Patent ID: 7590437

Claim:
A method of measuring in absolute physical units cardiac output of a subject comprising: a) administering to a cardiovascular system of the subject a detectable amount of at least one indicator; b) applying a first wavelength of light for exciting the indicator within the cardiovascular system and causing the indicator to emit a second wavelength of light, wherein the second wavelength of light is fluorescence emitted by the indicator; c) measuring intensity of fluorescence emitted by the indicator in the cardiovascular system over a period of time using at least one photodetector proximately located to at a detection area of the subject; d) converting the measured intensity of the fluorescence over the period of time to a measured concentration of the indicator over a period of time using a known calibration curve that defines how the concentration of the indicator in the cardiovascular system varies as a function of the measured value of the intensity of the fluorescence; e) determining cardiac output of the subject in absolute units of volume over time based on the measured concentration of the indicator over the period of time.