The clinical symptoms of COPD are chronic progressive dyspnea, shortness of breath, coughing and sputum, the most typical symptom is dyspnea, which is aggravated by activity, and chronic coughing and sputum, which is sticky and not easy to cough up, as well as white sputum, etc. Some patients also hear a croupy sound in the throat and feel a tightening sensation in the chest. Severe and very severe patients may also have other symptoms, such as fatigue, weight loss, loss of appetite, depression, etc. The common signs of COPD are abnormal thoracic shape, large anterior and posterior diameters, shallow breathing, increased frequency, and hypoxemia, such as cyanosis and darkness of mucous membranes, skin and nails.