Bronchitis pathophysiology

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Seyedmahdi Pahlavani, M.D. [2]

Bronchitis Main page
Patient Information
Overview
Causes
Classification Acute bronchitis Chronic bronchitis
Differential Diagnosis

Overview

Bronchitis is the inflammatory response of the bronchial epithelium to infections or irritants. The pathophysiological finding seen with acute bronchitis include: thickening, hyperemia and edema of the bronchial mucosa. When process becomes chronic, decreases in the bronchial mucociliary function leads to airway clogging by debris which causes copious mucus secretion that causes the characteristic cough of bronchitis.

Pathophysiology

• Acute bronchitis:

Inflammatory response of the bronchial epithelium to infections or irritants that involve the medium and large size airways results in thickening of the bronchial and tracheal mucosa.

Bronchitis caused by influenza virus shows an epithelial-cell desquamation in association with the presence of a lymphocytic cellular infiltrate.

• Chronic bronchitis:

Halmark features include:hyperplasia (increased number) and hypertrophy (increased size) of the goblet cells (mucous gland) of the airway, resulting in an increase in secretion of mucus which contributes to the airway obstruction.

Microscopically there is infiltration of the airway walls with inflammatory cells, particularly neutrophils. Inflammation is followed by scarring and remodeling that thickens the walls resulting in narrowing of the small airway. Further progression leads to metaplasia (abnormal change in the tissue) and fibrosis (further thickening and scarring) of the lower airway. The consequence of these changes is a limitation of airflow.