Permanent dilation of the bronchi and bronchioles due to chronic infection

Aetiology

• The main organisms patients are infected by include: Haemophilius Influenzae, Pseudomonas aeruginosa, Streptococcus Pneumoniae, Staphylococcus aureus

Underlying causes

• Cystic fibrosis - most common cause in developed countries
• Bronchial narrowing/obstruction - COPD, aspiration, tumours, ABPA
• Lung infection (e.g. pneumonia, TB), especially severe/chronic infections
• Immunodeficiency
• Many other causes, 50% are idiopathic

Pathophysiology

1. Excessive inflammatory response to infection/obstruction leading to fibrosis
2. Airway dilates as surrounding scar tissue contracts
3. The dilation allows for the stasis of mucus → chronic infection
4. In summary: cycles of bronchial inflammation, mucus plugging and progressive airway destruction leads to irreversible and abnormal dilation of the bronchial tree

Clinical features

Symptoms

• Chronic productive cough
• Fever and malaise
• Haemoptysis (flecks)

Signs