Discriminatory Ability and Survival According to CaO₂.

A: ROC curves comparing the predictive ability of arterial oxygen content (CaO₂) and arterial partial pressure of oxygen (PaO₂) to predict mortality. CaO₂ showed greater discriminatory ability, evidenced by a higher area under the curve (AUC) compared to PaO₂. B: Kaplan-Meier survival curves stratified according to CaO₂ levels (high, normal, and low). Patients with low CaO₂ had lower cumulative survival over time, suggesting a significant association between reduced CaO₂ and mortality.