The main symptoms of exudative pleural fluid are dyspnea, normal temperature, and loud heart sounds. Chest wall percussion on both sides of the horizontal turbidity, the location of the turbidity boundary with the patient’s position changes. On auscultation, no alveolar sounds can be heard in the turbid zone, and sometimes bronchial breath sounds can be heard. It is often accompanied by ascites, pericardial effusion and subcutaneous edema. Diagnosis of exudative pleural fluid: 1, usually according to the routine examination of pleural fluid can be determined: the method of differentiation is often based on the specific gravity of pleural fluid (to 1.018 as the boundary), protein content (to 30g/L as the boundary), the number of nucleated cells (to 500 × 10^9/L as the boundary) to divide, less than the above boundary for leakage fluid, large dry above the boundary for exudative fluid. If the conventional examination can not completely determine the nature of pleural effusion, can adopt Light criteria, meet any one of the following can be diagnosed as exudate: ① pleural effusion and serum protein volume ratio > 0.5; ② pleural effusion and serum lactate dehydrogenase (LDH) ratio > 0.6; ③ pleural effusion LDH > 2/3 of the upper limit of the normal serum LDH (pleural effusion LDH > 200IU / L). L). 2, according to the lack of fever and other systemic symptoms and percussion level turbidity, it is not difficult to confirm the diagnosis: but must be distinguished from pleurisy. Pleurisy has fever, chest pain, cough, pleural friction sound, mostly occurring on one side, pleurisy is exudate, containing a large amount of fibrin and protein, Levarta’s reaction is positive. On the other hand, pleural fluid has no systemic symptoms, and the fluid in the chest cavity is leakage fluid, which is relatively clarified and thin, containing a small amount of fibrin and protein, and the Levatt’s reaction is negative.