Bronchiectasis

Epidemiology and Etiology

Definition

Bronchiectasis is a chronic disease in which there is permanent damage to the airways, causing abnormal bronchial dilation and mucosal inflammation.

Epidemiology

• Prevalence is estimated to be approximately 350,000–500,000 cases in the United States.
• Age:
  • Occurs at any age
  • Increased incidence with older age
• More common in women

Etiology

• Idiopathic (most common)
• Primary infection:
  • Bacterial:
    • Klebsiella species
    • Staphylococcus aureus
    • Pseudomonas aeruginosa
    • Mycobacterium tuberculosis
    • Mycobacterium avium complex
    • Mycoplasma pneumoniae
  • Viral:
    • Measles virus
    • Pertussis virus
    • Influenza virus
    • Herpes simplex virus
    • Adenovirus
    • Respiratory syncytial virus
  • Fungal:
    • Aspergillus
    • Histoplasma capsulatum
• Bronchial obstruction:
  • Endobronchial tumors
  • Encroachment from hilar lymphadenopathy (right middle lobe syndrome)
  • Foreign body aspiration
  • Mucous plug
• Pneumonitis:
  • Aspiration
  • Inhalation injury
• Congenital disorders:
  • Cystic fibrosis
  • Young syndrome
  • Primary ciliary dyskinesia
  • Alpha-1 antitrypsin (AAT) deficiency
• Anatomic defects:
  • Bronchopulmonary sequestration
  • Congenital cartilage deficiency
  • Tracheobronchomegaly
• Lung disease:
  • Chronic obstructive pulmonary disease
  • Asthma
• Hypersensitivity:
  • Allergic bronchopulmonary aspergillosis (ABPA)
  • Hypersensitivity pneumonitis
• Immunodeficiency states:
  • Hypogammaglobulinemia
  • Complement deficiencies
  • HIV/AIDS
  • Immunosuppressive therapy
• Autoimmune diseases/connective tissue disorders: 
  • Rheumatoid arthritis
  • Sjögren syndrome
  • Systemic lupus erythematosus 
  • Inflammatory bowel disease
  • Sarcoidosis

Pathophysiology

• The development of bronchiectasis typically results from:
  • An infection
  • Impaired mucous drainage
  • Airway obstruction
  • Impaired host defenses
• An inflammatory response occurs → tissue damage to the bronchial walls, including:
  • Smooth muscle
  • Elastic fibers
• Bronchial walls dilate → impairs secretion clearance
• Organisms are able to colonize and cause infection → more bronchial damage and purulent sputum 
• Becomes a continuous cycle of:
  • Bronchial damage
  • Bronchial dilation 
  • Impaired clearance of secretions 
  • Recurrent infection

Clinical Presentation

The signs and symptoms of bronchiectasis will slowly progress over years and are accompanied by periods of acute exacerbation.

Chronic symptoms

• Chronic cough
• Sputum production:
  • Mucopurulent
  • Thick
• Dyspnea
• Pleuritic chest pain
• Wheezing
• Hemoptysis
• Rhinosinusitis

Advanced disease

Patients may develop: 

• Pulmonary hypertension
• Right heart failure
• Wasting and weight loss

Acute exacerbation symptoms

Exacerbations of bronchiectasis are often heralded by the following:

• Increased sputum production over baseline: 
  • Increased viscosity
  • Purulence
  • Foul odor 
• Increased dyspnea and wheezing
• Low-grade fever
• Fatigue and malaise
• Pleuritic chest pain

Physical exam

Nose and throat exam:

• Halitosis
• Nasal polyps

Pulmonary exam:

• Crackles
• Rhonchi
• Wheezing

Evidence of chronic hypoxia:

• Digital clubbing (uncommon)
• Cyanosis
• Plethora (from secondary polycythemia)

Evidence of right heart failure:

• Peripheral edema
• Jugular venous distention
• Hepatomegaly

Diagnosis

Imaging

Bronchiectasis is diagnosed with the use of radiography.

Chest X-ray: 

• Usually the initial test performed
• Only 50% of cases will have abnormal findings.
• Diagnostic findings:
  • Thickening of the airway walls
  • Airway dilation
• Nondiagnostic findings:
  • Linear atelectasis
  • Irregular peripheral opacities from mucous plugs

High-resolution CT (HRCT): 

• More sensitive and specific
• Findings:
  • Airway dilation: 
    • Parallel “tram lines” in a horizontal orientation
    • “Signet-ring” sign: cross-sectional finding of a dilated bronchus that is contiguous with a smaller pulmonary artery
    • Nonuniform dilation (varicose)
    • Cystic
    • Lack of bronchial tapering
  • Mucopurulent plugs with postobstructive air trapping (“tree-in-bud” pattern)
• Distribution:
  • Lower lobes → idiopathic (most cases)
  • Upper lobes → cystic fibrosis
  • Middle and lower lobe → primary ciliary dysfunction

Pulmonary function testing

• ↓ Forced expiratory volume in 1 second (FEV₁)
• ↓ or normal forced vital capacity (FVC)
• ↓ FEV₁/FVC ratio

Supporting evaluation

The evaluation for an underlying etiology may include:

• ↑ Eosinophils → ABPA
• Immunoglobulin testing:
  • Evaluation for hypogammaglobulinemia
  • IgE specific to Aspergillus → ABPA
• Sweat chloride testing and cystic fibrosis transmembrane conductance regulator (CFTR) gene mutation → cystic fibrosis
• AAT level → AAT deficiency
• Autoimmune workup:
  • Rheumatoid factor
  • Antinuclear antibody
  • Antineutrophil cytoplasmic antibody
• Sputum smear and culture for:
  • Bacteria
  • Mycobacteria
  • Fungi

Management

Goals

Bronchiectasis is a chronic condition. Thus, management focuses on:

• Improving symptoms 
• Reducing complications
• Controlling exacerbations
• Reducing morbidity and mortality 
• Managing underlying conditions

General management

• Identify and treat the underlying cause.
• Improve clearance of mucus:
  • Chest physical therapy
  • Deep breathing with forced expiratory maneuvers
  • Humidification
  • Mucolytics are often used in cystic fibrosis patients.
• Reverse airflow obstruction:
  • Bronchodilators:
    • Beta-agonists
    • Anticholinergics
  • Corticosteroid therapy
• Infection treatment: antibiotics
  • Empiric choices: 
    • Amoxicillin–clavulanate
    • Fluoroquinolones (provides coverage for Pseudomonas)
  • Tailored to sputum culture and sensitivity
• Vaccinations:
  • Influenza
  • Pneumococcal pneumonia
• Smoking cessation counseling

Surgical management

Surgery is not usually indicated, but it may be used in specific circumstances:

• Bronchial artery embolization for massive hemoptysis
• Lung resection:
  • Removal of the most severely involved segments of the lung
  • May be pursued for advanced disease or massive hemoptysis
• Lung transplantation is considered for severe bronchiectasis (such as in cystic fibrosis).

Prognosis

• Mortality has improved with the advent of antibiotic therapy. 
• A poorer prognosis is associated with:
  • A cystic fibrosis diagnosis
  • Advanced age
  • Poor functional status
  • Hypoxemia
  • Hypercapnia

Differential Diagnosis

• Chronic obstructive pulmonary disease (COPD): a lung disease characterized by progressive, largely irreversible airflow obstruction: Symptoms include progressive dyspnea and chronic cough. Prolonged expiration, wheezing, or diminished breath sounds may be noted on exam. The diagnosis is confirmed with pulmonary function testing. The imaging findings of bronchiectasis are not generally seen. Management includes smoking cessation, pulmonary rehabilitation, and pharmacotherapy.
• Asthma: a chronic inflammatory condition characterized by reversible obstruction to airflow in the lower airways: Patients present with intermittent or persistent wheezing, coughing, and dyspnea. Diagnosis is usually confirmed with pulmonary function testing showing a reversible obstructive pattern. The imaging findings of bronchiectasis are not generally seen. Management varies based on the severity, and it includes bronchodilators and inhaled corticosteroids for control of inflammation.
• Pneumonia: infection of the lung parenchyma most often caused by bacteria or a virus: Patients present with fever, dyspnea, and a productive cough. Chest X-ray usually shows lobar consolidation. Management usually involves empiric antibiotics, which can be tailored if the causative organism is identified. Antivirals are used when a viral cause is suspected.
• Aspiration pneumonitis: inhalation of either oropharyngeal or gastric contents into the lower airways. This stimulates an inflammatory response, resulting in cough, dyspnea, chest discomfort, and fever. The diagnosis is often clinical and supported with chest X-ray findings of ground-glass opacities in dependent regions. Management is supportive, and patients should be monitored for the development of pneumonia.