METHODS, APPARATUS AND SENSOR FOR MEASUREMENT OF CARDIOVASCULAR QUANTITIES

• US 20110224529A1
• Filed: 11/18/2009
• Published: 09/15/2011
• Est. Priority Date: 11/18/2008
• Status: Active Grant

• Current Assignee: Philips Healthcare Informatics Incorporated (Koninklijke Philips N.V.)
• Original Assignee: Sense Corp (CGI, Inc.)
• Inventors: Lading, Lars
• Granted Patent: US 9,138,161 B2
• Time in Patent Office: Days
• US Class Current: 600/384
• CPC Class Codes: A61B 2562/0214 Capacitive electrodes
• CPC Class Codes: A61B 5/02007 Evaluating blood vessel condition, e.g. elasticity, compliance
• CPC Class Codes: A61B 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/02116 of pulse wave amplitude A61B5/02225 takes precedence
• CPC Class Codes: A61B 5/02125 of pulse wave propagation time
• CPC Class Codes: A61B 5/053 Measuring electrical impedance or conductance of a portion of the body
• CPC Class Codes: A61B 5/681 Wristwatch-type devices
• CPC Class Codes: A61B 5/6822 Neck
• CPC Class Codes: A61B 5/6824 Arm or wrist
• CPC Class Codes: A61B 5/6833 Adhesive patches

Abstract

The present disclosure relates to methods, apparatus and sensor for measurement of cardiovascular quantities. In particular, a method for determining one or more cardiovascular quantities is disclosed, the method comprising determining the distension of a vessel enclosed by tissue having a skin surface, wherein determining the distension is based on a first sensor signal indicating capacitance variations between a first electrode and a second electrode; determining the vascular stiffness of the vessel; and determining the blood pressure based on the distension and the vascular stiffness of the vessel.

Claims

1-37. -37. (canceled)

38. A method for determining one or more cardiovascular quantities, comprising at least vascular stiffness of a vessel of a living being, the vessel being enclosed by tissue having a skin surface, the method comprising:

recording a first sensor signal indicating capacitance variations between a first electrode and a second electrode provided by positioning said first electrode at a first electrode position on the skin surface and positioning said second electrode at a second electrode position on the skin surface such that lines of flux between the first electrode and the second electrode substantially extend through said vessel for determining the distension of the vessel based on at least said first sensor signal,

recording a second sensor signal indicating capacitance variations between electrodes, provided by positioning at least a third electrode displaced at a predetermined distance (d_ppv) from said second electrode at a third electrode position on the skin surface, such that lines of flux substantially extend through the vessel between electrodes comprising said third electrode,

wherein the first and second sensor signal are temporally displaced with a delay (τ

),

determining a pulse propagation velocity (ν

) based on a calculation of said predetermined distance (d_ppv) divided by said delay (τ

) between said first sensor signal and said second sensor signal, and

determining said vascular stiffness of said vessel based on the performed measurements of said pulse propagation velocity (ν

).

39. A method according to claim 38, further comprising determining the blood pressure based on a combination of said determination of vascular stiffness of the vessel and said determination of the distension of said vessel.

40. A method according to claim 39, further comprising determining vascular compliance based on corresponding values of said distension and said blood pressure.

41. A method according to claim 38, wherein recording the second sensor signal comprises positioning a third electrode at a third electrode position on the skin surface such that lines of flux between the third electrode and said second electrode substantially extend through the vessel, the second sensor signal indicating capacitance variations between the second electrode and the third electrode.

42. A method according to claim 38, wherein recording the second sensor signal comprises positioning a third electrode at a third electrode position on the skin surface and a fourth electrode at a fourth electrode position on the skin surface such that lines of flux between the third electrode and the fourth electrode substantially extend through the vessel, the second sensor signal indicating capacitance variations between the third electrode and the fourth electrode.

43. A method according to claim 38, wherein the first and second electrode is positioned upstream or downstream of the vessel from said at least third electrode.

44. A method according to claim 38, wherein the first electrode position is at the inner wrist and the second electrode position is the outer wrist or alternatively wherein the first electrode position and the second electrode position both are on the neck.

57. A blood pressure measurement system for determining one or more cardiovascular quantities, comprising at least vascular stiffness of a vessel of a living being, the vessel being enclosed by tissue having a skin surface, comprising:

a sensor according to claim 45, and

an apparatus comprising a user interface, a processor connected to the user interface, and a memory connected to the processor, wherein the processor is configured for determining the distension of a vessel, and a reading unit for reading one or more sensor signals from said sensor,

wherein the system is configured to performing the method according to claim 38, and the processor is configured determining a pulse propagation velocity (ν

) based on a calculation of said predetermined distance (d_ppv) divided by said delay (τ

) between said first sensor signal and said second sensor signal, and

wherein said processor further is adapted for determining vascular stiffness based on the performed determination of the pulse propagation velocity (ν

).

58. A system according to claim 57, said processor further being configured for determining the blood pressure based on the distension and the vascular stiffness of said vessel.

59. A system according to claim 58, said processor further being configured for determining vascular compliance based on corresponding values of the distension and the blood pressure.

45. A sensor for determining one or more cardiovascular quantities, comprising at least vascular stiffness of a vessel of a living being, the vessel being enclosed by tissue having a skin surface, comprising:

said sensor being adapted for providing at least a first sensor signal indicating capacitance variations between electrodes by comprising a first electrode at a first position and a second electrode at a second position such that during use lines of flux between the first electrode and the second electrode substantially extend through said vessel, and said sensor comprising a readout circuit having a first connection to the first electrode and a second connection to the second electrode, the readout circuit being configured for recoding changes in capacitance between the first electrode and the second electrode, for a determination of the distension of the vessel based on at least said first sensor signal,

said sensor being adapted for providing a second sensor signal indicating capacitance variations between electrodes, wherein at least a third electrode is provided at a third electrode position and positioned at a predetermined distance (d_ppv) from said second electrode, such that during use lines of flux substantially extend through the vessel between electrodes comprising said third electrode, and said at least third electrode having a third connection to said readout circuit, the readout circuit being configured for recording changes in capacitance between the third electrode and the second electrode,

wherein the sensor is adapted such that said first and second sensor signal are temporally displaced with a delay (τ

),

wherein said sensor signals are suitable for performing determination of a pulse propagation velocity (ν

) based on a calculation of said predetermined distance (d_ppv) divided by said delay (τ

) between said first sensor signal and said second sensor signal, and

wherein said sensor signals further are suitable for determining vascular stiffness based on the performed determination of the pulse propagation velocity (ν

).

46. A sensor according to claim 45, wherein the shortest distance (d_ppv) between said first electrode and third electrode is larger than 2 mm, preferably larger than 4 mm, e.g. 10 mm.

47. A sensor according to claim 45, comprising a carrier carrying said first electrode and said second electrode.

48. A sensor according to claim 47, wherein the shortest distance between the first electrode and the second electrode along the carrier is at least 3 cm.

49. A sensor according to claim 45, having a first electrically insulating layer with a first surface wherein the first electrically insulating layer is insulating the first electrode and the second electrode from the first surface.

50. A sensor according to claim 49, wherein the carrier comprises a second layer and the first electrode and the second electrode are arranged between the first electrically insulating layer and the second layer.

51. A sensor according to claim 49, wherein the first electrode and the second electrode are embedded in the first electrically insulating layer.

52. A sensor according to claim 47, wherein the first surface of the carrier has an adhesive coating.

53. A sensor according to claim 45, wherein the first electrode and the second electrode are formed as plate electrodes of metal sheets having an area from 10 mm² to 1600 mm², preferably around 1000 mm².

54. A sensor according to claim 47, wherein the first and second electrode and the at least third electrode are embedded in a common carrier.

55. A sensor according to claim 45, wherein the sensor is flexible and capable of substantially contouring to the skin surface of a living being.

56. A sensor according to claim 45, comprising additional electrodes, e.g. adapted for reference measurements, positioned such that main field lines do not extend through large arteries, veins or parts disturbing measurements.