BLOOD PRESSURE MONITORING USING A MULTI-FUNCTION WRIST-WORN DEVICE

• US 20170340209A1
• Filed: 08/18/2017
• Published: 11/30/2017
• Est. Priority Date: 09/08/2014
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Klaassen, Erno H., Dougherty, Wren Nancy, Kimoto, Richard C., Narasimhan, Ravi, Sullivan, Thomas J., Waydo, Stephen J., Whitehurst, Todd K., Quijano, Santiago, Young, Derek Park-Shing, Zeng, Zijing
• Granted Patent: US 10,772,512 B2
• Time in Patent Office: Days
• CPC Class Codes: A61B 5/0002 Remote monitoring of patients using telemetry, e.g. transmission of vital signals via a communication network A61B5/07 takes precedence; transmission systems for measured values G08C; transmission H04B; transmission of digital information H04L; wireless communication networks H04W
• 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 5/11 Measuring movement of the entire body or parts thereof, e.g. head or hand tremor, mobility of a limb for measuring pulse A61B5/02 ;A61B5/1038 takes precedence; motion detection to correct for motion artifacts in physiological signals A61B5/721
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/681 Wristwatch-type devices
• CPC Class Codes: A61B 5/6824 Arm or wrist
• CPC Class Codes: G16H 20/00 ICT specially adapted for therapies or health-improving plans, e.g. for handling prescriptions, for steering therapy or for monitoring patient compliance
• CPC Class Codes: G16H 40/67 for remote operation

Abstract

The present invention provides non-invasive devices, methods, and systems for determining a pressure of blood within a cardiovascular system of a user, the cardiovascular system including a heart and the user having a wrist covered by skin. More particularly, the present invention discloses a variety of wrist-worn devices having a variety of sensors configured to non-invasively engage the skin on the wrist of the user for sensing a variety of user signals from the cardiovascular system of the user. Generally, approaches disclosed herein may passively track blood pressure values without any interaction required on the part of the user or may allow for on demand or point measurements of blood pressure values by having a user actively interact with the sensors of the wrist-worn device. Approaches disclosed herein further allow for absolute blood pressure values to be determined directly without the requirement for any periodic calibrations or for relative blood pressure values to be tracked so as to provide relative blood pressure indices.

Claims

1. A method for determining a pressure of blood within a cardiovascular system of a user, the cardiovascular system including a heart and the user having a wrist covered by skin, the method comprising:

receiving a plurality of user signals from the cardiovascular system of the user with a sensor, the sensor non-invasively engaging the skin of the user over the wrist of the user, each of the user signals being received by the sensor while the sensor has an associated height relative to the heart of the user, wherein the user moves the wrist between the signals so that the heights of the sensor differ within a range of heights relative to the heart of the user;

identifying a signal variation amplitude of the plurality of signals associated with the range of heights; and

determining a standard pressure of the blood of the user based on the signal variation amplitude and the plurality of signals, the standard pressure having an associated standard blood pressure measurement height relative to the heart.

2. The method of claim 1, wherein the plurality of user signals comprises volume or pressure waveform signals from at least one photoplethysmogram (PPG) or pressure sensor respectively non-invasively engaging the skin of the user over the wrist.

3. The method of claim 2, wherein identifying the signal variation amplitude further comprises identifying a maximum volume or pressure waveform signal based on an oscillation or amplitude of the plurality of volume or pressure waveform signals of the user.

4. The method of claim 3, wherein a volume or pressure waveform signal associated with the highest oscillation or amplitude comprises the maximum volume or pressure waveform signal.

5. The method of claim 3, further comprising receiving a signal indicative of the height of the sensor relative to the heart associated with the maximum volume or pressure waveform signal.

6. The method of claim 5, wherein receiving a signal indicative of the height of the sensor relative to the heart further comprises calculating a height measurement from at least a height sensor, accelerometer, gyroscope, user input, anthropometric data, or a barometric pressure sensor.

7. The method of claim 5, wherein determining the standard pressure of the blood of the user comprises determining a mean arterial pressure based on the maximum volume or pressure waveform signal and the signal indicative of the height of the sensor relative to the heart associated with the maximum volume or pressure waveform signal.

8. The method of claim 7, further comprising receiving a pressure measurement applied to a radial artery beneath the skin of the wrist of the user for determining the mean arterial pressure, wherein a relatively constant pressure is applied over the radial artery as the at least one PPG or pressure sensor is swept through the range of heights relative to the heart of the user.

9. The method of claim 7, further comprising calibrating non-invasive relative blood pressure signals based on the determined mean arterial pressure of the user.

10. The method of claim 1, wherein the range of heights relative to the heart of the user comprises a range from about 1 cm to about 40 cm.

11. The method of claim 1, further comprising transmitting the determined mean arterial pressure to a second wrist-worn device, mobile device, tablet, computer, or database.

12-33. -33. (canceled)

34. A first wrist-worn device for determining a pressure of blood within a cardiovascular system of a user, the cardiovascular system including a heart and the user having a wrist covered by skin, the device comprising:

an elongate band extending around the wrist and non-invasively engaging the skin on the wrist of the user, wherein the elongate band is releasably coupleable to a second wrist-worn electronic device;

at least one pulse transit time (PTT) or pressure sensor coupled to the elongate band and non-invasively engaging the skin over the wrist of the user for measuring user signals from the cardiovascular system of the user;

a controller coupled to the elongate band and at least one PTT or pressure sensor for determining relative or absolute blood pressure signals based on the user signals;

a power source coupled to the elongate band and the controller or the at least one PTT or pressure sensor; and

a telemetry interface coupled to the elongate band and the controller.

35. The device of claim 34, wherein the second wrist-worn electronic device comprises a watch or heart rate monitor having a housing encasing a second controller, second power source, and second telemetry interface, wherein the elongate band further comprises at least one connection feature for securing the band to the watch or heart rate monitor.

37. The device of claim 34, wherein the at least one PTT sensor comprises:

a first sensor configured to measure a first user signal indicative of ventricular ejection of blood from the heart of the user, the first sensed ventricular ejection signal having an associated ventricular ejection time; and

a second sensor configured to measure a second user signal indicative of arrival of a pressure pulse in the wrist, the second sensed pressure pulse signal associated with the first sensed ventricular ejection and having an associated pulse arrival time, wherein the relative blood pressure signal is determined from a difference between the ventricular ejection time and the pulse arrival time.

38. The device of claim 37, wherein the first sensor comprises at least one impedance cardiogram (ICG), electrocardiogram (ECG), ballistocardiogram (BCG), phonocardiogram (PCG), or seismocardiogram (SCG) sensor coupled to the elongate band.

39. The device of claim 38, wherein the at least one ICG or ECG sensor comprises at least a first pair of dry electrodes configured to non-invasively engage glabrous skin on an anterior surface of the wrist and a second pair of dry electrodes configured to be contacted by at least two fingers of an opposite hand.

40. The device of claim 38, wherein the at least one ICG or ECG sensor comprises at least a first pair of dry electrodes configured to non-invasively engage glabrous skin on an anterior surface of the wrist and a second pair of dry electrodes configured to non-invasively engage a sternum.

41. The device of claim 38, wherein the at least one BCG sensor comprises an accelerometer configured to non-invasively engage an anterior surface of the wrist so as to passively measure a relative blood pressure.

42. The device of claim 38, wherein the at least one PCG sensor comprises a sound sensor configured to non-invasively engage a sternum.

43. The device of claim 38, wherein the at least SCG sensor comprises an accelerometer configured to non-invasively engage a sternum.

44. The device of claim 37, wherein the first sensor comprises first and second cardiogram sensors coupled to the elongate band for sensing the first user signal indicative of ventricular ejection of blood from the heart of the user, wherein the second cardiogram sensor is different than the first cardiogram sensor, wherein the first and second cardiogram sensors comprise an impedance cardiogram (ICG), electrocardiogram (ECG), ballistocardiouram (BCG), phonocardiogram (PCG), or seismocardiogram (SCG) sensor.

46. The device of claim 37, wherein the second sensor comprises at least one photoplethysmogram (PPG) sensor or physical pressure pulse sensor coupled to the elongate band, wherein the at least one PPG sensor comprises at least one infra-red, red, or green optical source and a detector configured to be positioned over a radial artery of the wrist of the user, wherein the physical pressure pulse sensor comprises at least one pressure transducer, accelerometer, or strain gauge configured to be positioned over a radial artery of the wrist of the user.

49. The device of claim 34, wherein the pressure sensor comprises at least one pressure transducer, piezoelectric film, or piezoresistive sensor configured to non-invasively engage an anterior surface of the wrist of the user and be positioned over a radial artery so as to passively or actively measure the absolute blood pressure signals, further comprising at least one actuator coupled to the elongate band and configured to apply a constant or variable pressure over a radial artery of the wrist.

51. The device of claim 34, further comprising at least one height sensor, barometric pressure sensor, gyroscope, or accelerometer coupled to the elongate band so as to account for hydrostatic pressure effects.

52. The device of claim 34, wherein the telemetry interface of the elongate band is configured to transmit the relative or absolute blood pressure signals to the second wrist-worn electronic device, a mobile device, tablet, computer, or database.

53. The device of claim 34, wherein the telemetry interface of the elongate band is configured to transmit the relative or absolute blood pressure signals to an electronic health or medical record or health application software.

54. The device of claim 34, wherein the telemetry interface of the elongate band is configured to transmit the relative or absolute blood pressure signals to a display on the second wrist-worn electronic device or a third non-wrist device, the display viewable by the user or a health care professional.

55. The device of claim 34, wherein the telemetry interface of the elongate band is configured to transmit trending data for a time period based on the relative blood pressure signals, wherein the time period comprises one or more days, weeks, months, or years.

36. (canceled)

45. (canceled)

47-48. -48. (canceled)

50. (canceled)

56-68. -68. (canceled)