For more than 50 years, CPB has been used to mechanically support the functions of the heart and lungs. In early studies, systemic oxygen uptake, calculated using Ficks global principle, was used to assess the efficiency of CPB. Using this measure of efficiency, a pump flow rate in liters per minute, based on the product of the body surface area (BSA) and a constant of 2.4 was found adequate to perfuse the body during normothermia. Ficks global principle is still used together with other methods to secure adequated perfusion under CPB.~The purpose of this study is to determine whether the patients cardiac output measured before CPB, is more sufficient to secure the patients oxygen needs than the estimated cardiac output from Ficks principle, and thereby prevent organ failure.~The hypothesis is that the patients cardiac output is a better marker for the optimal cardiac output than the estimated cardiac output.
The purpose of this study is to determine whether the patients cardiac output measured before cardiopulmonary bypass (CPB), is more sufficient to secure the patients oxygen needs than the estimated cardiac output from Ficks principle, and thereby prevent organ failure.