Non-invasive determination of the concentration of a blood substance

An arrangement for determining concentration of a substance in blood of a subject, the arrangement comprising:

• a first determination unit configured to store an a priori relationship indicative of the effect of tissue on in-vivo measurement signals at at least three wavelengths, wherein the in-vivo measurement signals are indicative of absorption caused by blood of a subject;
• a measurement unit configured to acquire the in-vivo measurement signals from in-vivo tissue at the at least three wavelengths;
• a second determination unit configured to determine, based on the a priori relationship, a specific value of a tissue parameter for which the effect of the in-vivo tissue on the in-vivo measurement signals is consistent for the at least three wavelengths, the specific value representing concentration of a substance in the blood of the subject;
• and
• a display unit for presenting the specific value as the determined concentration of the substance in blood of the subject.

An apparatus for determining concentration of a substance in blood of a subject, the apparatus comprising:

• an interface unit configured to download an a priori relationship indicative of the effect of tissue on in-vivo measurement signals at at least three wavelengths, wherein the in-vivo measurement signals are indicative of absorption caused by blood of a subject;
• a signal reception unit configured to receive in-vivo measurement signals acquired from in-vivo tissue at the at least three wavelengths;
• and
• a determination unit configured to determine, based on the a priori relationship, a specific value of a tissue parameter for which the effect of the in-vivo tissue on the in-vivo measurement signals is consistent for the at least three wavelengths, the specific value representing concentration of a substance in the blood of the subject.

A non-transitory computer program product embodied on a tangible medium of expression for determining concentration of a substance in blood of a subject, the computer program product comprising:

• a first program product portion configured to receive an a priori relationship indicative of the effect of tissue on in-vivo measurement signals at at least three wavelengths, wherein the in-vivo measurement signals are indicative of absorption caused by blood of a subject;
• a second program product portion configured to receive in-vivo measurement signals acquired from in-vivo tissue at the at least three wavelengths;
• and
• a third program product portion configured to determine, based on the a priori relationship, a specific value of a tissue parameter for which the effect of the in-vivo tissue on in-vivo measurement signals is consistent for the at least three wavelengths, the specific value representing concentration of a substance in the blood of the subject.