KR20160007056A - Apparatus and method for estimating aortic blood pressure in patients with atrial fibrillation - Google Patents

Abstract

The present invention relates to an apparatus and method for estimating aortic blood pressure. The present invention provides an apparatus for estimating noninvasive aortic blood pressure which is configured to strongly estimate aortic blood pressure for patients with atrial fibrillation who have unstable pulse due to irregular heartbeat. The method comprises the following steps of: measuring a blood pressure waveform of a peripheral blood vessel, dividing the waveform by a period unit by detecting the highest point of the blood pressure waveform; measuring blood pressure information separately from the blood pressure waveform, correcting a blood pressure unit of the blood pressure waveform by using the blood pressure information; designing a prediction filter in which frequency response properties is adaptively changed according to properties of the blood pressure waveform; and measuring aortic blood pressure from the blood pressure waveform by using the prediction filter. In addition, the present invention provides a method for noninvasively estimating aortic blood pressure by using the apparatus.

Description

TECHNICAL FIELD The present invention relates to a non-invasive aortic blood pressure estimation apparatus applicable to patients with atrial fibrillation,

The present invention relates to an aortic blood pressure estimation apparatus and a method thereof.

The heart of the body periodically beats and sends blood to the entire body from the heart to peripheral blood vessels. The pressure on the blood vessel wall in the process of blood flowing along the blood vessel is called blood pressure. In addition, the heart repeats contraction and relaxation while pulsating. The systolic blood pressure is called the systolic blood pressure when the heart's ventricle contracts and the blood is pushed into the artery. It is called the systolic blood pressure because it is the highest systolic blood pressure. The diastolic blood pressure is referred to as diastolic blood pressure or diastolic blood pressure.

As the heart periodically pulses, the blood pressure changes periodically between the systolic and diastolic blood pressure, and the periodic fluctuation of the blood pressure is referred to as a pulse, and the waveform is referred to as a pulse wave or a blood pressure waveform. The blood pressure waveform according to the change of the pulse is affected by the pulsating force of the heart, the beating state, the elasticity of the blood vessel, the viscosity of the blood, and has different sizes and shapes depending on the positions of the arteries, veins and capillaries.

As a method of measuring blood pressure, there is an invasive method of measuring blood pressure with a pressure gauge by inserting a measuring device into a blood vessel, and a non-invasive method of measuring blood pressure by sensing blood flow from a sensor outside the body. Noninvasive blood pressure measurement methods generally use a method of measuring the changing blood pressure as the upper arm compresses with pressure and relaxes. In order to measure the pulse more precisely, the blood pressure may be measured noninvasively by contacting the tonometry on the skin passing through the blood vessel and measuring the vibration as the blood pressure changes in the blood vessel.

Because the aorta is located deep inside the body, it is necessary to measure and detect the blood pressure waveform non-invasively in the peripheral blood vessels such as the radial artery above the wrist and measure the blood pressure value non-invasively. A method of estimating the blood pressure is used. However, since the conventional aortic blood pressure estimating apparatus is designed assuming a stable heartbeat, the blood pressure waveform of the atrial fibrillation patient having irregular heartbeat can not reliably detect the heartbeat cycle and can not correct the blood pressure unit correctly , There is a problem that the aortic blood pressure can not be correctly estimated from the irregular pulse change.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a blood pressure measuring apparatus and a blood pressure measuring method which measure blood pressure waveforms of peripheral blood vessels, detect a peak of the blood pressure waveforms, divide the waveform into periods, measure blood pressure information separately from the blood pressure waveforms, A prediction filter in which the frequency response characteristic is adaptively changed according to the characteristics of the blood pressure waveform is designed and the aortic blood pressure is estimated from the blood pressure waveform using the prediction filter, The present invention also provides a device for estimating the aortic blood pressure of an atrial fibrillation patient having an unstable pulse due to irregular heartbeat, and a method for estimating the aortic blood pressure using the same.

According to one aspect of the present invention, an aortic blood pressure estimation apparatus includes: a blood pressure waveform analyzer that receives a pulse wave signal and acquires blood pressure waveform information including diastolic blood pressure and pulse wave period information using the pulse wave signal; A prediction filter unit having a prediction filter capable of variably controlling the filter coefficient, filtering the pulse wave signal with the prediction filter, and analyzing the filtered signal to estimate the aortic blood pressure; And a prediction filter coefficient adjustment unit for calculating a filter coefficient of a prediction filter of the prediction filter unit based on the blood pressure waveform information obtained by the blood pressure waveform analyzing unit and adjusting the filter coefficient of the prediction filter adaptively according to the pulse wave signal And the like.

According to one embodiment, the pulse wave signal is a signal obtained by measuring a waveform of a pulse of a body, detecting the waveform by periodic unit, calibrating a blood pressure unit of the waveform, and calculating a systolic Blood pressure, diastolic blood pressure information, and pulse wave period information.

According to one embodiment, the prediction filter coefficient adjuster may calculate the filter coefficient of the prediction filter based on the diastolic blood pressure and the pulse wave period in the blood pressure waveform information calculated from the pulse wave signal.

According to one embodiment, the predictive filter coefficient adjuster determines a cutoff frequency of the first low-pass filter according to Equation 1 below, and the predictive filter adjusts the filter coefficient to be a first low-pass filter having the determined cutoff frequency value .

Equation 1.

(Where CF is a cut-off frequency of the prediction filter, a, b and c are constants having constant values, L is the pulse wave period, and DBP is the diastolic blood pressure).

According to an embodiment, the value a is 1.477 to 2.831, the value of b is 0.001 to 0.002, and the value of c is 0.004 to 0.018.

According to one embodiment, the prediction filter unit sets a filter coefficient of the prediction filter according to a filter coefficient value calculated by the prediction filter coefficient adjustment unit, filters the pulse wave signal with the set prediction filter, and outputs the filtered signal And estimating the aortic blood pressure.

The aorta blood pressure estimating apparatus may further include a pulse wave detecting unit that measures a pulse wave of a body blood vessel, detects a peak of the pulse wave, and detects the pulse wave classified in a cycle unit; And a pulse wave detector that receives the pulse wave detected by the pulse wave detector in units of a cycle and measures blood pressure information including blood pressure and blood pressure measurement time point information in a specific region of the body separately from the pulse wave, And a pulse wave unit analyzing unit for calibrating the detected pulse wave unit to obtain the pulse wave signal, wherein the blood pressure waveform analyzing unit receives the pulse wave signal from the pulse wave unit calibration unit.

According to one embodiment, the pulse-wave detecting unit includes a pulse-wave measuring unit for measuring a pulse of a blood vessel of a body, measuring a pulse, amplifying the pulse signal, and removing noise of the amplified pulse signal to obtain the pulse wave; A low-pass filter unit having a second low-pass filter capable of variably controlling a filter coefficient and filtering the pulse wave with the second low-pass filter to obtain a low-frequency signal; A filter coefficient adjuster for adaptively adjusting a filter coefficient value of the second low-pass filter according to characteristics of the pulse wave; A pulse wave peak detector for detecting a peak of the pulse wave using the low frequency signal obtained by the low pass filter; And a cycle unit pulse wave detecting unit for detecting the pulse wave divided by the cycle unit by using the peak information of the pulse wave detected by the pulse wave peak detecting unit.

According to an embodiment, the filter coefficient adjustment unit may obtain a signal obtained by removing a linear trend, which is a linear component having a constant slope, from the signal of the pulse wave, and subtracts the linear tendency from the obtained signal to obtain a finite length A window function which is a function having a specific value in a section of the window function to obtain a signal limited to a predetermined length and transforms the signal obtained by applying the window function into a frequency domain signal, A heart rate calculation unit for calculating an average heart rate of the pulse wave for a predetermined time by analyzing a signal of a region; And a filter coefficient calculator for calculating a filter coefficient value of the second low-pass filter so that the cut-off frequency of the second low-pass filter is a predetermined multiple of the average heart rate calculated by the heart rate calculator, And adjusts the filter coefficient value of the second low-pass filter according to the average heart rate when the heart rate value fluctuates.

According to an embodiment, the pulse wave peak detector may further include: a differential section for differentiating the low-frequency signal obtained by the low-pass filter section; A zero crossing point detecting unit for detecting the zero crossing point of the differentiated signal in the differential unit; And a local maximum point detecting unit for detecting a maximum point of the pulse wave within a predetermined time interval based on the zero crossing point detected by the zero crossing point detecting unit, wherein the peak detecting unit detects the peak of the low frequency signal obtained by the low pass filter unit, And the peak of the pulse wave is detected within a predetermined time interval from the peak of the low-frequency signal.

According to one embodiment, the pulse-wave unit calibration unit includes: a blood pressure measurement unit that measures the blood pressure information including the blood pressure and the blood pressure measurement time point information of the specific part of the body; A pulse wave detector for detecting a pulse wave, a pulse wave detector for detecting a pulse wave, a pulse wave detector for detecting a pulse wave, a pulse wave detector for detecting a pulse wave, A pulse-wave specifying unit that specifies the pulse wave of one cycle and specifies the cycle of the pulse wave corresponding to the blood pressure measurement time; And a unit for correcting the pulse wave unit of one period specified by the pulse wave specifying unit based on the blood pressure measured by the blood pressure measuring unit, And a calibration unit for calibration.

According to one embodiment, the blood pressure measuring unit includes: a sensor unit for measuring a blood pressure while pressing and relaxing a specific part of the body; A sensor driver for driving the sensor unit; An amplifying unit for amplifying the blood pressure signal measured by the sensor unit; A noise removal filter unit for removing noise of the blood pressure signal amplified by the amplification unit through filtering; And a blood pressure information calculation unit for analyzing the blood pressure signal from which noise has been removed from the noise canceling filter unit and calculating the blood pressure information including the blood pressure and the blood pressure measurement time point information.

According to one embodiment, the pulse-wave specifying unit makes a tangent line around the highest point of the first-order differential signal of the pulse wave, creates a horizontal line connecting the lowest points of the pulse wave, And the start point of each pulse of the pulse wave is detected using an intersecting tangent method, which is a method of determining the start point of the pulse wave.

In another aspect of the present invention, an aortic blood pressure estimation method includes: measuring a waveform of a pulse of a body; detecting the waveform by a period unit; calibrating a blood pressure unit of the waveform; Analyzing blood pressure waveform information including diastolic blood pressure and pulse wave period information; Calculating a filter coefficient of a prediction filter capable of variably controlling a filter coefficient based on the diastolic blood pressure and the pulse wave period information among the blood pressure waveform information; And estimating the aortic blood pressure by filtering the pulse wave signal with the prediction filter having the calculated filter coefficient and analyzing the filtered signal.

According to one embodiment, calculating the filter coefficient of the prediction filter may include: determining a cut-off frequency of the first low-pass filter according to Equation 2 below, and wherein the prediction filter includes a first low- And the filter coefficient is calculated so as to be a filter.

Equation 2.

(Where CF is a cut-off frequency of the prediction filter, a, b and c are constants having constant values, L is the pulse wave period, and DBP is the diastolic blood pressure).

According to an embodiment, the value a is 1.477 to 2.831, the value of b is 0.001 to 0.002, and the value of c is 0.004 to 0.018.

The aorta blood pressure estimation method may further include measuring a pulse wave of a body vessel and detecting the pulse wave classified by a cycle unit; And measuring blood pressure information including blood pressure and blood pressure measurement point-in-time information at a specific part of the body, calibrating a unit of the pulse wave detected by the period unit based on the blood pressure information, The method further comprising the steps of:

According to an embodiment of the present invention, the step of detecting the pulse wave classified by the cycle unit includes the steps of: measuring blood pressure of a body vessel to obtain the pulse wave; A linear function, which is a linear component having a constant slope, is removed from the signal of the pulse wave, and a window function, which is a function having a specific value in a section of a finite length, is applied to the signal obtained by removing the linear tendency A signal obtained by applying the window function is converted into a frequency domain signal, and the average heart rate of the pulse wave for a predetermined time is calculated by analyzing the converted frequency domain signal And a filter coefficient value of a second low-pass filter which calculates the cut-off frequency of the second low-pass filter to be a predetermined multiple of the average heart rate calculated by the heart rate calculation unit. When the average heart rate is changed, Adjusting the filter coefficient value to a predetermined value; Filtering the pulse wave with the second low-pass filter having the calculated filter coefficient to obtain a low-frequency signal; And a second low pass filter for differentiating the signal filtered by the second low pass filter to detect the position of the zero crossing point of the differentiated signal and detecting the highest point of the obtained low frequency signal, Detecting a peak of the pulse wave at a predetermined time interval from a peak of the detected low frequency signal; And detecting the pulse wave divided by the cycle unit using the detected peak wave information of the pulse wave.

According to one embodiment, the step of acquiring the pulse wave signal with the blood pressure unit corrected includes: measuring blood pressure information including a blood pressure of a specific part of the body and blood pressure measurement time point information; Identifying the pulse wave of one cycle occurring after a predetermined period at the time of measuring the blood pressure among the pulse waves detected by the cycle unit; And calibrating a unit of the specified one cycle of the pulse wave with reference to the measured blood pressure and calibrating a unit of the pulse wave of the remaining cycles based on the corrected one cycle of the pulse wave to obtain the pulse wave signal The method comprising the steps of:

According to the present invention, in an apparatus and method for estimating aortic blood pressure, there is an effect of robustly estimating aortic blood pressure even in an atrial fibrillation patient having a pulse that is not stable due to irregular heart beat. In addition, the aortic blood pressure is also robustly estimated for a person having a stable pulse of a normal form.

1 is a block diagram illustrating an aortic blood pressure estimation apparatus according to an embodiment of the present invention.
2 is a block diagram illustrating a pulse wave detecting unit according to an embodiment of the present invention.
3 is a block diagram showing a filter coefficient adjusting unit according to an embodiment of the present invention.
4A is a reference view showing a frequency response characteristic of a second low-pass filter of a low-pass filter according to an embodiment of the present invention.
FIG. 4B is a reference diagram showing pulse waveforms of peripheral blood vessels before and after filtering by a low-pass filter according to an embodiment of the present invention.
FIG. 4C is a reference view showing pulse waveforms of the aorta and the aorta by comparing the pulse waveforms before and after filtering by the low-pass filter according to an embodiment of the present invention.
5 is a block diagram illustrating a pulse wave peak detector according to an embodiment of the present invention.
FIG. 6 is a reference view illustrating a process of detecting a peak of a pulse wave by a low-pass filter and a pulse-wave peak detector according to an embodiment of the present invention.
7 is a block diagram showing a pulse-wave-unit calibration unit according to an embodiment of the present invention.
8A is a reference diagram showing a peripheral blood pressure waveform in a normal state.
FIG. 8B is a reference diagram showing a waveform in which peripheral blood pressure waveforms of a plurality of periods in a steady state are superimposed. FIG.
8C is a reference diagram showing a peripheral blood pressure waveform in an atrial fibrillation patient having irregular heartbeats.
FIG. 8D shows waveforms of peripheral blood pressure waveforms of various periods shown in FIG. 8C, averaged peripheral blood pressure waveform (a thick gray line) when the waveforms are averaged, and an average of systolic blood pressure values of each cycle Line).
FIG. 8E is a graph showing a relationship between a pulse wave of a first period (a thick gray line) and a systolic blood pressure value of a pulse wave of the first period ) As a reference.
9 is a block diagram showing a blood pressure measuring unit according to an embodiment of the present invention.
10 is a detailed flowchart of a pulse wave detecting step of the aortic blood pressure estimation method according to another embodiment of the present invention.
11 is a detailed flowchart of a pulse-wave unit calibration step in the aortic blood pressure estimation method according to an embodiment of the present invention.
12 is a block diagram illustrating a method of estimating an aortic blood pressure according to an embodiment of the present invention.
FIG. 13 is a reference diagram showing a result of estimating aortic blood pressure of actual atrial fibrillation patients using an aortic blood pressure estimation apparatus according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to designate the same or similar components throughout the drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. In addition, the preferred embodiments of the present invention will be described below, but it is needless to say that the technical idea of the present invention is not limited thereto and can be variously modified by those skilled in the art.

1 is a block diagram illustrating an aortic blood pressure estimation apparatus according to an embodiment of the present invention. The aorta blood pressure estimation apparatus according to the present embodiment may include a pulse wave detector 100, a pulse wave unit calibration unit 200, a blood pressure waveform analysis unit 300, a prediction filter coefficient adjustment unit 400, and a prediction filter unit 500 have. The aortic blood pressure estimation apparatus including the pulse wave detecting unit 100, the pulse wave unit calibration unit 200, the blood pressure waveform analyzing unit 300, the prediction filter coefficient adjusting unit 400, and the prediction filter unit 500, This is the best embodiment. The aortic blood pressure estimating apparatus according to another embodiment of the present invention may include a blood pressure waveform analyzer 300, a predictive filter coefficient adjuster 400, and a predictive filter unit 500, Can measure the waveform of a pulse having no blood pressure unit according to the pulse of the body in various ways and receive a signal obtained by calibrating the blood pressure unit. Herein, the pulse-wave detecting unit 100 and the pulse-wave-unit calibrating unit 200 may be optionally included or omitted as needed.

Hereinafter, each part of the aortic blood pressure estimation apparatus will be described in more detail with respect to the above-described optimal embodiment.

The pulse wave detecting unit 100 measures a pulse wave SIG0 by detecting a pulse generated according to a change in blood pressure in a body blood vessel and detects a peak of the pulse wave to detect a pulse wave SIG1 classified on a cycle basis. The configuration and operation of the pulse-wave detecting unit 100 will be described in more detail with reference to FIG. 2 through FIG.

The pulse-wave unit calibration unit 200 receives the pulse wave SIG1 detected by the pulse-wave detecting unit 100 on a cycle-by-cycle basis and includes blood pressure and blood pressure measurement point-in-time information in a specific part of the body separately from the pulse wave SIG1 Measures the blood pressure information, calibrates the unit of the pulse wave SIG1 detected in the period unit based on the blood pressure information, and obtains the corrected pulse wave signal SIG2. Here, the pulse wave signal SIG2 is a signal obtained by measuring a waveform of a pulse of the body, detecting the waveform by periodic unit, calibrating a blood pressure unit of the waveform, and calculating a systolic blood pressure and a systolic blood pressure The diastolic blood pressure information and the pulse wave period information. The configuration and operation of the pulse-wave unit calibration unit 200 will be described in more detail below with reference to FIGS. 7 to 9. FIG.

The blood pressure waveform analyzing unit 300 receives the corrected pulse wave signal SIG2 and obtains blood pressure waveform information including the diastolic blood pressure and the pulse wave period information.

The prediction filter coefficient adjustment unit 400 calculates the filter coefficient of the prediction filter of the prediction filter unit 500, which will be described below, based on the blood pressure waveform information acquired by the blood pressure waveform analysis unit 300. [ The predictive filter coefficient adjuster 400 calculates the filter coefficient of the predictive filter of the predictive filter unit 500 based on the diastolic blood pressure and the pulse wave period information among the blood pressure waveform information obtained by the blood pressure waveform analyzer 300 can do. In this case, it is preferable that the cutoff frequency is calculated according to the following equation (1), and the filter coefficient is calculated so that the prediction filter of the prediction filter unit 500 becomes the first low-pass filter having the cutoff frequency value thus determined.

(Where CF is the cut-off frequency of the prediction filter of the prediction filter unit 500, a, b and c are constants having constant values, L is the pulse wave period, and DBP is the diastolic blood pressure).

Here, the value a is 1.477 to 2.831, the value b is 0.001 to 0.002, and the value of c is 0.004 to 0.018. Further, the value a is 2.188, the value b is 0.001, the value c is 0.011 It is preferable that a, b, and c have optimized values within the above ranges. If the above values exceed the range set by the statistical analysis, the cutoff frequency can not be calculated optimally, and there is a risk of inaccurate blood pressure estimation. The above equation (1) and the ranges and the optimized values of the constants are simultaneously measured at the peripheral arterial blood pressure and the aortic blood pressure of the atrial fibrillation patients, and the factors affecting the cutoff frequency of the prediction filter were found by linear regression analysis . This also applies to the following equation (3). The effect of the aortic blood pressure estimation when calculating the cut-off frequency by setting the a, b, c values as described above will be described in detail with reference to FIG. 13 below.

The predictive filter unit 500 includes a predictive filter capable of variably controlling the filter coefficient. The predictive filter unit 500 filters the pulse-wave signal SIG2 corrected by the BP unit with the predictive filter, analyzes the filtered signal, . At this time, the prediction filter unit 500 may set the filter coefficient of the prediction filter according to the filter coefficient value calculated by the prediction filter coefficient adjustment unit 400. [

Here, the prediction filter unit 500 can obtain the estimated aortic blood pressure signal by filtering the pulse wave signal SIG2 using the prediction filter as an FIR (Finite Impulse Response) filter as shown in Equation (2).

Wherein n is an index, h (n) is a filter coefficient of the prediction filter, N is a length of the predictive filter, x (n) is a pulse wave signal SIG2 in which the blood pressure unit is calibrated, n) is the estimated aortic blood pressure signal.

As described above, the predictive filter coefficient adjuster 400 and the predictive filter unit 500 adaptively adjust the filter coefficients of the predictive filter as the characteristic of the pulse wave SIG0 varies, and adaptively adjust the cutoff frequency of the predictive filter .

2 is a block diagram illustrating a pulse wave detector 100 according to an embodiment of the present invention. The pulse wave detecting unit 100 according to the present embodiment includes a pulse wave measuring unit 110, a low pass filter 120, a filter coefficient adjusting unit 130, a pulse wave peak detecting unit 140, and a cycle unit pulse wave detecting unit 150 .

The pulse-wave measuring unit 110 measures the pulse of the blood vessel of the body, amplifies the pulse signal, and removes the noise of the amplified pulse signal to obtain the pulse wave SIGO. At this time, it is preferable that the body blood vessel measuring the pulse is a radial artery, and the blood pressure change can be measured in a non-invasive manner by contacting a highly accurate tonometry with a point on the wrist passing through the radial artery. In the signal measured by the above-mentioned torque meter, the noise inserted in the measurement process can be filtered out to acquire the pulse wave of the radial artery. The pulse wave SIG0 measured by the pulse wave measuring unit 110 is a unitless signal, and the unit can be calibrated by the pulse wave unit calibration unit 200 described later. The pulse wave SIG0 thus obtained may be input to the low pass filter 120. [

The low-pass filter unit 120 includes a second low-pass filter capable of variably controlling a filter coefficient, and the low-pass signal is obtained by filtering the pulse wave SIGO with the second low-pass filter. At this time, the second low-pass filter can adjust the frequency response characteristic of the filter by variably controlling the filter coefficient. The filter coefficient may be adaptively adjusted according to the value of the filter coefficient calculated by the filter coefficient adjusting unit 130, which will be described later.

The filter coefficient adjustment unit 130 adaptively adjusts the filter coefficient value of the second low-pass filter of the low-pass filter unit 120 in accordance with the characteristics of the pulse wave SIGO. The filter coefficient adjustment unit 130 adjusts the cutoff frequency of the second low-pass filter by adjusting the filter coefficient according to the characteristics of the pulse wave SIG0 so that the pulse wave peak detection unit 140, which will be described later, So that the peak of the pulse wave SIG0 can be detected. The configuration and operation of the filter coefficient adjustment unit 130 and the low-pass filter unit 120 will be described in more detail with reference to FIGS. 3, 4A, 4B, 4C and 6.

The pulse wave peak detector 140 detects the highest point of the pulse wave SIG0 using the low frequency signal obtained by the low pass filter 120. [ At this time, the pulse-wave peak detector 140 preferably detects the peak of the low-frequency signal and detects the peak of the pulse wave SIG0 within a predetermined time interval from the peak of the detected low-frequency signal. As described above, by detecting the highest point of the low-frequency signal, it is possible to grasp the overall flow of the blood pressure excluding the high-frequency component of the pulse wave SIG0, and to grasp the approximate interval in which the peak of the pulse wave SIG0 occurs. By detecting the coordinates of the pulse wave SIG0 having the maximum magnitude value within a predetermined time interval from the highest point of the detected low frequency signal as above, the local peak that is likely to occur locally due to noise is not detected as the systolic blood pressure, It is possible to correctly detect the peak of the pulse wave SIG0 corresponding to the point of occurrence of the systolic blood pressure. The configuration and operation of the pulse wave peak detector 140 will be described in more detail with reference to FIGS. 5 and 6. FIG.

The periodic pulse wave detecting unit 150 detects the pulse wave SIG1 classified on a cycle basis using the peak information of the pulse wave SIG0 detected by the pulse wave peak detecting unit 140. [ For example, the periodic pulse wave detecting unit 150 detects one pulse wave of the pulse wave SIG1 based on the peak of the pulse wave SIG0 detected by the pulse wave peak detecting unit 140 .

3 is a block diagram illustrating a filter coefficient adjustment unit 130 according to an embodiment of the present invention. The filter coefficient adjustment unit 130 according to the present embodiment may include a heart rate calculation unit 131 and a filter coefficient calculation unit 132. [

The heart rate calculation unit 131 obtains a signal from which the linear trend is removed from the pulse wave signal, applies a window function to the obtained signal by removing the linear tendency, Converts the signal obtained by applying the window function into a signal in the frequency domain, and analyzes the signal in the converted frequency domain to calculate the average heart rate of the pulse wave for a predetermined time.

The linear tendency means that the signal has a fixed offset value or has a linear component such as a constant slope in a certain section. The removal of the linear tendency means that the linear component such as the offset included in the signal Is extracted and removed.

Here, applying the window function is a pre-processing step for performing frequency domain transformation. The window function is a function having a specific value only within a finite length section, and various kinds of window functions exist depending on the function type. Preferably, the Hanning Window Function may be a window function.

Here, it is preferable to apply Fast Fourier Transform (FFT) as a frequency domain transform method of the signal.

Here, in calculating the average heart rate of the pulse wave, the average heart rate may be a frequency value corresponding to a signal having the largest magnitude in the converted frequency domain signal.

The filter coefficient calculator 132 calculates the filter coefficient of the second low pass filter 120 so that the cutoff frequency of the second low pass filter of the low pass filter 120 is a predetermined multiple of the average heart rate calculated by the heart rate calculator 130. [ Is calculated. The filter coefficient adjusting unit 130 adjusts the filter coefficient value of the second low-pass filter of the low-pass filter unit 120 when the average heart rate value fluctuates according to the average heart rate, The cut-off frequency of the pass filter can be adjusted adaptively. Preferably, the filter coefficient calculator 132 calculates the filter coefficient value so that the second low-pass filter is a finite impulse response (FIR) low-pass filter having a cutoff frequency of 1.8 times the calculated average heart rate can do. As the blood pressure waveform progresses to the periphery, the harmonic component of the second order or less increases in the waveform, and the frequency component of the blood pressure waveform shifts as the heartbeat changes. Therefore, in order to minimize the error of the blood pressure waveform according to the position of the blood vessel and the change of the heartbeat, the filter coefficient calculating unit 132 calculates a value of 1.8 times the heart rate, which is a value immediately before the second harmonic component in the waveform, 2 cut-off frequency of the low-pass filter. However, the value of the cutoff frequency above can be modified as necessary. The filter coefficient calculating unit 132 adjusts the cutoff frequency of the second low-pass filter as described above, so that even if the waveform of the pulse wave SIG0 varies according to the heart rate, the second low- It is possible to obtain a sawtooth low frequency signal from which inflection points are removed.

4A is a reference view showing a frequency response characteristic of the second low-pass filter of the low-pass filter 120 according to an embodiment of the present invention. As shown in the drawing, the second low-pass filter increases the cutoff frequency value by a predetermined multiple as the heartbeat rate of the pulse wave SIG0 increases.

FIG. 4B is a reference diagram showing a comparison of pulse waveforms after the pulse wave of the peripheral blood vessels is filtered by the low-pass filter unit 120 according to an embodiment of the present invention. 4C is a reference diagram showing a comparison of the shape of the pulse wave after the pulse wave of the aortic blood vessel is filtered by the low-pass filter unit 120. FIG. As shown in the drawing, the pulse waves are filtered by the low-pass filter 120, and then become a sawtooth-shaped low-frequency signal in which inflection points are stably removed.

5 is a block diagram showing a pulse wave peak detector 140 according to an embodiment of the present invention. The pulse wave peak detector 140 according to the present embodiment may include a differential section 141, a zero crossing point detector 142 and a local peak detector 143.

The differentiating unit 141 differentiates the low-frequency signal obtained by the low-pass filter unit 120. [ As described above, the differentiating section 141 differentiates the low-frequency signal as described above, and can detect a peak position of the pulse wave SIG0, that is, a rough position of a point corresponding to the systolic blood pressure.

The zero crossing point detecting unit 142 detects the position of the zero crossing point of the non-divided signal at the differentiating unit 141. [ At this time, the position of the zero crossing point where the non-divided signal changes from a positive value to a negative value and becomes zero is the highest point of the low frequency signal.

The local maximum point detecting unit 143 detects the peak of the pulse wave SIG0 within a predetermined time interval based on the zero crossing point detected by the zero crossing point detecting unit 142. [ The local maximum point detector 143 compares the size information of the pulse wave SIG0 within a predetermined time interval with reference to the time point at which the zero crossing point occurs and determines the point having the largest value as the highest point of the pulse wave SIG0 . Preferably, the peak of the pulse wave SIG0 may be detected within a time interval of 100 ms before the zero crossing point. Here, the 100 ms search area is set in order to consider the effect of group delay due to the filtering of the signal through the low-pass filter, and the length of the search area may be changed if necessary.

The pulse wave peak detector 140 may also operate as an apparatus for detecting the lowest point of the pulse wave SIG0. On the same principle, when the zero pulse detector 142 detects that the non-divided signal changes from a negative value to a positive value Detecting the lowest point of the low frequency signal and detecting the lowest point of the pulse wave SIGO within a predetermined time interval based on the lowest point of the detected low frequency signal, The lowest point corresponding to the diastolic blood pressure of the subject can be detected. The pulse wave SIG1 can be detected on the basis of the same principle by using the lowest point detected as above instead of the highest point of the pulse wave SIG0 detected in the present invention.

6 is a reference view showing a process of detecting the highest point of the pulse wave SIG0 by the low-pass filter 120 and the pulse-wave peak detector 140 according to an embodiment of the present invention.

7 is a block diagram showing a pulse-wave unit calibration unit 200 according to an embodiment of the present invention. The pulse wave unit calibration unit 200 according to the present embodiment may include a blood pressure measuring unit 210, a pulse wave specifying unit 220, and a unit calibration unit 230.

The blood pressure measuring unit 210 measures the blood pressure information including the blood pressure of the specific part of the body and the blood pressure measurement time point information. At this time, the blood pressure measuring unit 210 preferably measures the blood pressure of the brachial artery of the body. The configuration and operation of the blood pressure measuring unit 210 will be described in more detail with reference to FIG.

The pulse-wave specifying unit 220 receives the pulse wave SIG1 detected by the pulse-wave detecting unit 100 on a cycle-by-cycle basis, receives the measured blood pressure information from the blood-pressure measuring unit 210, Detects a starting point for each cycle, specifies one pulse of the pulse wave SIG1 generated after a certain period of time at the time of measuring the blood pressure, and specifies the cycle of the pulse wave SIG1 corresponding to the blood pressure measurement point in time.

Here, the pulse-wave specifying unit 220 may detect the starting point of each cycle of the input pulse wave SIG1 using an intersecting tangent method. The Intersecting Tangent Method is a method used to detect the starting point of a pulse wave. This method first sets a certain ratio of the pulse wave size to the threshold, and in the lower range, the pulse wave changes from a negative slope to a positive slope A tangent line is formed around the first differential peak point of each pulse wave when the detected lowest points exist within a predetermined time unit from each other and a horizontal line connecting the lowest point of each detected pulse wave is made, And the horizontal line is determined as the starting point of each cycle of the pulse wave.

Here, it is preferable that the pulse-wave specifying unit 220 specifies a pulse wave of one cycle occurring after a certain period of time at the time of measurement of the blood pressure among the input pulse-wave SIG1, wherein the predetermined period is one cycle, It is desirable to specify the pulse wave of the first cycle occurring after the measured point.

The unit calibration unit 230 calibrates the unit of the 1-cycle pulse wave specified by the pulse-wave specifying unit 220 on the basis of the blood pressure measured by the blood pressure measuring unit 210 and outputs the calibrated 1-cycle pulse wave The unit of the pulse wave of the remaining cycles is calibrated on the basis of the pulse wave signal, and the blood pressure unit obtains the calibrated pulse wave signal SIG2.

As described above, the pulse-wave unit calibration unit 200 according to an embodiment of the present invention specifies the pulse wave of the first cycle, which is the closest after the measurement time of the brachial artery blood pressure, among the detected pulse waves SIG1 , The unit is calibrated with the measured blood pressure, and the pulse waves of the subsequent periods are also calibrated on the basis of the pulse wave of the first period specified. Therefore, even if the heartbeat changes irregularly after the measurement point of the blood pressure, Can be calibrated to have the correct unit value. The conventional apparatus calibrates the unit by superimposing the waveform of the pulse wave over a predetermined time to derive the averaged waveform and then substituting the measured blood pressure into the waveform of the averaged pulse wave to correct the unit, In the case of a fibrillation patient, since the averaged blood pressure waveform in the steady state assumed by the existing blood pressure waveform detecting apparatus is difficult to be displayed, the blood pressure unit can not be correctly calibrated by the existing apparatus. However, the pulse-wave unit calibration unit 200 according to an embodiment of the present invention calibrates the blood pressure unit of the pulse wave with reference to the pulse wave of the first cycle that occurred nearest to the measured blood pressure, so that the blood pressure unit is robustly detected even in the case of irregular pulse. Can be calibrated. The improvement effect of the pulse-wave unit calibrator 200 according to the present invention when compared with the conventional apparatus can be confirmed by reference numerals of FIGS. 8A, 8B, 8C, 8D and 8E.

8A is a reference diagram showing a pulse wave of a peripheral blood vessel in a normal state.

FIG. 8B is a reference diagram showing a waveform in which pulse waves of peripheral blood vessels in a steady state of several cycles are superimposed. FIG.

8C is a reference diagram showing a pulse wave of a peripheral blood vessel in an atrial fibrillation patient having irregular heartbeat.

FIG. 8D shows waveforms of the peripheral blood vessels of FIG. 8C that are simply superimposed on the waveforms of the peripheral blood vessels of FIG. 8C, and waveforms of the averaged peripheral blood vessels when the waveforms are averaged (bold gray lines) And an average (blue line) of systolic blood pressure values at each cycle.

FIG. 8E is a graph showing a relationship between a pulse wave of a first period (a thick gray line) and a systolic blood pressure value of a pulse wave of the first period ) As a reference.

When the blood pressure unit is calibrated using an existing apparatus for irregular pulse waves of an image fibrillation patient, the starting point is not correctly detected and the blood pressure unit is not calibrated as shown in FIG. 8D, but the pulse wave unit calibration unit 200 according to the present invention It can be confirmed that the starting point of the pulse wave is correctly detected and the blood pressure unit is calibrated as shown in FIG. 8E.

9 is a block diagram showing a blood pressure measuring unit 210 according to an embodiment of the present invention. The blood pressure measuring unit 210 according to the present embodiment may include a sensor unit 211, an amplification unit 212, a noise elimination filter unit 213, a blood pressure information calculation unit 214 and a sensor driving unit 215 .

The sensor unit 211 measures the blood pressure while pressing and loosening a specific part of the body. Preferably, the brachial artery pressure can be measured while the upper arm is squeezed under pressure and relaxed.

The amplification unit 212 amplifies the blood pressure signal measured by the sensor unit 211.

The noise removing filter unit 213 removes noise of the blood pressure signal amplified by the amplifying unit 212 through filtering.

The blood pressure information calculation unit 214 analyzes the blood pressure signal from which the noise is removed by the noise removing filter unit 213 and calculates the blood pressure information including the blood pressure and the blood pressure measurement time point information.

The sensor driving unit 215 drives the sensor unit 211 by adjusting the air pressure of the pressing pad provided on the sensor unit 211.

For example, when the blood pressure measuring unit 210 measures blood pressure in the brachial artery and sends information on the blood pressure and the measurement time to the pulse-wave specifying unit 220, the pulse-wave detecting unit 100 and the pulse- The pulse-wave specifying unit 220 may be configured such that the pulse wave SIG0 measured in the radial artery by the pulse-wave measuring unit 110 corresponds to the low-pass filter 120, the pulse-wave peak detecting unit 140, The pulse wave unit calibration unit 230 receives a pulse wave SIG1 detected as a cycle unit while being divided into a cycle unit and specifies one cycle of the first pulse wave generated after the time point of measurement of the blood pressure of the brachial artery, In the unit 220, the magnitude of the blood pressure of the specified one-period pulse wave is calibrated to the magnitude of the measured blood pressure of the brachial artery, and the blood pressure unit of the remaining pulse wave is the pulse wave of the one- It can operate in a manner of calibrating the unit according to the blood pressure.

According to the aortic blood pressure estimation apparatus of the present invention as described above, a low-pass filter adaptively changing the frequency response characteristics according to various pulse wave states is designed, and a low-frequency signal in which inflection points are removed is used And detects the peak of the pulse wave within a predetermined time interval by using the peak information of the low frequency signal. By detecting the peak of the pulse wave in the pulse wave of the atrial fibrillation patient having irregular heartbeat characteristic, The aortic blood pressure can be accurately estimated by detecting the pulse wave and adaptively estimating the aortic blood pressure according to the state of the pulse wave.

10 is a block diagram illustrating a method of estimating an aortic blood pressure according to another embodiment of the present invention. Each step of FIG. 10 is a process of operating the aortic blood pressure estimation apparatus according to the first embodiment of the present invention. Therefore, the parts of the aortic blood pressure estimation device which overlap with those described above in the process of the above-described FIGS. 1 to 9 will be briefly described. The aortic blood pressure estimation method according to the present embodiment includes a pulse wave detection step S1, a pulse wave unit correction step S2, a blood pressure waveform information acquisition step S3, a prediction filter coefficient calculation step S4, Step S5. Hereinafter, each step constituting the aortic blood pressure estimation method will be described in more detail.

In the pulse wave detecting step S1, the pulse wave SIG0 of the body blood vessel is measured, and the pulse wave SIG1 divided by the period unit is detected. The concrete operation of step S1 will be described in more detail with reference to FIG.

In the pulse wave unit calibration step S2, blood pressure information including blood pressure and blood pressure measurement time point information is measured at a specific part of the body, and the unit of the detected pulse wave SIG1 is calibrated based on the blood pressure information, And obtains the pulse wave signal SIG2 whose blood pressure unit is calibrated. The concrete operation of step S2 will be described in more detail with reference to FIG.

In the blood pressure waveform information acquisition step S3, blood pressure waveform information including the diastolic blood pressure and pulse wave period information is obtained by measuring the pulse waveform of the body and analyzing the pulse wave signal SIG2, which is a signal obtained by calibrating the blood pressure unit.

In the prediction filter coefficient calculation step S4, a filter coefficient of a prediction filter capable of variably controlling the filter coefficient is calculated based on the diastolic blood pressure and the pulse wave period information in the blood pressure waveform information. Here, the predictive filter coefficient calculating step S4 may calculate the filter coefficient of the prediction filter based on the diastolic blood pressure and the pulse wave period in the blood pressure waveform information calculated from the pulse wave signal SIG2, It is preferable that the cut-off frequency of the first low-pass filter is determined according to Equation (3), and the filter coefficient is calculated so that the prediction filter becomes the first low-pass filter having the determined cut-off frequency value.

(Where CF is a cut-off frequency of the prediction filter, a, b and c are constants having constant values, L is the pulse wave period, and DBP is the diastolic blood pressure).

Here, the value of a is 1.477 to 2.831, the value of b is 0.001 to 0.002, and the value of c is preferably in the range of 0.004 to 0.018. Further, a is 2.188, b is 0.001, and c is 0.011 .

In the prediction filter filtering and the aortic blood pressure estimation step S5, the pulse wave signal SIG2 is filtered by the prediction filter having the calculated filter coefficient, and the aortic blood pressure is estimated by analyzing the filtered signal.

11 is a detailed flowchart of a pulse wave detecting step S1 of the aortic blood pressure estimation method according to an embodiment of the present invention. The pulse wave detecting step S1 according to the present embodiment includes a pulse wave measuring step S11, a filter coefficient adjusting step S12, a low pass filter filtering step S13, a pulse wave peak detecting step S14, S15).

In the pulse wave measuring step S11, the blood pressure of the body blood vessel is measured to acquire the pulse wave SIG0. At this time, it is preferable to measure the pulse wave of the radial artery above the wrist using a high-precision torque meter.

In the filter coefficient adjustment step S12, the frequency domain signal of the pulse wave SIG is analyzed to calculate an average heart rate for a predetermined time. In step S13, the cutoff frequency of the second low-pass filter is calculated based on the calculated average heart rate The filter coefficient is adaptively adjusted so as to have a certain multiple of the value of the filter coefficient. At this time, in step S2, a linear trend, which is a linear component having a constant slope, is removed from the signal of the pulse wave SIG0, and then the signal is converted into a frequency domain signal. The converted frequency domain signal is analyzed, Calculating a mean heart rate of a pulse wave and calculating a filter coefficient value of a second low-pass filter such that a cut-off frequency of the second low-pass filter is a predetermined multiple of the calculated average heart rate, The filter coefficient value can be adjusted adaptively. Preferably, the window function is a Hanning Window function, and the cutoff frequency is 1.8 times the measured average heart rate.

In the low-pass filter filtering step S13, the low-frequency signal is obtained by filtering the pulse wave SIG0 with the second low-pass filter having the filter coefficient calculated in the filter coefficient adjusting step S12.

In the pulse wave peak detection step S14, the highest point of the pulse wave SIG0 is detected using the low-frequency signal obtained in the low-pass filter filtering step S13. At this time, in step S14, the low-frequency signal is differentiated, the position of the zero crossing point of the non-divided signal is detected to detect the highest point of the obtained low-frequency signal, (SIG0) can be detected. At this time, it is preferable that the predetermined time interval for finding the peak of the pulse wave is within 100 ms from the zero crossing point.

In the cycle unit pulse wave detecting step S15, the pulse wave SIG1 is detected using the peak information of the detected pulse wave SIG0.

12 is a detailed flowchart of the pulse wave unit calibration step S2 of the aortic blood pressure estimation method according to the embodiment of the present invention. The pulse wave unit calibration step S2 according to the present embodiment may include a blood pressure measurement step S21, a pulse wave identification step S22, and a unit calibration step S23.

In the blood pressure measuring step S21, the blood pressure information including the blood pressure of the specific part of the body and the blood pressure measurement time point information is measured. At this time, in step S21, the blood pressure is measured while pressing and loosening a specific part of the body, the amplified blood pressure signal is amplified, the noise of the amplified blood pressure signal is removed through filtering, and the noise- And the blood pressure information including the blood pressure and the blood pressure measurement time point information can be measured. At this time, it is preferable that the specific part of the body for measuring the blood pressure information is the upper arm.

In the pulse-wave specifying step S22, the pulse wave of one cycle, which occurs after a certain period of time from the pulse-wave measuring time point of the pulse-wave SIG1 detected by the cycle unit, is specified. Here, it is preferable to specify a pulse wave of one cycle occurring after one cycle at the time of measuring the blood pressure.

In the unit calibration step S23, the specified unit of the pulse wave of one cycle is calibrated based on the measured blood pressure, the unit of the pulse wave of the remaining cycles is calibrated on the basis of the calibrated pulse wave of one period, And acquires the pulse wave signal SIG2 in which the blood pressure unit is calibrated.

In yet another embodiment of the present invention, the blood pressure waveform information acquisition step (S3), the prediction filter coefficient calculation step (S4), the blood pressure waveform information calculation step (S4) Prediction filter filtering and the aortic blood pressure estimation step S5. At this time, the blood pressure waveform information calculating step (S3) can measure the pulse waveform of the body and input the pulse wave signal which is a signal obtained by calibrating the blood pressure unit.

는 선형회귀식의 성능을 말해주는 지표로 1에 가까울수록 실제 측정된 값과 추정된 대동맥혈압 간에 높은 선형성이 있음을 의미하며,

는 이러한 선형성이 부정될 확률을 뜻하며 0.05 이하인 경우 통계적으로 의미가 있는 결과라고 간주된다.FIG. 13 is a reference diagram showing a result of estimating aortic blood pressure of actual atrial fibrillation patients using an aortic blood pressure estimation apparatus according to an embodiment of the present invention. In the experiment, the peripheral blood pressure and the aortic blood pressure of 15 patients with atrial fibrillation were measured, and the aortic blood pressure of each atrial fibrillation patient was estimated from the peripheral blood pressure measured using the aortic blood pressure estimating apparatus according to an embodiment of the present invention The estimated aortic blood pressure was compared with the actual measured aortic blood pressure. At this time, a in the equation (1) for calculating the cut-off frequency of the prediction filter in the predictive filter coefficient adjuster 400 is 2.188, b is 0.001, and c is 0.011. 13 shows that the estimated aortic blood pressure value and the actual measured aortic blood pressure value have a high correlation, so that the aortic blood pressure estimation device according to an embodiment of the present invention correctly estimates the aortic blood pressure of atrial fibrillation patients Show. 13

Is an indicator of the performance of the linear regression equation. The closer to 1, the higher the linearity between the actual measured value and the estimated aortic blood pressure,

Means the probability that this linearity is negated, and if it is less than 0.05, it is considered to be a statistically significant result.

It is to be understood that the present invention is not limited to these embodiments, and all elements constituting the embodiment of the present invention described above are described as being combined or operated in one operation. That is, within the scope of the present invention, all of the components may be selectively coupled to one or more of them.

In addition, although all of the components may be implemented as one independent hardware, some or all of the components may be selectively combined to perform a part or all of the functions in one or a plurality of hardware. As shown in FIG. In addition, such a computer program may be stored in a computer readable medium such as a USB memory, a CD disk, a flash memory, etc., and read and executed by a computer to implement an embodiment of the present invention. As the recording medium of the computer program, a magnetic recording medium, an optical recording medium, a carrier wave medium, and the like can be included.

Furthermore, all terms including technical or scientific terms have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs, unless otherwise defined in the Detailed Description. Commonly used terms, such as predefined terms, should be interpreted to be consistent with the contextual meanings of the related art, and are not to be construed as ideal or overly formal, unless expressly defined to the contrary.

It will be apparent to those skilled in the art that various modifications, substitutions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. will be. Therefore, the embodiments disclosed in the present invention and the accompanying drawings are intended to illustrate and not to limit the technical spirit of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments and the accompanying drawings . The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

100:
110:
120: Low pass filter section
130: Filter coefficient adjustment section
131: heart rate calculating unit
132: Filter coefficient calculation unit
140: pulse wave peak detection unit
141:
142: Zero crossing point detector
143: Local peak detector
150: Periodic pulse wave detector
200: pulse wave unit calibration unit
210: blood pressure measuring unit
211:
212:
213: Noise canceling filter section
214: blood pressure information calculation unit
215:
220:
230: pulse wave unit calibration unit
300: blood pressure waveform analysis unit
400: prediction filter coefficient adjustment section
500: prediction filter unit
SIG0: pulse wave measured by the pulse wave measuring part
SIG1: Pulse detected in a cycle unit
SIG2: a pulse wave signal whose blood pressure unit is calibrated

Claims (19)

In the aortic blood pressure estimation apparatus,
A blood pressure waveform analyzing unit that receives blood pressure signal and acquires blood pressure waveform information including diastolic blood pressure and pulse wave period information using the pulse wave signal;
A prediction filter unit having a prediction filter capable of variably controlling the filter coefficient, filtering the pulse wave signal with the prediction filter, and analyzing the filtered signal to estimate the aortic blood pressure; And
And a prediction filter coefficient adjustment unit for calculating a filter coefficient of the prediction filter of the prediction filter unit based on the blood pressure waveform information obtained by the blood pressure waveform analyzing unit and adaptively adjusting the filter coefficient of the prediction filter in accordance with the pulse wave signal The aortic blood pressure estimating device. The method according to claim 1,
Wherein the pulse wave signal is a signal obtained by measuring a waveform of a pulse of the body, detecting the waveform by dividing the waveform into period units, and calibrating a blood pressure unit of the waveform, wherein the systolic blood pressure and diastolic blood pressure information And pulse-wave-period information. The method according to claim 1,
Wherein the predictive filter coefficient adjuster calculates the filter coefficient of the predictive filter based on the diastolic blood pressure and the pulse wave period in the blood pressure waveform information calculated from the pulse wave signal. The method of claim 3,
Wherein the prediction filter coefficient adjustment unit determines a cutoff frequency of the first low pass filter according to the following equation 1 and calculates the filter coefficient so that the prediction filter becomes the first low pass filter having the determined cutoff frequency value Aortic Blood Pressure Estimator.
Equation 1.

(Where CF is a cut-off frequency of the prediction filter, a, b and c are constants having constant values, L is the pulse wave period, and DBP is the diastolic blood pressure). 5. The method of claim 4,
The a is 1.477 to 2.831, the b is 0.001 to 0.002, and the c is 0.004 to 0.018. The method according to claim 1,
Wherein the prediction filter unit sets the filter coefficient of the prediction filter according to the filter coefficient value calculated by the prediction filter coefficient adjustment unit, filters the pulse wave signal with the set prediction filter, analyzes the filtered signal, And estimates an aortic blood pressure. The method according to claim 1,
A pulse wave detecting unit for measuring a pulse wave of a body blood vessel, detecting a peak of the pulse wave, and detecting the pulse wave grouped in a cycle unit; And
A pulse wave detecting unit for detecting pulse waves divided in a cycle unit and receiving blood pressure information and measuring blood pressure information including blood pressure and blood pressure measurement time point information in a specific part of the body separately from the pulse wave; And a pulse-wave-unit calibrating unit for calibrating the pulse-wave unit separately and acquiring the pulse-wave signal,
Wherein the blood pressure waveform analyzer receives the pulse wave signal from the pulse wave unit calibration unit. The blood pressure monitor according to claim 7,
A pulse wave measuring unit for measuring a blood pressure of a blood vessel of a body, amplifying the pulse signal, and removing the noise of the amplified pulse signal to obtain the pulse wave;
A low-pass filter unit having a second low-pass filter capable of variably controlling a filter coefficient and filtering the pulse wave with the second low-pass filter to obtain a low-frequency signal;
A filter coefficient adjuster for adaptively adjusting a filter coefficient value of the second low-pass filter according to characteristics of the pulse wave;
A pulse wave peak detector for detecting a peak of the pulse wave using the low frequency signal obtained by the low pass filter; And
And a periodic unit pulse wave detecting unit for detecting the pulse wave divided on a cycle basis using the peak information of the pulse wave detected by the pulse wave peak detecting unit. The apparatus as claimed in claim 8,
A signal obtained by removing a linear trend, which is a linear component having a constant slope in the signal of the pulse wave, is obtained, and a window function, which is a function having a specific value in a section of a finite length to the obtained signal by removing the linear tendency, A window function is applied to obtain a signal limited to a predetermined length, a signal obtained by applying the window function is converted into a signal in a frequency domain, and the signal in the converted frequency domain is analyzed, A heart rate calculation unit for calculating an average heart rate of the subject; And
And a filter coefficient calculation unit for calculating a filter coefficient value of the second low-pass filter so that the cutoff frequency of the second low-pass filter is a predetermined multiple of the average heart rate calculated by the heart rate calculation unit,
Wherein the controller adjusts the filter coefficient value of the second low-pass filter according to the average heart rate when the average heart rate value fluctuates. 9. The blood pressure monitor according to claim 8,
A differential section for differentiating the low-frequency signal obtained by the low-pass filter section;
A zero crossing point detecting unit for detecting the zero crossing point of the differentiated signal in the differential unit; And
And a local maximum point detecting unit for detecting a maximum point of the pulse wave within a predetermined time interval based on the zero crossing point detected by the zero crossing point detecting unit,
And detects the highest point of the low frequency signal obtained by the low pass filter unit and detects the highest point of the pulse wave within a predetermined time period from the highest point of the detected low frequency signal. 8. The blood pressure monitor according to claim 7,
A blood pressure measuring unit for measuring the blood pressure information including a blood pressure of a specific part of the body and blood pressure measurement time point information;
A pulse wave detector for detecting a pulse wave, a pulse wave detector for detecting a pulse wave, a pulse wave detector for detecting a pulse wave, a pulse wave detector for detecting a pulse wave, A pulse-wave specifying unit that specifies the pulse wave of one cycle and specifies the cycle of the pulse wave corresponding to the blood pressure measurement time; And
A unit for correcting the pulse wave unit of one period specified by the pulse wave specifying unit on the basis of the blood pressure measured by the blood pressure measuring unit and correcting the unit of the pulse wave of the remaining cycles based on the corrected pulse wave of one cycle And a unit calibration section for measuring the blood pressure of the aorta. 12. The blood pressure monitor according to claim 11,
A sensor unit for measuring a blood pressure while pressing and relaxing a specific part of the body;
A sensor driver for driving the sensor unit;
An amplifying unit for amplifying the blood pressure signal measured by the sensor unit;
A noise removal filter unit for removing noise of the blood pressure signal amplified by the amplification unit through filtering; And
And a blood pressure information calculation unit for analyzing the blood pressure signal from which noise has been removed from the noise canceling filter unit and calculating the blood pressure information including the blood pressure and the blood pressure measurement time point information. 12. The method of claim 11,
The pulse-wave specifying unit makes a tangent line around the highest point of the first-order differential signal of the pulse wave, creates a horizontal line connecting the lowest points of the pulse wave, and determines an intersection of the tangent line and the horizontal line as a starting point of each cycle of the pulse wave Wherein the starting point of each pulse of the pulse wave is detected using an intersecting tangent method. In the aortic blood pressure estimation method,
The blood pressure waveform information including the diastolic blood pressure and the pulse wave period information is analyzed by analyzing the pulse wave signal which is obtained by measuring the waveform of the pulse of the body, Obtaining;
Calculating a filter coefficient of a prediction filter capable of variably controlling a filter coefficient based on the diastolic blood pressure and the pulse wave period information among the blood pressure waveform information; And
And estimating the aortic blood pressure by filtering the pulse wave signal with the predictive filter having the calculated filter coefficient and analyzing the filtered signal. The method of claim 14, wherein the calculating the filter coefficient of the prediction filter comprises:
Wherein the cutoff frequency of the first low-pass filter is determined according to the following equation (2), and the filter coefficient is calculated so that the prediction filter becomes the first low-pass filter having the determined cutoff frequency value.
Equation 2.

(Where CF is a cut-off frequency of the prediction filter, a, b and c are constants having constant values, L is the pulse wave period, and DBP is the diastolic blood pressure). 16. The method of claim 15,
Wherein the value of a is 1.477 to 2.831, the value of b is 0.001 to 0.002, and the value of c is 0.004 to 0.018. 15. The method of claim 14,
Measuring a pulse wave of a body vessel and detecting the pulse wave classified by a cycle unit; And
The blood pressure information including the blood pressure and the blood pressure measurement time point information is measured at a specific part of the body, the unit of the pulse wave detected by the periodic unit is calibrated based on the blood pressure information, The method further comprising the step of: acquiring the aortic blood pressure. 18. The method of claim 17, wherein the step of detecting the pulse wave,
Measuring a blood pressure of a body vessel to obtain the pulse wave;
A linear function, which is a linear component having a constant slope, is removed from the signal of the pulse wave, and a window function, which is a function having a specific value in a section of a finite length, is applied to the signal obtained by removing the linear tendency A signal obtained by applying the window function is converted into a frequency domain signal, and the average heart rate of the pulse wave for a predetermined time is calculated by analyzing the converted frequency domain signal And a filter coefficient value of a second low-pass filter which calculates the cut-off frequency of the second low-pass filter to be a predetermined multiple of the average heart rate calculated by the heart rate calculation unit. When the average heart rate is changed, Adjusting the filter coefficient value to a predetermined value;
Filtering the pulse wave with the second low-pass filter having the calculated filter coefficient to obtain a low-frequency signal;
And a second low pass filter for differentiating the signal filtered by the second low pass filter to detect the position of the zero crossing point of the differentiated signal and detecting the highest point of the obtained low frequency signal, Detecting a peak of the pulse wave at a predetermined time interval from a peak of the detected low frequency signal; And
And detecting the pulse wave divided on a cycle basis using the detected peak information of the pulse wave. 18. The method of claim 17, wherein obtaining the calibrated pulse wave signal comprises:
Measuring blood pressure information including a blood pressure of a specific part of the body and blood pressure measurement time point information;
Identifying the pulse wave of one cycle occurring after a predetermined period at the time of measuring the blood pressure among the pulse waves detected by the cycle unit; And
Calibrating a unit of the specified one cycle of the pulse wave with reference to the measured blood pressure and calibrating a unit of the pulse wave of the remaining cycles based on the corrected one cycle of the pulse wave to obtain the pulse wave signal The aortic blood pressure estimation method < RTI ID = 0.0 >

Images