Arterial Blood Gases
How To Prepare
Tell your doctor if you:
If you are on oxygen therapy, the oxygen may be turned off for 20 minutes before the blood test. This is called a "room air" test. If you can't breathe without the oxygen, the oxygen will not be turned off.
Talk to your doctor about any concerns you have regarding the need for the test, its risks, how it will be done, or what the results may mean. To help you understand the importance of this test, fill out the medical test information form(What is a PDF document?).
How It Is Done
A sample of blood from an artery is usually taken from the inside of the wrist (radial artery), but it can also be taken from an artery in the groin (femoral artery) or on the inside of the arm above the elbow crease (brachial artery). You will be seated with your arm extended and your wrist resting on a small pillow. The health professional drawing the blood may rotate your hand back and forth and feel for a pulse in your wrist.
A procedure called the Allen test may be done to ensure that blood flow to your hand is normal. An arterial blood gas (ABG) test will not be done on an arm used for dialysis or if there is an infection or inflammation in the area of the puncture site.
The health professional taking a sample of your blood will:
- Clean the needle site with alcohol. You may be given an injection of local anesthetic to numb that area.
- Put the needle into the artery. More than one needle stick may be needed.
- Allow the blood to fill the syringe. Be sure to breathe normally while your blood is being collected.
- Put a gauze pad or cotton ball over the needle site as the needle is removed.
- Put a bandage over the puncture site and apply firm pressure for 5 to 10 minutes (possibly longer if you take blood-thinning medicine or have bleeding problems).