ESTIMATION OF SYSTEMIC VASCULAR RESISTANCE AND CARDIAC OUTPUT USING ARTERIAL PULSE OXIMETRY WAVEFORMS

摘要

The invention relates to a method to estimate sytemic vascular resistance (SVR) and cardiac output (CO) from a pulse oximeter (photoplethysmography, PTG), comprising the steps of generating arterial blood pulse wave forms having first and second peaks, generating a Fast Fourier Transform and calculating the ratio of the height of the second peak (B) to the first peak (A) across the entire measurement using the equation FFTRI to estimate SVR, and the equation CO=(SR/FFTRI)×80 to estimate CO, where SR=S2/S1 and wherein SI and S2 are the areas under the whole PTG wave and the part in diastolic phase, respectively.; $$ \sum _{n=2}^N{\mathrm{FFT}}^2\left(f_n\right)/\sum _{n=1}^N{\mathrm{FFT}}^2\left(f_n\right).$$