Bronchiectasis is a disorder characterized by chronic abnormal dilation of the bronchi and destruction of the bronchial walls. It can occur throughout the tracheobronchial tree, or it may be confined to one segment or lobe. It's usually bilateral and involves the basilar segments of the lower lobes.
The disease has three forms: cylindrical (fusiform), varicose, and saccular (cystic). It affects people of both sexes and all ages. With antibiotics available to treat acute respiratory tract infections, the incidence of bronchiectasis has dramatically decreased over the past 20 years. Its incidence is highest among Inuit populations in the northern hemisphere and the Maoris of New Zealand. Bronchiectasis is irreversible.
Causes and pathophysiology
Bronchiectasis results from conditions associated with repeated damage to bronchial walls and with abnormal mucociliary clearance, which causes a breakdown of supporting tissue adjacent to the airways. Such conditions include:
In bronchiectasis, hyperplastic squamous epithelium denuded of cilia replace ulcerated columnar epithelia. Abscess formation occurs, involving all layers of the bronchial walls. This produces inflammatory cells and fibrous tissues. The result is both dilation and narrowing of the airways. Sputum stagnates in the dilated bronchi and leads to secondary infection, characterized by inflammation and leukocytic accumulations. Additional debris collects in and occludes the bronchi. Building pressure from the retained secretions induces mucosal injury. Extensive vascular proliferation of bronchial circulation occurs and produces frequent hemoptysis.
Signs and Symptoms
The most typical symptom is a chronic cough that produces thick, white or green sputum (discharge). The sputum may be foul-smelling and abundant and may contain blood. The individual generally coughs up large amounts of sputum after changing position (for example, after rising from bed). The patient may have recurrent pneumonia, weight loss, and anemia.
Computed tomography scanning is the most useful test for diagnosis. It's sometimes used with high-resolution techniques to better determine anatomic changes.
Bronchography may be ordered for patients who are considering surgery or for those with recurrent or severe hemoptysis. In bronchography, a radiopaque contrast medium outlines the bronchial walls, allowing X-ray images to display the location and extent of disease.
Chest X-rays show peribronchial thickening, atelectatic areas, and scattered cystic changes that suggest bronchiectasis.
Bronchoscopy helps to identify the source of secretions or the bleeding site in hemoptysis.
Sputum culture and a Gram stain identify predominant pathogens.
Complete blood count can reveal anemia and leukocytosis.
Pulmonary function studies detect decreased vital capacity, expiratory flow, and hypoxemia; these tests also help evaluate disease severity, therapeutic effectiveness, and the patient's suitability for surgery.
Depending on the patient and his condition, additional tests may include urinalysis and electrocardiography. (Electrocardiography is normal unless cor pulmonale develops.) If the health care team suspects cystic fibrosis as the underlying cause of bronchiectasis, a sweat electrolyte test may be ordered.
Antibiotic therapy (oral or I.V.) for 7 to 10 days - or until sputum production decreases - is the principal treatment. Bronchodilators and postural drainage and chest percussion help remove secretions if the patient has bronchospasm and thick, tenacious sputum. Occasionally, bronchoscopy may be used to remove secretions. Oxygen therapy may be used for hypoxia. Segmental resection, bronchial artery embolization, or lobectomy may be necessary if pulmonary function is poor.
The only cure for bronchiectasis is surgical remova of the affected lung portion. However, the patient with bronchiectasis affecting both lungs probably won't benefit from surgery.
The risk may be reduced if lung infections are promptly treated.
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