What Is a Blood Gas Test?

An arterial blood gas test, or blood gas test for short, typically involves using a needle to draw blood from the radical artery in the wrist, the brachial artery of the arm or the femoral artery of the groin. In rare cases, doctors use blood from the vein for this test.

Function

Doctors use blood gas tests to measure the carbon dioxide and oxygen levels of the blood. The test also determines the acidity, or pH, of the blood.

Significance

Abnormal results of a blood gas test can indicate that the body is not getting sufficient amounts of oxygen, is not expelling sufficient amounts of carbon dioxide or that its kidney function is encountering difficulty.

Features

Doctors order blood gas tests if patients show signs of an oxygen/carbon dioxide or pH imbalance; have a respiratory, kidney or metabolic disease and are suffering from respiratory distress; have head or neck trauma; have just undergone prolonged anesthesia for procedures such as cardiac bypass or brain surgery.

Preparation

Generally, there are no special steps that patients must take in preparation for a blood gas test. The only exception applies to patients receiving oxygen therapy, whose oxygen concentration must not change during the 20 minutes before the test.

Misconceptions

When undergoing arterial blood sample collection for a blood gas test, patients typically experience more discomfort than they would during tests for which blood is drawn from the vein.

References

• MedlinePlus: Blood gases
• LabTestsOnline.org: Blood gases

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Photo Credit

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