Panic pO2 value is at or below which threshold?

• A. ≤ 40 mmHg
• B. ≥ 60 mmHg
• C. 50–70 mmHg
• D. 80–100 mmHg

Answer: (A)

Arterial pO2 tells us how much oxygen is dissolved in the blood and available to tissues. Normal is about 75–100 mmHg. As pO2 falls, oxygen delivery becomes more and more inadequate. When pO2 reaches 40 mmHg or lower, it signifies severe, life-threatening hypoxemia where tissues, including the brain and heart, are at real risk of not getting enough oxygen. This is why 40 mmHg or less is treated as a panic value—it triggers immediate urgent intervention, such as rapid oxygen therapy or advanced airway support.

The other ranges describe milder or normal oxygen levels and do not indicate the same immediate danger.