The a-vO2 difference is defined as the difference between which two oxygen contents?

• A. Arterial oxygen content and venous oxygen saturation
• B. Arterial oxygen content and tissue oxygen content
• C. Arterial and venous oxygen content
• D. Venous oxygen content and tissue oxygen content

Answer: (C)

The a-vO2 difference shows how much oxygen the tissues extract by comparing the oxygen content of arterial blood with that of venous blood after circulation. It is the arterial O2 content minus the venous O2 content (CaO2 − CvO2), expressed as mL O2 per 100 mL of blood. This uses content, not saturation, and reflects the actual amount of O2 delivered and then removed by tissues. So it’s the difference between arterial oxygen content and venous oxygen content.