Background: Bronchiectasis is defined as localized irreversible dilatation of part of the bronchial tree. Involved bronchi are dilated, inflamed, and easily collapsible, resulting in airflow obstruction and impaired clearance of secretions. Bronchiectasis is associated with a wide range of disorders (see Diseases associated with bronchiectasis), but it usually results from necrotizing bacterial infections, such as infections caused by Staphylococcus or Klebsiella species or Bordetella pertussis. Diagnosis is based on a clinical history of daily viscid sputum production and characteristic CT findings.

Pathophysiology: Bronchiectasis is defined as the abnormal dilatation of the proximal medium-sized bronchi (>2 mm in diameter) caused by destruction of the muscular and elastic components of bronchial walls. Damage to the muscular and elastic components of the bronchial wall is caused by the infectious organism and also by the inflammatory cytokines, nitric oxide, and neutrophilic proteases released in the host response to the organism. Additionally, peribronchial alveolar tissue may be damaged, resulting in diffuse peribronchial fibrosis. The result is abnormal bronchial dilatation with bronchial wall destruction and transmural inflammation.

The most important functional finding of altered airway anatomy is severely impaired clearance of secretions from the bronchial tree. This causes colonization and infection with pathogenic organisms, contributing to the common purulent expectoration observed in patients with bronchiectasis. The result is further bronchial damage and a cycle of bronchial damage, bronchial dilation, impaired clearance of secretions, recurrent infection, and more bronchial damage.

Diseases associated with bronchiectasis are as follows:

• Infection: Typical organisms include Klebsiella species, Staphylococcus aureus, Mycobacterium tuberculosis, Mycoplasma pneumoniae, nontuberculous mycobacteria, Mycobacterium avium-intracellulare complex, measles, pertussis, influenza, respiratory syncytial virus, herpes simplex virus, and certain types of adenovirus.

   

• Bronchial obstruction: Obstruction occurs as a result of endobronchial tumors, broncholithiasis, bronchial stenosis resulting from infections, encroachment of hilar lymph nodes, and foreign body aspiration.

   

• Cystic fibrosis

   

• Young syndrome

   

• Primary ciliary dyskinesia

   

• Allergic bronchopulmonary aspergillosis

   

• Immunodeficiency states: The most common congenital conditions involve B-lymphocyte functions, specifically hypogammaglobulinemia. An aggressive form of bronchiectasis has been described in patients with AIDS.

   

• Congenital anatomic defects

   

  • Bronchopulmonary sequestration

     

  • Williams-Campbell syndrome (congenital cartilage deficiency)

     

  • Mounier-Kuhn syndrome (tracheobronchomegaly)

     

  • Swyer-James syndrome (unilateral hyperlucent lung)

     

  • Yellow nail syndrome

   

• a₁-Antitrypsin deficiency

   

• Lung and bone marrow transplants

   

• Rheumatoid arthritis and Sjögren syndrome

   

• Traction bronchiectasis associated with pulmonary fibrosis

Frequency:

• In the US: The incidence of bronchiectasis declined after the introduction of immunizations (pertussis) and antibiotics. The exact overall incidence is not known because the symptoms are not specific, and minor forms often remain undiagnosed.

  The prevalence is highest among persons in lower socioeconomic groups.

• Internationally: Bronchiectasis is an important cause of morbidity in less-developed countries.

Mortality/Morbidity:

• Mortality is related to progressive respiratory failure and cor pulmonale rather than to uncontrolled infection. Hemoptysis is common but rarely causes death.

• Complications include recurrent pneumonia, empyema, pneumothorax, and lung abscess. Amyloidosis and metastatic abscesses, common causes of morbidity and mortality in the pre-antibiotic era, are now uncommon.

Race: No racial predilection exists. A 4-fold higher incidence occurs in American Indians and in Alaskan Native Americans.

Sex: No sex predilection exists.

Age: In patients with cystic fibrosis, bronchiectasis usually appears in childhood, but its onset may be delayed to adulthood.

Anatomy: Bronchiectasis usually involves bronchi of medium size (2 mm in diameter). The proximal (main, lower, and segmental) bronchi are less affected because they contain more cartilage and because they are more resistant to dilation. However, the proximal bronchi typically are involved in patients with allergic bronchopulmonary aspergillosis and cystic fibrosis.

Although bronchiectasis due to bacterial and viral infections typically affects the lower lobes, the upper lobes are more frequently affected in patients with allergic bronchopulmonary aspergillosis and tuberculosis. Bronchiectasis is more diffuse in patients with cystic fibrosis and immunodeficiency states.

In advanced cases, dilated medium-sized bronchi extend close to the pleura, with no side branches and little normal surrounding lung parenchyma. Focal destruction of part of the bronchial wall, increased mucus secretion and retention, and peribronchial fibrosis occur. The surrounding lung shows volume loss, fibrosis, emphysema, and nodular inflammatory foci.

In 1950, Reid classified bronchiectasis as cylindrical, cystic, or varicose.

• In cylindrical bronchiectasis, bronchi have a uniform caliber, they do not taper, and they have parallel walls.

   

• Cystic or saccular bronchiectasis is a severe form of bronchiectasis. Involved bronchi are cystlike in appearance and extend to the pleural surface. Air-fluid levels are commonly present.

   

• Varicose bronchiectasis is relatively uncommon. Bronchi have a beaded appearance with a dilated bronchus and interspersed sites of relative narrowing.

Clinical Details:

History

The classic triad of symptoms (chronic cough, excess purulent sputum production, repeated infections) is seen only in the most severely affected patients. Total daily sputum production has been used to characterize severity of bronchiectasis. Production of less than 10 mL/d is defined as mild bronchiectasis, 10-150 mL/d is defined as moderate bronchiectasis, and more than 150 mL/d is defined as severe bronchiectasis.

Many patients have only mild or intermittent symptoms. Some patients with mild forms of bronchiectasis, as revealed on high-resolution computed tomography (HRCT) scans, may have no symptoms.

Hemoptysis is common and may occur in as many as 50% of patients. Episodic hemoptysis with little-to-no sputum production (dry bronchiectasis) is usually a sequela of tuberculosis. Massive hemoptysis may occur. Bleeding usually originates in dilated bronchial arteries, which contain blood at systemic (rather than pulmonary) pressures.

Less-specific symptoms include dyspnea, pleuritic chest pain, wheezing, fever, weakness, and weight loss. Significant airway obstruction may occur as a result of the bronchitis, bronchiolitis, or emphysema that frequently accompany bronchiectasis. Repeated bronchial infection and pneumonia are common.

Physical examination

Findings are nonspecific and may be attributed to other conditions. On auscultation, crackles, rhonchi, wheezing, and inspiratory squeaks may be detected. Digital clubbing is rare (5%). Cyanosis, plethora, wasting, weight loss, nasal polyps, and signs of chronic sinusitis may be present. Signs of cor pulmonale may be detected in patients with advanced disease.

Preferred Examination: Chest radiography is usually the first imaging examination, but the findings are often nonspecific and the images may appear normal. Bronchography has been the classic and, until HRCT, the only imaging method to demonstrate bronchiectasis. It was performed by instilling an iodine-based contrast material via a catheter or bronchoscope. Bronchography is rarely if ever performed today. HRCT is the diagnostic modality of choice and has replaced bronchography. HRCT is noninvasive and has a sensitivity of 96% and a specificity of 93%.

Laboratory testing may be helpful.

• Results of sputum culture and analysis may reinforce diagnosis of bronchiectasis and add significant information regarding potential etiologies.

   

• Complete blood counts are often abnormal in patients with bronchiectasis.

   

• Quantitative immunoglobulin levels, including levels of immunoglobulin G (IgG) subclasses, immunoglobulin M (IgM), and immunoglobulin A (IgA), are used to exclude hypogammaglobulinemia.

   

• Quantitative a₁-antitrypsin levels are used to exclude deficiency.

   

• Pilocarpine iontophoresis (sweat testing) is used to detect cystic fibrosis.

   

• Pulmonary function test results may be normal or abnormal. They are useful in making a functional assessment of the patient. The most common abnormality is an obstructive airway defect.

Bronchoscopy is not helpful in diagnosing bronchiectasis, but it may be used to identify underlying abnormalities, such as tumors and foreign bodies.

Limitations of Techniques: Chest radiographs may be negative in patients with minor-to-moderate disease. Many abnormal radiographic findings may be nonspecific, and confirmation using HRCT may be required (see X-ray).

Bronchography is invasive and is associated with allergic reactions to the contrast material and carries the risk of acute bronchoconstriction; bronchography is rarely indicated (see X-ray).

HRCT is the diagnostic modality of choice and has few limitations (see CAT Scan).

DIFFERENTIALS

Aspergillosis, Thoracic
Aspiration Pneumonia
Asthma
Bronchiolitis Obliterans Organizing Pneumonia
Cystic Fibrosis, Thoracic
Emphysema
Empyema
Idiopathic Pulmonary Fibrosis
Lung, Postprimary Tuberculosis
Pneumonia, Typical Bacterial

Other Problems to be Considered:

Lung, abscess
a₁-Antitrypsin deficiency

X-RAY

Findings:

Radiography

Chest radiography helps in identifying serious disease, and it once was the standard imaging modality. However, radiographs may depict no abnormalities, or the findings may be nonspecific in patients with less-severe disease.

Various abnormal radiograph findings have been described as follows:

• Parallel line opacities (tram tracks) due to thickened dilated bronchi

   

• Ring opacities or cystic spaces as large as 2 cm in diameter due to cystic bronchiectasis (see Images 1-2), sometimes with air-fluid levels

   

• Tubular opacities due to dilated fluid-filled bronchi (see Images 3-4)

   

• Increased size and loss of definition of pulmonary vessels in affected areas due to peribronchial fibrosis (see Image 6)

   

• Crowding of pulmonary vascular markings due to the associated loss of volume, usually caused by mucous obstruction of peripheral bronchi (see Image 5, Image 7)

   

• Oligemia due to reduction in pulmonary artery perfusion (severe disease)

   

• Signs of compensatory hyperinflation of the unaffected lung (see Image 1)

Bronchography

Introduced in 1922, bronchography was the investigation of choice until the introduction of HRCT in the mid 1980s. It was performed by instilling contrast material via a catheter or bronchoscope under fluoroscopic control and plain radiographic imaging. Bronchography was an unpleasant procedure for the patient and associated with temporary impairment of ventilation and allergic and foreign body reactions to the contrast medium. Interpretation of bronchographic images was difficult, owing to underfilling and retained secretions. Currently, bronchography is rarely used.

Degree of Confidence: The accuracy of plain radiographic findings in the diagnosis of bronchiectasis is unknown. Radiographic findings are variable and nonspecific and depend on the severity and extent of the bronchiectasis. Good correlation exists between the severity of disease as seen on plain images and HRCT scans. Chest radiographic findings may be normal or nonspecific in patients with less-severe disease.

False Positives/Negatives: Many plain radiographic findings are nonspecific and may be seen in patients with idiopathic pulmonary fibrosis, sarcoidosis, histiocytosis X, rheumatoid lung, and other chronic interstitial lung disorders.