How Is ARDS Diagnosed?

Your doctor will diagnose ARDS based on your medical history, a physical exam, and results from tests.

Medical History

Your doctor will ask about conditions you may have or have recently had that can lead to ARDS. For a list of these conditions, see "Who Is At Risk for ARDS?" Your doctor also will ask whether you have heart problems, such as heart failure, which can cause fluid to build up in your lungs.

Physical Exam

ARDS may cause abnormal breathing sounds, such as crackling. Your doctor will listen to your lungs with a stethoscope to hear these sounds.

He or she also will listen to your heart and look for signs of extra fluid in other parts of your body. Extra fluid may mean you have heart or kidney problems.

Your doctor will look for a bluish color on your skin and lips. A bluish color means your blood has a low level of oxygen. This is a possible sign of ARDS.

Diagnostic Tests

Diagnostic tests are used to find the cause of your symptoms. You may have ARDS, or you may have another condition that causes similar symptoms.

Initial Tests

The first tests done are:

• An arterial blood gas test. This blood test shows the oxygen level in your blood. A low level of oxygen in the blood may be a sign of ARDS.
• Chest x ray. This test is used to take a picture of your lungs. It can show whether you have extra fluid in your lungs.
• Blood tests, such as a complete blood count, blood chemistries, and blood cultures. These tests help find the cause of ARDS, such as an infection.
• Sputum cultures. This test looks at the spit you've coughed up from your lungs. It can help find the cause of an infection.

Other Tests

Other tests used to diagnose ARDS include:

• Computed tomography (to-MOG-rah-fee), or CT, scan. This test uses a computer to take detailed pictures of your lungs. It may show lung problems, such as fluid in the lungs, signs of pneumonia, or a lung tumor.
• Heart tests that look for signs of heart failure. Heart failure is a condition in which the heart can't pump blood the way it should. This condition can cause fluid to build up in your lungs.