Determination of pulmonary function
According to the basic guidelines for routine pulmonary function examination ( 2018 ) [14] and ATS-ERS guidelines [15], use the MSDIFFUSION APS pulmonary function tester produced by Yege Company, German, which measures the forced vital capacity ( FVC ) , takes one second forced expiratory volume ( FEV1 ) , one-second rate ( FEV1 / FVC ) and measuring carbon monoxide dispersion with one breath ( DLCO ) . Pulmonary ventilation dysfunction is FEV1 / pred < 80%, FEV1 / FVC < 70%, diffuse pulmonary dysfunction DLCO accounts for less than 80% of the predicted value, and small airway dysfunction is FEF50%, FEF75%, FEF25-75% ( MMEF ) 2 out of 3 items are lower than 65% of the predicted value.