- American Thoracic Society (ATS) (1987) defines asthma as a:
- Clinical syndrome characterized by increased responsiveness of the tracheo-bronchial tree to a variety of stimuli. Major symptoms are paroxysms of dyspnea, wheezing and cough, which may vary from mild and almost undetectable to severe and unremitting (status asthmaticus).
Primary physiologic manifestation of this hyper-responsiveness is variable airway obstruction, in the form of fluctuations in the severity of obstruction after bronchodilator or corticosteroid use, or increased obstruction caused by drugs or other stimuli, as well as evidence of mucosal edema of bronchi, infiltration of bronchial mucosa or submucosa with inflammatory cells (especially eosinophils), shedding of epithelium, and obstruction of peripheral airways with mucus. | | | | | |