Analysis and characterization of photo-plethysmographic signal

Qualitative assessment of the overall clinical status of the subject and ch aracterization of complex cardiovascular dynamics from digital blood volume pulsations measured noninvasively using a photo-plethysmographic device is addressed. A novel concept is employed to detect the dominant nonsinusoida l periodicity embedded in the data series and to extract the associated per iodic component. The detection and the extraction of periodic component is performed with moving window to accommodate the variations of the physiolog ical oscillations. The covariance matrix formed by the gradually varying pa ttern is used as a simple measure of qualitative assessment. Further, the c haracterization of the underlying system in the light of nonlinear: dynamic al analysis is also presented. The stable subjects are shown to behave as a low-dimensional system whereas the diseased subjects exhibit comparatively high dimensional activity.