Kim YW, et al. - In this retrospective observational study of post-cardiac arrest patients, researchers determined the predictive value of the gradient between arterial carbon dioxide (PaCO2) and end-tidal carbon dioxide (ETCO2) (Pa-ETCO2) for in-hospital mortality. Using multivariate logistic regression, the link between Pa-ETCO2 gap and clinical variables was verified and the cutoff value of Pa-ETCO2 for predicting in-hospital mortality was determined via receiver operating characteristic (ROC) curve analysis. The Pa-ETCO2 gap at 24 h after return of spontaneous circulation (ROSC) was shown to be related to inhospital mortality in post-cardiac arrest patients. With 77.8% sensitivity and 85.7% specificity, 10.6 mmHg was defined as the optimal cut-off value of Pa-ETCO2 gap at 24 h after ROSC in ROC curve analysis.