COPD is the abbreviation of chronic obstructive pulmonary disease. COPD is a group of respiratory diseases caused by chronic airway inflammation, mainly due to restricted expiratory flow rate and incomplete reversibility. the diagnostic criteria of COPD are mainly based on medical history, symptoms and signs, causative factors, chest X-ray, pulmonary function tests, etc. 1. medical history: common underlying diseases of COPD patients include chronic wheezing Chronic bronchitis, chronic obstructive pulmonary emphysema, recurrent chronic bronchial asthma, chronic bronchiectasis, and various types of pneumoconiosis, post lobectomy or compensatory emphysema due to spinal thoracic deformity, etc. Patients with the above medical history are prone to COPD; 2. Symptoms and signs: Patients have clinical symptoms of recurrent chronic cough, coughing and shortness of breath after activity. Examination may reveal different degrees of emphysema signs, such as barrel-shaped chest with enlarged anterior and posterior thoracic diameters and clear sound on percussion, etc.; 3. Causes: There may be a history of long-term smoking or hazardous environmental exposure during the course of the disease, such as long-term exposure to dust and interior decoration, etc.; 4. Chest X-ray: Chest X-ray shows different degrees of emphysema and pulmonary bullae, etc.; 5. Pulmonary function tests: Pulmonary function tests reveal that patients have expiratory flow rate limitation. Specifically, the percentage of the first second exertional lung volume (FEV1) to exertional lung volume (FVC) is lower than 70%, and after inhalation of bronchodilator, the airflow limitation will not be improved, and FEV1/FVC is still lower than 70%. The severity of pulmonary impairment in COPD patients can be judged not only on the basis of FEV1, but also on the basis of the degree of reduced FEV1/FVC. In addition, before diagnosing COPD, it is necessary to exclude other diseases that cause expiratory flow rate limitation, such as acute attacks of bronchial asthma, acute heart failure, etc. Pulmonary stasis, etc. An FEV1/FVC percentage of less than 70% can be used to determine respiratory airflow limitation. COPD can be diagnosed if the above triggers, medical history and clinical symptoms are present.