Arterial blood gases (ABGs)

What’s covered?

Arterial blood gases (ABGs) are a type of diagnostic test that measure the amount of oxygen and carbon dioxide in a patient's blood. They provide information about how well the lungs, heart, and other organs are working to make sure the body is able to exchange oxygen and carbon dioxide properly. ABGs are important to diagnose diseases like COPD (Chronic Obstructive Pulmonary Disease), pneumonia, asthma, organ failure, or congestive heart failure.

An ABG sample is taken from an artery using a needle or a special device called an arterial puncture device. A person may need to have their arm bandaged after they get tested if they had an arterial puncture. The sample is sent off to the laboratory for analysis where it’s tested to determine levels of:

• Oxygen (O2)
• Carbon Dioxide (CO2)
• pH – which indicates acidity/alkalinity balance in the body
• Bicarbonate (HCO3-)
• Base excess (BE) – which measures how well your body's buffers are doing in controlling pH level changes
• Hemoglobin saturation with oxygen (SaO2).

Your doctor may also use ABGs to adjust medications such as oxygen therapy for patients who are having trouble breathing due to lung disease or heart failure. In addition, these tests can help determine how well someone is responding to treatments for conditions like asthma or COPD by tracking how their levels of oxygenation change over time. An ABG result that is abnormal could be indicative of many different medical issues, so further testing will often be necessary if results are abnormal. To find out more about blood testing, check our blood tests guide.