Single light sensor optical probe for monitoring blood parameters and cardiovascular measurements

• US 6,493,567 B1
• Filed: 03/20/2000
• Issued: 12/10/2002
• Est. Priority Date: 10/14/1997
• Status: Expired due to Fees

• Current Assignee: Transonic Systems, Inc. (Measurement Innovations Corp.)
• Original Assignee: Transonic Systems, Inc. (Measurement Innovations Corp.)
• Inventors: Starostin, Dimitry, Krivitski, Nikolai M.
• Primary Examiner(s): WINAKUR, ERIC FRANK
• Application Number:
  US09/528,880
• Time in Patent Office: 995 Days
• Field of Search: 600/310, 600/320, 600/322, 600/323, 604/65, 604/67, 356/39, 356/441, 356/442, 356/432, 250/343
• US Class Current: 600/322
• CPC Class Codes: A61B 5/0275 using tracers, e.g. dye dilution
• CPC Class Codes: A61B 5/029 Measuring or recording blood output from the heart, e.g. minute volume A61B8/065 takes precedence
• CPC Class Codes: A61B 5/14557 specially adapted to extracorporeal circuits
• CPC Class Codes: A61M 1/1615 using measurements made at different flow rates
• CPC Class Codes: A61M 1/1617 using measurements made during a temporary variation of a characteristic of the fresh dialysis fluid
• CPC Class Codes: A61M 1/361 before treatment
• CPC Class Codes: A61M 1/3612 after treatment

Abstract

A method and device for the continuous real-time monitoring of relative blood volume change, based on registration of blood hemoglobin concentration, during long periods of time, such as dialysis session. A method and device for cardiac output measurement, based on optical dilution technique, during dialysis, surgeries, intensive care procedure. The effects of blood electrolyte composition change which result in a change of light beam geometry are eliminated by the relative orientation between a light source and a single light or photodetector. An illumination axis and a detection axis are oriented in an offset, non collinear configuration at a sufficient angle to substantially eliminate the scattering properties of the blood. A primary implementation of the device is extracorporeal paths, such as hemodialysis tubing systems, artery-vein extracorporeal artificial shunts, other extracorporeal systems. It also may be applied to vessels, tissues or to body parts being capable of transillumination.

Claims

1. A method for determining blood parameters, comprising:

(a) directing a light beam along an illumination vector into a blood column; and

(b) measuring the light emerging from the blood column along a detection vector, the detection vector inclined to the illumination vector by a sufficient angle to substantially eliminate an influence of light scattering in the blood resulting from one of blood electrolyte composition, blood flow rate and blood hematocrit or hemoglobin levels.

2. The method of claim 1, further comprising locating a light port passing the illumination vector and a detector port passing the detection vector at a common longitudinal position along the blood column.

3. The method of claim 1, further comprising locating a light port passing the illumination vector at a first longitudinal position along the blood column and a detector port passing the detection vector at a second different longitudinal position along the blood column.

5. The method of claims 1 or 2, further comprising determining a relative change in blood hemoglobin concentration.

6. The methods of claims 1 or 2, further comprising determining a relative change in circulating blood volume.

7. The methods of claims 1 or 2, further comprising determining a cardiac output of a patient.

8. The method of claim 2, further comprising locating a detector port passing the second axis and a light port passing the first axis at a common longitudinal position along the blood column.

9. The method of claim 2, further comprising locating a light port passing the first axis at a first longitudinal position along the blood column and a detector port passing the second axis at a different second longitudinal position along the blood column.

4. A method for determining blood parameters, comprising:

(a) directing a light beam along a first axis into a blood column;

(b) operably locating a photodetector on a second axis, the second axis defining an angle between the first axis and the second axis sufficient to substantially eliminate an influence of light scattering in the blood column along the second axis induced by one of blood electrolyte composition, blood flow rate and blood hematocrit or hemoglobin levels; and

(c) detecting and measuring the light emerging from the blood along the second axis.

10. A method of measuring a blood property comprising projecting an isobestic light wave length through a blood column and detecting a light emerging from the blood column to substantially eliminate error induced by variations in oxygen saturation of a blood hemoglobin.

11. A device for optically determining blood properties, comprising:

(a) a light beam source directable into a blood column through a light beam port;

(b) a single detector for registering blood light and light intensity changes in light emerging from the blood column; and

(c) a housing to locate the detector relative to the light beam port to register a received light signal substantially independent of scattering properties of the blood column.

14. The device of claims 11 or 13, wherein the light beam port and the detector are located at a common longitudinal location in the blood column.

15. The device of claims 11 or 13, wherein the housing is configured to locate a length of extracorporeal tubing intermediate the light beam port and the detector.

16. The device of claims 11, 12 or 13, further comprising a tubing for containing the blood column.

17. The device of claims 11 or 13, wherein a distance between the light beam port and the detector is constant.

18. The devices of claims 11, 12 or 13, wherein the light beam source produces a light of known intensity and an isobestic wavelength.

19. The devices of claims 11 or 13, wherein the light beam port is located at a first longitudinal position along the blood column and the detector is located at a different second longitudinal position along the blood column.

12. A device for optically determining blood properties, comprising:

(a) a light beam source selected to direct a light beam into a blood column along an illumination vector; and

(b) a single detector for registering blood light and light intensity changes in light emerging from the blood column along a detection vector;

the illumination vector intersecting the detection vector at an angle to substantially minimize dependence of the registered blood light and light intensity changes on scattering properties of the blood column.

13. A device for optically determining blood properties, comprising:

(a) a light beam source directing a light beam through a light beam port into a blood column;

(b) a single detector for registering a light intensity change in light emerging from the blood column; and

(c) a housing for retaining the detector relative to the light beam port to register the emerging light substantially independent of scattering properties of the blood.

20. A method for determining blood parameters, comprising:

(a) directing a light beam along an illumination vector into a blood column; and

(b) measuring the light emerging from the blood column along a detection vector, the detection vector inclined to the illumination vector by a sufficient angle to measure light scattering in the blood resulting from one of blood electrolyte composition, blood flow rate and blood hematocrit or hemoglobin levels.

21. A method for determining blood parameters, comprising:

(a) directing a light beam along a first axis into a blood column;

(b) operably locating a photodetector on a second axis, the second axis defining an angle between the first axis and the second axis sufficient to identify an influence of light scattering in the blood column along the second axis induced by one of blood electrolyte composition, blood flow rate or blood hematocrit or hemoglobin levels; and

(c) detecting and measuring the light emerging from the blood column along the second axis.