COPD cannot be detected before irreversible lung damage has occurred. But, the earlier it is detected, the sooner steps can be taken to modify further damage. When you first see your doctor, he or she will ask about your symptoms and medical history. A physical exam will be done. Your history and physical exam provide the most important information that is used for the diagnosis of COPD.
If your doctor suspects you might have COPD, you may have one or more of the following tests:
Many tests of lung function have been developed. Each provides slightly different information about how well your lungs are working. Pulmonary function tests are painless and noninvasive. They are performed using a machine called a spirometer. By breathing into the spirometer, your doctor can measure your lung volume and your ability to move air in and out of your lungs in a certain period of time. Your results are compared with typical findings of a healthy person your age and height. Your doctor can then determine to what extent your lung function is diminished. Sometimes, tests are repeated after you have been given a bronchodilator medication. This is to see if your results improve with this type of treatment.
Pulmonary function measures include:
Forced Vital Capacity (FVC)
—This is the maximum volume of air that can be forcibly exhaled after inhaling as deeply as possible.
Residual Volume (RV)
—This is the amount of air that remains in the lungs when measuring vital capacity after a maximal exhalation. In persons with COPD, RV is usually increased dramatically from normal because air is trapped in the damaged lung and cannot be exhaled normally.
Total Lung Capacity (TLC)
—This is the total amount of air the lungs are capable of holding. It is the combination of FVC and RV.
Forced Expiratory Volume in 1 Second (FEV
—This measures the volume of air that can be forcibly exhaled in one second. It represents the rate of air movement out of the lungs. FEV
typically declines a very small amount per year in normal persons. But, the decline can be several times greater in people with COPD.
Carbon Monoxide Diffusing Capacity
This test measures how well your lungs transfer a small amount of carbon monoxide gas into your blood. You take a breath of air containing a very small amount of carbon monoxide from a container. The amount of carbon monoxide in your exhaled air or arterial blood is then measured.
A sensor on your finger is used. It can quickly get basic information about the amount of oxygen in your blood. More detailed measurements are provided by a blood test called an arterial blood gas.
Arterial Blood Gases
Arterial blood gases determine the amount of oxygen and carbon dioxide in your bloodstream. This test requires that a blood sample be removed from one of your arteries. It is usually removed from your wrist, but sometimes your groin. It is done more often in an emergency room or hospital setting for someone who appears more seriously ill.
provides a picture of the heart, lungs, and bones. It also shows soft tissues in the chest, as well as the blood vessels associated with them.
This test provides a detailed x-ray of the lungs. It can be useful in assessing the extent of lung damage associated with COPD.
Levels of Alpha-1-Antitrypsin
This blood test measures levels of alpha-1-antitrypsin. This is an important protein that helps protect the lungs from damage due to inflammation. Persons who develop COPD at an early age, or who develop the disease but never smoked, may have abnormally low levels of this protein due to a genetic defect.