A blood gas test is also called an arterial blood gas test or a blood gas analysis. It measures oxygen and carbon dioxide levels in the blood. The test can also show blood pH levels and lung function.
Doctors often use blood gas tests in emergency situations to help diagnose the cause of breathing difficulty.
In this article, learn more about the purpose of a blood gas test and how to interpret the results.
A blood gas test can show how well the lungs, heart, and kidneys are working.
More specifically, results of the test can help a doctor to:
- diagnose lung and breathing problems
- check whether treatments for lung conditions are working
- determine whether a person has a ruptured blood vessel, metabolic disease, or chemical poisoning
Doctors also use the test to check the acid-base balances in people who:
- have kidney problems
- have diabetes
- are recovering from drug overdoses
A doctor usually performs the test in a hospital, and often in an emergency room, but some doctors can perform the blood gas test in clinics.
A doctor may start with a modified Allen testTrusted Source to determine how well blood is flowing to the hand. This involves applying pressure to the arteries in the wrist to obstruct the blow flow for no more than 15 seconds, causing the hand to change color.
The doctor will release the pressure, and if regular coloring returns to the hand within 5–15 seconds, the results are normal, and the blood gas test can begin.
If the color does not return in this period, it is not safe to continue with testing.
During the blood gas test, a doctor will use a small needle to draw blood from an artery in the wrist.
If a person is receiving oxygen therapy, they will need to stop using it for at least 20–30 minutes before the blood gas test, if possible.
Drawing blood from an artery can cause more pain than drawing blood from a vein because the arteries contain sensitive nerves and are located deeper within the body.
Any pain or discomfort last for a few minutes after the test. Some people may feel nauseous or dizzy while the doctor draws blood, especially if they are nervous.
To reduce bruising, a person can gently press on the area for a few minutes, once the doctor removes the needle.
Rarely, it is possible for the needle to cause damage or block the artery.
Anyone who has undergone a blood gas test should avoid heavy lifting for at least 1 day to prevent complications or injury.
