Bronchiectatic disease

Bronchiectatic disease is a chronic acquired, and in some cases congenital disease, characterized by a local suppurative process (purulent endobronchitis) in irreversibly altered (dilated, deformed) and functionally defective bronchi, mainly in the lower parts of the lungs.

Bronchiectasis is dilation and destruction of the large airways caused by chronic infection and inflammation. Common causes are cystic fibrosis, immune disorders, and infections, although some cases are probably idiosyncratic. Symptoms are chronic cough and purulent sputum production; some patients may have fever and dyspnea. Diagnosis is based on history and imaging, usually high-resolution CT, although standard chest radiography may be diagnostic. Treatment and prevention of exacerbations include antibiotics, drainage of secretions, and monitoring for complications such as superinfection and hemoptysis. Underlying causes of bronchiectasis should be treated when possible.

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Causes bronchiectatic disease

Diffuse bronchiectasis occurs in patients with genetic, immune, or anatomical defects that cause airway damage. Cystic fibrosis is the most common cause; less common genetic causes include ciliary dyskinesia and severe alpha1-antitrypsin deficiency. Hypogammaglobulinemia and immunodeficiencies may also cause diffuse damage to the bronchial tree, as can rare abnormalities of airway structure (eg, tracheobronchomegaly [Mounier-Kuhn syndrome], cartilage deficiency [Williams-Campbell syndrome]). Diffuse bronchiectasis is a rare complication of more common disorders such as rheumatoid arthritis, Sjögren's syndrome, and allergic bronchopulmonary aspergillosis, probably by multiple mechanisms.

Focal bronchiectasis develops with untreated pneumonia or obstruction (eg, due to foreign bodies and tumors, external compression, or changes in anatomy after lobar resection).

All of these conditions impair airway clearance mechanisms and immune defenses, resulting in an inability to clear secretions and predisposing to infection and chronic inflammation. As a result of frequent infection, typically with Haemophilus influenzae (35%), Pseudomonas aeruginosa (31%), Moraxella catarrhalis (20%), Staphylococcus aureus (14%), and Streptococcus pneumoniae (13%), the airways fill with viscous mucous secretions containing inflammatory mediators and pathogens and slowly dilate, scar, and distort. Histologically, the bronchial walls are thickened by edema, inflammation, and neovascularization. Destruction of the surrounding interstitium and alveoli causes fibrosis, emphysema, or both.

Non-tuberculous mycobacteria can cause bronchodilation and also colonize the lungs of patients with bronchiectasis that developed due to other causes.

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Symptoms bronchiectatic disease

The main symptoms of bronchiectasis are chronic cough, which can produce a large volume of thick, viscous, purulent sputum. Shortness of breath and wheezing are common. Hemoptysis, which can be massive, occurs due to the formation of new vessels in the respiratory tract from the bronchial (but not pulmonary) arteries. Subfebrile temperature occurs during exacerbations of the disease, during which the intensity of the cough and the volume of sputum increase. Chronic bronchitis can resemble bronchiectasis in its clinical manifestations, but bronchiectasis is distinguished by a more abundant release of purulent sputum daily and typical changes on CT.

Typical symptoms of bronchiectasis include bad breath and abnormal breathing sounds, including crackling and wheezing. The tips of the fingers may also be thickened.

Symptoms usually develop insidiously and recur more frequently, gradually worsening over the years. In severe cases, hypoxemia, pulmonary hypertension, and right ventricular failure may occur.

Superinfection with multidrug-resistant organisms, including nontuberculous mycobacteria, should be considered as a possible underlying cause of symptoms in patients with recurrent exacerbations or deteriorating lung function tests.

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Forms

The independence of bronchiectatic disease as a separate nosological form can currently be considered proven by the following circumstances. The infectious and inflammatory process in bronchiectatic disease occurs mainly within the bronchial tree, and not in the pulmonary parenchyma. In addition, convincing confirmation is the operation, in which the removal of bronchiectasis leads to the recovery of patients.

Along with bronchiectasis as an independent nosological entity, the pathomorphological substrate of which is primary bronchiectasis (bronchiectasis), secondary bronchiectasis (bronchiectasis) are distinguished, which are a complication or manifestation of another disease. Most often, secondary bronchiectasis occurs with lung abscess, pulmonary tuberculosis, chronic pneumonia. With secondary bronchiectasis, there are usually pathological changes in the respiratory section of the lungs, which distinguishes secondary bronchiectasis from bronchiectasis.

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Diagnostics bronchiectatic disease

Diagnosis is based on history, physical examination, and radiographic examination, beginning with chest radiography. Radiographic findings suggestive of bronchiectasis include irregular scattered opacities caused by mucus plugs, honeycombing, and rings and tramlines caused by thickened, dilated bronchi located perpendicular or longitudinal to the x-ray beam, respectively. Radiographic patterns may vary depending on the underlying disease: bronchiectasis in cystic fibrosis occurs primarily in the upper lobes, whereas that due to other causes is more diffuse or predominantly in the lower lobes. High-resolution CT is the imaging modality of choice for detecting bronchiectasis. The study is nearly 100% sensitive and specific. CT typically shows bronchial dilations and cysts (sometimes grape-like), scattered mucus plugs, and airways that are more than 1.5 times larger in diameter than adjacent blood vessels. Dilated medium-sized bronchi may extend almost to the pleura. Atelectasis, consolidation, and decreased vascularity are additional nonspecific changes. The differential diagnosis of dilated airways includes bronchitis and “traction bronchiectasis,” which occurs when pulmonary fibrosis stretches the airways and holds them open.

Pulmonary function tests should be performed to document baseline function and subsequently monitor disease progression. Bronchiectasis is associated with airflow limitation (reduced forced expiratory volumes in 1 s [FEV1], forced vital capacity [FVC], and FEV/FVC); FEV may improve in response to beta-agonist bronchodilators. Lung volumes and diffusing capacity for carbon monoxide (DLCo) may be decreased.

Investigations aimed at diagnosing the underlying cause include sputum examination with staining and culture for bacteria, mycobacteria (Mycobacterium avium complex and Mycobacterium tuberculosis), and fungal (Aspergillus) infections. Mycobacterial superinfection is diagnosed by repeatedly culturing atypical mycobacteria (with a high colony count) and finding granulomas on biopsy with parallel radiographic evidence of disease. Additional studies may include sweat chloride testing to diagnose cystic fibrosis, which should be performed even in older patients; rheumatoid factor and other serologic tests to exclude systemic connective tissue diseases; immunoglobulins, including IgG subclasses, to document certain immunodeficiencies; Aspergillus precipitins, IgE, and eosinophilia tests to exclude allergic bronchopulmonary aspergillosis and alpha1-antitrypsin to document deficiency. When clinical manifestations suggest ciliary dyskinesia (in the presence of sinus disease and middle and lower lobe bronchiectasis with or without infertility), a biopsy of the nasal or bronchial epithelium should be performed and the biopsy examined by transmission electron microscopy for abnormal ciliary structure. A less invasive alternative is sperm motility testing. The diagnosis of ciliary dyskinesia should be made with caution by an experienced clinician trained in specialized techniques, since nonspecific structural defects may be present in up to 10% of cilia in healthy patients and in patients with lung disease; infection may cause transient dyskinesia. Ciliary ultrastructure may be normal in patients with primary ciliary dyskinesia syndromes characterized by abnormal ciliary function.

Bronchoscopy is indicated when anatomical abnormalities or external compression are suspected.

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Treatment bronchiectatic disease

Treatment includes prevention of exacerbations, treatment of underlying causes, intensive treatment of exacerbations, and monitoring for the development of complications.

There is no consensus on the best approach to preventing or limiting exacerbations. Daily prophylaxis with oral antibiotics (eg, ciprofloxacin 500 mg twice daily) and, in patients with cystic fibrosis colonized with P. aeruginosa, inhaled tobramycin (300 mg twice daily for 1 month on and 1 month off) has been suggested. In addition, aerosolized gentamicin (40 mg twice daily) may be effective in patients with diffuse bronchiectasis due to other causes.

As with any chronic lung disease, patients are recommended to be vaccinated against influenza and pneumococcal disease annually.

Various techniques may promote secretion clearance, including postural drainage and chest percussion, positive expiratory pressure devices, intrapulmonary percussive ventilators, pneumatic vests, and autogenic drainage (a breathing technique that promotes the movement of secretions from the peripheral to the central airways). A mucolytic (rhDNa3a) has been shown to be clinically effective in patients with cystic fibrosis. Patients should try breathing techniques with the guidance of a respiratory therapist and select and use the technique that is most effective; no other method of choice is justified.

Additional treatment for bronchiectasis depends on the underlying cause. Allergic bronchopulmonary aspergillosis is treated with glucocorticoids and possibly in combination with azolide antifungals. Patients with immunoglobulin deficiencies should receive replacement therapy. Patients with alpha1-antitrypsin deficiency should also receive replacement therapy.

Treatment of exacerbations of bronchiectasis is with antibiotics that are effective against H. influenzae, P. aeruginosa, M. catarrhalis. aureus, and S. pneumoniae (eg, ciprofloxacin 400 mg intravenously 2–3 times, then 500 mg orally 2 times daily or levofloxacin 750–500 mg intravenously, then orally once daily for 7–14 days). Azithromycin 500 mg 3 times weekly is effective in bronchiectasis due to cystic fibrosis, but it is unclear whether macrolides are effective in other nosological entities. Antibiotic therapy should be accompanied by an enhanced effect on sputum clearance from the respiratory tract.

Management of acute complications includes treatment of mycobacterial superinfection and bleeding.

An empirical regimen for the treatment of M. avium complex may include the simultaneous administration of several (at least three) drugs: clarithromycin orally 500 mg twice daily or azithromycin 250-500 mg once daily; rifampin 600 mg orally once daily or rifabutin 300 mg orally once daily; and ethambutol 25 mg/kg orally once daily (2 months), then continue at 15 mg/kg once daily. All drugs should be taken long-term (up to 12 months), until sputum cultures are negative. Surgical resection is rarely necessary, but may be considered when antibiotic therapy is ineffective and bronchiectasis is fairly localized.

Massive bleeding is usually treated with bronchial artery embolization along with antibiotic therapy for exacerbations.

Prevention

Prevention of bronchiectasis requires timely detection and treatment of the underlying causes. Unfortunately, most patients seek medical help only when the disease bronchiectasis has fully developed.

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Forecast

Overall, 80% of patients with bronchiectasis who do not have further deterioration of lung function due to isolated bronchiectasis have a good prognosis. However, patients with cystic fibrosis have a median life expectancy of 32 years, and most patients experience recurrent exacerbations.

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