Pink frothy sputum is most often caused by infiltration of fluid from the capillaries into the interstitium or alveoli. The common clinical pulmonary edema is cardiogenic pulmonary edema and renal pulmonary edema. So, what are the tests for patients who cough up pink foamy sputum? The following is a description of the examination items for coughing up pink foamy sputum: 1. X-ray examination Chest X-ray orthopantomograph shows thoracic dilatation, bilateral widening of the intercostal space, flattening of the ribs, weakening of the thoracic discourse, lowering and flattening of the diaphragm, increased translucency in the lung fields bilaterally, and thinning of the pulmonary vein texture. The pulmonary vascular texture was thin, sparse and straightened in the outer bands, and thickened and disorganized in the inner bands. The cardiac shadow is pendulous and narrow. In some patients, a limited increase in translucency is seen, suggesting limited emphysema or pulmonary alveoli. Some patients with emphysema also have increased pulmonary texture and widened pulmonary arteries due to the combination of early pulmonary heart disease and pulmonary hypertension. Lateral chest radiographs show increased anteroposterior diameter of the thorax and enlarged retrosternal space. Electrocardiogram (ECG) is usually without abnormalities, and sometimes can be low voltage. 3.Respiratory function examination is important for the diagnosis of obstructive pulmonary emphysema. The diagnosis of emphysema is as follows: ① Ventilation dysfunction, such as the ratio of expiratory volume in the first second to expiratory volume in the first second is FEVl<60%, the maximal ventilation is lower than 80% of the predicted value, and expiratory flow rate decreases in the curve of maximal respiratory flow rate. (iii) Decreased lung capacity, increased residual air and total lung volume, and a residual air/total lung ratio >40% indicate lung hyperinflation. (iii) Some patients showed reduced lung diffusion function. (iv) There is no significant improvement in lung function after treatment with bronchodilators, and the amount of residual gas is increased. 4.Blood gas analysis Arterial blood gas analysis Often appears obvious hypoxia and carbon dioxide retention when the partial pressure of oxygen (PaO2) of arterial blood is reduced, the partial pressure of carbon dioxide (PaC02) is increased, and may appear to be uncompensated respiratory acidosis, the pH value is reduced. 5. Blood and sputum examination.