Method and apparatus

• US 6,611,320 B1
• Filed: 09/07/2000
• Issued: 08/26/2003
• Est. Priority Date: 09/08/1999
• Status: Expired due to Fees

• Current Assignee: Optoq AB (Accelerator Nordic AB)
• Original Assignee: Optoq AB (Accelerator Nordic AB)
• Inventors: Lindberg, Lars-Göran, Vegfors, Magnus, Enlund, Gunnar
• Primary Examiner(s): Rosenberger, Richard A.
• Assistant Examiner(s): Barth, Vincent P
• Application Number:
  US09/657,305
• Time in Patent Office: 1,083 Days
• Field of Search: 600/323, 600/320, 600/322, 600/328, 600/368, 356/41, 356/40, 356/42, 436/66
• US Class Current: 356/40
• 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 5/14557 specially adapted to extracorporeal circuits
• CPC Class Codes: A61B 5/411 Detecting or monitoring allergy or intolerance reactions to an allergenic agent or substance
• CPC Class Codes: G01N 33/72 involving blood pigments, e.g. haemoglobin, bilirubin or other porphyrins; involving occult blood

Abstract

The present invention relates to a method for detecting blood characteristics including hemoglobin in a fluid medium using both transmission and reflection of a light beam which forms a quotient.

Claims

1. A non-invasive method for the quantitative measurement of haemoglobin concentration in relation to total blood volume in a mixture of liquid and blood cells contained in a light pervious vessel, which comprises

directing light of at least one wavelength against the vessel;

detecting the intensity of the light transmitted through the vessel;

detecting the intensity of light reflected from the vessel;

calculating a quotient of said intensity of transmitted light amd reflected light; and

analysing said quotient to determine the haemoglobin concentration.

2. The method according to claim 1, wherein the light is directed essentially perpendicular to a measuring area of the vessel, at a wavelength where absorbance on the red blood cells is minimized.

3. A method according to claim 1, wherein the wavelength of the light is from 770 nm to 950 nm.

4. A method according to claim 1, wherein light of two wavelengths is directed against the vessel, one wavelength being in an interval of from 770 nm to 950 nm and the other wavelength being in an interval of from 480 nm to 590 nm.

5. A method according to claim 1, wherein the measurement is performed on a human being.

6. A method according to claim 1, wherein the measurement is performed on a human being and the light pervious vessel is a blood vessel having a diameter >

0.1 mm, a vein, an artery or an arteriol.

7. A method according to claim 5, wherein the measurement is performed on a wrist, a toe or a finger.

8. A method according to claim 1, wherein light is emitted from two light sources, which are positioned at opposite sides of the vessel, and wherein the detection of reflected light and transmitted light is performed using two detectors.

18. A computer program stored on a data carrier, containing instructions for performing the method according to claim 1.

20. A method according to claim 7, wherein the measurement is performed on the third phalanx of a finger.

9. An apparatus for the quantitative measurement of haemoglobin concentration in relation to total blood volume in a mixture of liquid and blood cells contained in a light pervious vessel, said apparatus comprising

at least one light source for directing light of at least one, wavelength against said vessel;

a first detector for detecting the intensity of the light transmitted through said vessel;

a second detector for detecting the intensity of light reflected from said vessel;

processor for calculating a quotient of said intensity of transmitted light and reflected light; and

means for analysing said quotient to determine the haemoglobin concentration.

10. An apparatus according to claim 9, wherein said at least one light source is positioned essentially perpendicular to a measuring area of said vessel and capable of emitting light at a wavelength at which the absorbance of red blood cells is minimized.

11. An apparatus according to claim 9, wherein the wavelength of said light is from 770 nm to 950 nm.

12. An apparatus according to claim 9 wherein two light sources are present and light of two wavelengths is directed against said vessel, one wavelength being in the interval of 770 nm to 950 nm, and the other wavelength being in the interval of,480 nm to 590 nm.

13. An apparatus according to claim 9, wherein said first detector is positioned essentially opposite to said light source, and said second detector is positioned alongside said light source.

14. An apparatus according to claim 9, wherein said apparatus further comprises a thimble-like shell suitable for application to a finger or toe of a human being, said light source and detectors arranged to direct the light and to detect transmitted and reflected light within said shell.

15. An apparatus according to claim 9, wherein said apparatus further comprises a handcuff-like shell suitable for application to a wrist of a human being, said light source and arranged to direct the light and to detect transmitted and reflected light within said shell.

16. An apparatus according to claim 9, wherein said apparatus further comprises a flexible part fixing the position of and applying pressure to the vessel.

17. An apparatus according to claim 9, having two light sources arranged on opposite sides of the vessel.

19. An apparatus according to claim 9, said apparatus comprising

means for registering and storing the haemoglobin concentration values; and

means for visualizing the result of said measurement.