Arterial 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
Partial pressure of carbon dioxide (PaCO2):	35–45 mm Hg
pH:	7.35–7.45
Bicarbonate (HCO3):	20–29 mEq/L or 20–29 mmol/L
Oxygen content (O2CT):	15%–22% (15–22 mL per 100 mL of blood)
Oxygen saturation (O2Sat):	95%–100% (95–100 mL per 100 mL of blood)

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).

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Author:	Sydney Youngerman-Cole, RN, BSN, RNC	Last Updated July 28, 2006
Medical Review:	Caroline S. Rhoads, MD - Internal Medicine Robert L. Cowie, MB, FCP(SA), MD, MSc, MFOM - Pulmonology
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