间。我们假设这可能部分与我们经常使用更高剂量 （13.5 mg） 的鞘内高压布比卡因 0.75% 有关。虽然这种制剂在北美广泛使用，但我们无法找到专门使用我们使用的剂量范围内对抗重力伸直腿抬高终点来评估该制剂的运动阻滞回归数据。在 Malhotra 等人的荟萃分析中，除了两项未报告浓度的试验外，所有其他试验都使用 0.5% 的布比卡因 [3]，麻醉师协会和产科麻醉师协会指南引用的研究也是如此。因此，用于为 4-h 指南推荐提供信息的数据可能无法推广到我们的患者群体。

对于 4 小时后仍存在运动阻滞的患者，磁共振成像是确定病因是否为椎管内血肿的唯一确定性方法。然而，由于年分娩量为 7000-8000 次，触发的大量检查将使我们的麻醉科和放射科不堪重负。区域麻醉警报手环是一项出色的举措，强调患者的参与和自主性。我们同意这是一项创新且有价值的患者安全措施，可以补充但不能取代我们目前预定的护士主导的每小时监测，这对于可能因过度分心或疲劳而无法自我监测的产后患者来说仍然是必不可少的。此外，由于手环在动作时间触发器上运行，因此将其设置为 4 小时仍会导致大量警报，使我们的临床困境尚未解决。

需要对这一主题进行更多研究，以了解改变时间触发器对重大椎管内麻醉并发症的早期检测和临床资源使用的影响。我们敦促其他使用鞘内注射 0.75% 高压布比卡因进行类似剂量范围的剖宫产的中心确认我们的发现。