The following is a summary of “PCO2 on arrival as a predictive biomarker in patients with out-of-hospital cardiac arrest,” published in the July 2023 issue of Emergency Medicine by Inoue et al.

To make clinical decisions, treating out-of-hospital cardiac arrest (OHCA) necessitates an early outcome prognosis, ideally upon hospital arrival. This study investigated whether the partial pressure of carbon dioxide (PCO₂) at the time of OHCA patient admission is associated with one-month survival. This retrospective study was conducted at a single center on adult OHCA patients treated between January 2016 and December 2020. By the Cerebral Performance Category (CPC) scale, outcomes were categorized. The primary outcome was one-month mortality (CPC 5). 

Death or unfavorable neurological outcome (CPC 3–5) and unfavorable neurological outcome (CPC 3–4) at one month were secondary outcomes. Age, gender, witnessed cardiac arrest, bystander cardiopulmonary resuscitation, initial shockable rhythm, and delay from call to emergency medical services to hospital arrival were accounted for in a multivariable analysis. During the study period, 19 OHCA patients were precluded. They were younger than 18 years old, 79 because they received extracorporeal cardiopulmonary resuscitation, and 101 because they lacked PCO₂ data. 

This study involved a total of 778 patients; mortality (CPC 5) at one month was observed in 706 (90.7%), death or adverse neurological outcome (CPC 3–5) in 743 (95.5%), and negative neurological development (CPC 3–4) in 37 (4.8%). In multivariable analysis, high PCO₂ levels showed significant association with mortality (CPC 5) at one month (odds ratio [OR] [per 5 mmHg], 1.14; 95% CI, 1.08–1.21), death or unfavorable neurological outcome (CPC 3–5) (OR [per 5 mmHg], 1.29; 95% CI, 1.17–1.42), and unfavorable neurological outcome (CPC 3–4) (OR [per 5 mmHg], 1.21; 95% CI, 1.04–1.41). In OHCA patients, a high PCO₂ at presentation was significantly associated with mortality and a poor neurological outcome.

Source: sciencedirect.com/science/article/abs/pii/S0735675723002036