Chronic Obstructive Pulmonary Disease (COPD)

Chronic obstructive pulmonary disease (COPD) is a disease that causes persistent obstruction to airflow.

Chronic bronchitis involves chronic inflammation of the airways. There is also a chronic increase in mucus production. These factors lead to a decrease in the amount of air that can pass through.

Emphysema involves permanent damage to the alveoli. The alveolar walls and pulmonary capillaries become destroyed, and so there less surface area available for gas exchange. Furthermore, the damaged alveoli lose their elasticity, which makes it difficult for them to empty the air out during exhalation, leading to air being trapped inside the alveoli, causing them to be enlarged.

The patient with COPD usually has a combination of both chronic bronchitis and emphysema at the same time.

Causes
COPD is usually caused by many years of smoking cigarettes. Rarely, it can develop in non-smokers, due to long term exposure to pollution and other irritants.

An exacerbation of COPD is usually due to a respiratory infection. This is common in COPD as the usual defense mechanisms of the airways are chronically damaged, and so they are prone to infection. The infection may be viral or bacterial.

Signs and Symptoms
Patients with COPD usually have chronic shortness of breath, especially on exertion, a chronic cough and increased sputum production.

An exacerbation of COPD involves worsening shortness of breath, often with a decrease in oxygen saturation. There may be a worse cough and increased sputum production. There will be a prolonged expiratory phase. 

Purulent sputum and fever may also be present in infective exacerbations of COPD.

Investigations
Oxygen saturation should be continuously monitored in the patients with exacerbation of COPD.

Auscultation may reveal various abnormalities, such as wheeze, rhonchi, crackles and decreased breath sounds.

A chest x-ray is not required to diagnose an exacerbation of COPD. However, sometimes it may be required to exclude other causes of respiratory distress. If a chest x-ray is performed then it often shows hyperexpansion. There may also be other features on the chest x-ray that are suggestive of COPD.

If the exacerbation of COPD is due to infection, then there might be evidence of chest infection on the chest x-ray. Blood tests should also include the white blood cell (WBC) count.

Treatment
Oxygen should be given to any patient that is short of breath. Most exacerbations of COPD only require low oxygen flows (such as 2 to 4 l/min) via nasal cannula to correct hypoxia.

Inhaled beta 2 agonist drugs (such as a Salbutamol nebuliser) should be administered as these cause bronchodilation. Inhaled anticholinergic drugs (such as Ipratropium nebuliser) can also be added if required as these cause airway smooth muscle relaxation. Corticosteroids (such as oral Prednisolone or intravenous Hydrocortisone) are often beneficial to treat exacerbations of COPD.

If the exacerbation is due to a bacterial chest infection, then antibiotics are also required.