We’ve all run across the Fick equation for cardiac output at one time or another. There are very limited circumstances when we’d ever get to use it but at the same time it’s one of those simple but incredibly profound equations that’s also a foundation of pulmonary physiology.
The Fick equation is:
VO2 = oxygen uptake
CvO2 = mixed venous oxygen content
CaO2 = arterial oxygen content
And what it describes is:
It’s a mass-balance equation that basically says that what goes in must come out, but how do you get from oxygen uptake to cardiac output?