Abstract 216: Association Between Trajectories Of End-tidal Carbon Dioxide And Return Of Spontaneous Circulation Among Emergency Department Patients With Out-of-hospital Cardiac Arrest: A Retrospective Analysis Of A Prospective Registry

Abstract

Introduction: The level of end-tidal carbon dioxide (EtCO 2 ) reflects the blood flow generated by cardiopulmonary resuscitation (CPR). Static EtCO 2 parameters, such as average EtCO 2 levels, has been reported to be associated with outcomes following out-of-hospital cardiac arrest (OHCA). Hypothesis: Distinct trajectories of EtCO 2 during CPR was associated with OHCA outcomes. Methods: This was a retrospective analysis of a prospectively collected database on patients with OHCA who had been resuscitated in the emergency department of a tertiary medical center between 2015 and 2020. Adult patients with ≥3 measurements of EtCO 2 were included. The primary outcome was the return of spontaneous circulation (ROSC). Group-based trajectory modelling was used to identify the EtCO 2 trajectories. Multivariable logistic regression analysis was performed to evaluate the association between EtCO 2 trajectories and ROSC. The predictive performance of the EtCO 2 trajectories was assessed using the area under the receiver operating characteristic curve (AUC). Results: The study comprised 655 patients with OHCA. In the primary analysis, three distinct EtCO 2 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 EtCO 2 measured before tracheal intubation or after sodium bicarbonate administration, the predictive ability of the identified EtCO 2 trajectories remained. As a single predictor of ROSC, EtCO 2 trajectories had an acceptable discriminative performance (AUC: 0.69, 95% CI: 0.66-0.73). Conclusion: Three distinct EtCO 2 trajectories during CPR were identified and significantly associated with OHCA outcomes, which may assist in guiding the ongoing resuscitation efforts.