Background Hypotension following intubation and return of spontaneous circulation (ROSC) after cardiac arrest is associated with poorer patient outcomes. In patients with a sustained ROSC requiring emergency anaesthesia, there is limited evidence to guide anaesthetic practice. At the Essex & Herts Air Ambulance Trust, a UK-based helicopter emergency medical service, we assessed the relative haemodynamic stability of two different induction agents for post-cardiac arrest medical patients requiring prehospital emergency anaesthesia (PHEA). Methods We performed a retrospective database review over a 5-year period between December 2014 and December 2019 comparing ketamine-based and midazolam-based anaesthesia in this patient cohort. Our primary outcome was clinically significant hypotension within 30 min of PHEA, defined as a new systolic BP less than 90 mm Hg, or a 10% drop if less than 90 mm Hg before induction. Results One hundred ninety-eight patients met inclusion criteria. Forty-eight patients received a ketamine-based induction, median dose (IQR) 1.00 (1.00–1.55) mg/kg, and a 150 midazolam-based regime, median dose 0.03 (0.02–0.04) mg/kg. Hypotension occurred in 54.2% of the ketamine group and 50.7% of the midazolam group (p=0.673). Mean maximal HRs within 30 min of PHEA were 119 beats/min and 122 beats/min, respectively (p=0.523). A shock index greater than 1.0 beats/min/mm Hg and age greater than 70 years were both associated with post-PHEA hypotension with ORs 1.96 (CI 1.02 to 3.71) and 1.99 (CI 1.01 to 3.90), respectively. Adverse event rates did not significantly differ between groups. Conclusion PHEA following a medical cardiac arrest is associated with potentially significant cardiovascular derangements when measured up to 30 min after induction of anaesthesia. There was no demonstrable difference in post-induction hypotension between ketamine-based and midazolam-based PHEA. Choice of induction agent alone is insufficient to mitigate haemodynamic disturbance, and alternative strategies should be used to address this. Data are available upon reasonable request. Data are available on reasonable request from the corresponding author or from our patient liaison managers.

中文翻译：

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内科心脏骤停后自主循环恢复患者院前紧急麻醉的心血管并发症：基于氯胺酮和基于咪达唑仑的诱导方案的回顾性比较

背景 插管后的低血压和心脏骤停后自主循环 (ROSC) 的恢复与较差的患者预后相关。对于需要紧急麻醉的持续 ROSC 患者，指导麻醉实践的证据有限。在总部位于英国的直升机紧急医疗服务 Essex & Herts Air Ambulance Trust，我们评估了两种不同诱导剂对需要院前紧急麻醉 (PHEA) 的心脏骤停后内科患者的相对血流动力学稳定性。方法 我们在 2014 年 12 月至 2019 年 12 月之间的 5 年期间进行了回顾性数据库审查，比较了该患者队列中基于氯胺酮和基于咪达唑仑的麻醉。我们的主要结果是 PHEA 后 30 分钟内有临床意义的低血压，定义为新的收缩压低于 90 mm Hg，或者如果在诱导前低于 90 mm Hg，则下降 10%。结果 198 名患者符合纳入标准。48 名患者接受了基于氯胺酮的诱导，中位剂量 (IQR) 1.00 (1.00–1.55) mg/kg，以及基于 150 咪达唑仑的方案，中位剂量 0.03 (0.02–0.04) mg/kg。54.2% 的氯胺酮组和 50.7% 的咪达唑仑组出现低血压 (p=0.673)。PHEA 30 分钟内的平均最大 HR 分别为 119 次/分钟和 122 次/分钟 (p=0.523)。休克指数大于 1.0 次/分钟/毫米汞柱和年龄大于 70 岁均与 PHEA 后低血压相关，OR 分别为 1.96（CI 1.02 至 3.71）和 1.99（CI 1.01 至 3.90）。不良事件发生率在各组之间没有显着差异。结论 医学心脏骤停后的 PHEA 与麻醉诱导后 30 分钟内测量的潜在显着心血管疾病相关。基于氯胺酮和基于咪达唑仑的 PHEA 在诱导后低血压方面没有明显差异。单独选择诱导剂不足以减轻血流动力学障碍，应使用替代策略来解决这一问题。可根据合理要求提供数据。数据可根据通讯作者或我们的患者联络经理的合理要求提供。单独选择诱导剂不足以减轻血流动力学障碍，应使用替代策略来解决这一问题。可根据合理要求提供数据。数据可根据通讯作者或我们的患者联络经理的合理要求提供。单独选择诱导剂不足以减轻血流动力学障碍，应使用替代策略来解决这一问题。可根据合理要求提供数据。数据可根据通讯作者或我们的患者联络经理的合理要求提供。