None of the current methods used to diagnose COPD can detect the disease before irreversible lung damage has occurred. However, 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 and will perform a physical exam. The 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 undergo one or more of the following tests:
Many tests of lung function have been developed, and each provides slightly different information about how well your lungs are working. Pulmonary function tests are painless, noninvasive tests that are performed using a machine called a spirometer. By breathing into the spirometer under certain conditions, the 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, and the doctor can then determine to what extent your lung function is diminished. Sometimes, tests are repeated after you have been given a bronchodilator medication, to see if your results improve with this type of treatment. Pulmonary function tests include:
Carbon Monoxide Diffusing Capacity: This test provides an estimate of how efficiently the lungs can exchange gases with the blood. You take a breath of a known mixture of gases and see what percent is left over at exhalation. Oximetry: A sensor on your finger is used to acquire quick, basic information about the amount of oxygen in your blood. More detailed measurements are provided by the 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, usually in the wrist. Sputum Test: Collecting a sputum specimen (a sample of coughed-up mucus) for laboratory testing can reveal the presence of an infection that could be complicating COPD. Chest X-Ray: A chest X-ray provides a picture of the heart, lungs, bones, and soft tissues in the chest, as well as the blood vessels associated with them. Computed Tomography (CT) Scan: This test provides a detailed X-ray of the lungs and 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, which 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. The substance can be replaced artificially by giving a medicine intravenously.