Arterial Blood Gases
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
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
local anesthetic to numb that area.
the needle into the artery. More than one needle stick may be
- 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
- 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).
How It Feels
Collecting blood from an artery is more
painful than collecting it from a vein because the arteries are deeper and are
protected by nerves.
- Most people feel a brief, sharp pain as the
needle to collect the blood sample enters the artery. If you are given 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
- You may feel more pain if the person drawing your blood has a
hard time finding your artery, your artery is narrowed, or if you are very
sensitive to pain.
There is little chance of a problem from having
a blood sample taken from an artery.
- You may get a small bruise at the site. You can
lower the chance of bruising by keeping pressure on the site for at least 10
minutes after the needle is removed (longer if you have bleeding problems or
take blood thinners).
- You may feel lightheaded, faint, dizzy, or
nauseated while the blood is being drawn from your artery.
bleeding can be a problem for people with bleeding disorders. Aspirin, warfarin
(Coumadin), and other blood-thinning medicines can make bleeding more likely.
If you have bleeding or clotting problems, or if you take blood-thinning
medicine, tell your doctor before your blood sample is taken.
rare occasions, the needle may damage a nerve or the artery, causing the artery
to become blocked.
Though problems are rare, be careful with the arm or leg
that had the blood draw. Do not lift or carry objects for about 24 hours after
you have had blood drawn from an artery.