F2 and respiratory failure: We built a nomogram and evaluated its discrimination, calibration, and clinical utility with ROC curves, calibration plots, and decision curve analysis (DCA).<h4>Results</h4>Eight independent predictors entered the nomogram: respiratory failure (RF), chronic obstructive pulmonary disease (COPD), prothrombin time (PT), glucose, blood urea nitrogen (BUN), white blood cell count (WBC), albumin-to-alkaline phosphatase ratio (AAPR), and lactate-albumin ratio (LAR).