Normal Venous Oxygen Composition Values
Normal mixed/central venous oxygen saturation (SvO2/ScvO2) is typically ~65% to 75%. [1], [2] Normal venous oxygen partial pressure (PvO2) is typically ~35 to 40 mmHg, and venous PO2 reference intervals commonly span ~30 to 50 mmHg in healthy adults. [1], [3]
Oxygen Saturation (SvO2/ScvO2)
- Normal SvO2 (mixed venous oxygen saturation) is typically 65% to 75%. [1], [2]
- A commonly cited “normal” target for SvO2 is ~75% under physiological conditions. [4]
- Some clinical references report venous oxygen saturation ranges approximately 60% to 85%. [5]
Oxygen Partial Pressure (PvO2)
- Normal PvO2 (venous PO2) is typically in the ~35 to 40 mmHg range. [1]
- Venous blood gas reference ranges in healthy adults commonly place venous PO2 around ~30 to 50 mmHg. [3], [5]
Oxygen Content (Interpretation Constraints)
Mixed venous oxygen saturation reflects oxygen extraction by tissues, which makes venous oxygen saturation sensitive to oxygen delivery (for example, low cardiac output) and oxygen consumption. [4]
Clinical Measurement Considerations
- Mixed venous oxygen saturation is obtained from central venous/mixed venous sampling near the pulmonary artery and is used to reflect whole-body oxygen balance. [1], [2]
- Venous blood gas samples can show lower PO2 than arterial blood due to tissue oxygen extraction. [6]
Reference Interval Variability
Venous blood gas reference intervals vary by laboratory method and by patient population, so local reference ranges should be used when available. [3], [6]
Practical Numeric Targets Used in Critical Care
- Common goal ranges for adequate oxygenation using central/mixed venous saturation metrics include ScvO2 >70% or SmvO2 >65%, with SmvO2 >75% described as favorable in some contexts. [2]