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How Is COPD Diagnosed?

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

Your doctor may ask whether you smoke or have had contact with lung irritants, such as secondhand smoke, air pollution, chemical fumes, or dust.

If you have an ongoing cough, let your doctor know how long you've had it, how much you cough, and how much mucus comes up when you cough. Also, let your doctor know 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. He or she also may recommend 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 deliver oxygen to your blood.

The main test for COPD is spirometry (spi-ROM-eh-tre). Other lung function tests, such as a lung diffusion capacity test, also might be used. (For more information, go to the Health Topics Lung Function Tests article.)

Spirometry

During this painless test, a technician will ask you to take a deep breath in. Then, you'll 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

Figure A shows normal red blood cells flowing freely in a blood vessel. The inset image shows a cross-section of a normal red blood cell with normal hemoglobin. Figure B shows abnormal, sickled red blood cells blocking blood flow in a blood vessel. The inset image shows a cross-section of a sickle cell with abnormal (sickle) hemoglobin forming abnormal strands.

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 breathed out. It also measures how fast the air 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 before symptoms develop. Your doctor also might use the test results 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, such as:

  • A chest x ray or chest CT scan. These tests create pictures of the structures inside your chest, such as your heart, lungs, and blood vessels. 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 results from this test can show how severe your COPD is and whether you need oxygen therapy.
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July 31, 2013