Why are arterial blood gases taken

This simple test involves giving a small sample of blood. Read on to find out what…. Health Conditions Discover Plan Connect. Blood Gas Test. Medically reviewed by Elaine K. Luo, M. Purpose Risks Procedure Results What is a blood gas test? Why is a blood gas test done?

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Medically reviewed by Natalie Butler, R. Medically reviewed by Deborah Weatherspoon, Ph. You may need this test if you have trouble getting oxygen into your systembecause you have a lung disease such as pneumonia or emphysema. But low oxygen levels and impaired gas exchange may be a sign of another disease or condition that has nothing to do with your lungs.

Your healthcare provider needs to know what's causing your breathing problems to prescribe the right treatment. If you are using supplemental oxygen to help you breathe, this test shows if you are getting enough extra oxygen. People on a breathing machine or who have kidney disease, kidney failure, diabetes, shock, chronic vomiting, or other conditions may have problems with the acid-base balance in their blood. Here are some of the more common reasons an ABG is ordered:.

You're being treated for a lung condition that affects how your body absorbs oxygen or gets rid of carbon dioxide. You're a smoker, and the healthcare provider needs to find out whether you have a disease such as congestive heart failure. Electrolytes , including the levels of sodium, potassium, and bicarbonate in your blood. Other blood tests , including blood count; magnesium; calcium; amylase; blood urea nitrogen, or BUN; creatinine and phosphorus; ketones; and lactate level tests.

These tests show how well your kidneys are working. Urine tests may also be done to find out how well your kidneys are working and to check overall health. If your healthcare provider suspects you have a lung disease or heart condition, you may need other tests to see how well your lungs work. These may include:. This test measures the amount of air you can breathe in and out, and how forcefully you can exhale.

Lung volume measurements. These tests find out how much you can inhale, how much you can exhale, and how much air is left in your lungs after you exhale. Lung diffusion capacity. This test measures the amount of oxygen that passes from your lungs to your bloodstream. Test results may vary depending on your age, gender, health history, the method used for the test, and other things.

Your test results may not mean you have a problem. Ask your healthcare provider what your test results mean for you. Partial pressure of oxygen, or PaO2.

This measurement shows the pressure of oxygen in your blood. Bicarbonate is a chemical buffer that keeps the pH of blood from becoming too acidic or too basic. O2 content measures the amount of oxygen in the blood. Oxygen saturation measures how much of the hemoglobin in the red blood cells is carrying oxygen O2. See how well treatment for lung diseases is working.

Find out if you need extra oxygen or help with breathing mechanical ventilation. Find out if you are receiving the right amount of oxygen when you are using oxygen in the hospital. Measure the acid-base level in the blood of people who have heart failure , kidney failure , uncontrolled diabetes , sleep disorders, severe infections, or after a drug overdose.

How To Prepare Tell your doctor if you: Take a blood thinner , or if you have had bleeding problems. Are taking any medicines. Are allergic to any medicines, such as those used to numb the skin anesthetics.

How It Is Done A sample of blood from an artery is usually taken from the inside of the wrist radial artery , but it can also be taken from an artery in the groin femoral artery or on the inside of the arm above the elbow crease brachial artery.

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 5 to 10 minutes possibly longer if you take blood-thinning medicine or have bleeding problems.

How It Feels Collecting blood from an artery is more painful than collecting it from a vein because the arteries are deeper and are protected by nerves. Most people feel a brief, sharp pain as the needle to collect the blood sample enters the artery.

If you are given a local anesthetic, you may feel nothing at all from the needle puncture, or you may feel a brief sting or pinch as the needle goes through the skin.

You may feel more pain if the person drawing your blood has a hard time finding your artery, your artery is narrowed, or if you are very sensitive to pain. Risks There is little chance of a problem from having a blood sample taken from an artery. You may get a small bruise at the site.

You can lower the chance of bruising by keeping pressure on the site for at least 10 minutes after the needle is removed longer if you have bleeding problems or take blood thinners. You may feel light-headed, faint, dizzy, or nauseated while the blood is being drawn from your artery. On rare occasions, the needle may damage a nerve or the artery, causing the artery to become blocked.

Results An arterial blood gas ABG test measures the acidity pH and levels of oxygen and carbon dioxide in the blood. Normal The normal values listed here—called a reference range—are just a guide. Results are usually available right away. Arterial blood gases at sea level and breathing room air footnote 1 Partial pressure of oxygen PaO2 : Greater than 80 mm Hg greater than What Affects the Test Reasons you may not be able to have the test or why the results may not be helpful include the following: You have a fever or an abnormally low body temperature hypothermia.

You have a disease that affects how much oxygen is carried in your blood, such as severe anemia or polycythemia. You smoke just before the test or breathe second-hand smoke, carbon monoxide, or certain paint or varnish removers in closed or poorly ventilated areas.

For example, they can't tell whether low levels are caused by lung or heart problems.