therefore even differences in conductivities between regions will not cause lateral heat exchange each region will have its own conductivity k and geometry u00d7 g each one of these elements making a 34 small 34 contribution to the changes in temperature of the blood and the water total heat exchange being the sum of all of the elements equ8 which is the previously described measurement in addition to the steady state measurement equilibrated several opportunities for making transient measurements exist for example an impulse step or ramp function can be introduced to the heat exchanger flow rate causing a response in u03b4t w and q b similarly a transient can be introduced into the heat exchanger inlet temperature t w which in turn causes a different response in the heat diffusion equation and q w additionally by use of a conventional pressure cuff as used on commercial sphignomanometers partial or total occlusions can be effected under program control to generate transient as well as steady state responses in the blood flow these operations can be employed to further evaluate k and to use the results as a classification factors in the data base conventional analysis techniques exist which allow for the quantitative determination of the transient system characteristics allowing an impulse response to be estimated which further characterizes the measurement an additional characteristic of the invention is to determine the real time ejection volume of the left ventricle lvev in that is is frequently symptomatic of pathologies associated with the cardiovascular system the mean cardiac.