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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 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).

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 skin.
  • 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.

Risks

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.
  • Ongoing 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.
  • On 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.

WebMD Medical Reference from Healthwise

Last Updated: May 30, 2012
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

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