Margiotta and Plaat offer an argued rationale on how general anaesthesia should be conducted for the obstetric patient who has bled extensively, suggesting that high-dose opioids may be in regular use and arguing that lower doses should be used [1]. Regarding NAP7, which the authors refer to, we offer some clarification.

In NAP7, of the 28 cases of obstetric peri-operative cardiac arrest [2], six involved both a general anaesthetic and obstetric haemorrhage. In two cases the haemorrhage occurred at some time after, and distant to, induction of general anaesthesia so these are not germane to the discussion. Of the four relevant cases, at induction, none received fentanyl: two received alfentanil and two no opioid. None received any other opioids before cardiac arrest. All four patients did receive vasopressors before cardiac arrest.

Regarding anaesthesia as a cause of cardiac arrest, as we explained in a recent letter [3] this is not equivalent to being an indication of iatrogenic harm. As an example, in the case of anaphylaxis, the causal factors are the patient (due to their allergy) and anaesthesia (as anaphylaxis would not occur without drug administration). It is no surprise that in obstetric anaesthesia, dealing with generally young and healthy patients, the patient is an infrequent cause of cardiac arrest. Further, as many obstetric anaesthetic interventions (e.g. neuraxial analgesia) involve no surgery at all, it is inevitable that in peri-operative obstetric cardiac arrest, anaesthesia will be a relatively more prominent cause than surgery. Thus, the observation that 68% of NAP7 obstetric cases have anaesthesia as a key cause is, in large part, a consequence of the nature of the service, rather than any indication of poor quality anaesthesia care. We separately assessed the quality of care (before, during, after cardiac arrest, and overall): obstetric anaesthesia had among the lowest ratings of poor care of all specialities in NAP7. Specifically considering the four cases cited above, none were judged to involve poor quality care by the assessing panel.

We note that the DREAMY study, the most recent large-scale service evaluation of UK obstetric general anaesthesia, reported that 57% of surgical obstetric cases received no opioids at induction, including 64% of caesarean sections [4]. It is likely that few obstetric cases are performed as a ‘cardiac anaesthetic’, particularly as NAP7 identified that most emergency obstetric anaesthesia is delivered by resident doctors.

As there were only four cases of obstetric haemorrhage and cardiac arrest in NAP7, the project can add little robust data to the debate. Certainly, although we did not collect drug doses, there was no evidence of widespread excessive opioid use at induction or of a classic ‘cardiac style’ induction. The NAP7 report does discuss the potential for induction drugs to cause haemodynamic compromise in a hypovolaemic obstetric patient and whether alternatives, such as ketamine, may be preferable [5]. Similarly, too high doses of induction drugs, such as thiopental and propofol, administered to patients in shock, were identified as a contributing factor to poor outcomes in the 2014 MBRRACE Report [6].

No doubt the discussion regarding general anaesthesia and the bleeding obstetric patient will continue. We hope this letter clarifies the relatively sparse data available from NAP7.

Margiotta 和 Plaat 就如何对大量出血的产科患者进行全身麻醉提出了有争议的理由，认为可以经常使用大剂量阿片类药物，并认为应该使用较低剂量的阿片类药物 [1]。关于作者提到的 NAP7，我们提供了一些澄清。

在 NAP7 中，在 28 例产科围手术期心脏骤停病例中 [2]，6 例同时涉及全身麻醉和产科出血。在 2 例病例中，出血发生在全身麻醉诱导之后的某个时间，并且距离全身麻醉很远，因此这些与讨论无关。在四例相关病例中，在诱导时，没有人接受芬太尼治疗：2 例接受阿芬太尼治疗，2 例没有接受阿片类药物治疗。没有人在心脏骤停前接受任何其他阿片类药物。所有 4 例患者在心脏骤停前均接受了血管加压药治疗。

正如我们在最近的一封信中解释的那样 [3] 将麻醉视为心脏骤停的原因，这并不等同于医源性伤害的迹象。例如，在过敏反应的情况下，致病因素是患者（由于过敏）和麻醉（因为如果不给药，过敏反应就不会发生）。毫不奇怪，在产科麻醉中，处理通常是年轻和健康的患者，患者是心脏骤停的罕见原因。此外，由于许多产科麻醉干预（例如 椎管内镇痛）根本不涉及手术，因此在围手术期产科心脏骤停中，麻醉不可避免地会是比手术更突出的原因。因此，观察到 68% 的 NAP7 产科病例将麻醉作为关键原因，这在很大程度上是服务性质的结果，而不是麻醉护理质量差的任何迹象。我们分别评估了护理质量（心脏骤停前、期间、心脏骤停后和总体）：产科麻醉在 NAP7 的所有专业中护理质量最低。具体考虑到上述 4 个案例，评估小组没有一个案例被判定为护理质量差。

我们注意到，DREAMY 研究是英国产科全身麻醉的最新大规模服务评估，报告称 57% 的外科产科病例在引产时未接受阿片类药物，包括 64% 的剖宫产 [4]。可能很少有产科病例作为“心脏麻醉剂”进行，特别是因为 NAP7 确定大多数紧急产科麻醉是由住院医生提供的。

由于 NAP7 中只有 4 例产科出血和心脏骤停，因此该项目无法为争论提供多少可靠的数据。当然，虽然我们没有收集药物剂量，但没有证据表明在诱导时广泛过度使用阿片类药物或经典的“心脏式”诱导。NAP7 报告确实讨论了诱导药物可能导致低血容量产科患者血流动力学受损的可能性，以及氯胺酮等替代药物是否更可取 [5]。同样，2014 年 MBRRACE 报告指出，对休克患者给予过高剂量的诱导药物（如硫喷妥钠和异丙酚）是导致不良结局的一个因素 [6]。

毫无疑问，关于全身麻醉和出血产科患者的讨论将继续进行。我们希望这封信能澄清 NAP7 提供的相对稀疏的数据。