Method and apparatus for determination of pH pCO2, hemoglobin, and hemoglobin oxygen saturation

• US 6,694,157 B1
• Filed: 02/09/1999
• Issued: 02/17/2004
• Est. Priority Date: 02/10/1998
• Status: Expired due to Fees

• Current Assignee: Daedalus I, LLC
• Original Assignee: Daedalus I, LLC
• Inventors: Stone, Robert T., Sterling, Bernhard B.
• Primary Examiner(s): WINAKUR, ERIC FRANK
• Application Number:
  US09/247,681
• Time in Patent Office: 1,834 Days
• Field of Search: 600/310, 600/322, 600/323, 600/473, 600/476, 356/39, 356/40, 356/41, 356/300, 356/317, 356/320
• US Class Current: 600/310
• CPC Class Codes: A61B 5/14539 for measuring pH
• CPC Class Codes: A61B 5/14557 specially adapted to extracorporeal circuits

Abstract

This invention relates to a method and apparatus for in-vivo, real time measurement of pH, pCO₂, base excess, hemoglobin, and hemoglobin oxygen saturation. Specifically, the invention relates to an apparatus placed in-line with an existing invasive patient access line to provide continuous, semi-continuous, or non-continuous monitoring of blood pH, pCO₂, base excess, hemoglobin, and hemoglobin oxygen saturation in a manner which is relatively non-invasive. Further, the device and apparatus allows monitoring of the listed parameters in a non-destructive manner such that the blood sample under analysis can be returned to the patient.

Claims

1. Apparatus for use in measuring molecular constituents of a sample of light dispersive fluids comprising:

a housing having an optically transmissive chamber for receiving a sample of light dispersive fluid;

first and second light sources respectively having first and second narrow bands of wavelengths, said first and second light sources being oriented to illuminate a sample in the chamber when the light sources are transmitting light;

a first and second sensors adapted to respectively detect the first and second narrow bands of wavelengths; and

a diffuser including an optically transmissive material containing a dispersion of non-absorptive light-scattering particles disposed between the sample and at least one of the light sources, and adapted to diffuse the light from said at least one of said light sources incident on the sample;

said first and second narrow bands of wavelengths and said first and second sensors being respectively selected to detect pH and pCO2 of such sample.

2. Apparatus for use in measuring molecular constituents of a sample of whole blood comprising:

a housing having an optically transmissive chamber for receiving a sample of light dispersive fluid;

first and second light sources respectively having first and second narrow bands of wavelengths, said first and second light sources being oriented to illuminate a sample in the chamber when the light sources are transmitting light;

first and second sensors adapted to respectively detect the first and second narrow bands of wavelengths; and

a diffuser including an optically transmissive material containing a dispersion of non-absorptive light-scattering particles disposed between the sample and at least one of the light sources and adapted to diffuse the light from said at least one of said light sources incident on the sample;

the first and second narrow bands of wavelengths and said first and second sensors being respectively selected for the determination of hemoglobin concentration and/or hemoglobin oxygen saturation in said sample.

3. Apparatus for use in measuring molecular constituents of a sample of whole blood comprising:

a housing having an optically transmissive chamber for receiving a sample of light dispersive fluid;

first and second light sources respectively having first and second narrow bands of wavelengths, said first and second light sources being oriented to illuminate a sample in the chamber when the light sources are transmitting light;

first and second sensors adapted to respectively detect the first and second narrow bands of wavelengths; and

a diffuser including an optically transmissive material containing a dispersion of non-absorptive light-scattering particles disposed between the sample and at least one of the light sources and adapted to diffuse the light from said at least one of said light sources incident on the sample;

the first and second narrow band wavelengths and said first and second sensors being respectively selected for the determination of one or more of the molecular constituents selected from the group consisting of oxyselected hemoglobin, deoxygenated hemoglobin, carboxyhemoglobin, methemoglobin, or hemoglobincyanide of said sample.

4. An indicator arrangement comprising at least two narrow band light sources, optical diffusers, diffusing cuvette and light detector for determination of molecular constituents of light dispersing fluids, the improvement comprising providing an indication that is insensitive to the light scattering effects of suspended particles.

5. An indicator arrangement as defined in claim 4 wherein said measurement system is effected by means of a light measurement system including a light source, diffuse optical system, a light receiver and readout means.

6. An indicator arrangement as defined in claim 4 wherein said measurement is effected by means of one or more light emitting diodes selected for determination of the hemoglobin concentration in whole blood.

7. An indicator arrangement as defined in claim 4 wherein said measurement is effected by one or more optional filters selected for determination of the hemoglobin concentration in whole blood.

8. An indicator arrangement as defined in claim 4 wherein said measurement is effected by two or more light sources whose wavelengths are selected for determination of oxyselected hemoglobin, dioxygenated hemoglobin, carboxyhemoglobin, methemoglobin, or hemiglobincyanide.

9. An indicator arrangement as defined in claim 4 further comprising a disposable cuvette.

10. An apparatus for use in providing in-vivo, real time measurement of blood pH, pCO2, hemoglobin, and hemoglobin oxygen saturation, comprising:

a disposable cuvette having an optically transmissive housing containing first, second, and third blood chambers and first and second sensors for measurement of pH, pCO2, hemoglobin, and hemoglobin oxygen saturation;

first and second light sources respectively having first and second narrow band of wavelengths, said first and second light sources being oriented to illuminate the first and second sensors for sensing of pH and pCO2 in the first and second blood chambers, respectively; and

third and fourth light sources respectively having third and fourth narrow band of wavelengths, respectively, said third and fourth light sources being oriented to illuminate a blood sample in the third blood chamber when the third and fourth light sources are transmitting light;

means for detecting the first, second, third, and fourth narrow band of wavelengths from each of the first, second, third, and fourth light sources; and

diffuser means for providing the light illuminating the first, second, and third blood chambers with a broad angular dispersion so that the light incident on the blood samples approaches a diffuse planar source of light, the diffuser means being disposed between the light sources and the blood sample.

11. The apparatus of claim 10 wherein the diffuser means further comprises an optically transmissive material containing a dispersion of non-absorption light-scattering particles.

12. An apparatus for use in providing in-vivo, real time measurement of selected blood characteristics, comprising:

a housing containing at least one optically transmissive blood chamber for receiving a sample of blood;

at least two light sources, each providing illumination within a narrow band of wavelengths, each of said light sources being oriented to illuminate first and second sensor assemblies for detecting pH and pCO2 of a blood sample in said blood chamber when the light sources are transmitting light, wherein the first and second sensor assemblies include pH and pCO2 sensitive hydrogel layers, reflective layers, opaque layers, and appropriate blood contact layers.

13. An apparatus for use in providing in-vivo, real time measurement of blood pH, pCO2, hemoglobin, and hemoglobin oxygen saturation, comprising:

a general purpose computing device for displaying various measured values, user controls and for storing the operating instructions for the apparatus;

a first interface card containing the electronic control and signal conditioning circuitry;

a second interface card for providing connection of the computing device to analog signals and digital signals for controlling the apparatus;

a spectrophotometer providing specific wavelength visible and infra-red light sources and light intensity detection sensors;

a cuvette for introduction of blood for analysis containing the pH and pCO2 sensors; and

connective inlet and outlet tubing for introduction of the blood sample from invasive patient monitoring lines into the cuvette and for return of the blood sample to the patient

a diffuser disposed between the sample and at least one of the light sources adapted to diffuse the light from at least one of said light sources with a broad angular dispersion so that the light incident on the sample approaches a diffuse planar source of light.

14. Apparatus for use in measuring molecular constituents of a sample of whole blood comprising:

a housing having an optically transmissive chamber for receiving a sample of whole blood;

first and second light sources respectively having first and second narrow bands of wavelengths, said first and second light sources being oriented to illuminate a sample in the chamber when the light sources are transmitting light;

a sensor adapted to detect the first and second narrow band of wavelengths; and

a diffuser disposed between the sample and at least one of the light sources, said diffuser adapted to diffuse the light from at least one of said light sources incident on the sample, wherein said diffuser is further adapted to diffuse the light from said at least one light source with a broad angular dispersion so that the light incident on the sample approaches a diffuse planar source of light,

the first and second narrow bands of wavelengths being selected for the determination of hemoglobin concentration and/or hemoglobin oxygen saturation in whole blood,

a heater assembly for maintaining the blood in the sample chamber at a desired temperature.

15. Apparatus for use in measuring molecular constituents of a sample of whole blood comprising:

a housing having an optically transmissive chamber for receiving a sample of whole blood;

first and second light sources respectively having first and second narrow bands of wavelengths, said first and second light sources being oriented to illuminate a sample in the chamber when the light sources are transmitting light;

a sensor adapted to detect the first and second narrow band of wavelengths; and

a diffuser disposed between the sample and at least one of the light sources, said diffuser adapted to diffuse the light from at least one of said light sources incident on the sample, wherein said diffuser is further adapted to diffuse the light from said at least one light source with a broad angular dispersion so that the light incident on the sample approaches a diffuse planar source of light,

the first and second narrow bands of wavelengths are selected for the determination of one or more of the molecular constituents selected from the group consisting of oxyselected hemoglobin, dioxygenated hemoglobin, carboxyhemoglobin, methemoglobin, or hemiglobincyanide,

a heater assembly adapted to maintain the sample at a desired temperature.

16. An apparatus for use in providing in-vivo, real time measurement of selected blood characteristics, comprising:

a housing containing at least one optically transmissive blood chamber for receiving a sample of blood;

at least two light sources, each providing illumination within a narrow band of wavelengths, each of said light sources being oriented to illuminate first and second sensor assemblies for detecting pH and pCO2 of a blood sample in said blood chamber when the light sources are transmitting light,

the housing including first and second optically transmissive blood chambers for receiving a sample of blood;

the first light source being oriented to illuminate the first sensor for detecting pH of a blood sample in the first blood chamber;

the second light source being oriented to illuminate the second sensor for detecting pCO2

of a blood sample in the second blood chamber.

17. The apparatus of claim 16 wherein the first and second sensors are photodiodes for sensing the pH and pCO2 of the blood sample found within the first and second blood chambers.

18. An apparatus for use in providing in-vivo, real time measurement of selected blood characteristics, comprising:

a housing containing at least one optically transmissive blood chamber for receiving a sample of blood;

at least two light sources, each providing illumination within a narrow band of wavelengths, each of said light sources being oriented to illuminate first and second sensor assemblies for detecting pH and pCO2 of a blood sample in said blood chamber when the light sources are transmitting light,

means for maintaining the blood in the blood chambers at a desired temperature.

19. The apparatus of claim 18 wherein the first and second sensor assemblies for detecting the pH and pCO2 of the blood sample include first and second light sensing elements and first and second reflective assemblies of pH and pCO2, respectively, sensitive dye layers.

20. An apparatus for use in providing in-vivo, real time measurement of selected blood characteristics, comprising:

a housing containing at least one optically transmissive blood chamber for receiving a sample of blood;

at least two light sources, each providing illumination within a narrow band of wavelengths, each of said light sources being oriented to illuminate first and second sensor assemblies for detecting pH and pCO2 of a blood sample in said blood chamber when the light sources are transmitting light,

the first and second sensor assemblies for detecting the pH and pCO2 of the blood sample include first and second light sensing elements and first and second reflective assemblies of pH and pCO2, respectively, sensitive dye layers,

the first and second reflective elements of the first and second sensor assemblies being oriented with each light source and with the first and second light sensing elements to be illuminated by each light source through the blood sample and to illuminate the respective first and second light sensing elements;

the housing including an optical diffuser at the intersection of the light paths between the light sources, the reflective elements and the light sensing elements to provide for equal illumination of the light sensing elements; and

the light sources being sequentially stroked to provide illumination at each narrow band of wavelengths on the first and second sensor assemblies sensor at different times.

21. The apparatus of claim 20 wherein the pH and pCO2 sensitive indicators comprise assemblies of pH and pCO2, respectively, sensitive hydrogel layers, reflective layers, opaque layers, and appropriate blood contact layers.

22. The apparatus of claim 21 wherein

the first and second reflective elements of the first and second sensor assemblies are oriented with each light source and with the first and second light sensing elements to be illuminated by each light source through the blood sample and to illuminate the respective first and second light sensing elements;

the housing includes an optical diffuser at the intersection of the light paths between the light sources, the reflective elements and the light sensing elements to provide for equal illumination of the light sensing elements.

23. An apparatus for use in providing in-vivo, real time measurement of selected blood characteristics, comprising:

a housing containing at least one optically transmissive blood chamber for receiving a sample of blood;

at least two light sources, each providing illumination within a narrow band of wavelengths, each of said light sources being oriented to illuminate first and second sensor assemblies for detecting pH and pCO2 of a blood sample in said blood chamber when the light sources are transmitting light,

the housing including an additional optically transmissive blood chamber for receiving a sample of blood;

third and fourth light sources respectively having third and fourth narrow bands of wavelengths, said third and fourth light sources being oriented to illuminate a blood sample in the additional blood chamber when the third and fourth light sources are transmitting light;

a sensor adapted to detect the third and fourth narrow bands of wavelengths; and

a diffuser disposed between the sample and the third and fourth light sources, said diffuser adapted to diffuse the light from the third and fourth light sources incident on the sample.

24. The apparatus of claim 23 wherein the third and fourth narrow band wavelengths are selected for the determination of one or more of the molecular constituents selected from the group consisting of oxyselected hemoglobin, deoxygenated hemoglobin, carboxyhemoglobin, methemoglobin, or hemoglobincyanide.

25. The apparatus of claim 23 wherein the first and second sensors comprise photodiodes.

26. The apparatus of claim 23 wherein the third and fourth sensors comprise transmission intensity detectors.

27. The apparatus of claim 26 wherein the detectors are large area photodiodes.

28. The apparatus of claim 23 wherein the third and fourth narrow bands of wavelengths are selected for the determination of hemoglobin concentration and/or hemoglobin oxygen saturation in whole blood.

29. The apparatus of claim 23 wherein said diffuser is further adapted to diffuse the light from said third and fourth light sources illuminating the sample in the additional blood chamber with a broad angular dispersion so that the light incident on the sample in said additional blood chamber approaches a diffuse planar source of light.

30. The apparatus of claim 23 wherein the diffuser further comprises an optically transmissive material containing a dispersion of non-absorption light-scattering particles.

31. The apparatus of claim 23 wherein the apparatus includes means for maintaining the blood in the blood chambers at a desired temperature.

32. A method for determining the pH and/or pCO2 of a sample of blood comprising:

drawing a sample of blood into a housing having at least one optically transmissive chamber for receiving the sample;

contacting the sample with pH and pCO2 sensitive reflective indicators;

illuminating the indicators with light from at least two light sources each having a narrow band of wavelengths;

determining the reference intensity of the light from each light source incident on the indicators;

reflecting each narrow band of wavelengths from each indicator to at least one light sensor;

sensing the reflected light with the light sensor; and

determining the pH and/or pCO2 of the sample based on the relative amounts of light reflected by pH and pCO2 reflective indicators and the reference intensity.

33. The method of claim 32 wherein the illuminating step further comprises:

sequentially stroking the light sources at different times to illuminate the reflective indicators and the light sensor with each narrow band of wavelengths at a different time.

34. The method of claim 32 further comprising the steps of:

drawing the blood sample into at least one additional optically transmissive chamber of the housing;

illuminating the sample from at least two additional light sources with light having narrow bands of wavelengths appropriate for the determination of hemoglobin concentration and/or hemoglobin oxygen saturation in the blood sample in the additional chamber;

determining the reference intensity of the light from the additional light sources incident on the sample in the additional chamber;

diffusing the light from the additional light sources incident on the sample in the additional chamber;

detecting the diffused light from the additional light sources transmitted through the sample in the additional chamber; and

determining the hemoglobin concentration and/or hemoglobin oxygen saturation of the sample based on the relative amounts of light from the additional light sources absorbed by the sample in the additional chamber.

35. The method of claim 34 wherein the illuminating and determining steps further comprise:

illuminating the sample in the additional chamber from the additional light sources with light having narrow bands of wavelengths appropriate for the determination of one or more of the molecular constituents selected from the group consisting of oxyselected hemoglobin, deoxygenated hemoglobin, carboxyhemoglobin, methemoglobin, or hemoglobincyanide; and

determining one or more of the molecular constituents of the blood sample based on the relative amounts of light from the additional light sources absorbed by the sample in the additional chamber, the molecular constituents selected from the group consisting of oxyselected hemoglobin, deoxygenated hemoglobin, carboxyhemoglobin, methemoglobin, or hemoglobincyanide.

36. The method of claim 34 wherein said diffusing step further comprises:

diffusing the light from each light source illuminating the sample with a broad angular dispersion so that the light incident on the sample approaches a diffuse planar source of light.

37. The method of claim 34 wherein said diffusing step further comprises:

passing the light through an optically transmissive material containing a dispersion of non-absorptive light-scattering particles.

38. The method of claim 34 wherein said diffusing step further comprises:

passing the light through an optically transmissive material containing a dispersion of non-absorptive light-scattering particles; and

diffusing the light from each light source illuminating the sample with a broad angular dispersion so that the light incident on the sample approaches a diffuse planar source of light.