Association between trajectories of end-tidal carbon dioxide and return of spontaneous circulation among emergency department patients with out-of-hospital cardiac arrest

Abstract

BackgroundWe aimed to identify distinct trajectories of end-tidal carbon dioxide (EtCO2) during cardiopulmonary resuscitation in patients with out-of-hospital cardiac arrest (OHCA) and to investigate the association between EtCO2 trajectories and OHCA outcomes. MethodsThis was a secondary analysis of a prospectively collected database on adult patients with OHCA who had been resuscitated in the emergency department of a tertiary medical center between 2015 and 2020. The primary outcome was the return of spontaneous circulation (ROSC). Group-based trajectory modelling was used to identify the EtCO2 trajectories. Multivariable logistic regression analysis was performed to evaluate the association between EtCO2 trajectories and ROSC. The predictive performance of the EtCO2 trajectories was assessed using the area under the receiver operating characteristic curve (AUC). ResultsThe study comprised 655 patients with OHCA. In the primary analysis, three distinct EtCO2 trajectories, including 10-mmHg, 30-mmHg, and 50-mmHg trajectories, were identified. Compared with the 10-mmHg trajectory, both 30-mmHg (odds ratio [OR]: 4.66, 95% confidence interval [CI]: 3.15–6.90) and 50-mmHg (OR: 7.58, 95% CI: 4.30–13.35) trajectories were associated with a higher likelihood of ROSC. In a sensitivity analysis of excluding EtCO2 measured before tracheal intubation or after sodium bicarbonate administration, the predictive ability of the identified EtCO2 trajectories remained. As a single predictor of ROSC, EtCO2 trajectories had an acceptable discriminative performance (AUC: 0.69, 95% CI: 0.66–0.73). ConclusionThree distinct EtCO2 trajectories during cardiopulmonary resuscitation were identified and significantly associated with outcomes. Early identification of these EtCO2 trajectories could potentially guide the ongoing resuscitation efforts.