Method and system for use in non-invasive optical measurements of blood parameters

• US 20060129040A1
• Filed: 01/30/2006
• Published: 06/15/2006
• Est. Priority Date: 06/03/2003
• Status: Active Grant

• Current Assignee: OrSense Ltd.
• Original Assignee: OrSense Ltd.
• Inventors: Fine, Ilya, Finarov, Alexander
• Granted Patent: US 7,386,336 B2
• Time in Patent Office: Days
• US Class Current: 600/335
• CPC Class Codes: A61B 5/0059 using light, e.g. diagnosis by transillumination, diascopy, fluorescence A61B5/0093, A61B5/1455, A61B5/02416 and A61B5/0261 take precedence
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor
• CPC Class Codes: A61B 5/6826 Finger
• CPC Class Codes: A61B 5/6838 Clamps or clips

Abstract

A method and device are presented for use in non-invasive optical measurements of at least one desired characteristic of patient'"'"'s blood. A condition of artificial blood kinetics is created at a measurement location in a patient'"'"'s blood perfused fleshy medium and maintained for a certain time period. This condition is altered over a predetermined time interval within said certain time period so as to modulate scattering properties of blood. Optical measurements are applied to the measurement location by illuminating it with incident light beams of at least two different wavelengths in a range where the scattering properties of blood are sensitive to light radiation, detecting light responses of the medium, and generating measured data indicative of time evolutions of the light responses of the medium for said at least two different wavelengths, respectively, over at least a part of said predetermined time interval.

Claims

11. A method for use in non-invasive optical measurements of at least one desired characteristic of patient'"'"'s blood, the method comprising:

(a) creating a condition of artificial blood kinetics at a measurement location in a patient'"'"'s blood perfused fleshy medium and maintaining this condition for a certain time period, the creation of the artificial blood kinetics comprising applying primary over-systolic pressure to achieve a state of temporary blood flow cessation in the medium at the measurement location, the primary over-systolic pressure being applied to either a certain location upstream of the measurement location with respect to a normal blood flow direction in the medium or to the vicinity of the measurement location;

(b) altering said condition of artificial blood kinetics at the measurement location over a predetermined time interval within said certain time period so as to modulate scattering properties of blood, said altering of the condition of artificial blood kinetics including applying perturbations to the medium by secondary pressure of a predetermined cyclic pattern over said predetermined time interval; and

(c) applying optical measurements to the measurement location by illuminating it with incident light beams of at least two different wavelengths in a range where the light radiation is sensitive to scattering properties of blood, detecting light responses of the medium, and generating measured data indicative of time evolutions of the light responses of the medium for said at least two different wavelengths, respectively, over at least a part of said predetermined time interval.

1. A method for use in non-invasive optical measurements in a patient'"'"'s body, the method comprising:

(a) creating a condition of artificial blood kinetics at a measurement location in a patient'"'"'s blood perfused fleshy medium and maintaining this condition for a certain time period, the creation of the artificial blood kinetics comprising applying primary over-systolic pressure to achieve a state of temporary blood flow cessation in the medium at the measurement location, the primary over-systolic pressure being applied to either a certain location upstream of the measurement location with respect to a normal blood flow direction in the medium or to the vicinity of the measurement location;

(b) altering said condition of artificial blood kinetics at the measurement location over a predetermined time interval within said certain time period so as to modulate optical response by changing scattering properties of blood, said altering of the condition of artificial blood kinetics including applying a perturbation to the medium by at least one secondary pressure pulse of a predetermined value over said predetermined time interval; and

(c) applying optical measurements to the measurement location by illuminating it with incident light beams of at least two different wavelengths in a range where the light radiation is sensitive to scattering properties of blood, detecting light responses of the medium, and generating measured data indicative of time evolutions of the light responses of the medium for said at least two different wavelengths, respectively, over at least a part of said predetermined time interval.

2. The method of claim 1, comprising:

analyzing the measured data for determined a parameter derived from scattering spectral features of the medium as a relation between the different time evolutions of the light responses of the medium; and

utilizing the calculated parameter and predetermined reference data, created during a calibration procedure and being indicative of the desired blood characteristic as a function of the parameter derived from scattering spectral features of the medium, thereby enabling determining a value of the desired blood characteristic.

3. The method of claim 2 wherein said reference data is a calibration curve defining a dependence of the parameter on the desired blood characteristic.

4. The method of claim 2 wherein said parameter is a parametric slope defined as a ratio between a first function depending on a light response of the medium corresponding to one wavelength and a second function depending on the light response of the medium corresponding to another wavelength, said one wavelength and another wavelength being selected from said at least two different wavelengths.

5. The method of claim 4 wherein said first and second functions are logarithmic functions of the light response corresponding to said at least two different wavelengths, respectively.

6. The method of claim 4 wherein said first and second functions are a time rate of the changes of light response signal.

9. The method of claim 1, wherein said certain time period is insufficient for irreversible changes in the fleshy medium.

8. The method of claim 1 wherein the predetermined value of the secondary pressure is in the range from zero to over-systolic pressure higher than said primary over-systolic pressure value.

19. The method of claim 1 wherein the predetermined value of the secondary pressure is in the range starting from said primary over-systolic pressure value.

10. The method of claim 1 wherein said altering of the condition of artificial blood kinetics includes applying perturbations to the medium by secondary pressure of a predetermined cyclic pattern over said predetermined time interval.

12. The method of claim 11 wherein said altering of the condition of artificial blood kinetics includes applying the perturbation to the medium by at least one secondary pressure pulse of a predetermined value over said predetermined time interval.

13. The method of claim 11 wherein said predetermined cyclic pattern is in the form of secondary pressure pulses having amplitudes in the range from zero to over-systolic pressure higher than said primary over-systolic pressure.

14. The method of claim 11 wherein said predetermined cyclic pattern is in the form of secondary pressure pulses having amplitudes in the range starting from said primary over-systolic pressure.

15. The method of claim 11, wherein said at least two different wavelengths are in the red-NIR range.

16. The method according to claim 11, wherein said at least one desired characteristic of patient'"'"'s blood is selected from the following:

concentration of a substance in patient'"'"'s blood, oxygen saturation, Erythrocyte Sedimentation Rate (ESR) and Erythrocyte Aggregation Rate (EAR).

17. The method according to claim 16 wherein said substance is selected from glucose and hemoglobin.

18. The method of claim 11, comprising:

analyzing the measured data for determined a parameter derived from scattering spectral features of the medium as a relation between the different time evolutions of the light responses of the medium; and

utilizing the calculated parameter and predetermined reference data, created during a calibration procedure and being indicative of the desired blood characteristic as a function of the parameter derived from scattering spectral features of the medium, thereby enabling determining a value of the desired blood characteristic

19-1. The method of claim 18 wherein said reference data is a calibration curve defining a dependence of the parameter on the desired blood characteristic.

20. A probe for use in non-invasive optical measurements in a human body, the probe being configured as a ring mountable onto a patient'"'"'s finger so as to enclose and hold a portion of a patient'"'"'s blood perfused flesh medium between two semi-ring portions of the ring, at least one of the semi-ring portions carrying a measuring unit operable for illuminating a measurement location on the portion of the medium with incident light beams, detecting light responses of the medium, and generating measured data indicative of time evolutions of the light responses, said semi-ring portions being controllably driven to move one towards the other to thereby apply over-systolic pressure to the fleshy medium so as to create a condition of artificial blood kinetics in the fleshy medium and maintain this condition for a certain time period.