JP2001137203A - Blood pressure monitoring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently determine the correspondence between the estimated blood pressure value of a living body and pulse wave propagation speed information with sufficient accuracy by means of a blood pressure monitoring device, determining the estimated blood pressure value on the basis of the information about the propagation speed of a pulse wave propagating through the artery of the living body. SOLUTION: The U-time of each of peripheral pulse waves detected one after another by a photoelectric pulse wave sensor 40 is determined by an artery hardness information determining means 56.. The U-time actually determined by the artery hardness information determining means 56 is substituted into a predetermined secondary relational expression by an inclination determining means 60 so as to determine the inclination a of a linear relational expression between the estimated blood pressure value EBP and the pulse wave propagation time DT. A section β of the linear relational expression which determines the inclination αis determined by a slice determining means 62 from the blood pressure value BP measured by the blood pressure measuring means 50 and the pulse wave propagation time DT determined while the blood pressure measuring means 50 measures blood pressure. Thus, the correspondence between the estimated blood pressure value EBP and the pulse wave propagation time DT can be accurately determined by a single blood pressure measurement made by the blood pressure measuring means 50.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blood pressure monitoring device for monitoring a blood pressure of a living body based on pulse wave propagation speed information relating to a propagation speed of a pulse wave propagating in an artery of the living body.

[0002]

As pulse wave velocity information of the pulse wave propagating in the arteries of the Prior Art The biological, propagation time for the pulse wave between two predetermined sites propagate DT (sec) and the propagation velocity V _M (m / s It is known that such pulse wave propagation velocity information has a substantially proportional relationship with the blood pressure value BP (mmHg) of the living body within a predetermined range. Then, from the blood pressure value BP of the living body measured in advance and the pulse wave propagation velocity information, for example, EBP = α
(DT) + β (α is a negative value) or EBP = α
(V _M ) + β (where α is a positive value) coefficients α and β in a relational expression expressed in advance are determined, and pulse wave propagation velocity information actually sequentially determined using the relational expression is determined. There is proposed a blood pressure monitoring device that monitors an organism's blood pressure value by calculating an estimated blood pressure value EBP based on the EBP.

[0003]

By the way, in determining the correspondence between the estimated blood pressure value EBP and the pulse wave velocity information, at least two sets of blood pressure values BP and pulse wave velocity information of the living body are required. However, in order to accurately determine the relationship, it is desirable that the blood pressure values of the two living bodies be values that are as far apart as possible. However, in the related art, since the blood pressure measurement by the second cuff is performed irrespective of the actual blood pressure of the living body, the correspondence cannot always be determined with sufficient accuracy. In addition, the above 2
It is conceivable to repeatedly execute the blood pressure measurement using the cuff until a measurement value sufficiently separated between the blood pressure values of the two living bodies is obtained. It takes time,
There is a disadvantage that an unnecessary burden is imposed on the living body.

The relationship between the blood pressure value of the living body and the pulse wave propagation velocity information shows a high correlation in a short time.
If a correlation is obtained over a long period of time, the correlation is reduced. Therefore, in order to maintain a high correlation, a reliable blood pressure value is frequently measured using a cuff, and the estimated blood pressure value EBP is calculated from the blood pressure value and the pulse wave propagation velocity information at the time of measuring the blood pressure. Frequently, the coefficients of the relevant relations need to be re-determined, and cuff compression is a burden on the patient.

The present invention has been made in view of the above circumstances, and has as its object to estimate the blood pressure of a living body based on pulse wave propagation velocity information of a pulse wave propagating in an artery of the living body. In a blood pressure monitoring device that determines a value, a correspondence between an estimated blood pressure value and pulse wave propagation velocity information can be efficiently determined with sufficient accuracy, and a high blood pressure estimation accuracy without imposing a burden on a patient. Is to be able to maintain.

[0006]

Means for Solving the Problems The present inventor has made the following findings while conducting various studies on the background described above. That is, the blood pressure value of the living body is affected by the hardness of the artery, the blood pressure increases as the artery becomes harder, and the hardness of the artery changes in a short time due to the state of the autonomic nerve and the like. Is known. Therefore, it is considered that the coefficient of the relational expression for calculating the estimated blood pressure value can also be determined based on the information representing the hardness of the artery, and based on the pulse wave from the rising point to the peak of the pulse wave propagating in the living body. When the slope of the relational expression for calculating the estimated blood pressure value was determined using the arterial stiffness information that could be determined, it was found that the estimated blood pressure value could be determined with high accuracy. The present invention has been made based on such findings.

[0007]

A first aspect of the present invention for solving the above-mentioned problems is that the blood pressure of the living body is changed by using a cuff for changing a pressure applied to a part of the living body. A blood pressure measuring means for measuring the value of the blood pressure, and the biological information based on the pulse wave propagation velocity information of the actual living body from a preset linear relationship between the blood pressure value by the blood pressure measuring means and the pulse wave propagation velocity information of the living body. An estimated blood pressure value determining means for sequentially determining the estimated blood pressure value, and based on the estimated blood pressure value determined by the estimated blood pressure value determining means, a blood pressure monitoring device that monitors the blood pressure of the living body, a) a pulse wave detecting device for sequentially detecting a pulse wave propagating in the living body, and (b) a pulse wave detecting device for sequentially detecting the pulse wave from the rising point to the peak of the pulse wave sequentially detected by the pulse wave detecting device. Arterial stiffness in relation to arterial stiffness Arterial stiffness information determining means for determining information, (c) using a quadratic relational expression between the predetermined arterial stiffness information and the slope of the straight line, the arterial stiffness information determining means actually Inclination determining means for determining the inclination of the straight line based on the determined arterial stiffness information of the living body,
(d) From the blood pressure value measured by the blood pressure measurement unit and the pulse wave propagation velocity information determined at the time of measuring the blood pressure by the blood pressure measurement unit, determine the intercept of the straight line whose inclination is determined by the inclination determination unit. Intercept determining means.

[0008]

In this way, the arterial stiffness information determining means determines the arterial stiffness information based on the pulse wave from the rising point to the peak of the pulse wave sequentially detected by the pulse wave detecting device. The inclination determining means determines the inclination of the straight line using a predetermined quadratic relational expression based on the arterial hardness information actually determined by the arterial hardness information determining means, and determines the intercept determining means. In, the intercept of the straight line whose slope is determined is determined from the blood pressure value measured by the blood pressure measuring means and the pulse wave propagation velocity information determined at the time of measuring the blood pressure by the blood pressure measuring means. Therefore, the correspondence between the estimated blood pressure value and the pulse wave propagation velocity information can be determined with high accuracy by only one blood pressure measurement by the blood pressure measurement means.

[0009]

A second aspect of the present invention for solving the above-mentioned problems is that the blood pressure of the living body is changed by using a cuff for changing a pressure applied to a part of the living body. A blood pressure measuring means for measuring the value of the blood pressure, and the biological information based on the pulse wave propagation velocity information of the actual living body from a preset linear relationship between the blood pressure value by the blood pressure measuring means and the pulse wave propagation velocity information of the living body. An estimated blood pressure value determining means for sequentially determining the estimated blood pressure value, and based on the estimated blood pressure value determined by the estimated blood pressure value determining means, a blood pressure monitoring device that monitors the blood pressure of the living body, a) a pulse wave detecting device for sequentially detecting a pulse wave propagating in the living body, and (b) a pulse wave detecting device for sequentially detecting the pulse wave from the rising point to the peak of the pulse wave sequentially detected by the pulse wave detecting device. Arterial Stiffness Information Related to Arterial Stiffness in Children Arterial stiffness information determining means to be sequentially determined, and (c) sequentially determined by the arterial stiffness information determining means using a quadratic relational expression between the predetermined arterial stiffness information and the slope of the straight line. Inclination updating means for sequentially updating the inclination of the preset straight line based on the arterial hardness information of the living body.

[0010]

In this way, the arterial stiffness information determining means sequentially converts the arterial stiffness information based on the pulse wave from the rising point to the peak of the pulse wave sequentially detected by the pulse wave detecting device. Determined, based on the arterial stiffness information sequentially determined by the arterial stiffness information determining means by the slope updating means, the slope of a straight line set in advance to calculate the estimated blood pressure value is sequentially updated, High blood pressure estimation accuracy can be maintained.

[0011]

Here, preferably, the blood pressure monitoring device further includes a tilt display means for displaying a tilt determined by using the quadratic relational expression on a display. With this configuration, the gradient in the linear relationship between the estimated blood pressure value and the pulse wave velocity information serves as an index of arterial hardness, and thus the arterial hardness is determined from the gradient displayed on the display. be able to.

[0012]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a block diagram illustrating a configuration of a blood pressure monitoring device 8 to which the present invention has been applied.

In FIG. 1, a blood pressure monitoring device 8 includes a cuff 10 having a rubber bag in a cloth band-shaped bag and wound around a patient's upper arm 12, for example, and a cuff 10 connected to the cuff 10 through a pipe 20. It has a pressure sensor 14, a switching valve 16, and an air pump 18 connected thereto. This switching valve 16
Switches between three states: a pressure supply state in which the supply of pressure into the cuff 10 is permitted, a slow discharge state in which the cuff 10 is gradually discharged, and a rapid discharge state in which the cuff 10 is rapidly discharged. It is configured to be.

The pressure sensor 14 detects the pressure in the cuff 10 and outputs a pressure signal SP representing the pressure to the static pressure discriminating circuit 22.
And the pulse wave discrimination circuit 24. Static pressure filter circuit 22 includes a low pass filter, steady pressure or cuff pressure P _C to discriminate the cuff pressure signal SK representative of the in the cuff pressure signal SK to the A / D converter 2 is included in the pressure signal SP
6 to the electronic control unit 28.

The pulse wave discrimination circuit 24 includes a band pass filter, and a pulse wave signal SM which is a vibration component of the pressure signal SP.
₁ is discriminated in frequency and the pulse wave signal SM ₁ is supplied to the electronic control unit 28 via the A / D converter 29. The cuff pulse wave represented by the pulse wave signal SM ₁ is a pressure vibration wave, that is, a cuff pulse wave generated from a brachial artery (not shown) and transmitted to the cuff 10 in synchronization with the heartbeat of the patient. 14 and the pulse wave discrimination circuit 24 function as a cuff pulse wave sensor.

The electronic control unit 28 includes a CPU 30, R
The microcomputer 30 includes a so-called microcomputer having an OM 32, a RAM 34, an I / O port (not shown), and the like. The CPU 30 executes signal processing using a storage function of the RAM 34 according to a program stored in the ROM 32 in advance. Thus, a drive signal is output from the I / O port to control the switching valve 16 and the air pump 18 and to control the display contents of the display 36.

The electrocardiograph 38 continuously detects an electrocardiogram, which is a so-called electrocardiogram, showing an action potential of the myocardium through a plurality of electrodes 39 attached to a predetermined portion of a living body. A signal SM ₂ indicating an electrocardiographic wave is supplied to the electronic control unit 28. It should be noted that the electrocardiographic guiding device 38
Is for detecting the Q wave or the R wave of the electrocardiographic induction wave corresponding to the time when the blood in the heart starts to be pumped toward the aorta, and thus functions as the first pulse wave detection device. are doing.

The photoelectric pulse wave sensor 40 functions as a second pulse wave detecting device or a pulse wave detecting device for non-invasively detecting a pulse wave transmitted to a peripheral arteriole including a capillary blood vessel. It is configured in the same manner as that used for the like, and is attached to a part of the living body (for example, the fingertip on the side where the cuff 10 is not wound). The housing 42 is configured to accommodate a part of a living body. The housing 42 has a red light or infrared light in a wavelength band that can be reflected by hemoglobin, preferably about 800 nm that is not affected by oxygen saturation. a light emitting element 44 is a light source for irradiating toward the wavelength the skin of a living body, and a light detecting element 46 for detecting the scattered light from the epidermis, the photoelectric pulse-wave signal SM ₃ corresponding to the blood volume in capillaries And supplies it to the electronic control unit 28 via the A / D converter 48. The photoelectric pulse-wave signal SM ₃ is a signal pulsates every one heartbeat, and corresponds to the amount or volume of blood hemoglobin in the capillaries in the epidermis.

FIG. 2 shows an electronic device in the blood pressure monitoring device 8.
Functional block for explaining a main part of the control function of control device 28
FIG. The blood pressure measurement means 50 includes a cuff pressure control means 52
For example, the pressure of the cuff 10 wound around the upper arm of a living body
The compression pressure is set to a predetermined target pressure value P. _cm(For example, 180mmHg
About 3mmHg / sec after rapidly increasing the pressure to about
During the slow pressure decay period in which the pressure is gradually decreased at the speed of
Pulse wave signal SM to be sampled₁ Changes in the amplitude of the pulse wave
Systolic blood pressure using a well-known oscillometric method
Value BP_SYS, Mean blood pressure value BP_MEAN, And diastolic blood pressure B
P_DIAEtc., and the determined systolic blood pressure value B
P_SYS, Mean blood pressure value BP_MEAN, And diastolic blood pressure BP
_DIAAre displayed on the display 36.

The pulse wave propagation velocity information calculating means 54 detects a photoelectric pulse sequentially detected by the photoelectric pulse wave sensor 40 from a predetermined portion which is generated in each cycle of the electrocardiogram guided by the electrocardiograph 38. There is provided a time difference calculating means for sequentially calculating a time difference (pulse wave propagation time) DT up to a predetermined portion generated in each cycle of the wave. For example, as shown in FIG. The R-wave is used as the predetermined part, and the tangent L at the maximum slope point a at the rise of the photoplethysmogram is used as the predetermined part generated in each cycle of the photoplethysmogram.
Using an intersection point b between ₁ and photoelectric pulse wave baseline (baseline) L _2, sequentially calculates the time from R-wave to the intersection point b as the pulse wave propagation time DT. Further, based on the time difference DT sequentially calculated by the time difference calculating means, the pulse wave propagation speed information calculating means 54 calculates the propagation speed V of the pulse wave propagating in the artery of the subject from the equation 1 stored in advance. Calculate _M (m / sec) sequentially. In Equation 1, L (m) is the distance from the left ventricle via the aorta to the site where the photoelectric pulse wave sensor 40 is mounted, and T _PEP (sec) is the aortic origin from the R wave of the electrocardiographic waveform. This is the pre-ejection period up to the rising point of the initial pulse waveform. The distance L and the pre-ejection period T _PEP are constants, and values obtained based on experiments in advance are used.

[0021] (Formula _{1) V M = L / (} DT-T PEP)

The arterial stiffness information determining means 56 is based on the pulse wave from the rising point to the peak of the photoelectric pulse wave (peripheral pulse wave) detected by the photoelectric pulse wave sensor 40, and determines the artery hardness related to the arterial hardness. The hardness information is sequentially determined. When the artery becomes stiff, the shape of the pulse wave propagating in the artery also changes, but in particular, the effect appears greatly from the rising point to the peak, so the pulse wave from the rising point to the peak shows Hardness information can be determined.
As shown in FIG. 4, the photoplethysmogram is composed of a series of points that are sequentially input every several millimeters or several tens of millimeters, so that the arterial hardness information includes, for example, the following: Is used. That is, the rising point c and the peak d are determined by comparing sequentially input signals, and the U-time is calculated as a period during which the pulse wave from the rising point c to the peak d rises.
(msec), or a point at which the rate of increase is maximum from the rising point c to the peak d, that is, the slope γ of the tangent at the maximum slope point a, or, or, the first half hour from the rising point c to the maximum slope point a, or The second half time from the maximum slope point a to the peak d, or the ratio of the first half time to the second half time can be used.

The correspondence determining means 58 calculates the expression 2 or 3
And in in that to predetermine the coefficients α and β in relation to the wave propagation time DT or propagation velocity V _M and the estimated blood pressure value EBP indicated, the inclination determination unit 60 for determining the slope α
And an intercept determining means 62 for determining the intercept β.

(Equation 2) EBP = α (DT) + β (where α is a negative constant and β is a positive constant)

(Equation 3) EBP = α (V _M ) + β (where α is a positive constant, β is a positive constant)

The inclination determining means 60 is actually determined for each living body by the arterial stiffness information determining means 56 when the blood pressure is measured by the blood pressure measuring means 50 (that is, immediately before, during, or immediately after the blood pressure measurement). Based on the obtained arterial stiffness information, the gradient α of Expression 2 or 3 is determined using a predetermined quadratic relational expression between the gradient α and the arterial stiffness information.

For example, the inclination determining means 60 uses the arterial hardness information determining means 56 as Ut as arterial hardness information.
When the “im” is measured, the U-time actually determined by the arterial stiffness information determining means 56 is added to the predetermined equation (4).
By substituting e, the coefficient α of Equation 2 or Equation 3 is determined. (Equation 4) α = e (U-time) ² + f (U-time) + g (e, f, g are predetermined constants) Here, the constants e, f, and g of Expression 4 are conventional values. A set determined by measuring two or more sets of the coefficient α determined by the above method, that is, the relationship between the blood pressure and the pulse wave propagation velocity information, and a set of U-time obtained when measuring the blood pressure. Is determined in advance based on the data of Also, constants e, f,
g is a pulse wave detecting device (the photoelectric pulse wave sensor 4 in this embodiment).
A different value determined in advance based on an experiment is used for each part where the pulse wave is detected according to 0). Incidentally, the above-mentioned multiple sets of data may be collected for each individual who actually monitors the blood pressure.
The constants e, f, and g for determining the slope α are determined as follows. Since there is almost no individual difference in the constants e, f, and g, a predetermined constant value is determined regardless of the patient. Even if used, sufficient accuracy can be obtained. e = -0.212, f = 8.8103, g = -999.84 r = 0.9939 (r is a correlation coefficient)

The intercept determining means 62 calculates the systolic blood pressure value BP _SYS measured by the blood pressure measuring means 50 and the pulse wave propagation time DT or the pulse wave propagation velocity V _M in each blood pressure measurement period, for example, the pulse wave in that period. based on the average value of the propagation time DT or propagation velocity V _M, formula 2 or 3
Is determined in advance. That is, the blood pressure measuring means 50
A pulse-wave propagation time DT or pulse-wave propagation velocity V _M in the systolic blood pressure BP _SYS and the respective blood pressure measurement period measured by, in Formula 2 or Formula 3 inclination α is determined by the tilt determining means 60 To determine the intercept β. In addition, instead of the systolic blood pressure value _BPSYS , the blood pressure measuring means 5
An average blood pressure value BP _MEAN or a diastolic blood pressure value BP _DIA measured by 0 may be used. In short, the selection is made based on whether the monitored (estimated) blood pressure value EBP is a systolic blood pressure value, an average blood pressure value, or a diastolic blood pressure value.

The estimated blood pressure value determining means 64, the blood pressure value of the living BP and pulse wave propagation time of the living DT or propagation velocity V _M
The correspondence between the (Formula 2 or Formula 3), the actual pulse wave propagation time DT or propagation velocity V _M estimated BP value EBP based on the living body successively calculated by the pulse wave propagation velocity information calculation means 54 between the Are sequentially determined, and the determined estimated blood pressure value EBP is trend-displayed on the display 36 as shown in FIG.

The blood pressure measurement activating means 66 activates the blood pressure measurement by the blood pressure measuring means 50 based on the fact that the estimated blood pressure value EBP determined by the estimated blood pressure value determining means 64 exceeds a predetermined reference value. . That is, the blood pressure measurement activation means 66 sets the estimated blood pressure value EBP determined by the estimated blood pressure value determination means 64 to a predetermined reference value, for example, a predetermined value based on the previous blood pressure measurement by the blood pressure measurement means 50 using the cuff. Alternatively, it also functions as an estimated blood pressure value abnormality determination unit that determines an abnormality based on a change by a predetermined ratio or more, and starts blood pressure measurement by the blood pressure measurement unit 50 when it is determined that the estimated blood pressure value EBP is abnormal.

FIG. 6 is a flowchart for explaining a main part of the control operation in the electronic control unit 28 of the blood pressure monitoring device 8. The estimated blood pressure value EBP is sequentially determined from the pulse wave propagation time DT using the above equation (2). An example in which the blood pressure is monitored by using the method will be described.

In FIG. 6, step SA1 (hereinafter referred to as step
Omit the steps. ) Counter and register not shown
Initial processing for clearing the pulse wave
In SA2 corresponding to the report calculation means 54, the R wave of the electrocardiographic waveform
Are sequentially detected by the photoelectric pulse wave sensor 40 from the point of occurrence of
L at the maximum slope point a of the photoelectric pulse wave₁And baseline L _Two
Difference from the point of occurrence of the intersection b with the pulse wave, ie, the pulse wave transit time
DT is calculated. Further, the following arterial hardness information determining means
In SA3 corresponding to 56, the rising point c of the photoelectric pulse wave
U-time from to is calculated.

Next, in SA4 and SA5 corresponding to the cuff pressure control means 52, the switching valve 16 is switched to the pressure supply state and the air pump 18 is driven, so that the cuff 10 is rapidly increased for blood pressure measurement. There together is started, the cuff pressure P _C is whether a preset target pressing pressure P _CM than about 180mmHg is determined.
If the determination in SA5 is negative, increasing the cuff pressure P _C by the SA2 below is repeatedly executed is continued.

However, the cuff pressure P_CThe above SA
If the judgment of 5 is affirmative, the blood pressure measuring means 50
In SA6, the blood pressure measurement algorithm is executed.
You. That is, the air pump 18 is stopped and the switching valve 1
6 is switched to the slow exhaust pressure state and the pressure in the cuff 10 is
Lower at a fixed speed of about 3 mmHg / sec.
As a result, the pulse wave signal obtained successively during this slow down process
SM₁ Based on the change in the amplitude of the pulse wave represented by
Oscillometric blood pressure determination algorithm
Tte systolic blood pressure BP_SYS, Mean blood pressure value BP_MEAN,and
Minimum blood pressure BP _DIAIs measured and the pulse wave interval
The pulse rate and the like are determined based on this. And that
The measured blood pressure value BP and pulse rate are displayed on the display 36.
Is displayed, and the switching valve 16 is switched to the rapid exhaust pressure state.
The pressure inside the cuff 10 is rapidly discharged.

Next, SA7 to SA8 corresponding to the correspondence relationship determining means 58 are executed. That is, in SA7 corresponding to the inclination determining means 60, the cuff 1
Average U-time of U-time calculated during 0 boosting period
The time _AV is calculated and its U-time _AV
Is substituted into the quadratic relational expression of the above equation 4, whereby the equation 2
Is calculated. Note that the constant e in Equation 4,
For f and g, predetermined constant values are used to determine the gradient α in Equation 2.

In SA8 corresponding to the intercept determination means 62, the blood pressure value BP (for example, systolic blood pressure value BP _SYS ) determined in SA5 is added to the equation 2 in which the inclination α is determined in SA7.
And the pulse wave transit time DT when the blood pressure value BP is measured
(For example, pulse wave transit time DT calculated in SA2
Of the equation 2 is calculated by substituting the average value DT _AV ) of the equation (2).

After the pulse wave transit time blood pressure correspondence is determined as described above, it is determined in SA9 whether the R wave of the electrocardiographic waveform and the photoelectric pulse wave have been input. This S
When the determination of A9 is denied, SA9 is repeatedly executed. When the determination is affirmed, in SA10 corresponding to the pulse wave propagation velocity information calculating means 54, the R wave of the newly input electrocardiographic waveform and The pulse wave propagation time DT for the photoelectric pulse wave is calculated in the same manner as in SA2.

Then, in SA11 corresponding to the estimated blood pressure value determining means 64, the pulse wave transit time DT obtained in SA10 is substituted into the pulse wave transit time blood pressure correspondence obtained in SA7 to SA8, that is, equation 2. Then, the estimated blood pressure value EBP (systolic blood pressure value EBP _SYS , average blood pressure value EBP _MEAN , or diastolic blood pressure value EBP _DIA ) is determined, and the estimated blood pressure value EBP for each beat is expressed in a trend format as shown in FIG. Is displayed on the display 36.

Next, at SA12 corresponding to the blood pressure measurement starting means 66, it is determined whether or not the estimated blood pressure value EBP calculated at SA11 has exceeded a predetermined reference value. If the determination of SA12 is denied,
At SA13, the time elapsed since the blood pressure was measured by the cuff 10 at SA6 is set to 1
It is determined whether a set cycle of about 5 to 20 minutes, that is, a calibration cycle has elapsed.

If the determination at SA13 is negative, the blood pressure monitoring routine of SA9 and below is repeatedly executed, and the estimated blood pressure value EBP is continuously determined for each beat.
In addition, the determined estimated blood pressure value EBP is displayed on the display 36 in a time-series trend display. However, this SA
If the determination in step 13 is affirmative, the cuff calibration routine of SA2 and below is executed again to determine the correspondence again.

If the determination at SA12 is affirmative, SA14 is executed and an abnormal display of the estimated blood pressure value EBP is displayed on the display 36, and then, after SA2 is repeated, the correspondence is re-determined. By being executed,
The blood pressure measurement by the cuff 10 is activated.

As described above, according to the present embodiment, the U-time of the peripheral pulse wave sequentially detected by the photoelectric pulse wave sensor 40 is determined by the arterial stiffness information determining means 56 (SA3), and the inclination is determined. In the means 60 (SA7), the U actually determined by the arterial stiffness information determining means 56 (SA3) is used.
−time is substituted into the predetermined quadratic relational expression of Expression 4, and the slope α of the linear relational expression (Expression 2) between the estimated blood pressure value EBP and the pulse wave transit time DT is determined. 6
2 (SA8), the blood pressure value BP measured by the blood pressure measurement unit 50 (SA6) and the blood pressure measurement unit 50 (SA
From the pulse wave transit time DT determined at the time of blood pressure measurement according to 6), the intercept β of Equation 2 in which the slope α is determined is determined.
Accordingly, the correspondence between the estimated blood pressure value EBP and the pulse wave transit time DT can be determined with high accuracy only by one blood pressure measurement by the blood pressure measurement means 50 (SA6).

Next, another embodiment of the present invention will be described. In the following embodiments, portions common to the above-described embodiments will be denoted by the same reference numerals and detailed description thereof will be omitted.

FIG. 7 is a functional block diagram for explaining a main part of the blood pressure monitoring apparatus according to the second embodiment of the present invention. In the blood pressure monitoring device of the present embodiment, the mechanism and circuit configuration of the device are common to those of the above-described embodiment of FIG. 1, but the control operation of the electronic control device 28 is different. Hereinafter, the differences will be described.

In FIG. 7, the correspondence determining means 70
Systolic blood pressure value BP _SYS measured by blood pressure measuring means 50
If, based on the pulse wave velocity information in the blood pressure within the measurement period, for example on the basis of the average value of the pulse wave propagation time DT or pulse-wave propagation velocity V _M in the blood pressure within the measurement period,
The coefficient of the previously set corresponding relational expression represented by the above expression 2 or 3 is determined. In this case, for example, when the relationship of Equation 2 is used, the coefficient determination method uses the systolic blood pressure value BP _SYS measured by the blood pressure measurement unit 50 and the pulse wave propagation time DT calculated during the blood pressure measurement period. As a set,
With the systolic blood pressure value BP _SYS and the pulse wave transit time DT obtained during the previous blood pressure measurement as another set, coefficients α and β are determined in advance so as to satisfy the relationship between the two sets. Note that, instead of the systolic blood pressure value BP _SYS , the average blood pressure value BP _MEAN or the diastolic blood pressure value BP measured by the blood pressure measuring means 50 is used.
_DIA may be used. In short, the selection is made based on whether the estimated blood pressure value EBP is a systolic blood pressure value, an average blood pressure value, or a diastolic blood pressure value.

The inclination updating means 72 is based on the arterial hardness information sequentially determined by the arterial hardness information determining means 56,
Using a predetermined quadratic relational expression between the inclination α and the arterial stiffness information, the inclination α of the expression 2 or 3 representing the correspondence between the estimated blood pressure value EBP and the pulse wave propagation velocity information is calculated. And update.

The inclination display means 74 sequentially displays the inclination α calculated by the inclination updating means 72 on the display 36. Since the slope α in Equation 2 or Equation 3 for calculating the estimated blood pressure value EBP is considered to be useful also as an index indicating arterial hardness, it is displayed to judge (diagnose) the degree of arterial hardness. The value of α is sequentially displayed on the unit 36.

FIG. 8 shows an electronic control unit 2 according to this embodiment.
8 is a flowchart for explaining a main part of the control operation of FIG.

In FIG. 8, first, in SB1 and SB2, the same processing as in SA1 and SA2 of the above-described embodiment is executed, and in SB3 and SB5, the same processing as in SA4 and SA6 in the above-described embodiment is executed. Thus, the blood pressure value BP is determined, and the pulse wave propagation time DT at the time of measuring the blood pressure is calculated.

SB corresponding to the following correspondence relation determining means 70
6, the pulse wave transit time DT determined in SB2 and the systolic blood pressure value BP _SYS determined in SB5 are set as a set, and the pulse wave transit time D determined in the previous blood pressure measurement is set.
T and the systolic blood pressure value BP _SYS are another set, and the coefficients α and β of the correspondence relationship (Equation 2) between the pulse wave transit time DT and the estimated blood pressure value EBP are determined.

When the pulse wave transit time blood pressure correspondence is determined as described above, it is determined in SB7 whether the R wave of the electrocardiographic waveform and the photoelectric pulse wave have been input. This S
If the determination of B7 is denied, SB7 is repeatedly executed. If the determination is affirmed, the arterial stiffness information determining means 56 is executed.
In step SB8, the U-time for the photoelectric pulse wave input in step SB7 is calculated.

At SB9 corresponding to the pulse wave propagation velocity information calculating means 54, the pulse wave propagation time DT for the R wave and the photoelectric pulse wave of the electrocardiographic waveform input at SB7 is calculated in the same manner as at SB2. .

SB10 corresponding to the following inclination updating means 72
Then, the coefficient α is calculated by substituting the U-time calculated in the above SB8 into the equation 4 in which the constants e, f, and g are determined in advance, and the coefficient α in the equation 2 is newly calculated. Is updated to the specified value. Further, at SB11 corresponding to the following inclination display means 74, the value of the inclination α calculated at SB10 is displayed on the display 36.

In subsequent SB12 to SB15, S12 in FIG.
By performing the same processing as A11 to SA14, the estimated blood pressure value EBP is determined and output based on Expression 2 in which the coefficient α is updated in SB11, and the blood pressure measurement unit 70 is determined based on the estimated blood pressure value EBP. It is determined whether or not to start the blood pressure measurement by the user.

As described above, according to the present embodiment, the arterial stiffness information determining means 56 (SB8) sequentially determines the U-time of the photoelectric pulse wave sequentially detected by the photoelectric pulse wave sensor 40, and determines the slope. By the updating means 72 (SB10),
Based on the U-time sequentially determined by the arterial stiffness information determining means 56 (SB8) and a predetermined quadratic relational expression (Equation 4) between the U-time and the slope α, the estimated blood pressure value EBP Is calculated, the gradient α of the preset straight line (Equation 2) is sequentially updated, so that high blood pressure estimation accuracy can be maintained.

According to the present embodiment, the inclination display means 7
4 (SB11), the gradient α determined using the quadratic relational expression (Expression 4) is displayed on the display 36. Since the inclination α is an index of the hardness of the artery, the hardness of the artery can be determined from the inclination α displayed on the display 36.

While the embodiment of the present invention has been described in detail with reference to the drawings, the present invention can be applied to other embodiments.

For example, in the above-described embodiment, the photoelectric pulse wave sensor 40 functions as a second pulse wave detecting device for calculating pulse wave propagation velocity information, and detects a pulse wave for determining arterial stiffness information. Although the device also functions as a pulse wave detecting device for detection, the second pulse wave detecting device and the pulse wave detecting device may be different devices. For example, as a pulse wave detection device for determining arterial stiffness information, a photoelectric pulse wave detection probe for an oximeter, an impedance pulse wave detection device for detecting a change in impedance through an electrode attached to a finger, a carotid artery, A pressure pulse wave detecting device that is pressed by the radial artery and detects its internal pressure, a pressure pulse wave detecting device that detects a change in pressure in a compression band attached to a predetermined portion of a living body (for example, an upper arm), and the like are used. You may be. Further, the various devices described above may be used as a second pulse wave detection device for calculating pulse wave propagation velocity information.

Further, in the above-described embodiment, the electrocardiographic lead device 38 for detecting the electrocardiographic lead waveform is used as the first pulse wave detecting device for calculating the pulse wave velocity information.
A heart sound microphone that is attached to the chest of the living body and detects a heart sound may be used as the first pulse wave detection device, or if it is attached to an upstream portion of the second pulse wave detection device,
Various devices exemplified as devices that can be used as the second pulse wave detection device may be used as the first pulse wave detection device.

Further, the inclination α determined based on Equation 4 by the inclination determining means 60 (SA7) of the first embodiment is similar to the inclination α determined based on Equation 4 in the second embodiment. ,
It may be displayed on the display 36.

In the second embodiment, FIG.
In the flowchart of the above, the slope α of the equation 2 for obtaining the estimated blood pressure value EBP is updated for each beat of the photoelectric pulse wave, but may be updated for every two or more beats.

The present invention can be modified in various other ways without departing from the gist thereof.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a circuit configuration of a blood pressure monitoring device according to an embodiment of the present invention.

FIG. 2 is a functional block diagram illustrating a main part of a control function of the electronic control device in the embodiment of FIG. 1;

FIG. 3 is a diagram illustrating a time difference DT obtained by a control operation of the electronic control device in the embodiment of FIG. 1;

4 is a diagram exemplarily showing arterial stiffness information determined by an arterial stiffness information determining unit 56 in FIG. 2;

FIG. 5 is an estimated blood pressure value E obtained in the embodiment of FIG. 1;
FIG. 7 is a diagram illustrating an example in which a BP is trend-displayed on a display.

FIG. 6 is a flowchart illustrating a main part of a control operation of the electronic control device in the embodiment of FIG. 1;

FIG. 7 is a functional block diagram illustrating a main part of a control function according to another embodiment of the present invention.

FIG. 8 is a flowchart illustrating a main part of a control operation of the electronic control device in the embodiment of FIG. 7;

[Explanation of symbols]

 8: blood pressure monitoring device 40: photoelectric pulse wave sensor (pulse wave detecting device) 50: blood pressure measuring means 56: arterial stiffness information determining means 60: slope determining means 62: intercept determining means 64: estimated blood pressure value determining means 72: slope Update means

Claims (2)

[Claims] 1. A blood pressure measuring means for measuring a blood pressure value of a living body using a cuff for changing a compression pressure on a part of the living body,
Estimation for sequentially determining an estimated blood pressure value of the living body based on actual pulse wave propagation speed information of the living body from a preset linear relationship between the blood pressure value by the blood pressure measuring means and the pulse wave propagation speed information of the living body. A blood pressure monitoring device that monitors blood pressure of the living body based on the estimated blood pressure value determined by the estimated blood pressure value determining device, wherein the pulse wave sequentially propagates through the living body. A pulse wave detecting device for detecting, and an artery for determining arterial stiffness information related to arterial stiffness of the living body based on a pulse wave from a rising point to a peak of the pulse wave sequentially detected by the pulse wave detecting device Hardness information determining means, using a quadratic relational expression between the predetermined arterial hardness information and the slope of the straight line, the arterial stiffness of the living body actually determined by the arterial hardness information determining means. Slope of the straight line based on the Slope determining means for determining, from the blood pressure value measured by the blood pressure measuring means, and the pulse wave propagation speed information determined at the time of blood pressure measurement by the blood pressure measuring means, a straight line whose slope is determined by the tilt determining means A slice determining means for determining a slice. 2. A blood pressure measuring means for measuring a blood pressure value of a living body using a cuff for changing a compression pressure on a part of the living body,
Estimation for sequentially determining an estimated blood pressure value of the living body based on actual pulse wave propagation speed information of the living body from a preset linear relationship between the blood pressure value by the blood pressure measuring means and the pulse wave propagation speed information of the living body. A blood pressure monitoring device that monitors blood pressure of the living body based on the estimated blood pressure value determined by the estimated blood pressure value determining device, wherein the pulse wave sequentially propagates through the living body. A pulse wave detecting device to be detected, and arterial stiffness information related to arterial stiffness of the living body is sequentially determined based on a pulse wave from a rising point to a peak of the pulse wave sequentially detected by the pulse wave detecting device. Arterial stiffness information determining means, and using a quadratic relational expression between predetermined arterial stiffness information and the slope of the straight line, the arterial stiffness of the living body sequentially determined by the arterial stiffness information determining means. Based on the information Blood pressure monitoring device, characterized in that the inclination updating means includes for sequentially updating the slope of the line is.