NPPB and acute respiratory distress syndrome: 2.6 ROC curve analysis of cardiopulmonary ultrasound+NT-proBNP+ PaO2/FiO2 diagnosing ARDS: The above combination was of high value with AUROC> 0.920 on day 1, day 2 and day 3; In which, the diagnostic value was the highest on day 2, with sensitivity, specificity and AUROC of 0.939,0.889 and 0.965, respectively (Table 7).