Compact apparatus and methods for non-invasively measuring hemodynamic parameters

• US 20060079792A1
• Filed: 10/07/2004
• Published: 04/13/2006
• Est. Priority Date: 10/07/2004
• Status: Active Grant

• Current Assignee: Zhejiang Shanshi Biological Medical Devices Company Limited
• Original Assignee: Tensys Medical Inc. (Recorders & Medicare Systems Pvt Ltd.)
• Inventors: Hempstead, Russell D., Finburgh, Simon E., Perona, Mark W.
• Granted Patent: US 7,946,994 B2
• Time in Patent Office: Days
• US Class Current: 600/485
• CPC Class Codes: A61B 5/022 by applying pressure to close blood vessels, e.g. against the skin; Ophthalmodynamometers
• CPC Class Codes: A61B 5/061 Determining position of a probe within the body employing means separate from the probe, e.g. sensing internal probe position employing impedance electrodes on the surface of the body A61B1/00158 takes precedence
• CPC Class Codes: A61B 5/681 Wristwatch-type devices

Abstract

Improved apparatus and methods for non-invasively assessing one or more hemodynamic parameters associated with the circulatory system of a living organism. In one aspect, the invention comprises spatially compact “bracelet” embodiment adapted to accurately place and maintain a sensor (e.g., tonometric pressure sensor) with respect to the anatomy of the subject, including an optional alignment apparatus which moveably captures the sensor to, inter alia, facilitate coupling thereof to an actuator used to position the sensor during measurements. The alignment apparatus also advantageously allows the sensor position to be maintained when the fixture is removed from the subject, such as during patient transport. A completely autonomous variant of the bracelet apparatus having internal power supply and wireless interfaces is also disclosed. Methods for positioning the alignment apparatus and sensor and providing treatment to the subject are also described.

Claims

1. Non-invasive continuous blood pressure measurement apparatus adapted for use on the radial artery of a living subject, comprising:

an articulated body adapted to fit over a substantial fraction of the circumference of the subject'"'"'s wrist area;

a sensor assembly having at least one pressure sensor adapted to sense pressure data from said artery of said subject through tissue overlying said artery;

a sensor actuator substantially received within said articulated body and adapted to movably position said at least one pressure sensor relative to said tissue and said artery;

a support element adapted to at least support said at least one sensor prior to coupling to said actuator, and also engage at least a portion of said articulated body; and

a brace adapted for fitting on at least a portion of said wrist area, said brace and said articulated body being in movable communication with each other;

wherein said brace, support element, body, actuator and sensor cooperate to provide a substantially rigid and stable platform for said continuous blood pressure measurement.

2. The apparatus of claim 1, wherein said articulated body further comprises a central pivot assembly, said pivot assembly comprising at least two axes of rotation around which respective portions of said body can rotate.

3. The apparatus of claim 1, wherein said support element comprises a frame adapted to be fit over at least a portion of said wrist area.

4. The apparatus of claim 3, wherein said support element further comprises a removable element which couples said at least one sensor to said frame.

5. The apparatus of claim 1, further comprising apparatus adapted to determine a proper preload level for said at least one sensor.

6. The apparatus of claim 1, wherein said body forms a substantial “

U”

shape in profile when disposed on said wrist area.

7. The apparatus of claim 1, further comprising a wireless data interface to an external device.

8. Apparatus adapted to monitor blood pressure from a limb of a living subject, comprising:

at least one sensor adapted to generate first signal relating to the pressure applied thereto;

a substantially U-shaped body adapted to adjustably clamp onto said limb proximate a blood vessel of interest;

an actuator coupled to said at least one sensor and said body, said actuator being adapted to controllably applanate said at least one sensor against the tissue of said limb proximate said blood vessel; and

a signal interface adapted to transfer second signals to an external device, said external device being adapted to generate an estimate of said blood pressure based at least in part on said second signals.

9. The apparatus of claim 8, wherein said second signals comprise signals different from said first signals.

10. The apparatus of claim 9, wherein said first signals are signal-processed within said apparatus to produce said second signals.

11. The apparatus of claim 10, wherein said apparatus produces third signals from said first signals, said third signals being in the digital domain, said third signals subsequently being converted to said second signals, said second signals being in the analog domain.

12. The apparatus of claim 11, wherein said second signals comprise signals having a particular format, said format being determined at least in part by said signal interface based on information obtained from said external device.

13. The apparatus of claim 8, wherein said second signals comprise signals having a particular format, said format being determined at least in part by said signal interface based on information obtained from said external device.

14. Selectively controllable pivot apparatus, comprising:

at least first and second movable components, said components being rotatably disposed around respective ones of at least first and second axes;

at least one control mechanism adapted to selectively control the motion of said at least first and said components; and

an actuator mechanism, operatively coupled to said locking[SF3] mechanism, said actuator allowing selective control of said motion of at least first and second components by movement thereof.

15. The pivot apparatus of claim 14, wherein said selective control of motion comprises permitting substantially only two states of operation.

16. The pivot apparatus of claim 15, wherein said two states comprise a locked state and an unlocked state, said unlocked state allowing rotation of said components, said locked state substantially frustrating rotation thereof.

17. The pivot apparatus of claim 14, wherein said at least one control mechanism comprises at least one frictional clutch assembly.

18. The pivot apparatus of claim 17, wherein said clutch assembly comprises at least first, second and third pluralities of plates, said first and second pluralities cooperating with said third plurality to control the rotation of said at least first and second components.

19. The pivot apparatus of claim 14, wherein said actuator mechanism comprises at least a sliding bar having at least first and second eccentric regions disposed thereon.

20. The pivot apparatus of claim 14, wherein said at least one control mechanism comprises a clutch mechanism having a plurality of plates, said plates being selectively loaded by a plurality of load mechanisms.

21. The pivot apparatus of claim 20, wherein said load mechanisms comprise Belleville springs.

22. The pivot mechanism of claim 14, further comprising apparatus adapted to selectively trigger said actuator.

23. The pivot mechanism of claim 22, wherein said selective triggering comprises actuation of a component external to the pivot mechanism.

24. The pivot mechanism of claim 22, wherein said selective triggering of said actuator further causes an external mechanism to be substantially frustrated from movement.

25. Non-invasive blood pressure measurement apparatus adapted for use on radial artery of a living subject, comprising:

an articulated body adapted to fit over a substantial fraction of the circumference of the subject'"'"'s wrist area;

a sensor assembly having at least one pressure sensor adapted to sense pressure data from said artery;

a sensor actuator adapted to movably position said at least one pressure sensor relative to said tissue and said artery; and

a support element adapted to at least support said at least one sensor prior to coupling to said actuator;

wherein said body and support element further cooperate to stabilize said body.

26. The apparatus of claim 25, wherein said articulated body is articulated in at least three degrees of freedom.

27. The apparatus of claim 26, wherein said at least three degrees of freedom comprise at least three rotational degrees of freedom.

28. The apparatus of claim 27, wherein said at least three degrees of rotational freedom comprise (i) a first degree of rotation around a first axis substantially parallel to the longitudinal axis of the subject'"'"'s forearm;

(ii) a second degree of rotation around a second axis substantially parallel to the longitudinal axis of the subject'"'"'s forearm; and

(iii) a third degree of rotation around a third axis substantially transverse to the longitudinal axis of the subject'"'"'s forearm.

29. The apparatus of claim 25, further comprising a brace fitted to said subject proximate said apparatus and adapted to cooperate with said articulated body to add stability to said apparatus during use.

30. Hemodynamic assessment apparatus, comprising:

a bracelet adapted to receive a portion of the anatomy of a living subject;

actuator apparatus substantially integral with said bracelet and adapted to move a sensor; and

alignment apparatus adapted to mate with a portion of said anatomy, said alignment apparatus configured to maintain a desired orientation of said sensor prior to coupling thereof to said actuator.

31. The apparatus of claim 30, wherein said desired orientation comprises disposing the active surface of said sensor above but not in contact with the surface of the skin of said subject.

32. The apparatus of claim 30, wherein said bracelet comprises a substantially semicircular structure, the effective radius of which can be selectively changed by a user.

33. The apparatus of claim 32, wherein said substantially semicircular structure comprises at least interior and anterior elements configured in movable relation to one another, said actuator being substantially integral with said interior element.

34. The apparatus of claim 30, further comprising a brace fitted to said subject proximate to said bracelet and adapted to cooperate with said bracelet to add stability to said apparatus during use.

35. Hemodynamic assessment apparatus, comprising:

a spatially compact structure adapted to securely receive at least a portion of the anatomy of a living subject, said structure having a plurality of articulated elements, said articulated elements at least allowing said structure to be particularly adapted to said anatomy of said subject;

an alignment apparatus adapted couple to said structure and to receive a sensor at least partly therein; and

a coupling element cooperating with said alignment apparatus and said sensor to initially position the sensor with respect to said anatomical portion;

wherein said coupling element is adapted to be removable from said assessment apparatus to permit variable positioning of said sensor subsequent to said initial positioning.

36. The assessment apparatus of claim 35, further comprising a sensor.

37. The assessment apparatus of claim 35, further comprising an actuator element coupled to said sensor and substantially integral with said structure, said actuator element adapted to provide said variable positioning of said sensor.

38. The assessment apparatus of claim 35, wherein said coupling element is slidably engaged with said alignment apparatus and said sensor.

39. A blood pressure monitoring system, comprising:

at least one pressure sensor adapted to measure a pressure waveform from a blood vessel in the wrist area of a living subject;

an actuator adapted to control the position of said at least one sensor relative to said blood vessel; and

a structure adapted to be worn substantially around said wrist area and to maintain said actuator in a substantially constant position with respect to said blood vessel;

wherein said structure comprises a gap and can be placed on said wrist area by passing at least a portion of said wrist area through said gap.

40. Non-invasive blood pressure monitoring apparatus comprising:

a bracelet-like structure having a sensor; and

signal processing apparatus, said processing apparatus adapted to generate scaled blood pressure signals based on data obtained using said sensor from a living subject, said scaled signals being scaled at least in part using at least one physiologic parameter associated with said subject.

41. The apparatus of claim 40, wherein said at least one physiologic parameter comprises body mass index (BMI).

42. The apparatus of claim 41, wherein said at least one physiologic parameter further comprises wrist circumference.

43. The apparatus of claim 40, wherein said scaled blood pressure signals are derived at least in part from pulse pressure (PP) data.

44. The apparatus of claim 40, wherein said scaled blood pressure signals are generated substantially continuously.

45. The apparatus of claim 40, wherein said signal processing apparatus is contained primarily within said bracelet-like structure.

46. Apparatus adapted to position a sensor relative to a portion of the human anatomy, comprising:

a first contact element;

a second contact element disposed in substantial opposition to said first element and adapted to hold said sensor; and

a third element, said third element being hingedly coupled to said first and second elements, said hinged coupling allowing selective adjustment of said apparatus on said portion of said anatomy.

47. The apparatus of claim 46, wherein said second element further comprises an actuator mechanism operatively coupled to said sensor, said actuator being adapted to move said sensor relative to at least said second element.

48. The apparatus of claim 46, further comprising a brace disposed on said anatomy proximate to said first contact element and adapted to cooperate therewith.

49. Joint apparatus for controlling the position of a hemodynamic sensing apparatus with respect to a living subject, wherein actuation of a single mechanism of said joint apparatus permits adjustment of at least two pivots associated with said sensing apparatus.

50. The apparatus of claim 49, wherein said single mechanism comprises a frictional clutch mechanism, said clutch mechanism controlling the movement of said at least two pivots.

51. Joint apparatus for controlling the position of a hemodynamic sensing apparatus with respect to a living subject, comprising a mechanism adapted to sense the preload applied to said sensing apparatus and selectively lock the position of said apparatus when a desired preload level is reached.

52. Physiologic sensing apparatus, comprising:

at least one pressure sensor; and

a substantially U-shaped support structure adapted to receive at least a portion of the anatomy of a subject therein;

wherein said support structure is adapted to couple at least one force felt by said at least one sensor to said at least portion of said anatomy.

53. The apparatus of claim 52, wherein said support structure comprises a bracelet apparatus adapted to fit substantially over said anatomy portion and be adjusted to substantially conform therewith.

54. The apparatus of claim 52, further comprising an actuator coupled to said at least one sensor, said actuator also being coupled to said support structure so as to transmit said at least one force from said sensor to said support structure.

55. The apparatus of claim 54, wherein said at least one force comprises the reaction force generated by said actuator pressing said at least one sensor against said anatomy.

56. The apparatus of claim 52, wherein said at least portion of said anatomy comprises the forearm, and said coupling of said at least one force to said at least portion of said anatomy comprises transferring said force to the back side of the forearm.

57. The apparatus of claim 52, further comprising a brace, wherein said coupling to said anatomy occurs at least partly via said brace.

58. Sensor actuator apparatus, comprising:

a stationary element;

a plurality of components adapted to move relative to said stationary element, at least one of said components further being adapted for coupling to said sensor; and

at least one motor fixedly mounted to said stationary element and operatively coupled to at least one of said components, said at least one motor being adapted to move said at least one component in at least a first direction while maintaining the attitude of said sensor substantially constant.

59. The apparatus of claim 58, further comprising:

at least one sensor; and

a coupling element adapted to mate with said at least one sensor and at least one of said components;

wherein said coupling is further adapted for selective detachment of said at least one sensor from said at least one component.

60. The apparatus of claim 58, wherein said at least one motor comprises a DC motor having a position encoding unit, said position encoding unit generating signals useful for determining the position of at least one of said components.

61. Apparatus adapted to fit substantially on the wrist of a living subject, comprising:

a first portion;

a second portion;

a third portion coupled to said first and second portions and comprising an actuator mechanism;

wherein said first, second and third portions cooperate to surround a substantial fraction of the circumference of said wrist; and

wherein upon actuation of said actuator mechanism, said first, second an third portions are kept in substantially constant relationship to one another.

62. The apparatus of claim 61, wherein said second portion is articulated to rotate with respect to said third portion, and said actuation of said actuator mechanism substantially frustrates said rotation.

63. The apparatus of claim 62, wherein said second portion is articulated to rotate with respect to said third portion around two different axes, and said actuation of said actuator mechanism substantially frustrates said rotation in both axes.

64. The apparatus of claim 61, further comprising a preload mechanism adapted to trigger said actuator mechanism when a predetermined level of compressive force is applied to said first and second portions contemporaneously.