Arterial Blood Gas Test

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KEY POINTS

• An arterial blood gas test measures how well the body uses oxygen and gets rid of carbon dioxide. It also measures the balance of acids and bases in your child’s blood (called the pH).
• A small amount of blood is taken from an artery in your child’s arm with a needle. An artery is a vessel that carries oxygen-rich blood from the heart and lungs to the rest of the body. The artery most commonly used for this test is the artery in the wrist where your child’s pulse is usually checked. For newborns, blood may be taken from the umbilical cord.
• Talk to your child’s healthcare provider about what the test results mean and ask any questions you have.

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What is the arterial blood gas test?

An arterial blood gas (ABG) test is a blood test that measures the levels of oxygen and carbon dioxide in your child’s blood. It also measures the balance of acids and bases in the blood (called the pH).

Why is this test done?

This test measures how well the body uses oxygen and gets rid of carbon dioxide. Blood gas tests may be done when your child has an injury or illness that affects breathing, or if your child is having trouble breathing. It may be done to:

• Check how well your child’s lungs are working.
• Check how well oxygen therapy or other breathing treatments are working.
• Get information about whether your child’s blood has the right balance of acids and bases.

How do I prepare my child for these tests?

There is usually no special preparation for these tests. If your child is using oxygen therapy, be sure to tell the technician how much oxygen your child is on, for example, 2 liters per minute, and how many minutes or hours your child has been on oxygen before the test.

How is the test done?

A small amount of blood is taken from an artery in your child’s arm with a needle. An artery is a vessel that carries oxygen-rich blood from the heart and lungs to the rest of the body. The artery most commonly used for this test is the artery in the wrist where your child’s pulse is usually checked. Medicine to numb to spot where the needle goes in may be used. For newborns, blood may be taken from the umbilical cord.

If your child is hospitalized and needs frequent testing, your child may have a small tube (catheter) put in his artery. The tube can stay there for several days. The blood needed for an arterial blood gas test can be taken from this tube without sticking your child’s artery with a needle each time.

The blood is tested in a lab right away to get the most accurate results.

Having this test will take just a few minutes.

Ask your healthcare provider when and how you will get the result of the test.

What does the test result mean?

Many health problems can cause abnormal ABG results. Examples of possible causes of an abnormal result are:

• Your child’s body is not getting enough oxygen from the lungs because of lung disease or illness, or because of other problems such as a very low blood count.
• Your child’s body is not getting rid of enough carbon dioxide because of lung disease or other breathing problems.
• Your child’s kidneys are not working properly.
• Your child has had loss of normal body fluids, such as from severe vomiting or diarrhea.
• Your child has extra fluid in his body, such as from heart problems.
• Your child has diabetes and his blood sugar is very high.

What if my child’s test result is not normal?

Test results are only one part of a larger picture that takes into account your child’s medical history and current health. Sometimes a test needs to be repeated to check the first result. Talk to your child’s healthcare provider about what your child’s results mean.

If your child’s test results are not normal, ask your child’s healthcare provider:

• If your child needs more tests
• What kind of treatment your child might need
• What lifestyle, diet, or other changes your child might need to make