Abstract 251: Association Between Early Arterial Blood Gas Levels and Neurological Outcome in Adult Patients Following In-Hospital Cardiac Arrest

Abstract

Background: 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. Recent guidelines for the management of cardiac arrest recommend maintaining the arterial oxyhemoglobin saturation at ≥ 94% and PaCO2 at 40-45 mm Hg after successful resuscitation of patients sustaining cardiac arrest. However, there are few clinical studies that have investigated the relationship of early PaO2 and PaCO2 to the neurological outcomes of resuscitated patients or determined the optimal values for PaO2 and PaCO2. Methods and Results: This was a retrospective observational study from a single medical center of adult patients who had in-hospital cardiac arrest and achieved sustained return of spontaneous circulation (ROSC) between 2006 and 2012. Multivariable logistic regression analysis was used to identify factors associated with favorable neurologic outcome at hospital discharge. A general additive model was used to detect nonlinear relationships between independent and dependent variables. The first PaO2 and PaCO2 values measured after first sustained ROSC were used for analysis. Of the 550 study patients, 154 (28%) survived to hospital discharge and 74 (13.5%) achieved favorable neurologic outcome. The mean time from sustained ROSC to the measurement of PaO2 and PaCO2 was 136.8 minutes. The mean PaO2 and PaCO2 were 167.4 mm Hg and 40.3 mm Hg, respectively. PaO2 between 70 and 240 mmHg (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 were correlated with neurological outcome of patients with in-hospital cardiac arrest. PaO2 levels between 70 and 240 mm Hg were associated with favorable neurological function at hospital discharge, while higher PaCO2 levels might be associated with adverse outcomes.