JPH09253061A - Oscillometric type automatic sphygmomanometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oscillometric type automatic sphygmomanometer capable of obtaining sufficient blood pressure measurement accuracy even in the case of shortening time required for blood pressure measurement. SOLUTION: By an envelope deciding means 84, the curve of a forth order or more for minimizing the deviation in a direction parallel to a cuff pulse wave amplitude axis from the amplitude values of respective cuff pulse waves of cuff pulse wave strings successively detected in a cuff pressure gradual speed change period in the two-dimensional coordinate of a cuff pressure axis and the cuff pulse wave amplitude axis is decided as the envelope of the cuff pulse wave string. Thus, even when the number of the cuff pulse waves successively detected through a cuff 15 is reduced since the cuff pressure gradual speed change period is shortened for the purpose of reducing the uncomfortable feeling of a person to be measured or the like, the sufficient blood pressure measurement accuracy is obtained since the envelope for most accurately indicating the change of the amplitude value of the cuff pulse wave string is decided.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an oscillometric automatic blood pressure measuring device.

[0002]

2. Description of the Related Art As a device for measuring the blood pressure value of a living body,
For example, during the cuff pressure gradual change period that slowly changes the compression pressure of the cuff wrapped around a part of the living body, the amplitude value of the cuff pulse wave generated in synchronization with the pulse of the living body detected through the cuff A well-known automatic oscillometric blood pressure measuring device is of a type that determines a blood pressure value of a living body based on a change in the shape of an envelope determined from the change. For example, it is an automatic blood pressure measuring device described in Japanese Patent Laid-Open No. 6-292660.

[0003]

By the way, in the above automatic blood pressure measuring apparatus, it has been proposed to shorten the period for slowly changing the cuff pressure for the purpose of reducing discomfort of the person to be measured. However, if the cuff pressure gradual change period is shortened, the number of cuff pulse waves detected through the cuff decreases, so the cuff pressure axis representing the cuff pressure value and the amplitude value of the cuff pulse wave are represented. The envelope of the cuff pulse wave train cannot be accurately determined from the change in the amplitude value of each cuff pulse wave in the cuff pulse wave train aligned in the cuff pressure axis direction in the two-dimensional coordinate with the cuff pulse wave amplitude axis. The measurement accuracy of the blood pressure value, which is determined based on the change in the shape of the line, is reduced.

The present invention has been made in view of the above circumstances, and an object thereof is to obtain an oscillometric formula capable of obtaining sufficient blood pressure measurement accuracy even when the time required for blood pressure measurement is shortened. An object is to provide an automatic blood pressure measurement device.

[0005]

A first aspect of the present invention for achieving the above object is to provide a cuff pressure-reducing means for gently changing the compression pressure of a cuff wound around a part of a living body. Blood pressure that determines the blood pressure value of the living body based on the change in the shape of the envelope determined from the change in the amplitude value of the cuff pulse wave that is sequentially generated in synchronization with the pulse of the living body detected through the cuff during the rapid change period In an oscillometric automatic blood pressure measuring device having a determining means, (a) in a two-dimensional coordinate system of a cuff pressure axis representing the pressure value of the cuff and a cuff pulse wave amplitude axis representing the amplitude value of the cuff pulse wave, Envelope determining means for determining a curve of a fourth order or more that minimizes the deviation from the amplitude value of each cuff pulse wave of the cuff pulse wave train arranged in the cuff pressure axis direction and determining this curve as the envelope curve is included. Especially.

[0006]

According to the first aspect of the present invention, for example, the cuff pulse wave from the amplitude value of each cuff pulse wave sequentially detected through the cuff by the envelope determining means during the cuff pressure gradual change period. The fourth or higher-order curve obtained so that the shift in the direction parallel to the amplitude axis is minimized is determined as the envelope curve of the cuff pulse wave train. If it is a fourth-order curve or more, there is a convex curve having a pair of inflection points and an upper peak point located between them, and a pair of inflection points and an upper peak point located between them are present. Since it is common with the envelope curve of the cuff pulse train, the maximum amplitude point of the cuff pulse train, which is the basis for determining the systolic blood pressure value and the diastolic blood pressure value, is relatively accurately determined even from a relatively small number of amplitude values. Is possible.

Therefore, by shortening the cuff pressure gradual change period, even if the number of cuff pulse waves sequentially detected through the cuff decreases, the change in the amplitude value of the cuff pulse wave train can be represented most accurately. Since the envelope curve is determined, sufficient blood pressure measurement accuracy can be obtained.

More preferably, (b) the cuff pulse wave abnormal value judging means for judging whether each of the cuff pulse waves is an abnormal value or not, and (c) the envelope determining means has the fourth or higher order. Prior to obtaining the curve, the position of the fourth or higher-order curve is corrected by multiplying the deviation of the cuff pulse wave determined to be an abnormal value by the cuff pulse wave abnormal value determination means by a predetermined abnormal value correction coefficient. Curve position correcting means for

In this way, the abnormal cuff pulse wave caused by the body movement or arrhythmia of the person to be measured is judged to be an abnormal value by the cuff pulse wave abnormal value judging means, and the cuff pressure is judged. The deviation from the amplitude value of each cuff pulse wave of the cuff pulse wave train arranged in the axial direction in the direction parallel to the cuff pulse wave amplitude axis is multiplied by a predetermined abnormal value correction coefficient to obtain a curve of the fourth or higher order. Since the position is suitably corrected, the accuracy of determining the envelope is improved, and the accuracy of measuring the blood pressure value is further improved.

[0010]

[Second Means for Solving the Problem] Similarly, the gist of the second invention for achieving the above object is to provide a cuff for gently changing the compression pressure of the cuff wound around a part of the living body. Determine the blood pressure value of the living body based on the change in the shape of the envelope determined from the change in the amplitude value of the cuff pulse wave that is sequentially generated in synchronism with the pulse of the living body detected via the cuff during the pressure gradual change period In an oscillometric automatic blood pressure measuring device having blood pressure determining means, (a) in a two-dimensional coordinate system of a cuff pressure axis representing the pressure value of the cuff and a cuff pulse wave amplitude axis representing the amplitude value of the cuff pulse wave. , A curve between the upper peak point and the lower peak point of the pair of cubic curves so that the deviation from the amplitude value of each cuff pulse wave of the cuff pulse wave train arranged in the cuff pressure axis direction is minimized. And find the connecting curve connecting the upper peak points, The coupling curve is to include an envelope determination means for determining as said envelope.

[0011]

According to the second aspect of the present invention, for example, the cuff pulse wave from the amplitude value of each cuff pulse wave sequentially detected through the cuff by the envelope determining means in the cuff pressure gradual change period. The connection curve obtained so that the deviation in the direction parallel to the amplitude axis is minimized is determined as the envelope of the cuff pulse wave train. Such a curve has a convex curve having a pair of inflection points and an upper peak point located between them.
Since it is common with the envelope curve of the cuff pulse wave train having a pair of inflection points and the upper peak point located between them, it is the basis for determining the systolic and diastolic blood pressure values even from a relatively small number of amplitude values. It becomes possible to relatively accurately determine the maximum amplitude point of the cuff pulse wave train.

Therefore, by shortening the cuff pressure gradual change period, even if the number of cuff pulse waves sequentially detected through the cuff decreases, the change in the amplitude value of the cuff pulse wave train can be represented most accurately. Since the envelope curve is determined, sufficient blood pressure measurement accuracy can be obtained.

Further, preferably, (b) the cuff pulse wave abnormal value judging means for judging whether the cuff pulse wave is an abnormal value or not, and (c) the envelope curve determining means determines the connecting curve. Prior to obtaining, the curve position correction means for correcting the position of the connecting curve by multiplying the deviation of the cuff pulse wave determined to be an abnormal value by the cuff pulse wave abnormal value determination means by a predetermined abnormal value correction coefficient. And are included.

In this way, the abnormal cuff pulse wave caused by the body movement or arrhythmia of the person to be measured is judged to be an abnormal value by the cuff pulse wave abnormal value judging means, so that the cuff pressure is determined. The position of the connecting curve is preferable by multiplying the deviation from the amplitude value of each cuff pulse wave in the axial cuff pulse wave train in the direction parallel to the cuff pulse wave amplitude axis by a predetermined abnormal value correction coefficient. Therefore, the accuracy of determining the envelope is improved, and the accuracy of measuring the blood pressure value is further improved.

[0015]

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 oscillometric automatic blood pressure measuring device 8 according to an embodiment of the present invention.

In FIG. 1, a box body 10 is provided with a through hole 14 for inserting the right arm 12 of a person to be measured. Inside the through hole 14, a bag-shaped flexible cloth and a rubber bag are provided. A belt 16 is provided, which is provided with a cuff 15 composed of the above on the inner peripheral surface thereof and is held in a cylindrical shape. An operation switch 20, a stop switch 24, a printer 26, a card slot 28, and the like are provided on an operation panel 20 of the box 10, and a systolic blood pressure indicator 32 and a diastolic blood pressure indicator 3 are provided on a display panel 30.
4. A pulse rate display 36 and a time display 38 are provided.

FIG. 2 is a block diagram illustrating the circuit configuration of the oscillometric automatic blood pressure measuring device 8.
In FIG. 2, the cuff 15 includes a pressure sensor 40 and a switching valve 4.
2 and the air pump 44 are connected to each other via a pipe 46. The switching valve 42 has a pressure supply state that allows the supply of pressure into the cuff 15, and a rapid exhaust pressure that rapidly exhausts the inside of the cuff 15. It is configured to be able to switch between two states. Further, one end of the belt 16 having the cuff 15 on the inner peripheral surface and wound in a cylindrical shape is fixed, and the other end is tightened by a drum 50 driven by a DC motor 48 with a speed reducer. ing.
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 the cuff pressure signal SK representing the steady pressure included in the pressure signal SP, that is, the cuff pressure and discriminates the cuff pressure signal SK from the A / D converter 56. To the electronic control unit 58. 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 the brachial artery (not shown) and transmitted to the cuff 15 in synchronization with the heartbeat of the measurement subject.

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 winds the cuff 15 around the upper arm of the living body by driving the DC motor 48 with a speed reducer according to a predetermined procedure, then switches the switching valve 42 to the pressure supply state, and By driving the pump 44, the compression pressure of the cuff 15 is gradually increased, and the pulse wave signal SM ₁ obtained in the gradual increase process
And the blood pressure value is determined by the oscillometric method based on the cuff pressure signal SK, and the blood pressure value is displayed as the systolic blood pressure indicator 3
2 and the lowest blood pressure indicator 34, and at the same time, sequentially store them in the blood pressure value storage area 69 of the storage device 68. The storage device 68 is a magnetic disk, a magnetic tape,
It is configured by a well-known storage device such as a volatile semiconductor memory or a non-volatile semiconductor memory.

FIG. 3 is a functional block diagram for explaining a main part of the control function of the electronic control unit 58 in the oscillometric automatic blood pressure measuring device 8. In FIG. 3, the pressure increase control means 80 first switches the switching valve 42 to the pressure supply state and drives the air pump 44 to set the compression pressure of the cuff 15 to the target cuff pressure value P ₁ (for example, 180 m).
The pressure is gradually increased to a pressure value of about mHg), and after the blood pressure measurement is completed, the switching valve 42 is switched to the rapid exhaust pressure state to rapidly exhaust the compression pressure of the cuff 15.

The blood pressure determining means 82 includes an envelope determining means 84, a cuff pulse wave abnormal value determining means 86, and a curve position correcting means 88, which will be described later, and the cuff pulse wave abnormal value determining means 86 and the curve position correcting means. Based on the deviation described later, which is preferably corrected by the means 88, from the change in the shape of the envelope determined by the envelope determining means 84, the systolic blood pressure value SBP and the minimum blood pressure value of the measurement subject are measured by the well-known oscillometric method. Determine the blood pressure value DBP and the like. For example, in the two-dimensional coordinates of the cuff pressure axis and the cuff pulse wave amplitude axis as shown in FIG. 4, the amplitude value of the envelope determined based on the amplitude value of each cuff pulse wave is the maximum value of the envelope. The cuff pressure value at the point of 1/3 of the amplitude value is calculated as the systolic blood pressure value SBP and the diastolic blood pressure value DBP, respectively, and the cuff pressure value at the maximum amplitude point of the envelope and the cuff pulse wave having the maximum amplitude value are calculated. The average value with the cuff pressure value at the time of occurrence is calculated as the average blood pressure value MBP.

The envelope determining means 84 is configured to gradually increase the compression pressure of the cuff 15 during the cuff pressure gradually increasing period,
Through the pressure sensor 40, the static pressure discriminating circuit 52 sequentially detects the cuff pressure value represented by the cuff pressure signal SK, and the pulse wave discriminating circuit 54 sequentially detects the cuff pulse wave represented by the pulse wave signal SM ₁ . Measure the cuff pressure value when the amplitude value and each cuff pulse wave are generated, and measure the cuff pressure at the two-dimensional coordinates of the cuff pressure axis that represents the cuff pressure value and the cuff pulse wave amplitude axis that represents the cuff pulse wave amplitude value. The upper peak point of a curve of 4th order or more that minimizes the deviation from the amplitude value of each cuff pulse wave in the cuff pulse wave train aligned in the axial direction, for example, in the direction parallel to the cuff pulse wave amplitude axis, The curve between the pair of lower peak points sandwiched therebetween is determined as the envelope.

Here, the curve of the fourth or higher order is a convex curve having a pair of inflection points and an upper peak point located between them if it is the fourth or higher order curve, and it is Since it is common with the envelope curve of a cuff pulse wave train having a pair of inflection points and an upper peak point located between them, comparison is made even from a relatively small number of amplitude values by approximating with a curve of 4th order or more. This is because the maximum amplitude point of the envelope can be determined accurately. The maximum amplitude point of the envelope of the cuff pulse wave train is an important point that is the basis for determining the systolic blood pressure value SBP and the diastolic blood pressure value DBP, and can be obtained with sufficient accuracy by the conventional interpolation method or approximation method. It wasn't.

Specifically, in the envelope determining means 84, for example, as shown in FIG. 4, when the cuff pulse wave amplitude axis is the y axis and the cuff pressure axis is the x axis, a quartic curve y is obtained. = A
Deviation of each coefficient in x ⁴ + bx ³ + cx ² + dx + e from the amplitude value (y _M1 , y _M2 , ... y _Mn ) of each cuff pulse wave in the direction parallel to the y-axis from the quartic curve to Z _n ( = Y
(X _n) -y _Mn, except determining the envelope by determined as the total sum is minimized despite multiplied by outliers correction coefficient K _n to be described later n = 1,2,3 ···) To do. The deviation represents the distance between the envelope and the amplitude value of the cuff pulse wave in the direction parallel to the cuff pulse wave amplitude axis.

The cuff pulse wave abnormal value judging means 86 judges whether or not each cuff pulse wave is an abnormal value. For example, by determining whether or not the amplitude value of the cuff pulse wave exceeds the predetermined amplitude value α, the amplitude value of the cuff pulse wave is determined by the predetermined amplitude value α.
If it exceeds, the cuff pulse wave is determined to be an abnormal value. The predetermined value α is experimentally set in advance in order to determine an abnormal value due to motion artifacts, and is an amplitude value at which the cuff pulse wave is almost impossible under normal conditions.

The curve position correcting means 88 determines the quadratic curve by the envelope determining means 84 when the cuff pulse wave abnormal value determining means 86 determines that the cuff pulse wave is an abnormal value. Prior to the abnormal value determination time (n = m), the deviation from the amplitude value of the cuff pulse wave to the envelope in the direction parallel to the cuff pulse wave amplitude axis Z _m (= y (x _m ) −y
Are those by multiplying a preset outlier correction coefficient K _m in _mm) for correcting the position of the fourth order curve, for example, Z _n deviation to determine an envelope in the envelope determination unit 84 With respect to the abnormal value correction coefficient K _n that has been multiplied in advance with respect to the cuff pulse wave that is determined to be an abnormal value, the abnormal value correction coefficient K _m is set to 1/2, and the cuff that is determined not to be an abnormal value is set. For the pulse wave, the abnormal value correction coefficient K _n is set to 1.

FIG. 5 is a flow chart for explaining the main control operation of the electronic control unit 58 of the oscillometric automatic blood pressure measuring device 8. In step SA1 (hereinafter, steps are omitted), it is determined whether or not the magnetic card 72 is inserted into the card insertion slot 28 of the card reading device 70. If the determination of SA1 is negative, this routine is ended, but if the determination is affirmative, the ID signal recorded in the magnetic card 72 in SA2 is read.

At subsequent SA3, it is judged whether or not the read ID signal is previously registered in the storage area of the storage device 68. If the determination in SA3 is negative, that is, if the ID signal recorded in the magnetic card 72 is unregistered, SA10 described below is executed and the magnetic card 72 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 2 is already registered, the subsequent S
In A4, it is determined whether the activation switch 22 for measuring blood pressure has been operated.

If the determination at SA4 is negative, the process waits until the determination becomes affirmative. However, if the determination in SA4 is affirmative, in SA5 corresponding to the pressure increase control means 80, the switching valve 42 is switched to the pressure supply state and the air pump 44 is driven to set the cuff pressure P to the preset target. A gradual pressure increase process is started in which the pressure is gradually increased to the cuff pressure P ₁ (for example, a pressure of about 180 mmHg).

Next, SA6 corresponding to the blood pressure determining means 82
In, the blood pressure determination routine shown in SB1 to SB7 of FIG. 6 described later is executed. Subsequently, at SA7, the systolic blood pressure value SBP, the diastolic blood pressure value DBP, the average blood pressure value MBP, the pulse rate HR, and the measurement date and time are stored in the blood pressure value storage area 69 of the storage device 68 for each subject. It is displayed on the systolic blood pressure display 32, the diastolic blood pressure display 34, and the pulse rate display 36, respectively.

Then, the SA corresponding to the boost control means 80
At 8, the switching valve 42 is switched to the rapid exhaust pressure state, so that the rapid exhaust pressure in the cuff 15 is started. Then, in the subsequent SA9, the systolic blood pressure value SBP and the like are displayed and output on the recording paper by the printer 26. Then, by executing the subsequent SA10, the magnetic card 72 is sent out from the card insertion slot 28.

FIG. 6 shows a blood pressure determination routine executed at SA6 in the main routine shown in FIG. At SB1, it is determined whether one pulse of the cuff pulse wave is detected. If this judgment is denied, SB1
Is repeatedly executed, and when this determination is affirmative, SB2 corresponding to the subsequent cuff pulse wave abnormal value determination means 86
When the amplitude value of the cuff pulse wave exceeds the predetermined amplitude value α by determining whether the amplitude value of the cuff pulse wave exceeds the predetermined amplitude value α, the cuff pulse wave is abnormal. It is determined to be a value.

SB corresponding to the curve position correcting means 88
In 3, the SB2 is determined to be an abnormal value.
For the pulse wave, the above-mentioned abnormal value correction coefficient K_mParable
For example, 1/2 is given. Then in SB4, the cuff vein
Wave amplitude value (y_M1, Y_M2・ ・ ・ Y_Mn) And cuff pulse wave
Cuff pressure value (x₁, X_Two, ... x_n) Is each
Cuff pulse that is determined to be an abnormal value while being stored
Wave outlier correction coefficient K _m1/2 is not an outlier
Cuff pulse wave outlier correction coefficient K_nAs one
Is stored.

Next, at SB5, the pressure value of the cuff 15 is a preset target pressure value P _t (for example, 180 mm).
It is determined whether or not the pressure value reaches about Hg). If this determination is negative, SB1 to SB5 are repeatedly executed, but if this determination is positive, at SB6 corresponding to the envelope determining means 84, the cuff pulse wave amplitude axis is the y-axis, When the cuff pressure axis is the x axis, each coefficient in the quartic curve y = ax ⁴ + bx ³ + cx ² + dx + e is a pair of lower peaks that sandwich the upper peak point of the quartic curve from the amplitude value of each cuff pulse wave. Deviation in the direction parallel to the y-axis to the curve between the points Z _n [= y (x _n ) −y _Mn , where n = 1, 2
..] is multiplied by the correction coefficient K _n , and the sum is calculated to be the minimum,
The envelope consisting of this quartic curve is determined.

That is, in the above SB6, the coefficients a, b, and quadratic coefficients a, b,
c, d, and e are calculated respectively.

[0036]

[Formula 1] Z ₁ = K ₁ [(ax ₁ ⁴ + bx ₁ ³ + cx ₁ ² + dx ₁ + e) -y _{M 1} ] Z ₂ = K ₂ [(ax ₂ ⁴ + bx ₂ ³ + cx ₂ ² + dx ₂ + e) -y _M2] · · · Z _n = K _{n ^{[(ax n 4 + bx n 3}} + cx n 2 + dx n + e n) -y Mn ]

Next, at SB7, the systolic blood pressure value SBP and the diastolic blood pressure value DBP of the subject are determined from the change in the shape of the envelope by a well-known oscillometric method, and the cuff pulse wave is generated. The pulse rate of the subject is calculated from the interval. For example, in the two-dimensional coordinates of the cuff pressure axis and the cuff pulse wave amplitude axis as shown in FIG. 4, the cuff pressure value at the point where the amplitude value of the envelope becomes ⅓ of the maximum amplitude value of the envelope curve, respectively. The average blood pressure value is calculated as the maximum blood pressure value SBP and the minimum blood pressure value DBP, and the average value of the cuff pressure value at the maximum amplitude point of the envelope and the point at which the amplitude value of the cuff pulse wave has the maximum value is the average blood pressure value. MBP
Is calculated as

As described above, according to this embodiment, the envelope determining means 84 causes
A curve of the fourth or higher order that minimizes the total deviation from the amplitude value of each cuff pulse wave that is sequentially detected via the cuff 15 in the direction parallel to the cuff pulse wave amplitude axis is the cuff pulse wave train. Determined as the envelope. If it is a fourth-order curve or more, there is a convex curve having a pair of inflection points and an upper peak point located between them, and a pair of inflection points and an upper peak point located between them are present. Since it has a common cuff pulse wave train envelope curve, the maximum amplitude point of the cuff pulse wave train, which is an important point that is the basis for the determination of the systolic blood pressure value SBP and the diastolic blood pressure value DBP, is obtained even from a relatively small number of amplitude values. It is possible to make a relatively accurate determination. Therefore, by shortening the cuff pressure gradual change period, even if the number of cuff pulse waves sequentially detected via the cuff 15 decreases, the envelope that most accurately represents the change in the amplitude value of the cuff pulse wave train. Since the line is determined, sufficient blood pressure measurement accuracy can be obtained.

Further, since the pressing time by the cuff 15 is shortened, the discomfort of the person to be measured is suitably reduced.
Furthermore, since a doctor or a nurse can know the blood pressure value of the patient in a shorter time than before, it is possible to perform a quick treatment in an emergency. In addition, since the blood pressure value can be determined from a small number of cuff pulse waves, it is possible to measure the blood pressure value with relatively high accuracy even in a situation where noise is likely to occur.

Further, according to this embodiment, since the blood pressure value of the living body is determined based on the change in the amplitude of the cuff pulse wave which is sequentially detected in the cuff pressure gradually increasing period, the cuff pressure gradually decreasing period. In comparison with the case where the blood pressure value of the living body is determined based on the change in the amplitude of the cuff pulse wave that is sequentially detected in step 1, the blood pressure is measured for the time period in which the pressure value of the cuff 15 is preliminarily increased to the predetermined target pressure value P _t. The time required can be shortened, and the discomfort of the person to be measured can be reduced more preferably. Further, it is possible to perform more prompt treatment in an emergency.

Next, another embodiment of the present invention will be described in detail with reference to the drawings. 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. FIG. 7 is a functional block diagram illustrating a main part of a control function of the electronic control device 58 in the oscillometric automatic blood pressure measurement device 8.

In FIG. 7, the envelope determining means 90 is operated by the static pressure discrimination circuit 5 via the pressure sensor 40 during the cuff pressure gradually increasing period during which the compression pressure of the cuff 15 is gradually increased.
2, the cuff pressure value represented by the cuff pressure signal SK and the cuff pulse wave represented by the pulse wave signal SM ₁ are sequentially detected by the pulse wave discrimination circuit 54, and the amplitude value of each cuff pulse wave and each cuff pulse wave The cuff pressure value is measured, and the cuff pressure axis representing the cuff pressure value and the cuff pulse wave amplitude axis representing the cuff pulse wave amplitude value are 2
In dimensional coordinates, a pair of symmetrical 3 pairs that minimizes the deviation from the amplitude value of each cuff pulse wave of the cuff pulse wave train arranged in the cuff pressure axis direction, for example, in the direction parallel to the cuff pulse wave amplitude axis.
A connecting curve between the upper peak point and the lower peak point of the following curves and connecting the upper peak points is determined as the envelope.

Here, the envelope is determined from the above-mentioned connecting curve because, in such a curve, there is a convex curve having a pair of inflection points and an upper peak point located between them. However, since it is common with the envelope of a cuff pulse wave train having a pair of inflection points and an upper peak point located between them, a relatively small amplitude value can be obtained by approximating with such a curve. This is because the maximum amplitude point of the envelope can be determined relatively accurately even from. The maximum amplitude point of the envelope of the cuff pulse wave train is the maximum blood pressure value SBP and the minimum blood pressure value DB.
This is an important point that serves as a basis for determining P, and cannot be obtained with sufficient accuracy by the conventional interpolation method or approximation method.

Specifically, in the envelope determining means 90, for example, as shown in FIG. 4, when the cuff pulse wave amplitude axis is the y axis and the cuff pressure axis is the x axis, a pair of symmetrical shapes is obtained. Three
The upper peak points of the pair of cubic curves coincide with the coefficients of the cubic curve y = ax ³ + bx ² + cx + d, and
3 from the amplitude value (y _M1 , y _M2 , ... y _Mn ) of each cuff pulse wave
Deviation to the next curve in the direction parallel to the y-axis Z _n (= y (x
_n ) -y _Mn , where n = 1, 2, 3 ...) is multiplied by the above-mentioned abnormal value correction coefficient K _n to obtain the minimum sum so that the envelope is determined.
The deviation Z _n represents the distance between the envelope and the amplitude value of the cuff pulse wave in the direction parallel to the cuff pulse wave amplitude axis.

In this embodiment, the control operation of the electronic control unit 58 of the oscillometric automatic blood pressure measuring device 8 is executed in the same manner as the flow chart shown in FIG.

FIG. 8 shows a blood pressure determination routine executed at SA6 in the main routine shown in FIG. 5 in this embodiment. SC1 to SC5 are SB
It is executed in the same manner as 1 to SB5.

Next, the SC corresponding to the envelope determining means 90
6, when the cuff pulse wave amplitude axis is the y axis and the cuff pressure axis is the x axis, a pair of symmetrical cubic curves y = ax ³ + bx ²
The upper peak points of the pair of cubic curves coincide with each other in the coefficient at + cx + d, and the amplitude value (y _M1 ,
y _M2 , ... Y _Mn ) to cubic curve in the direction parallel to the y-axis Z _n (= y (x _n ) −y _Mn , where n = 1,
, 3, 3) are multiplied by the correction coefficient K _n so that the sum of them is calculated to be the minimum, so that the envelope curve formed of the cubic curve is determined.

That is, in SC6, the coefficients a, b, and
c and d are respectively calculated.

[0049]

[Formula 2] Z ₁ = K ₁ [(ax ₁ ³ + bx ₁ ² + cx ₁ + d) -y _{M 1} ] Z ₂ = K ₂ [(ax ₂ ³ + bx ₂ ² + cx ₂ + d) -y _{M 2} ] ・ ・ Z _n = K _{n ^{[(ax n 3 + bx n 2}} + cx n + d n) -y Mn ]

The subsequent SC7 is executed in the same manner as step SB7 described above.

As described above, according to the present embodiment, the envelope determining means 90 allows the cuff pressure to be gradually increased during the above period.
The connecting curve that minimizes the total deviation from the amplitude value of each cuff pulse wave detected through the cuff 15 in the direction parallel to the cuff pulse wave amplitude axis is the envelope curve of the cuff pulse wave train. It is determined. With such a curve, there is a convex curve having a pair of inflection points and an upper peak point located between them, and having a pair of inflection points and an upper peak point located between them. The maximum amplitude point of the cuff pulse wave train, which is the basis of the determination of the systolic blood pressure value SBP and the diastolic blood pressure value DBP, is relatively accurately determined even from a relatively small number of amplitude values because it is common with the envelope curve of the cuff pulse wave train. It becomes possible. Therefore, by shortening the cuff pressure gradual change period, even if the number of cuff pulse waves sequentially detected via the cuff 15 decreases, the envelope that most accurately represents the change in the amplitude value of the cuff pulse wave train. Since the line is determined, sufficient blood pressure measurement accuracy can be obtained.

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

For example, in the above-mentioned embodiment, the blood pressure value of the living body is determined based on the change in the amplitude of the cuff pulse wave which is sequentially detected during the cuff pressure gradually increasing period.
Of course, the blood pressure value of the living body may be determined based on the change in the amplitude of the cuff pulse wave that is sequentially detected during the cuff pressure gradual pressure reduction period.

Further, in the above-mentioned embodiment, the cuff pulse wave abnormal value judging means 86 determines the amplitude value of the cuff pulse wave by a predetermined amplitude value α, which is experimentally obtained in advance and in which almost no cuff pulse wave can be taken.
By exceeding the above, it was configured to determine that the cuff pulse wave is an abnormal value, for example, when the generation interval of the cuff pulse wave changes more than a predetermined value with respect to the moving average value, It may be configured to determine that the cuff pulse wave is an abnormal value. In such a case, the moving average value ΔT _AVE [= (T
_{i + 1} −T _i ) + (T _{i + 2} −T _{i + 1} ) + ... + (T _{i + n}
-T _{i + n-1} ) / n] for this cuff pulse wave generation interval Δ
Change amount of T [= (P _{i + n + 1} −P _{i + n} )] (= | ΔT−Δ
T _AVE |) is calculated, and the cuff pulse wave is determined to be an abnormal value when the amount of change exceeds a predetermined value β.
The predetermined value β is a change amount sufficient to determine that the cuff pulse wave is an abnormal value, and is experimentally obtained in advance. The abnormal value of the cuff pulse wave can be determined by various other methods.

Further, in the above-mentioned embodiment, the deviation correction
The means 88 corrects the deviation by the correction coefficient K. _nMultiply by
It was configured to correct the gap by
Correction coefficient K_nOf course, it is not limited to 1/2, but 1/3
Alternatively, it can take various numerical values such as 1/5, and
The optimum value is selected according to the fixed situation.

Further, in the above-mentioned embodiment, the cubic curve or the quartic curve is used as the envelope, but the curve may be a quartic curve or higher. When a fourth-order or higher-order curve is used, a curve portion having a pair of inflection points and an upper peak point between them is used as the envelope of the pulse wave train.

When a curve of fourth order or higher is used as the envelope, the curve itself may be used as the envelope, or a pair of four curves may be used as in the case of the cubic curve described above.
A curve connecting the upper peak points of the following curves or more may be used as the envelope.

In the above-described embodiment, the deviation between the amplitude value of each cuff pulse wave and the envelope is the distance from the amplitude value of each cuff pulse wave to the envelope in the direction parallel to the cuff pulse wave amplitude axis. However, for example, the difference between the amplitude value of each cuff pulse wave and the envelope is calculated as the distance from the amplitude value of each cuff pulse wave to the envelope in the direction parallel to the cuff pressure axis. It can be obtained in various other modes.

The present invention can take various other modes without departing from the spirit of the present invention.

[Brief description of drawings]

FIG. 1 is a perspective view illustrating a configuration of an oscillometric automatic blood pressure measurement device 8 that is an embodiment of the present invention.

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

3 is a functional block diagram illustrating a main part of a control function of an electronic control unit 58 in the embodiment of FIG.

FIG. 4 is a diagram illustrating a cuff pulse wave train in two-dimensional coordinates of a cuff pressure axis and a cuff pulse wave amplitude axis, showing an envelope of the cuff pulse wave train.

5 is a flowchart illustrating a main part of control operation of an electronic control unit 58 in the embodiment of FIG.

FIG. 6 is a flowchart showing a blood pressure determination routine in a control operation of the electronic control unit 58 in the embodiment of FIG.

FIG. 7 is an electronic control unit 58 according to another embodiment of the present invention.
FIG. 3 is a functional block diagram illustrating a main part of the control function of FIG.

8 is a flowchart showing a blood pressure determination routine in a control operation of the electronic control device 58 in the embodiment of FIG.

[Explanation of symbols]

 8: Oscillometric automatic blood pressure measuring device 15: Cuff 82: Blood pressure determining means 84: Envelope determining means 86: Cuff pulse wave abnormal value determining means 88: Curve position correcting means 90: Envelope determining means

Claims (4)

[Claims] 1. In a cuff pressure gradual change period in which the compression pressure of a cuff wound around a part of a living body is gently changed, the cuff pressure is sequentially generated in synchronization with the pulse of the living body detected through the cuff. In an oscillometric automatic blood pressure measuring device having a blood pressure determining means for determining the blood pressure value of the living body based on the change in the shape of the envelope determined from the change in the amplitude value of the cuff pulse wave, the pressure value of the cuff is In the two-dimensional coordinates of the cuff pressure axis shown and the cuff pulse wave amplitude axis showing the amplitude value of the cuff pulse wave, the deviation from the amplitude value of each cuff pulse wave of the cuff pulse wave line arrayed in the cuff pressure axis direction is minimum. An oscillometric automatic blood pressure measuring device, characterized in that it includes an envelope determining means for determining a curve of a quartic or higher order such that the curve becomes the envelope. 2. A cuff pulse wave abnormal value determining means for determining whether or not each of the cuff pulse waves is an abnormal value, and the cuff pulse wave prior to the envelope determining means determining the fourth or higher order curve. Curve position correcting means for correcting the position of the fourth or higher-order curve by multiplying the deviation of the cuff pulse wave determined to be an abnormal value by the pulse wave abnormal value determining means by a predetermined abnormal value correction coefficient; The oscillometric automatic blood pressure measurement device according to claim 1, wherein the oscillometric automatic blood pressure measurement device is included. 3. A cuff pressure gradual change period in which the compression pressure of a cuff wound around a part of a living body is gradually changed, and the cuff pressure is sequentially generated in synchronization with the pulse of the living body detected through the cuff. In an oscillometric automatic blood pressure measuring device having a blood pressure determining means for determining the blood pressure value of the living body based on the change in the shape of the envelope determined from the change in the amplitude value of the cuff pulse wave, the pressure value of the cuff is In the two-dimensional coordinates of the cuff pressure axis shown and the cuff pulse wave amplitude axis showing the amplitude value of the cuff pulse wave, the deviation from the amplitude value of each cuff pulse wave of the cuff pulse wave line arrayed in the cuff pressure axis direction is minimum. Which is a curve between an upper peak point and a lower peak point of a pair of cubic curves such that the connecting curve connecting the upper peak points is determined, and the connecting curve is determined as the envelope. Oscillomet, characterized by including line determining means Click-type automatic blood pressure measurement device. 4. A cuff pulse wave abnormal value determining means for determining whether or not each of the cuff pulse waves is an abnormal value, and the cuff pulse wave abnormality before the envelope determining means obtains the connecting curve. Curve position correcting means for correcting the position of the connecting curve by multiplying the deviation of the cuff pulse wave determined to be an abnormal value by the value determining means by a predetermined abnormal value correction coefficient. The oscillometric automatic blood pressure measurement device according to claim 3.