System for noninvasive hematocrit monitoring

• US 6,266,546 B1
• Filed: 05/28/1998
• Issued: 07/24/2001
• Est. Priority Date: 10/06/1990
• Status: Expired due to Term

• Current Assignee: Fresenius Medical Care Holdings Incorporated (Fresenius SE & Co. KGaA)
• Original Assignee: In-Line Diagnostics Corp.
• Inventors: Harris, David H., Steuer, Robert R.
• Primary Examiner(s): WINAKUR, ERIC FRANK
• Application Number:
  US09/084,958
• Time in Patent Office: 1,153 Days
• Field of Search: 600/310, 600/316, 600/322, 600/323, 600/320, 600/326, 600/328, 600/330, 600/336
• US Class Current: 600/322
• CPC Class Codes: A61B 5/14535 for measuring haematocrit
• CPC Class Codes: A61B 5/14546 for measuring analytes not otherwise provided for, e.g. ions, cytochromes
• 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 5/6816 Ear lobe
• CPC Class Codes: A61B 5/6826 Finger
• CPC Class Codes: A61B 5/6838 Clamps or clips
• CPC Class Codes: A61B 5/6843 Monitoring or controlling sensor contact pressure
• CPC Class Codes: A61M 1/361 before treatment
• CPC Class Codes: A61M 1/3612 after treatment
• CPC Class Codes: B07C 3/00 Sorting according to destination collating the pages of a book B42C1/00
• CPC Class Codes: G01N 2021/036 transformable, modifiable
• CPC Class Codes: G01N 21/0303 Optical path conditioning in cuvettes, e.g. windows; adapted optical elements or systems; path modifying or adjustment G01N21/031 - G01N21/15 take precedence

Abstract

A system for determining the hematocrit transcutaneously and noninvasively. Disclosed are a finger clip assembly and an earlobe clip assembly, each including at least a pair of emitters and a photodiode in appropriate alignment to enable operation in either a transmissive mode or a reflectance mode. At least two, and preferably three, predetermined wavelengths of light are passed onto or through body tissues such as the finger, earlobe, or scalp, etc. and the extinction of each wavelength is detected. Mathematical manipulation of the detected values compensates for the effects of body tissue and fluid and determines the hematocrit value. If a fourth wavelength of light is used which is extinguished substantially differently by oxyhemoglobin and reduced hemoglobin and which is not substantially extinguished by plasma, then the blood oxygen saturation value, independent of hematocrit, may be determined. It is also disclosed how to detect and analyze multiple wavelengths using a logarithmic DC analysis technique. Then a pulse wave is not required. So this method may be utilized in states of low blood pressure or low blood flow.

Claims

1. A system for determining a first biological constituent value of the blood of a patient, the blood having a second biological constituent different from said first biological constituent and flowing in a pulsatile fashion in a body part of the patient or in an extracorporeal passageway in communication with the circulatory system of the patient so as to be subjectable to transcutaneous examination in the body part or to noninvasive examination in the extracorporeal passageway, the body part or the extracorporeal passageway defining a blood conduit, the system comprising:

blood conduit receiving means for receiving a blood conduit containing the flowing blood of the patient;

a first emitter means positioned on said conduit receiving means for emitting a first radiation wavelength;

a second emitter means positioned on said conduit receiving means for emitting a second radiation wavelength which exhibits a greater absorption coefficient to water than said first radiation wavelength;

directing means for directing said first and second radiation wavelengths into the blood conduit;

first detecting means for detecting the amount of first radiation after passing through the blood conduit, said detected amount of first radiation having at least one extinction characteristic;

second detecting means for detecting the amount of second radiation after passing through the blood conduit, said detected amount of second radiation having at least one extinction characteristic;

said characteristic in said detected amount of first radiation being different from the corresponding characteristic in the detected amount of second radiation;

means for applying a representation of the extinction coefficient in a ratioemtric polynomial where the polynomial is related to a change in a physical parameter; and

means for solving the polynomial to determine the first biological constituent without knowing blood volume.

2. The system of claim 1, wherein said first, and second emitter means are a predetermined distance from each other.

3. The system of claim 1, wherein said first emitter means comprises two emitters.

4. The system of claim 3, wherein said second emitter means comprises two emitters.

5. The system of claim 4, wherein said first and second emitter pairs are spaced from each other.

6. The system of claim 1, wherein said first biologic constituent is hematocrit.

7. The system of claim 1, wherein said first biologic constituent is hemoglobin.

8. The system of claim 1, wherein said first biologic constituent is glucose.

9. A system for determining biological constituent value of the blood of a patient, the blood flowing in a pulsatile fashion in a body part of the patient or in an extracorporeal passageway in communication with the circulatory system of the patient so as to be subjectable to transcutaneous examination in the body part or to noninvasive examination in the extracorporeal passageway, the body part or the extracorporeal passageway defining a blood conduit and the system comprising:

blood conduit receiving means for receiving a blood conduit containing the flowing blood of the patient;

a first emitter means positioned on said conduit receiving means for emitting a first radiation wavelength;

a second emitter means positioned on said conduit receiving means for emitting a second radiation wavelength which exhibits a greater absorption coefficient to water than said first radiation wavelength;

directing means for directing said first and second radiation wavelengths into the blood conduit;

first detecting means for detecting the amount of first radiation after passing through the blood conduit, said detected amount of first radiation having at least one extinction characteristic exhibiting functional information in the form of one of a first curvature, first offset, first linearity, or a first sign;

second detecting means for detecting the amount of second radiation after passing through the blood conduit, said detected amount of second radiation having at least one extinction characteristic exhibiting functional information in the form of one of a second curvature, second offset, second linearity, or a second sign and said information in said detected amount of first radiation being different from the corresponding information in the detected amount of second radiation; and

means for mathematically manipulating the detected quantities of the first and second radiation wavelengths with a polynomial function to determine the value of a biological constituent, wherein said biologic constituent value is determined without knowing the blood volume.

10. The system of claim 9, wherein said first emitter means comprises two emitters.

11. The system of claim 10, wherein said second emitter means comprises two emitters.

12. The system of claim 11, wherein said first and second emitter pairs are spaced from each other.

13. The system of claim 9, wherein said biologic constituent is hematocrit.

14. The system of claim 9, wherein said biologic constituent is hemoglobin.

15. The system of claim 9, wherein said biologic constituent is glucose.

16. A system for determining a first biological constituent value of the blood of a patient, the blood having a second biological constituent different from said first biological constituent and flowing in a pulsatile fashion in a body part of the patient or in an extracorporeal passageway in communication with the circulatory system of the patient so as to be subjectable to transcutaneous examination in the body part or to noninvasive examination in the extracorporeal passageway, the body part or the extracorporeal passageway defining a blood conduit, the system comprising:

blood conduit receiving means for receiving a blood conduit containing the flowing blood of the patient;

a first emitter means positioned on said conduit receiving means for emitting a first radiation wavelength;

a second emitter means positioned on said conduit receiving means for emitting a second radiation wavelength which exhibits a greater absorption coefficient to water than said first radiation wavelength;

directing means for directing said first and second radiation wavelengths into the blood conduit;

first detecting means for detecting the amount of first radiation after passing through the blood conduit, said detected amount of first radiation having at least one extinction characteristic;

second detecting means for detecting the amount of second radiation after passing through the blood conduit, said detected amount of second radiation having at least one extinction characteristic;

said characteristic in said detected amount of first radiation being different from the corresponding characteristic in the detected amount of second radiation;

means for forming for each wavelength the ratio of a change in a physical parameter over time to the value of the physical parameter; and

means for mathematically manipulating the formed ratio with a polynomial function, wherein the value of the first biological constituent is determined without knowing blood volume.

17. The system of claim 16 wherein the parameter is light intensity.

18. The system of claim 16 wherein the parameter is distance.

19. The system of claim 16 wherein the parameter is time.

20. A system for determining a first biological constituent value of the blood of a patient, the blood having a second biological constituent different from said first biological constituent and flowing in a pulsatile fashion in a body part of the patient or in an extracorporeal passageway in communication with the circulatory system of the patient so as to be subjectable to transcutaneous examination in the body part or to noninvasive examination in the extracorporeal passageway, the body part or the extracorporeal passageway defining a blood conduit, the system comprising:

blood conduit receiving means for receiving a blood conduit containing the flowing blood of the patient;

a first emitter means positioned on said conduit receiving means for emitting a first radiation wavelength;

a second emitter means positioned on said conduit receiving means for emitting a second radiation wavelength which exhibits a greater absorption coefficient to water than said first radiation wavelength;

directing means for directing said first and second radiation wavelengths into the blood conduit;

first detecting means for detecting the amount of first radiation after passing through the blood conduit, said detected amount of first radiation having at least one extinction characteristic;

second detecting means for detecting the amount of second radiation after passing through the blood conduit, said detected amount of second radiation having at least one extinction characteristic;

said characteristic in said detected amount of first radiation being different from the corresponding characteristic in the detected amount of second radiation;

means for forming for each wavelength a ratio of a change in transmitted intensity over time to the transmitted intensity;

means for differentially subtracting the formed ratio at the first wavelength from the formed ratio at the second wavelength; and

means for mathematically manipulating the differentially subtracted ratio with a polynomial function, wherein the value of the first biological constituent is determined without knowing blood volume.