Arterial Blood Gases

Overview & Description

Arterial blood gases, called ABGs, are a series of bloodmeasurements that are ordered as a single test. This test isused mainly to check lung function and acid levels in the body.

Who is a candidate for the test?

Any time there is a question about breathing problems,oxygen and carbon dioxide exchange, or acid levels in the body, this testcan be helpful. Examples include:

  • people with shortness of breathdue to lung problems
  • people with rapid breathing due to heart or blood conditions
  • people who are unconscious
  • people who are suspected of having too much or too little acid in thebody, such as someone with kidney failure
  • people on artificial breathing machines calledventilators.ABGs are done regularly to assure that the machines are set correctly.
  • How is the test performed?

    A blood sample from an artery is needed to do this test.In most cases, an artery on the palm side of the wrist is used to get theblood. Sometimes, an artery in the groin or other area may be used.The skin over the artery is cleaned first. Next, a small needle is insertedthrough the skin and into the artery. The needle is usually hooked up toa syringe. Blood flows into the syringe once the needle is put into theartery. Pressure is applied over the area after the blood is collected toprevent bleeding. The blood is then sent to the lab for analysis.

    Preparation & Expectations

    What is involved in preparation for the test?

    Most of the time, there is no preparation needed for this test.A doctor will give any instructions if needed.

    Results and Values

    What do the test results mean?

    There are several values that are measured in an ABG.Each of the values has a set range that is considered to be withinhealthy limits. If anyof the main values becomes severely abnormal, the person may die.

    pH Level

    The pH is one of the main parts of this test. This is ameasure of the level of acid in the blood. Acid levels may be too high with:

  • kidney failure or damage
  • certain cases of uncontrolled diabetes
  • exposure to certain toxic substances, such as a drug overdose
  • shock, which may occur from heart failure, serious infections, ormassive blood or fluid loss
  • breathing troubles, such as lung infections,asthma, emphysema,or not breathing fast enough
  • certain medicines
  • Acid levels may be too low from:

  • dehydration
  • certain types of kidney problems
  • breathing too fast, such as when a person has apanic disorder
  • excessive vomiting
  • salt imbalances,which may result from a hormone problem in the body
  • certain medicines
  • If the pH is abnormal, the other parts of the test can helpfind out the reason. For example, if the acid level in the body is toohigh, it could be from breathing or metabolism problems. It is crucialto know what is causing the high acid level so that the best treatment canbe chosen. If the acid level is too high because of a breathingproblem, the person may need extra oxygen or even a ventilator.If the acid level is too high from metabolism problems, a personmay need to be hooked up to a blood-filtering machine or may needantibiotics or other medicines.

    Oxygen and Carbon Dioxide Levels

    Other parts of the test are the oxygen andcarbon dioxide levels in the blood. The job of the lungs is to takein oxygen and get rid of carbon dioxide. If some type of breathingor respiratory problem is present, these values will be abnormal.The oxygen level can also be used to check if a person is gettingenough oxygen or whether they need extra oxygen.

    Bicarbonate Level

    The part of the test that measures the bicarbonate levelin the blood will determine whether there is a metabolism problem.

    Other minor parts of the test may bemonitored by a doctor in certain situations.

    The doctor must look at the pH, breathing, and metabolicparts of the test as a whole. This allows the doctor to sort out differentproblems in a person’s body.

    Article type: xmedgeneral