Description

Bronchiectasis is an irreversible syndrome with symptoms of chronic productive cough, recurrent exacerbations, and characteristic findings on cross-sectional imaging of bronchial wall dilation and thickening.

Epidemiology

Etiology and Pathophysiology

• Bronchiectasis often arises as a complication of inherited or acquired disease states but may arise as an isolated diagnosis.
• Vicious cycle hypothesis (1):
  • An initial pulmonary insult causes airway inflammation, dysfunction, and structural disease.
  • Dysfunctional airways are further impaired in their ability to clear infections.
  • A pattern of lung damage/inflammation and progressive airway dysfunction is established, leading to clinical decline.
• Neutrophil extracellular traps (NETs) levels and neutrophil elastase activity correlate with disease activity and may serve as potential therapeutic targets (1).

Risk Factors

• Severe lower respiratory tract infection
• Tuberculosis (TB), non-TB mycobacterium, pertussis, and viruses, including adenovirus and measles
• Certain systemic diseases such as connective tissue diseases and inflammatory bowel disease

General Prevention

• Routine immunization against respiratory infections (pertussis, measles, Haemophilus influenzae type B, influenza, and Streptococcus pneumonia)
• Genetic counseling for patients with inheritable conditions which predispose to bronchiectasis who wish to conceive
• Encourage and support smoking cessation in all patients who smoke.

Commonly Associated Conditions

• Many cases are idiopathic, and bronchiectasis may be an isolated pulmonary diagnosis.
• Acquired conditions associated with bronchiectasis include recurrent lower respiratory tract infections (bacterial pneumonia, TB, allergic bronchopulmonary aspergillosis [ABPA]), GERD, conditions of airflow obstruction (asthma/chronic obstructive pulmonary disease [COPD], obstructing airway mass), connective tissue disorders, and chronic aspiration.
• Inherited conditions associated with bronchiectasis include CF, primary ciliary dyskinesia, congenital airway abnormalities (tracheobronchomalacia, tracheobronchomegaly, familial congenital bronchiectasis [Williams-Campbell syndrome]), α1-antitrypsin deficiency, and primary immunodeficient conditions (X-linked agammaglobulinemia, common variable immune deficiency, hyper-IgE syndrome).