Bronchiectasis PDF

# Bronchiectasis Bronchiectasis is the permanent dilation of bronchi and bronchioles caused by destruction of smooth muscle and supporting elastic tissue. It typically results from or is associated with chronic necrotizing infections. It is not a primary disorder, as it always occurs secondary to p...

# Bronchiectasis Bronchiectasis is the permanent dilation of bronchi and bronchioles caused by destruction of smooth muscle and supporting elastic tissue. It typically results from or is associated with chronic necrotizing infections. It is not a primary disorder, as it always occurs secondary to persistent infection or obstruction caused by a variety of conditions. Bronchiectasis gives rise to a characteristic symptom complex dominated by cough and expectoration of copious amounts of purulent sputum. Diagnosis depends on an appropriate history and radiographic demonstration of bronchial dilation. The conditions that most commonly predispose to bronchiectasis include: - **Bronchial obstruction**. Common causes are tumors, foreign bodies, and impaction of mucus. In these conditions, bronchiectasis is localized to the obstructed lung segment. Bronchiectasis may also complicate atopic asthma and chronic bronchitis. - **Congenital or hereditary conditions**, for example: - **Cystic fibrosis**, in which widespread severe bronchiectasis results from obstruction caused by abnormally viscid mucus and secondary infections - **Immunodeficiency states**, particularly immunoglobulin deficiencies, in which localized or diffuse bronchiectasis develops because of recurrent bacterial infections - **Primary ciliary dyskinesia** (also called immotile cilia syndrome), a rare autosomal recessive disorder that is frequently associated with bronchiectasis and sterility in males. It is caused by inherited abnormalities of cilia, thereby impairing mucociliary clearance of the airways, leading to persistent infections - **Necrotizing, or suppurative, pneumonia,** particularly with virulent organisms such as *Staphylococcus aureus* or *Klebsiella spp.*, predisposes affected patients to development of bronchiectasis. Post-tuberculosis bronchiectasis continues to be a significant cause of morbidity in endemic areas. Advanced bronchiectasis has also been reported after SARS-CoV-2 pneumonia. ## Pathogenesis Two intertwined processes contribute to bronchiectasis: obstruction and chronic infection. Either may be the initiator. For example, obstruction caused by a foreign body may impair clearance of secretions, providing a favorable substrate for superimposed infection. The resultant inflammatory damage to the bronchial wall and the accumulating exudate further distend the airways, leading to irreversible dilation. Conversely, a persistent necrotizing infection in the bronchi or bronchioles may lead to poor clearance of secretions, obstruction, and inflammation with peribronchial fibrosis and traction on the bronchi, culminating again in full-blown bronchiectasis. ## Morphology Bronchiectasis usually affects the lower lobes bilaterally, particularly the most vertical air passages. When caused by tumors or aspiration of foreign bodies, it may be sharply localized to a single segment of the lungs. Usually, the most severe involvement is found in the more distal bronchi and bronchioles. The airways may be dilated to as much as four times their usual diameter and can be seen on gross examination almost to the pleural surface. By contrast, in healthy lungs, the bronchioles cannot be followed by eye beyond a point 2 to 3 cm from the pleura. The histologic findings vary with the activity and chronicity of the disease. In severe active cases, an intense acute and chronic inflammatory exudate within the walls of the bronchi and bronchioles leads to desquamation of lining epithelium and extensive areas of ulceration. Typically, sputum cultures reveal mixed flora; the usual organisms include *staphylococci*, *streptococci*, *pneumococci*, enteric organisms, anaerobic and microaerophilic bacteria, and (particularly in children) *Haemophilus influenzae* and *Pseudomonas aeruginosa*. When healing occurs, the lining epithelium may regenerate completely; however, the injury usually cannot be repaired, and abnormal dilation and scarring persist. Fibrosis of the bronchial and bronchiolar walls and peribronchiolar fibrosis develop in more chronic cases. In some instances, the necrosis destroys the bronchial or bronchiolar walls, producing an abscess cavity. ## Clinical Features Bronchiectasis is characterized by severe, persistent cough associated with expectoration of mucopurulent, sometimes foul-smelling, sputum. Other common symptoms include dyspnea, rhinosinusitis, and hemoptysis. Symptoms are often episodic and are precipitated by upper respiratory tract infections or the introduction of new pathogenic agents. Severe widespread bronchiectasis may lead to significant obstructive ventilatory defects, with hypoxemia, hypercapnia, pulmonary hypertension, and cor pulmonale. However, with current treatment, outcomes have improved and severe complications of bronchiectasis, such as brain abscess, amyloidosis, and cor pulmonale, occur less frequently now than in the past. Resection of the affected part of lung is needed in some cases. The image describes a cross section of a lung with bronchiectasis. The affected area is clearly marked on the image with a blue line showing the edges of the dilated bronchi. The bronchi are dilated to almost four times their usual diameter. The image also shows purulent mucus within the bronchi which extends almost to the pleural regions.