Pulmonary ventilation refers to the process of exchange of alveolar gases with blood gases, through some mechanism, a process that is directly related to the area and thickness of the alveolar membrane, as well as the diffusion capacity of the gas. Pulmonary gas exchange disorder, also called diffusion dysfunction, refers to the obstruction of this process and its inability to proceed properly and efficiently. It is related to the area of the alveolar membrane, the partial pressure difference of the gas on both sides of the alveolar membrane, and the molecular weight and solubility of the gas in several ways. The normal adult alveolar membrane area is 50-60 square meters, which can also be increased during exercise, so the organism has a normal and huge reserve. The main diseases that cause a decrease in alveolar membrane surface are pulmonary solids, pulmonary atelectasis, lobectomy and pulmonary alveoli.2. Uneven thickness of normal respiratory membranes can also lead to impaired gas exchange, and the main diseases are pulmonary fibrosis, pulmonary edema, interstitial pneumonia, alveolar hyaline membrane formation and edema.