A PaO2 test measures partial pressure of oxygen, or PaO2the oxygen pressure in arterial blood.
The PaO2 reflects how well oxygen is able to move from the lungs to the blood.
It is often altered by severe illnesses, with the PaO2 test results used to guide treatment.
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What Is Partial Pressure of Oxygen?
Oxygenation of tissues happens when oxygen moves from red blood cells into your tissue cells.
Purpose of PaO2 Test
The PaO2 test measures the pressure of oxygen in your blood.
The measurement is taken during anarterial blood gas (ABG) test.
The results are often used to determine whether emergency treatmentsuch asoxygen supplementationormechanical breathing supportare needed.
Breathing problems can disrupt the natural exchange between oxygen and carbon dioxide.
A PaO2 test can shed light on why.
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This video has been medically reviewed bySanja Jelic, MD.
Risks and Contraindications
A PaO2 test has very few risks associated with it.
Before the PaO2 Test
A PaO2 test as part of an outpatient diagnostic evaluation requires an appointment.
However, the test can be done urgently during a respiratory emergency.
What to Wear
Dress comfortably for a PaO2 test.
Often, blood is drawn from theradial artery, which runs along the inner surface of the wrist.
If you have time, you may wish to shop around and compare prices.
They can vary considerably.
Pre-Test
First, you’ll have your arterial pulse checked.
While blood is usually drawn from the radial artery in your wrist, this is not always ideal.
In this case, your PaO2 can be checked without a needle puncture.
Typically, blood pumps rapidly through the arteries.
This is why the volume of blood needed for your test can be collected quickly.
You might also need to have gauze wrapped around your wrist for a few hours.
Your wrist may feel a bit sore for several days after the test.
Many people are able to resume normal activities soon after having a PaO2 test.
Ask your healthcare provider to be sure.
Ask your healthcare provider if you might use mild pain relievers for soreness and pain.
Interpreting Results
Each breath delivers air to thealveoliin your lungs.
There, oxygen and carbon dioxide are transferred between the lungs and the blood.
If your PaO2 is below the normal range, that is not the case.
Lung diseases and breathing problems can increase the risk of developing low PaO2.
Talk to your healthcare provider for their interpretation of the results.
You may need to have a follow up PaO2 test, especially if your symptoms don’t improve.
You may also need a follow-up test when it’s time to change your oxygen supply or ventilation assistance.
Summary
The PaO2 test is used to evaluate respiratory diseases and conditions that affect the lungs.
The results are often used to determine whether emergency treatmentsuch asoxygen supplementationormechanical breathing supportis needed.
Like other lab tests, the PaO2 test is over in no time.
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