Blood gases

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Blood gases test

Overview

Risks

Results

Blood gases

Definition:

Blood gases measure the pH (acidity), oxygen content, and carbon dioxide content of the blood. Usually, blood gases are used to analyze the arterial blood. In rarer cases, venous blood may be used.

Alternative Names:
Arterial blood gas analysis; ABG
How the test is performed:

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The test is performed by collecting a sample of blood from an artery. Using a small needle, the sample may be collected from the radial artery in the wrist, the femoral artery in the groin, or the brachial artery in the arm.

Before blood is drawn, the circulation to the hand may be tested (if the wrist is the site). After the blood is drawn, pressure is applied to the puncture site for at least 5 minutes to completely stop the bleeding.

The test must be sent to the laboratory for analysis immediately, or the accuracy of the results cannot be guaranteed.

How to prepare for the test:

There is no special preparation. If the person receiving the test is on oxygen, the oxygen concentration must remain constant for 20 minutes preceding the test. If the test is to be taken without oxygen, the oxygen must be turned off for 20 minutes before the sample is taken to ensure accurate test results.

Infants and children:

The preparation you can provide for this test depends on your child's age, previous experiences, and level of trust. For general information regarding how you can prepare your child, see the following topics:

Infant test or procedure preparation (birth to 1 year)
Toddler test or procedure preparation (1 to 3 years)
Preschooler test or procedure preparation (3 to 6 years)
Schoolage test or procedure preparation (6 to 12 years)
Adolescent test or procedure preparation (12 to 18 years)

How the test will feel:

A needle is inserted through the skin into the artery. The site may be anesthetized if you desire. There may be brief cramping or throbbing at the puncture site. The needle is withdrawn after the sample is collected.

Pressure is applied over the site for 5 - 10 minutes to prevent bleeding, and a bandage is applied over the puncture site. The site is observed for signs of bleeding or impairment of the circulation.

Why the test is performed:

The test is used to evaluate respiratory diseases and conditions that affect the lungs. It is used to determine the effectiveness of oxygen therapy. The acid-base component of the test also gives information on how well the kidneys are functioning.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org).