Assessing determinism of photo plethysmographic signal

A study was performed to analyze the signal obtained from a noninvasive pho to-plethysmographic device from four subjects in different clinical conditi ons. With the help of the theory of nonlinear dynamics, it is verified that the cardiovascular dynamics is dominated by an underlying chaotic attracto r. A new robust and computationally efficient method is presented for the d etection of the hidden deterministic structure of a time series. It is show n that the degree of chaos as well as the underlying determinism is directl y related to the subject's clinical stability.