Clinical scenarios for the idiopathic pulmonary fibrosis (IPF) patient presenting in the emergency department with subacute/acute dyspnea. (a) Progression to the final end of the disease. (b) 'True' IPF exacerbation. (c) IPF exacerbation due to treatable causes. Acute exacerbation (AE) criteria are presented in . For details about laboratory tests and blood/sputum/bronchoalveolar lavage (BAL) tests, see the 'Clinical and laboratory assessment' section. Cardiac echo, cardiac echocardiography; CTPA, computed tomography pulmonary angiography; HRCT, high-resolution computed tomography; ICU, intensive care unit; PE, pulmonary embolism; PH, pulmonary hypertension; PNX, pneumothorax; proBNP, pro-brain natriuretic peptide.