What is it?

An arterial blood gases (ABG) test is a blood test. It measures the acid-base balance (pH) and the levels of oxygen and carbon dioxide in the blood. It uses blood drawn from an artery. This is where the levels of oxygen and carbon dioxide can be measured before they enter body tissues.

Why is this test done?

An arterial blood gases test is done to check for severe breathing and lung problems. The test also checks how well treatments for lung problems are working. And the test can look for changes in how well your lungs, heart, or kidneys are working.

How do you prepare for the test?

Your doctor will tell you if there is anything you need to do to prepare for the test.

How is the test done?

A health professional uses a needle to take a blood sample. It's usually taken from the inside of the wrist. But it can also be taken from an artery in the groin or on the inside of the arm above the elbow crease.

How does having an arterial blood gases (ABG) test feel?

Collecting blood from an artery is more painful than collecting it from a vein. That's because the arteries are deeper and are surrounded by nerves.

Most people feel a brief, sharp pain as the needle to collect the blood sample enters the artery. If you get a local anesthetic, you may feel nothing at all from the needle puncture. Or you may feel a brief sting or pinch as the needle goes through the skin.

What happens after the test?

• You may be told to avoid lifting or carrying heavy objects for 24 hours after you've had blood drawn from an artery.