1. SVO2

2. SVO2 : What is it? Oxygen saturation in the pulmonary artery.
This represents the “mixed venous” or the measure of the average venous oxygen saturation throughout the body.
The pulmonary artery is the last stop before Hb is resaturated in the capillary beds of the lungs.
SVO2 is oxygen that was not utilized.

3. SVO2 : What is it? …continued
By Fick Equation the difference between SaO2 and SVO2 is the oxygen utilization or roughly oxygen consumption.
A normal difference between SaO2 and SvO2 is 25%
Usually no less than 20%....even in a coma.
Usually no more than 45%...even under extreme stress or exercise.

4. SVO2: Equipment
Monitor

5. SVO2: Equipment
Catheter

6. SVO2: Monitoring Significance of SVO2
The things that cause a drop in SVO2
Hypoxemia
Increase in oxygen consumption
Decrease in cardiac output

7. }
22% used
Blood move thru body capillaries
PaO2 100 = 97%
75% SvO2

8. }
22% used
SvO2 – 60%
Hypoxemia
SaO2 – 82%

9. Oxygen Consumption Patient activity Sedatives wear off Shivering
Fighting the vent
Getting out of bed
Any of these will potentially increase O2 consumption and decrease SvO2

10. Q (cardiac output)
With blood moving slower, more oxygen is extracted from any given unit of blood. It therefore comes back more desaturated.
If cardiac output drops in half, twice as much oxygen must be extracted from the same unit of blood!

11. RRT Question Alert:
In the presence of normal oxygenation, and no increase in patient activity…a drop in SVO2 means a drop in Cardiac output!