This disease is caused by chronic purulent inflammation and fibrosis of the bronchi and surrounding lung tissues, which destroys the muscles and elastic tissues of the bronchial walls and leads to deformation and persistent dilatation of the bronchi, with the typical symptom of chronic coughing and coughing up large amounts of pus sputum accompanied by repeated coughing up blood. After coughing up the sputum, it can be divided into three layers: the upper layer is mainly foamy sputum, the middle layer is mainly plasma, and the lower layer is composed of necrotic tissue and pus masses. If not actively treated, it can cause pleurisy, pulmonary heart disease, and in severe cases, heart failure.