Apparatuses and methods for non-invasively monitoring blood parameters

• US 7,341,560 B2
• Filed: 10/05/2004
• Issued: 03/11/2008
• Est. Priority Date: 10/05/2004
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Rader Fishman & Grauer (Fishman Stewart PLLC)
• Inventors: Henderson, Leslie G., Bailey, Theodore M.
• Primary Examiner(s): WINAKUR, ERIC FRANK
• Application Number:
  US10/958,458
• Publication Number:
  US 20060074283A1
• Time in Patent Office: 1,253 Days
• Field of Search: 600/323, 600/324, 600/499, 600/483, 600/485, 600/502, 600/310, 600/322, 600/340
• US Class Current: 600/500
• CPC Class Codes: A61B 2560/0412 Low-profile patch shaped housings
• 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 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/02125 of pulse wave propagation time
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• 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 5/6814 Head
• CPC Class Codes: A61B 5/6824 Arm or wrist
• CPC Class Codes: A61B 5/6826 Finger
• CPC Class Codes: A61B 5/6838 Clamps or clips

Abstract

An apparatus for monitoring vital sign parameters in a biological entity is disclosed. In an embodiment, the apparatus includes at least one light source for transmitting light through the biological entity and at least one photodetector for receiving light transmitted through the biological entity. At least one light source and at least one photodetector are configured to be positioned proximate the biological entity in a manner that does not significantly impede blood flow through the biological entity. A signal is generated in response to the transmittance or reflectance of light through the biological entity. The signal corresponds to at least one characteristic of the generally unimpeded blood flow through the biological entity. The apparatus also includes a control system configured to analyze the signal to determine vital sign parameters in the biological entity. A method for monitoring vital sign parameters in a biological entity is also provided.

Claims

1. A method for monitoring vital sign parameters in a biological entity comprising the steps of:

adhering at least one sensor assembly proximate the biological entity in a manner that does not significantly impede blood flow through the biological entity;

generating a signal by the sensor assembly corresponding to at least one characteristic of blood flow through the biological entity; and

analyzing the signal to determine vital sign parameters in the biological entity, wherein analyzing the signal includes calculating the upward slope of the generated signal to determine Myocardial Contractility.

2. The method according to claim 1, further comprising the step of sampling the generated signal at periodic times to develop a reference envelope having a lower limit band and an upper limit band.

3. The method according to claim 2, further comprising the step of setting the sampling period.

4. The method according to claim 3, wherein the sampling period is determined by an operator.

5. The method according to claim 3, wherein the sampling period is determined by the control system and is based on historical data.

6. The method according to claim 2, further comprising the steps of setting the lower band limit and the upper band limit.

7. The method according to claim 6, wherein the sampling period is determined by an operator.

8. The method according to claim 6, wherein the sampling period is determined by the control system and is based on historical data.

9. The method according to claim 2, further comprising the step of employing the reference envelope to monitor subsequent generated signals.

10. The method according to claim 9, further comprising the step of analyzing the generated signal to determine when the generated signal crosses the upper band limit.

11. The method according to claim 9, further comprising the step of analyzing the generated signal to determine when the generated signal crosses the lower band limit.

12. The method according to claim 2, further comprising the step of creating a number of databases containing envelopes that correspond to the vital sign parameters of one or more of the following of gender, age, height, weight, and race.

13. The method according to claim 12, further comprising the step of comparing the generated signal with the envelopes contained in the database.

14. The method of claim 2, further comprising the step of creating a database containing envelopes that correspond to the vital sign parameters of a single person.

15. The method of claim 14, further comprising the step of comparing the generated signal with the envelopes contained in the database.

16. The method according to claim 2, further comprising the step of comparing the generated signal with the envelopes to determine the performance of the cardiovascular and pulmonary systems in the biological entity.

17. The method according to claim 1, further comprising the step of generating a second signal from the sensor assembly corresponding to at least one characteristic of blood flow through the biological entity.

18. The method according to claim 17, further comprising the step of analyzing the second generated signal to determine vital sign parameters in the biological entity.

19. The method according to claim 17, wherein the second signal is generated from a different location of the biological entity than the signal.

20. The method according to claim 19, further comprising the step of comparing the generated signal with the second generated signal to identify changes in vital sign parameters in the biological entity.

21. The method according to claim 17, further comprising the steps of determining respiration rate in the biological entity by detecting rhythmic changes in blood oxygen saturation corresponding to respiration rate.

22. The method according to claim 1, further comprising the step of determining blood oxygen saturation from the generated signal in the biological entity.

23. The method according to claim 1, further comprising the step of creating a Myocardial Contractility Index based on multiple Myocardial Contractility measurements.

24. The method according to claim 1, wherein analyzing the signal includes calculating the area under a first portion of the curve of the generated signal to determine Tissue Perfusion.

25. The method according to claim 24, further comprising the step of creating a Tissue Perfusion Index based on multiple Tissue Perfusion measurements.

26. The method according to claim 1, wherein analyzing the signal includes calculating the area under a second portion of the curve of the generated signal to determine Vascular Elasticity.

27. The method according to claim 26, further comprising the step of creating a Vascular Elasticity Index based on multiple Vascular Elasticity measurements.

28. The method according to claim 1, further comprising the step of comparing the generated signal to a second signal generated from the electrical activity of the heart to monitor for electromechanical disassociation.

29. The method according to claim 28, wherein the second signal is an electrocardiogram (EKG) signal.

30. A method for monitoring blood parameters in a biological entity, comprising:

adhering at least one sensor assembly proximate the biological entity in a manner that does not significantly impede blood flow though the biological entity;

progressively obstructing blood flow through the biological entity;

while progressively obstructing blood flow through the biological entity, generating a signal from the sensor assembly corresponding to at least one characteristic of the blood flow through the biological entity;

analyzing the signal to determine blood pressure in the biological entity; and

sampling the generated signal at periodic times to develop a reference envelope having a lower limit band and an upper limit band, wherein analyzing a stead state portion of the signal includes calculating the upward slope of the generated steady state portion of the signal to determine Myocardial Contractility.

31. The method according to claim 30, wherein analyzing the signal further includes identifying oscillations in the signal that correspond to one of mean arterial blood pressure, diastolic blood pressure, and systolic blood pressure.

32. The method of claim 31, wherein analyzing the signal further includes relating an amplitude of the oscillations in the signal corresponding to diastolic blood pressure and systolic blood pressure to an amplitude of the oscillation in the signal corresponding to mean arterial blood pressure.

33. The method according to claim 32, wherein analyzing the signal further includes relating the amplitude of the oscillation corresponding to diastolic blood pressure, identified as A_d, to the amplitude of the oscillation corresponding to mean arterial blood pressure, identified as A_m, such that A_d/A_m=X, where X is an empirically determined constant.

34. The method according to claim 32, wherein analyzing the signal further includes relating the amplitude of the oscillation corresponding to diastolic blood pressure, identified as A_s, to the amplitude of the oscillation corresponding to mean arterial blood pressure, identified as A_m, such that A_s/A_m=Y, where Y is an empirically determined constant.

35. The method according to claim 30, wherein progressively obstructing blood flow through the biological entity includes:

applying pressure to the biological entity at a first rate;

maintaining a predetermined pressure sufficient to substantially obstruct the flow of blood through the biological entity for a predetermined period of time; and

relieving the pressure on the biological entity.

36. The method according to claim 35, wherein relieving the pressure on the biological entity is further defined by relieving the pressure at a second rate that is substantially equal to the first rate.

37. The method according to claim 35, wherein analyzing the signal includes:

determining a first mean arterial blood pressure while the pressure is being applied to the biological entity at a first rate; and

determining a second mean arterial blood pressure while the pressure is being relieved.

38. The method according to claim 37, wherein analyzing the signal further includes averaging the first mean arterial blood pressure and the second mean arterial blood pressure to determine a final mean arterial blood pressure.

39. The method according to claim 30, further including the step of determining a heart rate in the biological entity prior to progressively obstructing blood flow through the biological entity.

40. The method according to claim 30, further comprising the step of setting the sampling period.

41. The method according to claim 40, wherein the sampling period is determined by an operator.

42. The method according to claim 40, wherein the sampling period is determined by the control system and is based on historical data.

43. The method according to claim 30, further comprising the steps of setting the lower band limit and the upper band limit.

44. The method according to claim 43, wherein the sampling period is determined by an operator.

45. The method according to claim 43, wherein the sampling period is determined by the control system and is based on historical data.

46. The method according to claim 30, wherein analyzing the signal to determine blood pressure in the biological entity includes comparing the generated signal to a reference envelope.

47. The method according to claim 46, further comprising the step of analyzing the generated signal to determine when the generated signal crosses the upper band limit.

48. The method according to claim 46, further comprises the step of analyzing the generated signal to determine when the generated signal crosses the lower band limit.

49. The method according to claim 46, wherein analyzing the signal to determine blood pressure in the biological entity includes continuously or near-continuously analyzing the signal to provide a continuous or near-continuous determination of blood pressure in the biological entity.

50. The method according to claim 30, further comprising the step of analyzing the reference envelope to identify a peak amplitude that is equal to mean arterial pressure.

51. The method according to claim 30, further comprising the step of creating a Myocardial Contractility Index based on multiple Myocardial Contractility measurements.

52. The method according to claim 30, wherein analyzing the steady state portion of the signal includes calculating the area under a first portion of the curve of the generated steady state portion of the signal to determine Tissue Perfusion.

53. The method according to claim 52, further comprising the step of creating a Tissue Perfusion Index based on multiple Tissue Perfusion measurements.

54. The method according to claim 52, wherein analyzing the steady state portion of the signal includes calculating the area under a second portion of the curve of the generated steady state portion of the signal to determine Vascular Elasticity.

55. The method according to claim 54, further comprising the step of creating a Vascular Elasticity Index based on multiple Vascular Elasticity measurements.

56. The method according to claim 54, wherein the mean arterial blood pressure, Myocardial Contractility, Tissue Perfusion, and Vascular Elasticity are compared to provide a diagnostic picture of the pulmonary system.

57. A method for monitoring vital sign parameters in a biological entity comprising the steps of:

positioning at least one sensor assembly proximate the biological entity in a manner that does not significantly impede blood flow through the biological entity;

generating a signal by the sensor assembly corresponding to at least one characteristic of blood flow though the biological entity;

analyzing the signal to determine vital sign parameters in the biological entity;

sampling the generated signal at periodic times to develop a reference envelope having a lower limit band and an upper limit band;

employing the reference envelope to monitor subsequent generated signals; and

analyzing the generated signal to determine when the generated signal crosses the upper band limit.

58. The method according to claim 57, further comprises the step of analyzing the generated signal to determine when the generated signal crosses the lower band limit.

59. A method for monitoring vital sign parameters in a biological entity comprising the steps of:

positioning at least one sensor assembly proximate the biological entity in a manner that does not significantly impede blood flow through the biological entity;

generating a signal by the sensor assembly corresponding to at least one characteristic of blood flow through the biological entity;

analyzing the signal to determine vital sign parameters in the biological entity;

sampling the generated signal at periodic times to develop a reference envelope having a lower limit band and an upper limit band; and

creating a number of databases containing envelopes that correspond to the vital sign parameters of one or more of the following of gender, age, height, weight, and race.

60. The method according to claim 59, further comprising the step of comparing the generated signal with the envelopes contained in the database.

61. A method for monitoring vital sign parameters in a biological entity comprising the steps of:

positioning at least one sensor assembly proximate the biological entity in a manner that does not significantly impede blood flow through the biological entity;

generating a signal by the sensor assembly corresponding to at least one characteristic of blood flow through the biological entity;

analyzing the signal to determine vital sign parameters in the biological entity;

sampling the generated signal at periodic times to develop a reference envelope having a lower limit band and an upper limit band; and

creating a database containing envelopes that correspond to the vital sign parameters of a single person.

62. The method of claim 61, further comprising the step of comparing the generated signal with the envelopes contained in the database.

63. A method for monitoring vital sign parameters in a biological entity comprising the steps of:

positioning at least one sensor assembly proximate the biological entity in a manner that does not significantly impede blood flow through the biological entity;

generating a signal by the sensor assembly corresponding to at least one characteristic of blood flow through the biological entity;

analyzing the signal to determine vital sign parameters in the biological entity; and

wherein analyzing the signal includes calculating the upward slope of the generated signal to determine Myocardial Contractility.

64. The method according to claim 63, further comprising the step of creating a Myocardial Contractility Index based on multiple Myocardial Contractility measurements.

65. A method for monitoring vital sign parameters in a biological entity comprising the steps of:

positioning at least one sensor assembly proximate the biological entity in a manner that does not significantly impede blood flow through the biological entity;

generating a signal by the sensor assembly corresponding to at least one characteristic of blood flow through the biological entity;

analyzing the signal to determine vital sign parameters in the biological entity; and

wherein analyzing the signal includes calculating the area under a first portion of the curve of the generated signal to determine Tissue Perfusion.

66. The method according to claim 65, further comprising the step of creating a Tissue Perfusion Index based on multiple Tissue Perfusion measurements.

67. A method for monitoring vital sign parameters in a biological entity comprising the steps of:

positioning at least one sensor assembly proximate the biological entity in a manner that does not significantly impede blood flow through the biological entity;

generating a signal by the sensor assembly corresponding to at least one characteristic of blood flow through the biological entity;

analyzing the signal to determine vital sign parameters in the biological entity; and

wherein analyzing the signal includes calculating the area under a second portion of the curve of the generated signal to determine Vascular Elasticity.

68. The method according to claim 67, further comprising the step of creating a Vascular Elasticity Index based on multiple Vascular Elasticity measurements.

69. A method for monitoring vital sign parameters in a biological entity comprising the steps of:

positioning at least one sensor assembly proximate the biological entity in a manner that does not significantly impede blood flow through the biological entity;

generating a signal by the sensor assembly corresponding to at least one characteristic of blood flow through the biological entity;

analyzing the signal to determine vital sign parameters in the biological entity; and

comparing the generated signal to a second signal generated from the electrical activity of the heart to monitor for electromechanical disassociation.

70. The method according to claim 69, wherein the second signal is an electrocardiogram (EKG) signal.

71. A method for monitoring blood parameters in a biological entity, comprising:

positioning at least one sensor assembly proximate the biological entity in a manner that does not significantly impede blood flow through the biological entity;

progressively obstructing blood flow through the biological entity;

while progressively obstructing blood flow through the biological entity, generating a signal from the sensor assembly corresponding to at least one characteristic of the blood flow though the biological entity;

analyzing the signal to determine blood pressure in the biological entity;

sampling the generated signal at periodic times to develop a reference envelope having a lower limit band and an upper limit band;

wherein analyzing the signal to determine blood pressure in the biological entity includes comparing the generated signal to a reference envelope; and

analyzing the generated signal to determine when the generated signal crosses the upper band limit.

72. A method for monitoring blood parameters in a biological entity, comprising:

positioning at least one sensor assembly proximate the biological entity in a manner that does not significantly impede blood flow through the biological entity;

progressively obstructing blood flow through the biological entity;

while progressively obstructing blood flow though the biological entity, generating a signal from the sensor assembly corresponding to at least one characteristic of the blood flow through the biological entity;

analyzing the signal to determine blood pressure in the biological entity;

sampling the generated signal at periodic times to develop a reference envelope having a lower limit band and an upper limit band;

wherein analyzing the signal to determine blood pressure in the biological entity includes comparing the generated signal to a reference envelope; and

analyzing the generated signal to determine when the generated signal crosses the lower band limit.

73. A method for monitoring blood parameters in a biological entity, comprising:

positioning at least one sensor assembly proximate the biological entity in a manner that does not significantly impede blood flow through the biological entity;

progressively obstructing blood flow through the biological entity;

while progressively obstructing blood flow though the biological entity, generating a signal from the sensor assembly corresponding to at least one characteristic of the blood flow though the biological entity;

analyzing the signal to determine blood pressure in the biological entity;

sampling the generated signal at periodic times to develop a reference envelope having a lower limit band and an upper limit band; and

wherein analyzing a steady state portion of the signal includes calculating the upward slope of the generated steady state portion of the signal to determine Myocardial Contractility.

74. The method according to claim 73, further comprising the step of creating a Myocardial Contractility Index based on multiple Myocardial Contractility measurements.

75. The method according to claim 73, wherein analyzing the steady state portion of the signal includes calculating the area under a first portion of the curve of the generated steady state portion of the signal to determine Tissue Perfusion.

76. The method according to claim 75, further comprising the step of creating a Tissue Perfusion Index based on multiple Tissue Perfusion measurements.

77. The method according to claim 75, wherein analyzing the steady state portion of the signal includes calculating the area under a second portion of the curve of the generated steady state portion of the signal to determine Vascular Elasticity.

78. The method according to claim 77, further comprising the step of creating a Vascular Elasticity Index based on multiple Vascular Elasticity measurements.

79. The method according to claim 77, wherein the mean arterial blood pressure, Myocardial Contractility, Tissue Perfusion, and Vascular Elasticity are compared to provide a diagnostic picture of the pulmonary system.

80. A method for monitoring vital sign parameters in a biological entity comprising the steps of:

adhering at least one sensor assembly proximate the biological entity in a manner that does not significantly impede blood flow through the biological entity;

generating a signal by the sensor assembly corresponding to at least one characteristic of blood flow through the biological entity; and

analyzing the signal to determine vital sign parameters in the biological entity; and

comparing the generated signal to a second signal generated from the electrical activity of the heart to monitor for electromechanical disassociation.

81. The method according to claim 80, further comprising the step of sampling the generated signal at periodic times to develop a reference envelope having a lower limit band and an upper limit band.

82. The method according to claim 81, further comprising the step of setting the sampling period.

83. The method according to claim 82, wherein the sampling period is determined by an operator.

84. The method according to claim 82, wherein the sampling period is determined by the control system and is based on historical data.

85. The method according to claim 81, further comprising the steps of setting the lower band limit and the upper band limit.

86. The method according to claim 85, wherein the sampling period is determined by an operator.

87. The method according to claim 85, wherein the sampling period is determined by the control system and is based on historical data.

88. The method according to claim 81, further comprising the step of employing the reference envelope to monitor subsequent generated signals.

89. The method according to claim 88, further comprising the step of analyzing the generated signal to determine when the generated signal crosses the upper band limit.

90. The method according to claim 88, further comprising the step of analyzing the generated signal to determine when the generated signal crosses the lower band limit.

91. The method according to claim 81, further comprising the step of creating a number of databases containing envelopes that correspond to the vital sign parameters of one or more of the following of gender, age, height, weight, and race.

92. The method according to claim 91, further comprising the step of comparing the generated signal with the envelopes contained in the database.

93. The method of claim 81, further comprising the step of creating a database containing envelopes that correspond to the vital sign parameters of a single person.

94. The method of claim 93, further comprising the step of comparing the generated signal with the envelopes contained in the database.

95. The method according to claim 81, further comprising the step of comparing the generated signal with the envelopes to determine the performance of the cardiovascular and pulmonary systems in the biological entity.

96. The method according to claim 80, further comprising the step of generating a second signal from the sensor assembly corresponding to at least one characteristic of blood flow Through the biological entity.

97. The method according to claim 96, further comprising the step of analyzing the second generated signal to determine vital sign parameters in the biological entity.

98. The method according to claim 96, wherein the second signal is generated from a different location of the biological entity than the signal.

99. The method according to claim 98, further comprising the step of comparing the generated signal with the second generated signal to identify changes in vital sign parameters in the biological entity.

100. The method according to claim 96, further comprising the steps of determining respiration rate in the biological entity by detecting rhythmic changes in blood oxygen saturation corresponding to respiration rate.

101. The method according to claim 80, further comprising the step of determining blood oxygen saturation from the generated signal in the biological entity.

102. The method according to claim 80, further comprising the step of creating a Myocardial Contractility Index based on multiple Myocardial Contractility measurements.

103. The method according to claim 80, wherein analyzing the signal includes calculating the area under a first portion of the curve of the generated signal to determine Tissue Perfusion.

104. The method according to claim 103, further comprising the step of creating a Tissue Perfusion Index based on multiple Tissue Perfusion measurements.

105. The method according to claim 80, wherein analyzing the signal includes calculating the area under a second portion of the curve of the generated signal to determine Vascular Elasticity.

106. The method according to claim 105, further comprising the step of creating a Vascular Elasticity Index based on multiple Vascular Elasticity measurements.

107. The method according to claim 80, wherein the second signal is an electrocardiogram (EKG) signal.