11. Bronchiectasis; pulmonary abscess and pulmonary gangrene

BRONCHIECTASIS

This is permanent abnormal dilatation of bronchi caused by chronic airway inflammation and infection.
Causes include post-infective damage, cystic fibrosis, primary ciliary dyskinesia, immunodeficiency, allergic bronchopulmonary aspergillosis, aspiration, obstruction by tumour/foreign body and traction from interstitial lung disease.
The vicious cycle is impaired mucociliary clearance, bacterial colonisation, neutrophilic inflammation, airway wall destruction and further clearance failure.
Cylindrical, varicose and cystic patterns may be described radiologically.

Typical symptoms are chronic productive cough, daily purulent sputum, recurrent chest infections, haemoptysis, dyspnoea and fatigue.
Examination may show coarse crackles, wheeze, clubbing or signs of respiratory failure.
High-resolution CT is the diagnostic imaging test: bronchoarterial ratio enlargement, lack of normal tapering and peripheral airway visibility are characteristic.
Sputum cultures, including mycobacterial cultures when indicated, guide therapy.
Assess lung function, oxygenation, immunoglobulins and cause-specific tests.
Consider bronchoscopy for focal disease or suspected obstruction.

A lung abscess is a localised cavity containing pus and necrotic tissue, commonly following aspiration of anaerobic oral flora or infection distal to obstruction.
Risk factors include impaired consciousness, poor dentition, dysphagia, alcohol misuse, neurological disease and immunosuppression.
Symptoms include fever, night sweats, weight loss, cough with foul sputum and sometimes haemoptysis.
Chest radiograph may show a cavity with an air-fluid level; CT defines size, location and obstruction.
Differential includes cavitating cancer, TB, fungal infection, infected bulla and septic emboli.