Method and apparatus for obtaining relevant characteristic parameters and indexes of tonoarteriogram (TAG) signals
The present invention provides a method and an apparatus for obtaining relevant characteristic parameters and indexes of tonoarteriogram (TAG) signals, relating to the technical field of blood pressure monitoring. A signal acquisition module acquires TAG signals from a target subject; a signal processing module obtains relevant characteristic parameters and indexes of continuous blood pressure from obtained TAG signals of target subject by calculating and processing through a predetermined mathematical model and a statistical algorithm, wherein the relevant characteristic parameters and indexes of continuous blood pressure include at least one of root mean square value of continuous blood pressure (RMSBP) and standard deviation of continuous blood pressure (SDBP), an evaluation module evaluates the status of continuous blood pressure based on characteristic parameters and indexes obtained from the target subject, an alarm module initiates an alarm when the relevant characteristic parameters and indexes of continuous blood pressure monitored to be abnormal, which allows to monitor the blood pressure of the target user at different period of time, realizing rapid blood pressure measurement, and enabling timely alarms to ensure the safety of the target user.
1 . An apparatus for detecting abnormality in blood pressure of a target subject for diagnosis of acute cardiovascular disease, the apparatus comprises:
a signal acquisition module comprises at least a continuous blood pressure sensor adapted to operate in a normal mode and a power saving mode, wherein the signal acquisition module detects tonoarteriogram (TAG) signals from a target subject in the normal mode, and detects information on rhythm and amplitude of heartbeat of the target subject in the power saving mode;
wherein, when a change in the rhythm and amplitude of the heartbeat of the target subject is detected to exceed a predetermined threshold when operated in the power saving mode, the signal acquisition module is adapted to automatically turn to operate in the normal mode to detect the TAG signals of the target;
a signal processing module adapted to process the detected TAG signals and the detected rhythm and amplitude of the heartbeat of the target subject for determining relevant characteristic parameters and indexes of the TAG signals from the target subject;
wherein, when operated in the normal mode, the signal processing module is configured to process the TAG signals based on a statistical calculation; and
wherein, when operated in the power saving mode, the signal processing module is configured to process the rhythm and amplitude of the heartbeat based on estimation from a mathematical model;
wherein the relevant characteristic parameters and indexes of the TAG signals comprise at least one of root mean square value of continuous blood pressure (RMSBP) and standard deviation of continuous blood pressure (SDBP);
wherein, when operated in the normal mode, the RMSBP is determined based on the statistical calculation using the detected TAG signals:
RMSBP
=
rmsv
[
tag
(
t
)
]
=
1
N
∑
i
=
1
N
x
i
2
where x i is a continuous blood pressure value, N is a number of data points, rmsv is a root mean square value, and tag is a continuous blood pressure signal;
wherein, when operated in the power saving mode, the RMSBP is determined based on the estimation from the mathematical model using the detected information on the rhythm and amplitude of the heartbeat:
RMSBP
=
a
¯
2
λ
h
+
d
2
where ā is an average pulse pressure within a predetermined monitoring period, λ is an average heart rate within the predetermined monitoring period, λ=E[1/(T i+1 −T i )], T i T i+1 are random variables to indicate onset of blood pressure waveform per beat within the predetermined monitoring period, h is an average strength of the blood pressure waveform within the predetermined monitoring period,
h
=
∫
-
∞
∞
h
t
a
g
2
(
t
)
dt
,
h
t
a
g
(
t
)
is a continuous blood pressure waveform with a mean amplitude of 0 within one cardiac cycle, t indicates time, d is a predetermined constant represents for DC component of the blood pressure waveform, and E indicates a mean value of [1/(T i+1 −T i )];
wherein, when operated in the normal mode, the SDBP is determined based on the statistical calculation using the detected TAG signals:
SDBP
=
std
[
tag
(
t
)
]
=
1
N
-
1
∑
i
=
1
N
❘
"\[LeftBracketingBar]"
x
i
-
μ
❘
"\[RightBracketingBar]"
2
where x i is a continuous blood pressure value, N is a number of data points, μ is a mean of the continuous blood pressure value, and std is standard deviation, tag is a continuous blood pressure signal;
wherein, when operated in the power saving mode, the SDBP is determined based on the estimation from the mathematical model using the detected information on the rhythm and amplitude of the heartbeat:
SDBP
=
a
_
λ
h
where ā is the average pulse pressure within a predetermined monitoring period, λ is an average heart rate within predetermined monitoring period, λ=E[1/(T i+1 −T i )], T i T i+1 are random variables to indicate the onset of blood pressure waveform per beat within the predetermined monitoring period, h is an average strength of the blood pressure waveform within the predetermined monitoring period
h
=
∫
-
∞
∞
h
tag
2
(
t
)
dt
,
h
tag
(
t
)
is a continuous blood pressure waveform with a mean amplitude of 0 within one cardiac cycle, t indicates time and E indicates the mean value of [1/(T i+1 −T i )];
an evaluation module for evaluating a status of a continuous blood pressure of the target subject based on the characteristic parameters and indexes obtained from the target subject; wherein the evaluation module is configured to determine a continuous blood pressure level based on the RMSBP, and to determine a continuous blood pressure variability based on the SDBP; and
an alarm module for initiating an alarm when the relevant characteristic parameters and indexes of the TAG signals monitored are abnormal.
2 . The apparatus according to claim 1 , wherein the continuous blood pressure sensor comprises one or more of a multi-wavelength photoplethysmogram (PPG) sensor, a single-wavelength PPG sensor, an electrocardiogram (ECG) sensor, and a pressure sensor.
3 . The apparatus according to claim 1 , wherein based on the determined continuous blood pressure level, the evaluation module characterizes the overall blood pressure level of the target subject.
4 . The apparatus according to claim 1 , wherein based on the determined continuous blood pressure variability, the evaluation module characterizes the continuous blood pressure variability of the target subject.
5 . The apparatus according to claim 1 , wherein based on the obtained relevant characteristic parameters and indexes of TAG signals, the signal processing module characterizes any one of heart rate, pulse pressure, blood pressure waveform and vascular compliance of the target subject.
6 . The apparatus according to claim 1 , wherein based on the obtained relevant characteristic parameters and indexes of TAG signals, the signal processing module classifies the target subject, the classification of the target subject includes a hypertensive category.
7 . The apparatus according to claim 1 , wherein the alarm module has the forms of one or more of local alarm to call for help, sending an alarm message to an emergency contact of the target user and sending an alarm message to an emergency centre.
8 . The apparatus according to claim 1 , wherein the apparatus is implemented in a wearable, unobtrusive continuous blood pressure measurement device, forms of the device include one or more of a cell phone, a watch, a bracelet, a ring, a wristband, and a vest.
9 . A method for detecting abnormality in blood pressure of a target subject for diagnosis of acute cardiovascular disease using the apparatus of claim 1 , the method comprises:
via at least the continuous blood pressure sensor of the signal acquisition module, acquiring, tonoarteriogram (TAG) signals from the target subject when the signal acquisition module is operated in the normal mode, and acquiring the information on rhythm and amplitude of heartbeat of the target subject when the signal acquisition module is operated in the power saving mode;
wherein, when the change in the rhythm and amplitude of the heartbeat of the target subject is detected to exceed the predetermined threshold, switching from the power saving mode automatically to the normal mode to acquire the TAG signals of the target subject;
processing, via the signal processing module, the acquired TAG signals and the acquired rhythm and amplitude of the heartbeat of the target subject to determine relevant characteristic parameters and indexes of the TAG signals from the target subject;
wherein, when operated in the normal mode, the signal processing module is configured to process the TAG signals based on the statistical calculation; and
wherein, when operated in the power saving mode, the signal processing module is configured to process the rhythm and amplitude of the heartbeat based on estimation from the mathematical model;
wherein the relevant characteristic parameters and indexes of the TAG signals comprise at least one of the RMSBP and the SDBP;
wherein, when operated in the normal mode, determining the RMSBP based on the statistical calculation using the acquired TAG signals:
RMSBP
=
rmsv
[
tag
(
t
)
]
=
1
N
∑
i
=
1
N
x
i
2
where x i is the continuous blood pressure value, N is the number of data points, rmsv is the root mean square value, and tag is the continuous blood pressure signal;
wherein, when operated in the power saving mode, determining the RMSBP based on the estimation from the mathematical model using the acquired information on the rhythm and amplitude of the heartbeat:
RMSBP
=
a
_
2
λ
h
+
d
2
where ā is the average pulse pressure within the predetermined monitoring period, λ is the average heart rate within the predetermined monitoring period λ=E[1/(T i+1 −T i )], T i T i+1 are random variables to indicate the onset of blood pressure waveform per beat within the predetermined monitoring period, h is the average strength of the blood pressure waveform within predetermined monitoring period
h
=
∫
-
∞
∞
h
tag
2
(
t
)
dt
,
h
tag
(
t
)
is the continuous blood pressure waveform with the mean amplitude of 0 within one cardiac cycle, t indicates time, d is the predetermined constant represents for DC component of the blood pressure waveform, and E indicates the mean value of [1/(T i+1 −T i )];
wherein, when operated in the normal mode, the SDBP is determined based on the statistical calculation using the acquired TAG signals:
SDBP
=
std
[
tag
(
t
)
]
=
1
N
-
1
∑
i
=
1
N
❘
"\[LeftBracketingBar]"
x
i
-
μ
❘
"\[RightBracketingBar]"
2
where x i is the continuous blood pressure value, N is the number of data points, μ is the mean of continuous blood pressure value, and std is the standard deviation, tag is the continuous blood pressure signal;
wherein, when operated in the power saving mode, the SDBP is determined based on the estimation from the mathematical model using the detected information on the rhythm and amplitude of the heartbeat:
SDBP
=
a
_
λ
h
where ā is the average pulse pressure within the predetermined monitoring period, λ is the average heart rate within predetermined monitoring period λ=E[1/(T i+1 −T i )], T i T i+1 are random variables to indicate the onset of blood pressure waveform per beat within the predetermined monitoring period, h is the average strength of the blood pressure waveform within the predetermined monitoring period
h
=
∫
-
∞
∞
h
tag
2
(
t
)
dt
,
h
tag
(
t
)
is the continuous blood pressure waveform with the mean amplitude of 0 within one cardiac cycle, t indicates time and E indicates the mean value of [1/(T i+1 −T i )];
evaluating, via the evaluation module, the status of the continuous blood pressure of the target subject based on the characteristic parameters and indexes obtained from the target subject; wherein the evaluation module is configured to determine the continuous blood pressure level based on the RMSBP, and to determine the continuous blood pressure variability based on the SDBP; and
initiating, via the alarm module, the alarm when the relevant characteristic parameters and indexes of the TAG signals monitored are abnormal.
10 . The method according to claim 9 , wherein the evaluating step comprises characterizing the overall blood pressure level of the target subject based on assessing the continuous blood pressure level and/or characterizing the continuous blood pressure variability of the target subject based on the assessed continuous blood pressure variability.
11 . An electronic device for detecting abnormality in blood pressure of a target subject for diagnosis of acute cardiovascular disease, comprising:
a signal acquisition module comprises at least a continuous blood pressure sensor adapted to operate in a normal mode and a power saving mode, wherein the signal acquisition module detects tonoarteriogram (TAG) signals from a target subject in the normal mode, and detects information on rhythm and amplitude of heartbeat of the target subject in the power saving mode;
wherein, when a change in the rhythm and amplitude of the heartbeat of the target subject is detected to exceed a predetermined threshold when operated in the power saving mode, the signal acquisition module is adapted to automatically turn to operate in the normal mode to acquire the TAG signals of the target;
a signal processing module adapted to process the detected TAG signals and the detected rhythm and amplitude of the heartbeat of the target subject for obtaining relevant characteristic parameters and indexes of the TAG signals from the target subject;
wherein, when operated in the normal mode, the signal processing module is configured to process the TAG signals based on a statistical calculation; and
wherein, when operated in the power saving mode, the signal processing module is configured to process the rhythm and amplitude of the heartbeat based on estimation from a mathematical model;
wherein the relevant characteristic parameters and indexes of the TAG signals comprise at least one of root mean square value of continuous blood pressure (RMSBP) and standard deviation of continuous blood pressure (SDBP);
wherein, when operated in the normal mode, the RMSBP is determined based on the statistical calculation using the detected TAG signals:
RMSBP
=
rmsv
[
tag
(
t
)
]
=
1
N
∑
i
=
1
N
x
i
2
where x i is a continuous blood pressure value, N is a number of data points, rmsv is a root mean square value, and tag is a continuous blood pressure signal;
wherein, when operated in the power saving mode, the RMSBP is determined based on the estimation from the mathematical model using the detected information on the rhythm and amplitude of the heartbeat:
RMSBP
=
a
_
2
λ
h
+
d
2
where ā is an average pulse pressure within a predetermined monitoring period, λ is an average heart rate within the predetermined monitoring period, λ=E[1/(T i+1 −T i )], T i T i+1 are random variables to indicate onset of blood pressure waveform per beat within the predetermined monitoring period, h is an average strength of the blood pressure waveform within the predetermined monitoring period,
h
=
∫
-
∞
∞
h
tag
2
(
t
)
dt
,
h
tag
(
t
)
is a continuous blood pressure waveform with a mean amplitude of 0 within one cardiac cycle, t indicates time, d is a predetermined constant represents for DC component of the blood pressure waveform, and E indicates a mean value of [1/(T i+1 −T i )];
wherein, when operated in the normal mode, the SDBP is determined based on the statistical calculation using the detected TAG signals:
SDBP
=
std
[
tag
(
t
)
]
=
1
N
-
1
∑
i
=
1
N
❘
"\[LeftBracketingBar]"
x
i
-
μ
❘
"\[RightBracketingBar]"
2
where x i is a continuous blood pressure value, N is a number of data points, μ is a mean of the continuous blood pressure value, and std is standard deviation, tag is a continuous blood pressure signal;
wherein, when operated in the power saving mode, the SDBP us determined based on the estimation from the mathematical model using the detected information on the rhythm and amplitude of the heartbeat:
SDBP
=
a
_
λ
h
where ā is the average pulse pressure within a predetermined monitoring period, λ is an average heart rate within predetermined monitoring period, λ=E[1/(T i+1 −T i )], T i T i+1 are random variables to indicate the onset of blood pressure waveform per beat within the predetermined monitoring period, h is an average strength of the blood pressure waveform within the predetermined monitoring period
h
=
∫
-
∞
∞
h
tag
2
(
t
)
dt
,
h
tag
(
t
)
is a continuous blood pressure waveform with a mean amplitude of 0 within one cardiac cycle, t indicates time and E indicates the mean value of [1/(T i+1 −T i )];
an evaluation module for evaluating a status of a continuous blood pressure of the target subject based on the characteristic parameters and indexes obtained from the target subject; wherein the evaluation module is configured to determine a continuous blood pressure level based on the RMSBP, and to determine a continuous blood pressure variability based on the SDBP; and
an alarm module for initiating an alarm when the relevant characteristic parameters and indexes of the TAG signals monitored are abnormal.