What are normal blood gas readings?

An arterial blood gas, also known as a blood gas or ABG, is a set of laboratory tests performed on a sample of blood from one of your arteries.

Purpose

ABGs are ordered to evaluate the balance between oxygen (O2) and carbon dioxide (CO2) in your body. The results also give your doctor a picture of the relative amounts of acids and bases in your body.

Features

A complete ABG result measures the following in your blood: pH (acidity/alkalinity), PaO2 (partial pressure of dissolved oxygen), SaO2 (arterial oxygen saturation), HCO3 (bicarbonate level) and PaCO2 (amount of dissolved carbon dioxide).

Identification

Your pH should be between 7.35 and 7.45. A PaO2 should be between 75 and 100 mmHg (millimeters of mercury), a normal PaCO2 is 35 to 45 mmHg and the SaO2 should stay between 94 and 100 percent. A normal HCO3 ranges from 22 to 26 mmHg.

Significance

Abnormal results can indicate that you're not getting enough oxygen, are retaining too much carbon dioxide or are experiencing a problem with body organs, such as kidney failure or uncontrolled diabetes.

Warning

These respiratory and metabolic problems are difficult to diagnose, so it's very important that you review your ABG findings with your doctor to fully understand what they mean.

References

• Lab Tests Online: Blood Gases
• Orlando Health: Interpretation of the Arterial Blood Gas

Resources

• Medline Plus: Blood Gases