JP3310761B2 - Blood pressure monitoring device - Google Patents

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 value of a living body without imposing a great burden.

[0002]

2. Description of the Related Art When continuously monitoring the blood pressure value of a living body, an automatic blood pressure measuring apparatus having a cuff wound around a part of the living body is used, and the blood pressure measurement by the automatic blood pressure measuring apparatus is performed at a predetermined cycle. In many cases, the blood pressure value is measured repeatedly. However, in such a case, if the measurement interval is shortened in order to increase the accuracy of blood pressure monitoring, the frequency of pressing the cuff against the living body increases, so that there is a disadvantage that a large burden is imposed on the living body.

On the other hand, a cuff attached to a part of a living body is pressurized to a predetermined value, a pulse wave which is a pressure oscillation generated in the cuff is detected, and a blood pressure value is determined based on the magnitude of the pulse wave. A device that monitors blood pressure by estimating it has been proposed. For example, those described in JP-A-61-103432 and JP-A-60-241422 are those.

[0004]

However, in the above conventional blood pressure monitoring device, if the pressure of the cuff is set as low as possible in order to reduce the burden on the living body, the pulse wave amplitude corresponding to the change in the blood pressure value is set. In some cases, the change hardly appeared and sufficient blood pressure monitoring accuracy could not be obtained. That is, the pulse wave amplitude obtained from the cuff changes with the pressure of the cuff at a predetermined normal blood pressure value, for example, as shown by the envelope of the pulse wave amplitude shown by the solid line in FIG. 8 has the property of changing like the envelope of the pulse wave amplitude indicated by the broken line,
When detecting a pulse wave amplitude in the pressure of the cuff is set relatively low, as shown in P _K in FIG. 8, since a small change in amplitude with respect to a change in blood pressure at such a low set pressure P _K In the case of monitoring blood pressure, sufficient accuracy could not be obtained.

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a blood pressure monitoring device capable of obtaining high blood pressure monitoring accuracy without imposing a burden on a living body.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the gist of the present invention is to monitor a blood pressure value of a living body by changing a compression pressure of a cuff wound around a part of the living body. A blood pressure monitoring device, comprising: (a) a pulse wave detecting means for detecting a pulse wave generated in the cuff when the cuff is compressed; and (b) the compression pressure of the cuff, after a predetermined rest period, Compression pressure control means for repeatedly changing to a predetermined pressure value lower than the average blood pressure value of the living body; and (c) determining a rate of change of the magnitude of the pulse wave with respect to a change in compression pressure of the cuff by the compression pressure control means. A change rate determining means, and (d) first abnormality determining means for determining an abnormal blood pressure value of the living body based on the change rate determined by the change rate determining means.

[0007]

With this configuration, the rate of change of the magnitude of the pulse wave with respect to the change in the compression pressure of the cuff by the compression pressure control means is determined by the change rate determination means, and the change rate determination means determines the change rate by the first abnormality determination means. An abnormal blood pressure value of the living body is determined based on the rate of change determined by the means.

[0008]

Therefore, according to the blood pressure monitoring apparatus of the present invention, the rate of change on the low pressure side of the envelope representing the change in the amplitude of the pulse wave due to the change in the pressure of the cuff changes in response to the change in the blood pressure value. Since blood pressure monitoring is performed utilizing this fact, high monitoring accuracy can be obtained. Further, since the above-mentioned rate of change can be obtained by changing the pressure of the cuff in a low pressure range from the atmospheric pressure to a predetermined pressure value, no burden is imposed on the living body.

Preferably, when the first abnormality determining means determines that the blood pressure of the living body is abnormal, the blood pressure value of the living body is automatically measured according to a predetermined series of measurement operations. Blood pressure measurement means is included. In this way, since the blood pressure value at the time of abnormal blood pressure is measured by the blood pressure measurement means, there is an advantage that an accurate blood pressure value can be immediately obtained and an accurate treatment can be performed.

Preferably, the first abnormality determining means determines whether the magnitude of the pulse wave is lower than a predetermined criterion value, and determines whether the magnitude of the pulse wave is lower than the predetermined criterion value. If it is lower than the value, it is determined that the blood pressure value of the living body is abnormally low. In the shock state of the living body, the envelope representing the change in the amplitude of the pulse wave due to the change in the pressure of the cuff becomes flat, so that it is easily based on the rate of change in the magnitude of the pulse wave with respect to the change in the compression pressure of the cuff. Although it is not determined, there is an advantage that the shock state of the living body can be easily determined.

Preferably, the compression pressure control means changes the compression pressure of the cuff to a predetermined constant pressure value, and thereafter maintains the constant pressure value for a predetermined holding period. And a second abnormality determining means for determining an abnormal blood pressure value of the living body based on the magnitude of the pulse wave detected during the predetermined holding period. As described above, the first blood pressure abnormality of the living body is determined based on the change rate of the magnitude of the pulse wave with respect to the change in the compression pressure of the cuff.
Since the abnormality determining means and the second abnormality determining means for determining an abnormal blood pressure value of the living body based on the magnitude of the pulse wave are provided, there is an advantage that the reliability of the blood pressure monitoring is improved.

Preferably, the compression pressure control means raises the compression pressure of the cuff to a predetermined first holding pressure and holds the same, and then sets the compression pressure to a value higher than the first holding pressure. The pressure is raised to the second holding pressure and held.
The change rate determining means is configured to determine a change rate of the magnitude of the pulse wave detected during the holding period of the first holding pressure and the holding period of the second holding pressure. In this way, the rate of change of the envelope low pressure side rising portion is calculated based on the constant first and second holding pressures, so that the rate of change is accurately determined, and the blood pressure monitoring accuracy is advantageously increased. . In this case, the rate-of-change determining means determines the rate of change based on the amplitude of the pulse wave when at least two similar pulse waves are input during the holding period of the first holding pressure and the holding period of the second holding pressure. It is configured to calculate.
In this case, since noise is removed from the pulse wave, there is an advantage that the accuracy of blood pressure monitoring is further improved.

Preferably, the second abnormality determining means is configured to determine an abnormal blood pressure value of the living body based on the magnitude of the pulse wave detected during the holding period of the second holding pressure. You. In this case, there is an advantage that the cuff pressure holding period for collecting a pulse wave serving as a basis for the abnormality determination by the second abnormality determination unit does not need to be provided independently.

Preferably, when at least one of the first abnormality determining means and the second abnormality determining means determines that the blood pressure value of the living body is abnormal, the blood pressure measuring means determines a predetermined series of times. Automatically measures the blood pressure value of the living body in accordance with the measuring operation. With this configuration, when at least one of the first abnormality determination unit and the second abnormality determination unit determines that the blood pressure value is abnormal, the blood pressure value is measured by the blood pressure measurement unit, so that the reliability of blood pressure monitoring is further improved. There are benefits that can be enhanced.

[0015] Preferably, the compression pressure control means changes the compression pressure of the cuff to a predetermined constant pressure value, and the criterion value in the first abnormality determination means is set to a desired value. A criterion value setting means for setting
Pressure value changing means for changing a constant pressure value changed by the compression pressure control means according to the judgment reference value set by the judgment reference value setting means is further included. In this way, there is an advantage that the cuff pressure on the living body can be reduced as much as possible.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a blood pressure monitoring apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings.

In FIG. 1, a cuff 10 wound around an upper arm of a living body is an inflatable bag 10a made of an elastic film such as a rubber sheet or a vinyl sheet. It is constituted by being accommodated in. The inflatable bag 10a of the cuff 10
Is a pressure sensor 12, an air pump 14, a pressure control valve 16
And an air pipe 18.

The pressure sensor 12 includes, for example, a semiconductor pressure detecting element, detects the pressure in the cuff 10, and outputs a pressure signal SP representing the pressure to the low-pass filter 20, the first band-pass filter 22, It is supplied to a two-bandpass filter 23. Low pass filter 20 is for taking out the pressure (static pressure) P _C of the cuff 10 to discriminate the DC component included in the pressure signal SP, and outputs it to the A / D converter 24 as a cuff pressure signal SK. The first band-pass filter 22 includes, for example, 1
A pulse wave component is extracted by discriminating a frequency component of 10 Hz to 10 Hz and output to the A / D converter 24 as a pulse wave signal SM1. In the cuff 10 wound around the upper arm or the like of the living body, a pressure fluctuation synchronized with the heartbeat is generated based on the pulsation of the artery. Then, the second band-pass filter 23 extracts a pulse wave component by discriminating a frequency component of 0.5 to 20 Hz included in the pressure signal SP, and extracts the A / D as a pulse wave signal SM2.
Output to the converter 24. First bandpass filter 22
The cuff 10 is synchronized with the heartbeat during the slowly changing pressure (2 to 3 mm / Hg) of the pressure of the cuff 10 for measuring the blood pressure.
While the second bandpass filter 23 has a narrow frequency characteristic for extracting the pressure vibration, that is, the pulse wave amplitude generated at the time, without the influence of noise such as motion artifact noise. The cuff 10 has a relatively wide frequency characteristic for accurately extracting a pulse wave having the same shape as the pressure pulse wave generated in the artery while holding the pressure of the cuff 10 for sampling. . The A / D converter 24 includes a multiplexer for time-dividing the three types of input signals, and has a function of performing A / D conversion on the three types of input signals in parallel. The first bandpass filter 2
The second and second bandpass filters 23 correspond to a pulse wave detection unit 50 described later.

The arithmetic and control unit 26 includes a CPU 28 and a RAM.
30, a so-called microcomputer including a ROM 32, an output interface 34, and a display interface 36. The CPU 28 stores a signal input from the A / D converter 24 in the ROM 32 in advance while using the temporary storage function of the RAM 30. Process according to the program
Drive control of the air pump 14 and the pressure control valve 16 is performed via the output interface 34, and drive control of the display 38 is performed via the display interface 36.
The display 38 is provided with an image display board capable of displaying numerical values and waveforms by a large number of pixels, and a printing machine capable of displaying numerical values and waveforms on paper as required by ink. In this embodiment, the display 38
Corresponds to the display means 66 described later.

The mode changeover switch 40 is operated to switch between the single measurement mode and the continuous monitoring mode, and selectively supplies a signal instructing the single measurement mode or the continuous monitoring mode to the CPU 28. The start / stop switch 42 supplies a signal to the CPU 28 for alternately instructing start and stop for each pressing operation.

FIG. 2 is a functional block diagram for explaining a main control function of the arithmetic and control unit 26. As shown in FIG. The blood pressure monitoring device in the figure includes a pulse wave detection unit 50 that detects a pulse wave that is a pressure signal generated in the cuff 10 in synchronization with a heartbeat when the cuff 10 wound around a part of the living body is compressed, Cuff 1
A blood pressure measuring means 52 for measuring a blood pressure value of the living body based on a change in the amplitude Am of a series of pulse waves obtained when the compression pressure of 0 is changed. The compression pressure control means 54 repeatedly changes the compression pressure of the cuff 10 to a predetermined pressure value lower than the average blood pressure value of the living body in a non-measurement period in which the blood pressure measurement means 52 does not perform the blood pressure measurement after a predetermined pause period. Let it. The rate of change determination means 56 determines the rate of change θ (ΔAm /) of the magnitude (amplitude) of the pulse wave with respect to the change in the compression pressure of the cuff by the compression pressure control means 54.
ΔP _C ) is determined. The first abnormality determining means 58 determines an abnormal blood pressure value of the living body based on the change rate θ determined by the change rate determining means 56.

When the blood pressure value is normal, an envelope is formed with the rising angle of the angle α on the low pressure side as shown by the solid line in FIG. 8, but when the blood pressure value decreases, the dashed line in FIG. As shown, since the whole value of the envelope is low and the peak moves to the low pressure side, as shown by the rising angle β of the one-dot chain line envelope, the blood pressure value decreases and the The rising angle is larger than the angle α at the time of normal blood pressure. By utilizing such properties, the first abnormality determination unit 58, a blood pressure value of the living body when the rate of change of the magnitude of the pulse wave (amplitude) theta is larger than a predetermined criterion value theta _O Is determined to be a blood pressure value abnormality in which the blood pressure decreases. However, in the shock state of the living body, the rising angle becomes small as shown by the two-dot chain line in FIG. 8, but the pulse wave amplitude value also becomes small. It is determined whether or not the value is lower than the value Amo, and if the magnitude of the pulse wave is lower than the determination reference value Amo, it is determined that the blood pressure value of the living body is abnormally low. The blood pressure measuring means 52 automatically measures the blood pressure value of the living body according to a predetermined series of measurement operations when the first abnormality determining means 58 determines that the blood pressure value of the living body is abnormal.

The compression pressure control means 54 increases the compression pressure of the cuff 10 from the atmospheric pressure to a predetermined constant pressure in order to detect pulse waves of different magnitudes for calculating the rate of change θ of the pulse wave amplitude. changing the value, even then maintained for a predetermined hold period T _3M to the constant pressure value P _CH for taking pulse wave for blood pressure monitor according to another method. The second abnormality determining means 60 determines an abnormal blood pressure value of the living body based on the magnitude of the pulse wave detected during the holding period _T3M from a predetermined relationship. The blood pressure measuring means 5
2 immediately executes the blood pressure measurement when the blood pressure value abnormality is determined by the second abnormality determination means 60. That is, when at least one of the first abnormality determination unit 58 and the second abnormality determination unit 60 determines that the blood pressure value of the living body is abnormal, the blood pressure measurement unit 52 immediately measures the blood pressure value of the living body.

Further, a criterion value setting means 62 for setting the criterion value in the first abnormality deciding means 58 or the second abnormality deciding means 60 to a desired value, and a judgment set by the criterion value setting means 62 Pressure value changing means 64 for changing a constant pressure value _PCH changed by the compression pressure control means 54 according to the reference value is further provided. When an abnormality is determined by the first abnormality determining means 58 or the second abnormality determining means 60,
The contents of the abnormality are displayed on the display means 66.

FIG. 3 and FIG.
6 is a flowchart for explaining the control operation of FIG. In step S <b> 1 in the figure, it is determined whether or not the activation of the blood pressure monitoring device has been operated based on a signal from the activation / stop switch 42. If the determination in step S1 is denied, the process is put on standby. If the determination is affirmed, the cuff 10 is quickly pressurized by the air pump 14 and the pressure control valve 16 in step S2.

[0026] In step S3, whether the cuff pressure P _C reaches a preset target pressure P _CM example 180mmHg is determined. If the determination in step S3 is denied, step S2 and subsequent steps are repeatedly executed. If the determination is affirmed, the air pump 14 is stopped and the opening of the pressure control valve 16 is controlled in step S4. As a result, the cuff 10 is slowly exhausted, and the cuff pressure is gradually reduced at a speed suitable for blood pressure measurement, for example, 2 to 3 mmHg / sec. Then, in step S5,
Whether or not one pulse wave has been input is determined based on pulse wave signal SM1. If the determination in step S5 is negative, step S4 and subsequent steps are repeatedly executed.

However, if the determination in step S5 is affirmative, a blood pressure value determination routine based on an oscillometric blood pressure value determination algorithm is executed in step S6, and the blood pressure value determination is completed in step S7. Is determined. In the slow down process of the cuff 10 during the blood pressure measurement period, the pulse wave amplitude based on the pulse wave signal SM1 has a property of gradually increasing at first at first and then decreasing gradually as shown in FIG. In the determination algorithm, for example, the cuff pressure value when the amplitude of the pulse wave sharply decreases is the systolic blood pressure value P _sys , the cuff pressure value when the amplitude of the pulse wave is maximum is the average blood pressure value P _mean , The cuff pressure value when the amplitude increases sharply becomes the minimum blood pressure value P
Each is determined as _dia .

If the determination in step S7 is negative, steps S4 and subsequent steps are repeatedly executed. If the determination is affirmative, the blood pressure values P _{sy s} , P _mean , and P _dia are stored in the RAM 30 in step S8. And the numerical value is displayed on the display 38, and the pressure control valve 16 is opened in step S9, the cuff 10 is rapidly evacuated, and the compression by the cuff 10 is eliminated. In the present embodiment, the steps S2 to S9 correspond to the blood pressure measurement unit 52 that automatically executes the blood pressure measurement according to a series of procedures.

In step S10, the relational expression for monitoring used in step S24 described below is
The blood pressure values P _sys and P _dia (or P _mean ) measured in step S6 and the pressure of the cuff 10 are determined based on the actual pulse wave amplitude value when the blood pressure value is determined. This relational expression is, for example, shown in FIG. 5, and shows the relation between the blood pressure value and the pulse wave amplitude value in a specific living body.

In the following step S11, it is determined whether or not the mode is the continuous monitoring mode based on a signal from the mode changeover switch 40. If the determination in step S11 is negative, the measurement mode is the one-time measurement mode, so that this routine is terminated, and steps S1 and subsequent steps are executed again.
However, when the determination in step S11 is affirmative, that is, when the continuous monitoring mode is set, the blood pressure monitoring routine from step S12 is repeatedly executed at a predetermined cycle of about 1 to 3 minutes.

In steps S12 and S13, the second
Timer counter T ₂ and first timer counter T ₁
Are cleared, and at step S1
After “1” is added to the contents of the first timer counter T ₁ and the second timer counter T ₂ in step 4, respectively, in step S15, the first timer counter T ₁ is added.
It is determined whether or not the content of has reached a predetermined reference value T _1M . The criterion value T _1M is previously set to the period, for example, about 1 to 3 minutes the pressure of the cuff 10 is raised to a predetermined holding pressure P _CH for blood pressure monitoring.

Initially, the determination in step S15 is denied, so that step S14 and subsequent steps are repeatedly executed. However, if the determination in step S15 is affirmed while the step is repeatedly executed, the pressure of the cuff 10 is gradually increased by the air pump 14 and the pressure control valve 16 in step S16. The slow pressure rising speed is set so that at least three or more pulse waves are generated until the pressure of the cuff 10 reaches a holding pressure _PCH described later. For example, a value of about 3 mmHg / sec is set. Adopted. Next, in step S17, every time a pulse wave is generated, the amplitude Am of the pulse wave is stored, and at least 3
An approximation line passing through the amplitudes Am of the two pulse waves is formed as shown on the low-pressure side of the envelope enclosing the pulse wave amplitude in FIG. 7, and from the approximation lines, a predetermined constant cuff pressure P _C-1 and a predetermined cuff pressure P _C-1. P
Based on the _C-2, the change rate of the pulse wave amplitude Am for the cuff pressure _{P C θ (ΔAm / ΔP C} ) is calculated from Equation 1. In Equation 1, Am ₁ and Am ₂ are the amplitude values of two consecutive pulse waves, and PC _-1 and PC _-2 are the amplitude values Am ₁
And Am ₂ are the pressure values of the cuff 10 when pulse waves are generated. In the present embodiment, step S17 corresponds to the change rate determining means 56.

[0033]

Equation ₁ θ = (Am ₂ −Am ₁ ) / (P _C−2 − PC _-1 )

Next, in step S18, it is determined whether or not the pulse wave amplitude change rate θ is larger than a predetermined reference value θ _O. The criterion value θ _O is a pulse wave envelope (for example, 1 in FIG. 8) corresponding to when the living body has a considerably low blood pressure value, for example, when the systolic blood pressure value and the diastolic blood pressure value are about 90 mmHg and 50 mmHg. It is set to the rate of change of the rising angle β on the low pressure side of the envelope shown by the dashed line). If the determination in step S18 is affirmative, step S19 is executed to display the display 38.
After the blood pressure decrease abnormality is displayed in step 2, steps S2 and subsequent steps corresponding to the blood pressure measurement means 52 are executed, and the blood pressure value when the blood pressure decrease abnormality is determined is immediately measured.

However, if the determination in step S18 is negative, in step S20, the pulse wave amplitude A
It is determined whether m is greater than a predetermined reference value Amo. The criterion value Amo is set to the amplitude of the pulse wave on the low pressure side of the envelope of the pulse wave (for example, the envelope indicated by the two-dot chain line in FIG. 8) corresponding to the time when the living body is in the shock state. If the determination in step S20 is denied, step S19 is executed to display the display 38.
After the blood pressure decrease abnormality indicating the shock state is displayed in step S2, steps S2 and subsequent steps corresponding to the blood pressure measuring means 52 are executed, and the blood pressure value when the shock state is determined is immediately measured. In the present embodiment, the step S18
And the step S20 corresponds to the first abnormality determining means 58.
It corresponds to.

[0036] In step S21, whether the host vehicle has reached the holding pressure P _CH cuff pressure P _C is set in advance is determined. The holding pressure P _CH is set to a pressure sufficiently lower than the average blood pressure value P _{mean and} a constant pressure at which a change in the pulse wave amplitude can be sufficiently recognized, for example, a pressure of about 20 to 30 mmHg. If the determination in step S21 is denied, the steps S16 and subsequent steps are executed again. If the determination is affirmative, in step S22, the slow pressure increase of the cuff 10 is stopped and the cuff 10 It is temporarily _{stored in the CH} for a predetermined holding period T _3M of about 2 seconds. Continued In step S23 the cuff 10 is read pulse wave amplitude Amh when held by the holding pressure P _CH, based on the relationship shown in which has been for example 5 prepared in the step S10 in step S24 to the pulse wave amplitude Amh And systolic blood pressure value P
_{The sysE} and the diastolic blood pressure value P _diaE are estimated.

In step S25, the estimated _systolic blood pressure value P _sysE is set to a predetermined reference value P
It is determined whether or not the value is _smaller than _sysEO and whether or not the diastolic blood pressure value P _diaE is _smaller than a predetermined reference value P _diaEO . These criterion values P _sysEO and P _diaEO are values for monitoring abnormal decrease in blood pressure of the living body, and for example, 90 mmHg and 50 mmHg are adopted. If at least one of the determinations in step S25 is affirmed, after step S26 is executed, a blood pressure decrease abnormality is displayed on the display 38, and steps S2 and subsequent steps corresponding to the blood pressure measuring means 52 are executed. Then, the blood pressure value when the blood pressure decrease abnormality is determined is immediately measured.

[0038] However, if the determination in step S25 is negative, after the cuff 10 whose pressure has been released is exhausted in step S27, the contents of the second timer counter T ₂ is set in advance in step S28 It is determined whether or not the determined reference value T _2M has been reached. This determination reference value T _2M is a time interval for periodically executing the blood pressure measurement routine of step S2 and _subsequent steps, and is appropriately set to a value of, for example, about 10 to 30 minutes. Initially, the determination in step S28 is denied, so that step S13 and subsequent steps are repeatedly executed. However, while such steps are repeatedly executed, the above-described step S
If the determination at 28 is affirmative, the steps from S2 onward are executed again.

Therefore, by repeatedly executing the above steps, the pressure of the cuff 10 is changed as shown in FIG. That is, in the blood pressure monitoring period in which the period of the blood pressure measurement performed in connection with the activation operation is completed, that is, in the non-blood pressure measurement period, the pressure of the cuff 10 is set to a predetermined T.
At a _1M period it is periodically allowed to Josoku boosted up to a certain holding pressure P _CH, its slow speed with hypotension abnormality is determined on the basis of the slow-speed pulse wave amplitude change rate detected by the boost process θ Based on the pulse wave amplitude Am detected during the pressure increase process, it is determined that the blood pressure is abnormally low in the shock state of the living body. Further, the blood pressure values P _sysE and P _diaE are estimated based on the pulse wave amplitude Amh detected at the constant holding pressure P _CH , and a blood pressure decrease abnormality is determined based on the estimated blood pressure values P _sysE and P _diaE. It is done.

As described above, according to the present embodiment, the compression pressure control means 54 increases the pressure of the cuff 10 for a predetermined rest period T _1M.
When the pressure is repeatedly increased slowly from the atmospheric pressure to a predetermined pressure value P _CH lower than the average blood pressure value P _{mean of the} living body, the rate of change θ of the magnitude of the pulse wave with respect to the change in the compression pressure of the cuff 10 changes. The blood pressure value abnormality of the living body is determined by the rate determining means 56 based on the change rate θ by the first abnormality determining means 58. As described above, according to the blood pressure monitoring device of the present embodiment, the pulse wave amplitude Am accompanying the pressure change of the cuff 10 is obtained.
Blood pressure monitoring is performed using the fact that the rate of change θ on the low pressure side of the envelope representing the change in the pressure changes in response to a change in the blood pressure value, so that high monitoring accuracy can be obtained. Also, cuff 10
By changing the pressure in the low pressure range from the atmospheric pressure to the above-mentioned pressure value _PCH , the above-mentioned rate of change θ can be obtained, so that no burden is imposed on the living body.

In this embodiment, when the first abnormality determining means 58 determines that the blood pressure of the living body is abnormal,
Since the blood pressure value of the living body is automatically measured according to a series of predetermined measurement operations by the blood pressure measurement means 52,
There is an advantage that an accurate blood pressure value at the time of abnormal blood pressure can be immediately obtained by the blood pressure measuring means 52 and an accurate treatment can be performed.

In the shock state of the living body, since the envelope representing the change in the amplitude of the pulse wave accompanying the change in the pressure of the cuff 10 becomes flat, the rate of change θ of the magnitude of the pulse wave with respect to the change in the compression pressure of the cuff is However, in this embodiment, the first abnormality determining means 58 also determines whether the pulse wave amplitude Am is lower than a predetermined criterion value Amo, and the pulse wave amplitude Am is determined based on the criterion. When the value is lower than the value Amo, it is determined that the blood pressure value of the living body is abnormally low.

In this embodiment, the compression pressure control means 5
Numeral 4 changes the compression pressure of the cuff 10 to a predetermined constant pressure value P _CH , and then maintains the pressure value P _CH for a predetermined holding period T _3M , and the predetermined holding period T _3M.
Is further provided with the second abnormality determination means 60 for determining an abnormality in the blood pressure value of the living body based on the magnitude Amh of the pulse wave detected in the above, there is an advantage that the reliability of the blood pressure monitoring is improved.

In this embodiment, the blood pressure measuring means 5
2 is a first abnormality determination unit 58 and a second abnormality determination unit 6
When the blood pressure value of the living body is determined to be abnormal by at least one of 0, the blood pressure value of the living body is automatically measured according to a predetermined series of measurement operations, so that the reliability of blood pressure monitoring is further improved. There is.

Next, another control operation example of the arithmetic and control unit 26 will be described. In the following description, the same parts as those in the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 9 shows another example of the routine for determining the pulse wave amplitude change rate θ in step S17 of FIG. 4 corresponding to the amplitude change rate determining means 56. Step S in FIG.
In 17-1, the pressure of the cuff 10 is held at the first holding pressure P _CH1 set in advance. The first holding pressure P _CH1 is the rate of change θ of the envelope indicating the magnitude of the pulse wave in FIG.
Is the pressure at which a pulse wave can be collected to detect
It is set to about 5 to 20 mmHg. Subsequent step S17
At -2, it is determined whether two consecutively input pulse waves for reading a pulse wave containing no noise have the same magnitude. In step S17-2 and step S17-5 described below, since the pressure of the cuff 10 is constant, a more accurate pulse wave filtered by the second band-pass filter 23 is used. This step S17-
If the determination of step 2 is denied, step S17-1 is performed again.
There is repeatedly executed, if a positive been amplitude values of the two pulse wave in step S17-3 is stored as a first pulse wave amplitude Am _1.

The pressure in the cuff 10 In the following step S17-4 is held in the second holding pressure P _{CH 2} which is set in advance. The second holding pressure P _CH2 is larger than the pulse wave stored in step S17-3 in order to detect the rate of change θ on the low pressure side of the envelope indicating the magnitude of the pulse wave in FIG. Is a pressure that can be collected and is set to, for example, about 25 to 30 mmHg. Next, also in step S17-5, it is determined whether or not two consecutively input pulse waves have the same magnitude. If the determination in step S17-5 is denied, the above-described steps S17-4 and subsequent steps are executed again. If the determination is affirmative, the amplitude values of the two pulse waves are changed to the second pulse in step S17-6. It is stored as a wave amplitude Am _2.
Then, in step S17-7, the first expression is obtained from Expression 2.
Pulse wave amplitude Am ₁ , second pulse wave amplitude Am ₂ , first holding pressure P _CH1 ,
The rate of change θ is calculated based on the second holding pressure P _CH2 .

[0048]

## EQU2 ## θ = (Am ₂ −Am ₁ ) / (P _CH2 −P _CH1 )

FIG. 10 shows the pressure change of the cuff 10 during the blood pressure monitoring period in this embodiment. That is, after the pressure of the cuff 10 is increased stepwise to the first holding pressure P _CH1 , the first holding pressure is maintained until two similar pulse waves are generated and the first pulse wave amplitude Am ₁ is stored. After the pressure is held at the pressure P _CH1 and then stepped up to the second holding pressure P _CH2, the second holding is performed until two similar pulse waves are generated and the second pulse wave amplitude Am ₂ is stored. It is maintained at the pressure P _CH2 . Then, in the present embodiment, the second holding pressure P _CH2 is made equal to the holding pressure P _CH, and step S2 in FIG.
Steps S1 to S22 become unnecessary, and in step S24, a systolic blood pressure value P _sysE and a diastolic blood pressure value P _diaE are estimated based on the second pulse wave amplitude Am ₂ .

According to the present embodiment, in addition to the same effects as described above, the first holding pressure _PCH1 and the second
Since the change rate θ of the rising portion of the envelope low pressure side is calculated based on the holding pressure P _CH2 , the change rate θ is accurately determined, and there is an advantage that blood pressure monitoring accuracy is improved. In the present embodiment, a pulse wave is detected when two similar pulse waves are input in a state where the pressure of the cuff 10 is kept constant during the blood pressure monitoring period. Has the advantage that blood pressure monitoring accuracy can be further improved. Also,
In the present embodiment, since the second holding pressure P _CH2 is made equal to the holding pressure P _CH , there is an advantage that the holding period for abnormality determination by the second abnormality determination means 60 does not need to be provided independently. Further, there is an advantage that steps S21 to S22 in FIG. 4 are not required.

FIG. 11 shows the judgment reference value θ._OOr P
_sysEOAnd P_diaEOPressure in relation to the set value of_CHTo
9 shows a main part of a flowchart of an embodiment to be changed.
In the present embodiment, as shown in FIG.
A judgment reference value setting key 46 functioning as a means 62 is provided.
And the above judgment reference value θ_OOr P_sysEOand
P_diaEOOperated to input the set value of. FIG.
In step SA1 of FIG.
The input value is read from the
Judgment used in step S18 or S25
Reference value θ_OOr P _sysEOAnd P_diaEOIs changed.
In the following step SA2, the holding of step S21 in FIG.
Pressure P_CHAlternatively, P in step S17-4 of FIG._CH2
Is actually obtained from the relationship stored in advance shown in FIG. 12, for example.
Set reference value θ_O, P_{sysE O}Or P_diaEO
Is changed based on the In the present embodiment, the above step S
A2 corresponds to the pressure value changing means 64. This implementation
According to the example, compression during blood pressure monitoring period by cuff 10
Has the advantage of being as low as possible.

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

[0053] For example, in the illustrated embodiment, the rate of change of the pulse wave amplitude from Equation 1 or Equation 2 for the cuff pressure P _C theta has been determined, for example, the pulse wave amplitude Am 7
The maximum value (dAm / dP _C ) _{max of the} rate of change until the value rises from the minimum value to the maximum value may be adopted as the rate of change θ.

Further, in the above-described embodiment, as shown in FIG.
_Although only _3M is held, the holding period _T3M may not be provided. In other words, the second determination is made based on the magnitude of the pulse wave detected during the holding period _T3M .
It does not matter if the abnormality determination means 60 is not provided.

Further, the holding pressures P _CH and P _{CH2 of the} above-described embodiment are used.
Was set to a pressure of about 20 to 30 mmHg,
The present invention is not limited to this. If the pressure is lower than the _mean blood pressure value P _{mean, a certain} effect can be obtained.
It is more preferable that the pressure is set lower than _{dia in} that blood pressure is not hindered.

In the above-described embodiment, the pulse wave is detected by filtering the pressure vibration of the cuff 10 for measuring blood pressure by the first band-pass filter 22 or the second band-pass filter 23. The present invention can be applied even if a cuff (inflation bladder) that is provided independently of the cuff 10 and compresses the artery is used.

The above is merely an embodiment of the present invention, and the present invention can be variously modified without departing from the gist thereof.

[Brief description of the drawings]

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

FIG. 2 is a functional block diagram illustrating a main part of a control function of the arithmetic and control circuit of FIG. 1;

FIG. 3 is a flowchart illustrating a part of a control operation of the arithmetic control circuit of FIG. 1;

FIG. 4 is a flowchart illustrating a part of a control operation of the arithmetic control circuit in FIG. 1;

FIG. 5 is a diagram showing a relationship used in the flowchart of FIG. 4;

FIG. 6 is a time chart for explaining a cuff pressure changed by the control operations of FIGS. 3 and 4;

7 is a diagram illustrating a rate of change θ of the magnitude of a pulse wave calculated in the control operation of FIG. 4;

FIG. 8 is a diagram illustrating an envelope connecting the amplitude values of pulse waves, which changes in relation to a change in blood pressure value.

FIG. 9 is a flowchart illustrating a main part of an operation according to another embodiment of the present invention.

FIG. 10 is a time chart for explaining the cuff pressure changed by the control operation of the embodiment of FIG. 9;

FIG. 11 is a flowchart illustrating a main part of an operation according to another embodiment of the present invention.

FIG. 12 is a diagram illustrating a relationship used in the embodiment of FIG. 11;

[Explanation of symbols]

 10: Cuff 50: Pulse wave detecting means 52: Blood pressure measuring means 54: Compression pressure controlling means 56: Change rate determining means 58: First abnormality determining means 60: Second abnormality determining means 62: Determination reference value setting means 64: Pressure Value changing means

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) A61B 5/022

Claims (8)

(57) [Claims] 1. A blood pressure monitoring device for monitoring a blood pressure value of a living body by changing a compression pressure of a cuff wound around a part of a living body, wherein a pulse generated in the cuff when the cuff is compressed is provided. Pulse wave detection means for detecting a wave; compression pressure control means for repeatedly changing the compression pressure of the cuff to a predetermined pressure value lower than the average blood pressure value of the living body after a predetermined rest period; and Rate-of-change determining means for determining a rate of change in the magnitude of the pulse wave with respect to a change in compression pressure of the cuff by the control means; and based on the rate of change determined by the rate-of-change determining means, the blood pressure value abnormality of the living body is determined. A blood pressure monitoring device, comprising: a first abnormality determination unit for determining. 2. The blood pressure measurement means for automatically measuring the blood pressure value of the living body according to a predetermined series of measurement operations when the first abnormality determination means determines that the blood pressure value of the living body is abnormal. The blood pressure monitoring device according to claim 1, wherein the blood pressure monitoring device includes: 3. The first abnormality determining means determines whether or not the magnitude of the pulse wave is lower than a predetermined criterion value, and determines whether the magnitude of the pulse wave is lower than the predetermined criterion value. The blood pressure monitoring device according to claim 2, wherein the blood pressure monitoring device determines that the blood pressure value of the living body is abnormally low. 4. The compression pressure control means changes the compression pressure of the cuff to a predetermined constant pressure value and thereafter maintains the pressure value at the constant pressure value for a predetermined holding period. The blood pressure monitoring device according to any one of claims 1 to 3, further comprising a second abnormality determination unit configured to determine an abnormal blood pressure value of the living body based on a magnitude of the pulse wave detected during the period. 5. The compression pressure control means increases the compression pressure of the cuff to a predetermined first holding pressure and holds the same, and then sets the second holding pressure to a value higher than the first holding pressure. The change rate determining means determines the rate of change of the magnitude of the pulse wave detected during the holding period of the first holding pressure and the holding period of the second holding pressure, respectively. Claims 1 to 3
Blood pressure monitoring device. 6. The blood pressure monitoring device according to claim 5, further comprising second abnormality determining means for determining an abnormal blood pressure value of the living body based on the magnitude of the pulse wave detected during the holding period of the second holding pressure. . 7. The blood pressure measurement means according to a predetermined series of measurement operations when at least one of the first abnormality determination means and the second abnormality determination means determines an abnormal blood pressure value of the living body. 7. The blood pressure monitoring device according to claim 4, wherein the blood pressure value of the living body is automatically measured. 8. The compression pressure control means changes the compression pressure of the cuff to a predetermined constant pressure value, and determines whether the first abnormality determination means sets a determination reference value to a desired value. 2. A reference value setting means, and a pressure value changing means for changing a constant pressure value changed by the compression pressure control means according to a judgment reference value set by the judgment reference value setting means. 7. The blood pressure monitoring device according to any one of items 1 to 7.