An arterial blood gas (ABG) test measures the oxygen and carbon dioxide levels in your blood as well your blood's pH balance. The sample is taken from an artery, not a vein, and healthcare providers typically order it in certain emergency situations.
An arterial blood gas (ABG) test is a blood test that requires a sample from an artery in your body to measure the levels of oxygen and carbon dioxide in your blood. The test also checks the balance of acids and bases, known as the pH balance, in your blood.
Your body normally tightly regulates the amount of oxygen and carbon dioxide in your blood, because low blood oxygen levels (hypoxemia) can lead to many serious conditions and damage to individual organ systems, especially your brain and heart.
Arterial blood gas tests can help healthcare providers interpret conditions that affect your respiratory system, circulatory system and metabolic processes (how your body transforms the food you eat into energy), especially in emergency situations.
There’s also a test known as a "blood gas analysis," which uses a sample of blood from anywhere in your circulatory system (artery, vein or capillary). An arterial blood gas (ABG) test only tests a blood sample from an artery in your body.
Other common names for an arterial blood gas test include:
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An arterial blood gas test usually includes the following measurements:
Healthcare providers frequently order arterial blood gas (ABG) tests for the following settings or areas of medicine:
Healthcare providers evaluate several conditions using an ABG, including:
Your provider may also perform an arterial blood gas test if you have any of the following lung conditions to make sure your treatment is working properly:
A healthcare provider called a respiratory therapist usually performs blood draws for arterial blood gas tests from an artery in your wrist, arm or groin. The respiratory therapist then processes the sample or sends it to a lab very quickly where medical laboratory scientists process the sample.
A respiratory therapist may perform a blood circulation test called an Allen test before taking a sample for an arterial blood gas test from your wrist. An Allen test involves holding your hand high with a clenched fist. The respiratory therapist will then apply pressure to the arteries in your wrist for several seconds. This simple test makes sure both of the arteries in your wrist are open and working properly.
If you’re on supplemental oxygen therapy, the respiratory therapist may turn off your oxygen for about 20 minutes before the blood draw. This is called a room air test. If you’re unable to breathe without supplemental oxygen, they won't do this test.
Most blood tests take a blood sample from one of your veins. For an arterial blood gas test, a respiratory therapist will take a sample of blood from one of your arteries. This is because there are higher oxygen levels in blood from an artery than blood from a vein.
A respiratory therapist usually takes the sample from an artery inside your wrist known as the radial artery. Sometimes they may take a sample from an artery in your arm (brachial artery) or groin (femoral artery).
If a newborn needs an arterial blood gas test, a provider may take the sample from the baby's heel or umbilical cord.
Unfortunately, getting a blood sample from an artery is usually more painful than getting a sample from a vein. This is because arteries are deeper in your body than veins and are surrounded by nerves. You may feel light-headed, dizzy or nauseated while a provider takes blood from your artery.
An arterial blood gas test blood draw includes the following steps:
You may experience some bruising and/or soreness at the site of the needle injection. Your provider may recommend that you avoid lifting heavy objects for 24 hours after the blood draw.
There’s little risk associated with getting an arterial blood gas test when the respiratory therapist performs the procedure correctly. Arteries vary in size from one person to another and from one side of your body to the other, so taking blood from some people may be more difficult than from others.
Risks associated with having an arterial blood gas blood draw are rare, but may include:
Arterial blood gas (ABG) tests typically provide very quick results. Respiratory therapists and laboratory scientists commonly use automated blood gas analyzers, which provide results within 10 to 15 minutes.
Blood test reports, including arterial blood gas test reports, usually provide the following information:
If your arterial blood gas test results are abnormal, it may mean you:
An arterial blood gas test can help diagnose certain conditions. If your results are abnormal, your healthcare provider may order additional tests, such as other blood tests and/or imaging tests, to confirm or rule out a diagnosis.
Normal value ranges can vary slightly from lab to lab. When you get your blood test results back, there will be information that indicates what that lab’s normal ranges are for each measurement. If you have any questions about your results, be sure to ask your healthcare provider.
In general, normal values at sea level include:
At altitudes of 3,000 feet (900 meters) and higher, the normal oxygen level is lower.
If you have a chronic lung condition, such as COPD or asthma, you’ll likely need to see your healthcare provider regularly and undergo arterial blood gas tests to make sure your treatment is working. If you develop concerning symptoms related to your lung condition, call your provider as soon as possible.
A note from Cleveland Clinic
Arterial blood gas tests are an effective diagnostic tool, especially in certain emergency situations. Healthcare providers also use this test to monitor certain health conditions. If you need to get an arterial blood gas test, know that it’s a slightly different process than a regular blood draw and it might hurt a little more. If you have any questions about the process or what to expect, don’t be afraid to ask your healthcare provider. They’re there to help you.
Last reviewed by a Cleveland Clinic medical professional on 02/18/2022.
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