Patent ID: 6266546
Filing Date: 2001-07-24
Classification: A61B,A61M,B07C,G01N

Abstract:
A system for determining a first biological constituent value of the blood of a patient, the blood having a second biological constituent different from said first biological constituent and flowing in a pulsatile fashion in a body part of the patient or in an extracorporeal passageway in communication with the circulatory system of the patient so as to be subjectable to transcutaneous examination in the body part or to noninvasive examination in the extracorporeal passageway, the body part or the extracorporeal passageway defining a blood conduit, the system comprising:blood conduit receiving means for receiving a blood conduit containing the flowing blood of the patient;a first emitter means positioned on said conduit receiving means for emitting a first radiation wavelength;a second emitter means positioned on said conduit receiving means for emitting a second radiation wavelength which exhibits a greater absorption coefficient to water than said first radiation wavelength;directing means for directing said first and second radiation wavelengths into the blood conduit;first detecting means for detecting the amount of first radiation after passing through the blood conduit, said detected amount of first radiation having at least one extinction characteristic;second detecting means for detecting the amount of second radiation after passing through the blood conduit, said detected amount of second radiation having at least one extinction characteristic; said characteristic in said detected amount of first radiation being different from the corresponding characteristic in the detected amount of second radiation;means for applying a representation of the extinction coefficient in a ratioemtric polynomial where the polynomial is related to a change in a physical parameter; andmeans for solving the polynomial to determine the first biological constituent without knowing blood volume.