What is bronchiectasis and its management for a patient with chronic cough and sputum production?

Bronchiectasis: Definition and Clinical Overview

Bronchiectasis is a chronic respiratory disease characterized by permanent, irreversible dilation of the bronchi with destruction of the elastic and muscular components of their bronchial walls, typically resulting from acute or chronic infection, and presenting clinically with chronic productive cough and recurrent respiratory infections. 1, 2

Structural and Pathophysiologic Features

Permanent airway damage is the defining characteristic that distinguishes bronchiectasis from reversible conditions:

• The bronchial walls undergo destruction of their elastic and muscular components, leading to abnormal and permanent dilation that cannot be reversed once established 1, 2
• A vicious cycle develops involving chronic bronchial infection, inflammation, impaired mucociliary clearance, and progressive structural lung damage 2, 3
• Neutrophilic inflammation is the hallmark pathologic process, with neutrophil elastase and collagenase directly destroying bronchial wall components 2
• The contractile force of surrounding lung tissue exerts traction on the damaged airways, further expanding their diameter 1, 3
• Increased bronchial arterial proliferation and arteriovenous malformations develop, predisposing patients to recurrent hemoptysis 1, 3

Cardinal Clinical Manifestations

Chronic productive cough is the most consistent and defining symptom:

• Daily mucopurulent or purulent sputum production is typical, though some patients may have nonproductive cough 1, 4
• Recurrent respiratory infections occur due to impaired bacterial clearance 2, 5
• Hemoptysis develops from abnormal bronchial vasculature 4
• Progressive dyspnea worsens as airflow obstruction advances 4
• Physical examination may reveal rhonchi, crackles, clubbing, or may be entirely normal 1

Diagnostic Confirmation

High-resolution CT (HRCT) scanning is essential and the preferred diagnostic method, as bronchiectasis is defined by radiographic visualization of abnormal airway dilation:

• HRCT has sensitivity and specificity exceeding 90% and has replaced bronchography as the gold standard 1, 3
• The key diagnostic feature is the "signet ring sign" where bronchi appear larger than their accompanying pulmonary artery 1
• Additional HRCT findings include failure of larger airways to taper while progressing to the lung periphery and air-fluid levels in dilated airways 3
• Routine chest radiographs may show bronchiectasis but are insufficient for definitive diagnosis 1

Underlying Etiologies Requiring Investigation

An increasing proportion of patients have identifiable underlying disorders that must be evaluated:

Diffuse Distribution Causes:

• Cystic fibrosis (most common identifiable cause in the United States and Europe, occurring in 1 per 2,000-3,000 live births) 3
• Immunodeficiency states: common variable immunodeficiency, hypogammaglobulinemia (especially IgG and IgG subclasses), HIV infection 1, 3
• Primary ciliary dyskinesia (genetic disorder affecting ciliary structure and mucociliary clearance) 1, 3
• Allergic bronchopulmonary aspergillosis (causes central cystic bronchiectasis) 1, 3
• Chronic Mycobacterium avium complex infection (particularly in white women in their seventh or eighth decade) 1, 3
• Connective tissue diseases: rheumatoid arthritis (2-5% of cases), inflammatory bowel disease 3
• Alpha-1-antitrypsin deficiency 3

Focal Distribution Causes:

• Bronchial obstruction from foreign body, tumor, broncholith, or compression by peribronchial lymph nodes 1, 3
• Previous severe pneumonia or tuberculosis 3, 4
• Post-pneumonia focal damage 3

Focal bronchiectasis is particularly important to recognize because it may be amenable to bronchoscopic intervention or surgical resection 1

Clinical Significance and Disease Progression

Bronchiectasis is a progressive condition with substantial morbidity and mortality implications:

• Quality of life impairment is equivalent to severe COPD 2
• Exacerbations are associated with increased inflammation, accelerated lung function decline, and higher mortality 2
• Mortality risk increases significantly, with up to 30% mortality at 1-year follow-up after an exacerbation, particularly when COPD coexists 2
• Frequent exacerbations (≥3 per year) and chronic Pseudomonas aeruginosa colonization indicate severe disease 4
• Without treatment, the condition can progress to respiratory failure 2

Management Principles

Treatment aims to prevent exacerbations, reduce symptoms, improve quality of life, and halt disease progression:

Airway Clearance:

• Regular airway clearance techniques are essential components of management and offer modest benefit in increasing sputum volume 2, 3
• Chest physiotherapy should be implemented, though long-term effectiveness data are limited 1

Antimicrobial Therapy:

• Exacerbations require antibiotics, with agent selection based on likely causative pathogens (commonly Haemophilus influenzae, Staphylococcus aureus, Streptococcus pneumoniae, and Pseudomonas aeruginosa) 1, 3
• Long-term antibiotic therapy (oral or inhaled) may be required for pathogen eradication and exacerbation prevention 2
• For Mycobacterium avium complex infection, first-line therapy consists of a macrolide, ethambutol, and a rifamycin 3

Adjunctive Therapies:

• Bronchodilators address airflow obstruction 2
• Pulmonary rehabilitation improves exercise capacity 2
• Mucolytics such as acetylcysteine are indicated as adjuvant therapy for abnormal, viscid, or inspissated mucous secretions in bronchiectasis 6

Surgical Intervention:

• Selected patients with localized idiopathic bronchiectasis causing intolerable symptoms despite maximal medical therapy should be offered surgical treatment 1, 3

Etiology-Specific Treatment:

• For allergic bronchopulmonary aspergillosis, corticosteroid treatment may be beneficial 3
• Treatment should target the underlying cause when identified 3

Critical Clinical Pitfalls

Early diagnosis and intervention are crucial because bronchial wall dilatation may be reversible in early disease 2, 3. However, chronic productive cough occurs far more commonly in chronic bronchitis, asthma, upper airway cough syndrome, and gastroesophageal reflux disease than in bronchiectasis—in one prospective study, bronchiectasis accounted for only 4% of patients with expectoration of >30 mL of sputum per day 1. Therefore, maintain high clinical suspicion but confirm diagnosis with HRCT before attributing symptoms to bronchiectasis.