Resuscitation From Out-of-Hospital Cardiac Arrest: When Is EtCO2 Reliably Associated With ROSC?

However, the minimum EtCO2 monitoring duration needed to discriminate return of spontaneous circulation (ROSC) from non-ROSC remains unknown.

然而，监测EtCO2的最短时间以区分自主循环恢复（ROSC）与非ROSC仍不清楚。

We sought to determine the EtCO2 trajectory observation time required to differentiate ROSC from non-ROSC patients.

我们试图确定区分恢复自主循环(ROSC)患者与非恢复自主循环(non-ROSC)患者所需的呼气末二氧化碳(EtCO2)轨迹观察时间。

Methods

We performed a secondary analysis of the cluster-randomized Pragmatic Airway Resuscitation Trial (PART), which assessed endotracheal intubation or laryngeal tube strategies in OHCA resuscitation.

我们对集群随机化的实用气道复苏试验(PART)进行了二次分析，该试验评估了在院外心脏骤停(OHCA)复苏中使用气管插管或喉罩管策略的效果。

We summarized mean EtCO2 in 1-minute epochs over the resuscitation.

我们总结了复苏期间每分钟时段的平均呼气末二氧化碳（EtCO2）值。

Cases were stratified a priori by: (1) witnessed versus unwitnessed status, and (2) initial EtCO2: low (≤30 mm Hg), moderate (31-49), and high (≥50).

病例事先根据以下标准进行分层：(1) 是否有人目击，以及(2) 初始EtCO2水平：低（≤30毫米汞柱）、中等（31-49毫米汞柱）和高（≥50毫米汞柱）。

Within each stratum, group-based trajectory modeling (GBTM) was used to identify latent EtCO2 trajectory classes, and patients were categorized into an upward or downward trajectory.

在每个层内，使用基于群体的轨迹建模（GBTM）来识别潜在的EtCO2轨迹类别，患者被归类为上升或下降轨迹。

To balance trajectory groups on baseline characteristics including age, sex, race, initial rhythm, location, and bystander CPR, we applied inverse probability of treatment weighting.

为了在包括年龄、性别、种族、初始节律、地点和旁观者CPR在内的基线特征上平衡轨迹组，我们应用了治疗权重的逆概率。

We fit weighted pooled logistic regression models to estimate risk ratios (RRs) for ROSC comparing upward versus downward EtCO2 trajectories.

我们拟合了加权汇总逻辑回归模型，以估计比较上升与下降的呼气末二氧化碳（EtCO2）轨迹时，获得恢复自主循环（ROSC）的风险比（RRs）。

Within each stratum, we identified the earliest minute when CIs between upward versus downward EtCO2 trajectories no longer overlapped.

在每个层内，我们确定了最早的一分钟，此时上升与下降的呼气末二氧化碳（EtCO2）轨迹之间的置信区间（CIs）不再重叠。

Results

EtCO2 data were available for 1168 patients: 452 (38.6%) witnessed and 716 (61.1%) unwitnessed.

EtCO2数据可用于1168名患者：452名（38.6%）为目击者，716名（61.1%）为非目击者。

Patients were predominantly men (63.5%), with a median age of 65 years (Q1, Q3: 53-75), majority White race (51.3%), and presenting in a nonpublic setting (85.4%).

患者主要为男性（63.5%），中位年龄为65岁（四分位数间距：53-75），大多数为白人（51.3%），并且在非公共场合出现（85.4%）。

Overall ROSC was 18.2%: 30.5% of witnessed and 10.5% of unwitnessed.

总体恢复自主循环(ROSC)的比例为18.2%：其中目击到的为30.5%，未目击到的为10.5%。

Among witnessed arrests, 95% CI for upward versus downward EtCO2 trajectories no longer overlapped at 8 minutes for low initial EtCO2 (RR, 3.06; 95% CI, 1.49, 6.71), 12 minutes for moderate EtCO2 (RR, 1.95; 95% CI, 1.23, 3.48), and 21 minutes for high EtCO2 (RR, 2.12; 95% CI, 1.30, 3.73).

在目击到的心脏骤停中，初始EtCO2水平低的病例在8分钟时，向上与向下的EtCO2轨迹的95%置信区间不再重叠（相对风险，RR，3.06；95%置信区间，1.49, 6.71），初始EtCO2水平中等的病例在12分钟时（RR，1.95；95%置信区间，1.23, 3.48），初始EtCO2水平高的病例在21分钟时（RR，2.12；95%置信区间，1.30, 3.73）。

Among unwitnessed arrests, nonoverlapping CIs were first observed at 7 minutes (RR, 3.56; 95% CI, 1.53, 10.37).

在未目击的心脏骤停中，首次观察到非重叠的置信区间是在7分钟时（相对风险，3.56；95%置信区间，1.53至10.37）。

Conclusions

Depending on witness status and initial EtCO2, between 7 and 21 minutes of monitoring are needed to reliably differentiate upward from downward EtCO2 trajectories during OHCA resuscitation.

根据目击状态和初始呼气末二氧化碳（EtCO2），在心搏骤停复苏期间，需要7至21分钟的监测时间，以可靠地区分EtCO2轨迹的上升和下降。

Dynamic EtCO2 trajectory monitoring may provide early prognostic information to guide resuscitation.

动态监测呼气末二氧化碳（EtCO2）轨迹可能提供早期预后信息以指导复苏。