The 7th National Audit Project (NAP7) confirmed haemorrhage as a leading cause of maternal cardiac arrest[1]. In this audit of cardiac arrest in patients under the care of an anaesthetist, nearly half of the obstetric cases involved a general anaesthetic, and anaesthetic care was judged to be a key factor in 68% of cases. The specific drugs used for induction of anaesthesia were not recorded [1]. We speculate that over-generous use of opioids may be implicated. In the hypovolaemic obstetric patient, it is important to minimise the haemodynamic effects of induction. Most anaesthetists are familiar with techniques that achieve smooth induction for patients with cardiac disease. During and after training, anaesthetists come across more opportunities to care for such patients compared with managing major trauma. This may explain why, anecdotally at least, they tend to opt for a ‘cardiac anaesthetic induction’ comprising high-dose opioids with a reduced dose of induction drug when providing anaesthesia to patients who are haemodynamically unstable [2].

Liberal use of opioids in a hypovolaemic patient may, however, worsen haemodynamic status. Due to a reduced volume of distribution and clearance, plasma concentrations of fentanyl during haemorrhage can double. Activation of the sympathetic nervous system maintains cardiac output in the face of hypovolaemia through an increase in heart rate and systemic vascular resistance [3]. Fentanyl, through its sympatholytic action, can obtund these mechanisms, exacerbating haemodynamic instability, especially at high doses. It is for this reason that rapid sequence induction in a patient with shock is undertaken using limited doses of opioids, e.g. 1 μg.kg^-1 of fentanyl [4]. Once effective volume resuscitation has been established and blood pressure has increased, fentanyl can be titrated in aliquots to dilate the microcirculation and restore tissue perfusion, as evidenced by a reduction in serum lactate and base deficit [5].

To promote haemodynamic stability, we suggest that the anaesthetic management of an obstetric patient with haemorrhage should be more akin to that of a patient with trauma and shock by judicious use of opioids and induction with drugs such as ketamine. A ‘cardiac anaesthetic’ should instead be reserved for those with cardiac pathology.

第七次国家审计项目（NAP7）确认出血是孕产妇心脏骤停的主要原因[ 1 ]。在对麻醉师护理下的患者心脏骤停的审计中，近一半的产科病例涉及全身麻醉，麻醉护理被认为是 68% 病例的关键因素。没有记录用于麻醉诱导的具体药物[ 1 ]。我们推测可能与过度大量使用阿片类药物有关。对于低血容量产科患者，重要的是尽量减少引产对血流动力学的影响。大多数麻醉师都熟悉为心脏病患者实现顺利诱导的技术。在培训期间和培训后，与处理重大创伤相比，麻醉师有更多机会护理此类患者。这至少可以解释为什么在为血流动力学不稳定的患者提供麻醉时，他们倾向于选择“心脏麻醉诱导”，其中包括高剂量阿片类药物和减少剂量的诱导药物[ 2 ]。

然而，低血容量患者大量使用阿片类药物可能会恶化血流动力学状态。由于分布和清除体积减少，出血期间芬太尼的血浆浓度可能加倍。交感神经系统的激活通过增加心率和全身血管阻力来维持低血容量时的心输出量[ 3 ]。芬太尼通过其交感神经作用，可以阻碍这些机制，加剧血流动力学不稳定，特别是在高剂量时。正是出于这个原因，使用有限剂量的阿片类药物（例如 1 μg.kg ^-1芬太尼）对休克患者进行快速序列诱导[ 4 ]。一旦建立有效的容量复苏并且血压升高，可以等分滴定芬太尼以扩张微循环并恢复组织灌注，血清乳酸和碱缺乏的减少就证明了这一点[ 5 ]。

为了促进血流动力学稳定性，我们建议产科出血患者的麻醉管理应与创伤和休克患者的麻醉管理更加相似，明智地使用阿片类药物和氯胺酮等药物进行诱导。相反，“心脏麻醉剂”应该留给患有心脏病的人。