Pulse wave velocity determination, for example for blood pressure monitoring

Patent metadata

Field	Value
Publication number	US-10898085-B2
Application number	US-201716467732-A
Country	US
Kind code	B2
Filing date	Dec 6, 2017
Priority date	Dec 9, 2016
Publication date	Jan 26, 2021
Grant date	Jan 26, 2021

Abstract

A pressure distribution profile of a subject lying on a mat is used to derive a measure of pulse wave velocity. Beat locations are identified where beat pressure signals are identified, and pulse timing information is obtained from the beat locations. By determining a subject posture, the beat locations are mapped to anatomical body locations and arterial path length information is obtained for the anatomical body locations. A pulse wave velocity is then estimated from the pulse timing information and arterial path lengths. This method enables measuring the pulse wave velocity during sleep in a comfortable, easy and unconstrained manner. This is accomplished by analyzing signals from a pressure sensitive surface for example on top of a bed mattress or by embedding a pressure sensitive layer in the mattress.

First claim

The invention claimed is:

1. A method of analyzing a pressure distribution profile (P) of a spatial distribution of pressure over time of a subject lying on a pressure mat to derive a measure of pulse wave velocity of blood in the subject, wherein the method comprises:
identifying beat locations in the subject where beat pressure signals are identified;
obtaining pulse timing information from the beat locations;
determining from the pressure distribution profile (P) a subject posture and mapping the beat locations to anatomical body locations of the subject according to that posture;
determining an arterial path length for the anatomical body locations; and
estimating a pulse wave velocity from the pulse timing information and arterial path length.

2. A method as claimed in claim 1 , comprising obtaining pulse timing information from the beat locations by analyzing each beat pressure signal to determine a start and end of a cardiac cycle and pulse arrival moment at each beat location within a given cardiac cycle.

3. A method as claimed in claim 2 , wherein the pulse arrival moment is obtained based on detecting a pulse onset during a systolic phase.

4. A method as claimed in claim 3 , comprising detecting the pulse arrival moment when a pressure gradient reaches a maximum during the systolic phase.

5. A method as claimed in claim 2 , comprising obtaining the pulse arrival moment for each beat location and each cardiac cycle.

6. A method as claimed in claim 2 , wherein obtaining pulse timing information comprises obtaining a set of pulse delay estimates based on a difference between pulse arrival moments for a set of pairs of beat locations.

7. A method as claimed in claim 2 , further comprising receiving a body motion signal (BCG (t)) indicative of heart activity in respect of the subject, wherein obtaining pulse timing information comprises obtaining a set of pulse transit times (PTT(k)) for a set of beat locations based on the pulse arrival moments for a set of beat locations and the body motion signal.

8. A method as claimed in claim 7 , comprising detecting a peak in the body motion signal and determining a time difference between a timing of a peak and a pulse arrival time for each beat location.

9. A method as claimed in claim 1 , wherein obtaining a subject posture comprises matching the pressure distribution profile (P) to a set of predefined reference human form models.

10. A method as claimed in claim 9 , wherein determining the arterial path length for the anatomical body locations comprises mapping the beat location to the matched human form model.

11. A method as claimed in claim 1 , comprising providing an average pulse wave velocity for a processed set of cardiac cycles.

12. A method as claimed in claim 1 , further comprising deriving from the pulse wave velocity one or more of:
a blood pressure measure;
a measure of arterial stiffness; and
a breathing rate.

13. A computer program comprising computer program code means which is adapted, when said computer program is run on a computer, to implement the method of claim 1 .

14. A monitoring system comprising:
a pressure sensitive mat for providing a pressure distribution profile (P) of a spatial distribution of pressure over time of a subject lying on the pressure sensitive mat; and
a controller for analyzing the pressure distribution profile to derive a measure of pulse wave velocity of the subject,
wherein the controller is adapted to perform the method as claimed in claim 1 .

15. A monitoring system as claimed in claim 14 , further comprising an acceleration sensor for obtaining a body motion signal (BCG(t)).

Assignees

• Koninklijke Philips Nv

Inventors

• De Groot Koen Theo Johan
• Radha Mustafa Ghassan
• Gelissen Jozef Hubertus
• Haakma Reinder

Classifications

• A61B5/02007

  Evaluating blood vessel condition, e.g. elasticity, compliance · CPC title

• A61B5/1113

  Local tracking of patients, e.g. in a hospital or private home · CPC title

• A61B5/0816

  Measuring devices for examining respiratory frequency (measuring frequency of electric signals G01R23/00) · CPC title

• A61B5/0285 Primary

  Measuring or recording phase velocity of blood waves · CPC title

• A61B5/1036

  Measuring load distribution, e.g. podologic studies · CPC title