KR20240039650A - Blood pressure estimation method and device using wearable device - Google Patents

Abstract

The present invention is a blood pressure estimation method and blood pressure estimation device using a wearable device, which measures a photoplethysmographic pulse wave (PPG) signal through a wearable device worn by a subject, and determines the correlation between the contraction and relaxation movements of the heart and the photoplethysmographic pulse wave signal. A technology for estimating a subject's blood pressure based on the following characteristics is disclosed.

Description

Blood pressure estimation method and device using wearable device}

The present invention is a blood pressure estimation method and blood pressure estimation device using a wearable device. More specifically, the present invention measures a photoplethysmographic pulse wave (PPG) signal through a wearable device worn by a subject, and measures the contraction and relaxation movements of the heart and the photoplethysmographic pulse wave signal. It is about a technology to estimate a subject's blood pressure through the characteristics of the correlation between the subjects.

As an example of a conventional technique for measuring blood pressure, blood pressure can be measured using an electrocardiogram (ECG) signal. ECG measures electrical signals that occur periodically during heartbeat and displays the changes graphically. Systolic and diastolic blood pressure can be measured through graph analysis.

In this method, in order to collect electrocardiogram signals, a closed loop must be formed so that two electrodes pass through the heart. This has the disadvantage of not being able to continuously collect data for blood pressure measurement during daily life because blood pressure can be measured only when the subject intentionally attempts to measure it.

As an example of another prior art, there is a method of simultaneously using electrocardiogram (ECG) and photoplethysmography (PPG). In this method, blood pressure can be measured using the time difference information from the Q-Peak point of the ECG to the Peak point of the PPG. For this purpose, the subject must wear both an ECG measurement device and a PPG measurement device. There is an inconvenience in that the subject must wear the ECG measurement device and the PPG measurement device separately on the body or wear a large, integrated device. Additionally, since a closed loop must be formed to measure ECG, there is a disadvantage in that data cannot be collected during daily life.

Korean Patent Registration No. 10-2362454 Korean Patent Registration No. 10-1503604

The present invention was developed to solve the problems of the prior art as described above, and aims to propose a method for measuring blood pressure more easily and conveniently by estimating blood pressure using only photoplethysmographic (PPG) signals.

In particular, in the case of the prior art, in order to measure blood pressure, the subject seeks to solve the inconvenience of having to contact the measuring device with both hands, etc. to perform the measurement or wearing multiple measuring devices or bulky measuring devices.

Furthermore, in the case of the prior art, in order to measure blood pressure, the subject must intentionally perform measurement using a measuring device, so it is intended to solve the problem that it is impossible to unconsciously and continuously collect blood pressure measurement data during daily life.

The object of the present invention is not limited to the above, and other objects and advantages of the present invention that are not mentioned can be understood by the following description.

One embodiment of the blood pressure estimation method according to the present invention includes a PPG signal acquisition step in which the blood pressure estimation device acquires a photoplethysmographic (PPG) signal of a subject; A level setting step in which the blood pressure estimating device sets a peak level as an average value of values included in a peak detection range in the PPG signal and sets a foot level as an average value of values included in a foot detection range in the PPG signal; And the blood pressure estimation device estimates the diastolic blood pressure of the subject based on the amount of change in the peak level compared to the peak level and the peak reference value, and estimates the subject's diastolic blood pressure based on the amount of change in the foot level compared to the foot level and the foot reference value. It may include a blood pressure estimation step of estimating the systolic blood pressure.

Preferably, the blood pressure estimation device is an estimation standard for setting a peak reference value and a foot reference value by comparing the peak level and foot level initially calculated for the subject with the diastolic blood pressure and systolic blood pressure of the subject measured through a medical device. Additional setup steps may be included.

As an example, in the estimation standard setting step, the blood pressure estimation device first calculates the first peak level and first foot level for the subject with the first peak level and first foot level measured through a medical device at the time of calculating the first level. An estimate setting step of setting a peak reference value and a foot reference value in comparison with the subject's first diastolic blood pressure and first systolic blood pressure; The blood pressure estimation device calculates a peak reference change value and a foot reference change value by comparing the second peak level and the second foot level calculated for the subject with the first peak level and the first foot level, At the time of calculation of the second level, the subject's secondary diastolic blood pressure and secondary systolic blood pressure measured through a medical device are compared with the primary diastolic blood pressure and primary systolic blood pressure to calculate the diastolic reference change value and systolic reference conversion value. a change value calculation step; And a scale setting step in which the blood pressure estimation device sets a peak change scale by matching the diastolic reference change value to the peak reference change value, and sets a foot change scale by matching the systolic reference change value with the foot reference change value. You can.

As an example, in the blood pressure estimation step, the blood pressure estimation device calculates a change in the peak level by comparing the peak level with the peak reference value, and calculates a change in the foot level by comparing the foot level with the foot reference value. step; It may include a blood pressure calculation step of estimating the subject's diastolic blood pressure by applying the peak change scale to the peak level change amount, and estimating the subject's systolic blood pressure by applying the foot change scale to the foot level change amount.

As an example, the PPG signal acquisition step removes impulse noise from the acquired PPG signal through a median filter, removes high-frequency noise through a mean filter, and produces a PPG signal from which the noise has been removed. It can be extracted.

Furthermore, it further includes a window setting step of setting a window for blood pressure estimation in the obtained PPG signal, and the level setting step can detect a value existing on the window of the PPG signal.

As an example, in the window setting step, a section in which the peak included in the peak detection range in the PPG signal satisfies the reference peak number and the foot included in the foot detection range satisfies the reference number of feet may be set as a window. there is.

In addition, one embodiment of the blood pressure estimation device according to the present invention is a wearable device that can be worn on a subject's body, comprising: a PPG signal acquisition unit that irradiates light to the subject's body and receives reflected light to obtain a PPG signal; a level setting unit that sets the peak level as the average of the values included in the peak detection range in the PPG signal and sets the foot level as the average of the values included in the foot detection range in the PPG signal; And a blood pressure estimation unit that estimates the subject's diastolic blood pressure based on the change in the peak level compared to the peak level and the peak reference value, and estimates the subject's systolic blood pressure based on the change in the foot level compared to the foot level and the foot reference value. can do.

Preferably, the subject's diastolic blood pressure and systolic blood pressure measured through a medical device are input, and the peak level and foot level initially calculated for the subject are compared with the subject's diastolic blood pressure and systolic blood pressure measured through the medical device. It may further include a reference value setting unit for setting the peak reference value and the foot reference value.

As an example, the reference value setting unit may set the first peak level and first foot level calculated for the subject as the first diastolic blood pressure and 1 of the subject measured through a medical device at the time of calculating the first level. The peak reference value and foot reference value are set in comparison with the primary systolic blood pressure, and the second peak level and second foot level calculated for the subject are compared with the first peak level and the first foot level to set the peak standard. Calculate the change value and foot reference change value, and compare the subject's second diastolic blood pressure and second systolic blood pressure measured through a medical device with the first diastolic blood pressure and first systolic blood pressure at the time of calculating the second level. Calculating a diastolic reference change value and a systolic reference change value, setting a peak change scale by matching the diastolic reference change value with the peak reference change value, and setting a foot change scale by matching the systolic reference change value with the foot reference change value, The blood pressure estimation unit calculates a peak level change amount by comparing the peak level with the peak reference value, calculates a foot level change amount by comparing the foot level with the foot reference value, and applies the peak change scale to the peak level change amount. The subject's diastolic blood pressure can be estimated, and the subject's systolic blood pressure can be estimated by applying the foot change scale to the foot level change amount.

As an example, impus noise is removed from the PPG signal acquired by the PPG signal acquisition unit through a median filter, and high-frequency noise is removed through a mean filter to produce a noise-removed PPG signal. It may further include a noise filtering unit for extracting noise.

Furthermore, the level setting unit may set a window for blood pressure estimation in the PPG signal and detect a value existing on the window of the PPG signal.

As an example, the level setting unit may set a window as a section in which peaks included in the peak detection range of the PPG signal meet the reference number of peaks and feet included in the foot detection range meet the reference number of feet.

According to the present invention, blood pressure can be estimated only with a photoplethysmographic (PPG) signal, making it possible to measure blood pressure more easily and conveniently.

In particular, the inconvenience of having to measure blood pressure by having the subject touch the measuring device with both hands or wear multiple measuring devices or bulky measuring devices can be resolved. In order to measure blood pressure, the subject must intentionally measure the measurement. Since measurements must be performed through a device, it can solve the problem of making it impossible to unconsciously collect continuous blood pressure measurement data during daily life.

Furthermore, the peak detection range and foot detection range are set considering various factors according to the subject's characteristics, such as the subject's race, skin thickness, skin elasticity, and age, and the peak reference value and foot reference value corresponding to the subject are set, The accuracy of blood pressure estimation for the subject can be improved.

The effects of the present invention are not limited to those mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description below.

Figure 1 shows a configuration diagram of an embodiment of a blood pressure estimation device according to the present invention.
2 and 3 show an implementation example of a blood pressure estimation device according to the present invention.
Figure 4 shows a flow chart of one embodiment of the blood pressure estimation method according to the present invention.
Figure 5 shows a flowchart of an embodiment of the process of acquiring a PPG signal and setting a peak level and a foot level in the blood pressure estimation method according to the present invention.
Figures 6 to 8 show an example of detecting values included in the peak detection range and foot detection range in the PPG signal through the present invention.
Figure 9 shows a flowchart of an embodiment of setting a reference value in the blood pressure estimation method according to the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, but the present invention is not limited or restricted by the embodiments.

In order to explain the present invention, its operational advantages, and the purpose achieved by practicing the present invention, preferred embodiments of the present invention are illustrated and discussed with reference to them.

First, the terms used in this application are only used to describe specific embodiments and are not intended to limit the present invention, and singular expressions may include plural expressions unless the context clearly indicates otherwise. In addition, in the present application, terms such as "comprise" or "have" are intended to designate the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, but are not intended to indicate the presence of one or more other It should be understood that this does not exclude in advance the presence or addition of features, numbers, steps, operations, components, parts, or combinations thereof.

In describing the present invention, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present invention, the detailed description will be omitted.

The present invention measures a photoplethysmography (PPG) signal through a wearable device worn by the subject, and estimates the subject's blood pressure through the characteristics of the correlation between the contraction and relaxation movements of the heart and the photoplethysmography signal. presents.

When the heart contracts, the light absorption rate of blood vessels increases due to an increase in blood volume, so the PPG signal has a low value. Additionally, when the heart relaxes, the light absorption rate of blood vessels decreases due to a decrease in blood volume, so the PPG signal has a high value. Using these characteristics, the present invention proposes a method of estimating diastolic blood pressure through the peak level in the PPG signal and estimating systolic blood pressure through the foot level.

FIG. 1 shows a configuration diagram of an embodiment of a blood pressure estimating device according to the present invention, and FIGS. 2 and 3 show an implementation example of the blood pressure estimating device according to the present invention.

The blood pressure estimation device 100 may include a PPG signal acquisition unit 110, a noise filtering unit 130, a level setting unit 150, a reference value setting unit 170, a blood pressure estimating unit 190, etc.

As an example, the blood pressure estimation device 100 may be implemented as a wearable device such as the smart watch 200a shown in (a) of FIG. 2 above.

As another example, the PPG signal acquisition unit 110 of the blood pressure estimation device 100 is implemented as a wearable device such as the smart watch 210b shown in (b) of FIG. 2, and other components are implemented as a smart phone 230b. ), the smart watch 210b and the smartphone 230b may be interconnected to form a blood pressure estimation device 200b. These smart watches may be equipped with a PPG sensor that can measure PPG signals. Figure 2 is an example of the present invention, which can be implemented with various wearable devices that can be worn on the subject's body in addition to a smart watch.

The PPG signal acquisition unit 110 can measure a photoplethysmographic (PPG) signal for the subject. For this purpose, the PPG signal acquisition unit 110 may include a PPG sensor.

The PPG sensor of the PPG signal acquisition unit 110 may be mounted on one surface of various wearable devices that come into contact with the subject's skin.

For example, when applying the blood pressure estimating device 300 in the form of a smart watch as shown in FIG. 3, the PPG sensor 350 may be mounted on one side of the body 310 of the smart watch that is in contact with the subject's skin. Through these wearable devices, the PPG signal of a subject can be measured periodically or selectively even in normal times when the subject is not conscious of measuring blood pressure.

The PPG sensor includes a light-emitting element and a light-receiving element and can measure the PPG signal by emitting light to the subject's skin and receiving reflected light. The light emitted from the PPG sensor may reach the arterial blood vessels, and some of the light that reaches the arterial blood vessels may be absorbed by the blood and some may be reflected. The PPG sensor can receive light reflected from arterial blood vessels. The PPG signal acquisition unit 110 may acquire a PPG signal through reflected light obtained through a PPG sensor.

In the present invention, blood pressure can be estimated using the following characteristics of the correlation between the contraction and relaxation movements of the heart and the PPG signal. When the heart contracts, the light absorption rate of blood vessels increases due to an increase in blood volume, so the PPG signal has a low value. Additionally, when the heart relaxes, the light absorption rate of blood vessels decreases due to a decrease in blood volume, so the PPG signal has a high value.

Since various known technologies may be applied to the specific details of how the PPG signal acquisition unit 110 acquires the subject's PPG signal through the PPG sensor, detailed description will be omitted.

The noise filtering unit 130 can remove noise from the PPG signal. The PPG signal acquired by the PPG signal acquisition unit 110 includes noise such as impulse and high frequency. The noise filtering unit 130 can remove such noise from the PPG signal.

As an example, the noise filtering unit 130 may remove impus noise through a median filter. Additionally, the noise filtering unit 130 can remove high-frequency noise through a mean filter.

The level setting unit 150 detects values included in the peak detection range in the PPG signal and sets the peak level as the average of the detected values, detects values included in the foot detection range in the PPG signal, and sets the average value of the detected values. You can set the foot level with .

As an example, the level setting unit 150 may set a window for blood pressure estimation in the PPG signal and detect a value existing on the window of the PPG signal.

For example, the level setting unit 150 may set a window as a section in which peaks included in the peak detection range of the PPG signal meet the reference number of peaks and feet included in the foot detection range meet the reference number of feet. Alternatively, the level setting unit 150 may set a section for a certain period of time in the PPG signal as a window section.

The level setting unit 150 may extract the PPG signal section included in the peak detection range and the PPG signal section included in the foot detection range on the set window. Additionally, the level setting unit 150 may integrate the PPG signal section included in the peak detection range, calculate the average value, and set this as the peak level. Additionally, the level setting unit 150 may integrate the PPG signal section included in the foot detection range, calculate the average value, and set this as the foot level.

The reference value setting unit 170 receives the subject's diastolic blood pressure and systolic blood pressure measured through a medical device, and inputs the peak level and foot level initially calculated for the subject and the subject's diastolic blood pressure and systolic blood pressure measured through the medical device. In preparation, you can set the peak reference value and put reference value.

As an example, the reference value setting unit 170 divides the first peak level and first foot level calculated for the subject into the subject's first diastolic blood pressure and first diastolic blood pressure measured through a medical device at the time of calculating the first level. You can set peak and foot reference values compared to systolic blood pressure. In addition, the peak-based change value and foot-based change value are calculated by comparing the second peak level and second foot level calculated for the subject with the first peak level and first foot level, and medical treatment is provided at the time of calculating the second level. By comparing the subject's secondary diastolic blood pressure and secondary systolic blood pressure measured through the device with the primary diastolic blood pressure and primary systolic blood pressure, the diastolic reference change value and systolic reference conversion value can be calculated. The reference value setting unit 170 may set the peak change scale by matching the diastolic reference change value to the peak reference change value, and set the foot change scale by matching the systolic reference change value with the foot reference change value.

The blood pressure estimation unit 190 estimates the subject's diastolic blood pressure based on the amount of change in the peak level compared to the peak level and the peak reference value, and estimates the subject's systolic blood pressure based on the amount of change in the foot level compared to the foot level and the foot reference value. It can be estimated.

As an example, the blood pressure estimation unit 190 may calculate the peak level change amount by comparing the peak level and the peak reference value, and calculate the foot level change amount by comparing the foot level and the foot reference value. Additionally, the blood pressure estimation unit 190 may estimate the subject's diastolic blood pressure by applying the peak change scale to the peak level change amount, and may estimate the subject's systolic blood pressure by applying the foot change scale to the foot level change amount.

The specific process of the level setting unit 150 setting the peak level and the foot level and the process of the blood pressure estimating unit 190 estimating the blood pressure based on the amount of change in the peak level and the amount of change in the foot level will be described later through specific embodiments. Let's do it.

In addition, the present invention presents a method of estimating blood pressure through the blood pressure estimating device according to the present invention described above. Hereinafter, the blood pressure estimating method according to the present invention will be described with reference to embodiments of the blood pressure estimating device according to the present invention. Let's look at it through examples.

Figure 4 shows a flow chart of one embodiment of the blood pressure estimation method according to the present invention.

The PPG signal acquisition unit 110 of the blood pressure estimation device 100 may periodically or selectively measure the PPG signal for the subject in a situation in which the subject is not conscious (S100).

When the PPG signal is acquired, the level setting unit 150 of the blood pressure estimation device 100 may set the peak level as the average of the values included in the peak detection range in the PPG signal (S200). Additionally, the foot level can be set (S300) as the average of the values included in the foot detection range in the PPG signal.

And the blood pressure estimation unit 190 of the blood pressure estimation device 100 compares the peak level and the peak reference value to estimate the subject's diastolic blood pressure based on the change in the peak level (S400), and compares the foot level with the foot reference value to estimate the subject's diastolic blood pressure. The subject's systolic blood pressure can be estimated (S500) based on the change in level (S400).

Each process of the blood pressure estimation method according to the present invention will be described in more detail through specific examples.

Figure 5 shows a flowchart of an embodiment of the process of acquiring a PPG signal and setting a peak level and a foot level in the blood pressure estimation method according to the present invention.

The PPG signal acquisition unit 110 of the blood pressure estimating device 100 may acquire a PPG signal (S110), and the acquired PPG signal may be filtered using a median filter (Median) in the noise filtering unit 130 of the blood pressure estimating device 100. Impulse noise is removed through a filter, and high-frequency noise is removed through a mean filter, so that the PPG signal can be extracted with the noise removed (S130).

The level setting unit 150 of the blood pressure estimation device 100 may set a window for blood pressure estimation in the PPG signal (S210).

As an example, the level setting unit 150 of the blood pressure estimation device 100 sets a section in the PPG signal where the peak included in the peak detection range satisfies the reference peak number and the foot included in the foot detection range satisfies the standard foot number. can be set to Windows. Alternatively, the level setting unit 150 of the blood pressure estimation device 100 may set a section for a certain period of time in the PPG signal as a window.

And the level setting unit 150 of the blood pressure estimation device 100 may detect values included in the peak detection range and values included in the foot detection range on the set window (S230).

A process in which the level setting unit 150 of the blood pressure estimation device 100 sets a window in the PPG signal and detects values included in the peak detection range and the foot detection range will be described with reference to examples of FIGS. 6 to 8.

When the noise-removed PPG signal 410 as shown in FIG. 6 is acquired, the acquired PPG signal 410 satisfies 4 reference peaks on the peak detection range PS and 4 reference foot numbers on the foot detection range FS. You can set the section as a window. With respect to FIG. 6, the number of reference peaks and the number of reference feet are described as four, but this is simplified for convenience of explanation. In reality, the number of reference peaks and the number of reference feet may be set to tens to hundreds.

As an example, the peak detection range PS can be set from the peak maximum value on the PPG signal to the peak threshold, and the peak threshold can be set as shown in [Equation 1] below.

[Equation 1]

Here, Peak _th represents the peak threshold, and Max is the peak maximum value. In the case of [Equation 1], the peak threshold was selected as 1% from the peak maximum value, but this can be optionally changed depending on the situation. For example, the selection may be made in consideration of various factors depending on the subject's characteristics, such as the subject's race, skin thickness, skin elasticity, and age.

Additionally, the foot detection range FS can be set from the minimum foot value on the PPG signal to the foot threshold, and the foot threshold can be set as shown in [Equation 2] below.

[Equation 2]

Here, Foot _th represents the foot threshold, and Min is the foot minimum value. In the case of [Equation 2] above, the foot threshold was selected as 0.5% from the foot minimum value, but this can be optionally changed depending on the situation. For example, the selection may be made in consideration of various factors depending on the subject's characteristics, such as the subject's race, skin thickness, skin elasticity, and age.

The peak value and the foot value are extracted from the section where the window as shown in FIG. 7 is set, the values existing in the peak detection range PS in the peak area 430 on the window and the values existing in the foot detection range FS in the foot area 450 on the window. Values can be extracted.

That is, the PPG signal section included in the peak detection range PS and the PPG signal section included in the foot detection range FS can be extracted from the window section of the PPG signal. When the corresponding PPG signal section is extracted in this way, the PPG signal section 431 included in the peak detection range PS as shown in (a) of FIG. 8 and the PPG included in the foot detection range FS as shown in (b) of FIG. 8 The signal section 451 can be extracted.

Figures 6 to 8 illustrate the extraction of corresponding values from the PPG signal in a simplified manner for convenience of explanation, but in reality, dozens to hundreds of signal sections can be extracted from a window.

Returning again to FIG. 6, the subsequent process will be described.

The level setting unit 150 of the blood pressure estimation device 100 calculates the average value of the values extracted from the peak detection range and sets this as the peak level (S250), and calculates the average value of the values extracted from the foot detection range and sets it as the peak level (S250). It can be set to level (S250).

As an example, the peak level can be set by integrating the PPG signal sections extracted from the peak detection range and calculating the average value, and the foot level can be set by integrating the PPG signal sections extracted from the foot detection range and calculating the average value. You can.

When the peak level and foot level are set from the PPG signal, the blood pressure estimation unit 190 of the blood pressure estimation device 100 estimates the subject's diastolic blood pressure based on the change in the peak level by comparing the peak level and the peak reference value, and By comparing the level and foot reference value, the subject's systolic blood pressure can be estimated based on the change in foot level.

To achieve this, the peak reference value and the foot reference value must be set in advance, and FIG. 9 shows a flowchart of one embodiment of reference value setting in the blood pressure estimation method according to the present invention.

Before estimating the subject's blood pressure through the blood pressure estimating device 100, measure the subject's diastolic blood pressure and systolic blood pressure using a medical device and simultaneously measure the PPG signal for the subject through the blood pressure estimating device 100 (S10). You can set the peak level and foot level from the PPG signal (S30). Here, the process of setting the peak level and foot level from the PPG signal is the same or similar to that described previously, so description thereof will be omitted.

The reference value setting unit 170 of the blood pressure estimation device 100 sets the peak reference value (S60) by matching the peak level to the diastolic blood pressure (S50), and sets the foot reference value by matching the foot level to the systolic blood pressure (S50) ( S60) You can do it.

For example, if the size of the peak level calculated through the blood pressure estimation device 100 is 6500 and the diastolic blood pressure measured through the medical device at the time of calculating the peak level is 80 mmHg, the diastolic blood pressure 80 mmHg is matched to the peak level 6500 to obtain the peak level. Set a standard value. In other words, the peak level of 6500, which is the peak reference value, can be treated the same as the diastolic blood pressure of 80 mmHg. Likewise, the foot reference value is set by matching the foot level and the corresponding systolic blood pressure, and the foot level, which is the foot reference value, can be treated the same as the corresponding systolic blood pressure.

In this way, the peak reference value and the foot reference value can be set at the beginning when the subject uses the blood pressure estimation device, and then the blood pressure can be estimated for the subject through the peak reference value and the foot reference value.

That is, by comparing the peak level calculated for the subject with the peak reference value, it is possible to estimate how much blood pressure change has occurred from the diastolic blood pressure matched to the peak reference value based on the amount of change in the peak level from the peak reference value.

Similarly, by comparing the foot level calculated for the subject with the foot reference value, it is possible to estimate how much blood pressure change has occurred from the systolic blood pressure matched to the foot reference value based on the amount of change in the foot level from the foot reference value.

Furthermore, it is possible to set a peak change scale for the amount of change in the peak level and a foot change scale for the amount of change in the foot level, and estimate blood pressure based on these.

For this purpose, the reference value setting unit 170 of the blood pressure estimation device 100 sets the first peak level and first foot level calculated for the subject as the 1st peak level and the first foot level of the subject measured through a medical device at the time of calculating the first level. The peak reference value and foot reference value can be set by matching the first diastolic blood pressure and the first systolic blood pressure. This is the same as the standard setting process described previously.

Next, the reference value setting unit 170 of the blood pressure estimation device 100 compares the second peak level and second foot level calculated secondarily for the same subject with the first peak level and first foot level calculated previously. Calculate the peak-based change value and the put-based change value, and compare the subject's secondary diastolic blood pressure and secondary systolic blood pressure measured using the medical device at the time of calculating the secondary level with the previously measured primary diastolic blood pressure and primary systolic blood pressure. Thus, the diastolic reference change value and the systolic reference conversion value can be calculated.

Additionally, the reference value setting unit 170 of the blood pressure estimation device 100 may set the peak change scale by matching the diastolic reference change value with the peak reference change value, and set the foot change scale by matching the systolic reference change value with the foot reference change value.

For example, if the size of the first peak level is 6500 and the first diastolic blood pressure is matched to 80mmHg to set the peak reference value, then the size of the second peak level is calculated to be 6400 and the second diastolic blood pressure is measured to be 90mmHg, the peak reference value is The change value is calculated as -100 between the size of the first peak level of 6500 and the size of the second peak level of 6400, and the diastolic standard change value can be calculated as +10 mmHg between the first diastolic blood pressure of 80 mmHg and the second diastolic blood pressure of 90 mmHg.

In this case, the peak change scale can be set by matching the change in diastolic blood pressure +10 mmHg to the change in peak level -100.

Additionally, the put change scale can be set through the same process.

When such a peak change scale and a foot change scale are set, the blood pressure estimation unit 190 of the blood pressure estimation device 100 compares the peak level with the peak reference value when the peak level and foot level for the subject are set to determine the peak level change amount. After calculating the foot level change amount by comparing the foot level with the foot reference value, the subject's diastolic blood pressure can be estimated by applying the peak change scale to the peak level change amount, and applying the foot change scale to the foot level change amount to estimate the subject's diastolic blood pressure. Systolic blood pressure can be estimated.

For example, when the peak change scale is set as described above, if the newly measured peak level for the subject is calculated as 6300, the peak level change between the peak level of 6300 and the peak reference value of 6500 may be calculated as -200. When applied to the peak change scale here, the peak change scale is -100 change in peak level and +10 mmHg change in diastolic blood pressure, so if the change in peak level is -200, diastolic blood pressure becomes +20 mmHg, and the estimated diastolic blood pressure is 100 mmHg. can be calculated.

In the same process, systolic blood pressure can be estimated by applying the foot change scale.

Through the present invention discussed above, blood pressure can be estimated using only a photoplethysmographic (PPG) signal, making it possible to measure blood pressure more easily and conveniently.

In particular, the inconvenience of having to measure blood pressure by having the subject touch the measuring device with both hands or wear multiple measuring devices or bulky measuring devices can be resolved. In order to measure blood pressure, the subject must intentionally measure the measurement. Since measurements must be performed through a device, it can solve the problem of making it impossible to unconsciously collect continuous blood pressure measurement data during daily life.

Furthermore, the peak detection range and foot detection range are set considering various factors according to the subject's characteristics, such as the subject's race, skin thickness, skin elasticity, and age, and the peak reference value and foot reference value corresponding to the subject are set, The accuracy of blood pressure estimation for the subject can be improved.

The above description is merely an illustrative explanation of the technical idea of the present invention, and various modifications and variations will be possible to those skilled in the art without departing from the essential characteristics of the present invention. Accordingly, the embodiments described in the present invention are not intended to limit the technical idea of the present invention, but are for illustrative purposes, and the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be interpreted in accordance with the claims below, and all technical ideas within the equivalent scope should be construed as being included in the scope of rights of the present invention.

100: blood pressure estimation device,
110: PPG signal acquisition unit,
130: noise filtering unit,
150: level setting unit,
170: standard value setting unit,
190: Blood pressure estimation unit.

Claims (13)

A PPG signal acquisition step in which the blood pressure estimation device acquires a photoplethysmographic (PPG) signal of a subject;
A level setting step in which the blood pressure estimating device sets a peak level as an average value of values included in a peak detection range in the PPG signal and sets a foot level as an average value of values included in a foot detection range in the PPG signal; and
The blood pressure estimation device estimates the diastolic blood pressure of the subject based on the amount of change in the peak level compared to the peak level and the peak reference value, and estimates the subject's diastolic blood pressure based on the amount of change in the foot level compared to the foot level and the foot reference value. A blood pressure estimation method comprising a blood pressure estimation step of estimating systolic blood pressure. According to claim 1,
The blood pressure estimation device sets the peak reference value and foot reference value by matching the peak level and foot level initially calculated for the subject with the diastolic blood pressure and systolic blood pressure of the subject measured through a medical device at the time of calculating the first level. A blood pressure estimation method further comprising the step of setting an estimation standard. According to claim 2,
The estimation standard setting step is,
The blood pressure estimation device calculates the first peak level and first foot level for the subject by calculating the first diastolic blood pressure and first systolic blood pressure of the subject measured through a medical device at the time of calculation of the first level. An estimate setting step of matching the blood pressure and setting the peak reference value and foot reference value;
The blood pressure estimation device calculates a peak reference change value and a foot reference change value by comparing the second peak level and the second foot level calculated for the subject with the first peak level and the first foot level, At the time of calculation of the second level, the subject's secondary diastolic blood pressure and secondary systolic blood pressure measured through a medical device are compared with the primary diastolic blood pressure and primary systolic blood pressure to calculate the diastolic reference change value and systolic reference conversion value. a change value calculation step; and
The blood pressure estimation device includes a scale setting step of setting a peak change scale by matching the diastolic reference change value to the peak reference change value, and setting a foot change scale by matching the systolic reference change value with the foot reference change value. Characterized blood pressure estimation method. According to claim 3,
The blood pressure estimation step is,
A change calculation step in which the blood pressure estimation device calculates a peak level change amount by comparing the peak level with the peak reference value, and calculates a foot level change amount by comparing the foot level with the foot reference value;
A blood pressure calculation step of estimating the diastolic blood pressure of the subject by applying the peak change scale to the peak level change amount, and estimating the systolic blood pressure of the subject by applying the foot change scale to the foot level change amount. How to estimate blood pressure. According to claim 1,
The PPG signal acquisition step is,
A blood pressure estimation method characterized by removing impulse noise from the acquired PPG signal through a median filter and removing high-frequency noise through a mean filter to extract a PPG signal from which the noise has been removed. According to claim 1,
Further comprising a window setting step of setting a window for blood pressure estimation from the acquired PPG signal,
The level setting step is,
A blood pressure estimation method characterized by detecting a value existing on a window of the PPG signal. According to claim 6,
The window setting step is,
A blood pressure estimation method characterized by setting a window as a section in which peaks included in the peak detection range in the PPG signal meet a reference peak number, and feet included in the foot detection range meet the reference number of feet. A wearable device that can be worn on a subject's body, comprising: a PPG signal acquisition unit that radiates light to the subject's body and receives reflected light to obtain a PPG signal;
a level setting unit that sets the peak level as the average of the values included in the peak detection range in the PPG signal and sets the foot level as the average of the values included in the foot detection range in the PPG signal; and
A blood pressure estimation unit that estimates the subject's diastolic blood pressure based on the change in the peak level compared to the peak level and the peak reference value, and estimates the subject's systolic blood pressure based on the change in the foot level compared to the foot level and the foot reference value. A blood pressure estimation device characterized in that. According to claim 8,
The subject's diastolic blood pressure and systolic blood pressure measured through the medical device are input, and the peak level and foot level initially calculated for the subject are matched with the subject's diastolic blood pressure and systolic blood pressure measured through the medical device to determine the peak reference value and A blood pressure estimation device further comprising a reference value setting unit for setting a foot reference value. According to clause 9,
The standard value setting unit,
The peak reference value is established by matching the first peak level and first foot level calculated for the subject with the subject's first diastolic blood pressure and first systolic blood pressure measured through a medical device at the time of calculation of the first level. And set a foot reference value, and compare the second peak level and the second foot level calculated for the subject with the first peak level and the first foot level to calculate the peak reference change value and the foot reference change value, , The subject's secondary diastolic blood pressure and secondary systolic blood pressure measured through a medical device at the time of calculating the secondary level are compared with the primary diastolic blood pressure and primary systolic blood pressure to obtain a diastolic reference change value and a systolic reference conversion value. Calculating, setting a peak change scale by matching the diastolic reference change value to the peak reference change value, and setting a foot change scale by matching the systolic reference change value with the foot reference change value,
The blood pressure estimation unit,
Compare the peak level with the peak reference value to calculate the peak level change, calculate the foot level change by comparing the foot level with the foot reference value, and apply the peak change scale to the peak level change to determine the subject's diastolic phase. A blood pressure estimation device that estimates blood pressure and applies the foot change scale to the foot level change amount to estimate the subject's systolic blood pressure. According to claim 8,
Impus noise is removed from the PPG signal acquired in the PPG signal acquisition unit through a median filter, and high-frequency noise is removed through a mean filter to extract the noise-removed PPG signal. A blood pressure estimation device further comprising a filtering unit. According to claim 8,
The level setting unit,
A blood pressure estimation device characterized by setting a window for blood pressure estimation in the PPG signal and detecting the value existing on the window of the PPG signal. According to claim 12,
The level setting unit,
A blood pressure estimation device characterized by setting a window as a section in which peaks included in the peak detection range of the PPG signal meet the reference number of peaks, and feet included in the foot detection range meet the reference number of feet.

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