JPH09201342A - Pulse wave propagation speed measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pulse wave propagation speed measuring device in which high measuring precision is maintained regardless of the degree of arteriosclerosis in a subject person. SOLUTION: A maximum inclination line determining means 86 determines the maximum inclination line LKmax passing the maximum inclination point Kmax of heartbeat synchronous waves, and having an inclination of the maximum inclination point Kmax , and a base line determining means 88 determines a base line BL connecting the minimum point on the rising side of hearbeat synchronous waves and the minimum point on the falling side. A reference point determining means 90 determines an intersection P1 of the maximum inclination line LKmax with the base line BL as a reference point TS to measure pulse wave propagation speed. The reference point TS without having effects of reflection waves in pulse waves can thus be determined, so irregularity is not generated for a set position of the reference point TS even for a subject person of arteriosclerosis in an advanced stage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulse wave velocity measuring device for measuring the velocity of a pulse wave propagating in an artery of a living body.

[0002]

2. Description of the Related Art For example, in order to estimate arteriosclerosis, blood pressure value, peripheral resistance of a living body, the propagation speed of a pulse wave propagating in an artery of the living body is obtained. As one of the methods, for example, a pulse wave sensor that presses an artery from the skin of a living body to detect a pulse wave generated from the artery is provided at two locations, and based on the pulse wave generation time difference detected by the pulse wave sensor. There is known a method of obtaining a propagation velocity by using the above method. This is the pulse wave velocity measuring device described in Japanese Patent Application Laid-Open No. 60-220037. In the conventional pulse wave velocity measuring device, the reference point for determining the time difference was often determined based on the rising start point of the pulse wave, but this rising start point has a gentle curve shape. In many cases, it was difficult to accurately detect the rising start point. Therefore, based on the maximum amplitude point of the pulse wave,
For example, the maximum amplitude point of the pulse wave itself is used as a reference point, or 1 of the maximum amplitude of the rising portion of the pulse wave is used.
A method has been proposed in which a point corresponding to / 5 is set as the reference point.

[0003]

By the way, a pulse wave propagating in an artery is formed by combining a traveling wave and a reflected wave generated when the traveling wave is rebounded by a blood vessel wall such as a blood vessel bifurcation. However, as shown in FIG. 5, since the influence of the reflected wave on the pulse wave is generally small, the maximum amplitude point of the pulse wave may be estimated as the maximum amplitude point of the traveling wave.
However, as the arteriosclerosis progresses, the influence of the reflected wave in the pulse wave gradually increases as shown in FIG. 11, and the maximum amplitude point of the pulse wave is determined based on the maximum amplitude point of the reflected wave. If the reference point is determined based on the maximum amplitude point of the pulse wave, the maximum amplitude point of the reflected wave greatly changes depending on the degree of arterial stiffness, or the shape of the artery at the site where the pulse wave is detected. It was inevitable that there would be variations in the set locations.

The present invention has been made in view of the above circumstances, and an object thereof is to obtain a pulse wave which maintains a high measurement accuracy regardless of the degree of hardening of the artery of the subject. It is to provide a propagation velocity measuring device.

[0005]

A first means for solving the problems is to propagate in an artery of a living body based on a difference in generation time of a pair of heartbeat synchronizing waves detected by a pair of heartbeat synchronizing wave sensors mounted on a part of the living body. In a pulse wave velocity measuring device for measuring a pulse wave velocity, (a) maximum slope line determining means for determining a maximum slope line passing through the maximum slope point of the heartbeat synchronizing wave and having a slope of the maximum slope point. And (b) baseline determining means for determining a baseline connecting the minimum point on the rising side and the minimum point on the falling side of the heartbeat synchronizing wave, and (c) the maximum slope line determined by the maximum slope line determining means. And a reference point determining means for determining an intersection with the baseline determined by the baseline determining means as a reference point for determining the time difference.

[0006]

According to the first aspect of the present invention, the maximum slope line which passes through the maximum slope point of the heartbeat synchronous wave and has the slope of the maximum slope point is determined by the maximum slope line determining means, and the heart rate is determined by the baseline determination means. A baseline connecting the minimum point on the rising side and the minimum point on the falling side of the synchronous wave is determined, and the intersection of the maximum slope line and the baseline is determined as a reference point for determining the time difference by the reference point determining means. You. Therefore, since the reference point that is not affected by the reflected wave in the pulse wave is determined, even in the subject whose arteriosclerosis has progressed, there is no variation in the setting point of the reference point, and it propagates in the artery of the living body. The measurement accuracy of the pulse wave propagation velocity is improved as much as possible.

[0007]

[Second Means for Solving the Problem] Propagation in an artery of a living body based on a difference in generation time of a pair of heartbeat synchronizing waves detected by a pair of heartbeat synchronizing wave sensors mounted on a part of the living body. In a pulse wave velocity measuring device for measuring a pulse wave velocity, (d) maximum slope line determining means for determining a maximum slope line passing through the maximum slope point of the heartbeat synchronizing wave and having the slope of the maximum slope point. And (e) determining a maximum amplitude line that passes through the maximum amplitude point of the heartbeat synchronizing wave and that has a slope parallel to a base line that connects the minimum point on the rising side and the minimum point on the falling side of the heartbeat synchronizing wave. The maximum amplitude line determining means, and (f) the intersection point of the maximum slope line determined by the maximum slope line determining means and the maximum amplitude line determined by the maximum amplitude line determining means, with respect to the maximum amplitude line. A vertical line that is hung vertically Based on the intersection of the beat synchronization wave and a reference point determining means for determining a reference point for determining the time difference is to include.

[0008]

In this way, the maximum gradient line determining means determines the maximum gradient line that passes through the maximum gradient point of the heartbeat synchronous wave and has the gradient of the maximum gradient point, and determines the maximum amplitude line. When the maximum amplitude line passing through the maximum amplitude point of the heartbeat synchronization wave and having a slope parallel to the base line connecting the minimum point on the rising side and the minimum point on the falling side of the heartbeat synchronization wave is determined by the reference, By a point determining means, a reference point for determining the time difference is determined based on an intersection of a perpendicular heartbeat synchronous wave dropped perpendicularly to the maximum amplitude line from an intersection of the maximum slope line and the maximum amplitude line. Is done. Therefore, since the reference point that is not affected by the reflected wave in the pulse wave is determined, even in the subject whose arteriosclerosis has progressed, there is no variation in the setting point of the reference point, and it propagates in the artery of the living body. The measurement accuracy of the pulse wave propagation velocity is improved as much as possible.

[0009]

[Third Means for Solving the Problem] Propagation in an artery of a living body based on a difference in generation time of a pair of heartbeat synchronizing waves respectively detected by a pair of heartbeat synchronizing wave sensors mounted on a part of the living body. The pulse wave propagation velocity measuring device for measuring the propagation velocity of a pulse wave includes a reference point determining means for determining a maximum slope point of the heartbeat synchronizing wave as a reference point for determining the time difference.

[0010]

[Effects of the third invention] By doing so, since the reference point that is not affected by the reflected wave in the pulse wave is determined, even in the subject whose arteriosclerosis has progressed, the setting point of the reference point varies. Therefore, the measurement accuracy of the propagation velocity of the pulse wave propagating in the artery of the living body can be improved as much as possible.

[0011]

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a perspective view showing an automatic blood pressure measuring device 8 with a pulse wave velocity measuring function.

In FIG. 1, a box 10 is provided with a through hole 14 into which a right arm 12 of a subject is inserted. In the through hole 14, a bag-shaped flexible cloth and a rubber bag are provided. A belt 16 which is provided with a cuff 15 formed on the inner peripheral surface thereof and held in a cylindrical shape is provided. Further, a first armrest 17 for supporting the right arm 12 of the subject protruding from the through-hole 14 is provided at the rear side of the through-hole 14 so as to be inclined upward, and a tip of the first armrest 17 is provided. In order to detect an electrocardiographic waveform generated with the action potential of the myocardium of the subject, the electrode 18 is disposed so as to be in good contact with the wrist of the right arm 12 of the subject. . The first armrest 17 keeps the muscles from the elbow to the wrist of the right arm 12 of the subject constantly relaxed so that an accurate ECG waveform can always be detected from the wrist of the subject. It has an optimal support surface shape that supports the entire area from the elbow to the wrist so that it can be leaned. On the left side of the box 10, a second armrest 19 for supporting the left arm 13 of the subject is provided horizontally. In order to detect the electric induction waveform, the electrode 18 is disposed so as to make good contact with the wrist of the left arm 13 of the subject. The second armrest 19 is also similar to the first armrest 17 so that the muscles from the elbow to the wrist of the left arm 13 of the subject are continuously relaxed from the elbow to the wrist. It has an optimal support surface shape to support it. An operation switch 20, a stop switch 24, a printer 26, a card insertion slot 28, and the like are provided on an operation panel 20 of the box 10, and a systolic blood pressure indicator 32, a diastolic blood pressure indicator 34, a pulse A number display 36 and a time display 38 are provided, respectively.

FIG. 2 is a block diagram for explaining a circuit configuration of the automatic blood pressure measuring device 8. In FIG. 2, the cuff 15 is connected to a pressure sensor 40, a switching valve 42, and an air pump 44 via a pipe 46. The switching valve 42 is configured to supply a pressure into the cuff 15 to allow a pressure to be supplied. It is configured to be able to switch between three states: a state, a slow discharge state in which the cuff 15 is gradually discharged, and a rapid discharge state in which the cuff 15 is rapidly discharged. Further, the belt 1 is provided with the cuff 15 on the inner peripheral surface and is wound in a cylindrical shape.
One end of 6 is fixed, and the other end is configured to be tightened by a drum 50 driven by a DC motor 48 with a speed reducer. The pressure sensor 40 detects the pressure in the cuff 15 and supplies a pressure signal SP representing the pressure to the static pressure discrimination circuit 52 and the pulse wave discrimination circuit 54, respectively.

The static pressure discriminating circuit 52 includes a low-pass filter, discriminates a cuff pressure signal SK representing a steady pressure included in the pressure signal SP, ie, a cuff pressure, and converts the cuff pressure signal SK into an A / D converter 56. To the electronic control unit 58 via The pulse wave discrimination circuit 54 includes a band-pass filter, and a pulse wave signal S which is a vibration component of the pressure signal SP.
The pulse wave signal SM ₁ to discriminate the M ₁ in frequency A / D
The electric power is supplied to the electronic control device 58 via the converter 60. The cuff pulse wave represented by the pulse wave signal SM ₁ is a pressure vibration wave generated from a brachial artery (not shown) and transmitted to the cuff 15 in synchronization with the heartbeat of the subject. In the present embodiment, the cuff 15
The pressure sensor 40 and the pulse wave discrimination circuit 54 function as a heartbeat synchronous wave sensor, and the cuff pulse wave corresponds to the heartbeat synchronous wave.

The electronic control unit 58 includes a CPU 62, R
The CPU 62 is configured by a so-called microcomputer including an OM 64, a RAM 66, and an I / O port (not shown). The CPU 62 processes an input signal according to a procedure stored in the ROM 64 in advance while using the temporary storage function of the RAM 66. To output drive signals and display signals. That is, when measuring the blood pressure, the CPU 62 drives the DC motor 48 with a speed reducer in accordance with a predetermined procedure to wind the cuff 15 around the upper arm of the living body, and drives the air pump 44 to cause the cuff 15 to move the upper arm. Portion, and then the switching valve 42 is driven to gradually reduce the compression pressure of the cuff 15. Based on the pulse wave signal SM ₁ and the cuff pressure signal SK obtained in the slow down process, the blood pressure is oscillometrically determined. The value is determined, and the blood pressure value is displayed on the systolic blood pressure display 32 and the diastolic blood pressure display 34, and at the same time, sequentially stored in the blood pressure value storage area 69 of the storage device 68. The storage device 68 is a magnetic disk,
It is constituted by a well-known storage device such as a magnetic tape, a volatile semiconductor memory, or a nonvolatile semiconductor memory.

The electrocardiographic induction device 70 includes the right arm 12 of the subject.
Pair of electrodes 1 brought into contact with the wrist of the left arm 13 and the wrist of the left arm 13
Through 8, an electrocardiographic waveform indicating the action potential of the myocardium, that is, a so-called electrocardiogram is continuously detected, and a signal indicating the electrocardiographic waveform is supplied to the electronic control device 58. In the present embodiment, the electrocardiographic lead device 70 and the electrode 1
Reference numeral 8 functions as a heartbeat synchronous wave sensor, and the electrocardiographic lead waveform corresponds to the heartbeat synchronous wave.

FIG. 3 is a functional block diagram for explaining a main part of a control function corresponding to the first invention of the electronic control unit 58 in the automatic blood pressure measuring device 8. As shown in FIG. In FIG. 3, the pressure increasing control means 78 first switches the switching valve 42 to the pressure supply state and drives the air pump 44 to reduce the compression pressure of the cuff 15 to a predetermined target cuff pressure value P ₁ (for example, about 180 mmHg). The pressure value of the cuff 15 is gradually reduced by gradually switching the switching valve 42 to the slow exhaust pressure state. After the blood pressure measurement is completed, the switching valve 42 is switched to the rapid exhaust pressure state. By switching, the compression pressure of the cuff 15 is rapidly discharged. The blood pressure measuring means 80 is well known based on the change in the amplitude of the cuff pulse wave collected by the pulse wave discriminating circuit 54 via the pressure sensor 40 in the slow pressure lowering process of gradually lowering the compression pressure of the cuff 15. The systolic blood pressure SBP and the diastolic blood pressure DBP of the subject are determined by the oscillometric method, and the pulse rate HR is calculated based on the cuff pulse wave generation interval.

The time difference calculating means 82 detects the cuff pulse sequentially detected by the pressure sensor 40 from the R wave of the electrocardiographic lead waveform sequentially detected by the electrocardiographic lead device 70 as shown in FIG. sequentially calculates the time difference TD _RP to a predetermined reference point T _S to be described later generated in every period of the wave. Then, the propagation velocity calculating means 84 calculates the propagation velocity V _M1 (m / sec) of the cuff pulse wave based on the time difference TD _RP actually calculated from the preset mathematical formula 1. In Equation 1, L is the distance (m) from the left ventricle to the pressed portion of the pressure sensor 40 via the aorta, and T _PEP is the precursory emission from the R wave of the electrocardiographically induced waveform to the reference point T _S of the aortic wave. It is a period (sec). For the distance L and the pre- _ejection period T _PEP , values experimentally obtained in advance are used.

[0019]

## EQU1 ## _VM1 = L / ( _TDRP - _TPEP )

The maximum slope determining means 86 is shown in FIG.
The maximum slope point K of the cuff pulse wave_maxThat is,
The point where the differential waveform of the cuff pulse wave shows the maximum value is
Determined from the peak point, the maximum slope point K_maxTo
It passes and its maximum slope K _maxMaximum inclination with inclination of
Oblique line L_Kmax(Corresponding to the broken line in the figure) is determined. Baseline decision maker
Step 88 is a minimum point on the rising side of the cuff pulse wave.
A baseline BL (see FIG. 1) connecting the
(Corresponding to the dotted line). The reference point determining means 90
The maximum inclination line L determined by the large inclination line determination means 86
_KmaxAnd the baseline BL determined by the baseline determining means 88
The time difference TD from the intersection of_RPReference point T for finding_S
To determine.

The change value determination section 92, adjacent one another change value of the propagation velocity V _M1 of the cuff pulse wave which is sequentially calculated by the propagation velocity calculating means 84, i.e., the amount of change or rate of change is less than a predetermined value, for example, It is determined whether it has become 0.1 (m / sec) or less or 3% or less. The propagation speed determining unit 94 determines, for example, the propagation speed calculating unit 84 from within the area where the change value judging unit 92 determines that the adjacent mutual change value of the cuff pulse wave propagation speed _VM1 has become equal to or less than a predetermined value.
From the beginning of the propagation speed V _M1 of the cuff pulse wave calculated by
The average value of the beat is determined as the propagation speed V _M2 of the pulse wave propagating in the artery of the living body.

Further, the corrected propagation speed calculating means 97
From pre-stored equation 2, the blood pressure based on the diastolic blood pressure DBP and pulse rate HR measured by the measuring means 80, preset constant pressure value BP _t (e.g. 80
mmHg) and corrected to the value at the pulse rate HR _t (e.g. 70 bpm) (normalized) to said cuff pulse wave modification propagation velocity V _M3 (m / sec) is calculated. In Equation 2,
Factor A is intended to be pre-determined based on Equation 3 by the coefficient value determining means 96, in proportion to the propagation velocity V _M2, is a coefficient value that varies in inverse proportion to the diastolic blood pressure DBP. Here, the constants B, C, and D in Expression 3 and the constant E in Expression 2 are obtained experimentally in advance.

[0023]

[Number 2] _{V M3 = V M2 + A (} BP t -DBP) + E (HR t -HR)

[0024]

A = BV _M2 −C (DBP) + D

FIG. 6 is a flow chart for explaining the main control operation of the electronic control unit 58. In step SA1 of FIG. 6 (hereinafter, the steps are omitted), it is determined whether or not the magnetic card 74 has been inserted into the card insertion slot 28 of the card reading device 72. If the determination in step SA1 is denied, the routine ends. If the determination is affirmed, the magnetic card 74 is determined in SA2.
Is read.

In the subsequent SA3, it is determined whether the read ID signal is a signal registered in the storage area of the storage device 68 in advance. If the determination in SA3 is denied, that is, if the ID signal recorded on the magnetic card 74 has not been registered, SA16 described later is executed, and the magnetic card 74 is sent out from the card insertion slot 28. However, when the determination in SA3 is affirmed, that is, when the magnetic card 7
If the ID signal recorded in No. 4 has already been registered,
In A4, it is determined whether the activation switch 22 for measuring blood pressure has been operated.

If the determination at SA4 is denied, the process waits until the determination is affirmed. However, if the determination in SA4 is affirmative, SA5 and SA6 corresponding to the boost control means 78 are executed. First, at SA5, the switching valve 42 is switched to the pressure supply state and the air pump 4
4 is driven and the cuff pressure P is set to a preset target cuff pressure P.
_After the pressure is increased to ₁ (for example, a pressure of about 180 mmHg), the air pump 44 is stopped. Next, SA6
, The switching valve 42 is switched to the slow exhaust pressure state to start slow pressure reduction in the cuff 15.

Subsequently, in SA7, the pulse wave signal SM
₁ is read, and it is determined whether or not one pulse wave is detected. If this determination is denied, SA7 is repeatedly executed.
Is executed, the blood pressure value determination routine of SA8 corresponding to is executed.
In this blood pressure value determination routine, based on the change in the amplitude of the pulse wave sequentially detected during the slow down process of the cuff pressure P,
The systolic blood pressure value SBP ₁ and the diastolic blood pressure value DBP according to a well-known oscillometric blood pressure value determining algorithm.
₁ and the average blood pressure value MBP ₁ are determined, and the pulse rate HR ₁ is determined based on the pulse wave generation interval.

Next, in SA9, the systolic blood pressure value SBP
_It is determined whether ₁ and the diastolic blood pressure value DBP ₁ have been determined. If this judgment is denied, SA7 to SA7
9 is repeatedly executed. However, if this determination is affirmed, in subsequent SA10, the measured systolic blood pressure value SBP ₁ , diastolic blood pressure value DBP ₁ , and average blood pressure value M
BP ₁ , pulse rate HR ₁ and measurement date and time are stored in the storage device 6
8 is stored for each subject in the blood pressure value storage area 69 and displayed on the systolic blood pressure display 32, the diastolic blood pressure display 34, and the pulse rate display 36, respectively.

[0030] Subsequently, in SA11 corresponding to the propagation velocity determining means 94, the average of the second of the propagation velocity V _M1 of the storage area are stored, the first three beats propagation velocity V _M1 described later RAM66 By calculating the value, the propagation speed V _M2 of the cuff pulse wave is determined. Then, in SA12 corresponding to the subsequent coefficient value determining means 96, the coefficient A in the previously stored equation 2 is replaced by the previously stored equation 3
From the propagation velocity V _M2 and SA determined in SA11
It is determined based on the minimum blood pressure value DBP determined in 8.

Subsequently, at SA13 corresponding to the corrected propagation velocity calculating means 97, S
Minimum blood pressure DBP and pulse rate HR measured in A8
Based on the above, the cuff pulse wave is corrected to a value at a preset constant blood pressure value BP _t and pulse rate HR _t , that is, a normalized corrected propagation velocity V _M3 is calculated.

Subsequently, the SA corresponding to the boost control means 78
At 14, the switching valve 42 is switched to the rapid exhaust pressure state, whereby the rapid exhaust pressure in the cuff 15 is started.
Then, in the subsequent SA15, as shown in FIG. 8, the systolic blood pressure SBP ₁ and the like are displayed and output on the recording paper 100 by the printer 26. That is, recording paper 1
At the upper left position on 00, the subject's name 102 is displayed, and below it, the artery determined according to FIG. 9 from the measurement date and time, blood pressure value, pulse rate, and the corrected propagation velocity _VM3 . List of degree of cure 104, trend graph 10
6 are sequentially displayed. As a method of determining the degree of arteriosclerosis, for example, it is determined by selecting a predetermined value of the degree of arteriosclerosis according to the calculated value of the corrected propagation velocity _VM3 based on a table as shown in FIG. This table is experimentally determined in advance, and the artery of the subject loses its flexibility as the value of the arteriosclerosis degree increases. In the trend graph 106, a bar line indicating the systolic blood pressure value and the diastolic blood pressure value at an upper end and a lower end respectively, a mark indicating a pulse rate, and a mark indicating a degree of arteriosclerosis correspond to the blood pressure measurement time on the horizontal axis, ie, time. Displayed along axis 108.
Then, when the subsequent SA16 is executed, the magnetic card 74 is sent out from the card insertion slot 28.

FIG. 7 differs from the main routine of FIG.
Interval to be executed when R wave of electrocardiographically induced waveform is detected
It is a flow chart which shows an inclusion routine. Figure 7 Smell
Then, in SB1, an R wave of an electrocardiographically induced waveform was generated.
The time is read. Next, at SB2, the pulse wave signal
SM₁Is detected for one beat. This judgment
If is denied, SB2 is repeated.
However, if this judgment is affirmed, the maximum slope line that follows is determined.
At SB3 corresponding to the means 86, the function shown in FIG.
Maximum pulse point K of pulse wave_maxHowever, for example, the derivative of the cuff pulse wave
The waveform is determined based on the point of maximum and
Maximum slope K of_maxAnd its maximum slope K
_maxSlope line L having a slope of_KmaxIs determined. Next
In SB4 corresponding to the base line determining means 88,
The minimum point on the rising side and the minimum point on the falling side of the wave are connected.
The baseline BL is determined. Then, the reference point determining means 90
Corresponding to SB5, determined in SB3
Maximum slope L_KmaxAnd the baseline B determined in SB4
The intersection with L is the time difference TD_RPReference point T for finding
_SIs determined as

In the following SB6, the reference point T of the cuff pulse wave
_The time when _S occurred is read. Next, in SB7 corresponding to the time difference calculating means 82, as shown in FIG. 4, the reference point from the R-wave of the cuff pulse wave of the ECG waveform T _S
TD _RP is calculated. Subsequently, in SB8 corresponding to the propagation velocity calculating means 84, the propagation velocity V _M1 of the cuff pulse wave is calculated based on the time difference TD _RP actually obtained in SB7 from Equation 1 stored in advance, and , Are temporarily stored in the first storage area of the RAM 66.

Next, SB9 corresponding to the change value judging means 92
, The propagation speeds V _M1 and R calculated in SB8
Mutual change value of the propagation velocity V _M1 calculated in the previous cycle stored in the first storage area of the AM66, i.e. the variation or the rate of change is less than a predetermined value, for example, 0.1 (m /
sec) or less, or 3% or less. If this determination is denied, this routine is ended. If this determination is affirmed, the process proceeds to SB1.
At 0, the propagation speed V _M1 calculated at SB8 is temporarily stored in the second storage area of the RAM 66.

[0036] As described above, according to this embodiment, in SB3 corresponding to the maximum slope line determination unit 86, passes through the maximum inclination point K _max of the cuff pulse wave, and its maximum slope point K
A maximum slope line L _Kmax having a slope of _max is determined, and a base line BL connecting the minimum point on the rising side and the minimum point on the falling side of the cuff pulse wave is determined in SB4 corresponding to the base line determining means 88. Then, at SB5 corresponding to the reference point determining means 90, the maximum slope line L _Kmax and the base line BL
Reference point T to the intersection with calculates the time difference TD _RP
Determined as _S. Therefore, since the reference point T _{S which} is not affected by the reflected wave in the pulse wave is determined, even in the subject who has advanced arteriosclerosis, the set point of the reference point T _S does not vary, and the inside of the artery of the living body is not affected. Measurement accuracy of the propagation speed of the propagating pulse wave is improved as much as possible.

According to the present embodiment, the propagation speed V
_If the change value of _M1 is equal to or smaller than the predetermined value, the average value of three beats of the propagation speed V _M1 of the cuff pulse wave determined in SB9 corresponding to the change value determination means 92 is equal to SA11 corresponding to the propagation speed determination means 94. _Is determined as the propagation velocity V _M2 of the pulse wave propagating in the artery of the living body. Accordingly, regardless of the change in the compression pressure of the cuff 15, the propagation speed V _M1 calculated sequentially is calculated.
Since There always propagation velocity V _M1 of time as shown a substantially constant value is determined as the final propagation speed V _M2, the measurement accuracy of the pulse wave velocity is improved.

Further, in the present embodiment, the SA 13 corresponding to the corrected propagation velocity calculating means 97 is obtained from the previously stored equation 2 by the SA 13 corresponding to the blood pressure measuring means 80.
Based on the minimum blood pressure value DBP and the pulse rate HR measured by 8, the corrected propagation velocity V _M3 corrected (normalized) to the values at the preset constant blood pressure value BP _t and pulse rate HR _t is calculated. . Therefore, even if the blood pressure value and the pulse rate of the living body are slightly different each time it is measured, the pulse wave propagation velocity calculated by the present apparatus is equal to the corrected propagation velocity V _M3 at the constant blood pressure value and the pulse rate. Since the normalized pulse wave velocity is normalized, it is possible to directly use the measured pulse wave velocity as an index indicating a change over time in the arterial stiffness of the subject.

The corrected propagation speed V _M3 measured by this device is calculated by the SA 12 corresponding to the coefficient value determining means 96.
In the above, the coefficient A determined from the propagation velocity V _M1 calculated in SB8 and the diastolic blood pressure value DBP measured in SA8, that is, the influence of the individual difference in the arteriosclerosis degree is calculated based on Equation 3 stored in advance. Since it is calculated using a coefficient that also takes into consideration, it is possible to use the measured pulse wave velocity as an index representing individual differences in arteriosclerosis degree.

Further, according to the automatic blood pressure measuring device 8 of the present embodiment, the pulse wave velocity is measured at the same time as the blood pressure measurement, and the pulse wave velocity is directly used as an index showing the change with time of the arteriosclerosis. Since it is converted into usable information, more biometric information is provided to the subject, and it becomes possible to judge the health condition from various angles. Further, the degree of arterial stiffness corresponding to the calculated pulse wave velocity is displayed as a trend graph, so that a temporal change can be more easily and accurately grasped.

Next, the essential part of the control function of the electronic control unit 58 in the automatic blood pressure measuring device 8 corresponding to the second aspect of the invention will be explained based on the functional block diagram of FIG. Note that portions having the same configuration as those of the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted.

In FIG. 10, the maximum amplitude line determining means 98
As shown in FIG. 11, the slope passing through the maximum amplitude point M _max of the cuff pulse wave and parallel to the base line connecting the minimum point on the rising side and the minimum point on the falling side of the cuff pulse wave is The maximum amplitude line L _Mmax (corresponding to the two-dot chain line in the figure) is determined. The reference point determining means 99 is provided with the maximum inclination line determining means 8.
6 maximum inclination line L _Kmax determined by (corresponding to dashed line in the figure), from the intersection point X ₁ between the maximum amplitude line L _Mmax which is determined by the largest amplitude line determination unit 98, with respect to the maximum amplitude line L _{Mm ax} the point corresponding to 1/5 of the amplitude values of the intersection point X ₂ of the cuff pulse wave of a perpendicular line which is lowered vertically is determined as the reference point T _S.

Next, the main part of the control operation of the electronic control unit 58 corresponding to the functional block diagram of FIG. 10 will be described. Since the main routine in this control operation is the same as that shown in FIG. 6, the description is omitted, and an interrupt executed when an R wave of an electrocardiographic lead waveform is detected with respect to the main routine in FIG. Only the routine will be described with reference to FIG. In FIG. 12, SC1 and SC2 are SB
1 to SB2.

Next, in SC3 corresponding to the maximum inclination line determining means 86, the maximum inclination point K _max of the cuff pulse wave shown in FIG. 11 is determined based on, for example, the point at which the differential waveform of the cuff pulse wave shows the maximum value. Is determined and its maximum slope point K
_The maximum slope line L _Kmax that passes through _max and has the slope of its maximum slope point K _max is determined. Next, in SC4 corresponding to the maximum amplitude line determining means 98, a slope that passes through the maximum amplitude point M _max of the cuff pulse wave and is parallel to the base line connecting the minimum point on the rising side and the minimum point on the falling side of the cuff pulse wave. The maximum amplitude line L _{Mmax with} is determined. At SC5 corresponding to the reference point determining unit 99, a maximum slope line L _Kmax determined in SC3, from the intersection X ₁ maximum amplitude line L _Mmax determined in SC4, the maximum amplitude line L
_The point corresponding to, for example, ⅕ of the amplitude value of the intersection point X ₂ with the perpendicular cuff pulse wave that is lowered perpendicular to _Mmax is the reference point T.
Determined as _S. Then, the following SC6 to SC10
Are executed in the same manner as in SB6 to SB10 described above.

The largest as described above, according to this embodiment, which passes through the maximum inclination point K _max of the cuff pulse wave in SC3 corresponding to the maximum slope line determining means 86, having a slope of the maximum slope point K _max When the slope line L _Kmax is determined and the maximum amplitude line L _{Mmax that} is in contact with the maximum amplitude point M _max of the cuff pulse wave is determined in SC4 corresponding to the maximum amplitude line determination means 98, it corresponds to the reference point determination means 99. In SC5,
Intersection X ₁ between the maximum slope line L _Kmax and the maximum amplitude line L _Mmax
From the amplitude value of the intersection point X ₂ of the cuff pulse wave of a perpendicular line which is lowered vertically with respect to the maximum amplitude line L _Mmax, the point corresponding to, for example, 1/5 is determined as a reference point T _S. In this way, the reference point T _{S which is} not affected by the reflected wave in the pulse wave
Therefore, even in the subject whose arteriosclerosis has progressed, the setting point of the reference point P _S does not vary, and the measurement accuracy of the propagation velocity of the pulse wave propagating in the artery of the living body is improved as much as possible. To be made.

Next, the main part of the control function corresponding to the third invention of the electronic control unit 58 in the automatic blood pressure measuring device 8 will be described with reference to the functional block diagram of FIG. Note that portions having the same configuration as those of the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted. In FIG. 13, the reference point determination means 76 determines the maximum slope point K _max of the heartbeat synchronization wave based on, for example, a point at which the differential waveform of the heartbeat synchronization wave shows the maximum value, and determines the maximum slope point _Kmax as the reference. Point T
Determined as _S.

Next, the main part of the control operation of the electronic control unit 58 corresponding to the functional block diagram of FIG. 13 will be described. Since the main routine in this control operation is the same as that shown in FIG. 6, the description is omitted, and an interrupt executed when an R wave of an electrocardiographic lead waveform is detected with respect to the main routine in FIG. Only the routine will be described with reference to FIG. In FIG. 14, SD1 and SD2 are SB
1 to SB2. Next, in SD3 corresponding to the reference point determining means 76, the maximum slope point K _max of the cuff pulse wave shown in FIG. 11 is determined based on, for example, the point at which the differential waveform of the cuff pulse wave shows the maximum value. , The maximum slope point K _max is determined as the reference point T _S. Then, the subsequent SD4 to SD8 are executed in the same manner as SB6 to SB10 described above.

[0048] As described above, according to this embodiment, in SD3 corresponding to the reference point determining unit 76, the maximum inclination point K _max of the cuff pulse wave is determined as a reference point T _S. Therefore, the reference point T _{S which is} not affected by the reflected wave in the pulse wave
Therefore, even in the subject whose arteriosclerosis has progressed, there is no variation in the setting point of the reference point P _S , and the measurement accuracy of the propagation velocity of the pulse wave propagating in the artery of the living body is improved as much as possible. To be made.

Although various embodiments of the present invention have been described in detail with reference to the drawings, the present invention can be applied to other embodiments.

For example, in the above-mentioned embodiment, electrocardiographic induction is performed.
Time difference TD from waveguide type and cuff pulse wave _RPIs calculated
By the propagation speed V_M1Was calculated, but
One detected by each pair of pulse wave sensors attached
Time difference TD from paired pulse wave_RPPropagation by calculating
Speed V_M1May be configured to be calculated.
In such a case, the reference for each pulse wave
Point T_SIs required.

Further, in the above-described embodiment, the intersection X of the maximum slope line L _Kmax and the maximum amplitude line L _{Mmax at} SC5.
_The point corresponding to ⅕ of the amplitude value of the intersection point X ₂ with the cuff pulse wave of the perpendicular line drawn vertically from the maximum amplitude line L _Mmax was determined as the reference point T _{S from 1} but, for example, 1 /
Instead of 5, it may be 1/3, 1/10, or the like, and the intersection point corresponding to the leg of the perpendicular may be determined as the reference point T _S.

The present invention can be modified in various other ways without departing from the spirit of the invention.

[Brief description of drawings]

FIG. 1 is a perspective view illustrating a configuration of an automatic blood pressure measurement device 8 with a pulse wave velocity measuring function according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a circuit configuration of the embodiment of FIG. 1;

FIG. 3 is a functional block diagram illustrating a main part of a control function corresponding to the first invention of the electronic control unit 58 of the embodiment of FIG. 1;

FIG. 4 is a time chart for explaining a time difference TD _RP obtained by the control operation of the embodiment of FIG. 1;

FIG. 5 is an enlarged view of a cuff pulse wave for explaining a reference point T _S obtained by a control operation corresponding to the first invention in the embodiment of FIG. 1;

FIG. 6 is a flowchart illustrating a main part of a control operation corresponding to the first invention of the electronic control device 58 of the embodiment of FIG. 1;

7 is a flowchart showing an interrupt routine executed when an R wave of an electrocardiographic lead waveform is detected in the main routine shown in FIG. 6;

8 is a diagram showing an example of a display output by the printer 26 of the embodiment of FIG.

FIG. 9 is a diagram showing an example of a table used when converting the measured corrected propagation velocity _{VM3 back} into a predetermined arteriosclerosis degree.

FIG. 10 shows the second embodiment of the electronic control unit 58 of the embodiment of FIG.
FIG. 3 is a functional block diagram illustrating a main part of a control function according to the present invention.

11 is an enlarged view of a cuff pulse wave for explaining a reference point T _S obtained by a control operation corresponding to the second aspect of the embodiment of FIG. 1;

FIG. 12 shows the second embodiment of the electronic control unit 58 of the embodiment of FIG. 1;
FIG. 7 is a flowchart illustrating a main part of a control operation according to the present invention.
It is a flowchart which shows the interruption routine performed when the R wave of an electrocardiogram lead waveform is detected.

FIG. 13 shows the third embodiment of the electronic control unit 58 of the embodiment of FIG. 1;
FIG. 3 is a functional block diagram illustrating a main part of a control function according to the present invention.

FIG. 14 is a view showing the third example of the electronic control unit 58 of the embodiment of FIG. 1;
FIG. 7 is a flowchart illustrating a main part of a control operation according to the present invention.
It is a flowchart which shows the interruption routine performed when the R wave of an electrocardiogram lead waveform is detected.

[Explanation of symbols]

 8: Automatic blood pressure measuring device with pulse wave velocity measuring function 15: Cuff (heartbeat synchronizing wave sensor) 18: Electrode 70: Electrocardiographic induction device (heartbeat synchronizing wave sensor) 76: Reference point determining means 86: Maximum slope line determining means 88: Base line determining means 90: Reference point determining means 98: Maximum amplitude line determining means 99: Reference point determining means

Claims (3)

[Claims] 1. A propagation speed of a pulse wave propagating in an artery of a living body based on a generation time difference of a pair of heartbeat synchronizing waves detected by a pair of heartbeat synchronizing wave sensors mounted on a part of the living body. In the pulse wave velocity measuring device for measuring, a maximum slope line determining means for determining a maximum slope line passing through the maximum slope point of the heartbeat synchronization wave and having a slope of the maximum slope point, and a rising side of the heartbeat synchronization wave A baseline determining means for determining a baseline connecting the minimum point and the minimum point on the falling side, a maximum slope line determined by the maximum slope line determining means, and an intersection of the baseline determined by the baseline determining means. A reference point determining means for determining the reference point for determining the time difference, and a pulse wave velocity measuring device. 2. A propagation speed of a pulse wave propagating in an artery of the living body based on a difference in generation time of a pair of heartbeat synchronizing waves detected by a pair of heartbeat synchronizing wave sensors mounted on a part of the living body. In a pulse wave velocity measuring device for measuring, a maximum slope line determining means for determining a maximum slope line passing through the maximum slope point of the heartbeat synchronization wave and having a slope of the maximum slope point, and a maximum amplitude of the heartbeat synchronization wave. A maximum amplitude line determining means that determines a maximum amplitude line that passes through a point and has a slope parallel to a base line that connects the minimum point on the rising side and the minimum point on the falling side of the heartbeat synchronization wave; and the maximum slope line. From the intersection of the maximum inclination line determined by the determination means and the maximum amplitude line determined by the maximum amplitude line determination means, to the intersection point with the heartbeat synchronizing wave of the perpendicular line drawn vertically to the maximum amplitude line. Based on the above A reference point determining means for determining a reference point for determining a time difference, and a pulse wave velocity measuring device. 3. A propagation speed of a pulse wave propagating in an artery of the living body based on a difference in generation time of a pair of heartbeat synchronizing waves detected by a pair of heartbeat synchronizing wave sensors mounted on a part of the living body. The pulse wave velocity measuring device for measuring includes a reference point determining means for determining a maximum inclination point of the heartbeat synchronization wave as a reference point for determining the time difference.