Fick principle (calculation of cardiac output)
The essence of the Fick principle is that blood flow to an organ can be calculated using a marker substance if the following information is known:
Amount of marker substance taken up by the organ per unit time
Concentration of marker substance in arterial blood supplying the organ
Concentration of marker substance in venous blood leaving the organ.
In Fick’s original method is measured the volume of oxygen, the oxygen concentration of blood from the pulmonary vein and the oxygen concentration of blood from an intravenous cannula .
|Cardiac output ( the volume of blood being pumped by the heart) (ml/min)
|The oxygen consumption (ml/min)
|Oxygen concentration of arterial blood ( millilitres of oxygen per 100 millilitres of blood ) (dimensionless)
|Oxygen concentration of mixed venous blood ( millilitres of oxygen per 100 millilitres of blood) (dimensionless)