What is the normal reference range for arterial oxygen tension (pO2) in mmHg?

• A. 80-100 mmHg
• B. 50-70 mmHg
• C. 110-120 mmHg
• D. 30-50 mmHg

Answer: (A)

Arterial oxygen tension, or pO2, is the amount of oxygen dissolved in arterial blood and shows how effectively oxygen moves from the lungs into the blood. It’s measured in arterial blood gases and reflects oxygen transfer, while the total oxygen content also depends on how much hemoglobin is carrying O2.

In healthy individuals breathing room air at sea level, PaO2 is normally in the range of about 80 to 100 mmHg. Values below this range signal hypoxemia, indicating reduced oxygen transfer to the blood. Values above this range aren’t typical at rest on room air and usually point to supplemental oxygen or other reading conditions. Therefore, the normal reference range is 80–100 mmHg.