Approach Considerations
Bronchiectasis results from recurrent or persistent respiratory inflections or inflammation. The evaluation for the etiology and co-morbidities are guided by the history and physical examination. Identifying the etiology has management implications and should follow an algorithmic approach.. European guidelines recommend a minimal panel of tests that comprises the following: (1) high resolution chest CT, (2) sweat test, (3) spirometry, (4) complete blood cell count, (5) immunologlobulin levels and specific antibodies to vaccine antigens, and (6) lower airway bacteriology via sputum culture or bronchoscopic alveolar lavage.
Imaging Studies
Because bronchiectasis is defined as an abnormal dilatation of airways, the diagnosis depends on radiographically or anatomically visualizing the typical changes. In patients with suspected bronchiectasis, a high-resolution CT (HRCT) scan is the diagnostic procedure of choice. Where available, multi-detector (MDCT) with HRCT is considered the gold standard.
Chest Radiography
Obtain a routine posteroanterior and lateral chest radiograph. A dilated airway, with thickened airway walls can be noted. When seen laterally, the bronchiectatic airway has been described as tram tracks. However, normal radiograph findings do not rule out bronchiectasis. Risk factors for bronchiectasis on chest radiography include atelectasis and persistent lobar abnormalities.
A posteroanterior chest radiograph of a child with bronchiectasis due to chronic aspiration is shown below.
Posteroanterior chest radiograph of a child with bronchiectasis due to chronic aspiration.
Computed Tomography
The diagnosis of bronchiectasis is usually established using high-resolution CT (HRCT) scanning, which has a sensitivity and specificity of more than 90%. The gold standard in Europe, Australia and New Zealand is a multidetector chest computed tomography (MDCT) scan with high resolution CT scan which provides a continuous image and improves sensitivity to over 95%. [28, 29] The key feature on HRCT scanning is an enlarged internal bronchial diameter with bronchi that appear larger than the accompanying artery (an increased broncho-arterial ratio), called the signet sign. European guidelines define an abnormal broncho-arterial ratio in pediatric patients to be greater than 0.8. [28] Other HRCT scan findings include the failure of the larger airways to taper while progressing to the lung periphery, air fluid levels in the dilated airways, and the identification of airways in the extreme lung periphery.
The most common and consistent radiographic findings on high resolution CT scan of the chest in a patient with bronchiectasis as found by Smith et al include: enlarged internal bronchial diameter relative to the adjacent artery, the signet ring sign, lack of bronchial tapering while progressing towards the lung periphery, bronchi seen at the lung periphery, bronchial wall thickening or mucous plugging or impaction, mosaic perfusion defects, and air trapping on expiration. [30]
Other nonspecific signs of bronchiectasis on high resolution CT scan include air fluid levels in distended bronchi.
Radiographic findings including distribution have been used to define severity of disease. [31, 32] Brconchiectasis progresses from cylindrical to varicose then cystic (or saccular) changes as the broncho-arterial ratio increases. As severity increases reversibility decreases.
In settings where a high resolution CT scans with pediatric specific protocols regarding radiation exposure is not always readily available, a presumptive diagnosis of bronchiectasis can be made by relevant clinical history and physical exam findings.
A CT scan of the chest of a child with bronchiectasis due to chronic aspiration is shown below.
Gastroesophageal Reflux Disease Assessment
Evaluate patients suspected of having bronchiectasis for gastroesophageal reflux disease, especially infants and young children. Studies may include barium esophagraphy, gastric scintiscanning, or intraesophageal pH or impedance monitoring. Suspicion of poor oromotor coordination should lead to a swallow function study.
Flexible Bronchoscopy
Flexible bronchoscopy may help assess the caliber and appearance of the airways and provide bronchoalveolar lavage fluid for evidence of chronic aspiration or infection. Significant numbers of lipid-laden macrophages or significant amounts of pepsin or amylase may suggest recurrent aspiration.
A study evaluated the value of flexible bronchoscopy and bronchoalveolar lavage (BAL) in indigenous children as part of the workup at the first diagnosis of bronchiectasis. [33] BAL eosinophilia was found in 34% of the children; of these, 42% were found to have positive serology to Strongyloides, which was not known beforehand. BAL microbiology led to a change in antibiotic therapy in 9%. These data suggest a larger role for bronchoscopy in the diagnosis of pediatric bronchiectasis.
Bronchoscopy can also help identify foreign bodies or underlying structural anomalies, while providing a macroscopic view of the airways. If a retained foreign body is strongly suspected, rigid rather than flexible bronchoscopy should be considered.
Bronchography
In the past, fluoroscopically guided selective bronchography, using water-soluble contrast media and performed by an experienced bronchoscopist, provided excellent anatomic definition. This study has been virtually eliminated by CT imaging.
Histologic Findings
Examination of the bronchoalveolar fluid reveals inflammatory cells. Hemosiderin-laden macrophages generally suggest nonacute bleeding. Lipid-laden macrophages suggest chronic aspiration but may also be observed in other forms of severe airway disease associated with inflammation. Therefore there remains some controversy over the usefulness of lipid-laden alveolar macrophages given its high sensitivity but low specificity as an indicator of aspiration, as they are often found in acute or chronic lung disease not related to aspiration and even healthy persons.
Laboratory Studies
Laboratory evaluation of bronchiectasis may include the following tests:
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Sweat chloride
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With underlying asthma or cystic fibrosis (CF), evaluation for allergic bronchopulmonary aspergillosis should include immunoglobulin E (IgE) and serum precipitins for Aspergillus species , sputum culture for fungus, and an aspergillus skin test
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Complete blood cell count
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Serum immunoglobulin G (IgG) with IgG subclasses, immunoglobulin M (IgM), and IgA
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Speech pathologist assessment for identification of possible dysphagia with aspiration
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HIV test
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Sputum culture or deep oropharyngeal swab in younger children
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Spirometry for children older than 6 years of age
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Ciliary biopsy
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Antinuclear antibody and rheumatoid factor
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Vaccine antigens
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Flexible fiberoptic bronchoscopy
Obviously, not every patient with bronchiectasis requires each of the above studies. The history and physical examination should help guide the clinician to choose the appropriate studies.
Spirometry
Often spirometry may be normal early in the course of patients with bronchiectasis. As the disease progresses, it is obstructive in the earlier stages and becomes mixed obstructive and restrictive disease process later in the disease. Other lung function abnormalities include high residual lung volume, lower aerobic capacity.
Spirometry can be used to monitor disease control with acute drops in function and worsening obstructive pattern associated with acute exacerbations.
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Posteroanterior chest radiograph of a child with bronchiectasis due to chronic aspiration.
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CT scan of the chest of a child with bronchiectasis due to chronic aspiration.
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Chest radiograph of a child with severe adenoviral pneumonia as an infant. The child has persistent symptoms of cough, congestion, and wheezing.
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Bronchoscopic bronchogram of the left lower lobe on a patient with history of adenoviral pneumonia, demonstrating cylindrical and varicose types of bronchiectasis.
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Bronchoscopic bronchogram of the right upper lobe of a patient with a history of adenoviral pneumonia, demonstrating saccular bronchiectasis.
