Symptoms (1) Chronic cough: usually the first symptom. At first the cough is intermittent, heavier in the morning, and then morning and evening or throughout the day, but the cough is not significant at night. In a few cases, the cough is not accompanied by sputum. In some cases, the cough is not accompanied by sputum, although there is obvious airflow limitation without coughing symptoms. (2) Coughing up sputum: After coughing up sputum, usually a small amount of mucus sputum is coughed up, and some patients have more sputum in the early morning; the amount of sputum increases in the case of co-infection, and there is often purulent sputum. (3) Shortness of breath or difficulty in breathing: this is the hallmark symptom of COPD, and is the main cause of anxiety for the patients. In the early stage, it only occurs when they are exerting themselves, and then it gradually worsens to the extent that they feel short of breath during daily activities or even when they are resting. (4) Wheezing and chest tightness: they are not specific symptoms of COPD. Some patients, especially those with severe COPD, have wheezing; chest tightness usually occurs after exertion, which is related to the effort of whistling and isovolumic contraction of intercostal muscles. (5) Systemic symptoms: In the clinical course of the disease, especially in the more severe patients, systemic symptoms may occur, such as weight loss, loss of appetite, peripheral muscle atrophy and dysfunction, depression and/or anxiety. Blood sputum or hemoptysis may be coughed up when combined with infection. (1) Smoking history: most of the patients have a long history of heavy smoking. (2) Occupational or environmental exposure to harmful substances: such as long-term exposure to dust, fumes, harmful particles or gases. (3) Family history: COPD has a tendency of family aggregation. (4) Age of onset and season of prevalence: the disease develops after middle age, and the symptoms occur in the cold season of fall and winter, and there is often a history of recurrent respiratory infections and acute exacerbations. Acute exacerbations become more frequent as the disease progresses. (5) History of chronic pulmonary heart disease: hypoxemia and hypercapnia occur in the late stage of COPD, which can be complicated by chronic pulmonary heart disease and right heart failure.