ASSESSING THE STATE OF THE CIRCULATORY-SYSTEM VIA PARAMETERS VS VARIABLES

The state of the cardiovascular system is traditionally evaluated by m easurement of one or more variables, although, in principle, it could be assessed by determining one or more of its parameters, Using a simp le model it is argued that the latter approach is more reliable, and t hus more attractive, than the former. It is shown that placing the foc us on the estimation of system parameters tends to require deeper insi ght into the properties and operation of the system than routine integ ration of measured variables, If the requirement is added that data co llection shall be by noninvasive means only, analysis becomes more com plex, as illustrated with data collected in space.