Updated: Mar 4, 2009
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 in the Pathophysiology section, below), but it usually results from necrotizing bacterial infections, such as infections caused by the Staphylococcus or Klebsiella species or Bordetella pertussis. Diagnosis is based on a clinical history of daily viscid sputum production and characteristic computed tomography (CT) scanning findings (see CT Scan).
By definition, bronchiectasis demonstrates localized, irreversible dilatation of bronchi > 2 mm in diameter that results from destruction of the muscular and elastic components of bronchial walls. Damage to these 2 bronchial wall components is caused by an infectious organism and also by the inflammatory cytokines, nitric oxide, and neutrophilic proteases released by the host's immune 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 involved bronchi are not only dilated but also inflamed and easily collapsible, resulting in airflow obstruction and impaired clearance of secretions.
The most important functional finding of altered airway anatomy is severely impaired clearance of secretions from the bronchial tree. This altered airway anatomy causes colonization and infection with pathogenic organisms, contributing to the common purulent expectoration observed in patients who have bronchiectasis. The result is a cycle of bronchial damage, bronchial dilatation, impaired clearance of secretions, recurrent infection, and more bronchial damage.
Diseases associated with bronchiectasis are as follows:
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.
Bronchiectasis is an important cause of morbidity in underdeveloped countries. Its incidence has diminished in developed countries, but it is still an important cause of morbidity, especially in children.
No racial predilection exists. There is a 4-fold higher incidence in American Indians and Alaskan Native Americans.1
No sex predilection exists.
In patients with cystic fibrosis, bronchiectasis usually appears in childhood, but its onset may be delayed to adulthood.2
Bronchiectasis usually involves bronchi of medium size (>2 mm diameter). The proximal (main, lower, and segmental) bronchi are less affected, because they contain more cartilage than the distal bronchi and because they are more resistant to dilation. However, in patients with allergic bronchopulmonary aspergillosis and cystic fibrosis, the proximal bronchi are typically involved.
Although bronchiectasis caused by bacterial and viral infections usually affects the lower pulmonary 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 those with immunodeficiency states.
In advanced cases of bronchiectasis, dilated, medium-sized bronchi extend close to the pleura, without side branches and with few 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.3
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:
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.4
Hemoptysis is common and may occur in as many as 50% of patients.5 Episodic hemoptysis with little to no sputum production (dry bronchiectasis) is usually a sequela of tuberculosis. However, 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 accompanies 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 reported in 37-51% of patients with bronchiectasis.6 Edwards and colleagues found that children with digital clubbing and chest deformity showed significantly higher scores for the extent of their bronchiectasis, bronchial wall dilatation and thickness, and overall changes based on CT scanning scores. Cyanosis, plethora, wasting, weight loss, nasal polyps, and signs of chronic sinusitis may be present. In patients with advanced disease, signs of cor pulmonale may be detected.
Chest radiography is usually the first imaging examination, but the findings are often nonspecific and the images may appear normal. HRCT scanning has become the imaging modality of choice for demonstrating or ruling out bronchiectasis and its extent (see Image 2, Image 4, Image 7, Images 10-12). HRCT scanning also helps clinicians evaluate the status of the surrounding lung tissue and exclude other lesions such as neoplasms.7
Laboratory testing may be helpful:
Bronchoscopy is not helpful in diagnosing bronchiectasis, but it may be used to identify underlying abnormalities, such as tumors and foreign bodies.
Chest radiographs may be negative in patients with minor to moderate disease. Many abnormal radiographic findings may be nonspecific, and confirmation using HRCT scanning may be required (see Radiograph).
Bronchography is rarely indicated (see Radiograph) because it is invasive and is associated with allergic reactions to the contrast material. Bronchography also carries the risk of acute bronchoconstriction.
HRCT scanning is the diagnostic modality of choice and has few limitations (see CT Scan).
| Aspergillosis, Thoracic | Empyema |
| Aspiration Pneumonia | Idiopathic Pulmonary Fibrosis |
| Asthma | Lung, Postprimary Tuberculosis |
| Bronchiolitis Obliterans Organizing
Pneumonia | Pneumonia, Typical Bacterial |
| Cystic Fibrosis, Thoracic | |
| Emphysema |
Lung, abscess
a 1 -Antitrypsin deficiency (see Alpha1-Antitrypsin Deficiency)
Radiography
Chest radiography helps to identify serious disease, and it was once the standard imaging modality. However, the radiographs may depict no abnormalities, or the findings may be nonspecific in patients with less-severe disease.9
Various abnormal radiographic findings have been described as follows:
Bronchography
Introduced in 1922, bronchography was the investigation of choice until the introduction of HRCT scanning in the mid 1980s. Currently, bronchography is rarely used. Bronchography is performed by instilling contrast material via a catheter or bronchoscope under fluoroscopic control and plain radiographic imaging. The procedure is unpleasant for the patient and is also associated with temporary impairment of ventilation, as well as allergic and foreign body reactions to the contrast medium. In addition, interpretation of bronchographic images is difficult, owing to underfilling and retained secretions.
The accuracy of plain radiographic findings in the diagnosis of bronchiectasis is unknown, because the findings are variable and nonspecific and depend on the severity and extent of the bronchiectasis. However, 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.
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.
The HRCT imaging technique consists of obtaining 1- to 2-mm collimation scans at 10-mm intervals through the chest with a window level (WL) of –700 Hounsfield units (HU) and a window width (WW) of –1000 HU. The right middle lobe and lingular bronchi cross obliquely and are not optimally depicted on axial HRCT scans; as a result, a gantry angulation of 20° may be required.10,11,12,13
HRCT scan findings include the following:
Other findings include the following:
High-resolution CT (HRCT) scanning has a sensitivity of 96% and a specificity of 93%,8 as compared with bronchography, the previous criterion standard.
Bronchial measurements may vary with the use of different WLs and WWs.
Some patients without bronchiectasis have a 1.49:1 bronchus-to-artery ratio; however, the ratio is reliable only if it is greater than 1.5. If the ratio is less than 1.5, other signs, such as bronchial wall thickening and lack of tapering, should be present for the diagnosis of bronchiectasis.
The variability of the bronchus-to-artery ratio at high altitudes and in patients with pulmonary hypertension may result in an overdiagnosis because of vasoconstriction in these conditions.
Bronchial wall thickening is optimally seen with a WW of –1000 HU and a WL of –700 HU; higher WL and other WW readings are associated with artifactual wall thickening. This finding is not specific and is also seen in patients with asthma and in those who smoke.
In patients with consolidation, dilated bronchi may not be seen. Cardiac and respiratory artifacts may obscure the results or mimic subtle bronchiectasis in the left lower lobe. Rarely, histiocytosis X and cavitating pulmonary masses mimic cystic bronchiectasis. Traction bronchiectasis occurs in patients with interstitial fibrosis and results from fibrous tethering of the bronchial wall. Traction bronchiectasis is not a true bronchial disorder.
Hemoptysis is symptomatic of a potentially life-threatening condition and warrants urgent and comprehensive evaluation of the lung parenchyma, airways, and thoracic vasculature.
Multidetector-row CT angiography permits noninvasive, rapid, and accurate assessment of the cause and consequences of hemorrhage into the airways and helps guide subsequent management. The combined use of thin-section axial scans and more complex reformatted images allows clear depiction of the origins and trajectories of abnormally dilated systemic arteries that may be the source of hemorrhage and that may require embolization.
Bronchiectasis, chronic bronchitis, lung malignancy, tuberculosis, and chronic fungal infection are some of the most common underlying causes of hemoptysis and are easily detected with CT angiography.
Bronchial arterial embolization offers an alternative to surgery in select patients with massive or recurrent hemoptysis caused by bronchiectasis, particularly in those patients with cystic fibrosis. In most patients, the hemoptysis originates in the systemic bronchial arteries rather than from the pulmonary arteries.
Selective arteriography of the bronchial arteries is performed to locate the source of the bleeding. In bronchiectasis, bleeding is usually a result of enlarged, dilated bronchial arteries, which are occluded by embolization with use of particulate material larger than the smaller arterioles.
Spinal cord infarction is a potential complication of bronchial artery embolization and arises because the bronchial arteries may communicate with arteries that supply the spinal cord.
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bronchiectasis, bronchial tree disease, pulmonary disease, abnormal dilatation of bronchi, pulmonary infections, cystic fibrosis, Young syndrome, primary ciliary dyskinesia, allergic bronchopulmonary aspergillosis, hypogammaglobulinemia, bronchopulmonary sequestration, Williams-Campbell syndrome, Mounier-Kuhn syndrome, Swyer-James syndrome, yellow nail syndrome, rheumatoid arthritis, Sjögren syndrome
Isaac Hassan, MB, ChB, FRCR, DMRD, Former Senior Consultant Radiologist, Department of Radiology, St Bernard's Hospital, Gibraltar
Isaac Hassan, MB, ChB, FRCR, DMRD is a member of the following medical societies: American Roentgen Ray Society and Royal College of Radiologists
Disclosure: Nothing to disclose.
Judith K Amorosa, MD, FACR, Clinical Professor and Program Director, Department of Radiology, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School; Consulting Staff, Department of Radiology, Robert Wood Johnson University Hospital
Judith K Amorosa, MD, FACR is a member of the following medical societies: American College of Radiology, American Roentgen Ray Society, Association of University Radiologists, Radiological Society of North America, and Society of Thoracic Radiology
Disclosure: Nothing to disclose.
Bernard D Coombs, MB, ChB, PhD, Consulting Staff, Department of Specialist Rehabilitation Services, Hutt Valley District Health Board, New Zealand
Disclosure: Nothing to disclose.
John D Newell, Jr, MD, FACR, FCCP, FASER, Co-Director of Thoracic Imaging, UCDHSC; Director of Lung Imaging Center, Professor of Radiology and Professor of Medicine, Department of Radiology, University of Colorado Health Sciences Center, National Jewish Medical and Research Center; Univ. Colorado Hospital
John D Newell, Jr, MD, FACR, FCCP, FASER is a member of the following medical societies: American College of Chest Physicians, American College of Radiology, American Roentgen Ray Society, American Thoracic Society, Association of University Radiologists, Radiological Society of North America, and Society of Thoracic Radiology
Disclosure: Siemens Medical Grant/research funds Consulting; Forevision Technologies Ownership interest Consulting; Vida Corporation Ownership interest Board membership; TeraRecon Grant/research funds Consulting; eMedicine Honoraria Consulting
Robert M Krasny, MD, Consulting Staff, Department of Radiology, The Angeles Clinic and Research Institute
Robert M Krasny, MD is a member of the following medical societies: American Roentgen Ray Society and Radiological Society of North America
Disclosure: Nothing to disclose.
Eugene C Lin, MD, Consulting Radiologist, Virginia Mason Medical Center; Clinical Assistant Professor of Radiology, University of Washington School of Medicine
Eugene C Lin, MD is a member of the following medical societies: American College of Nuclear Medicine, American College of Radiology, Radiological Society of North America, and Society of Nuclear Medicine
Disclosure: Nothing to disclose.
Related eMedicine topics
Bronchiectasis (from Pulmonology)
Bronchiectasis (from Pediatrics: General Medicine)
Pneumonia, Bacterial
Pneumonia, Viral
Chronic Obstructive Pulmonary Disease
Clinical guidelines
Chronic Cough due to Bronchiectasis: ACCP Evidence-Based Clinical Practice Guidelines
Pulmonary Rehabilitation: Joint ACCP/AACVPR Evidence-Based Clinical Practice Guidelines
Clinical studies
Efficacy of Budesonide-Formoterol in Bronchiectasis
Airway Clearance in Bronchiectasis: is Non-Invasive Ventilation a Useful Adjunct in Moderate to Severe Disease?
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