Because chronic obstructive pulmonary disease (COPD) refers to several types of lung diseases, the symptoms can vary from patient to patient. But there are several symptoms that commonly occur in COPD patients.

• Chronic bronchitis
• Shortness of breath with exercise
• Shortness of breath with everyday activities
• Frequent chest infections or bronchitis
• Coughing with lots of mucus
• Wheezing

What Is Chronic Bronchitis?

The bronchi are air passages connecting the windpipe (trachea) with the sacs of the lung (alveoli), where oxygen is taken up by the blood. Bronchitis is an inflammation of the bronchi, or the lining of the bronchial tube, causing excessive mucus production and swelling of the bronchial walls. When the bronchi are inflamed and/or infected, less air is able to flow to and from the lungs.

Many people suffer a brief attack of acute bronchitis (with fever, coughing, and spitting) when they have a severe cold. Chronic bronchitis, however, is defined by the presence of a mucus-producing cough most days of the month, 3 months of a year for 2 successive years without other underlying disease to explain the cough. Breathlessness on exertion is eventually noticed, due to obstruction to airflow caused by swelling of the bronchial wall and the presence of mucus that cannot be cleared.

What Is Emphysema?

Emphysema is a condition in which there is overinflation of structures in the lungs known as alveoli (air sacs). As alveoli are destroyed, the lungs are unable to transfer oxygen to the bloodstream, which causes shortness of breath. This overinflation results from a breakdown of the walls of the alveoli, which causes a decrease in respiratory function. Damage to the walls, which are thin and fragile, is irreversible and results in permanent "holes" in the tissues of the lower lungs. The lungs also lose their elasticity, which is important to keep airways open. As a result, there is great difficulty breathing.

"Scientific research has shown that the normal lung maintains a remarkable balance between two types of chemicals with opposing action. One type of chemical is an enzyme that breaks down the elastic fibers in the lungs that allow it to expand and contract. The other type of chemical is an inhibitor of that same enzyme. Their opposing action creates the optimal degree of flexibility in the lungs while maintaining sufficiently strong structure to prevent collapse. When the chemical balance is altered, the lungs lose the ability to protect themselves against the destruction of these elastic fibers, as happens with emphysema."

There are a number of reasons this chemical imbalance occurs. Smoking is responsible for the majority (80% - 90%) of COPD cases, including emphysema.