Blood Gas Test FAQ

A blood gas test measures the carbon dioxide and oxygen levels, as well as the pH balance of your blood.



What is a blood gas test used for?

A blood gas test, also called arterial blood gas (ABG), can help your doctor determine how well your lungs and kidneys function. Imbalances in your pH and blood gas levels can provide an early warning about conditions such as:

  • Lung disease.
  • Kidney disease.
  • Metabolic disease.
  • Head or neck injuries that affect breathing.

How is the test performed?

A technician will take a small sample of blood from an artery in your wrist, arm or groin.

Are there any side effects from an ABG test?

Because only a small sample of blood is required for the test, it’s considered low risk. If you’re dehydrated or have deep arteries, drawing blood may be more difficult. If you have a condition that may affect bleeding or if you’re taking blood thinners or other medications that may cause you to bleed more than expected, be sure to notify your doctor.

Side effects that could occur include:

  • Bleeding, bruising or infection at the puncture site.
  • Blood accumulation under the skin.
  • Feeling faint.

Call your doctor if side effects don’t go away or if you develop unexpected symptoms.

What are normal, healthy ranges of ABG results?

The ABG test will provide your doctor with a precise measurement of the carbon dioxide, oxygen and pH levels of your blood. Normal blood gas levels for someone living at sea level are:

  • Blood pH: 7.38 to 7.42
  • Partial pressure of oxygen (PaO2): 75 to 100 mm Hg
  • Partial pressure of carbon dioxide (PaCO2): 38 to 42 mm Hg
  • Oxygen saturation (SaO2): 94 to 100 percent
  • Bicarbonate (HCO3): 22 to 28 mEq/L

When will I get results?

Your doctor will contact you with the results.

Is there any paperwork I need to fill out before I come in for my test?

Be sure to download and fill out our pre-admission and medication forms. If you need pre-authorization, registration staff will help you obtain it.

Where do I go for the test?

Tests are performed in the blood gas lab on each campus:

  • Mountain View campus – The pulmonary function testing lab, located in the old main hospital.
  • Los Gatos campus – The respiratory therapy department, located in the main hospital.