Wearable blood pressure monitoring system

• US 10,531,797 B2
• Filed: 09/19/2016
• Issued: 01/14/2020
• Est. Priority Date: 09/19/2016
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Knickerbocker, John U., Lee, Hyung-Min, Lee, Kang-Wook
• Primary Examiner(s): Marlen, Tammie K
• Application Number:
  US15/269,040
• Publication Number:
  US 20180078153A1
• Time in Patent Office: 1,212 Days
• CPC Class Codes: A61B 5/002 Monitoring the patient using a local or closed circuit, e.g. in a room or building A61B5/0017 takes precedence
• CPC Class Codes: A61B 5/0022 Monitoring a patient using a global network, e.g. telephone networks, internet
• CPC Class Codes: A61B 5/02007 Evaluating blood vessel condition, e.g. elasticity, compliance
• 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 5/318 Heart-related electrical modalities, e.g. electrocardiography [ECG]
• CPC Class Codes: A61B 5/681 Wristwatch-type devices
• CPC Class Codes: A61B 5/7282 Event detection, e.g. detecting unique waveforms indicative of a medical condition A61B5/4094, A61B5/4818, A61B5/349, A61B5/0823 take precedence

Abstract

An apparatus includes one or more memories storing computer readable code and processor(s). The processor(s), in response to loading and executing the computer readable code, cause the apparatus to perform operations including receiving electrocardiogram data from an electrocardiogram sensor. The electrocardiogram data includes data from an electrocardiogram from a person. The operations also include receiving pulse wave data from one or more pulse wave pressure sensors. The pulse wave data includes data from one or more pulse waves from the person. The operations further include determining blood pressure using the electrocardiogram data or the pulse wave data from the chest and the pulse wave data from the wrist or finger, and outputting an indication of the blood pressure. Another apparatus uses pulse wave data from two pulse wave sensors (e.g., pulse wave pressure sensor(s) and/or PPG sensor(s)) and blood pressure determinations are made using these pulse wave data.

Claims

1. An apparatus comprising:

at least one pulse wave pressure sensor where pulse wave data is received from, wherein receiving of the pulse wave data is via one of a wireless or wired interface, wherein the at least one pulse wave pressure sensor comprises a layered structure configured, in response to pulse waves in a person, to generate electronic pulse waves in a form of a capacitance versus time;

an electrocardiogram sensor where electrocardiogram data is received from, wherein the receiving of the electrocardiogram data is via one of a wireless or wired interface; and

one or more memories storing computer readable code; and

one or more processors, wherein the one or more processors, in response to loading and executing the computer readable code, cause the apparatus to perform operations comprising;

receiving electrocardiogram data comprising data from the electrocardiogram sensor;

receiving pulse wave data from the at least one pulse wave pressure sensor, the pulse wave data comprising data from one or more pulse waves from the person;

determining blood pressure using at least the electrocardiogram data and the pulse wave data; and

outputting an indication of the blood pressure.

2. The apparatus of claim 1, wherein the at least one pulse wave pressure sensor further comprises:

a sensor structure, comprising;

a first portion configured to contact the person at a skin surface of the person where the sensor structure is capable of taking readings concerning arteries or veins or both thereunder;

a second portion that contacts the first portion and is configured to have a capacitance,

wherein a pulse pressure under the skin causes squeezing or bending between the first portion and a fixed part of the second portion, and

wherein the first and second portions are configured to create a capacitance change in response to the squeezing or bending caused by the pulse pressure in relation to a return to an original state of the first portion with a release of the pulse pressure; and

circuitry connected to the sensor structure and configured to measure and transmit a waveform for the sensor structure and configured to digitize the measured waveform, wherein the waveform captures the capacitance change.

3. The apparatus of claim 1, wherein determining blood pressure using at least the electrocardiogram data and the pulse wave data further comprises determining a systolic blood pressure based on pulse transit time (PTT) (SBP_PTT) using the following:

SBP_PTT=a*ln(h²/PTT²)+b,

where h is the person'"'"'s height, a and b are constants which are empirically obtained, PTT is a pulse transit time determined using the electrocardiogram data and the pulse wave data, and ln(⋅

) means natural logarithm, and

wherein PTT is determined as a time between an R peak in the electrocardiogram data and a corresponding maximum inclination in pulse wave data from the at least one pulse wave pressure sensor.

4. The apparatus of claim 3, wherein the one or more processors, in response to loading and executing the computer readable code, further cause the apparatus to perform operations comprising:

outputting an indication of the systolic blood pressure based on pulse transit time (PTT) (SBP_PTT), wherein the outputting is to one or more of a display or a wireless or wired network interface.

5. The apparatus of claim 3, further comprising one or more photoplethysmography sensors.

6. The apparatus of claim 5, wherein at least one of the one or more photoplethysmography sensors comprises a reflection-mode photoplethysmography sensor.

7. The apparatus of claim 3, wherein determining blood pressure using at least the electrocardiogram data and the pulse wave data further comprises determining diastolic blood pressure using the following:

DBP=c*SBP_PTT+dT₂+e,

where c, d and e are constants which are empirically obtained, and T₂ is determined using the pulse wave data from the at least one pulse wave pressure sensor and is a time interval between a peak point of a pulse wave and a baseline point where the pulse wave reaches to the baseline.

8. The apparatus of claim 7, wherein the one or more processors, in response to loading and executing the computer readable code, further cause the apparatus to perform operations comprising:

outputting one or more indications of one or more of the following;

the systolic blood pressure based on pulse transit time (PTT) (SBP_PTT) and the diastolic blood pressure, wherein the outputting is to one or more of a display or a wireless or wired interface.

9. The apparatus of claim 7, further comprising a photoplethysmography sensor.

10. The apparatus of claim 9, wherein photoplethysmography sensor comprises a reflection-mode photoplethysmography sensor.

11. The apparatus of claim 7, wherein determining blood pressure using at least the electrocardiogram data and the pulse wave sensor data further comprises:

determining the systolic blood pressure using the following equation;

SBP=SBP_PTT[1+α

×

SI_DVP],

where SBP is systolic blood pressure, SBP_PTT is the systolic blood pressure based on the pulse transit time (PTT), α

is defined empirically, and SI_DVP is a stiffness index determined using the pulse wave data.

12. The apparatus of claim 11, wherein the one or more processors, in response to loading and executing the computer readable code, further cause the apparatus to perform operations comprising:

outputting one or more indications of one or more of the following;

the systolic blood pressure based on pulse transit time (PTT) (SBP_PTT),

diastolic blood pressure, and the systolic blood pressure, wherein the outputting is to one or more of a display or a wireless or wired network interface.

13. The apparatus of claim 11, wherein the pulse wave data used for determination of the stiffness index is from a photoplethysmography sensor.

14. The apparatus of claim 13, where the photoplethysmography sensor comprises a reflection-mode photoplethysmography sensor.

15. The apparatus of claim 11, wherein the stiffness index SI_DVP is determined using the following:

16. The apparatus of claim 15, further comprising a photoplethysmography sensor, and wherein the pulse wave data used for determination of the stiffness index is from the photoplethysmography sensor.

17. The apparatus of claim 16, where the photoplethysmography sensor comprises a reflection-mode photoplethysmography sensor.

18. The apparatus of claim 15, wherein the one or more processors, in response to loading and executing the computer readable code, further cause the apparatus to perform operations comprising:

outputting one or more indications of one or more of the following;

the systolic blood pressure based on pulse transit time (PTT) (SBP_PTT),

diastolic blood pressure,

the systolic blood pressure, and

the stiffness index,

wherein the outputting is to one or more of a display or a wireless or wired network interface.

19. An apparatus comprising:

an electrocardiogram sensor configured to receive electrocardiogram data, the electrocardiogram data comprising data from an electrocardiogram from a person;

at least one pulse wave pressure sensor configured to receive pulse wave data from one or more pulse waves of the person;

one or more memories storing computer readable code; and

one or more processors, wherein the one or more processors, in response to loading and executing the computer readable code, are configured to cause the apparatus to perform operations comprising;

determining blood pressure, comprising;

determining a systolic blood pressure based on pulse transit time (SBP_PTT) using the following;

SBP_PTT=a*ln(h²/PTT²)+b,

where h is the person'"'"'s height, a and b are constants which are empirically obtained, PTT is a pulse transit time determined using the electrocardiogram data and the pulse wave data, and ln( ) means natural logarithm, and

wherein PTT is determined as a time between an R peak in the electrocardiogram data and a corresponding maximum inclination in the pulse wave data, and

outputting an indication of the determined blood pressure.

20. The apparatus of claim 19, wherein the at least one pulse wave pressure sensor comprises a layered structure configured, in response to pulse waves in the person, to generate electronic pulse waves in a form of a capacitance versus time.

21. The apparatus of claim 19, wherein the at least one pulse wave pressure sensor further comprises:

a sensor structure, comprising;

a first portion configured to contact the person at a skin surface of the person where the sensor structure is capable of taking readings concerning arteries or veins or both thereunder;

a second portion that contacts the first portion and is configured to have a capacitance, wherein a pulse pressure under the skin causes squeezing or bending between the first portion and a fixed part of the second portion, and

wherein the first and second portions are configured to create a capacitance change in response to the squeezing or bending caused by the pulse pressure in relation to a return to an original state of the first portion with a release of the pulse pressure; and

circuitry connected to the sensor structure and configured to measure and transmit a waveform for the sensor structure and configured to digitize the measured waveform, wherein the waveform captures the capacitance change.

22. The apparatus of claim 19, wherein determining blood pressure further comprises determining diastolic blood pressure using the following:

DBP=c*SBP_PTT+dT₂+e,

where c, d and e are constants which are empirically obtained, and T₂ is determined using the pulse wave data from the at least one pulse wave pressure sensor and is a time interval between a peak point of a pulse wave in the pulse wave data and a baseline point where the pulse wave reaches to the baseline.