Which arterial blood gas value would indicate good oxygenation?

• A. PaO2 60 mmHg
• B. PaCO2 40 mmHg
• C. pH 7.40
• D. PaO2 95 mmHg

Answer: (D)

PaO2 measures the amount of oxygen dissolved in arterial blood, which reflects how well oxygen is moving from the lungs into the bloodstream. A normal PaO2 is roughly 80–100 mmHg, so a value of 95 mmHg sits squarely within that range and indicates good oxygenation. A PaO2 of 60 mmHg would indicate hypoxemia, meaning oxygen transfer is inadequate. PaCO2 shows ventilation status and can be normal even when oxygenation is impaired, and pH reflects acid-base balance rather than oxygen content. Therefore, the PaO2 of 95 mmHg best indicates good oxygenation.