2.Etiology A. Bronchial and pulmonary disorders: chronic bronchitis complicated with COPD 80-90% asthma. bronchiectasis. tu berculosis. silicosis chronic interstitial lung disease B. Disorders of chest movement: (rare) abnormality, adhesion, vertebral tuberculosis rhumatoid spondylitis2.Etiology A. Bronchial and pulmonary disorders： chronic bronchitis complicated with COPD: 80－90% asthma, bronchiectasis, tuberculosis, silicosis, chronic interstitial lung disease B. Disorders of chest movement:（rare） abnormality, adhesion, vertebral tuberculosis、 rhumatoid spondylitis