Compensation of human variability in pulse oximetry
First Claim
1. A method for compensating for subject-specific variability in an apparatus intended for non-invasively determining the amount of at least two light-absorbing substances in the blood of a subject and provided with emitter means for emitting radiation at a minimum of two different wavelengths and with detector means for receiving the radiation emitted, the method comprising the steps ofcalibrating the apparatus using a nominal calibration, carrying out initial characterization measurements, said measurements to include measuring radiation emitted by said emitter means and received by the detector means without transmission through tissue, based on the characterization measurements, establishing nominal characteristics describing conditions under which the nominal calibration is used, storing reference data indicating the nominal characteristics established, performing in-vivo measurements on living tissue, wherein radiation emitted by the emitter means through the living tissue and received by the detector means is measured, based on the in-vivo measurements and the reference data stored, determining tissue-induced changes in the nominal characteristics, and compensating for subject-specific variation in the in-vivo measurements by correcting the nominal calibration on the basis of the tissue-induced changes.
1 Assignment
0 Petitions
Accused Products
Abstract
The invention relates to the calibration of a pulse oximeter intended for non-invasively determining the amount of at least two light-absorbing substances in the blood of a subject. In order to bring about a solution by means of which the effects caused by the tissue of the subject can be taken into account in connection with the calibration of a pulse oximeter, initial characterization measurements are carried out for a pulse oximeter calibrated under nominal conditions. Based on the characterization measurements, nominal characteristics are established describing the conditions under which nominal calibration has been defined, and reference data indicating the nominal characteristics are stored. In-vivo measurements are then performed on living tissue and based on the in-vivo measurements and the reference data stored, tissue-induced changes in the nominal characteristics are determined. Subject-specific variation in the in-vivo measurements is compensated for by correcting the nominal calibration on the basis of the tissue-induced changes.
208 Citations
23 Claims
-
1. A method for compensating for subject-specific variability in an apparatus intended for non-invasively determining the amount of at least two light-absorbing substances in the blood of a subject and provided with emitter means for emitting radiation at a minimum of two different wavelengths and with detector means for receiving the radiation emitted, the method comprising the steps of
calibrating the apparatus using a nominal calibration, carrying out initial characterization measurements, said measurements to include measuring radiation emitted by said emitter means and received by the detector means without transmission through tissue, based on the characterization measurements, establishing nominal characteristics describing conditions under which the nominal calibration is used, storing reference data indicating the nominal characteristics established, performing in-vivo measurements on living tissue, wherein radiation emitted by the emitter means through the living tissue and received by the detector means is measured, based on the in-vivo measurements and the reference data stored, determining tissue-induced changes in the nominal characteristics, and compensating for subject-specific variation in the in-vivo measurements by correcting the nominal calibration on the basis of the tissue-induced changes.
Specification