System and method for monitoring of end organ oxygenation by measurement of in vivo cellular energy status

• US 20070038126A1
• Filed: 06/23/2006
• Published: 02/15/2007
• Est. Priority Date: 06/23/2005
• Status: Abandoned Application

• Current Assignee: EPOC, Inc.
• Original Assignee: EPOC, Inc.
• Inventors: Roe, Jeffrey, Aravanis, Alexander, Rosenthal, Myer, Pyle, Jason
• Application Number:
  US11/473,976
• Publication Number:
  US 20070038126A1
• Time in Patent Office: Days
• US Class Current: 600/476
• CPC Class Codes: A61B 5/0059 using light, e.g. diagnosis by transillumination, diascopy, fluorescence A61B5/0093, A61B5/1455, A61B5/02416 and A61B5/0261 take precedence
• CPC Class Codes: A61B 5/0068 Confocal scanning
• CPC Class Codes: A61B 5/0071 by measuring fluorescence emission
• CPC Class Codes: A61B 5/0084 for introduction into the body, e.g. by catheters A61B5/1459 takes precedence
• CPC Class Codes: A61B 5/14556 by fluorescence A61B5/14555 takes precedence
• CPC Class Codes: A61B 5/412 Detecting or monitoring sepsis
• CPC Class Codes: A61B 5/413 Monitoring transplanted tissue or organ, e.g. for possible rejection reactions after a transplant

Abstract

A method is provided of measuring in vivo of an endogenous fluorophore in a tissue site. A known excitation wavelength of the endogenous flurophore is selected within a range of wavelengths at which the endogenous flurophore undergoes fluorescence. The tissue site is irradiated with irradiated light having at least the selected excitation wavelength within the range of wavelengths. A fluorescence emission of the tissue site resulting from the irradiation thereof is detected. A relative or absolute concentration of the endogenous fluorophore is determined by multiplying it by a calibration factor that depends one at least one of, a known excitation and emission property of the endogenous fluorophore, an intensity of the irradiated light, optical properties of an excitation probe, and specific properties of the tissue. The relative or absolute concentration of the endogenous fluorphore is used to estimate at least one of a, in vivo cellular energy production status or state of end-organ tissue oxygenation.

Claims

1. A method of measuring in vivo of an endogenous fluorophore in a tissue site, comprising:

selecting a known excitation wavelength of the endogenous flurophore within a range of wavelengths at which the endogenous flurophore undergoes fluorescence;

irradiating the tissue site with irradiated light having at least the selected excitation wavelength within the range of wavelengths;

detecting a fluorescence emission of the tissue site resulting from the irradiation thereof;

determining a relative or absolute concentration of the endogenous fluorophore by multiplying it by a calibration factor that depends one at least one of, a known excitation and emission property of the endogenous fluorophore, an intensity of the irradiated light, optical properties of an excitation probe, and specific properties of the tissue;

using the relative or absolute concentration of the endogenous fluorphore to estimate at least one of a, in vivo cellular energy production status or state of end-organ tissue oxygenation.

2. The method of claim 1, wherein the determining is in response to at least one of, known relations between the concentration of the fluorophore and the in vivo cellular energy production status, state of end-organ tissue oxygenation, or upon an experimentally derived calibration.

3. The method of claim 2, further comprising:

detecting reflected and scattered components of the excitation wavelengths incident upon the tissue site.

4. The method of claim 3, wherein absolute or relative concentrations are measured of at least one of the molecules selected from the group elastin, collagen, flavin adenine dinucleotide (FADH2 and FAD2+, nicotinamide adenine dinucleotide (NAD(P)H and NAD(P)+), phenylalanine, pyridoxal 5′

phosphate, tryptophan, and tyrosine.

5. The method of claim 4, wherein fluorescence detections are taken at multiple excitation and multiple emission wavelengths.

6. The method of claim 5, further comprising:

using the fluorescence detections to determine an absolute or relative concentration of one or more chemical species.

7. The method of claim 6, further comprising:

taking ratios of the fluorescence detections at different excitation and emission wavelength pairs to cancel out one or more of the following;

background signals that do not vary with wavelength, fluorescent signals from endogenous fluorphores that do not vary with changes in in vivo cellular energy production status and state of end-organ tissue oxygenation, reflected or scattered excitation light, instrumental variation in the optics or other components, and variation in probe placement.

8. The method of claim 7, wherein the fluorescence detections are taken of at least one of selected excitation and emission wavelengths where selected species have near identical absorption or emission spectra to estimate an absolute or relative concentration of the sum of the selected species.

9. The method of claim 8, further comprising:

using fluorescence detections made at multiple spatial locations of the tissue site to determine gradients of at least one of, chemical species, in vivo cellular energy production status, and state of end-organ tissue oxygenation.

10. The method of claim 9, wherein the fluorescence detections are used to determine quantities at the tissue site of at least one of, a percent of reduced NAD(P), a percent of oxidized NAD(P), a NAD(P)+/NAD(P)H ratio, a percent of reduced FAD, a percent of oxidized FAD, a FAD+/FADH2 ratio, a percent of ischemia, a percent of perfusion, a percent of a perfusion deficit, in vivo cellular energy production status, and state of end-organ tissue oxygenation.

11. The method of claim 10, further comprising:

using a control module to allow a user to change output displays or view data in a graphical form.

12. The method of claim 11, further comprising:

using the fluorescence detection to determine at the tissue site an indication of at least one of, end organ perfusion monitoring in an acute care situation, a direct Intra-operative fluorescence detection of tissue oxygenation in transplanted organs, a direct Intra-operative fluorescence detection of tissue oxygenation in surgery, and an evaluation of peripheral vascular disease.

13. The method of claim 12, wherein the tissue site is irradiated with a probe.

14. The method of claim 13, wherein the probe is an implantable apparatus.

15. The method of claim 14, wherein the implantable apparatus is configured to have at least one of, wireless control, data-retrieval, and battery recharging.

16. The method of claim 15, further comprising:

swallowing the probe to irradiate the tissue site.

17. The method of claim 16, wherein the probe provides intermittent or continuous fluorescence detections while passing through the GI tract.

18. The method of claim 17, further comprising:

accessing fluorescence detection data with the probe in real-time with wireless telemetry.

19. The method of claim 18, wherein the probe is recovered from the GI tract with subsequent off-line analysis of fluorescence detection data.

20. The method of claim 19, wherein the tissue site is irradiated with the use of at least one of a, GRIN lens, scanning laser for photon confocal imaging, and a scanning laser for two-photon imaging.

21. The method of claim 20, wherein the fluorescence detections are transvascular, i.e. through a blood vessel wall.

22. The method of claim 21, further comprising:

using a scanning laser to make 2D and 3D spatial fluorescence detections at surfaces parallel and perpendicular to a tissue site surface.

23. The method of claim 22, further comprising:

using a device that provides 2D and 3D spatial fluorescence detections, such as an imaging endoscope, scanning laser, fiber bundle,.GRIN lens, confocal imaging system, and 2 -photon imaging system.

24. The method of claim 23, further comprising:

using a light source selected from the group of LEDS, laser diodes, lasers, metal halide lamps, and gas arc lamps.

25. The method of claim 24, further comprising:

using a detector selected from at least one of a, photodiode, avalanche photodiode, CCD, and PMT.

26. The method of claim 25, further comprising:

using an endoscope with a detector and a light source.

27. The method of claim 26, further comprising:

using pulse oximetry to make fluorescence detections of tissue oxygenation verses blood oxygenation at the tissue site.

28. The method of claim 27, further comprising:

using a mechanical device to anchor the probe to tissue.

29. The method of claim 28, further comprising:

using at least one of, vacuum, hooks, inflatable balloons, chemical adhesives, and expandable cages to anchor the probe.

30. The method of claim 29, wherein oxygenation of in vivo tissue is monitored by measurement of biochemical processes intrinsic to cellular respiration.

31. The method of claim 30, wherein multivariant analysis, using excitation light at 200 nm-420 nm and measuring emission light at 300 nm-800 nm, is used to determine optimal optical wavelengths for detection of the selected one of more fluorphores.

32. A method of measuring in vivo of endogenous fluorophores in a tissue site, comprising:

Irradiating the tissue site at multiple irradiation wavelengths with excitation wavelengths known to excite one or more selected endogenous fluorophores;

receiving a measured emission wavelength response of an emitted light intensity for one or more of the excitation wavelengths;

forming an equation for each measured emission wavelength where the measured emission wavelength is equal to a sum of the responses from the selected endogenous fluorophores; and

forming a system of equations where there is an equation for each combination of an irradiation wavelength and measured emission wavelength.

33. The method of claim 32, further comprising:

solving the system of equations for absolute or relative concentrations of each of the selected endogenous fluorophores. determining a concentration of the selected endogenous fluorophores.

34. The method of claim 33, further comprising:

determining at the tissue site at least one of, in vivo cellular energy production status, and state of end-organ tissue oxygenation.

35. The method of claim 34, wherein the determining at the tissue site at least one of, in vivo cellular energy production status, and state of end-organ tissue oxygenation is based on known relations between the concentrations of the selected endogenous fluorophores and in vivo cellular energy production status and state of end-organ tissue oxygenation or an experimentally derived calibration.

36. The method of claim 35, further comprising:

correcting for at least one of, background endogenous flurophores, instrumental variation, and positioning of a radiation delivery device at the tissue site.

37. The method of claim 36, further comprising:

displaying a result.

38. A method of monitoring energy production status of in vivo tissue, comprising:

measuring emission of first and second groups of endogenous flurophores, the first group having quantity or emitting characteristics that vary with cellular respiration of oxygen, and the second group having quantity or emitting characteristics that vary with energy production status of mammalian cells; and

determining a concentration of one or more of the endogenous fluorophore;

determining a relative or absolute concentration of the endogenous fluorophore by multiplying it by a calibration factor that depends one at least one of, a known excitation and emission property of the endogenous fluorophore, an intensity of the irradiated light, optical properties of an excitation probe, and specific properties of the tissue;

using the relative or absolute concentration of the endogenous fluorophore to estimate at least one of a, in vivo cellular energy production status or state of end-organ tissue oxygenation.

39. The method of claim 38, further comprising:

measuring an electromagnetic signal from intrinsic emission molecules whose quantity or emitting characteristics do not substantially vary in response to a physiological state of energy production status or oxygenation.

40. The method of claim 39, wherein a signal of target molecules and background molecules is separated from endogenous fluorophores whose quantity or emitting characteristics vary significantly in response to physiological variables other than cellular oxygenation or energy production status.

41. The method of claim 40, wherein electromagnetic signals from endogenous fluorophores are separated by at least one of, passive bandwidth filtering, active and or adaptive physical or electronic filtering, and time resolved fluorescent detection to accomplish monitoring of in vivo energy production status or cellular oxygenation.

42. The method of claim 41, wherein a monitoring signal includes emissions of one or more endogenous fluorophores that vary in response to the energy production status or cellular oxygenation of in vivo tissue in combination with the emissions of one or more intrinsic emission molecules whose signal does not vary in response to the energy production status or cellular oxygenation of an in vivo tissue.

43. The method of claim 42, wherein a single band or multiple bands of an electromagnetic signal is isolated by frequency or temporal response monitored to measure in vivo energy production status or cellular respiration.

44. The method of claim 43, further comprising:

determining a ratio from a signal of an endogenous fluorophore or bands of signals from multiple endogenous fluorophores to measure energy production status or cellular respiration of an in vivo tissue.

45. The method of claim 44, wherein energy production status or cellular respiration of an in vivo tissue is measured in at least one of, a single measurement, measured at any frequency, and measured continuously.

46. A system for measuring in vivo at least one of endogenous fluorophores s in a tissue site, comprising:

a light source that produces an excitation wavelength of the endogenous flurophore within a range of wavelengths at which the endogenous flurophore undergoes fluorescence;

a detector for detecting a fluorescence emission of the tissue site resulting from the irradiation thereof; and

a processor configured to analyze the detected emission to determine the presence of the endogenous flurophore in the tissue site.

47. The system of claim 46, wherein the detector detects reflected and scattered components of the excitation wavelengths incident upon the tissue site.

48. The system of claim 47, wherein the system measures absolute or relative concentrations of at least one of at least one molecule selected from the group elastin, collagen, flavin adenine dinucleotide (FADH2 and FAD2+, nicotinamide adenine dinucleotide (NAD(P)H and NAD(P)+), phenylalanine, pyridoxal 5′

phosphate, tryptophan, and tyrosine.

49. The system of claim 48, wherein the system takes measurements at multiple excitation and multiple emission wavelengths are taken.

50. The system of claim 49, wherein the system uses the measurements to determine an absolute or relative concentration of 1 or more chemical species.

51. The system of claim 50, wherein the processor takes ratios of the fluorescence measurements at different excitation and emission wavelength pairs to cancel out one or more of the following:

background signals that do not vary with wavelength, fluorescent signals from endogenous fluorphores that do not vary with changes in in vivo cellular energy production status and state of end-organ tissue oxygenation, reflected or scattered excitation light, instrumental variation in the optics or other components, and variation in probe placement.

52. The system of claim 51, wherein the processor uses measurements taken of at least one of selected excitation and emission wavelengths where selected species have near identical absorption or emission spectra to estimate an absolute or relative concentration of the sum of the selected species.

53. The system of claim 52, wherein the processor uses measurements made at multiple spatial locations of the tissue site to determine gradients of at least one of, chemical species, in vivo cellular energy production status, and state of end-organ tissue oxygenation.

54. The system of claim 53, wherein the measurements are used to determine quantities at the tissue site of at least one of, a percent of reduced NAD(P), a percent of oxidized NAD(P), a NAD(P)+/NAD(P)H ratio, a percent of reduced FAD, a percent of oxidized FAD, a FAD+/FADH2 ratio, a percent of ischemia, a percent of perfusion, a percent of a perfusion deficit, a tissue state that is aerobic or anerobic.

55. The system of claim 54, further comprising:

a control module to allow a user to change output displays or view data in a graphical form.

56. The system of claim 55, wherein the tissue site is irradiated with a probe.

57. The system of claim 56, wherein the probe is an implantable apparatus.

58. The system of claim 57, wherein the implantable apparatus is configured to have at least one of, wireless control, data-retrieval, and battery recharging.

59. The system of claim 58, wherein the probe provides intermittent or continuous measurements while passing through the GI tract.

60. The system of claim 59, wherein the probe accesses measurement data with the probe in real-time with wireless telemetry.

61. The system of claim 60, wherein the probe is recovered from the GI tract with subsequent off-line analysis of measurement data.

62. The system of claim 61, further comprising at least one of a GRIN lens, dichroic mirror, excitation filter, emission filter, and a light conduit.

63. The system of claim 62, wherein the light source is selected from an LED, laser diode, laser, metal halide lamp, gas arc lamp, scanning laser for confocal imaging, and a scanning laser for 2-photon imaging.

64. The system of claim 63, wherein the measurements are through a blood vessel wall.

65. The system of claim 64, wherein the light source is a scanning laser and 2D and 3D spatial measurements are at surfaces parallel and perpendicular to a tissue site surface.

66. The system of claim 65, further comprising:

a device to provide 2D and 3D spatial measurements such as an imaging endoscope, scanning laser, fiber bundle, GRIN lens, confocal imaging system, and 2-photon imaging system.

67. The system of claim 66, wherein the light source is selected from the group of LEDS, laser diodes, lasers, and an arc lamp.

68. The system of claim 67, wherein the detector is selected from at least one of a, photodiode, avalanche photodiode, CCD, and PMT.

69. The system of claim 68, further comprising:

an endoscope used with the detector and the light source.

70. The system of claim 69, further comprising:

a pulse oximetry system to make measurements of tissue oxygenation verses blood oxygenation at the tissue site.

71. The system of claim 70, further comprising:

a mechanical device to anchor the probe to tissue.

72. The system of claim 71, further comprising:

at least one of a vacuum source, hooks, inflatable balloons and expandable cages to anchor the probe.

73. The system of claim 72, further comprising:

an delivery device coupled to the probe.

74. The system of claim 73, wherein the delivery device is a catheter configured to be placed through at least one of the, mouth, nasal cavity, rectum and urethrea, intravascularly, and into a body cavity by penetration of the skin surface.

75. The system of claim 74, further comprising:

a device that passes excitation, light from the light source outside the body through a conduit to a location inside the body to be used for the excitation of the endogenous fluorophores.

76. The system of claim 75, wherein the device that passes excitation light is selected from at least one of, a fiber optic element and a device that contains one or more liquid light guide elements.

77. The system of claim 76, further comprising:

a device that collects light emitted by the endogenous fluorophores and acts as a conduit for that light to be measured.

78. The system of claim 77, wherein the device that collects light is selected from at least one of, a fiber optic element that transmit the light from an in vivo region to the detector and a liquid light guide elements to transmit the light from the in vivo region to a detection apparatus outside the body for this purpose.

79. The system of claim 78, further comprising:

a device that acts as a conduit to pass excitation light from the light source outside a body and collects light emitted by the endogenous fluorophores.

80. The system of claim 79, wherein the device that acts as a conduit is selected from at least one of, a fiber optic element and a liquid light guide element.

81. The system of claim 80, wherein the light source is insertable into a body of the tissue site.

82. The system of claim 81, wherein the detector is insertable into a body of the tissue site.

83. The system of claim 82, wherein the light source and the detector are combined in a single device that is insertable into a body of the tissue site.

84. The system of claim 83, further comprising:

a disposable light delivery deliver coupled to the light source and insertable into a body of the tissue site.

85. The system of claim 84, further comprising:

a device that is segmented into disposable and reusable components for the purpose of exciting or collecting light emission of the endogenous fluorophores.

86. The system of claim 85, further comprising:

a device that excites or collects emission of endogenous fluorophores with a separate lumen suitable for the passing or removing fluids.

87. The system of claim 86, wherein the device that excites or collects emission is inserted through at least one of a, nose, mouth, urethra and vasculature.

88. The system of claim 87, further comprising:

a device that has at least one of a, unidirectional, multidirectional and omni-directional optical tip inserted into a body of the tissue site.

89. The system of claim 88, further comprising:

a device external from a body of the tissue site configured to be coupled to a probe inserted into the body.

90. The system of claim 89, wherein the light source includes optical and electronic elements.

91. The system of claim 90, wherein the detector includes optical and electronic elements.

92. The system of claim 91, further comprising:

a device external from a body of the insertable device that provides processing, filtering, and reporting of signals acquired from emission of the endogenous fluorophores.

93. The system of claim 92, wherein the light source is a scanning laser selected from a, confocal scanning laser and a two photon scanning laser.

94. The system of claim 93, wherein an electrically-acutated movablemicro-mirror is used to provide scanning.