Bronchitis - Chronic in Acute Exacerbation

Definition

Chronic bronchitis is defined as chronic productive cough lasting at least 3 months per year for two consecutive years. Acute exacerbation refers to a sudden worsening of symptoms, often triggered by infection or environmental factors.

Epidemiology

• Common in adults, especially smokers or those with long-term exposure to irritants
• Higher prevalence in older adults (>40 years)
• Male predominance historically, though prevalence in females increasing
• Major contributor to chronic obstructive pulmonary disease (COPD) morbidity
• Acute exacerbations are common, leading to hospitalizations

Etiology

• Tobacco smoking (primary risk factor)
• Environmental pollutants and occupational exposure to dust, fumes, or chemicals
• Respiratory infections (viral or bacterial) triggering acute exacerbations
• Genetic susceptibility (e.g., alpha-1 antitrypsin deficiency)
• Comorbidities: asthma, GERD, heart failure
• Airway hyperreactivity and chronic inflammation

Pathophysiology

• Chronic irritation leads to goblet cell hyperplasia and mucus hypersecretion
• Airway inflammation and narrowing contribute to airflow obstruction
• Ciliary dysfunction reduces mucus clearance
• Acute exacerbation occurs due to superimposed infection or trigger
• Hypoxia and hypercapnia may develop in severe cases
• Structural changes: airway wall thickening and small airway fibrosis
• Cycle of infection → inflammation → obstruction perpetuates disease