The use of pulmonary artery catheters has diminished so that other technologies are emerging. Central venous oxygen saturation measurement, SCVo2, as a surrogate for mixed venous oxygen saturation measurement, SVo2, is simple and clinically accessible.
In order to maximize the clinical utility of SCVo2 (or SVo2) measurement it is useful to review what the measurement means in a physiologic context, how the measurement is made, important limitations, and how this measurement may be helpful in common clinical scenarios. Compared to cardiac output measurement, SVo2 is more directly related to tissue oxygenation. Furthermore, when tissue oxygenation is a clinical concern SVo2 is less prone to error compared to cardiac output; where small measurement errors may lead to larger errors in interpreting adequacy of oxygen delivery. SCVo2 should be measured from the tip of a central venous catheter placed close to, or within, the right atrium to reduce measurement error.
- Correct clinical interpretation of SVo2, or its properly measured SCVo2 surrogate, can be used to
- estimate cardiac output using the Fick equation,
- better understand whether a patient's oxygen delivery is adequate to meet their oxygen demands,
- help resuscitate patients using validated Early Goal Directed Therapy treatment protocols,
- understand and treat arterial hypoxemia,
- and rapidly estimate shunt fraction (venous admixture).
