This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
Which scientific principle is the basis for thermodilution method used in measurement of cardiac output by pulmonary catheter 
Select and explain. 
A. Hagen-Poisseuile principle, B. Stewa-Hamilton equation, C. Bernouli's principle, D. Universal Gas Equation
B: Stewa-Hamilton equation
Answer: B: Stewa-Hamilton equation 
Explanation: Ans. b. Stewa-Hamilton equation Stewa Hamilton equation The thermodilution technique has become the de-facto clinical standard for measuring cardiac output because of its ease of implementation and the long clinical experience using it in various settings. It is a variant of the indicator dilution methoddeg, in which a known amount of a substance is injected into peripheral vein and its concentration change measured over time in serial aerial samples. As its name implies, the thermodilution method uses a thermal indicator, whereas other indicator dilution methods use various substances, such as indocyanine green dye. The fundamental physical basis for the indicator dilution method is given by the Stewa-Hamilton equationdeg, named after the two investigators who were instrumental in the development of this technique