Bronchial asthma is a:

Ref: Global initative for bronchial asthma(GINA) guidelines, Harrison's principles of internal medicine 17th ed chapter 248Explanation:Asthma is a chronic inflammatory disorder of the airways.There is airway hyper responsiveness and associated variable airflow obstruction which is reversible spontaneously or with treatment.Simple spirometry confirms airflow limitation with a reduced FEV1, FEV1/FVC ratio, and PEF.The important differentiating feature of asthma from COPD is the characteristic reversible airflow limitation which is demonstrated by a >12% or 200 mL increase in FEV1 15 min after an inhaled short-acting beta2 agonist or. in some patients, by a 2- to 4-week trial of oral glucocorticoids.The diffusion studies in asthma are usually normal as there is no involvement of the alveolar- interstitial membrane.