JPH10286242A - Blood pressure monitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a blood pressure monitor which can prevent the preparation of a corresponding relationship with a low degree of accuracy and lowering of the accuracy of monitored blood pressure caused thereby. SOLUTION: A means 84 for inhibiting a corresponding relationship from being updated allows a means 76 for updating a corresponding relationship to update a corresponding relationship if a pulse wave transmission time difference (DTRP-DTRP') calculated by a means 82 for calculating a pulse wave transmission time difference is smaller than a preset reference value δ, but inhibits the means 76 from updating the corresponding relationship if the pulse wave transmission time difference (DTRP-DTRP') is greater than the preset reference value δ. Accordingly, if the variation in blood pressure is large in a blood pressure measuring period using pressing by a cuff 10, the updating of a corresponding relationship can be avoided, thereby it is possible to inhibit the preparation of a corresponding relationship with a low degree of accuracy and lowering of accuracy of monitored blood pressures caused thereby.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

As pulse wave velocity information of the pulse wave propagating in the arteries of the Prior Art The biological, are known, such as the propagation time between two predetermined sites DT and the propagation velocity V _M (m / s), such Pulse wave velocity information is a blood pressure value BP of a living body within a predetermined range.
(MmHg). Thus, for a given living body, from a relatively reliable blood pressure value BP measured using a cuff and propagation velocity information obtained from the living body, for example, EBP = α (DT) + β (where α is a negative value ) Or EBP = α (V _M ) + β (where α is a positive value).
And β are determined in advance, based on the pulse wave velocity information that is sequentially detected from the correspondence determined in this manner,
There has been proposed a blood pressure monitoring device that continuously obtains an estimated blood pressure value EBP and monitors a blood pressure value of a living body. According to this device, blood pressure monitoring can be performed for a predetermined period without imposing a load due to pressure on the cuff. For example, Japanese Patent Laid-Open No. 7-
That is the blood pressure monitoring device described in Japanese Patent No. 31593.

In the blood pressure monitoring device as described above, a correspondence is created based on a blood pressure value measured using a cuff for a predetermined living body and pulse wave propagation velocity information obtained from the living body. In order to maintain the accuracy of blood pressure, it is necessary to increase the accuracy of creating the correspondence itself.

[0004]

By the way, the above-mentioned conventional blood pressure monitoring device is provided with a correspondence updating means for determining and updating the correspondence at a relatively long cycle set in advance. Blood pressure measurement is performed using cuff compression, which is relatively reliable, and the correspondence is determined based on blood pressure values obtained thereby and pulse wave propagation velocity information obtained immediately before the start of compression by the cuff. It had been.
However, the blood pressure measurement using the cuff pressure is about 30 minutes.
Since a relatively long measurement time of about seconds is required, the blood pressure value of the living body may keep changing within the measurement time. In such a case, there is a problem that a low-precision correspondence is created, and the accuracy of the monitored blood pressure cannot be obtained.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to create a low-precision correspondence and to prevent a decrease in monitoring blood pressure accuracy due to the correspondence. It is to provide a device.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the gist of the present invention is to provide a blood pressure value of a living body based on a change in a pulse synchronizing wave generated in a process in which a compression pressure of a cuff is changed. Blood pressure measurement means for measuring the pulse wave propagation velocity information related to the pulse wave propagation velocity in the artery of the living body, and pulse wave propagation velocity information calculation means for sequentially computing the pulse wave propagation velocity information. Based on the obtained pulse wave propagation speed information and the blood pressure value measured by the blood pressure measuring means, the correspondence between the pulse wave propagation speed information and the blood pressure value is determined at a predetermined cycle, and the correspondence is updated. A corresponding relationship updating unit, and an estimated blood pressure value of the living body based on the actual living body pulse wave propagation speed information sequentially calculated by the pulse wave propagation speed information calculating unit from the correspondence updated by the corresponding relationship updating unit. A blood pressure monitoring device of a type comprising: an estimated blood pressure value determining means for sequentially determining, wherein (a) pulse wave propagation speed information for calculating said pulse wave propagation speed information difference before and after a blood pressure value measurement period by said blood pressure measuring means. And (b) updating the correspondence by the correspondence updating means when the pulse wave propagation speed information difference calculated by the pulse wave propagation speed information difference calculating means is smaller than a predetermined reference value. However, if the pulse wave propagation velocity information difference is larger than the determination reference value, a correspondence update prohibition unit that prohibits the update of the correspondence is included.

[0007]

In this way, when the pulse wave propagation speed information difference calculated by the pulse wave propagation speed information difference calculating unit is smaller than the predetermined criterion value by the correspondence updating update prohibiting unit, Updating of the correspondence by the correspondence updating means is permitted, but when the pulse wave propagation velocity information difference is larger than the judgment reference value, the update of the correspondence is prohibited. Therefore, when the blood pressure change is large during the blood pressure measurement period using the cuff compression, the updating of the correspondence is avoided, so that the creation of the correspondence with low accuracy and the decrease in the monitoring blood pressure accuracy caused by the correspondence are prevented. You.

[0008]

Preferably, the pulse wave velocity information calculating means calculates the pulse wave velocity information in synchronization with the generation of the pulse wave, and simultaneously calculates the pulse wave velocity information. The pulse wave propagation velocity information is calculated by calculating a moving average value of the pulse wave propagation velocity information obtained in relation to a predetermined number of pulse waves before that. If you do this,
There is an advantage that the influence on noise caused by body movement of a living body is reduced.

[0009] Preferably, the correspondence relation determining means is provided during a period from the start of the compression of the cuff to the time when the compression pressure reaches the average blood pressure value, more preferably, the compression pressure P
Immediately before _C reaches the average blood pressure value, the pulse wave propagation speed information calculated by the pulse wave propagation speed information calculation unit and the blood pressure value measured by the blood pressure measurement unit in relation to the compression by the cuff are calculated. Based on this, the correspondence is determined. By doing so, there is an advantage that the time difference from the blood pressure value determined after the start of the cuff compression is reduced, and the accuracy of the correspondence is appropriately increased.

[0010] Preferably, the pulse wave propagation velocity information difference calculating means is obtained at the time of starting the cuff compression by the blood pressure measuring means and at the end of the cuff compression. The difference from the pulse wave propagation velocity information is calculated. With this configuration, since the pulse wave propagation velocity information at the time when the cuff is not compressed and the blood pressure measurement period is approached is used, there is no influence of the pulse wave deformation due to the cuff compression, and the blood pressure change during the blood pressure measurement period is not affected. The accuracy of the presence / absence determination is improved.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram illustrating a configuration of a blood pressure monitoring device 8 to which the present invention has been applied.

In FIG. 1, a blood pressure monitoring device 8 has a rubber bag in a cloth band-shaped bag.
And a pressure sensor 14, a switching valve 16, and a cuff 10 connected to the cuff 10 via a pipe 20, respectively.
And an air pump 18. This switching valve 16
The three states are a pressure supply state in which the supply of the pressure into the cuff 10 is allowed, a slowly changing state in which the pressure in the cuff 10 is gradually increased or decreased, and a rapid exhaust state in which the pressure in the cuff 10 is rapidly exhausted. It is configured to be switchable.

The pressure sensor 14 detects the pressure in the cuff 10 and outputs a pressure signal SP representing the pressure to the static pressure discriminating circuit 2.
2 and the pulse wave discrimination circuit 24. Static pressure filter circuit 22 includes a low pass filter, the cuff pressure signal SK via the A / D converter 26 and discriminating the cuff pressure signal SK representative of a steady pressure or cuff pressure P _C is included in the pressure signal SP It is supplied to the electronic control unit 28. Pulse-wave filter circuit 24 includes a band-pass filter, the cuff-pulse-wave signal SM ₁ through the A / D converter 30 and discriminating the cuff-pulse-wave signal SM ₁ which is an oscillating component of the pressure signal SP in frequency electronic It is supplied to the controller 28. This cuff pulse wave signal SM ₁
Represents a pressure vibration wave generated from a brachial artery (not shown) and transmitted to the cuff 10 in synchronization with the heartbeat of the patient.

The electronic control unit 28 includes a CPU 29, R
The microcomputer 29 includes a so-called microcomputer including an OM 31, a RAM 33, an I / O port (not shown), and the like. The CPU 29 executes signal processing using a storage function of the RAM 33 according to a program stored in the ROM 31 in advance. Thus, a drive signal is output from the I / O port to control the switching valve 16 and the air pump 18.

The electrocardiographic lead device 34 applies a first signal generated from the living body in connection with the contraction of the heart of the living body, that is, an electrocardiogram, which indicates the action potential of the myocardium, a so-called electrocardiogram to a predetermined portion of the living body. A signal SM ₂ (first signal) indicating the electrocardiographically induced wave is continuously detected through the plurality of electrodes 36 to be applied, and is output to the electronic control unit 28. Since the electrocardiographic lead device 34 is for detecting an R wave or the like among the electrocardiographic lead waves corresponding to the time when the blood in the heart starts pumping toward the aorta, the first It functions as a pulse wave detector.

Photoelectric pulse wave detection probe for pulse oximeter
The probe 38 (hereinafter simply referred to as a probe) includes a capillary.
The pulse wave transmitted to the peripheral artery
_RAnd SM_IRSecond signal detecting device for outputting (second signal)
Functioning as a stationary or peripheral pulse wave detection means,
For example, a portion on the peripheral side of the cuff 10 of the subject, for example,
Not shown on living skin such as fingertips, that is, body surface 40
It is worn in close contact with a wearing band or the like. Step
The lobe 38 is a container-shaped housing opened in one direction.
Ring 42 and the outer peripheral side of the inner surface of the bottom of the housing 42.
A plurality of first sensors, such as LEDs,
Light emitting element 44_aAnd the second light emitting element 44 _b(Below, especially
If no distinction is made, it is simply referred to as light emitting element 44).
Provided at the center of the bottom inner surface of the
Light receiving element 46 composed of an diode and a phototransistor
And the light emitting element 4 provided integrally in the housing 42.
A transparent resin 48 covering the light receiving element 4 and the light receiving element 46;
Between the light emitting element 44 and the light receiving element 46 in the
From the light emitting element 44 toward the body surface 40
From the body surface 40 of the illuminated light to the light receiving element 46
And an annular shielding member 50 for shielding reflected light.
Have been.

[0017] The first light-emitting element 44 _a, for example 660
The second light emitting element 44 _b emits red light having a wavelength of about
Emits infrared light having a wavelength of about 880 nm, for example. The first light-emitting element 44 _a and the second light emitting element 44 _b, together are caused to emit light at a predetermined frequency for a predetermined time at a time order, from their light-emitting element 44 in the body of the light emitted toward the body surface 40 capillaries The reflected light from the area where the light is densely received is received by the common light receiving element 46. The wavelength of light emitted of the light emitting element 44 is not limited to the above values, the light absorption coefficient significantly different wavelength from the first light emitting element 44 _a is reduced oxyhemoglobin hemoglobin, the second light emitting element 44 _b is Any wavelength may be used as long as it emits light having a wavelength at which the extinction coefficients thereof are substantially the same, that is, light having a wavelength reflected by oxyhemoglobin and reduced hemoglobin.

The light receiving element 46 outputs a photoelectric pulse wave signal SM ₃ having a magnitude corresponding to the amount of received light via a low-pass filter 52. An amplifier and the like are appropriately provided between the light receiving element 46 and the low-pass filter 52. Low pass filter 52 removes noise from the photoelectric pulse-wave signal SM ₃ input has a higher frequency than the frequency of the pulse wave, and outputs a signal SM ₃ whose noise has been removed to a demultiplexer 54. The photoelectric pulse wave represented by the photoelectric pulse-wave signal SM ₃ is a volume pulse wave generated in synchronism with the patient's pulse rate. In addition, this photoelectric pulse wave corresponds to a pulse synchronization wave.

The demultiplexer 54 is connected to the electronic control unit 2
By being switched in synchronization with the emission of the first light-emitting element 44 _a and the second light emitting element 44 _b according to a signal from 8, sample and hold circuit photoelectric pulse-wave signal SM _R due to the red light 56 and the A / D converter 58 through, the photoelectric pulse-wave signal SM _IR due to the infrared light through a sample-and-hold circuit 60 and a / D converter 62, respectively electronic control unit 28
Are sequentially supplied to an I / O port (not shown). The sample-and-hold circuits 56 and 60 receive the input photoelectric pulse wave signal SM
When outputting _R and SM _IR to A / D converters 58 and 62,
A for the previously output photoelectric pulse wave signals SM _R and SM _IR
By the time the conversion operation in the / D converters 58 and 62 is completed, the photoelectric pulse wave signals SM _R and SM _IR to be output next are respectively held.

The CPU 29 of the electronic control unit 28 has a RAM
The measurement operation is performed according to a program stored in the ROM 31 in advance while utilizing the storage function of the drive circuit 64.
Emitting element 44 outputs a control signal SLV to _a, 44 one for sequentially for a predetermined time increments emission at a predetermined frequency _b, their light-emitting element 44 _a, 44 _b switching signal S in synchronization with the emission of
By outputting C and switching the demultiplexer 54, the photoelectric pulse wave signal SM _R is supplied to the sample hold circuit 56, and the photoelectric pulse wave signal SM _IR is _supplied to the sample hold circuit 6.
Distribute each to 0. The CPU 29 calculates the blood oxygen saturation of the living body based on the amplitude values of the _{photoplethysmographic} signals SM _R and SM _IR from an arithmetic expression stored in advance to calculate the blood oxygen saturation. As a method of determining the oxygen saturation, for example, a determination method described in Japanese Patent Application Laid-Open No. H3-15440, which was previously filed by the present applicant, is used.

FIG. 2 shows an electronic device in the blood pressure monitoring device 8.
Functional block for explaining a main part of the control function of control device 28
FIG. In FIG. 2, the blood pressure measuring means 70 includes a cuff.
For example, it is wound around the upper arm of a living body by the pressure control means 72.
Compression pressure P of cuff 10_CIs a predetermined target pressure value P_M1(T
For example, the pressure was raised to 180mmHg).
Slow down pressure that is gradually reduced at a speed of about 3 mmHg / sec later
Cuff pulse signal SM sequentially collected during the pressure period₁ 
Well-known oscilloscope based on changes in pulse wave amplitude
Systolic blood pressure BP using the trick method_SYSAnd diastolic blood pressure
Value BP_DIADecide etc. For example, the above blood pressure measurement hand
Stage 70 has increased amplitude during the slow buck period.
The point where the maximum value of the pulse wave amplitude difference that decreases later occurs.
The cuff pressure at the inflection point of the envelope connecting the pulse wave amplitudes to systolic blood pressure
Value BP_SYSAnd diastolic blood pressure BP _DIADetermined as a pulse
The cuff pressure at the point where the maximum value of the wave amplitude occurs is calculated as the average blood pressure value BP
_{ME AN}To be determined.

The pulse wave propagation velocity information calculating means 74 uses a probe 38 from a predetermined portion, for example, an R-wave, which is generated at each cycle of the electrocardiographically guided wave sequentially detected by the electrocardiographically guiding device 34 as shown in FIG. A time difference (pulse wave propagation time) DT _RP to a predetermined portion, for example, a rising point or a maximum inclination point, which is generated in each cycle of the photoplethysmogram sequentially detected is sequentially calculated for each pulse.

The correspondence relationship updating means 76 provides the pulse wave propagation velocity information calculating means 7 during a period in which the compression pressure is lower than the average blood pressure value BP _MEAN during the compression period by the cuff 10.
4 based on the pulse wave propagation speed information calculated in step 4, ie, the pulse wave propagation time DT _RP and the blood pressure value measured by the blood pressure measuring means 70 in relation to the compression by the cuff 10, for example, the systolic blood pressure value BP _SYS . 4 is determined at a predetermined cycle of about 15 to 20 minutes, which is sufficiently longer than the pulse wave propagation velocity information calculation cycle or the blood pressure value estimation cycle, and is newly determined based on the previously used correspondence. Update to the specified correspondence. That is, as shown in FIG.
If the 0 of the compression pressure P _C is changed, the even after the predetermined number of beats has elapsed since the compression starting point, the pressing pressure P
_The blood pressure measuring means 70 is associated with the pulse wave transit time DT _RP calculated during the period before _C reaches the average blood pressure value BP _MEAN , for example, immediately before reaching the average blood pressure value BP _MEAN , and the compression by the cuff 10 thereof. Blood pressure value B measured by
The correspondence as shown in FIG. 4 is determined based on P _SYS . The photoelectric pulse wave signal shown in the upper part of FIG.
The photoplethysmographic detection probe 3 is located on the distal side of the arm
8 shows a waveform when the cuff 10 is attached, and its amplitude is reduced with the compression by the cuff 10.

For example, the correspondence updating means 76
Systolic blood pressure value BP measured by blood pressure measuring means 70_SYS
And the average blood pressure value within the cuff compression period of the blood pressure measurement
BP _MEANPulse transit time DT just before arriving at_RPAnd that
Pulse wave transit time DT determined before_RPThe predetermined number of beats period
Based on the moving average of the pulse wave
Time DT_RPAnd systolic blood pressure BP_SYSIn the relational expression with
The numbers α and β are determined in advance.

[0025]

EBP = α (DT _RP ) + β (1) (where α is a negative constant and β is a positive constant)

The estimated blood pressure value determining means 78, the relationship between the blood pressure value of the living and the pulse-wave propagation time DT _RP of the living from (Equation 1), is sequentially calculated by the pulse-wave-propagation information obtaining means 74 An estimated systolic blood pressure value EBP _SYS is sequentially determined for each pulse based on the actual pulse wave transit time DT _RP of the living body,
The estimated systolic blood pressure value EBP is displayed on the display device 32 in a trendable manner along a predetermined time axis.

The cuff measurement activating means 80 performs the blood pressure measurement by the blood pressure measuring means 70 on the basis of the fact that the estimated systolic blood pressure value EBP _SYS determined by the estimated blood pressure value determining means 78 exceeds a predetermined judgment reference value. Start. That is, the cuff measurement activating unit 80 sets the estimated blood pressure value determining unit 78
The estimated systolic blood pressure value EBP _SYS determined by the above is determined to be abnormal based on a predetermined reference value, for example, when the blood pressure measurement unit 70 has changed from the previous blood pressure measurement by the previous cuff by a predetermined value or a predetermined ratio or more. It also functions as a value abnormality judging means, and activates the blood pressure measurement by the blood pressure measuring means 70, for example, when the blood pressure measuring means 70 changes by 20% or more with respect to the previous blood pressure measurement by the cuff.

The pulse wave propagation speed information difference calculating means 82 calculates the difference (change amount) of the pulse wave propagation speed information corresponding to the blood pressure fluctuation amount before and after the blood pressure measurement operation by the blood pressure measuring means 70, for example, the measurement of the blood pressure value. 'the difference between | DT _RP -DT _RP' | wave propagation time DT _RP immediately after the measurement operation of the pulse-wave propagation time DT _RP and its blood pressure value in the operation immediately before is calculated. If the pulse wave propagation speed information difference | DT _RP −DT _RP ′ | calculated by the pulse wave propagation speed information difference calculation unit 82 is smaller than the predetermined judgment reference value δ, Updating of the correspondence by the correspondence updating means 76 is permitted, but the pulse wave propagation velocity information difference | D
If T _RP −DT _RP ′ | is larger than the criterion value δ, the update of the correspondence is prohibited. The determination reference value δ is a value experimentally set in advance in order to determine that the blood pressure change amount during the blood pressure measurement period is large and is inappropriate for determining the correspondence.

FIG. 6 is a flowchart for explaining a main part of the control operation in the electronic control unit 28 of the blood pressure monitoring device 8. In FIG. 6, after an initial process of clearing a flag, a counter, and a register (not shown) is performed in step SA1 (hereinafter, steps are omitted), an estimated blood pressure is calculated in SA2 corresponding to the correspondence updating unit 76. In order to update the base correspondence, for example, a correspondence determination routine shown in FIG. 7 is executed. In FIG. 7, the blood pressure measurement using the cuff 10 for determining the correspondence is performed during the slow down period.

[0030] In SC1 of FIG. 7, the switching valve 16 is switched and the air pump 18 to a pressure supply state quickly increasing the cuff pressure P _C is started by being driven. T in FIG.
₁ indicates the time. Next, in SC2, the cuff pressure P _C
Is determined to be equal to or less than a predetermined average blood pressure value BP _MEAN . This average blood pressure value BP _MEAN is an upper limit value at which the photoelectric pulse wave is not distorted by the compression of the cuff, and may be a statistically set constant value, but was measured in the previous correspondence determination routine. It may be a value. Initially, since the judgment of SC2 is denied, in SC3 corresponding to the pulse wave propagation velocity information calculating means 74, a predetermined portion generated in each cycle of the electrocardiographic guided wave sequentially detected by the electrocardiographic guiding device 34 For example, from the R wave, the probe 38
The time difference (pulse wave propagation time) DT _RP to a predetermined portion generated in each cycle of the photoelectric pulse wave sequentially detected by the above, for example, a rising point, an upper peak point, or a maximum inclination point is within a predetermined number of beats before that. Is calculated and stored as the moving average value of

[0031] Then, in SC4, whether the cuff pressure P _C reaches the preset target pressing pressure P _M1 or higher is determined. This target compression pressure P _M1 is a value set sufficiently higher than the systolic blood pressure of the living body, and is set, for example, to a value of about 180 mmHg. Initially, the determination of SC4 is denied, so that SC1 and subsequent steps are repeatedly executed.

[0032] Among executed repeatedly above steps, the determination of the SC2 is positive by exceeding the mean blood pressure value BP _MEAN the cuff pressure P _C is set in advance, S
C3 is so that SC4 without being executed is executed, even within the period cuff pressure P _C is equal to or less than the mean blood pressure value BP _MEAN, immediately before the cuff pressure P _C reaches the mean blood pressure BP _MEAN The pulse wave transit time DT _{RP is} determined as a moving average of the pulse wave transit time and the pulse wave transit time within a period of a predetermined number of beats before the pulse wave transit time.
Are stored in SC3.

[0033] Then, among the above steps is further repeatedly executed, when the cuff pressure P _C is determined in SC4 reached the target compression pressure P _M1 is positive, the switching valve with the air pump 18 is stopped at SC5 by 16 is switched to the slow change in state is caused to slow decreasing at a pre-set speed of the cuff pressure P _C is for example, about 3 mmHg / sec. T ₂ in FIG. 5 shows the time.

[0034] Then, in SC6, whether the cuff pulse wave has occurred is determined based on the cuff pulse-wave signal SM _1. While the determination of SC6 is denied, the above-described steps SC5 and below are repeatedly executed. If the determination is affirmed, a blood pressure determination routine for determining a blood pressure value by an oscillometric method is executed in SC7, and then in SC8. It is determined whether the blood pressure determination is completed by executing the blood pressure determination routine.

Initially, the number of cuff pulse waves generated is not sufficient.
In addition, since the judgment of SC8 is denied,
It is executed repeatedly. And the above steps are repeated
While being executed, systolic blood pressure value BP_SYS, Mean blood pressure value BP
_MEAN, And diastolic blood pressure BP _DIAAre all determined
When the blood pressure determination is completed, the judgment of SC8 is affirmed.
In SC9, the switching valve 16 is released to the pressure released state.
The cuff 10 is quickly released by being switched,
Note systolic blood pressure BP_SYS, Mean blood pressure value BP_MEAN, And most
Low blood pressure BP_DIAIs displayed on the display 32. T in FIG.
_ThreeIndicates the time. In this embodiment, SC9 and
The SC1, SC4 and SC5 correspond to the cuff pressure control means 7.
2 is supported.

Subsequently, the pulse wave propagation velocity information calculating means 7
In the SC 10 corresponding to 4, the pulse wave propagation time information DT _RP ′, which is the pulse wave propagation velocity information immediately after the completion of the blood pressure measurement, is calculated in the same manner as described above, and then corresponds to the pulse wave propagation velocity information difference calculation means 82. In SC11, the difference between the pulse wave propagation speed information difference corresponding to the blood pressure fluctuation amount, for example, the pulse wave propagation time DT _RP immediately before the blood pressure value measurement operation and the pulse wave propagation time DT _RP 'immediately after the blood pressure value measurement operation | DT
_RP -DT _RP '| is calculated.

Then, at SC12 corresponding to the correspondence update prohibiting means 84, the pulse wave transit time difference | DT _RP -DT _RP '| calculated at SC11 is equal to or larger than a predetermined judgment reference value δ. Is determined. This determination criterion value δ is a value for determining that the amount of change in blood pressure during the blood pressure measurement period is large and inappropriate for determining the correspondence.

If the pulse wave transit time difference | DT _RP −DT _RP ′ | corresponding to the blood pressure fluctuation amount before and after the blood pressure measurement period is smaller than the judgment reference value δ, the judgment of SC12 is denied, and the correspondence relationship is determined. SC13 corresponding to updating means 76
Is allowed. Therefore, in SC13, based on the systolic blood pressure value BP _SYS determined in SC7 and the pulse wave transit time DT _RP stored in SC3,
The correspondence shown in Equation 1 is newly determined, and the correspondence up to that time is updated to the newly determined correspondence.

However, the pulse wave transit time difference | DT _RP -D
If T _RP ′ | is equal to or greater than the criterion value δ, the SC
When the determination in step 12 is affirmed and the execution of SC 13 is avoided, the update of the correspondence is prohibited.

When the correspondence is re-determined and updated as described above, SA3 and subsequent steps in FIG. 6 are executed. SA
At 3, it is determined whether or not the R wave of the electrocardiographic waveform and the photoelectric pulse wave have been input. If the determination at SA3 is denied, SA3 is repeatedly executed. If the determination is affirmed, at SA4 corresponding to the pulse wave propagation velocity information calculating means 74, the R wave of the newly input electrocardiographic waveform is obtained. And the pulse wave propagation time DT _RP for the photoelectric pulse wave is calculated.

[0041] In SA5 corresponding to the estimated blood-pressure determining means 78, the correspondence between the propagation time and the blood pressure determined at the SA2, based on the pulse wave propagation time DT _RP obtained in the above SA4, estimated highest Hypertension E
BP _SYS is determined and the estimated systolic blood pressure value EB per beat
P _SYS is output to the display 32 in order to display a trend.

Next, in SA6 corresponding to the cuff measurement activation means 80, for example, the estimated blood pressure value EBP is set, for example, to a judgment reference range set to about 20 to 25% above and below the value at the time of the previous cuff measurement. The blood pressure measurement by the blood pressure measurement means 70 (SC7, SC8) is activated based on the fact that the blood pressure has been exceeded. If the determination at SA6 is negative, SA7 is executed. In SA7, it is determined whether or not the elapsed time from the blood pressure measurement by the cuff 10 in SA2 has passed a preset cycle of about 15 to 20 minutes, that is, a calibration cycle. If the determination at SA7 is denied, the SA
The blood pressure monitoring routine of 3 or less is repeatedly executed, the estimated systolic blood pressure value EBP _SYS is continuously determined for each beat, and the determined estimated systolic blood pressure value EBP _SYS is displayed on the display 32.
Are displayed in a chronological trend. However, if the determination in SA7 is affirmed, the cuff calibration routine for SA2 and below is executed again to re-determine the correspondence.

However, if the determination at SA6 is affirmative, an abnormal display of the estimated systolic blood pressure value EBP _SYS is displayed on the display 32 at SA8, and then the steps below SA2 are executed again to determine the correspondence again. Then, the blood pressure measurement by the cuff 10 is started.

As described above, according to this embodiment, the pulse wave propagation time difference | DT _RP −DT calculated by the pulse wave propagation velocity information difference calculating means 82 (SC 11) by the correspondence update inhibiting means 84 (SC 12). _{If RP} ′ | is smaller than the preset judgment reference value δ, the correspondence updating unit 76 (SC
13), the update of the correspondence is prohibited when the pulse wave transit time difference | DT _RP −DT _RP '| is larger than the criterion value δ. Therefore, when the blood pressure change is large within the blood pressure measurement period using the compression of the cuff 10, for example, the update of the correspondence shown in FIG. 4 is avoided, so that a low-precision correspondence is created and the monitoring blood pressure resulting therefrom is reduced. A decrease in accuracy is prevented.

Further, according to the present embodiment, the pulse wave propagation speed information calculating means 74 (SA4) sequentially calculates the pulse wave propagation time DT _RP in synchronization with the generation of the pulse wave, and calculating means 74 (SC3), the corresponding relationship by obtaining the moving average of the pulse wave propagation time DT _RP obtained in relation to the calculated pulse wave propagation time DT _RP and previous predetermined number of pulse wave _Is to calculate the pulse wave transit time DT _RP which is the basis of In this way, there is an advantage that the influence on noise caused by body movement of the living body is reduced.

[0046] Further, according to this embodiment, the correspondence relationship updating unit 76 (SC13) is within the period from the compression starting point of the cuff 10 until the pressing pressure P _C reaches the mean blood pressure value BP _MEAN, more preferably pressing pressure P _C in the mean blood pressure BP
Immediately before reaching _MEAN , the pulse wave propagation time D calculated by the pulse wave velocity information calculation means 74 (SC3)
Since the correspondence is determined based on the T _RP and the blood pressure value measured by the blood pressure measuring means 70 (SC7, SC8) in relation to the compression by the cuff 10, the cuff 1
There is an advantage that the time difference from the blood pressure value determined after the start of the compression of 0 is reduced, and the accuracy of the correspondence is appropriately increased.

Further, according to the present embodiment, the pulse wave propagation velocity information difference calculating means 82 (SC11)
The difference between the pulse wave propagation time DT _RP obtained at the start of compression of the cuff 10 by (SC7, SC8) and the pulse wave propagation time DT _RP ′ obtained at the end of compression of the cuff 10 is calculated. Therefore, the pulse wave transit times DT _RP , D at the time of deviating from the compression period of the cuff 10 that substantially distorts the pulse wave and approaching the blood pressure measurement time as close as possible.
Since T _RP ′ is used, even when the cuff 10 and the photoelectric pulse wave detection probe 38 are provided on the same arm, the pulse wave propagation caused by the deformation of the pulse wave due to the compression of the cuff 10 The accuracy of the times DT _RP and DT _RP ′ does not decrease, and the accuracy of determining the presence or absence of a blood pressure change during the blood pressure measurement period is improved.

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

For example, in the embodiment of FIG.
It had been described for the case of creating a correspondence between estimated blood pressure and the pulse wave propagation time DT _RP, and correspondence between the estimated blood pressure and the pulse wave propagation velocity V _M (pulse wave velocity information) is created No problem. In this case, the horizontal axis is the characteristic of the upward-sloping become axis indicating the pulse-wave propagation velocity V _M in FIG. At this time, the pulse wave propagation velocity information calculating means 74
Calculates the propagation velocity V _M (m / sec) of the pulse wave propagating in the artery of the subject based on the time difference | DT _RP −DT _RP ′ | In Equation 2, L (m) is the distance from the left ventricle to the site where the probe 38 is mounted via the aorta, and T _PEP
(Sec) is a pre-ejection period from the R wave of the electrocardiographic lead waveform to the rising point of the aortic root pulse wave. The distance L and the pre-ejection period T _PEP are constants, and values experimentally obtained in advance are used. The correspondence updating means 7
6 is the systolic blood pressure value B measured by the blood pressure measuring means 70
P _SYS and cuff pressure P _C within each cuff compression period
Is a pulse wave velocity V _M within a period of time equal to or less than the average blood pressure value,
For example based on the average value of the pulse wave propagation velocity V _M within that period, the coefficients α and β in relation to the propagation velocity V _M and the systolic blood pressure value BP _SYS represented by formula 3, is predetermined.

[0050]

[Number 2] _{V M = L / (DT RP} -T PEP) ··· (2)

[0051]

EBP _SYS = α (V _M ) + β (3) (where α is a positive constant and β is a positive constant)

Further, in SC13 for obtaining the correspondence shown in the above-mentioned equations (1) and (3), the systolic blood pressure value BP is obtained.
Instead of _SYS , the average blood pressure value BP _MEAN or the diastolic blood pressure value BP _DIA measured by the blood pressure measuring means 70 and the pulse wave propagation time DT _RP or the pulse wave velocity V during the cuff compression period.
A relationship with _M may be required. In short, the selection is made based on whether the monitored (estimated) blood pressure value EBP is a systolic blood pressure value, an average blood pressure value, or a diastolic blood pressure value.

[0053] Also, including in the illustrated embodiment, the SC11 corresponding to the pulse-wave-velocity-related information difference calculation unit 82, a pulse-wave propagation time DT _RP immediately before the cuff pressure P _C reaches the mean blood pressure BP _MEAN moving average has been used, but to the cuff pressure P _C is no problem even if used only the value immediately before reaching the mean blood pressure BP _{ME AN} is, the cuff pressure P _C increased beginning or before than that of The pulse wave transit time DT _RP may be used. Also, the pulse wave propagation time DT after the blood pressure measurement operation
_RP 'not only t ₃ time points after completion blood pressure measurement, or may be detected after a predetermined time than that time. In short, it is only necessary to be able to grasp the blood pressure fluctuation within the blood pressure measurement period.

[0054] Further, FIG. 7 of the above-described embodiment shows an example in determining the blood pressure measurement cuff pressure P _C is a blood pressure determined by the process to be allowed to slow decreasing from being raised higher than the systolic blood pressure is carried out those in which was, but in the process of the cuff pressure P _C is caused to Josoku boosted after being quickly increased to a value of diastolic blood pressure just under the biological, the blood pressure determination algorithm is executed, the cuff 10 is rapidly released when the blood pressure determination is completed A so-called step-up measurement of a type that can be recognized may be used.

Further, in the above-described embodiment, the correspondence shown in Expression 1 or Expression 3 has been described using a linear expression. However, a polynomial expression such as a quadratic expression may be used.

Further, the blood pressure measuring means 70 of the above-described embodiment is used.
Is configured to measure blood pressure by a so-called oscillometric method, but the cuff pressure at the time of occurrence and disappearance of Korotkoff sound, which is a signal wave generated from an artery in synchronization with a pulse, is determined by a systolic blood pressure value and a diastolic blood pressure. The blood pressure may be measured by a so-called K-tone method determined as a value.

In the above-described embodiment, the reflection type photoelectric pulse wave detecting probe 38 is used as the second signal detecting means, that is, the peripheral pulse wave detecting means. For example, a tonometry sensor that is pressed by the radial artery to detect a pressure pulse wave, an impedance pulse wave detection device that detects a change in impedance through an electrode attached to a finger, and an internal pressure that is pressed by the radial artery Pulse wave detecting device for detecting the pressure, a cuff 10 holding a predetermined pressure
A cuff pulse wave sensor that detects a cuff pulse wave from the sensor may be used. In short, it only needs to detect a pulse wave that has propagated through an artery in a peripheral part of a living body.

In the above-described embodiment, the electrocardiograph 3
The pulse wave propagation time DT _RP or the pulse wave propagation is determined based on the time difference between the R wave, which is a predetermined part of the electrocardiographic waveform detected by step 4, and the predetermined part of the photoelectric pulse wave detected by the photoelectric pulse wave detection probe 38. velocity V _M has been demanded, but is attached to the distal portion such as the first signal detection means and the wrist or fingers, such as the cuff for detecting the mounted on the carotid pulse wave sensor or the brachial artery to press the carotid artery pulse wave pulse-wave propagation time DT _RP or the pulse wave propagation velocity V _M between the second signal detector may also be obtained.

In the above-described embodiment, the pulse wave propagation time DT _RP is calculated based on the time difference from the R wave to the rising point of the photoelectric pulse wave. Other calculation methods such as using a time difference up to the rising point are used.

In the above-described embodiment, the blood pressure is monitored for each beat of the R wave or the photoelectric pulse wave. However, the blood pressure may be monitored for every two or more beats.

When the probe 38 is attached to a portion different from the downstream portion of the arm to which the cuff 10 is attached, the distortion of the photoelectric pulse wave due to the compression of the cuff 10 does not occur. SC2 may be removed.

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

[Brief description of the drawings]

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

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

FIG. 3 is a diagram illustrating a time difference DT _RP obtained by a control operation of the electronic control device 28 in the embodiment of FIG. 1;

FIG. 4 is a diagram showing a correspondence determined by a correspondence determination unit of FIG. 3;

5 is a time chart showing a change in cuff pressure controlled by the cuff pressure control means in FIG. 2 when measuring blood pressure.

FIG. 6 is a flowchart illustrating a main part of a control operation of the electronic control device in the embodiment of FIG. 1, and is a diagram illustrating a blood pressure monitoring routine.

7 is a flowchart illustrating a main part of a control operation of the electronic control device 28 in the embodiment of FIG. 1, and is a diagram illustrating a correspondence determination routine.

[Explanation of symbols]

 10: Cuff 70: Blood pressure measurement means 74: Pulse wave propagation speed information calculation means 76: Correspondence update means 78: Estimated blood pressure value determination means 82: Pulse wave propagation velocity information difference calculation means 84: Correlation update prohibition means

Claims (1)

[Claims] 1. A blood pressure measuring means for measuring a blood pressure value of a living body based on a change in a pulse synchronizing wave generated in a process in which a compression pressure of a cuff is changed, wherein the blood pressure measuring means relates to a pulse wave propagation velocity in an artery of the living body. Pulse wave propagation speed information calculating means for sequentially calculating pulse wave propagation speed information, based on the pulse wave propagation speed information calculated by the pulse wave propagation speed information calculating means and the blood pressure value measured by the blood pressure measuring means A correspondence updating means for determining the correspondence between the pulse wave propagation velocity information and the blood pressure value at a predetermined cycle and updating the correspondence, and the correspondence updated from the correspondence updated by the correspondence updating means. An estimated blood pressure value determining means for sequentially determining an estimated blood pressure value of the living body based on the pulse wave velocity information of the actual living body sequentially calculated by the wave propagation speed information calculating means. Pulse wave velocity information difference calculating means for calculating the pulse wave velocity information difference before and after the blood pressure measurement operation by the blood pressure measuring means; pulse wave velocity information calculated by the pulse wave velocity information difference calculating means If the difference is smaller than a predetermined criterion value, updating of the correspondence by the correspondence updating means is permitted, but if the pulse wave propagation velocity information difference is larger than the criterion value, the correspondence is updated. A blood pressure monitoring device comprising: