What is Bronchiectasis?
Bronchiectasis is a chronic respiratory disease characterized by permanent, irreversible dilation of the bronchi with destruction of the elastic and muscular components of their walls, typically resulting from acute or chronic infection. 1, 2
Core Pathophysiology
The disease involves a vicious cycle of chronic bronchial infection, inflammation, impaired mucociliary clearance, and progressive structural lung damage. 2 This cycle perpetuates itself as:
- Neutrophilic inflammation is the hallmark feature, with neutrophil elastase and collagenase directly destroying bronchial wall components 2
- Impaired mucociliary clearance leads to mucus stasis and bacterial colonization 2
- The contractile force of surrounding lung tissue exerts traction on weakened airways, expanding their diameter 3
- Increased bronchial arterial proliferation and arteriovenous malformations develop, predisposing to recurrent hemoptysis 3
Clinical Presentation
The cardinal symptom is chronic productive cough with recurrent respiratory infections. 1, 2 Additional features include:
- Chronic sputum production (often viscid and copious) 4, 5
- Recurrent respiratory infections 2, 6
- Hemoptysis (from abnormal vascular proliferation) 2, 3
- Digital clubbing in some cases 2
- Breathlessness due to airflow obstruction, impaired gas transfer, and exercise deconditioning 2
Diagnostic Approach
High-resolution CT (HRCT) scanning is the diagnostic procedure of choice, with sensitivity and specificity exceeding 90%. 3, 7 The diagnosis requires both:
- Radiological confirmation showing permanent bronchial dilation on CT scan 2
- Clinical symptoms of cough, sputum production, and recurrent infections 2
Key HRCT features include enlarged internal bronchial diameter, failure of larger airways to taper toward the lung periphery, and air-fluid levels in dilated airways. 3, 7
Common Underlying Causes
With increased antibiotic use in childhood infections, an increasing proportion of patients now have identifiable underlying disorders: 1
- Cystic fibrosis (most common in US/Europe, 1 per 2,000-3,000 live births) 3, 7
- Primary ciliary dyskinesia (genetic disorder affecting ciliary function) 3, 7
- Immunodeficiencies (common variable immunodeficiency, hypogammaglobulinemia, HIV) 1, 3
- Allergic bronchopulmonary aspergillosis (causes central cystic bronchiectasis) 1, 3, 7
- Chronic Mycobacterium avium complex infection (particularly in older white women) 1, 3, 7
- Post-infectious damage (prior severe pneumonia or tuberculosis) 3
- Connective tissue disorders (rheumatoid arthritis, Ehlers-Danlos, Marfan syndrome) 3
- Bronchial obstruction (foreign bodies, tumors, broncholithiasis) 3
Clinical Significance and Prognosis
Bronchiectasis is a progressive condition that can lead to respiratory failure if untreated, with quality of life impairment equivalent to severe COPD. 2 Critical prognostic factors include:
- Exacerbations are associated with increased inflammation, accelerated lung function decline, and higher mortality 2
- Mortality risk reaches up to 30% at 1-year follow-up after an exacerbation, particularly when COPD coexists 2
- Excessive neutrophilic inflammation correlates with increased exacerbation frequency and rapid lung function decline through elastin degradation 2
Management Principles
Treatment aims to prevent exacerbations, reduce symptoms, improve quality of life, and halt disease progression. 2 Core strategies include:
- Long-term antibiotic therapy (oral or inhaled) for pathogen eradication and exacerbation prevention 2
- Regular airway clearance techniques as essential components of management 2, 3
- Bronchodilators to address airflow obstruction 2
- Pulmonary rehabilitation to improve exercise capacity 2
- Antibiotics for exacerbations based on likely causative pathogens 1, 3
- Surgical resection for selected patients with localized disease causing intolerable symptoms despite maximal medical therapy 1, 3
Early diagnosis and intervention are critical, as bronchial wall dilatation may be reversible in early disease. 2, 3, 7