What is bronchiectasis?

Bronchiectasis

Bronchiectasis is a chronic respiratory disease characterized by permanent dilation of bronchi with destruction of elastic and muscular components of their walls, primarily caused by recurrent bacterial colonization and infection leading to progressive airway injury. 1

Pathophysiology

Bronchiectasis develops through a cycle of:

• Initial airway injury
• Inflammation mediated by neutrophils, T lymphocytes, and monocyte-derived cytokines
• Destruction of elastic and muscular components of bronchial walls
• Expansion of airway diameter due to traction from surrounding lung tissue 1

This creates a vicious cycle of bacterial infection, inflammation, and progressive lung damage that must be broken to prevent disease progression 2.

Clinical Presentation

The cardinal symptoms of bronchiectasis include:

• Chronic productive cough (most common symptom)
• Sputum production (often purulent or mucopurulent)
• Recurrent respiratory infections 3

Additional symptoms include:

• Breathlessness
• Rhinosinusitis
• Fatigue
• Hemoptysis
• Thoracic pain 3

Quality of life impairment in bronchiectasis is equivalent to severe COPD, idiopathic pulmonary fibrosis, and other disabling respiratory diseases 3.

Diagnosis

High-resolution CT (HRCT) scanning of the chest is the preferred means of establishing the diagnosis of bronchiectasis, with >90% sensitivity and specificity. 3, 1

Key HRCT findings include:

• Enlarged internal bronchial diameter
• Failure of airways to taper
• Air-fluid levels in dilated airways
• Identification of airways in extreme lung periphery 1

Standard chest X-rays have limited sensitivity and are not recommended for definitive diagnosis 1.

Etiology and Underlying Conditions

With increasing antibiotic use in recent decades, an increasing percentage of patients with bronchiectasis have underlying disorders predisposing them to chronic or recurrent infection 3. These include:

• Cystic fibrosis (CF): Affects upper lobes first, occurs in 3-4% of adult bronchiectasis patients 1
• Primary ciliary dyskinesia (PCD): Predominantly affects lower lobes, found in ≤5% of adult bronchiectasis, associated with situs inversus in Kartagener syndrome 1
• Immunodeficiency disorders: Including antibody deficiency syndromes (7% of cases), hypogammaglobulinemia 1
• Allergic bronchopulmonary aspergillosis (ABPA): Affects central bronchi, found in 4% of bronchiectasis patients 1
• Non-tuberculous mycobacterial (NTM) infection: Particularly MAC, presents with nodular bronchiectasis in middle lobe and lingula 1
• Rheumatoid arthritis: Associated with bronchiectasis in up to 3% of symptomatic patients and 30% on CT 1
• Inflammatory bowel disease: Particularly ulcerative colitis 1
• Aspiration-related: Affects dependent portions of lungs, associated with GERD 1
• Alpha-1 antitrypsin deficiency: Found in <1% of bronchiectasis patients 1
• Congenital abnormalities: Including Williams Campbell syndrome and Mounier Kuhn syndrome 1

Management

Management of bronchiectasis focuses on:

1. Identifying and treating underlying causes

   • Systematic search for underlying causes is essential as it may lead to specific treatments that can slow or halt disease progression 1

2. Improving airway clearance

   • Chest physiotherapy offers modest benefit in increasing sputum volume, though long-term effectiveness is unknown 3
   • Airway clearance techniques and mucoactive drugs 4

3. Controlling infection

   • Antibiotics for exacerbations, with choice depending on likely causative pathogens 3
   • Macrolide therapy to decrease exacerbations 4
   • Inhaled antibiotics for chronic infection management 4

4. Managing symptoms

   • Bronchodilators for symptom relief 4
   • Treatment of complications like hemoptysis

5. Surgical intervention

   • Selected patients with localized idiopathic bronchiectasis causing intolerable symptoms despite maximal medical therapy should be offered surgical treatment 3

Complications and Prognosis

Exacerbations of bronchiectasis are key targets for therapy as they:

• Are major determinants of healthcare costs
• Are associated with increased airways and systemic inflammation
• Contribute to progressive lung damage 3

In severe cases, massive hemoptysis can lead to death 5.

Special Considerations

Bronchiectasis frequently overlaps with other airway diseases:

• 4-72% of patients with severe COPD have radiological bronchiectasis
• 20-30% of patients with severe or uncontrolled asthma have bronchiectasis 6

Co-diagnosis of bronchiectasis with another airway disease is associated with:

• Increased lung inflammation
• Frequent exacerbations
• Worse lung function
• Higher mortality 6

This overlap requires a holistic, pathophysiology-based approach to treatment rather than treating each condition in isolation 6.