Introduction

End-tidal carbon dioxide (ETCO2) has been suggested to have prognostic implications during out-of-hospital cardiac arrest (OHCA). Our objective was to determine if the change in ETCO2 (delta ETCO2) during resuscitation was predictive of future return of spontaneous circulation (ROSC) in patients with pulseless electrical activity (PEA) arrests.

Methods

We performed a retrospective, observational study of adult (≥18 years of age) non–traumatic PEA OHCAs in two Canadian EMS systems over a two-year time frame beginning on January 1, 2018. Cases were excluded if there was a Do Not Resuscitate order (DNR), had no advanced airway, or had less than two ETCO2 recordings. We performed multivariable logistic regression to examine the association between ETCO2 measures and ROSC. Second, we examined the prognostic performance (sensitivity, specificity, NPV, PPV) for ETCO2 at specific thresholds for predicting ROSC.

Results

A total of 208 OHCA met inclusion criteria of which 67 (32%) obtained ROSC. After adjusting for pre-determined confounders, there was an association between delta ETCO2 and ROSC (odds ratio [OR] per 10 mmHg increase in ETCO2 of 1.74 (95% confidence interval [CI] 1.35 to 2.24); P value < 0.001). We also found significant associations between both initial ETCO2 and final ETCO2 with ROSC.

Conclusion

Our analysis indicates that there is a positive linear relationship between delta ETCO2 and ROSC with values of delta ETCO2 > 20 mmHg being highly specific for ROSC in PEA patients. As such, patients with up-trending ETCO2 values should have resuscitation continued unless there is overwhelming clinical evidence to the contrary.

中文翻译：

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呼气末 CO2 与无脉搏电活动的院外心脏骤停后自主循环恢复之间的关系

介绍

呼气末二氧化碳 (ETCO2) 被认为对院外心脏骤停 (OHCA) 的预后有影响。我们的目标是确定复苏期间 ETCO2 (delta ETCO2) 的变化是否可以预测无脉搏电活动 (PEA) 骤停患者未来自主循环 (ROSC) 的恢复。

方法

我们在 2018 年 1 月 1 日开始的两年时间范围内对两个加拿大 EMS 系统中的成人（≥18 岁）非创伤性 PEA OHCA 进行了一项回顾性观察性研究。订单 (DNR)、没有高级气道或少于两个 ETCO2 记录。我们进行了多变量逻辑回归来检查 ETCO2 测量值与 ROSC 之间的关联。其次，我们在预测 ROSC 的特定阈值下检查了 ETCO2 的预后性能（敏感性、特异性、NPV、PPV）。

结果

共有 208 名 OHCA 符合纳入标准，其中 67 名（32%）获得 ROSC。调整预先确定的混杂因素后，delta ETCO2 和 ROSC 之间存在关联（ETCO2 每增加 10 mmHg 的比值比 [OR] 为 1.74（95% 置信区间 [CI] 1.35 至 2.24）；P 值 < 0.001）。我们还发现初始 ETCO2 和最终 ETCO2 与 ROSC 之间存在显着关联。

结论

我们的分析表明，delta ETCO2 和 ROSC 之间存在正线性关系，其中 delta ETCO2 > 20 mmHg 的值对 PEA 患者的 ROSC 具有高度特异性。因此，除非有压倒性的相反临床证据，否则 ETCO2 值呈上升趋势的患者应继续复苏。