Characterized by hyper-responsiveness of the airways - bronchospasm/constriction, increased mucous secretion, injury to mucosal lining, inflammation of the airway.
- Catagories: Catagories are often misleading and inaccurate.
- Allergic/Extrinsic (result of antigen-antibody reaction on mast cells of the respiratory tract. Childhood).
- Idiopathic/Intrinsic (implies its a result of imbalance of autonomic nervous system, generally no antibodies formed).
occurs within minutes, bronchospasm, mucosal edema, generally inhibited or reversed by bronchodilators (B2 agonists)
4-8 hours later, can last longer, might be associated with an early phase, invasion of inflammatory cells into damaged tissue (basophils, eosinophils, neutrophils), produced epithelial injury and edema.
Common provocative stimuli:
exposure to allergen, inhaled irritants, respiratory tract infection, exercise, cold air, humid air.
- -epithelial damage,
- -hypertrophy and hyperplasia of smooth muscle layer
- -thickening of epithelial basement membrane
- -enlargement of mucous secreting apparatus -edema/infiltrates or eosinophils in bronchial wall
- -narrowing of the airways (smooth muscle contractions, mucosal/submucosal edema)
- -increased airway resistance (espec. expiration)
- -non-uniform distribution of disease process (A/W resistance variable, ventilation variable, V/Q mismatch)
usually childhood asthma, wheezing/dyspnea with symptom free intervals, cough, dyspnea, wheezing chest tightness.