Bronchiectasis - Suppurative lung disorders

Bronchiectasis

Definition

Bronchiectasis is a condition characterised by purulent sputum production with cystic dilation of the bronchi.

Aetiology

In developed countries, cystic fibrosis is the most common cause, tuberculosis and post-childhood infections are also common.

1. Changes in the normal drainage of bronchial secretions:

Airway obstruction such as by a tumour or foreign body.

The mucus may not drain if it is excessively thick as in cystic fibrosis.

Conditions affecting cilia such as ciliary dyskinesia and Kartagener’s syndrome (genetic syndrome associated with dextrocardia and situs inversus).

2. Infections causing damage to the bronchial walls:

Childhood respiratory infection in the developing lung, e.g. measles, whooping cough and pneumonia.

Persistent infections such as tuberculosis, allergic bronchopulmonary aspergillosis.

Immunodeficiency states resulting in recurrent infections.

Pathophysiology

Impairment of the mucociliary transport mechanism leads to recurrent infections, which leads to further accumulation of mucus. Bronchial walls become inflamed, thickened and permanently dilated. The lower lobes of the lungs tend to be most affected because of gravitational pooling of secretions.

Clinical features

In mild cases sputum production only occurs post-infection. More severely affected patients have chronic halitosis, a cough with copious thick sputum, recurrent fevers and episodes of pneumonia. Patients may be dyspnoeic, clubbed and cyanosed. Haemoptysis may occur due to friable granulation tissue and can be massive. Coarse crackles and sometimes wheeze (due to airflow limitation) are heard over affected areas.

Macroscopy

Large dilated air spaces are seen extending out to the lung periphery.

Microscopy

Chronic inflammation in the wall of the abnormal bronchi with replacement of the epithelium with inflammatory granulation tissue, which bleeds. There may be squamous metaplasia of the bronchial mucosa.

Complications

Pneumonia.

Pneumothorax, empyema.

Chronic cases may lead to respiratory failure and cor pulmonale.

Chronic suppuration causes abscess formation, haematogenous spread of infection (formation of cerebral abscesses) and development of amyloidosis.

Investigations

Chest X-ray may be normal or may show the dilated thick walled bronchi.

High resolution CT scans are diagnostic showing the dilated bronchi with thickened walls and adjacent artery forming the typical signet ring appearance.

Sputum culture is necessary to treat infections. The most common organisms are Staph. aureus, Pseu-domonas aeruginosa, H. influenzae and anaerobes.

Serum immunoglobulins, sweat test, cilial motility studies where indicated.

Management

The aim is to prevent chronic sepsis and reduce acute infections.

1.     1 Non-pharmacological: Postural drainage is crucial and requires training by physiotherapists. Patients are taught to tip and hold themselves in the correct positions several times a day.

2.     Pharmacological:

Antibiotics are given for acute infections and exacerbations.

Bronchodilator therapy may be useful if there is airflow obstruction.

3.     If hypoxic long term oxygen therapy may delay the onset of cor pulmonale.

4.     Surgery may be needed for massive haemoptysis.

Prognosis

Variable depending on cause and severity.