Importance

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Abstract

The invention relates to a procedure for determining the relative concentration or composition of different kinds of haemoglobin, such as oxyhaemoglobin, deoxyhaemoglobin and dyshaemoglobins, and/or dye components contained in blood in a non-invasive manner using the light absorption caused by different haemoglobin varieties and/or dye components, in which procedure light signals are transmitted at at least two predetermined wavelengths to a tissue comprised in the patient's blood circulation, the light signal transmitted through the target under measurement and/or reflected from it is received and the proportion of the intensity of the pulsating light signal received at each wavelength is determined in relation to the total intensity of the light transmitted through the tissue or reflected from the tissue. In the procedure, the effective extinction coefficients of blood haemoglobin derivatives and/or dye components in the tissue are determined for each light signal and/or light signal pair via a mathematical transformation from blood dye component extinction coefficients consistent with the Lambert-Beer theory and the proportion of specific blood haemoglobin derivatives and/or dye components in relation to the total amount of haemoglobin contained in the blood is determined by means of the intensity of the signals received in different wavelength ranges.

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First Claim