DETERMINING PULSE TRANSIT TIME NON-INVASIVELY USING HANDHELD DEVICES

• US 20140249398A1
• Filed: 03/04/2013
• Published: 09/04/2014
• Est. Priority Date: 03/04/2013
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Morris, Daniel, Saponas, T. Scott, Tan, Desney S., Dixon, Morgan, Vathsangam, Harshvardhan, Khullar, Siddharth
• Granted Patent: US 9,504,391 B2
• Time in Patent Office: Days
• US Class Current: 600/393
• CPC Class Codes: A61B 2560/0462 Apparatus with built-in sensors
• CPC Class Codes: A61B 5/0077 Devices for viewing the surface of the body, e.g. camera, magnifying lens
• CPC Class Codes: A61B 5/02125 of pulse wave propagation time
• CPC Class Codes: A61B 5/282 Holders for multiple electrodes for introduction into the body A61B5/287
• CPC Class Codes: A61B 5/332 Portable devices specially adapted therefor
• CPC Class Codes: A61B 5/6815 Ear
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal
• CPC Class Codes: A61B 5/7278 Artificial waveform generation or derivation, e.g. synthesising signals from measured signals A61B5/327 takes precedence
• CPC Class Codes: A61B 5/748 Selection of a region of interest, e.g. using a graphics tablet

Abstract

A system and method to determine pulse transit time using a handheld device. The method includes generating an electrocardiogram (EKG) for a user of the handheld device. Two portions of the user'"'"'s body are in contact with two contact points of the handheld device. The method also includes de-noising the EKG to identify a start time when a blood pulse leaves a heart of the user. The method further includes de-noising a plurality of video images of the user to identify a pressure wave indicating an arterial site and a time when the pressure wave appears. Additionally, the method includes determining the PTT based on the de-noised EKG and the de-noised video images.

Claims

1. A method for determining pulse transit time using a handheld device, the method comprising:

generating an electrocardiogram (EKG) for a user of the handheld device, wherein the EKG is generated from two conductive contact points on the handheld device in contact with two portions of the user'"'"'s body;

de-noising the EKG to identify a start time when a blood pulse leaves a heart of the user;

receiving a plurality of video images of the user;

de-noising the plurality of video images of the user to identify a pressure wave indicating an arterial site and a time when the pressure wave appears; and

determining a pulse transit time (PTT) based on the de-noised EKG and the de-noised video images.

3. The method recited in claim 1, wherein one of the conductive contact points comprises a contact point on a conductive touch screen surface of the handheld device.

4. The method recited in claim 1, wherein one of the conductive contact points comprises a contact point on a back of the handheld device.

6. The method recited in claim 1, comprising:

identifying a start time of the PTT, wherein the start time is determined from the de-noised EKG; and

identifying an end time of the PTT, wherein the end time is the time when the pressure wave appears.

7. The method recited in claim 1, comprising:

identifying a facial region of the video images;

identifying a left cheek region of the video images;

identifying a right cheek region of the video images;

generating a red-green-blue (RGB) signal for the facial region, left cheek region, and right cheek region;

performing independent component analysis (ICA) on the RGB signals to generate components of the ICA;

identifying the pressure wave based on a component of the ICA having a lowest Kurtosis of the components of the ICA.

2. The method recited in claim 2, comprising:

determining a blood pressure measurement of the user based on the PTT; and

presenting the blood measurement using the handheld device.

5. The method recited in claim 2, wherein one of the conductive contact points- comprises a contact point on an earphone in communication with the handheld device.

8. A system for determining pulse transit time using a handheld device, the system comprising:

a processing unit; and

a system memory, wherein the system memory comprises code configured to direct the processing unit to;

generate an electrocardiogram (EKG) for a user of the handheld device, wherein the EKG is generated from two conductive contact points on the handheld device in contact with two portions of the user'"'"'s body;

de-noise the EKG to identify a start time when a blood pulse leaves a heart of the user;

receive a plurality of video images of the user;

de-noise the plurality of video images of the user to identify a pressure wave indicating an arterial site and a time when the pressure wave appears; and

determine a pulse transit time (PTT) based on the de-noised EKG and the de-noised video images.

10. The system recited in claim 8, wherein one of the conductive contact points comprises a contact point on a conductive touch screen surface of the handheld device.

11. The system recited in claim 8, wherein one of the conductive contact points comprises a contact point on a back of the handheld device.

12. The system recited in claim 8, wherein one of the conductive contact points comprises a contact point on an earphone in communication with the handheld device.

13. The system recited in claim 8, comprising code configured to direct the processing unit to:

identify a start time of the PTT, wherein the start time is determined from the de-noised EKG; and

identify an end time of the PTT, wherein the end time is the time when the pressure wave appears.

14. The system recited in claim 8, comprising code configured to direct the processing unit to:

identify a facial region of the video images;

identify a left cheek region of the video images;

identify a right cheek region of the video images;

generate a red-green-blue (RGB) signal for the facial region, left cheek region, and right cheek region;

perform independent component analysis (ICA) on the RGB signals to generate components of the ICA;

identify the pressure wave based on a component of the ICA having a lowest Kurtosis of the components of the ICA.

9. (canceled)

15. One or more computer-readable storage memory for determining pulse transit time, the computer-readable storage memory comprising code configured to direct a processing unit to:

generate an electrocardiogram (EKG) for a user of a handheld device, wherein the EKG is generated from two conductive contact points on the handheld device in contact with two portions of the user'"'"'s body;

de-noise the EKG to identify a start time when a blood pulse leaves a heart of the user;

receive a plurality of video images of the user;

de-noise the plurality of video images of the user to identify a pressure wave indicating an arterial site and a time when the pressure wave appears; and

determine a pulse transit time (PTT) based on the de-noised EKG and the de-noised video images.

16. The computer-readable storage memory recited in claim 15, comprising code configured to direct a processing unit to:

determining a blood pressure measurement of the user based on the PTT; and

presenting the blood measurement using the handheld device.

17. The computer-readable storage memory recited in claim 15, wherein one of the conductive contact points comprises a contact point on a conductive touch screen surface of the handheld device, and one of the contact points comprises a contact point on a back or side of the handheld device.

18. The computer-readable storage memory recited in claim 15, comprising code configured to direct the processing unit to:

identify a start time of the PTT, wherein the start time is determined from the de-noised EKG; and

identify an end time of the PTT, wherein the end time is the time when the pressure wave appears.

19. The computer-readable storage memory recited in claim 15, comprising code configured to direct the processing unit to:

identify a facial region of the video images;

identify a left cheek region of the video images;

identify a right cheek region of the video images;

generate a red-green-blue (RGB) signal for the facial region, left cheek region, and right cheek region; and

perform independent component analysis (ICA) on the RGB signals to generate components of the ICA.

20. The computer-readable storage memory recited in claim 15, comprising code configured to direct the processing unit to:

identify an additional facial region of the video image;

perform dimensionality reduction on the additional facial region to generate dimensionally-reduced signals; and

select one of the dimensionally-reduced signals for pulse extraction based on statistical measures of information content.

21. The computer-readable storage memory recited in claim 15, wherein the handheld device comprises a game controller.