What is the normal oxygen saturation of the Right Atrium?

• A. 72-75%
• B. 95-99%
• C. 88-92%
• D. 98-100%

Answer: (A)

Normal oxygen saturation in the right atrium reflects venous blood returning from the body before it goes to the lungs. This blood has already delivered oxygen to tissues, so the saturation sits in the mid-range rather than arterial levels. In healthy individuals, central venous and right atrial O2 saturation is typically about 70-75%, with many values clustering around 72-75%.

Arterial blood, returning from the lungs to the left heart, has a saturation near 95-100%, so those ranges aren’t correct for the right atrium. A value around 88-92% would be higher than expected for venous blood at rest, and 98-100% is essentially arterial. Thus, 72-75% best matches the normal right atrial venous saturation.