Diagnosis of Chronic Obstructive Pulmonary Disease (COPD):

Chronic bronchitis is diagnosed by the history of a prolonged productive cough. People with chronic obstructive bronchitis have chronic bronchitis and evidence of airflow obstruction on pulmonary function tests.  COPD is diagnosed on the basis of findings observed during a physical examination and on pulmonary function test results. However, by the time the doctor notices these abnormalities, COPD, also known as emphysema, may already be moderately severe. The most important determinant of how the person feels and functions is the severity of the airflow obstruction.

In mild COPD, the physician may find nothing unusual during the physical examination. As the disease progresses, wheezes may be heard through the stethoscope, and prolonged expiration and decreased breath sounds become apparent. Chest movement diminishes during breathing, and use of the neck and shoulder muscles in breathing may occur. In mild COPD, the chest x-ray is usually normal. As COPD worsens, the chest x-ray shows over-inflation of the lungs. Thinning of blood vessels suggests the presence of emphysema.

Physicians can evaluate airflow obstruction with forced expiratory spirometry (see Symptoms and Diagnosis of Lung Disorders: Lung Volume and Flow Rate Measurements). Decrease in the forced expiratory volume in 1 second (FEV1) and the ratio of the FEV1 to the forced vital capacity (FVC) are required to demonstrate airflow obstruction and to make the diagnosis.

A blood test may show an abnormally high level of red blood cells (polycythemia). Pulse oximetry or a sample of blood taken from an artery often shows low levels of oxygen. High levels of carbon dioxide in the arteries occur late in the course of the disease.

In people who develop COPD at a young age, especially when there is a family history of COPD, the alpha1-antitrypsin blood level is measured to determine whether alpha1-antitrypsin deficiency is present. This genetic disorder is also suspected when COPD develops in people who have never smoked.