Chronic Obstructive Lung Disease - Introduction

Introduction

Chronic obstructive pulmonary disease (COPD) is a condition in which there is limited airflow in the lungs. The disease develops and worsens over time. COPD is not reversible, but therapy can slow its progress.

Although patients can breathe in normally, changes in the small airways cause the walls to narrow during expiration, making it hard to breathe out. In many patients with COPD, the small sacs where oxygen and carbon dioxide are exchanged are destroyed, gradually starving the body of oxygen.

COPD is associated with a set of breathing-related symptoms:

• Being out of breath, at first when doing physical activities, but as lung function deteriorates, also at rest
• Chronic cough
• Spitting or coughing mucus (phlegm)

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The ability to exhale (breathe out) gets worse over time.

The two major diseases in this category are emphysema and chronic bronchitis, both covered in this report. The third, less common disease, is obstructive bronchiolitis, an inflammatory condition of the small airways. Asthma shares some of the same symptoms, but is a very different disease. People can have asthma and COPD at the same time. [See In-Depth Report #4: Asthma in adults.]

Because smoking is a common cause of both emphysema and chronic bronchitis, these conditions often develop together and frequently require similar treatments and approaches. When chronic bronchitis occurs together with emphysema, it is often difficult for a physician to distinguish between the two diseases.

Emphysema

Emphysema is a disease in which the alveoli, grape-like clusters of air sacs at the end of the smallest airways (the bronchioles) are destroyed. It generally takes the following course:

• The walls of the alveoli become inflamed and damaged. Over time they lose the ability to stretch and shrink (elasticity), and pockets of dead air (called bullae) form in the injured areas.
• The pockets interfere with the normal working of the lungs by narrowing the airways, trapping air, and making breathing out more difficult.
• The ability to breathe in is not affected. Until the late stages of the disease, oxygen and carbon dioxide levels remain normal.