What is the normal range for mixed venous oxygen saturation (SvO2) if arterial O2 saturation is 100%?

The normal range for mixed venous oxygen saturation (SvO2) in a healthy individual is typically around 70% to 75%. When arterial oxygen saturation is at 100%, it indicates that the blood is fully saturated with oxygen as it leaves the lungs. However, the SvO2 reflects the balance between oxygen delivery and utilization by the tissues.

In healthy individuals, this balance means that a proportion of the oxygen carried in the arteries is extracted by the body's tissues, leading to a lower SvO2 value. A mixed venous oxygen saturation within the range of 70% to 75% signifies that while the arterial blood is oxygen-rich, the body's tissues still consume a significant amount of that oxygen for metabolic processes.

Values outside this range, either lower or higher, could indicate underlying conditions. For instance, lower SvO2 might suggest increased oxygen demand, poor perfusion, or inadequate oxygen delivery, while a higher SV02 could indicate reduced metabolism in tissues or conditions like sepsis where the oxygen consumption is compromised.

Thus, the choice that indicates a normal range of 70-75% aligns with physiological expectations, making it the correct answer for this question.