Bronchiectasis
Bronchiectasis Causes
Both congenital and acquired causes of bronchiectasis are known. Kartagener syndrome, which affects the mobility of cilia in the lungs, helps in the development of the disease. Another common genetic cause is cystic fibrosis, in which a few patients develop severe localized bronchiectasis. Young's syndrome, which is clinically similar to cystic fibrosis, is thought to significantly contribute to the progression of bronchiectasis. This is because of the occurrence of chronic, sinopulmonary infections. Patients with alpha 1-antitrypsin deficiency have also been found to be particularly susceptible to bronchiectasis, for unknown reasons. Other less-common congenital causes include primary immunodeficiencies, mainly because of the weakened or nonexistent immune system response to severe, recurrent infections that commonly affect the lung.
Bronchiectasis Definition
Bronchiectasis is a disease that results to localized, irreversible dilatation of part of the bronchial tree. Involved bronchi are dilated, inflamed, and easily collapsible, leading to airflow obstruction and impaired clearance of secretions. Bronchiectasis is associated with a wide range of disorders, but it usually arises from necrotizing bacterial infections, such as infections caused by the Staphylococcus or Klebsiella species or Bordetella pertussis.
Bronchiectasis Diagnosis
The diagnosis of bronchiectasis is based on the review of clinical history and distinct patterns in high-resolution CT scan findings. Such patterns include "tree-in-bud" abnormalities and cysts that have definable borders. In a small study, CT findings of bronchiectasis and multiple small nodules were reported to have a sensitivity of 80%, specificity of 87%, and accuracy of 80% for the detection of bronchiectasis. Bronchiectasis may also be diagnosed without CT scan confirmation if clinical history clearly shows frequent, respiratory infections, as well confirmation of an underlying problem via blood work and sputum culture samples.
Bronchiectasis Pathogenesis
Dilation of the bronchial walls leads to airflow obstruction and impaired clearance of secretions because the dilated areas disrupt normal air pressure in the bronchial tubes, causing sputum to pool inside the dilated areas instead of being pushed upward. The pooled sputum provides an environment conducive to the growth of infectious pathogens, and these areas of the lungs become very vulnerable to infection. The more infections that the lungs undergo, the more damaged the lung tissue and alveoli become. When this happens, the bronchial tubes result in becoming more inelastic and dilated, creating a self-perpetuating cycle of further damage to the lungs. There are three types of brochiectasis, differing by level of severity. Fusiform (cylindrical) bronchiectasis (which is the most common type) refers to mildly inflamed bronchi that fail to taper distally. In varicose bronchiectasis, the bronchial walls appear beaded, due to areas of dilation being mixed with areas of constriction. Saccular (cystic) bronchiectasis is marked by severe and irreversible ballooning of the bronchi peripherally, with or without air-fluid levels. Chronic productive cough is prominent, happening in up to 90% of patients with bronchiectasis. Sputum is produced on a daily basis in 76% of individuals with the disease.