Association between early arterial blood gas tensions and neurological outcome in adult patients following in-hospital cardiac arrest

Abstract

Objective: The early partial pressures of arterial O2 (PaO2) and CO2 (PaCO2) have been found in animal studies to be correlated with neurological outcome after brain injury. However, the relationship of early PaO2 and PaCO2 to the neurological outcomes of resuscitated patients after cardiac arrest was still not clear.

Methods: This was a retrospective observational cohort study in a single medical center. Adult patients who had in-hospital cardiac arrest between 2006 and 2012 and achieved sustained return of spontaneous circulation (ROSC) (ROSC>20min without resumption of chest compression) were included. Multivariable logistic regression analysis was used to identify factors associated with favorable neurological outcome at hospital discharge. The first PaO2 and PaCO2 values measured after first sustained ROSC were used for analysis.

Results: Of the 550 included patients, 154 (28%) survived to hospital discharge and 74 (13.5%) achieved favorable neurological outcome. The mean time from sustained ROSC to the measurement of PaO2 and PaCO2 was 136.8min. The mean PaO2 and PaCO2 were 167.4mmHg and 40.3mmHg, respectively. PaO2 between 70 and 240mmHg (odds ratio [OR] 1.96, 95% confidence interval [CI] 1.08-3.64) and PaCO2 levels (OR 0.98, 95% CI 0.95-0.99) were positively and inversely associated with favorable neurological outcome, respectively.

Conclusions: The early PaO2 and PaCO2 levels obtained after ROSC might be correlated with neurological outcome of patients with in-hospital cardiac arrest. However, because of the inherent limitations of the retrospective design, these results should be further validated in future studies.

Keywords: Carbon dioxide; Cardiopulmonary resuscitation; Critical care; Emergency medicine; Heart arrest; Oxygen.