Disease Definition
Asthma is formally classified as a chronic inflammatory disorder of the respiratory airways characterized by three distinct pathophysiologic processes that work together: 3, 2
- Chronic airway inflammation involving multiple cellular players including mast cells, eosinophils, T lymphocytes, macrophages, and epithelial cells 1, 3
- Bronchial hyperresponsiveness where airways develop an exaggerated bronchoconstrictor response to stimuli that would not affect normal airways 3, 4
- Airway remodeling with permanent structural changes including sub-basement membrane fibrosis, smooth muscle hypertrophy, epithelial cell injury, and mucus gland hyperplasia 3, 4
Clinical Manifestations of the Disease
The disease manifests through recurrent episodes of specific respiratory symptoms: 1, 2
- Wheezing, shortness of breath, chest tightness, and cough that are characteristically variable, intermittent, worse at night, and provoked by specific triggers 1, 5
- Variable and reversible airflow obstruction that distinguishes it from fixed obstructive diseases, though some patients may develop incompletely reversible airflow limitation despite aggressive treatment 1, 3, 2
Pathophysiologic Basis
The underlying disease process involves: 1, 3
- Persistent inflammation present even in patients with mild asthma when they have few symptoms, with characteristic pathological features including inflammatory cells, plasma exudation, edema, smooth muscle hypertrophy, mucus plugging, and epithelial shedding 1
- Gene-environment interactions requiring both genetic susceptibility (80% of children with two asthmatic parents develop asthma) and environmental triggers for disease development 3, 6
Disease Classification
Asthma is recognized as a heterogeneous disease with multiple phenotypes including allergic asthma, cough-variant asthma, occupational asthma, and non-asthmatic eosinophilic bronchitis, each with varying patterns of inflammation and therapeutic responses. 1, 6, 7