Blood hematocrit monitoring system

• US 4,243,883 A
• Filed: 01/19/1979
• Issued: 01/06/1981
• Est. Priority Date: 01/19/1979
• Status: Expired due to Term

• Current Assignee: Midwest Cardiovascular Institute Foundation
• Original Assignee: Midwest Cardiovascular Institute Foundation
• Inventors: Schwarzmann, Frank
• Primary Examiner(s): Lieberman, Eli
• Assistant Examiner(s): Fields, Carolyn E.
• Application Number:
  US06/004,758
• Time in Patent Office: 718 Days
• Field of Search: 356/40, 356/39, 356/41, 250/343, 128/633, 128/214 R, 128/214 E, 23/913, 422/44, 422/45
• US Class Current: 250/343
• CPC Class Codes: G01N 21/85 Investigating moving fluids or granular solids

Abstract

A system for continuously monitoring and/or controlling blood hematocrit levels is disclosed. The system includes a photometric hematocrit sensor which is coupled to a linear response meter, and in one embodiment a separate sensor is coupled to a three-way solenoid valve. The sensor is responsive to the hemoglobin density in the optical path. The valve system automatically causes diversion of solution having a degree of hematocrit dilution below a set minimum. The sensor is independent of the amount of oxy-hemoglobin (HbO₂) and reduced hemoglobin (HHb) and the system allows for instantaneous detection of improper hematocrit levels and obviates the need for time-consuming and unreliable centrifugal micro-hematocrit tests.

Claims

1. A system for monitoring and controlling the level of blood hematocrit comprising:

an infra-red light source means;

an infra-red sensitive photo-transistor detector means opposing said light source means, said detector means being selected so as to produce a change in voltage dependent upon the amount of light impinging thereupon and having a spectral sensitivity at the wavelength of the light source means;

lumen means intermediate said light source means and said detector means, said lumen means being substantially optically transparent to the light emitted by said light source means; and

meter means responsive to the voltage emitted from said detector means for indicating the quantity of hematocrit within a moving column of blood when said column is passed through said lumen means;

a three-way valve means downstream of said detector means and said light source means, said valve means being coupled to said lumen means, a first outlet of said valve means and a second outlet from said valve means; and

means within said meter means for causing blood to flow from said lumen means to said first outlet when the blood hematocrit level is above a preselected value and to flow from said lumen to said second outlet when the blood hematocrit level is below said preselected value.

2. The device set forth in claim 1 wherein the maximum spectral output of the light source means and the maximum sensitivity of said detector are at approximately the same wavelength.

3. The device set forth in claim 2 wherein said wavelength is approximately 800 nm.

4. The device set forth in claim 1 wherein said light source means, detector means and lumen means are contained within a sensor housing adapted for preventing extraneous light from reaching the area between said light source means and detector means.

5. The device set forth in claim 1 wherein said housing means is interiorly coated with a non-reflective coating

6. The invention set forth in claim 1 wherein said lumen means is contructed of plastic and includes optically transparent glass windows at the area of said lumen means disposed between said light source means and said detector means.

7. The invention set forth in claim 1 wherein said meter means is a linear response meter.

8. The invention set forth in claim 1 wherein said valve means is a solenoid valve.

9. A device for monitoring the level of blood hematocrit in a moving blood column comprising:

a lumen for containing said column of blood, at least a portion of said lumen being optically transparent to light passing therethrough at a wavelength of approximately 800 nm;

a light source disposed adjacent said portion of said lumen for directing light having a wavelength of approximately 800 nm through said lumen;

a photo-transistor detector disposed on the opposite side of said portion of said lumen for receiving light from said light source and having a maximum spectral sensitivity at approximately 800 nm;

meter means coupled to said detector for indicating the quantity of hematocrit within said lumen;

a three-way valve means downstream of said detector means and said light source means coupled to said lumen means, a first outlet of said valve means and a second outlet from said valve means; and

means within said meter means for causing blood to flow from said lumen to said first outlet when the blood hematocrit level is above a preselected value and to flow from said lumen to said second outlet when the blood hematocrit is below said preselected value.

10. A device for monitoring the level of blood hematocrit in a moving column of blood comprising:

an infra-red light source means;

an infra-red sensitive photo-transistor detector means opposing said light source means, said detector being selected so as to produce a change in voltage dependent upon the amount of light impinging thereupon and having a spectral sensitivity at the wavelength of the light source means;

housing means containing said light source and detector means;

tube means for conveying blood to said housing and away therefrom;

lumen means within said housing and disposed intermediate said light source and detector means, said lumen means being coupled at each end to said tube means and having a pair of parallel optically transparent window means at the portion of said lumen means intermediate said light source and detector means;

locating means on the exterior of said lumen means and means within said housing for engaging said locating means whereby said lumen means is located within said housing means only in a position where the light emitted from said light source is directed perpendicularly through said window means toward said detector means; and

meter means coupled to said detector means and being responsive to the voltage emitted from said detector means for indicating the quantity of hematocrit within a moving column of blood when said column is passed through said lumen means.

11. The device set forth in claim 10 wherein said locating means comprises a plurality of lugs located on the exterior surface of said lumen means and adapted for engaging mating receptacles within said housing means.