Apparatus and method for determining a blood pressure of a subject

Patent metadata

Field	Value
Publication number	US-10925495-B2
Application number	US-201715766987-A
Country	US
Kind code	B2
Filing date	May 4, 2017
Priority date	May 4, 2017
Publication date	Feb 23, 2021
Grant date	Feb 23, 2021

Abstract

The present application discloses an apparatus for determining a blood pressure of a subject. The apparatus includes one or more sensors configured to measure a first physiological parameter of the subject; a memory; and one or more processors. The memory stores computer-executable instructions for controlling the one or more processors to decompose a first physiological signal corresponding to the first physiological parameter using an empirical mode decomposition algorithm into a sum of a plurality of intrinsic mode functions and a residual; identify one or more first intrinsic mode functions of the plurality of intrinsic mode functions that are associated with a noise signal, thereby obtaining one or more second intrinsic mode functions of the plurality of intrinsic mode functions that are different from the one or more first intrinsic mode functions; and calculate a denoised physiological signal by accumulating the one or more second intrinsic mode functions.

First claim

What is claimed is:

1. An apparatus for determining a blood pressure of a subject, comprising:
one or more sensors configured to measure a first physiological parameter of the subject;
a memory; and
one or more processors;
wherein the one or more sensors, the memory and the one or more processors are coupled to each other;
the memory stores computer-executable instructions for controlling the one or more processors to:
decompose a first physiological signal corresponding to the first physiological parameter using an empirical mode decomposition algorithm into a sum of a plurality of intrinsic mode functions and a residual, wherein the first physiological parameter is a pulse wave; and the first physiological signal is a photoplethysmogram signal;
identify one or more first intrinsic mode functions of the plurality of intrinsic mode functions that are associated with a noise signal, thereby obtaining one or more second intrinsic mode functions of the plurality of intrinsic mode functions that are different from the one or more first intrinsic mode functions;
calculate a denoised physiological signal by accumulating the one or more second intrinsic mode functions;
calculate a ratio of a photoplethysmogram peak intensity to a photoplethysmogram valley intensity in one cardiac cycle;
determine a photoplethysmogram intensity ratio based on the ratio of the photoplethysmogram peak intensity to the photoplethysmogram valley intensity in the one cardiac cycle;
obtain a first electrocardiography R-wave signal;
determine a time interval between an electrocardiography R-wave peak of the first electrocardiography R-wave signal and a peak of a first derivative of the denoised physiological signal in one cardiac cycle;
determine a pulse transit time based on the time interval; and
determine the blood pressure of the subject using a blood pressure calculation algorithm based on the pulse transit time and the photoplethysmogram intensity ratio, according to equations (1) and (2):

DBP
-

a
PIR

+

b
⁢

m

h
2

+
c

;
and

(
1
)

SBP
=

a
PIR

+

b
⁢

m

h
2

+

d

PTT
2

+
e

;

(
2
)

wherein DBP is a diastolic blood pressure of the subject, SBP is a systolic blood pressure of the subject, PTT is the pulse transit time, PIR is the photoplethysmogram intensity ratio, m is a body weight of the subject, h is a height of the subject, and a, b, c, d, and e are constant coefficients.

2. The apparatus of claim 1 , wherein each of the plurality of intrinsic mode functions has a characteristic frequency, values of characteristic frequencies of the plurality of intrinsic mode functions are different from each other.

3. The apparatus of claim 2 , wherein the memory stores computer-executable instructions for controlling the one or more processors to select one or more of the plurality of intrinsic mode functions having characteristic frequencies outside a range of acceptable characteristic frequencies as the one or more first intrinsic mode functions.

4. The apparatus of claim 3 , wherein the one or more first intrinsic mode functions are associated with low frequency baseline drifting.

5. The apparatus of claim 1 , wherein the memory stores computer-executable instructions for controlling the one or more processors to:
prior to decompose a first physiological signal, filter a high frequency noise from a second physiological signal to obtain the first physiological signal.

6. The apparatus of claim 1 , wherein the one or more sensors are configured to detect an electrocardiography R-wave of the subject to acquire a second electrocardiography R-wave signal;
the memory stores computer-executable instructions for controlling the one or more processors to filter a high frequency noise from a second electrocardiography R-wave signal thereby obtaining the first electrocardiography R-wave signal.

7. The apparatus of claim 1 , wherein the first physiological signal is decomposed into a function according to equation (3):

s
⁡

(
t
)

=

∑

k
=
1

N

⁢

IMF
k

⁡

(
t
)

+

r
N

⁡

(
t
)

;

(
3
)

Assignees

• Boe Technology Group Co Ltd

Inventors

• Chen Xue
• Wang Guohe

Classifications

• A61B5/352

  Detecting R peaks, e.g. for synchronising diagnostic apparatus; Estimating R-R interval · CPC title

• A61B5/02416

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

• A61B5/7221

  Determining signal validity, reliability or quality (preventing, reducing or removing noise induced by motion artefacts A61B5/7207; noise originating from a therapeutic or surgical apparatus A61B5/7217) · CPC title

• A61B5/02116

  of pulse wave amplitude (A61B5/02225 takes precedence) · CPC title

• A61B5/7278

  Artificial waveform generation or derivation, e.g. synthesizing signals from measured signals · CPC title