Understanding Chronic Lung Disease
Chronic Lung Disease, also known as Chronic Obstructive Pulmonary Disease (COPD) or Chronic Obstructive Airway Disease (COAD), is a term used to refer to chronic respiratory diseases such as chronic bronchitis and emphysema. It is a progressive disease that causes difficulty in breathing. The term "progressive" here means that the disease worsens over time. Under these conditions, the airways become narrowed and limited flow of air to and from the lungs causes a shortness of breath. In chronic bronchitis, there is persistent inflammation of the airways (bronchi) in the lungs. In emphysema, the bronchioles (smaller airways) and alveoli (air sacs) of the lungs are damaged. Most patients with chronic lung disease have a mix of both emphysema and bronchitis. Unlike Asthma, this condition is unfortunately irreversible and usually worsens over time.
Figure A shows the location of the lungs and airways in a healthy body. The inset image shows a detailed cross-section of the bronchioles and alveoli. Figure B shows lungs damaged by chronic lung disease. The inset image shows a detailed cross-section of the damaged bronchioles and alveolar walls.
Image source: National Heart, Lung and Blood Institute
How common is Chronic Lung Disease?
It is currently the seventh leading cause of death in Singapore. About 2,000 hospitalisations a year are due to lung disease and the numbers are steadily rising.
A 'wet' cough with phlegm (sputum) is usually the first symptom to develop. In the early stages, this cough is intermittent (on and off). As the condition worsens, the cough gets more persistent and becomes what is commonly referred to as a 'smoker's cough'.
- Excessive sputum
The damaged airways produce more mucus than healthy airways. This contributes to the formation of excessive sputum, resulting in a 'wet' cough.
- Breathlessness (shortness of breath)
During the initial stage, a patient will experience this symptom only after physical exertion.
Smoking is the main culprit in most cases as it damages the lining of the airways from the lungs and causes the lining to become inflamed. Air pollution including polluted work conditions can also play a part in worsening the patients’ conditions.
When you consult your doctor, he or she will:
- Determine if you have the symptoms of chronic lung disease (i.e. cough, excessive sputum and breathlessness)
- Check if you are at risk of developing chronic lung disease (e.g. due to cigarette smoking and exposure to certain environmental toxins)
If you experience any of the above symptoms or belong to the high risk group, you are most likely to be suffering from chronic lung disease.
- Pulmonary (Lung) Function Testing
This is the most important tool used to confirm chronic lung disease. It can detect the disease in the early stages when the patient may not show any symptoms. One of the tests requires a patient to breathe into a spirometer machine. The readings from the spirometer will then confirm the presence of chronic lung disease and assess its severity. This test is also useful in monitoring the patient's progress over time and to review the effectiveness of treatment.
- Chest X-ray
A chest X-ray is useful to rule out other conditions which may seem like chronic lung disease. It is also useful in detecting the complications of chronic lung disease. However, just a chest X-ray alone cannot confirm the diagnosis of chronic lung disease.