How Is COPD Diagnosed?

Your doctor will diagnose COPD based on your signs and symptoms, your medical and family histories, and test results.

He or she may ask whether you smoke or have had contact with lung irritants, such as air pollution, chemical fumes, or dust. If you have an ongoing cough, your doctor may ask how long you've had it, how much you cough, and how much mucus comes up when you cough. He or she also may ask whether you have a family history of COPD.

Your doctor will examine you and use a stethoscope to listen for wheezing or other abnormal chest sounds.

You also may need one or more tests to diagnose COPD.

Lung Function Tests

Lung function tests measure how much air you can breathe in and out, how fast you can breathe air out, and how well your lungs can deliver oxygen to your blood.

The main test for COPD is spirometry (spi-ROM-eh-tre). Other lung function tests, such as a lung diffusing capacity test, also may be used. (For more information, see "Types of Lung Function Tests.")

Spirometry

During this painless test, a technician will ask you to take a deep breath in and then blow as hard as you can into a tube connected to a small machine. The machine is called a spirometer.

The machine measures how much air you breathe out. It also measures how fast you can blow air out.

Spirometry

The photo shows how spirometry is done. The patient takes a deep breath and then blows hard into a tube connected to a spirometer. The spirometer measures the amount of air exhaled and how fast it was blown out.

Your doctor may have you inhale medicine that helps open your airways and then blow into the tube again. He or she can then compare your test results before and after taking the medicine.

Spirometry can detect COPD long before its symptoms appear. Doctors also may use the results from this test to find out how severe your COPD is and to help set your treatment goals.

The test results also may help find out whether another condition, such as asthma or heart failure, is causing your symptoms.

Other Tests

Your doctor may recommend other tests. These tests include:

• A chest x ray or chest computed tomography (CT) scan. These tests create pictures of the structures inside your chest, such as your heart and lungs. The pictures can show signs of COPD. They also may show whether another condition, such as heart failure, is causing your symptoms.
• An arterial blood gas test. This blood test measures the oxygen level in your blood using a sample of blood taken from an artery. The test can help find out how severe your COPD is and whether you may need supplemental oxygen therapy.