Parameter optimization method for less-invasive and beat-by-beat estimation of E/sub max/

A new method for less-invasive and beat-by-beat estimation of the maximum ventricular elastance (E/sub max/) has been proposed. The method (parameter optimization method) needs only two measurements: aortic pressure and flow. In the estimation process, least squares method was applied to an identity equation based on a simple electrical circuit model of the systemic circulation. In the model, the left ventricular elastance was approximated by a linear time function. In vivo experiments using an adult goat yielded small estimation errors of aortic flow less than about 1.5 L/min. Stability of estimation was also good.