LAB TEST
Blood gases
Blood gases are a measurement of how much oxygen and carbon dioxide are in your blood. They also determine the acidity (pH) of your blood.
How the Test is Performed
Usually, blood is taken from an artery. In some cases, blood from a vein may be used (venous blood gas). Most commonly, blood may be collected from one of the following arteries: Radial artery in the wrist Femoral artery in the groin Brachial artery in the arm The health care provider may test circulation to the hand…
How to Prepare for the Test
There is no special preparation. If you are on oxygen therapy, the oxygen concentration must remain constant for 20 minutes before the test. Tell your provider if you are taking any blood-thinning medicines (anticoagulants), including aspirin.
How the Test will Feel
When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing or slight bruising. This soon goes away. Pain and discomfort tend to be worse than drawing blood from a vein.
Why the Test is Performed
The test is used to evaluate respiratory diseases and conditions that affect the lungs. It helps determine the effectiveness of oxygen therapy or non-invasive ventilation (BiPAP). The test also provides information about the body's acid/base balance, which can reveal important clues about lung and kidney function and…
Normal Results
Values at sea level: Partial pressure of oxygen (PaO2): 75 to 100 millimeters of mercury (mm Hg), or 10.5 to 13.5 kilopascal (kPa) Partial pressure of carbon dioxide (PaCO2): 38 to 42 mm Hg (5.1 to 5.6 kPa) Arterial blood pH: 7.38 to 7.42 Oxygen saturation (SaO2): 94% to 100% Bicarbonate (HCO3): 22 to 28…
What Abnormal Results Mean
Abnormal results may be due to lung, kidney, metabolic diseases, or medicines. Head or neck injuries or other injuries that affect breathing can also lead to abnormal results.
Risks
There is little risk when the procedure is done correctly. Veins and arteries vary in size from one person to another and from one side of the body to the other. Taking blood from some people may be more difficult than from others. Other risks associated with having blood drawn are slight, but may include: Fainting or…
References
Chernecky CC, Berger BJ. Blood gases, arterial (ABG) - blood. In: Chernecky CC, Berger BJ, eds. Laboratory Tests and Diagnostic Procedures . 6th ed. St Louis, MO: Elsevier Saunders; 2013:208-213. Weinberger SE, Cockrill BA, Mandel J. Evaluation of the patient with pulmonary disease. In: Weinberger SE, Cockrill BA,…
This is a summary. Read the full article at www.ucsfbenioffchildrens.org (reviewed 31/07/2022).
This page is general information and is not medical advice. It does not replace a registered doctor, and it is not a prescription or a recommendation to use any medicine or test. Prices are listed prices and may change. Always follow the advice of your doctor or pharmacist.