The trial will last for six months. Patients will be collected clinical and anthropometric data by using questionnaires initially. Patients will have the pulmonary function test and CT scan and conduct 6MWT every two months. And Borg scale data will be collected every two months. The application of EPAP (15cmH2O) via face mask will be randomized with the help of opaque envelopes.
The purpose of this study is to evaluate the safety and the effects and of the application of Expiratory Positive Airway Pressure (EPAP) device on Dynamic Hyperinflation and dyspnea in patients with Emphysema and pulmonary bullae.