Arterial Blood Gases (ABG) Test: About This Test

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What is it?

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

Why is this test done?

An arterial blood gas test is done to:

  • Check for severe breathing and lung problems.
  • Check how well treatments for lung problems are working.
  • Check for changes in how well your lungs, heart, or kidneys are working.

How can you prepare for the test?

  • Be sure to tell your doctor about all the non-prescription and prescription medicines and herbs or other natural health products you take.
  • Tell your doctor if you have had bleeding problems, or if you take aspirin or some other blood thinner.
  • Do not smoke just before the test or breathe second-hand smoke, carbon monoxide, or certain paint or varnish removers in closed or poorly ventilated areas.

What happens during the test?

A health professional takes a sample of your blood.

What else should you know about the test?

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

What happens after the test?

  • You may be able to go home right away.
  • You may get a small bruise at the site. Put pressure on the site for at least 10 minutes after the needle is removed (or longer if you have bleeding problems or take blood thinners).
  • Do not lift or carry objects for about 24 hours after you have had blood drawn from an artery.

When should you call for help?

Watch closely for changes in your health, and be sure to contact your doctor or nurse call line if you have questions about the test.

Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor or nurse call line if you are having problems. It's also a good idea to keep a list of the medicines you take. Ask your doctor when you can expect to have your test results.

Where can you learn more?

Go to https://www.healthwise.net/patientEd

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