Diffusion function is a measurement in gas exchange function. It is used to evaluate the efficiency of gas exchange by the alveolar capillary membranes, as well as the examination of lung function. A decrease should be noted as a possibility caused by respiratory disease. Diffusion disorders are seen in reduced diffusion membrane area, such as obstructive emphysema; interstitial edema, alveolar wall thickening, and fibrous alveolar capillary changes, such as diffuse interstitial fibrosis, pneumoconiosis, tuberculosis, and diffuse fine bronchioloalveolar carcinoma. What are the examination methods for diffusion disorder? 1, Spirometer test Spirometer test is currently the most commonly used pulmonary ventilation function test, including time spirometry and flow volume curve. At present, most of the spirometers have been computerized, the time is recorded automatically by the computer, and the respiratory volume and flow rate can be measured at the same time and instantaneously, and the method of its determination is detailed in the determination of flow-volume curve. 2.Lung ventilation imaging Lung ventilation imaging is through the inhalation of 99mTc-labeled aerosol or radioactive gas (such as 81s krypton) to show the distribution of lung ventilation. Clinically, it is used to understand the smoothness of the respiratory tract and the ventilation function of various lung diseases, and can also be used to estimate the local lung ventilation function before and after drug or surgical treatment to guide the treatment and observe the efficacy of the treatment, and it is often used in conjunction with pulmonary perfusion imaging for the diagnosis and differential diagnosis of pulmonary embolism and obstructive lung disease. The diagnosis can be made by clinical examination of spirometry. It is (28.84±4.84) ml/(mmHg?min) in men and (22.13±3.09) ml/(mmHg?min) in women. Below this value, there is a decrease in gas diffusion function. It is important that you should go to the respiratory department of a regular hospital and pay attention to the standardization of the examination and so on.