Apparatuses and methods for non-invasively monitoring blood parameters

• US 20060074283A1
• Filed: 10/05/2004
• Published: 04/06/2006
• Est. Priority Date: 10/05/2004
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: The Theron Technologies LLC
• Inventors: Henderson, Leslie G., Bailey, Theodore M.
• Granted Patent: US 7,341,560 B2
• Time in Patent Office: Days
• US Class Current: 600/315
• 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. An apparatus for monitoring vital sign parameters in a biological entity, comprising:

at least one light source;

at least one photodetector positioned to receive light transmitted through the biological entity from the light source, the at least one light source and at least one photodetector configured to be positioned proximate the biological entity in a manner that does not significantly impede blood flow through the biological entity;

a signal generated in response to the transmittance or reflectance of light through the biological entity, the signal corresponding to at least one characteristic of the generally unimpeded blood flow through the biological entity; and

a control system configured to analyze the signal to determine vital sign parameters of the biological entity.

2. The apparatus of claim 1, wherein the control system includes a number of reference envelopes, the control system configured to compare the generated signal to the number of reference envelopes to determine vital sign parameters of the biological entity.

3. The apparatus of claim 2, wherein the control system includes a number of reference characteristics associated with the reference envelopes, the control system configured to compare the blood flow characteristics associated with the generated signal to the reference characteristics associated with the number of reference envelopes to determine vital sign parameters of the biological entity.

4. The apparatus of claim 1, wherein the control system is configured to process the signal in accordance with an algorithm to determine vital sign parameters of the biological entity.

5. The apparatus of claim 1, wherein the control system is configured to continuously or near-continuously analyze the signal to provide a continuous or near-continuous determination of vital sign parameters of the biological entity.

6. The apparatus of claim 1, wherein the control system is configured to analyze the signal based on the occurrence of a predetermined characteristic in the signal.

7. The apparatus of claim 6, wherein the predetermined characteristic includes a deviation or fluctuation in the signal.

8. The apparatus of claim 1, wherein vital sign parameters include one or more of blood pressure, pulse rate, oxygen saturation, and respiration.

10. The apparatus of claim 1, wherein the light source and photodetector are included in a cuff that is configured to be positioned proximal to the biological entity in a manner that does not significantly impede blood flow through the biological member.

11. The apparatus of claim 10, wherein the cuff includes a selectively inflatable bladder.

12. The apparatus of claim 1, wherein the light source and photodetector are included in a patch that is configured to be positioned proximal to the biological entity in a manner that does not significantly impede blood flow through the biological member.

13. The apparatus of claim 11, wherein the patch includes a selectively inflatable bladder.

14. The apparatus of claim 1, wherein the light source and photodetector are included in a clip that is configured to be positioned proximal to the biological entity in a manner that does not significantly impede blood flow through the biological member.

15. The apparatus of claim 1, wherein the apparatus comprises a second signal generated in response to the transmittance of light through the biological entity, the second signal corresponding to at least one characteristic of the generally unimpeded blood flow through the biological entity.

16. The apparatus of claim 15, wherein the control system is configured to analyze the second signal to determine vital sign parameters of a biological entity.

17. The apparatus of claim 16, wherein the second signal is generated at a different location of the biological entity than the first signal.

18. The apparatus of claim 17, wherein the control system is configured to compare the generated signal with the second generated signal to identify changes in vital sign parameters of the biological entity.

19. The apparatus of claim 1, wherein the generated signal is sent to the control system through transmission wires.

20. The apparatus of claim 1, wherein the generated signal is sent to the control system by radio frequency.

9. The apparatus of claim 9, wherein the blood pressure parameter includes one of diastolic blood pressure, systolic blood pressure and mean arterial blood pressure.

21. 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; and

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

22. The method according to claim 21, 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.

23. The method according to claim 22, further comprising the step of setting the sampling period.

24. The method according to claim 22, further comprising the steps of setting the lower band limit and the upper band limit.

25. The method according to claim 23, wherein the sampling period is determined by an operator.

26. The method according to claim 23, wherein the sampling period is determined by the control system and is based on historical data.

27. The method according to claim 24, wherein the sampling period is determined by an operator.

28. The method according to claim 24, wherein the sampling period is determined by the control system and is based on historical data.

29. The method according to claim 22, comprising the step of employing the reference envelope to monitor subsequent generated signals.

30. The method according to claim 29, further comprising the step of analyzing the generated signal to determine when the generated signal crosses the upper band limit.

31. The method according to claim 29, further comprises the step of analyzing the generated signal to determine when the generated signal crosses the lower band limit.

32. The method according to claim 22, 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.

33. The method according to claim 32, further comprising the step of comparing the generated signal with the envelopes contained in the database.

34. The method of claim 22, further comprising the step of creating a database containing envelopes that correspond to the vital sign parameters of a single person.

35. The method of claim 34, further comprising the step of comparing the generated signal with the envelopes contained in the database.

36. The method according to claim 21, further comprises the step of generating a second signal from the sensor assembly corresponding to at least one characteristic of blood flow through the biological entity.

37. The method according to claim 36, further comprising the step of analyzing the second generated signal to determine vital sign parameters in the biological entity.

38. The method according to claim 36, wherein the second signal is generated from a different location of the biological entity than the signal.

39. The method according to claim 38, 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.

40. The method according to claim 21, further comprising the step of determining blood oxygen saturation from the generated signal in the biological entity.

41. The method according to claim 36, further comprising the steps of determining respiration rate in the biological member by detecting rhythmic changes in blood oxygen saturation corresponding to respiration rate.

42. The method according to claim 22, 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.

43. The method according to claim 21, wherein analyzing the signal includes calculating the upward slope of the generated signal to determine Myocardial Contractility.

44. The method according to claim 43, further comprising the step of creating a Myocardial Contractility Index based on multiple Myocardial Contractility measurements.

45. The method according to claim 21, wherein analyzing the signal includes calculating the area under a first portion of the curve of the generated signal to determine Tissue Perfusion.

46. The method according to claim 45, further comprising the step of creating a Tissue Perfusion Index based on multiple Tissue Perfusion measurements.

47. The method according to claim 21, wherein analyzing the signal includes calculating the area under a second portion of the curve of the generated signal to determine Vascular Elasticity.

48. The method according to claim 47, further comprising the step of creating a Vascular Elasticity Index based on multiple Vascular Elasticity measurements.

49. The method according to claim 21, 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.

50. The method according to claim 49, wherein the second signal is an electrocardiogram (EKG) signal.

51. 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 member;

progressively obstructing blood flow through the biological member;

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

analyzing the signal to determine blood pressure in the biological member.

52. The method according to claim 51, 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.

53. The method of claim 52, 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.

54. The method according to claim 53, 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 and empirically determined constant.

55. The method according to claim 53, 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 and empirically determined constant.

56. The method according to claim 51, wherein progressively obstructing blood flow through the biological member includes:

applying pressure to the biological member at a first rate;

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

relieving the pressure on the biological member.

57. The method according to claim 56, wherein relieving the pressure on the biological member is further defined by relieving the pressure at a second rate that is substantially equal to the first rate.

58. The method according to claim 56, wherein analyzing the signal includes:

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

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

59. The method according to claim 58, 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.

60. The method according to claim 51, further including the step of determining a heart rate in the biological member prior to progressively obstructing blood flow through the biological member.

61. The method according to claim 51, 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.

62. The method according to claim 61, further comprising the step of setting the sampling period.

63. The method according to claim 61, further comprising the steps of setting the lower band limit and the upper band limit.

64. The method according to claim 62, wherein the sampling period is determined by an operator.

65. The method according to claim 62, wherein the sampling period is determined by the control system and is based on historical data.

66. The method according to claim 63, wherein the sampling period is determined by an operator.

67. The method according to claim 63, wherein the sampling period is determined by the control system and is based on historical data.

68. The method according to claim 61, wherein analyzing the signal to determine blood pressure in the biological member includes comparing the generated signal to a reference envelope.

69. The method according to claim 68, further comprising the step of analyzing the generated signal to determine when the generated signal crosses the upper band limit.

70. The method according to claim 68, further comprises the step of analyzing the generated signal to determine when the generated signal crosses the lower band limit.

71. The method according to claim 68, wherein analyzing the signal to determine blood pressure in the biological member includes continuously or near-continuously analyzing the signal to provide a continuous or near-continuous determination of blood pressure in the biological member.

72. The method according to claim 61, further comprising the step of analyzing the reference envelope to identify a peak amplitude that is equal to mean arterial pressure.

73. The method according to claim 61, 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.