There are two main types of thoracic occlusion drainage, including drainage of gas and drainage of fluid, namely pneumothorax and pleural effusion, and the drainage flow rates are as follows: 1. gas drainage is based on negative pressure drainage, generally there is 4cmH2O in the drainage bottle, and the drainage flow rate is not clearly defined by data; 2. if the closed chest drainage fluid, the first time should not exceed 700ml. the second and third time can slowly increase, and in general, also to 1000ml is the limit. Because putting too much or too often, the pressure in the chest cavity drops, the lungs reopen too quickly, which may cause acute pulmonary edema, or even cause cardiac insufficiency, shock occurs. Therefore, in general, drainage of fluid should also be slow and should be less than 1000ml.