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Arterial blood gas
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An arterial blood gas is a lab test run on blood drawn from an artery, not from a vein like most blood work. That blood is used to measure the partial pressures of two gases, oxygen and carbon dioxide, which is how the amount of each gas dissolved in the blood is expressed. It is a snapshot of gas exchange taken inside the artery.
Each number tells you something different. The partial pressure of oxygen speaks to oxygenation, that is, how much oxygen is reaching the blood. The partial pressure of carbon dioxide speaks to ventilation, meaning how much air is moving in and out of the lungs. Most analyzers also measure pH, which shows how acidic the blood is.
Carbon dioxide is the value that moves with breathing. It rises or falls if a person hyperventilates, which means breathing fast or deeply, or hypoventilates, which means breathing slowly or shallowly, and it also changes with the body's acid base status.
In brief
An arterial blood gas tests blood drawn from an artery and measures the partial pressures of oxygen and carbon dioxide.
It is a snapshot of gas exchange taken inside the artery.
The partial pressure of oxygen reflects oxygenation and the partial pressure of carbon dioxide reflects ventilation; most analyzers also measure pH.
The partial pressure of carbon dioxide shifts with hyperventilation, with hypoventilation and with acid base status.
Sources (1)
- National Center for Biotechnology Information, StatPearls PublishingArterial Blood Gas Analysis: Fundamentals, Interpretation, and Clinical Utility, StatPearlsPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
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