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.