1, blood routine: eosinophils may increase during an attack; 2, sputum examination: mostly mucous sputum, eosinophils in sputum may also increase; 3, pulmonary function tests: the ratio of force expiratory volume in one second (FEV1) to force spirometry (FVC) and peak expiratory flow rate (PEFR) are used clinically to understand whether there is airflow restriction; FEV1/FVC <70%-75% indicates Airflow limitation, inhalation of bronchodilator
A 15% or greater increase after 15-20 minutes of inhalation of bronchodilator indicates reversible airflow limitation. 4. Chest X-ray: Most patients with asthma may have no significant abnormalities on chest radiographs, but some patients may have emphysema. Chest X-ray is mainly used to exclude other lung diseases; 5. Allergen testing: Intradermal testing of various allergens can detect suspected allergens. Serum allergen-specific IgE assay has some value, but total serum IgE assay does not have diagnostic significance.