Bronchial excitation test Bronchial excitation test is to use some kind of stimulation to make the bronchial smooth muscle contraction, and then use the lung function as an index to determine the degree of bronchial stenosis, which is used to determine the airway hyperresponsiveness (AHR). Its clinical application is mainly to assist in the diagnosis of asthma, as a reference index for asthma treatment, and to study the pathogenesis of asthma and other diseases. Commonly used inhalation stimulants are acetylmethacholine and histamine, other stimulants include allergens, adenosine monophosphate, mannitol, hypertonic saline, etc. Physical stimulants such as exercise and cold air are also used as stimulants. Observations included first second expiratory volume of exertion, maximum expiratory flow, and so on. The judgment of the result is related to the excitatory agent used, and is usually expressed in terms of the cumulative dose or concentration of inhaled acetylmethacholine or histamine required to cause a 20% decrease in the first-second expiratory volume with exertion. If the first-second expiratory volume with exertion decreases by ≥20%, the result is judged to be positive, suggesting the presence of airway hyperresponsiveness. The bronchial provocation test is indicated in patients with non-asthmatic exacerbations who have a first-second expiratory volume above 70% of the normal expected value.