Bicarbonate: How It Is Done

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How It Is Done

Blood drawn from an artery

A sample of blood from an artery is usually taken from the inside of the wrist (radial artery), but it can also be collected 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.

To prevent the possibility of damaging the artery of the wrist when the blood sample is taken, 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 at least 5 to 10 minutes (possibly longer if you take blood-thinning medicine or have bleeding problems).

Blood drawn from a vein

The health professional drawing blood will:

• Wrap an elastic band around your arm to stop the flow of blood.
• Clean the needle site with alcohol.
• Put the needle into the vein. More than one needle stick may be needed.
• Attach a tube to the needle to fill it with blood.
• Remove the band from your arm when enough blood is collected.
• Apply a gauze pad or cotton ball over the needle site as the needle is removed.
• Apply pressure to the site and then a bandage.

Last updated:	June 17, 2008
Author:	Maria G. Essig, MS, ELS
Reviewed By:	Anne C. Poinier, MD - Internal Medicine, Robert L. Cowie, MB, FCP(SA), MD, MSc, MFOM - Pulmonology
Editors:	Susan Van Houten, RN, BSN, MBA, Tracy Landauer