JPH1043148A - Blood pressure monitoring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high accuracy in blood pressure monitoring by correcting the previously set relation between a measured blood pressure and the pulse wave propagation speed information of a living body based on the heart rate calculated by a heart rate calculating means. SOLUTION: Based on the peak blood pressure value measured by a blood pressure measuring means 70 and the average value of pulse wave propagation time or pulse wave propagation speed within a blood pressure measuring period, a correspondent relation determining means 76 determines a coefficient in the relational expression between the pulse wave propagation time or propagation speed and the peak blood pressure value. Based on the real pulse wave propagation time or propagation speed of the living body successively calculated by a pulse wave propagation information calculating means 74, an estimated blood pressure value determining means 78 successively determines estimated blood pressure values and displays the trend of these estimated blood pressure values along a common time base on a display 32 together with their heartbeat cycle and pulse wave area so as to compare them. A heart rate calculating means 90 calculates the heart rate of the living body and based on the heart rate of the living body, a relation correcting means 92 corrects the relation determined by the correspondent relation determining means 76.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blood pressure monitoring device for monitoring a blood pressure of a living body based on pulse wave 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). Therefore, from the blood pressure value BP and the propagation velocity speed information of a living body to be measured in advance, for example, EBP = α (DT) + β ( where a negative value alpha), or _{EBP = α (V M) +} β ( where alpha is a positive ) In the relational expression represented by the following formula, and based on the relational expression, the estimated blood pressure value EBP is obtained based on the sequentially detected propagation velocity information to monitor the blood pressure value of the living body. A blood pressure monitoring device that activates blood pressure measurement using a cuff when the estimated blood pressure value EBP is abnormal has been proposed.

[0003]

The relationship between the blood pressure value of the living body and the pulse wave propagation speed information changes under the influence of central circumstance such as the state of the myocardium. It is necessary to set the criterion value for judging abnormality of the estimated blood pressure value to a value sufficiently distant from the normal blood pressure value in order to increase the blood pressure. In some cases, the start-up was delayed and blood pressure monitoring accuracy was not always sufficiently obtained.

The present invention has been made in view of the above circumstances, and an object of the present invention is to monitor a blood pressure value of a living body based on information on a velocity of a pulse wave propagating in an artery of the living body. It is an object of the present invention to obtain a high blood pressure monitoring accuracy in a blood pressure monitoring device.

[0005]

The inventor of the present invention has made various studies on the background described above, and as a result, it has been found that the propagation velocity information and the blood pressure value of the living body are obtained by using the heart rate as the information on the central side of the blood circulation. It has been found that, when the relationship is corrected, the reliability of the determination of the abnormal blood pressure of the living body can be further improved. The present invention has been made based on such findings.

That is, the gist of the present invention is as follows.
A blood pressure measuring means for measuring a blood pressure value of the living body using a cuff for changing a compression pressure on a part of the living body, and a preset blood pressure measurement value between the blood pressure measured value by the blood pressure measuring means and the pulse wave propagation velocity information of the living body. A blood pressure monitoring device of a type comprising: an estimated blood pressure value determining means for sequentially determining an estimated blood pressure value of the living body based on the pulse wave propagation information of the actual living body from the relationship, wherein (a) calculating the heart rate of the living body (B) a relation correction for correcting a preset relation between the measured blood pressure value and the pulse wave propagation velocity information of the living body based on the heart rate calculated by the heart rate calculation means. Means.

[0007]

In this way, the relation correcting means sets a predetermined relation between the measured blood pressure value and the pulse wave velocity information of the living body based on the heart rate calculated by the heart rate calculating means. Is corrected. Therefore, the accuracy of the estimated blood pressure value estimated from the relationship can be improved, and the reliability of blood pressure monitoring can be improved.

[0008]

Here, preferably, the relationship is a relationship (EB) between the pulse wave transit time DT and the estimated blood pressure value EBP.
P = αDT + β), and the relation correcting means corrects the relation by decreasing the absolute value of the coefficient α (negative value) of the pulse wave transit time DT in the relation as the heart rate HR increases. Things. Further, the relationship is a relationship (EBP) between the pulse wave velocity V _M and the estimated blood pressure value EBP.
= ΑV _M + β), and the relation correcting means increases the pulse wave velocity V within the relation as the heart rate HR increases.
_The relationship is corrected by increasing the coefficient α (positive value) of _M. In this way, for example, when the heart rate HR increases, the relationship is corrected in the direction in which the estimated blood pressure value increases, so that the accuracy of the estimated blood pressure value and the reliability of blood pressure monitoring are improved.

Preferably, (c) heartbeat cycle determining means for determining a heartbeat cycle of the living body, (d) peripheral pulse wave detecting means for detecting a pulse wave in a peripheral part of the living body, and (e) Pulse wave area calculating means for calculating the area of the peripheral pulse wave detected by the peripheral pulse wave detecting means; and (f) the estimated blood pressure value exceeds a predetermined criterion value, Blood pressure measurement activation means for activating the blood pressure measurement by the blood pressure measurement means based on at least one of the pulse wave areas exceeding a predetermined judgment reference value. According to this configuration, the estimated blood pressure value calculated by the estimated blood pressure value determination means exceeds a predetermined reference value,
In addition, the blood pressure measurement is started by the blood pressure measurement unit by the blood pressure measurement start unit based on at least one of the heartbeat cycle and the pulse wave area exceeding a predetermined reference value. Therefore, the criterion value can be made closer to the normal value as compared with the case where the blood pressure measurement by the blood pressure measurement unit is simply started based on the fact that the estimated blood pressure value is abnormal. With no delay, the abnormality of the blood pressure value can be reliably determined, and the reliability of blood pressure monitoring can be further improved.

Preferably, the means for detecting the pulse wave propagation information of the living body includes a part from a predetermined part of the electrocardiographic lead waveform to a predetermined part of the pressure pulse wave or the volume pulse wave detected on the peripheral side. A pulse wave propagation information calculating means for calculating the propagation time or the propagation speed from the time difference is provided. By doing so, the time difference becomes larger as compared with the case where the pressure pulse wave sensors are provided at two sites on the artery, and the measurement accuracy is improved.

Preferably, as the peripheral pulse wave detecting means for detecting the peripheral pulse wave, a light emitting element for irradiating the epidermis with light containing a wavelength reflected by hemoglobin in blood, and the hemoglobin thereof A photoplethysmographic sensor including a light receiving element for detecting scattered light scattered by the light from the epidermis is provided. In this manner, there is an advantage that a photoelectric pulse wave indicating a change in blood volume for each beat, that is, a volume pulse wave is easily detected.

Preferably, the pulse wave area calculating means calculates a normalized pulse wave obtained by normalizing the area of the photoplethysmogram by the period and amplitude of the pulse wave. In this way, there is an advantage that changes over time and individual differences are eliminated.

Preferably, an estimated blood pressure value sequentially calculated by the estimated blood pressure value determining means, a heartbeat cycle sequentially determined by the heartbeat cycle determining means, and a peripheral portion sequentially calculated by the pulse wave area calculating means. Of the pulse wave area along a common time axis that can be compared with each other. With this configuration, the basis of the activation operation by the blood pressure measurement activation unit can be confirmed by comparing the estimated blood pressure value, the cardiac cycle, and the peripheral pulse wave area displayed on the display with each other. Along with the period in which the blood pressure measurement is not performed by the blood pressure measurement unit,
The state of the circulatory dynamics of the living body can be easily monitored.

Preferably, the apparatus further comprises an electrocardiographic lead device for detecting an electrocardiographic lead waveform through an electrode attached to the epidermis of the living body, wherein the heartbeat cycle determining means includes a predetermined part of the cardiac lead waveform, for example, R It determines the time interval between waves.

[0015]

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

In FIG. 1, the blood pressure monitoring device 8 has a rubber bag in a cloth band bag, for example, the upper arm 12 of a patient.
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
Switches between three states: a pressure supply state in which the supply of pressure into the cuff 10 is permitted, a slow discharge state in which the cuff 10 is gradually discharged, and a rapid discharge state in which the cuff 10 is rapidly discharged. It is configured to be.

The pressure sensor 14 detects the pressure in the cuff 10 and outputs a pressure signal SP representing the pressure to the static pressure discriminating circuit 2.
2 and the pulse wave discrimination circuit 24. The static pressure discriminating circuit 22 has a low-pass filter, discriminates a cuff pressure signal SK representing a steady pressure included in the pressure signal SP, that is, a cuff pressure, and converts the cuff pressure signal SK into an A / D converter 26.
To the electronic control unit 28 via the Pulse wave discrimination circuit 2
Reference numeral 4 denotes a band pass filter, which discriminates a pulse wave signal SM ₁ which is a vibration component of the pressure signal SP in frequency, and converts the pulse wave signal SM ₁ via the A / D converter 30 into the electronic control unit 2.
8 The cuff pulse wave represented by the pulse wave signal SM ₁ is
These are pressure vibration waves 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 electrocardiograph 34 continuously detects an electrocardiogram, which is a so-called electrocardiogram, indicating an action potential of the myocardium through a plurality of electrodes 36 attached to a predetermined portion of a living body. A signal SM ₂ indicating an electrocardiographic wave is supplied to the electronic control unit 28. It should be noted that the electrocardiographic guiding device 34
Is for detecting the Q wave or the R wave of the electrocardiographic induction wave corresponding to the time when the blood in the heart starts to be pumped toward the aorta, and thus functions as the first pulse wave detection device. doing.

The pulse oximeter photoelectric pulse wave detecting probe 38 (hereinafter simply referred to as a probe) functions as a second pulse wave detecting device or a peripheral pulse wave detecting means for detecting a pulse wave transmitted to a peripheral artery including a capillary blood vessel. For example, it is attached to a living body skin such as a fingertip of a person to be measured, that is, a body surface 40, in close contact with a wearing band (not shown). The probe 38 is provided in a container-like housing 42 that opens in one direction and a portion located on the outer peripheral side of the bottom inner surface of the housing 42.
A plurality of first light-emitting elements 44 _a and second light-emitting elements 44 _b (hereinafter, simply referred to as light-emitting elements 44) formed of an ED or the like and a central part of the bottom inner surface of the housing 42 are provided. A light receiving element 46 composed of a phototransistor or the like; a transparent resin 48 integrally provided in the housing 42 to cover the light emitting element 44 and the light receiving element 46;
Between the light emitting element 44 and the light receiving element 46.
And a ring-shaped shielding member 50 for shielding the reflected light from the light-receiving element 46 toward the light-receiving element 46.

[0021] 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 800 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, an electric signal SM _R due to the red light through a sample hold circuit 56 and A / D converter 58 Then, an electric signal SM _IR by infrared light is sequentially supplied to an I / O port (not shown) of the electronic control device 28 via the sample hold circuit 60 and the A / D converter 62. When outputting the input electric signals SM _R , SM _IR to the A / D converters 58, 62, the sample hold circuits 56, 60 convert the A / D converters for the previously output electric signals SM _R , SM _IR . 58,
By the time the conversion operation at 62 is completed, the electric 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 switching the demultiplexer 54 outputs the C, sample and hold circuit 56 to the electric signal SM _R
Then, the electric signal SM _IR is distributed to the sample and hold circuit 60. The CPU 29 calculates the blood oxygen saturation of the living body based on the amplitude values of the electric 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 is a functional block diagram illustrating a main part of the control function of the electronic control unit 28 in the blood pressure monitoring device 8. 2, blood pressure measuring means 70, the target pressure value pressing pressure is in a predetermined cuff 10 wound around the upper arm, for example vivo by the cuff-pressure changing means 72 P _CM (e.g., pressure values of about 180 mmHg) until quick increasing After that, in a gradual step-down period in which the pressure is reduced at a speed of about 3 mmHg / sec, a well-known oscillometric method is used based on the change in the amplitude of the pulse wave represented by the pulse wave signal SM ₁ sequentially sampled. The systolic blood pressure BP _SYS , the average blood pressure BP _MEAN ,
And the diastolic blood pressure BP _DIA are determined.

The pulse wave propagation information calculating means 74 is shown in FIG.
Is sequentially detected by the electrocardiograph 34 as described above.
From a predetermined site, such as an R-wave, that occurs at each wave cycle,
The pulse is emitted for each period of the photoplethysmogram sequentially detected by the lobe 38.
Predetermined site, for example, rising point or lower peak
Time difference to point (pulse wave propagation time) DT_RPIs calculated sequentially
Time difference calculation means, and the time difference calculation means
Calculated time difference DT _RPNumber stored in advance based on
From equation 1, the propagation velocity of the pulse wave propagating in the artery of the subject
V_M(M / sec) is calculated sequentially. Note that in Equation 1,
L (m) is measured by the probe 38 from the left ventricle via the aorta.
The distance to the part to be mounted_{PE P}(Sec) is the heart
Precursor from R wave of photo-induced waveform to lower peak point of photoplethysmogram
It is out period. These distance L and pre-ejection period T_PEP
Is a constant, and a value experimentally obtained in advance is used.
You.

[0027]

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

The correspondence determining means 76 includes a blood pressure measuring means 7
Systolic blood pressure value BP measured by 0 _SYSAnd each blood
Pulse wave propagation time DT during pressure measurement period_RPOr pulse wave
Seeding speed V_M, For example, the pulse wave transit time within that period
DT_RPOr the propagation speed V_MEquation 2 based on the average value of
Alternatively, the pulse wave transit time DT expressed by Equation 3_RPOr propagation
Speed V_MAnd systolic blood pressure BP_SYSAnd the coefficient in the relational expression
α and β are determined in advance. Note that the above systolic blood pressure value BP
_SYSInstead of the average measured by the blood pressure measuring means 70
Blood pressure value BP_MEANOr diastolic blood pressure BP_DIAAnd blood pressure measurement period
Pulse wave propagation time DT within the interval_RPOr the propagation speed V_MWhen
May be determined. In short, monitor (estimate) blood
Set the pressure value EBP as the systolic blood pressure value or the average blood pressure value
Or the lowest blood pressure value.

[0029]

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

[0030]

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

The estimated blood pressure value determining means 78, from the relationship between the blood pressure value of the living and the pulse-wave propagation time DT _RP or the propagation velocity V _M of the living (Equation 2 and Equation 3), the pulse wave propagation information calculating means 74 successively determines the estimated blood pressure value EBP based on the actual pulse wave propagation time DT _RP or the propagation velocity V _M of the living body sequentially calculated, as shown in FIG. 4, which will be described later and the estimated blood pressure EBP A trend is displayed on the display 32 along with the heartbeat period RR and the pulse wave area VR so as to be comparable along a common time axis.

The heartbeat cycle determining means 82
The heartbeat period RR is determined by measuring the interval between predetermined portions of the electrocardiographic waveform obtained in Step 4, for example, the R-wave interval. Further, the pulse wave area calculation means 84 normalizes and calculates the area S of the photoelectric pulse wave obtained by the photoelectric pulse wave detection probe 38 based on the one cycle W and the amplitude L, and calculates the normalized pulse wave area VR. calculate. That is, as shown in FIG. 5, the photoplethysmogram is constituted by a series of points indicating the magnitude of the photoplethysmogram input at every sampling period of several millimeters or several tens of millimeters. After the area S of the photoelectric pulse wave is obtained by integrating (adding) the photoelectric pulse wave in W, the normalized pulse wave area VR is calculated by performing the calculation of S / (W × L). . The normalized pulse wave area VR is a dimensionless value indicating the area ratio in a rectangle surrounded by the one cycle W and the amplitude L, and
Also referred to as MAP.

The blood pressure measurement activating means 86 determines that the estimated blood pressure value EBP determined by the estimated blood pressure value determining means 78 has exceeded a predetermined reference value, and that the heartbeat period RR
And at least one of the pulse wave area VR exceeds a predetermined criterion value.
Activate blood pressure measurement by 0. That is, the blood pressure measurement activation means 86 sets the estimated blood pressure value EBP determined by the estimated blood pressure value determination means 78 to a predetermined reference value, for example, a predetermined value based on the previous blood pressure measurement by the blood pressure measurement means 70 using the cuff. Alternatively, the estimated blood pressure value abnormality judging means 8 for judging an abnormality based on a change of a predetermined ratio or more.
7. Heartbeat cycle R determined by heartbeat cycle determination means 82
R is a predetermined criterion value, for example, the blood pressure measuring means 7
The pulse wave area VR calculated by the heartbeat cycle abnormality determining means 88 and the pulse wave area calculating means 84 is determined in advance when the blood pressure has been changed by a predetermined value or a predetermined rate from the previous time when the blood pressure was measured by the previous cuff by 0. A pulse wave area abnormality judging means 89 for judging an abnormality based on a determined reference value, for example, a change of a predetermined value or a predetermined rate or more from the time when the blood pressure was previously measured by the blood pressure measuring means 70 as a reference. Judgment means 87
When the estimated blood pressure value EBP is determined to be abnormal and the heartbeat cycle abnormality determining means 88 determines that the heartbeat cycle RR is abnormal, or when the pulse wave area abnormality determining means 89 determines that the pulse wave area VR is abnormal. , The blood pressure measuring means 70
Activate blood pressure measurement by.

The heart rate calculating means 90 calculates the heart rate HR of the living body.
(1 / min) is converted to, for example, a predetermined relationship (HR = 60 / R
R) is calculated based on the heartbeat period RR (sec). The relationship correcting unit 92 corrects the relationship determined by the correspondence determining unit 76, for example, the relationship of Expression 2 or 3, based on the heart rate HR of the living body. For example, the above relationship is represented by the pulse wave transit time D
Relationship between T _RP and estimated blood pressure value EBP (EBP = αDT
_{In the case of RP} + β), the relation correcting means 92 determines that the larger the heart rate HR, the smaller the absolute value of the coefficient α (negative value) of the pulse wave transit time DT _RP in the relation, the greater the value of the equation. 2 is modified. When the absolute value of the coefficient α of the pulse wave transit time DT _RP decreases, as shown in FIG. 6, the slope of the line indicating the relationship of Equation 2 becomes gentler, and the estimated blood pressure value EBP for the same pulse wave transit time DT _RP increases. Therefore, for example, when the heart rate HR increases,
The relationship is corrected in the direction in which the estimated blood pressure value increases. Also,
If the above relationship is a relationship between the pulse wave velocity V _M and the estimated blood pressure value EBP (EBP = αV _M + β) as shown in Expression 3, the relationship correction means 92 sets the heart rate H
R is larger, it is intended to correct the relationship of Equation 3 by increasing the coefficient of the pulse wave propagation velocity V _M in the relationship alpha (positive value). The coefficient α of the pulse wave velocity V _M
When but increased, since the estimated blood pressure EBP increases for the same pulse-wave propagation velocity V _M becomes strong slope of the line showing the relationship between Equation 3 as shown in FIG. 7, for example, heart rate H
When R increases, the relationship is corrected in the direction in which the estimated blood pressure value increases.

FIGS. 8, 9 and 10 are flow charts for explaining the main control operation of the electronic control unit 28 of the blood pressure monitoring device 8. FIG. 8 is a blood pressure monitoring control routine showing a blood pressure monitoring control operation, FIG. 9 is a blood pressure measurement activation determination routine, and FIG. 10 is an independent process from FIG. 8 and FIG. This is a relation correction routine to be executed.

In FIG. 8, after executing an initial process for clearing flags, counters, and registers (not shown) in step SA1 (hereinafter, steps are omitted),
In SA2 corresponding to the pulse wave propagation information calculation means 74, the time difference from the R wave of the electrocardiographic waveform to the rising point of the photoelectric pulse wave sequentially detected by the probe 38, that is, the propagation time DT _RP is determined in the cuff pressure rising period, on the basis of the equation 1 on the propagation time TP pulse wave velocity V _M (m / sec
) Is calculated just before the cuff pressure rise.

Next, in SA3 and SA4 corresponding to the cuff pressure control means 72, the switching valve 16 is switched to the pressure supply state and the air pump 18 is driven, so that the cuff 10 is rapidly increased for blood pressure measurement. There together is started, the cuff pressure P _C is whether a preset target pressing pressure P _CM than about 180mmHg is determined.
If the determination in SA4 is negative, increasing the cuff pressure P _C by the SA2 below is repeatedly executed is continued.

However, the cuff pressure P_CThe above SA
If the determination in step 4 is affirmative, the blood pressure measurement means 70
In SA5, the blood pressure measurement algorithm is executed.
You. That is, the air pump 18 is stopped and the switching valve 1
6 is switched to the slow exhaust pressure state and the pressure in the cuff 10 is
Lower at a fixed speed of about 3 mmHg / sec.
As a result, the pulse wave signal obtained successively during this slow down process
SM₁ Based on the change in the amplitude of the pulse wave represented by
Oscillometric blood pressure determination algorithm
Tte systolic blood pressure BP_SYS, Mean blood pressure value BP_MEAN,and
Minimum blood pressure BP _DIAIs measured and the pulse wave interval
The pulse rate and the like are determined based on this. And that
The measured blood pressure value and pulse rate are displayed on the display 32.
And the switching valve 16 switches to the rapid exhaust pressure state.
As a result, the pressure in the cuff 10 is rapidly exhausted.

Next, at SA6 corresponding to the correspondence relationship determining means 76, the pulse wave propagation time DT _RP or the pulse wave velocity V _M obtained at SA2 and the blood pressure value BP _SYS by the cuff 10 measured at SA5. , BP _MEAN , or BP _DIA . That is,
In SA5, the blood pressure values BP _SYS , BP _MEAN , and BP
_{When the DIA} is measured, the blood pressure values BP _SYS , B
Based on one of P _MEAN or BP _DIA and the pulse wave transit time DT _RP or pulse wave velocity V _M , the pulse wave transit time DT _RP or pulse wave velocity V _M and the estimated blood pressure value EBP
(Equation 2 or 3) is determined.

When the pulse wave propagation information blood pressure correspondence is determined as described above, it is determined in SA7 whether the R wave of the electrocardiographic waveform and the photoelectric pulse wave have been input. This S
If the determination of A7 is denied, SA7 is repeatedly executed. If the determination is affirmed, in SA8 corresponding to the pulse wave propagation information calculation means 74, the R wave of the newly input electrocardiographic waveform and the photoelectric Pulse wave transit time DT for pulse wave
_RP and pulse wave velocity V _M are calculated in the same manner as SA2.

[0041] In SA9 corresponding to the estimated blood-pressure determining means 78, from the propagation velocity relationship between blood pressure determined in the above SA6, the pulse wave propagation time obtained in the above SA8 DT _RP or the pulse wave propagation velocity V _M The estimated blood pressure value EBP (systolic blood pressure value, average blood pressure value, or diastolic blood pressure value) is determined based on the estimated blood pressure value EBP.
The BP is output to the display 32 for trend display.

Next, in SA10 corresponding to the blood pressure measurement activation means 86, for example, a blood pressure measurement activation determination routine shown in FIG.
Starts the blood pressure measurement by the blood pressure measurement means 70 based on the fact that exceeds the predetermined reference value and that at least one of the heartbeat cycle RR and the pulse wave area VR exceeds the predetermined reference value. .

In FIG. 9, the heartbeat cycle determining means 82
In SA101 corresponding to, after the cardiac cycle RR is calculated from the electrocardiographic lead waveform obtained by the electrocardiographic lead device 34,
In SA102 corresponding to the heartbeat cycle abnormality determination means 88, it is determined whether or not the heartbeat cycle RR is abnormal, for example, by a predetermined value or a predetermined rate (for example, 5% up and down) based on the previous blood pressure measurement by the cuff. The determination is made based on the fact that the changed state continuously exceeds a predetermined number of beats, for example, 20 or more beats. If the determination of SA102 is denied, the process of SA104 and subsequent steps are directly executed. If the determination is affirmed, the RR flag for indicating the abnormality of the heartbeat period RR is turned on in SA103.

Next, in SA 104 corresponding to the pulse wave area calculating means 84, after a normalized pulse wave VR is calculated from the photoelectric pulse wave obtained by the photoelectric pulse wave detecting probe 38,
In SA105, it is determined whether the photoplethysmogram detected in the peripheral portion is normal. The SA 105 is for removing abnormalities in the shape of the photoplethysmogram, for example, those in which the slope of the base line is equal to or more than a predetermined value, or those in which the pulse wave shape is shifted halfway due to calibration. If the determination at SA105 is negative, SA110 and below are executed, but if affirmative, SA106 and below are executed.

In SA106 corresponding to the pulse wave area abnormality judging means 89, it is determined whether or not the normalized pulse wave VR calculated in SA104 is abnormal, for example, by a predetermined value based on the previous blood pressure measurement by the cuff. Alternatively, the determination is made based on the fact that the state changed by a predetermined ratio (for example, 3% up and down) continuously exceeds a predetermined number of beats, for example, 20 or more beats. If the determination of SA106 is denied, SA
Steps 108 and below are directly executed, but if affirmative, at SA107, the VR flag for indicating the abnormality of the pulse wave area VR is turned on.

Next, the estimated blood pressure value abnormality determining means 87
In SA108 corresponding to, whether the estimated blood pressure value EBP determined in SA9 is abnormal is, for example, changed by a predetermined value or a predetermined ratio (for example, up and down 30%) or more from the previous blood pressure measurement by the cuff. The determination is made based on the fact that the number of consecutive beats exceeds a predetermined number of beats, for example, 20 beats or more. If the determination at SA108 is denied, SA110 and subsequent steps are directly executed, but if affirmed, the estimated blood pressure EBP is determined at SA109.
The EBP flag for indicating the abnormality of is turned on.

In SA110, it is determined whether the EBP flag is turned on and the RR flag is turned on, or whether the EBP flag is turned on and the VR is turned on.
It is determined whether the flag is turned on. If the determination at SA110 is negative, SA11 is executed. In SA11, it is determined whether or not the elapsed time from the blood pressure measurement by the cuff 10 in SA5 has passed a preset cycle of about 15 to 20 minutes, that is, a calibration cycle. This SA1
If the determination of No. 1 is denied, the blood pressure monitoring routine of SA7 and below is repeatedly executed, the estimated blood pressure value EBP is continuously determined for each beat, and the determined estimated blood pressure value EBP is displayed on the display. At 32, a trend is displayed in chronological order. However, if the determination in SA11 is affirmed, the cuff calibration routine of SA2 and below is executed again to re-determine the correspondence.

However, if the determination at SA110 is affirmative, after SA12 of FIG. 8 is executed and an abnormal display of the estimated blood pressure value is displayed on the display 32, SA2 and below are set to re-determine the correspondence. Is executed again, whereby blood pressure measurement by the cuff is started.

In FIG. 10, the heart rate calculating means 90
In SB1, the heart rate HR of the living body is calculated based on, for example, the heartbeat period RR, and then SB2 to SB5 corresponding to the relationship correcting means 92 are executed. First, at SB2, whether to increase beyond the upper limit level value HR _UL the heart rate HR is set in advance is determined. Also,
If the determination in SB2 is negative, whether or not reduced below the minimum level value HR _LL the heart rate HR is set in advance is determined. The upper limit level value HR _UL and the lower limit level value HR _LL are determined by measuring the blood pressure of the living body with the cuff 10 by the previous blood pressure measuring means 70 and obtaining the blood pressure value and the pulse wave propagation information at that time. Heart rate HR when the relationship is determined by the correspondence determining means 76
It is preferably set to a value of, for example, about 20% above and below with reference to the average value of the 10 beats, and the estimated blood pressure EB
It is experimentally set in advance to a value that requires modification of the relationship of Expression 2 or Expression 3 in order to maintain the accuracy of P. When the blood pressure value BP of the living body changes, the pulse wave propagation information (D
T, V _M ), but there is a phenomenon in which the heart rate HR does.

When the determination at SB2 is affirmative, S
In B4, the correspondence is as shown in Equation 2 when a pulse wave is propagated.
DT between_RPBetween EBP and the estimated blood pressure value EBP (EBP = α
DT _RP+ Β), when the pulse wave propagation within the relationship
DT between_RPThe absolute value of the coefficient α (negative value) of
You. For example, change the coefficient α from -1.2 to -0.8
Can be The corresponding relationship is represented by the pulse wave propagation velocity V shown in Expression 3._M
Between EBP and the estimated blood pressure value EBP (EBP = αV_M+
β), the pulse wave velocity V within the relationship _Mof
Modified by increasing the coefficient α (positive value)
You. For example, the coefficient α is changed from 0.8 to 1.2
You.

If the determination at SB3 is affirmative,
Contrary to the above, the correspondence is expressed by the pulse wave propagation shown in Equation 2.
DT between_RPBetween EBP and the estimated blood pressure value EBP (EBP = α
DT _RP+ Β), when the pulse wave propagation within the relationship
DT between_RPThe absolute value of the coefficient α (negative value) of
You. For example, change the coefficient α from -0.8 to -1.2
Can be The corresponding relationship is represented by the pulse wave propagation velocity V shown in Expression 3._M
Between EBP and the estimated blood pressure value EBP (EBP = αV_M+
β), the pulse wave velocity V within the relationship_Mof
The coefficient α (positive value) is reduced. For example, if the coefficient α is
It is changed from 1.2 to 0.8.

As described above, according to the present embodiment, the estimated blood pressure value EBP and the biological data are calculated by the relationship correcting means 92 (SB2 to SB5) based on the heart rate HR calculated by the heart rate calculating means 90 (SB1). Pulse wave velocity information (D
T or V _M ) since the preset relationship (Equation 2 or 3) is modified so that the estimated blood pressure value EBP increases as the heart rate HR increases, and is estimated from the relationship. Since the accuracy of the estimated blood pressure value is increased, the reliability of blood pressure monitoring can be improved.

That is, the above relationship is equivalent to the pulse wave propagation time DT
And the relationship between the estimated blood pressure value EBP (EBP = αDT +
In the case of β), the relation correcting means 92 determines the heart rate
As HR increases, pulse wave transit time DT within that relationship
By reducing the absolute value of the coefficient α (negative value)
Modify the clerk. In addition, the above relationship indicates that the pulse wave velocity V_MWhen
Relationship between estimated blood pressure value EBP (EBP = αV_M+ Β)
, The relationship correcting means 92 determines that the heart rate HR
Becomes larger, the pulse wave propagation velocity V within the relation becomes larger. _MPerson in charge
Modify the relationship by increasing the number α (positive value)
Things. In short, the relation correcting means 92 determines the heart rate H
The direction in which the estimated blood pressure value EBP increases as R increases
The blood pressure monitoring accuracy and blood pressure monitoring
Reliability is improved.

FIG. 11 shows the trends of the blood pressure value BP, the estimated blood pressure value EBP, and the heart rate HR of the living body.
In t _a time after 11, although the divergence of the estimated blood pressure value EBP from blood pressure BP of a living body is observed, the heart rate H
Since R increases with the blood pressure value BP of the living body, for example, if the correspondence is corrected at time t _b , the estimated blood pressure EBP
Is determined to be a value slightly higher than the blood pressure value BP of the living body. The correction of the coefficient α by the relation correcting means 92 is set as described above. Therefore, the determination of abnormal blood pressure is on the safe side, and the reliability of blood pressure monitoring is further enhanced.

Further, according to the present embodiment, the estimated blood pressure value EBP determined by the estimated blood pressure value determining means 78 (SA9).
Exceeds a predetermined reference value, and the heartbeat cycle determining means 82 (SA101) and the pulse wave area calculating means 8
4 (SA104), based on the fact that at least one of the heartbeat period RR and the pulse wave area VR exceeds a predetermined judgment reference value, the blood pressure measurement activation means 86
(SA101 to SA110) The blood pressure measuring means 70
Blood pressure measurement is activated. Therefore, simply
Compared with the case where the blood pressure measurement is started by the blood pressure measurement unit based on the fact that the estimated blood pressure value is abnormal, the judgment reference value can be made closer to the normal value, and there is no delay even for a sudden blood pressure change. Thus, the abnormality of the blood pressure value can be reliably determined, and the reliability of blood pressure monitoring can be improved.

According to the present embodiment, the pulse wave area calculating means 84 (SA104) calculates the area S of the photoelectric pulse wave.
Is normalized by the pulse wave period W and the amplitude L to calculate a normalized pulse wave VR. In this way, there is an advantage that changes over time and individual differences are eliminated.

Further, according to the present embodiment, the estimated blood pressure value E sequentially calculated by the estimated blood pressure value determining means 78 (SA9).
The BP, the heartbeat cycle RR sequentially determined by the heartbeat cycle determination means 82, and the peripheral pulse wave area VR sequentially calculated by the pulse wave area calculation means 84 are trend-displayed along a common time axis so as to be comparable. Since the display 32 is provided, the estimated blood pressure value EBP, the cardiac cycle RR, and the peripheral pulse wave area VR displayed on the display 32 are compared with each other, so that the activation operation by the blood pressure measurement activation unit 86 is performed. The reason can be confirmed, and the state of the circulatory dynamics of the living body can be easily monitored during the period in which the blood pressure measurement by the blood pressure measurement means 70 is not performed.

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, the blood pressure measuring means 7 of the above embodiment
0 is configured to measure the blood pressure by the so-called oscillometric method, but measures the blood pressure by the so-called K sound method that determines the cuff pressure at the time of occurrence and disappearance of the Korotkoff sound as the systolic blood pressure value and the diastolic blood pressure value. It can be anything.

In the above-described embodiment, the photoelectric pulse wave detecting probe 38 is used as the peripheral pulse wave detecting means. However, for example, an impedance pulse wave detecting device for detecting a change in impedance through an electrode attached to a finger. Alternatively, a pressure pulse wave detecting device that is pressed by the radial artery to detect the internal pressure may be used. In short, any pulse wave that reflects the circulatory dynamics of the peripheral part of the living body may be used.

In the above-described embodiment, the electrocardiograph 3
4 and detection of the predetermined part of the electrocardiographic waveform and photoelectric pulse wave detected by
Of the photoplethysmogram detected by the probe 38
Pulse wave propagation time DT based on the time difference between_RPOr pulse wave
Seeding speed V_MWas required, but the carotid or brachial artery
1st pulse wave detection device attached to the wrist or finger
Pulse wave propagation time DT between the second pulse wave detection device_RP
Or pulse wave velocity V _MMay be required.

Further, in the above-described embodiment, the photoelectric pulse wave detecting probe 38 for the oximeter functions as the second pulse wave detecting device. However, the cuff 10 detects a cuff pulse wave from the cuff 10 holding a predetermined pressure. A pulse wave sensor, a pressure pulse wave sensor for detecting a pulse wave by pressing a radial artery, an impedance pulse wave sensor for detecting the impedance of an arm or a fingertip through an electrode, and a photoelectric pulse wave attached to a fingertip for detecting a photoelectric pulse wave Other types, such as a type of transmissive photoplethysmographic sensor, may also be used.

[0063] Further, in the embodiment described above, the pulse wave velocity V _M had been calculated on the basis of the time difference to the rising point of the photoelectric pulse wave from the R-wave, the electrocardiographic waveform from the Q wave 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.

In the above embodiment, the heartbeat period R
Since there is a one-to-one correspondence (HR = 60 / RR) between R (sec) and the heart rate HR (1 / min), which of the heartbeat cycle RR and the heart rate HR per unit time is used. Is also good.

In the above-described embodiment, the blood pressure measurement starting means 86 may not be provided. This is because the blood pressure can be monitored only by displaying the estimated blood pressure value EBP on the display 32 as a trend.

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 an estimated blood pressure value E obtained in the embodiment of FIG. 1;
FIG. 9 is a diagram showing an example in which a BP, a heartbeat period RR, and a pulse wave area VR are trend-displayed on a display.

FIG. 5 is a diagram illustrating a method of normalizing a pulse wave area VR in the embodiment of FIG.

FIG. 6 is a diagram showing a change in a coefficient of the pulse wave transit time DT in a relationship between the estimated blood pressure value EBP and the pulse wave transit time DT.

[7] in relation to the estimated blood pressure EBP and the pulse wave propagation velocity V _M, is a graph showing changes in coefficients of the pulse wave velocity V _M.

FIG. 8 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.

9 is a diagram for explaining in detail the operation of a blood pressure measurement start determination routine in SA10 of FIG. 6;

FIG. 10 is a flowchart illustrating a main part of a control operation of the electronic control unit in the embodiment of FIG. 1, and is a diagram illustrating a relation correction routine.

FIG. 11 is a time chart for explaining a control operation of the electronic control unit 28 in the embodiment of FIG.

[Explanation of symbols]

 10: Cuff 70: Blood pressure measuring means 76: Correspondence determining means 78: Estimated blood pressure value determining means 90: Heart rate calculating means 92: Relationship correcting means

Claims (1)

[Claims] 1. A blood pressure measuring means for measuring a blood pressure value of a living body using a cuff for changing a compression pressure on a part of the living body,
An estimated blood pressure value for sequentially determining an estimated blood pressure value of the living body based on the actual living body pulse wave propagation information from a preset relationship between the blood pressure measurement value by the blood pressure measuring means and the pulse wave propagation speed information of the living body. A blood pressure monitoring device of a type comprising a determination unit, a heart rate calculation unit that sequentially calculates a heart rate of the living body, and a heart rate calculated by the heart rate calculation unit.
A blood pressure monitoring device, comprising: a relationship correction unit configured to correct a preset relationship between the blood pressure measurement value and the pulse wave propagation velocity information of the living body.