Bronchiectasis¶
Chapter 301 | Part 7: Disorders of the Respiratory System
KEY CLINICAL POINTS¶
- Bronchiectasis is irreversible airway dilation, most commonly cylindrical (non-CF) or cystic (CF) in form
- Key etiologies include infection (e.g., Pseudomonas, NTM), obstruction (foreign bodies, tumors), immunodeficiency, and genetic disorders (e.g., CF, Kartagener's syndrome)
- Diagnosis requires radiologic criteria (CT findings: tram tracks, signet-ring sign) and clinical syndrome (persistent cough, sputum production, exacerbations)
- Management includes antibiotic therapy for infections, bronchial hygiene techniques, and anti-inflammatory agents for selected cases
- Complications include hemoptysis, respiratory failure, and progressive lung function decline
1. DEFINITION & OVERVIEW¶
Bronchiectasis refers to irreversible airway dilation involving the lung in focal or diffuse patterns. Classically categorized as cylindrical (most common), varicose, or cystic. This chapter focuses on non-CF bronchiectasis; CF-specific management is detailed in Chapter 302.
Table 301-1 Major Etiologies of Bronchiectasis and Proposed Workup¶
| PATTERN OF LUNG INVOLVEMENT | ETIOLOGY BY CATEGORY (EXAMPLES) | WORKUP |
|---|---|---|
| Focal | Obstruction (foreign body, tumor mass) | Chest imaging (x-ray/CT), bronchoscopy |
| Focal | Infection (bacterial, NTM) | Sputum cultures, bronchoscopy with BAL |
| Focal | Immunodeficiency (hypogammaglobulinemia, HIV) | CBC, immunoglobulin testing, HIV screening |
| Focal | Genetic causes (CF, Kartagener's syndrome) | Sweat chloride test, genetic testing |
| Focal | Autoimmune (rheumatoid arthritis, Sjögren's) | Serologic testing, joint exam |
| Focal | Recurrent aspiration | Swallowing function test |
| Focal | Miscellaneous (yellow nail syndrome, traction bronchiectasis) | Imaging, biopsy |
| Diffuse | Infection (MAC, idiopathic pulmonary fibrosis) | Chest CT, sputum analysis |
| Diffuse | Idiopathic | Exclusion of other causes |
1.1 Clinical Spectrum¶
Diffuse bronchiectasis involves widespread lung fields, often secondary to systemic/infectious disease. Focal involvement may arise from obstruction (tumors, foreign bodies), infection (NTM, Pseudomonas), or congenital causes (immotile cilia syndrome).
1.2 Diagnostic Criteria¶
Consensus guidelines require radiologic criteria (CT findings: inner/outer airway artery ratio ≥ 1.5, lack of airway tapering, visible airways in periphery) and clinical syndrome ( ≥ 2 of: daily cough, daily sputum, history of exacerbations).
2. EPIDEMIOLOGY¶
Prevalence in US has increased; more common in women. Age-related incidence rises. CF-associated bronchiectasis occurs in late adolescence/early adulthood. MAC-related bronchiectasis affects nonsmoking women >50 years. Co-occurrence with COPD/asthma is common. In developing nations, non-CF bronchiectasis with unclear etiology is increasingly reported.
2.1 Demographics¶
More common in women; incidence increases with age. MAC-related cases predominantly affect nonsmoking women >50 years. CF-associated cases peak in late adolescence/early adulthood.
2.2 Risk Factors¶
Immunodeficiency, chronic aspiration, prior tuberculosis, radiation fibrosis, and malnutrition (especially in developing nations) increase risk.
3. ETIOLOGY & PATHOPHYSIOLOGY¶
Infectious causes (bacterial, NTM, fungal) and non-infectious (obstruction, autoimmune, genetic) mechanisms. Pathogenesis involves 'vicious cycle hypothesis' of infection → inflammation → impaired clearance → further damage. Genetic factors (CF, α 1-antitrypsin deficiency) and immune-mediated mechanisms (ABPA, rheumatologic diseases) contribute.
3.1 Infectious Mechanisms¶
Pseudomonas, NTM (MAC most common), and fungal infections (Aspergillus) cause chronic colonization and damage. Immune dysfunction (e.g., hypogammaglobulinemia) predisposes to recurrent infections.
3.2 Non-Infectious Causes¶
Obstruction (foreign bodies, tumors), congenital defects (immotile cilia syndrome), radiation fibrosis, and autoimmune conditions (Sjögren's, rheumatoid arthritis) contribute to airway damage.
3.3 Molecular Pathogenesis¶
Neutrophil elastase damage, impaired mucociliary clearance, and inflammatory mediators (proteases, ROS, cytokines) drive airway destruction. Antiproteases like α 1-antitrypsin mitigate damage.
4. CLINICAL FEATURES¶
Persistent productive cough with thick sputum, crackles/wheezes on auscultation, clubbing. Mild airflow obstruction on spirometry. Acute exacerbations present with increased sputum volume/purulence. Hemoptysis (life-threatening in severe cases) and respiratory failure may occur.
4.1 Symptomatology¶
Chronic cough, sputum production, hemoptysis, clubbing, and fatigue. Acute exacerbations with increased sputum volume and purulence.
4.2 Physical Findings¶
Crackles, wheezes, clubbing. Signs of chronic hypoxia (cyanosis, polycythemia).
5. DIFFERENTIAL DIAGNOSIS¶
COPD, asthma, lung cancer, tuberculosis, interstitial lung disease, and cystic fibrosis. Differentiate based on pattern of lung involvement, sputum characteristics, and response to therapy.
5.1 Key Differentiators¶
Persistent sputum production vs. acute bronchitis; focal vs. diffuse involvement; response to bronchodilators vs. antibiotics.
6. INVESTIGATIONS & DIAGNOSIS¶
Chest imaging (CT preferred) with radiologic criteria. Pulmonary function tests show mild obstruction. Sputum analysis, bronchoscopy, and microbiological testing confirm infection. NTM diagnosis requires ≥ 2 positive cultures or histopathology.
6.1 Imaging¶
Chest CT is gold standard. Findings include tram tracks, signet-ring sign, and tree-in-bud patterns. CT must show ≥ 1 of: inner/outer airway ratio ≥ 1.5, lack of tapering, or visible airways in periphery.
6.2 Laboratory Tests¶
Sputum cultures, sweat chloride test (CF), immunoglobulin levels, and NTM-specific testing. Bronchoalveolar lavage for fungal/NTM detection.
7. MANAGEMENT & TREATMENT¶
Antibiotic therapy for acute exacerbations (7–14 days), suppressive antibiotics for recurrent infections, bronchial hygiene (hypertonic saline, chest physiotherapy), and anti-inflammatory agents for selected cases (e.g., ABPA). Lung transplantation for advanced disease.
7.1 Antibiotic Therapy¶
Acute exacerbations: cover Pseudomonas and Haemophilus (e.g., ceftazidime/aztreonam). NTM requires prolonged regimens (macrolide + rifampin/ethambutol).
7.2 Bronchial Hygiene¶
Hypertonic saline, postural drainage, oscillatory PEP devices, and pulmonary rehabilitation. Dornase alfa is used in CF but not non-CF bronchiectasis.
7.3 Anti-Inflammatory Agents¶
Oral corticosteroids for ABPA or autoimmune-associated cases. Long-term macrolides (azithromycin) may reduce exacerbations in non-CF bronchiectasis.
8. PROGNOSIS & COMPLICATIONS¶
Progressive lung function decline (FEV loss: 50–55 mL/year in non-CF vs. 20–30 mL/year in controls). Complications include hemoptysis, respiratory failure, and recurrent infections. Macrolide resistance and NTM emergence are risks with long-term therapy.
8.1 Complications¶
Massive hemoptysis (requires bronchial artery embolization/surgery), respiratory failure, and progressive lung function decline. NTM infections complicate treatment.
9. SPECIAL CONSIDERATIONS¶
Pregnancy: monitor for exacerbations; avoid certain antibiotics. Pediatrics: focus on aspiration prevention. Elderly: manage comorbidities. NTM requires specialized treatment regimens.
9.1 Pregnancy¶
Avoid fluoroquinolones; use safe antibiotics. Monitor for worsening symptoms.
9.2 NTM Management¶
MAC treatment: macrolide + rifampin/ethambutol. Avoid long-term macrolides in NTM-positive patients due to resistance risks.
10. KEY POINTS & CLINICAL PEARLS¶
- Bronchiectasis diagnosis requires CT findings + clinical criteria
- NTM infection requires ≥ 2 positive cultures or histopathology
- Long-term macrolides may reduce exacerbations but risk resistance
- Bronchial hygiene is critical for secretion clearance
- Hemoptysis management includes bronchial artery embolization
- Dornase alfa is CF-specific; avoid in non-CF bronchiectasis