Definition
Although chronic bronchitis is defined officially in clinical terms, this condition is a chronic inflammation
of the trachea, bronchi and bronchioles which is characterized by hypersecretion
of mucous and thickening of the walls of respiratory tree. A
patient has chronic bronchitis when he or she has a persistent, productive cough
for at least 3 months in at least 2 consecutive years.
Pathology
How are the tubes of the respiratory tree narrowed?
- Excessive mucus secretions in the lumina of the respiratory
tree.
- Marked increase in the size of the mucus secreting glands of the
submucosa in the trachea and large bronchi. The Reid
Index is a ratio of the thickness of the gland layer to the thickness of the
submucosa. The ratio is increased in chronic bronchitis.
- Marked increase in goblet cells in small
bronchi and bronchioles.
- Squamous metaplasia and dysplasia of
bronchial epithelium.
Pathogenesis
- Inhaled irritants such as smoking.
- Infections.
Pathophysiology
Persistent, productive cough; dyspnea; expiratory wheezing.
