JP3953073B2 - Oscillometric automatic blood pressure measuring device - Google Patents

Description

  The present invention relates to an oscillometric automatic blood pressure measurement device.

As an apparatus for measuring the blood pressure value of a living body, for example, in the cuff pressure slow change period in which the pressure of the cuff wound around a part of the living body is gradually changed, the apparatus is synchronized with the pulse of the living body detected through the cuff. An oscillometric automatic blood pressure measurement device 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 a change in amplitude value of a cuff pulse wave generated in this manner is well known. For example, the automatic blood pressure measuring device described in Patent Document 1 is that.
JP-A-6-292660

  By the way, in the automatic blood pressure measurement device, it has been proposed to shorten the cuff pressure gradual change period for the purpose of reducing the discomfort of the measurement subject. However, if the cuff pressure gradual change period is shortened, the number of cuff pulse waves detected via the cuff is reduced, 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 arranged in the cuff pressure axis direction in two-dimensional coordinates with the cuff pulse wave amplitude axis. The measurement accuracy of the blood pressure value determined based on the change in the shape of the line is reduced.

  The present invention has been made in the background as described above, and the object of the present invention is to provide an oscillometric automatic blood pressure measurement that can provide sufficient blood pressure measurement accuracy even when the time required for blood pressure measurement is shortened. To provide an apparatus.

  In order to achieve the above object, the gist of the present invention is that the living body detected through the cuff during the cuff pressure gradual change period in which the compression pressure of the cuff wound around a part of the living body is gradually changed. In an oscillometric automatic blood pressure measuring device provided with a blood pressure determining means for determining a blood pressure value of a living body based on a change in the shape of an envelope determined from a change in amplitude value of a cuff pulse wave that is sequentially generated in synchronization with a pulse (A) In the two-dimensional coordinates of the cuff pressure axis representing the cuff pressure value and the cuff pulse wave amplitude axis representing the amplitude value of the cuff pulse wave, each cuff of the cuff pulse wave train arranged in the cuff pressure axis direction is shown. A curve between the upper peak point and the lower peak point of the pair of cubic curves that minimizes the deviation from the amplitude value of the pulse wave is obtained, and a connecting curve connecting the upper peak points is obtained. Envelope determination to determine a connecting curve as the envelope Lies in that it includes means.

  In this way, in the cuff pressure gradual change period by the envelope determination means, the amplitude value of each cuff pulse wave sequentially detected via the cuff, for example, in a direction parallel to the cuff pulse wave amplitude axis. The connection curve obtained so as to minimize the deviation 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, and a cuff having a pair of inflection points and an upper peak point located between them. Since it is the same as the envelope of the pulse wave train, it is possible to determine the maximum amplitude point of the cuff pulse train, which is the basis for determining the systolic blood pressure value and the minimum blood pressure value, even from a relatively small number of amplitude values. It becomes.

  Therefore, by shortening the cuff pressure gradual change period, even if the number of cuff pulse waves sequentially detected via the cuff decreases, the envelope that most accurately represents the change in the amplitude value of the cuff pulse wave train Therefore, sufficient blood pressure measurement accuracy can be obtained.

  Preferably, (b) cuff pulse wave abnormal value determining means for determining whether or not each of the cuff pulse waves is an abnormal value, and (c) the envelope determining means prior to obtaining the connection 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 cuff pulse wave abnormal value determining means by a predetermined abnormal value correction coefficient, There is to include.

  In this way, the abnormal cuff pulse wave caused by the body movement or arrhythmia of the measurement subject is determined to be an abnormal value by the cuff pulse wave abnormal value determination means, so that the cuff pressure axis direction is increased. The position of the connecting curve is suitably corrected by multiplying the deviation in the direction parallel to the cuff pulse wave amplitude axis from the amplitude value of each cuff pulse wave of the arranged cuff pulse wave train by a predetermined abnormal value correction coefficient. Therefore, the accuracy of determining the envelope is improved, and the measurement accuracy of the blood pressure value is further improved.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view showing an oscillometric automatic blood pressure measuring apparatus 8 according to an embodiment of the present invention.

  In FIG. 1, the box 10 is provided with a through hole 14 for inserting the right arm 12 of the person to be measured, and a cuff made of a bag-like flexible cloth and a rubber bag is provided in the through hole 14. A belt 16 having a cylindrical shape with 15 provided on the inner peripheral surface is disposed. The operation panel 20 of the box 10 is provided with a start switch 22, a stop switch 24, a printer 26, a card insertion slot 28, and the like, and a display panel 30 has 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.

  FIG. 2 is a block diagram illustrating the circuit configuration of the oscillometric automatic blood pressure measurement device 8. In FIG. 2, the cuff 15 is connected to the pressure sensor 40, the switching valve 42, and the air pump 44 through a pipe 46, and the switching valve 42 is a pressure supply that allows the supply of pressure into the cuff 15. It is configured to be switched between two states: a state and a rapid exhaust pressure state in which the inside of the cuff 15 is rapidly exhausted. Further, one end of a belt 16 having a cuff 15 provided 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 a cuff pressure signal SK representing a steady pressure, that is, a cuff pressure included in the pressure signal SP, and electronically transmits the cuff pressure signal SK via an A / D converter 56. This is supplied to the control device 58. The pulse wave discriminating circuit 54 includes a band-pass filter. The pulse wave signal SM ₁ that is a vibration component of the pressure signal SP is discriminated in frequency, and the pulse wave signal SM ₁ is passed through the A / D converter 60. This is supplied to the electronic control unit 58. Cuff pulse wave which the pulse wave signal SM ₁ represents is a pressure oscillation wave that is transmitted to the cuff 15 is generated from the brachial artery (not shown) in synchronism with heartbeat of the subject.

The electronic control unit 58 includes a CPU 62, a ROM 64, a RAM 66, and a so-called microcomputer having an I / O port (not shown). The CPU 62 stores in the ROM 64 in advance using the temporary storage function of the RAM 66. The input signal is processed according to the procedure, and a drive signal, a display signal, and the like are output. That is, when measuring blood pressure, the CPU 62 drives the DC motor 48 with a speed reducer according to a predetermined procedure to wind the cuff 15 around the upper arm of the living body, and then switches the switching valve 42 to the pressure supply state. gradually boosting the pressing pressure of the cuff 15 by driving the pump 44, to determine the blood pressure value by oscillometric method, based on the pulse wave signal SM ₁ and the cuff pressure signal SK obtained at the slow speed boost process, the The blood pressure value is displayed on the systolic blood pressure display 32 and the diastolic blood pressure display 34 and simultaneously stored in the blood pressure value storage area 69 of the storage device 68. The storage device 68 is a well-known storage device such as a magnetic disk, a magnetic tape, a volatile semiconductor memory, or a nonvolatile semiconductor memory.

FIG. 3 is a functional block diagram illustrating a main part of the control function of the electronic control device 58 in the oscillometric automatic blood pressure measurement 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 change the compression pressure of the cuff 15 to the target cuff pressure value P ₁ (for example, a pressure of about 180 mmHg). After the blood pressure measurement is completed, the switching valve 42 is switched to the rapid exhaust pressure state, whereby the compression pressure of the cuff 15 is rapidly exhausted.

  The blood pressure determining unit 82 includes an envelope determining unit 84, a cuff pulse wave abnormal value determining unit 86, and a curve position correcting unit 88, which will be described later. By the cuff pulse wave abnormal value determining unit 86 and the curve position correcting unit 88, From the change in the shape of the envelope determined by the envelope determination means 84 based on the deviation corrected later, the systolic blood pressure value SBP and the minimum blood pressure value DBP of the subject are measured by a well-known oscillometric method. Etc. 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 of the envelope. The cuff pressure value at a point that is 1/3 of the amplitude value is calculated as the maximum blood pressure value SBP and the minimum 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. An average value with the occurrence cuff pressure value is calculated as an average blood pressure value MBP.

The envelope determining means 84 converts the cuff pressure value represented by the cuff pressure signal SK by the static pressure discriminating circuit 52 via the pressure sensor 40 during the cuff pressure gradual pressure increase period in which the compression pressure of the cuff 15 is gradually increased. together sequentially detects a cuff pulse wave represented by the pulse-wave signal SM ₁ by discrimination circuit 54 measures the amplitude value and the cuff pressure value at the time of the cuff pulse wave generated in the cuff pulse wave, respectively, cuff represents the pressure value of the cuff In the two-dimensional coordinates of the pressure axis and the cuff pulse wave amplitude axis representing the amplitude value of the cuff pulse wave, for example, the cuff pulse wave amplitude axis from the amplitude value of each cuff pulse wave of the cuff pulse wave array aligned in the cuff pressure axis direction A curve between a pair of lower peak points sandwiching the upper peak point among the quaternary or higher order curves that minimizes the shift in the direction parallel to is determined as the envelope.

  Here, the curve of the fourth or higher order is a curve of the fourth or higher order, and there is a convex curve having a pair of inflection points and an upper peak point located between them. Since it is common to the envelope of the cuff pulse wave train having the inflection points and the upper peak point located between them, it is relatively accurate even from a relatively small number of amplitude values by approximating with a fourth-order or higher curve. This is because the maximum amplitude point of the envelope can be determined. 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 and approximation method. There was no.

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 = ax ⁴ Each coefficient at + bx ³ + cx ² + dx + e is expressed as a deviation Z _n (= y) in the direction parallel to the y-axis from the amplitude value (y _M1 , y _M2 ,..., Y _Mn ) of each cuff pulse wave to the quartic curve. _(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. This 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 determining means 86 determines 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 a predetermined amplitude value α, if the amplitude value of the cuff pulse wave exceeds the predetermined amplitude value α, the cuff pulse wave is expressed as an abnormal value. Judge that there is. Note that this predetermined value α is experimentally set in advance to determine an abnormal value caused by motion artifact or the like, and is, for example, an amplitude value at which the cuff pulse wave can hardly be taken under normal conditions.

When the cuff pulse wave abnormal value determining means 86 determines that the cuff pulse wave is an abnormal value, the curve position correcting means 88 is arranged before the envelope determining means 84 determines the quartic curve. The deviation Z _m (= y (x _m ) −y _Mm ) in the direction parallel to the cuff pulse wave amplitude axis from the amplitude value of the cuff pulse wave at the abnormal value determination time (n = m) to the envelope is previously determined. is intended to correct the position of the fourth-order curve by multiplying the set outlier correction coefficient K _m, for example, pre-multiplied is displaced in Z _n in order to determine an envelope in the envelope determination unit 84 respect outlier correction coefficient K _n are, for cuff pulse wave is determined to be abnormal value sets the 1/2 abnormal value correction coefficient K _m, with respect to the determined cuff pulse wave is not the outliers 1 outlier correction coefficient _{K n} Set to.

  FIG. 5 is a flowchart for explaining a main part of the control operation of the electronic control device 58 of the oscillometric automatic blood pressure measurement device 8. In step SA1 (hereinafter step is omitted), it is determined whether or not the magnetic card 72 has been inserted into the card insertion slot 28 of the card reading device 70. If the determination of SA1 is negative, this routine is terminated. If the determination is positive, the ID signal recorded on the magnetic card 72 is read in SA2.

  In the subsequent SA3, it is determined whether or not the read ID signal is registered in advance in the storage area of the storage device 68. If the determination of SA3 is negative, that is, if the ID signal recorded on the magnetic card 72 is not registered, SA10 described later is executed and the magnetic card 72 is sent out from the card insertion slot 28. However, if the determination of SA3 is affirmative, that is, if the ID signal recorded on the magnetic card 72 has already been registered, it is determined whether or not the activation switch 22 for blood pressure measurement has been operated in subsequent SA4. .

If the determination of SA4 is denied, the process waits until it is affirmed. However, if the determination at SA4 is affirmative, at 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 in advance. A slow pressure increasing 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, in SA6 corresponding to the blood pressure determination means 82, a blood pressure determination routine indicated by SB1 to SB7 in FIG. 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 for each person to be measured in the blood pressure value storage area 69 of the storage device 68. Displayed on the systolic blood pressure display 32, the diastolic blood pressure display 34, and the pulse rate display 36, respectively.

  Subsequently, in SA8 corresponding to the pressure increase control means 80, the switching valve 42 is switched to the rapid exhaust pressure state, whereby the rapid exhaust pressure in the cuff 15 is started. In SA9, the systolic blood pressure value SBP and the like are displayed and output on the recording paper by the printer 26. When the subsequent SA10 is executed, the magnetic card 72 is sent out from the card insertion slot 28.

  FIG. 6 shows a blood pressure determination routine executed in SA6 in the main routine shown in FIG. In SB1, it is determined whether one cuff pulse wave is detected. If this determination is denied, SB1 is repeatedly executed. If this determination is affirmed, the amplitude value of the cuff pulse wave is predetermined in SB2 corresponding to the subsequent cuff pulse wave abnormal value determination means 86. If the amplitude value of the cuff pulse wave exceeds the predetermined amplitude value α, it is determined that the cuff pulse wave is an abnormal value.

Next, in SB3 corresponding to the curve position correcting means 88, the cuff pulse wave which is determined to be abnormal value by SB2, the outlier correction coefficient K _m above example 1/2 is applied. Subsequently, in SB4, the amplitude value of the cuff pulse wave _{(y M1, y M2, ···} y Mn) and the cuff pressure value at the time of cuff pulse wave generator _{(x 1, x 2, ···} x n) each storage In addition, ½ is stored as the abnormal value correction coefficient K _m for the cuff pulse wave determined to be an abnormal value, and 1 is stored as the abnormal value correction coefficient K _n for the cuff pulse wave determined to be not an abnormal value. Is done.

Next, in SB5, for example, the target pressure value _{P t} pressure value of the cuff 15 is set in advance, whether the host vehicle has reached the pressure value of about 180 mmHg) is determined. If this determination is negative, SB1 to SB5 are repeatedly executed. If this determination is positive, in SB6 corresponding to the envelope determination 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 sandwiching the upper peak point of the quartic curve from the amplitude value of each cuff pulse wave total displacement _{Z n [= y (x n) -y Mn} , where n = 1, 2 · ·] in the direction parallel to the y-axis to the curve between points in, what was multiplied each correction coefficient _{K n} Is calculated so as to minimize the above-described envelope curve, and the envelope curve composed of the quartic curve is determined.

  That is, in SB6, the coefficients a, b, c, d, and e of the quaternary formula are obtained so that the total sum of the right sides of Formula 1 is minimized.

[Equation 1]
Z ₁ = K ₁ [(ax ₁ ⁴ + bx ₁ ³ + cx ₁ ² + dx ₁ + e) −y _M1 ]
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, in SB7, the measured person's systolic blood pressure value SBP, diastolic blood pressure value DBP, etc. are determined by the well-known oscillometric method from the change in the shape of the envelope, and from the cuff pulse wave generation interval. The measurer's pulse rate is calculated. 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 values at points where the amplitude value of the envelope is 1/3 of the maximum amplitude value of the envelope are 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 cuff pressure value at the point where the amplitude value of the cuff pulse wave has the maximum value. Calculated as MBP.

  As described above, according to the present embodiment, the cuff pulse wave amplitude axis from the amplitude value of each cuff pulse wave sequentially detected via the cuff 15 in the cuff pressure gradual pressure increase period by the envelope determination means 84. A curve of the fourth or higher order that minimizes the sum total of the deviations in the direction parallel to is determined as the envelope of the cuff pulse wave train. If the curve is a quartic or higher curve, 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 Since the cuff pulse wave train has the same envelope as the cuff pulse wave train, the maximum amplitude point of the cuff pulse train is an important point that is the basis for determining the systolic blood pressure value SBP and the diastolic blood pressure value DBP even from a relatively small number of amplitude values. It becomes possible to determine relatively accurately. Therefore, by shortening the cuff pressure gradual change period, even if the number of cuff pulse waves sequentially detected via the cuff 15 is reduced, 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.

  Moreover, the measurement subject's discomfort is suitably reduced by shortening the compression time by the cuff 15. Furthermore, since a doctor or nurse can know the blood pressure value of a 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, the blood pressure value can be measured with relatively high accuracy even in a situation where noise is likely to occur.

Further, according to the present embodiment, since 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 during the cuff pressure gradual pressure increase period, it is sequentially detected during the cuff pressure gradual pressure decrease period. than if the blood pressure value of the living body is determined based on the change in the amplitude of the cuff pulse wave that is, the time required for only the blood pressure measurement time period for boosting advance the pressure value of the cuff 15 to a predetermined target pressure value P _t It can be shortened, and the discomfort of the measurement subject is further reduced. In addition, 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. In addition, the same code | symbol is attached | subjected to the part which has the same structure as the above-mentioned Example, and description is abbreviate | omitted. FIG. 7 is a functional block diagram illustrating a main part of the 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 performs the cuff pressure value represented by the cuff pressure signal SK by the static pressure discriminating circuit 52 via the pressure sensor 40 during the cuff pressure gradual pressure increasing period in which the compression pressure of the cuff 15 is gradually increased. and thereby sequentially detecting the cuff pulse wave represented by the pulse-wave signal SM ₁ by the pulse-wave filter circuit 54 measures the amplitude value and the cuff pressure value at the time of the cuff pulse wave generated in the cuff pulse wave, respectively, the pressure of the cuff In the two-dimensional coordinates of the cuff pressure axis representing the value and the cuff pulse wave amplitude axis representing the amplitude value of the cuff pulse wave, for example, the cuff from the amplitude value of each cuff pulse wave of the cuff pulse wave sequence aligned in the cuff pressure axis direction A connection between the upper peak point and the lower peak point of a pair of symmetrical cubic curves that minimizes the deviation in the direction parallel to the pulse wave amplitude axis and connects the upper peak points. A curve is determined as the envelope.

  Here, the envelope curve is determined from the above connecting curve. In such a curve, there is a convex curve having a pair of inflection points and an upper peak point located between them. Is common to the envelope of a cuff pulse train having a pair of inflection points and an upper peak point located between them, so that even a relatively small number of amplitude values can be compared by approximating with such a curve. 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 and approximation method. There was no.

Specifically, in the envelope determination 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 cubic curves For each coefficient in y = ax ³ + bx ² + cx + d, the upper peak points of a pair of cubic curves coincide with each other and the cuff pulse wave amplitude values (y _M1 , y _M2 ,... y _Mn ) are cubic. displacement in the direction parallel to the y-axis to the curve _{Z n (= y (x n} ) -y Mn, where n = 1,2,3 ···) obtained by multiplying the outlier correction coefficient _{K n} as described above in The envelope is determined by obtaining the sum of things to be the minimum. This 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 the present embodiment, the control operation of the electronic control device 58 of the oscillometric automatic blood pressure measurement device 8 is executed in the same manner as the flowchart shown in FIG.

  FIG. 8 shows a blood pressure determination routine executed in SA6 in the main routine shown in FIG. 5 in the present embodiment. SC1 to SC5 are executed in the same manner as SB1 to SB5.

Next, in SC6 corresponding to the envelope determining means 90, each of the pair of symmetrical cubic curves y = ax ³ + bx ² + cx + d when the cuff pulse wave amplitude axis is the y axis and the cuff pressure axis is the x axis. Coefficients corresponding to the upper peak points of a pair of cubic curves and directions parallel to the y-axis from the amplitude values (y _M1 , y _M2 ,... Y _Mn ) of the cuff pulse waves to the cubic curves shift in the _{Z n (= y (x n} ) -y Mn, where n = 1,2,3 ···), a is calculated as the sum is minimized although each correction coefficient _{K n} are multiplied As a result, the envelope composed of this cubic curve is determined.

  That is, in SC6, the coefficients a, b, c, and d of the cubic equation are obtained so that the sum of the right sides of Equation 2 is minimized.

[Equation 2]
Z ₁ = K ₁ [(ax ₁ ³ + bx ₁ ² + cx ₁ + d) −y _M1 ]
Z ₂ = K ₂ [(ax ₂ ³ + bx ₂ ² + cx ₂ + d) −y _M2 ]
・
・
・
Z _n = _{K n ^{[(ax n 3 + bx n 2}} + cx n + d n) -y Mn ]

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

  As described above, according to the present embodiment, the cuff pulse wave amplitude axis from the amplitude value of each cuff pulse wave sequentially detected via the cuff 15 in the cuff pressure gradual pressure increase period by the envelope determination means 90. A connection curve that minimizes the sum total of the deviations in the direction parallel to is determined as the envelope of the cuff pulse wave train. If it is such a curve, there is a convex curve having a pair of inflection points and an upper peak point located between them, and has a pair of inflection points and an upper peak point located between them Since it is common with the envelope of the cuff pulse wave train, the maximum amplitude point of the cuff pulse train that is the basis for determining the systolic blood pressure value SBP and the diastolic blood pressure value DBP is determined relatively accurately even from a relatively small number of amplitude values. It becomes possible. Therefore, even if the number of cuff pulse waves sequentially detected via the cuff 15 is reduced by shortening the cuff pressure gradual change period, 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.

  As mentioned above, although one Example of this invention was described in detail based on drawing, this invention is applied also in another aspect.

  For example, in the above-described embodiment, the blood pressure value of the living body is determined based on the change in the amplitude of the cuff pulse wave sequentially detected in the cuff pressure gradual pressure increase period. Of course, the blood pressure value of the living body may be determined based on the change in the amplitude of the detected cuff pulse wave.

Further, in the above-described embodiment, the cuff pulse wave abnormal value determination means 86 determines that the amplitude value of the cuff pulse wave has exceeded a predetermined amplitude value α that can hardly be obtained in advance by an experimentally obtained cuff pulse wave. The cuff pulse wave is determined to be an abnormal value. For example, when the generation interval of the cuff pulse wave changes by a predetermined value or more with respect to the moving average value, the cuff pulse wave is You may be comprised so that it may determine with it being 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−} ) of the cuff pulse wave generation interval until the previous time. ₁ ) / n] is calculated as a change amount (= | ΔT−ΔT _AVE |) of the current cuff pulse wave generation interval ΔT [= (P _{i + n + 1} −P _{i + n} )] with respect to the predetermined value β. If this happens, the cuff pulse wave is determined as an abnormal value. The predetermined value β is an amount of change sufficient to determine that the cuff pulse wave is an abnormal value, and is obtained experimentally in advance. It can be determined by various other methods that the cuff pulse wave is an abnormal value.

In the illustrated embodiment, the deviation correction means 88 has been configured to modify the deviation by multiplying the correction coefficient K _n to the deviation, the correction coefficient K _n is of course 1/2 There is no limitation, and various numerical values such as 1/3 or 1/5 can be taken, and an optimal numerical value is selected according to the measurement situation.

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

  In addition, when a quartic curve or higher is used as the envelope, the curve itself may be used as an envelope, or each of a pair of quartic or higher curves as in the case of the cubic curve described above. A curve connecting peak points may be used as an envelope.

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

  The present invention can take other various forms without departing from the gist thereof.

It is a perspective view explaining the structure of the oscillometric type automatic blood pressure measuring device 8 which is one Example of this invention. It is a block diagram explaining the circuit structure of the Example of FIG. It is a functional block diagram explaining the principal part of the control function of the electronic control apparatus 58 in the Example of FIG. It is a figure which illustrates the cuff pulse wave train in the two-dimensional coordinates of the cuff pressure axis and the cuff pulse wave amplitude axis, and shows the envelope of the cuff pulse wave train. It is a flowchart explaining the principal part of the control action of the electronic control apparatus 58 in the Example of FIG. It is a flowchart which shows the blood-pressure determination routine in the control action of the electronic controller 58 in the Example of FIG. It is a functional block diagram explaining the principal part of the control function of the electronic controller 58 in the other Example of this invention. It is a flowchart which shows the blood-pressure determination routine in the control action | operation of the electronic controller 58 in the Example of FIG.

Explanation of symbols

8: Oscillometric automatic blood pressure measurement device 15: Cuff 82: Blood pressure determination means 86: Cuff pulse wave abnormal value determination means 88: Curve position correction means 90: Envelope determination means

Claims (2)

The amplitude of the cuff pulse wave sequentially generated in synchronization with the pulse of the living body detected through the cuff during the cuff pressure gradual change period in which the compression pressure of the cuff wound around a part of the living body is gradually changed. In an oscillometric automatic blood pressure measurement device comprising blood pressure determining means for determining a blood pressure value of the living body based on a change in the shape of an envelope determined from a change in value,
The amplitude of each cuff pulse wave of the cuff pulse wave train aligned in the cuff pressure axis direction in the two-dimensional coordinates of the cuff pressure axis representing the cuff pressure value and the cuff pulse wave amplitude axis representing the amplitude value of the cuff pulse wave. A connecting curve connecting the upper peak points between the upper peak point and the lower peak point of the pair of cubic curves that minimizes the deviation from the value is obtained. An oscillometric automatic blood pressure measurement device comprising envelope determining means for determining an envelope as an envelope. Cuff pulse wave abnormal value determining means for determining whether or not each of the cuff pulse waves is an abnormal value;
Before the envelope determination means obtains the connection curve, the deviation of the cuff pulse wave determined to be an abnormal value by the cuff pulse wave abnormal value determination means is multiplied by a predetermined abnormal value correction coefficient. The oscillometric automatic blood pressure measuring device according to claim 1, further comprising: curve position correcting means for correcting the position of the connecting curve.

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