Blood Pressure Measurement Using a Wearable Device

• US 20160360974A1
• Filed: 08/02/2016
• Published: 12/15/2016
• Est. Priority Date: 06/12/2015
• Status: Active Grant

• Current Assignee: ChroniSense Medical, Ltd.
• Original Assignee: ChroniSense Medical, Ltd.
• Inventors: Lange, Daniel H.
• Granted Patent: US 11,160,461 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: A61B 5/0006 ECG or EEG signals
• 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 5/0205 Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
• CPC Class Codes: A61B 5/02125 of pulse wave propagation time
• CPC Class Codes: A61B 5/02427 Details of sensor
• CPC Class Codes: A61B 5/1072 measuring distances on the body, e.g. measuring length, height or thickness A61B5/1076 takes precedence
• CPC Class Codes: A61B 5/14546 for measuring analytes not otherwise provided for, e.g. ions, cytochromes
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor
• CPC Class Codes: A61B 5/349 Detecting specific parameters of the electrocardiograph cycle
• CPC Class Codes: A61B 5/6824 Arm or wrist
• CPC Class Codes: A61B 5/7235 Details of waveform analysis A61B5/349 takes precedence

Abstract

Systems and methods for performing a blood pressure measurement are provided. An example method includes simultaneously recording, by a wearable device, an electrocardiogram (ECG) and photoplethysmogram (PPG). PPG is measured at a blood artery. The method also includes analyzing ECG and PPG to determine a pulse transit time (PTT), a pulse rate (PR), and a diameter parameter. The diameter parameter includes a diameter of the blood artery or a change thereof. The method also includes determining, based on PTT, PR, and the diameter parameter, a blood pressure (BP) using a pre-defined model. The pre-defined model establishes a relationship between PTT, PR, the diameter parameter, and BP. The pre-defined model may be trained using statistical data obtained in a calibration process. The statistical data includes PTT, PR, and the diameter parameter measured with the wearable device and corresponding values of BP measured with an external device.

Claims

1. A method for performing a blood pressure (BP) measurement, the method comprising:

recording substantially simultaneously, by a wearable device, an electrocardiogram (ECG) and photoplethysmogram (PPG), wherein the PPG is measured at a blood artery;

analyzing, by at least one processor, the ECG and the PPG to determine a pulse transit time (PTT), a pulse rate (PR), and a diameter parameter, wherein the diameter parameter includes one of a diameter of the blood artery and a change in the diameter of the blood artery; and

determining, by the at least one processor and using a pre-defined model, a BP based on the PTT, the PR, and the diameter parameter, wherein the pre-defined model establishes a relationship between the PTT, the PR, the diameter parameter, and the BP.

2. The method of claim 1, wherein the pre-defined model includes a regression analysis, wherein the PTT, the PR, and the diameter parameter are explanatory variables and the BP is a dependent variable.

3. The method of claim 1, wherein the pre-defined model is trained using statistical data obtained in a calibration process, the statistical data including the PTT, the PR, and the diameter parameter measured with the wearable device and corresponding values of the BP measured with an external device.

4. The method of claim 1, wherein the PTT is determined as a shift in time between a certain feature in the ECG and an associated feature in the PPG, the certain feature and the associated feature corresponding to a same heartbeat.

5. The method of claim 1, wherein the PTT is determined as a shift in time between a first waveform of the ECG and a second waveform in the PPG, the first waveform and the second waveform corresponding to a same heartbeat.

6. The method of claim 1, wherein the PR is determined as a time period between two consecutive peaks in ECG.

7. The method of claim 1, wherein the PPG includes an intensity of a light reflected from the blood artery.

8. The method of claim 7, wherein a wavelength of the light is isosbestic relative to a light absorption by blood in the blood artery.

9. The method of claim 1, wherein the change in the diameter of the blood artery is determined using equation

10. The method of claim 1, wherein the blood artery is a radial artery at a wrist.

11. A system for performing a pulse oximetry, the system comprising:

a wearable device operable to record simultaneously an electrocardiogram (ECG) and photoplethysmogram (PPG), wherein the PPG is measured at a blood artery; and

at least one processor communicatively coupled to the wearable device and operable to;

analyze the ECG and the PPG to determine a pulse transit time (PTT), a pulse rate (PR), and a diameter parameter, the diameter parameter including one of diameter of the blood artery and a change in the diameter of the blood artery; and

determine, based on the PTT, the PR, and the diameter parameter, a blood pressure (BP) using a pre-defined model, wherein the pre-defined model establishes a relationship between the PTT, the PR, the diameter parameter, and the BP.

12. The system of claim 11, wherein the pre-defined model includes a regression equation, wherein the PTT, the PR, and the diameter parameter are explanatory variables and the BP is a dependent variable.

13. The system of claim 11, wherein the pre-defined model is trained using statistical data obtained in a calibration process, the statistical data including the PTT, the PR, and the diameter parameter measured with the wearable device and corresponding values of the BP measured with an external device.

14. The system of claim 11, wherein the PTT is determined as a shift in time between a certain feature in the ECG and an associated feature in the PPG, the certain feature and the associated feature corresponding to a same heartbeat.

15. The system of claim 11, wherein the PTT is determined as a shift in time between a first waveform of the ECG and a second waveform in the PPG, the first waveform and the second waveform corresponding to a same heartbeat.

16. The system of claim 11, wherein the PR is determined as a time period between two consecutive peaks in ECG.

17. The system of claim 11, wherein the PPG includes intensity of a light reflected from the blood artery.

18. The system of claim 17, wherein a wavelength of the light is isosbestic relative to light absorption by blood in the blood artery.

19. The system of claim 11, wherein the change in the diameter of the blood artery is determined using equation

20. A non-transitory computer-readable storage medium having embodied thereon instructions, which when executed by at least one processor, perform steps of a method, the method comprising:

recording, by a wearable device, simultaneously an electrocardiogram (ECG) and photoplethysmogram (PPG), wherein the PPG is measured at a blood artery;

analyzing, by at least one processor, the ECG and the PPG to determine a pulse transit time (PTT), a pulse rate (PR), and a diameter parameter, wherein the diameter parameter includes one of the blood artery and a change in the diameter of the blood artery; and

determining, by the at least one processor and using a pre-defined model, a blood pressure (BP) based on the PTT, the PR, and the diameter parameter, wherein the pre-defined model establishes a relationship between the PTT, the PR, the diameter parameter, and the BP.