The purpose of respiratory function training is mainly several: firstly, to improve pulmonary ventilation. Second, to change the abnormal respiratory pattern into a normal one. Third, to increase the mobility of the thorax. Fourth, especially for some pre-surgical patients, respiratory training is to help him improve the effectiveness of coughing. Elderly patients with COPD need to perform cough training, which is breathing training to reduce the physiological dead space of the lungs, and then continuously improve the effectiveness of pulmonary breathing.