Bronchiectasis Overview and Causes

Bronchiectasis

• Bronchiectasis is the permanent widening of the bronchi and bronchioles caused by the destruction of smooth muscle and elastic tissue.
• It's often associated with chronic necrotizing infections.
• It's not a primary disorder but a consequence of other conditions.
• A key symptom is a persistent cough producing copious amounts of purulent sputum.
• Diagnosis relies on medical history and X-rays to show bronchi dilation.

Causes of Bronchiectasis

• Obstruction: Tumors, foreign bodies, and mucus plugs can obstruct the bronchi, leading to localized bronchiectasis in the affected lung segment.
• Infections: Chronic conditions like cystic fibrosis, immunodeficiencies, and certain pneumonia types can cause bronchiectasis.
• Congenital/Hereditary Conditions: Cystic fibrosis, where mucus is abnormally thick, and primary ciliary dyskinesia, a genetic disorder affecting cilia function in the airways, are examples.
• Atopic Asthma and Chronic Bronchitis: These conditions can lead to the development of bronchiectasis.

Pathogenesis

• Bronchiectasis results from a combination of obstruction and persistent infection.
• Obstruction, like by foreign bodies, impairs secretion clearance, creating a breeding ground for infections.
• Necrotizing infections cause damage to the bronchial walls, leading to irreversible dilation.
• Recurring infections and inflammatory responses cause further damage and dilation.

Morphology

• Commonly affects the lower lobes bilaterally, particularly the most vertical air passages.
• Airway dilation can be severe.
• Histologic findings depend on disease activity; active cases are characterized by inflammatory exudate, ulceration, and desquamation of lining epithelium.
• In chronic cases, fibrosis is present.

Clinical Features

• Characterized by persistent, severe coughing and expectoration of mucopurulent sputum, sometimes foul-smelling.
• Other symptoms can include dyspnea, rhinosinusitis, and hemoptysis.
• Episodes are often triggered or exacerbated by upper respiratory infections or exposure to new pathogens.
• Severe bronchiectasis can lead to significant respiratory complications such as hypoxemia, hypercapnia, and cor pulmonale.

Organisms

• Possible infection-causing agents include bacteria (staphylococci, streptococci, pneumococci, enteric organisms, anaerobic and microaerophilic bacteria, Haemophilus influenzae, Pseudomonas aeruginosa)
• Some types of pneumonia can be a contributing factor.