MEDAN BUSSINES SITE: Bronchiectasis

Bronchiectasis is an uncommon disease that results in the abnormal and permanent distortion of one or more of the conducting bronchi or airways, most often secondary to an infectious process. First described by Laennec in 1819, later detailed by Sir William Osler in the late 1800s, and further defined by Reid in the 1950s, bronchiectasis has undergone significant changes in regard to its prevalence, etiology, presentation, and treatment.^[1]
Bronchiectasis can be categorized as a chronic obstructive pulmonary lung disease manifested by airways that are inflamed and easily collapsible, resulting in air flow obstruction with shortness of breath, impaired clearance of secretions often with disabling cough, and occasionally hemoptysis. Severe cases can result in progressive impairment with respiratory failure.^{[2, 3]}
Bronchiectasis most often presents as (1) a focal process involving a lobe, segment, or subsegment of the lung or (2) a diffuse process involving both lungs. The former is by far the most common presentation of bronchiectasis, while the latter is most often associated with systemic illnesses, such as cystic fibrosis (CF), sinopulmonary disease, or both. The majority of this article will address non-CF related bronchiectasis.
Diagnosis is usually based on a compatible clinical history of chronic respiratory symptoms, such as a daily cough and viscid sputum production, and characteristic radiographic findings on CT scans, such as bronchial wall thickening and luminal dilatation.

Pathophysiology

Bronchiectasis is an abnormal dilation of the proximal and medium-sized bronchi (>2 mm in diameter) caused by weakening or destruction of the muscular and elastic components of the bronchial walls. Affected areas may show a variety of changes, including transmural inflammation, edema, scarring, and ulceration, among other findings. Distal lung parenchyma may also be damaged secondary to persistent microbial infection and frequent postobstructive pneumonia. Bronchiectasis can be congenital or acquired but is most often the latter.^[1]
Congenital bronchiectasis usually affects infants and children and results from developmental arrest of the bronchial tree. The more commonly acquired forms occur in adults and older children and require an infectious insult, impairment of drainage, airway obstruction, and/or a defect in host defense. The tissue is also damaged in part by the host response of neutrophilic proteases, inflammatory cytokines, nitric oxide, and oxygen radicals. This results in damage to the muscular and elastic components of the bronchial wall. Additionally, peribronchial alveolar tissue may be damaged, resulting in diffuse peribronchial fibrosis.^[4]
The result is abnormal bronchial dilatation with bronchial wall destruction and transmural inflammation. The most important functional finding of altered airway anatomy is severely impaired clearance of secretions from the bronchial tree.
Impaired clearance of secretions causes colonization and infection with pathogenic organisms, contributing to the common purulent expectoration observed in patients with bronchiectasis. The result is further bronchial damage and a vicious cycle of bronchial damage, bronchial dilation, impaired clearance of secretions, recurrent infection, and more bronchial damage.^[5]
In 1950, Reid characterized bronchiectasis as cylindrical, cystic, or varicose in nature.^[6]
Cylindrical bronchiectasis involves diffuse mucosal edema, with resultant bronchi that are dilated minimally but have straight, regular outlines that end squarely and abruptly (see the image below).

Cylindrical bronchiectasis with signet-ring appearance. Note that the luminal airway diameter is greater than the diameter of the adjacent vessel.
Cystic or saccular bronchiectasis has ulceration with bronchial neovascularization and a resultant ballooned appearance that may have air-fluid levels (see the image below).

Cystic and cylindrical bronchiectasis of the right lower lobe on a posterior-anterior chest radiograph.
Varicose bronchiectasis has a bulbous appearance with a dilated bronchus and interspersed sites of relative constriction and, potentially, obstructive scarring. The latter may subsequently result in postobstructive pneumonitis and additional parenchymal damage (see the image below).