Non-Invasive Measurement Device and Method for Estimating Local Metabolic Parameters
First Claim
1. A method for estimating at least one local metabolic parameter of a tissue area of a patient, wherein the method comprises the following steps:
- Reception of measured light intensities for the relevant tissue area, said light intensities being measured by an acquisition device for at least three different wavelengths comprised between 600 and 1000 nm, said wavelengths being selected as a function of the absorptivity of different types of hemoglobin, such as oxyhemoglobin and deoxyhemoglobin, the reception step consisting of receiving, for each wavelength, a plurality of measured light intensities at different instants of a heartbeat period,Selection, for each wavelength, of measured light intensities at at least one instant of the cardiac cycle for which the aim is to estimate said and at least one local metabolic parameter, said selection step consisting of selecting, from all the measured light intensities, light intensities for which the amount of arterial blood is minimum in the relevant tissue area such that the determined concentrations are representative of concentration of oxyhemoglobin and deoxyhemoglobin in the venous blood,Calculation, from selected light intensities, of absorbance values for the three wavelengths,Determination, from absorbance values calculated for the three wavelengths;
of a concentration of oxyhemoglobin,of a concentration of deoxyhemoglobin,given the tissue absorbance in the estimation of concentrations of oxyhemoglobin and deoxyhemoglobin,Estimation of at least one local metabolic parameter from concentrations of calculated oxyhemoglobin and deoxyhemoglobin.
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Abstract
The invention relates to a method for estimating a local metabolic parameter of an area of tissue of a patient, said method comprising: receiving (10) light intensities from the area of tissue in question for at least three different wavelengths selected according to the absorptive power of different types of haemoglobin; on the basis of the absorbancy values calculated using the light intensities measured for the three wavelengths, determining (40) a oxyhaemoglobin concentration and a deoxyhaemoglobin concentration; and estimating (50) at least one local metabolic parameter on the basis of the calculated oxyhaemoglobin and deoxyhaemoglobin concentrations.
12 Citations
18 Claims
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1. A method for estimating at least one local metabolic parameter of a tissue area of a patient, wherein the method comprises the following steps:
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Reception of measured light intensities for the relevant tissue area, said light intensities being measured by an acquisition device for at least three different wavelengths comprised between 600 and 1000 nm, said wavelengths being selected as a function of the absorptivity of different types of hemoglobin, such as oxyhemoglobin and deoxyhemoglobin, the reception step consisting of receiving, for each wavelength, a plurality of measured light intensities at different instants of a heartbeat period, Selection, for each wavelength, of measured light intensities at at least one instant of the cardiac cycle for which the aim is to estimate said and at least one local metabolic parameter, said selection step consisting of selecting, from all the measured light intensities, light intensities for which the amount of arterial blood is minimum in the relevant tissue area such that the determined concentrations are representative of concentration of oxyhemoglobin and deoxyhemoglobin in the venous blood, Calculation, from selected light intensities, of absorbance values for the three wavelengths, Determination, from absorbance values calculated for the three wavelengths; of a concentration of oxyhemoglobin, of a concentration of deoxyhemoglobin, given the tissue absorbance in the estimation of concentrations of oxyhemoglobin and deoxyhemoglobin, Estimation of at least one local metabolic parameter from concentrations of calculated oxyhemoglobin and deoxyhemoglobin. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
at the absorbance values calculated at said and at least three wavelengths as a function of molar absorptivity values for said and at least three wavelengths.
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8. The method according to claim 7, wherein the determination step comprises resolution of a following system:
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9. The method according to claim 1, wherein the determination step comprises resolution of a system of equations by a regularised optimisation method.
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10. A computer program product comprising program code recorded on a data medium readable by a computer for executing the method according to claim 1 when the computer program is applied to a computer to be executed.
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11. A device for estimating at least one local metabolic parameter of a tissue area of a patient, characterized in that it comprises a processing unit programmed to perform the steps of the method according to claim 1.
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12. The method according to claim 5, wherein the first wavelength is comprised between 600 and 700 nm.
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13. The method according to claim 12, wherein the first wavelength is equal to 660 nm.
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14. The method according to claim 5, wherein the second wavelength is comprised between 900 and 1000 nm.
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15. The method according to claim 14, wherein, wherein the second wavelength is equal to 906 nm.
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16. The method according to claim 5, wherein the third wavelength is comprised between 796 nm and 810 nm.
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17. The method according to claim 16, wherein the third wavelength is equal to 810 nm.
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18. The method according to claim 6, wherein the fourth wavelength is equal to 750 nm.
Specification