EP3915467A1 — Quantification of absolute blood flow in tissue using fluorescence-mediated photoplethysmography

USPTO Abstract

A method, an apparatus, and a kit including the apparatus and a fluorescence agent are provided for measuring a time-varying change in an amount of blood in a tissue volume, and include exciting a fluorescence agent in the blood, acquiring a time-varying light intensity signal during a pulsatile flow of the blood through the tissue volume, the pulsatile flow having a systolic and a diastolic phase resembling a conventional photoplethysmogram, and processing the acquired signal to obtain a measurement of the time-varying change in the amount of blood in the tissue volume. The instantaneous molar concentration of the fluorescence agent is determined by utilizing a concentration-mediated change in a fluorescence emission spectrum of the fluorescence agent. There is further provided a fluorescence agent for use in the method.