Chronic obstructive pulmonary disease, or COPD, is typically diagnosed based on symptoms, family and medical history, and test results. Captain Miller, what can you tell us about diagnosing COPD?
Well, Dr. Green, in addition to asking questions about symptoms and taking a detailed history, providers generally start with a physical examination. During the exam, the provider listens to the lungs using a stethoscope to detect decreased breath sounds, wheezing, or other abnormal chest sounds.
A provider typically recommends one or more tests to diagnose COPD. Pulmonary function tests measure how much air a person can breathe in and out, how fast they can exhale, and how well the lungs deliver oxygen to the blood.
The main pulmonary function test used to diagnose COPD is called spirometry. During this painless test, the patient is asked to take a deep breath in. Then, they blow as hard as they can into a tube connected to a small machine, called a spirometer. The spirometer measures how much and how fast air is expelled. A provider may ask the patient to inhale a medicine that helps open the airways, called a bronchodilator, and repeat the spirometry test to compare results.
Spirometry is also used to stage the severity of COPD, called GOLD staging. After a bronchodilator is given, the amount of air that can be forcefully exhaled in one second, called the FEV1, is compared to a normal FEV1. For example, a person with moderate, or stage 2, COPD has an FEV1 between 50 and 80 percent of a normal FEV1.
Other tests that may be recommended include imaging studies and an arterial blood gas test. Chest x-rays can show signs of COPD or other conditions that may be causing symptoms. Computed tomography, or CT, scans aren't generally necessary for diagnosing COPD. However, because patients with COPD have a higher risk for lung cancer, a CT scan may be recommended for screening.
An arterial blood gas test measures the oxygen level in the blood using a sample of blood taken from an artery. This test is not often used for diagnosing COPD, but for patients with severe COPD, the results of this test can help determine the need for oxygen therapy.