What is the normal arterial oxygen tension (PaO2) range?

What is the normal arterial oxygen tension (PaO2) range?

• A. 80-100
• B. 95-100
• C. 90-110
• D. 70-90

Answer: (B)

PaO2 reflects how well oxygen is transferring from the lungs into the blood. In a healthy adult breathing room air at sea level, the alveolar PO2 is about 100 mmHg, and the arterial PO2 tends to be just under that, typically in the mid to high 90s. Because of this close match, the range around 95–100 mmHg is what you’d usually expect for normal arterial oxygen tension. Some references list a broader normal span (about 80–100 mmHg), but physiologically the most characteristic value sits in the mid-to-high 90s, making 95–100 the best match among the options. Values lower than this suggest reduced oxygenation (hypoxemia), while higher values can occur with high inspired oxygen or in certain clinical situations.

PaO2 reflects how well oxygen is transferring from the lungs into the blood. In a healthy adult breathing room air at sea level, the alveolar PO2 is about 100 mmHg, and the arterial PO2 tends to be just under that, typically in the mid to high 90s. Because of this close match, the range around 95–100 mmHg is what you’d usually expect for normal arterial oxygen tension. Some references list a broader normal span (about 80–100 mmHg), but physiologically the most characteristic value sits in the mid-to-high 90s, making 95–100 the best match among the options. Values lower than this suggest reduced oxygenation (hypoxemia), while higher values can occur with high inspired oxygen or in certain clinical situations.