KR20220060769A - Apparatus and method for estimating blood pressure by using cardiac output - Google Patents

Abstract

According to one embodiment of the present invention, a method and apparatus for estimating blood pressure can estimate and calculate blood pressure using another bio-signal without direct blood pressure measurement by measuring a plurality of bio-signals from a user, calculating cardiac output from the measured bio-signals, and using the calculated cardiac output and weight, height, body fat, heart rate, and cardiac output signals among the plurality of bio-signals to estimate and provide blood pressure.

Description

Apparatus and method for estimating blood pressure through cardiac output

The present invention relates to an estimating apparatus and method for estimating blood pressure, and more particularly, to an estimating apparatus and method for estimating blood pressure using cardiac output.

Cardiac output is the amount of blood per minute that goes to the whole body through the heartbeat, and is an indicator that reflects not only the heart function but also the state of the entire circulatory system, and is controlled through the autonomous regulation of systemic tissues.

Recently, as the paradigm of medical service has changed from treatment/hospital-centered to prevention/consumer-centered, the trend of ‘self-health measurement’, in which one’s own health status is recorded and managed, is spreading.

As a health monitoring of cardiovascular disease, blood vessel and blood pressure measurement are known through many studies as risk assessment factors. However, although cardiac output is an important factor among health indicators, there is no solution to non-invasively measure it outside of a hospital. As a self-health measurement solution, there are body composition analyzers used in various places such as exercise, health, and hospitals, but this is a situation where only the external balance is measured with the physical measurement of the human body. Cardio-cerebrovascular disease ranks first in Korea's top 10 fatal diseases, and actual health requires evaluating signals inside the body. The non-invasive measurement method attaches electrodes to the outside of the human body to measure the necessary bio-signals, and since this measurement method is simple and easy to use, it can be used at a health check-up center or at home. Therefore, the non-invasive measurement method can be easily measured like a scale in everyday life, not in a hospital.

As a method of measuring cardiac output from a long time ago, a method of measuring the amount of blood actually ejected into the heart through an invasive method using a catheter has been used. As a result, studies on methods or devices for measuring cardiac output that can significantly represent cardiac output signals have been actively conducted. This gradually increased.

In addition, in many studies of estimating blood pressure using cardiac output in the prior art, there was a need to calculate or estimate vascular resistance, but there is a problem in that it is difficult to measure the vascular resistance. there was

Republic of Korea Patent Publication No. 10-2014-0058570 (published on May 14, 2014)

Stroke volume equation for impedance cardiography, Medical & Biological Engineering & Computing 2005, Vol. 43

An object of the present invention is to provide an apparatus and method for estimating a blood pressure capable of calculating a cardiac output from a plurality of biosignals obtained from a user, and using the method to estimate and calculate a user's blood pressure without a separate blood pressure measuring tool. aim to

In addition, in the case of blood pressure measured with a general home blood pressure monitor, the present invention has an effect of easily solving the problem that it is difficult to actively respond to an abnormal signal because only the value at the time of measurement is displayed in a single shot.

Another object of the present invention is to provide an apparatus and method that are provided in fitness centers, public health centers, and public places so that an individual user can easily estimate cardiac output and blood pressure without going to a hospital.

A blood pressure estimating apparatus according to an embodiment of the present invention includes: a sensor unit for measuring a plurality of bio-signals from a user; and a processor for calculating a cardiac output from the bio-signals and estimating blood pressure by using the calculated cardiac output and some of the plurality of bio-signals.

In addition, in the blood pressure estimation apparatus according to an embodiment of the present invention, the user's bio-signals include weight, height, body fat mass, heart rate, and bio-resistance signals.

In addition, in the blood pressure estimating apparatus according to an embodiment of the present invention, the processor includes, among the biosignals, weight, height, body fat mass and left ventricle opening time, the local maximum value of the collected biometric differential signal, the DC component value of the bioresistance signal, and It is characterized in that the cardiac output is calculated by including a plurality of cardiac output calibration constants.

In addition, in the blood pressure estimating apparatus according to an embodiment of the present invention, the processor estimates the blood pressure including the calculated cardiac output, heart rate per minute, and a plurality of blood pressure correction constants.

In addition, a method for estimating blood pressure according to an embodiment of the present invention includes measuring a plurality of bio-signals from a user; calculating a cardiac output from the biosignal; and estimating blood pressure by using the calculated cardiac output and some of the plurality of biosignals.

In addition, in the method for estimating blood pressure according to an embodiment of the present invention, the user's bio-signals include weight, height, body fat mass, heart rate, and bio-storage signals.

In addition, in the blood pressure estimation method according to an embodiment of the present invention, the step of calculating cardiac output includes, among the biosignals, weight, height, body fat mass and left ventricle opening time, the local maximum value of the bioresistance differential signal, and the DC of the bioresistance signal. It is calculated including component values and a plurality of cardiac output correction constants.

In addition, in the blood pressure estimation method according to an embodiment of the present invention, the step of estimating the blood pressure is characterized in that the calculation includes cardiac output, heart rate, and a plurality of blood pressure correction constants.

The blood pressure estimating apparatus and method of the present invention have the advantage of calculating and estimating blood pressure using cardiac output among various biosignals of the user without a separate blood pressure measuring tool.

In addition, the present invention has the advantage of being able to calculate the user's cardiac output using only relatively easy to obtain weight, height, body fat mass, heart rate per minute, and bioresistance signals among various biosignals, and estimate blood pressure using these signals.

In addition, the present invention has an advantage in that it is possible to provide a method for estimating blood pressure that is robust against distortion such as cuff hypertension by estimating blood pressure based on a user's cardiac output.

In addition, the present invention has an advantage in that it is possible to continuously calculate and monitor blood pressure in a daily environment without a separate blood pressure measuring device, so that the user can be informed of risks such as high blood pressure in real time.

1 is a block diagram illustrating an overall configuration of an apparatus for estimating blood pressure according to an embodiment of the present invention.
2 is a flowchart of a blood pressure estimation method according to an embodiment of the present invention.
3 is a diagram for explaining an impedance signal and a left ventricle open time in a signal measured using the blood pressure estimation apparatus of the present invention.

Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings. However, the spirit of the present invention is not limited to the presented embodiments, and those skilled in the art who understand the spirit of the present invention may add, change, delete, etc. other components within the scope of the same spirit, through addition, change, deletion, etc. Other embodiments included within the scope of the invention may be easily proposed, but this will also be included within the scope of the invention. In addition, components having the same function within the scope of the same idea shown in the drawings of each embodiment will be described using the same reference numerals.

1 is a block diagram illustrating an overall configuration of an apparatus for estimating blood pressure according to an embodiment of the present invention.

The blood pressure estimating device 10000 is a device capable of estimating blood pressure by securing the user's bio signals in the human body P, and includes a processor 1200 for calculating cardiac output or estimating blood pressure, which will be described later; The sensor unit 1100 for acquiring the user's bio-signals, the output unit 1300 for outputting cardiac output and blood pressure calculated to the user, and various data and calculation results used in the blood pressure estimating device 10000 It includes a storage unit 1400 that can store, a user input unit 1500 that can receive various information (eg, height, weight) from a user, and a communication unit 1600 that operates to transmit and receive data with the outside. is composed by

The sensor unit 1100 includes a plurality of electrodes that can be in contact with the user or a part of the human body (P),

The processor 1200 introduces a current to the measurement site in contact with the plurality of electrodes of the sensor unit 1100 and measures the change in the blood flow of the heart over time in the electrical collection signal, so that the left ventricular opening time (LVET) Ejection time, left ventricle ejection time) can be obtained, and cardiac output can be measured using a change in the user's bio-resistance signal (eg, impedance) according to the change in blood flow, and the impedance included in the collected signal. It is characterized in that the cardiac output is calculated using the signal.

That is, the above-described bioresistance signal may be an impedance signal as described above, and in other cases may be a reactance signal.

As shown in FIG. 3 , when the x-axis is time and the y-axis is impedance, the maximum value of the bioresistance signal, i.e., within the left ventricle opening time (LVET) and the left ventricle opening time to be described later, from the amount of change in the impedance. It is possible to obtain a local maximum value within the LVET unit time of the resistance differential signal.

In addition, the sensor unit 1100 is in the form of a pressure sensor capable of sensing a user's weight, or other types of sensors capable of obtaining body fat mass or heart rate, in addition to the electrical collection signals as described above, are added or configured in a complex manner. it might be

In addition, the sensor unit 1100 may be provided in the form of a user's direct input through the communication unit 1600 or the user input unit 1500 interlocked with the sensor unit 1100, such as the height of the user.

In addition, the processor 1200 serves to estimate blood pressure as a result by using a single or a plurality of bio-signals measured by the sensor unit 1100 .

The blood pressure estimating device 10000 is manufactured in the form of a scale using both feet as a measuring site for diversity of measurement sites, a handheld type in which both hands are held as a measuring site, or both hands or upper body as a measuring site. It can also be manufactured in the form of tongs, etc.

Illustratively, in the form of a scale system that estimates blood pressure using both feet, a current flows through one foot and the time it arrives at the other foot is measured, and cardiac output can be calculated using that time. In the handheld type that measures the stroke volume, the cardiac output can be measured using an electrical change by passing an electric current in both hands.

The processor 1200 may calculate a user's cardiac output by utilizing a plurality of user biometric information input through the sensor unit 1100 and the user input unit 1500 .

Specifically, the user's bio-signals include weight (BW), height (H), body fat mass (BMF), heart rate per minute (HR), impedance signal (Z), which is one of bioresistance signals, and left ventricle opening time (LVET). may include

As a result, the processor 1200 may estimate the cardiac output (SV) as shown in [Equation 1] below by using various user bio-signals obtained through the sensor unit 1100 .

는 임피던스 신호 중 직류성분의 값인 DC성분값(Direct Current), (dZ/dt)max는 임피던스 미분 신호의 LVET 단위 시간 내에서의 로컬 최대값, LVET는 좌심실 개방시간이다. LVET는 일반적으로, 대동맥 판막 개방지점과 대동맥 판막 폐쇄지점 사이의 시간으로 해석된다.where SV is stroke volume, a, b, c, d, e, and f are all cardiac output correction constants, BW is body weight, H is height or height, BFM is body fat mass, Z is impedance signal,

is the value of the DC component of the impedance signal (Direct Current), (dZ/dt)max is the local maximum value within the LVET unit time of the impedance differential signal, and LVET is the left ventricle opening time. LVET is generally interpreted as the time between the opening of the aortic valve and the closing of the aortic valve.

As described above, LVET and (dZ/dt)max values can be calculated by observing the time-series-measured change amount of the impedance signal as shown in FIG. 3 .

The processor 1200 calculates the cardiac output (SV) by using Equation 1 above, and then uses the heart rate per minute (HR) among the calculated cardiac output (SV) and the additional user's biosignals, As a result, the blood pressure can be estimated using the following [Equation 2].

In addition, more preferably, in one embodiment, when calculating the cardiac output correction constants a, b, c, d, e, f as 0.005, 6.995, -3.502, -0.876, 0.569, 43.282, respectively, It was confirmed that the correlation between the results measured in medical echocardiography and the cardiac output measurement results, r ² =0.719.

Here, BP is the estimated blood pressure, SV is cardiac output, HR is heart rate per minute, and g, h, i, and j are all blood pressure correction constants.

The cardiac output correction constant (a, b, c, d, e, f) and the blood pressure correction constant (g, h, i, j) are calculated by the processor 1200 to calculate the cardiac output or the blood pressure. When used, it can be stored in the storage unit 1400 .

In addition, when fine adjustment of the cardiac output calibration constant and the blood pressure calibration constant is required, the changed calibration constants are received from the outside (eg, a remote server) through the communication unit 1600, and the processor 1200 is The values of the calibration constants stored in the storage unit 1400 may be updated.

Through such an update, as a result, the accuracy of the calculation (estimation) of the cardiac output or the blood pressure may be increased.

2 is a flowchart of a blood pressure estimation method according to an embodiment of the present invention.

First, the blood pressure estimating apparatus generates a constant current source by the processor 1200 and measures a plurality of user bio-signals through the sensor unit 1100 ( S100 ).

More specifically, when a plurality of electrodes that can be in contact with a part of the human body P (upper body, both feet, or both hands) are attached, a constant current is introduced into the human body P, and the electrical collection signal measured in the human body P is amplified After that, the carrier frequency is separated and removed from the amplified collection signal, and an impedance signal is obtained by demodulating the collection signal.

In order to improve the signal-to-noise ratio (SNR) of the demodulated acquisition signal, AC and DC are separated from the resistance component and the reactance component of the acquisition signal and amplified, and each separated resistive component signal is transmitted to a converter to provide a digital signal convert it to use

The processor 1200 calculates a cardiac output from the biosignal ( S200 ).

More specifically, the processor 1200 obtains the left ventricle open time, the local maximum value of the impedance differential signal that is the bioresistance signal, the DC component value of the impedance signal, etc. by using the impedance analysis method for the collected signal converted into the digital signal. And, through the functions of the other sensor unit 1100, weight, height, body fat mass, heart rate, etc. may be acquired, and as a result, cardiac output (SV) may be calculated using Equation 1 above.

Thereafter, the processor 1200 estimates the blood pressure using the calculated cardiac output and the plurality of biosignals (S300).

More specifically, the processor 1200 may estimate the blood pressure BP using Equation 2 above using the calculated cardiac output SV and heart rate per minute HR.

In addition, the processor 1200 outputs the estimated blood pressure to the user through the output unit 1300 (S400). More specifically, the output unit 1300 may include a display, or may transmit the estimated blood pressure to the outside through the communication unit 1600 and output it to the user.

Meanwhile, the present embodiments can be implemented as computer-readable codes on a computer-readable recording medium. The computer-readable recording medium includes all types of recording devices in which data readable by a computer system is stored.

Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage device, etc. include In addition, the computer-readable recording medium is distributed in a computer system connected to a network, so that the computer-readable code can be stored and executed in a distributed manner. In addition, functional programs, codes, and code segments for implementing the present embodiments can be easily inferred by programmers in the technical field to which the present invention pertains.

In addition, the above-described processor 1200 may exist at a location remote from the sensor unit 1100 . That is, the processor 1200 may be implemented in a remote server, etc. to calculate cardiac output and blood pressure based on the biometric information received from the sensor unit 1100 and the communication unit 1600 .

Those of ordinary skill in the art to which the present disclosure pertains will be able to understand that the disclosure may be implemented in other specific forms without changing the technical spirit or essential features. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive.

10000: blood pressure estimating device
1100: sensor unit
1200: processor
1300: output unit
1400: storage
1500: user input unit
1600: communication department

Claims (8)

measuring a plurality of biosignals from a user;
calculating a cardiac output from the biosignal;
and estimating blood pressure by using the calculated cardiac output and some of the plurality of biosignals. According to claim 1,
The user's bio-signals include weight, height, body fat mass, heart rate, and bio-storage signals. 3. The method of claim 2,
Calculating the cardiac output includes, among the biosignals, weight, height, body fat mass and left ventricle opening time, the local maximum value of the collected bioresistance differential signal, the DC component value of the bioresistance signal, and a plurality of cardiac output correction constants. A blood pressure estimation method, characterized in that calculated by 4. The method of claim 3
The step of estimating the blood pressure is calculated by including cardiac output, heart rate per minute, and a plurality of blood pressure correction constants. a sensor unit for measuring a plurality of biosignals from a user; and
and a processor for calculating a cardiac output from the bio-signals and estimating blood pressure by using the calculated cardiac output and some of the plurality of bio-signals. 6. The method of claim 5,
The user's bio-signals include weight, height, body fat mass, heart rate, and bio-resistance signals. 7. The method of claim 6,
the processor
Calculating the cardiac output including the body weight, height, body fat mass and left ventricular opening time, the local maximum value of the collected bioresistance differential signal, the DC component value of the bioresistance signal, and a plurality of cardiac output correction constants among the biosignals Blood pressure estimating device, characterized in that. 8. The method of claim 7
the processor is
and estimating the blood pressure including the calculated cardiac output, heart rate, and a plurality of blood pressure correction constants.

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