What is considered a normal value for mixed venous oxygen saturation (SvO2)?

• A. 60-65%
• B. 80-85%
• C. 70-75%
• D. 50-60%

Answer: (C)

SvO2 shows the balance between oxygen delivery and oxygen consumption by tissues. In healthy physiology, mixed venous oxygen saturation sits in roughly the mid 60s to mid 70s percent, with many references citing about 70–75% as a typical normal value. So the range around 70–75% best represents normal SvO2, indicating tissues are extracting a normal amount of oxygen. If SvO2 drops toward the 60s or lower, delivery is not meeting demand (low cardiac output, anemia, hypoxemia). If SvO2 rises into the 80s or higher, it can mean reduced tissue extraction or very high delivery relative to consumption (as in certain shock states or mitochondrial dysfunction). Among the options, 70–75% aligns most closely with the standard normal range.