Arterial Blood Gases

ABGs, Blood Gases

Results

An arterial blood gas (ABG) test measures the acidity (pH) and levels of oxygen and carbon dioxide in the blood.

Normal

Normal values may vary from lab to lab and depend upon the elevation above sea level. Results are usually available right away.

Arterial blood gases (at sea level and breathing room air)

Partial pressure of oxygen (PaO2):	75–100 mm Hg (9.9–13.2 kPa)
Partial pressure of carbon dioxide (PaCO2):	35–45 mm Hg (4.6–5.9 kPa)
pH:	7.35–7.45
Bicarbonate (HCO3):	20–29 mEq/L (20–29 mmol/L)
Oxygen content (O2CT):	15–22 mL per 100 mL of blood (6.6–9.7 mmol/L)
Oxygen saturation (O2Sat):	95%–100% (0.95–1.00)

The concentration of oxygen being breathed, called the fraction of inhaled oxygen (FiO2), is also usually reported. This is only useful if you are receiving oxygen therapy from a tank or are on a ventilator.

Many conditions can change blood gas levels. Your doctor will talk with you about any abnormal results that may be related to your symptoms and medical history.

Abnormal results may be caused by:

• Diabetes.
• Drug or alcohol overdose.
• Kidney failure.
• Lung diseases, such as chronic lung disease, a blood clot in the lungs, or pneumonia.
• Severe dehydration from severe burns, vomiting, diarrhea, or taking water pills (diuretics).
• Severe infection (sepsis).

Go to previous section	Go to top of page	Go to next section
Author:	Maria G. Essig, MS, ELS	Last Updated: June 17, 2008
Medical Review:	Anne C. Poinier, MD - Internal Medicine Robert L. Cowie, MB, FCP(SA), MD, MSc, MFOM - Pulmonology
© 1995-2009 Healthwise, Incorporated. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated.This information does not replace the advice of a doctor. Healthwise disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use. How this information was developed to help you make better health decisions.