Control unit for deriving a measure of arterial compliance

Patent metadata

Field	Value
Publication number	US-12178553-B2
Application number	US-201917416220-A
Country	US
Kind code	B2
Filing date	Dec 9, 2019
Priority date	Dec 18, 2018
Publication date	Dec 31, 2024
Grant date	Dec 31, 2024

Abstract

The invention provides a controller and method for deriving a measure of arterial compliance based on an acquired arterial volume variation signal and an acquired pulse arrival time signal. An oscillometric blood pressure measurement device is used to acquire the arterial volume variation signal. Arterial volume and variation in pulse arrival time are both measured as an applied pressure to an artery are varied by the oscillometric blood pressure measurement device. The arterial volume signal is transformed into a corresponding signal representative of variation in peak-to-peak amplitude of the arterial volume.

First claim

The invention claimed is:

1. A controller for deriving a measure of arterial compliance, operably couplable in use with an oscillometric blood pressure measurement device,
the controller adapted to:
receive, from the oscillometric blood pressure measurement device, an arterial volume signal indicative of a variation in arterial volume of an artery assumed to be in contact with the measurement device, as a pressure applied to the artery by the measurement device is varied across a range of pressures;
extract from said arterial volume signal a peak-to-peak volume amplitude signal indicative of a peak-to-peak amplitude of the arterial volume across said range of applied pressures;
receive a signal indicative of a variation in pulse arrival time at a particular location along said artery as said applied pressure is varied across said range of pressures;
derive from said extracted peak-to-peak volume amplitude signal, a signal, V a-osc , indicative of arterial volume as a function of arterial transmural pressure, based on a first model fitting procedure employing a pre-determined arterial volume model; and
derive an output measure indicative of arterial compliance based on the derived V a-osc signal and based on the acquired signal indicative of variation in pulse arrival time, using a further model fitting procedure employing a pre-determined pulse arrival time model relating variation in pulse arrival time, arterial volume, and arterial compliance.

2. The controller as claimed in claim 1 , wherein the pulse arrival time model is based on a relationship between pulse arrival time and pulse wave velocity, and a relationship between pulse wave velocity, arterial volume and arterial compliance.

3. The controller as claimed in claim 1 , wherein the V a-osc signal is used to inform fitting of the pulse arrival time model.

4. The controller as claimed in claim 1 , wherein the further model fitting procedure comprises:
iteratively generating different sample functions of arterial volume as a function of transmural pressure and of arterial compliance as a function of arterial pressure;
generating, using the pulse arrival time model, a corresponding modeled function of pulse arrival time for each sample arterial volume function, and
in each case comparing the resulting modeled function of pulse arrival time with the acquired signal indicative of variation in pulse arrival time.

5. The controller as claimed in claim 4 , wherein the different sample functions of arterial compliance are generated by taking the derivative of each sample function of arterial volume with respect to arterial transmural pressure.

6. The controller as claimed in claim 4 , wherein the further model fitting procedure comprises:
deriving a signal indicative of arterial compliance by differentiating the derived V a-osc signal with respect to transmural pressure;
generating a modeled pulse arrival time function, ΔPAT osc , by substituting the derived V a-osc signal and the derived signal indicative of arterial compliance into the pulse arrival time model; and
comparing each of the generated modeled pulse arrival time functions of claim 4 with the modeled pulse arrival time function ΔPAT osc .

7. The controller as claimed in claim 1 , wherein the pulse arrival time model has the form:

Δ
⁢

PAT
⁡
(

P
tm

)

=

(

1

PWV
⁡
(

P
tm

)

-

1

PWV
ref

)

·
L

where

PWV
⁡
(

P
tm

)

=

V
⁡
(

P
tm

)

ρ
⁢

C
⁡
(

P
tm

)

where PWV(P tm ) is pulse wave velocity as a function of transmural pressure, ΔPAT is variation in pulse arrival time, V(P tm ) is arterial volume as function of transmural pressure, C(P tm ) is arterial compliance as function of transmural pressure, ρ is blood density, L is the length of a body-contacting portion of the oscillometry measurement device, and PWV ref is the pulse wave velocity at P tm =MAP, where MAP is mean arterial pressure.

8. The controller as claimed in claim 1 , wherein the controller is further operably couplable in use with an ECG sensor device and a PPG sensor.

9. The controller as claimed in claim 1 , wherein the acquiring the signal indicative of arterial volume variation comprises:
controlling an inflatable cuff of the oscillometric measurement device to gradually inflate to thereby vary said applied pressure to the artery beneath the cuff through said range of applied pressures.

10. The controller as claimed in claim 1 , wherein the first model fitting procedure comprises:
generating different sample functions of arterial volume as a function of transmural pressure using the arterial volume model;
extracting from each sample function a corresponding sample signal representative of variation in peak-to-peak amplitude of arterial volume across said range of applied pressures; and
comparing each sample peak-to-peak volume amplitude signal with the extracted volume amplitude signal of claim 1 .

11. The controller as claimed in claim 1 , wherein the pre-determined arterial volume model is based on a relation having the form

V
⁡
(

P
tm

)

=

d
·
L
·

ln
⁡
(

a
⋆

P
tm

+

Assignees

• Koninklijke Philips Nv

Inventors

• Bogatu Laura Ioana
• Muehlsteff Jens
• Kuenen Maarten Petrus Joseph
• Bresch Erik

Classifications

• A61B5/02416

  using photoplethysmograph signals, e.g. generated by infrared radiation (A61B5/14552 takes precedence) · CPC title

• A61B5/0225

  the pressure being controlled by electric signals, e.g. derived from Korotkoff sounds · CPC title

• A61B5/02225

  using the oscillometric method · CPC title

• A61B5/02125

  of pulse wave propagation time · CPC title

• A61B5/318

  Heart-related electrical modalities, e.g. electrocardiography [ECG] · CPC title