Patent ID: 7611470

Claim:
A method of measuring a parameter of the cardiovascular system of a subject in absolute physical units comprising: a) administering to the cardiovascular system a detectable amount of an indicator that fluoresces when illuminated; b) illuminating the indicator; c) measuring the intensity of the illumination that is reflected by or transmitted through a portion of the cardiovascular system; d) measuring the intensity of the fluorescence of the indicator that was administered while it is illuminated; e) taking a blood sample from the cardiovascular circulatory system; f) measuring the concentration of the indicator in the blood sample; g) waiting a period of time; h) administering a detectable amount of the indicator to the cardiovascular system for a second time; i) illuminating the indicator for a second time; j) measuring the intensity of the illumination for a second time that is reflected by or transmitted through a portion of the cardiovascular system; k) measuring the intensity of the fluorescence of the indicator that was administered for the second time while it is illuminated; i) determining the magnitude of the parameter in absolute physical units after the administration of the indicator for a second time based on the measured concentration of the indicator in the blood sample, the first and second measured intensity of the illumination, and the first and second measured intensity of the fluorescence.