JPH0624524B2 - Blood pressure measurement 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 measuring device, and more particularly to a blood pressure measuring device for measuring a blood pressure value using a surface pressure sensor that presses on an artery on the surface of a living body.

[0002]

2. Description of the Related Art Conventionally, there is a cuff attached to a part of a living body in a wound state to press the part of the living body, and the cuff is sequentially sampled in the process of changing the compression pressure of the cuff. A blood pressure measuring device for non-invasively measuring a blood pressure value based on a pulse signal or a pulse wave signal is provided. According to such a blood pressure measuring device, a blood pressure close to the blood pressure value measured invasively is provided. The value can be measured.

[0003]

However, in the blood pressure measuring device using the above-mentioned cuff, for example, a part of the living body is relatively strongly tightened over the entire circumference by the cuff, so that the living body may feel pain. there were.

On the other hand, a blood pressure value, which is an absolute pressure in the artery, is used based on the pressure pulse wave detected by the surface pressure sensor that presses on the artery on the surface of the living body without using a cuff. Blood pressure measuring devices for non-invasive measurement of blood pressure have been studied, but sufficient measurement accuracy cannot be obtained and they have not yet been put to practical use.

The present invention has been made in view of the above circumstances, and an object thereof is to obtain a blood pressure value which is an absolute pressure in an artery by using a surface pressure sensor which presses on the artery on the surface of a living body. An object of the present invention is to provide a blood pressure measurement device that can measure blood pressure with suitable accuracy.

[0006]

As a result of various studies, the inventor of the present invention includes the pressure signal sequentially output from the surface pressure sensor in the process of crushing the artery by gradually changing the pressing force of the surface pressure sensor. Of the curves connecting the upper peaks and the lower peaks of each pressure pulse wave, a straight line that approximately represents a flat portion with a small change due to the change in the pressing force of the surface pressure sensor, and the flat portion of the curve The intersection with the straight line that approximately represents the inclined portion rising from the portion suitably corresponds to the time when the blood vessel of the artery is flattened, that is, the time when the pressing force of the surface pressure sensor slightly exceeds the intra-arterial pressure. At the same time, they have found that the systolic blood pressure value and the diastolic blood pressure value, which are the absolute pressures in the arteries, can be suitably measured based on this intersection.

The present invention has been made on the basis of such findings, and the gist thereof is to provide a pressing plane to be pressed onto an artery on the surface of a living body, as shown in the claim correspondence diagram of FIG. A surface pressure sensor having a pressure detection element provided, which outputs a pressure signal including a pressure pulse wave generated from the artery, and a pressing force adjusting means for adjusting the pressing force of the surface pressure sensor. The pressing force of the surface pressure sensor and the pressing force of the surface pressure sensor, which are successively output from the surface pressure sensor in the process of crushing the artery by gradually changing the pressing force of the pressure sensor,
Blood pressure for measuring at least one of the systolic blood pressure value and the diastolic blood pressure value based on at least one of the curve connecting the upper peak and the curve connecting the lower peak of each pressure pulse wave included in the pressure signal in the dimensional coordinates A measuring device, comprising: (a) first straight line determining means for determining a first straight line that approximately represents a flat portion of the curve, which changes little with a change in the pressing force of the surface pressure sensor; ) Second straight line determining means for determining a second straight line that approximately represents an inclined portion rising from the flat portion of the curve, and (c) the first straight line and the first straight line determined by the first straight line determining means. Blood pressure value determining means for determining the blood pressure value based on the intersection with the second straight line determined by the two straight line determining means.

[0008]

In the blood pressure measuring device of the present invention having such a configuration, the pressing force of the surface pressure sensor for pressing the artery in the living body is gradually changed and the surface pressure sensor is sequentially pressed in the process of crushing the artery. At least one of the curve connecting the upper peak and the curve connecting the lower peak of each pressure pulse wave included in the pressure signal in the two-dimensional coordinates of the magnitude of the output pressure signal and the pressing force of the surface pressure sensor The first straight line that approximately represents a flat portion, which changes little with the pressing force of the surface pressure sensor, is determined by the first straight line determining means, and an inclined portion that rises from the flat portion of the curve is approximated. The second straight line represented by the second straight line is determined by the second straight line determining means. Then, the blood pressure value determining means measures at least one of the systolic blood pressure value and the diastolic blood pressure value based on the intersection of the first straight line and the second straight line. Since the blood pressure value measured in this way is a suitable representation of the absolute pressure in the artery, the surface pressure sensor can be used to detect the internal pressure in the artery without causing pain to the living body due to the pressure of the cuff as in the conventional art. Provided is a blood pressure measurement device capable of measuring a blood pressure value that is an absolute pressure with suitable accuracy. In this case, since the surface pressure sensor locally presses on the artery on the surface of the living body and does not strongly tighten a part of the living body over the entire circumference like a cuff, pressing the surface pressure sensor The living body rarely feels pain.

As described above, according to the blood pressure measuring device of the present invention, the surface pressure sensor is used to obtain the blood pressure value, which is the absolute pressure in the artery, from the intersection of the first straight line and the second straight line in the curve with suitable accuracy. Therefore, it is possible to configure a continuous blood pressure measuring device that measures the blood pressure value for each beat based on the pressure signal from the surface pressure sensor without using a cuff. That is, the systolic blood pressure value and the diastolic blood pressure value measured from the intersection, and the upper peak value and the lower peak value of the pressure pulse wave included in the pressure signal detected after the pressing force of the surface pressure sensor is set to a predetermined pressing force. Based on the value, the relationship between the blood pressure value and the pressure pulse wave is obtained, and the blood pressure value is measured for each beat based on the pressure pulse wave that is sequentially detected by the set pressing force from the relationship. . According to such a non-invasive continuous blood pressure measuring device, for example, as described in Japanese Utility Model Application Laid-Open No. 1-171607, which was filed by the applicant of the present invention and published earlier,
Since it is not necessary to calibrate the blood pressure value measured for each beat of the pressure pulse wave from the pulse wave sensor (surface pressure sensor) based on the blood pressure value measured by the cuff, the cuff and the compression pressure of the cuff are adjusted. This eliminates the need for a compression pressure adjusting means or the like, which not only eliminates the pain caused to the living body due to the pressure of the cuff, but also has the effect that the device can be downsized and the cost of the device can be reduced.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a diagram showing an example of the blood pressure measuring device of the present invention, which is configured as a continuous blood pressure measuring device for continuously measuring the blood pressure value for each beat of the pressure pulse wave. In the figure, 10 is a housing having a cylindrical shape with a bottom, and the wearing band 1 with its open end facing the body surface 12 of the human body.
4 is detachably attached to the wrist 16. Inside the housing 10, the diaphragm 1
A surface pressure sensor 20 is provided so as to be capable of relative movement through the surface of the housing 10 and projectable from the open end of the housing 10. The housing 10, the diaphragm 18, and the surface pressure sensor 20 form a pressure chamber 22. A pressure fluid such as pressure air is supplied into the pressure chamber 22 from a fluid supply source 24 via a pressure regulating valve 26.
As a result, the surface pressure sensor 20 is pressed against the body surface 12 with a pressing force corresponding to the pressure in the pressure chamber 22.

The surface pressure sensor 20 comprises a plurality of pressure detecting elements (not shown) such as pressure sensitive diodes arranged in one direction on a pressing plane 28 of a semiconductor chip made of, for example, single crystal silicon. In the state where the arrangement direction of the pressure detecting elements is substantially orthogonal to the radial artery 32, the body surface 12
By being pressed onto the radial artery 32 of the
A pressure signal SM including a pressure pulse wave generated from 2 and transmitted to the body surface 12 is detected, and the pressure signal SM is not shown A
It is supplied to the control device 34 via the / D converter. The size and interval of the pressure detection elements are set so that a plurality of pressure detection elements can be located immediately above the radial artery 32.

The control device 34 includes a CPU, a ROM, and an R.
It is composed of a so-called microcomputer having an AM and an I / O port. The CPU executes signal processing while utilizing the storage function of the RAM according to a program stored in advance in the ROM, and the pressure regulating valve 26 is operated from the I / O port.
The drive signal SD is output to the pressure chamber 22 to adjust the pressure in the pressure chamber 22, and the pressure signal S in the process of gradually increasing the pressure in the pressure chamber 22.
While continuously detecting M, each pressure included in the pressure signal SM obtained in the process of changing the pressure in the pressure chamber 22 by the optimum pressure detecting element determined from the plurality of pressure detecting elements of the surface pressure sensor 20. The systolic blood pressure value SYS and the diastolic blood pressure value DIA are measured based on the curve connecting the upper peak and the lower peak of the pulse wave. Further, the CPU determines the optimum pressing force of the pressing force of the surface pressure sensor 20 according to the program stored in advance in the ROM and holds it at the optimum pressing force, and the optimum pressure detecting element detects the optimum pressing force at the optimum pressing force. The relationship between the pressure pulse wave and the blood pressure value based on the maximum and minimum values of the pressure pulse wave included in the detected pressure signal and the systolic blood pressure value SYS and the diastolic blood pressure value DIA measured based on the curve. On the other hand, from this relationship, the blood pressure values such as the systolic blood pressure value and the diastolic blood pressure value are determined for each beat based on the pressure pulse wave sequentially detected by the optimum pressure detection element at the optimum pressing force, and the I / O port is determined. The display / recording signal SI is output from the display unit 36 to sequentially display / record the determined blood pressure value on the display / recording device 36. In the present embodiment, the fluid supply source 24, the pressure regulating valve 26, the control device 34 and the like constitute pressing force adjusting means.

The operation of the blood pressure measuring device of this embodiment will be described below with reference to the flow chart shown in FIG.

First, in step S1, the pressure regulating valve 26 is controlled to start increasing the pressure in the pressure chamber 22 at a predetermined gentle constant speed. In the following step S2, the pressure signal SM is read and it is determined whether or not one pulse of the pressure pulse wave is detected. When one pulse of the pressure pulse wave is detected, step S
After the pressure signal SM including the detected pressure pulse wave and the pressure P in the pressure chamber 22 at that time are stored in 3, the step S4 is executed. This step S4
Then, it is judged whether or not the pressure P in the pressure chamber 22 has reached a predetermined target pressure Pm (for example, a pressure of about 200 mmHg). If this determination is negative, steps S2 to S4 are repeatedly executed, but if affirmative, step S5 is executed.

In step S5, after the pressure increase in the pressure chamber 22 is stopped, for example, when the pressure pulse wave with the maximum amplitude is detected in the pressure increasing process in the pressure chamber 22, the pressure chamber 2 is detected.
The pressure P in 2 is determined as the pressure corresponding to the optimum pressing force of the surface pressure sensor 20, and the pressing force of the surface pressure sensor 20 is held at the optimum pressing force. In the following step S6,
For example, of the plurality of pressure detection elements of the surface pressure sensor 20, the one that has detected the pressure pulse wave with the maximum amplitude is determined as the optimum pressure detection element. Here, FIG. 4 shows a curve connecting the upper peaks (hereinafter, referred to as an upper peak curve) and a curve connecting the lower peaks (hereinafter, referred to as an upper peak curve) of each pressure pulse wave detected by the optimum pressure detecting element in the pressure increasing process in the pressure chamber 22. , A lower peak curve) and an amplitude change curve. Figure 4
In the figure, the horizontal axis indicates the pressing force of the pulse wave sensor 20, the vertical axis indicates the magnitude and amplitude of the pressure signal SM, and the magnitude and amplitude of the pressure signal SM on the vertical axis are expressed in pressure units (mmHg). .

Next, in step S7, as shown in FIG. 4, a first straight line a, which approximately represents a flat portion of the above-mentioned upper peak curve, which changes little with the pressing force change, is determined.
Further, the first straight line b, which approximately represents the flat portion of the lower peak curve, which changes little with the pressing force change, is determined. In step S8, the second straight line c that approximately represents the sloped portion of the upper peak curve rising from the flat portion is determined, and the sloped portion of the lower peak curve rising from the flat portion is determined. A second straight line d that is approximately represented is determined. In FIG. 4, the upper peak curve and the lower peak curve converge with each other as the pressure becomes higher on the second straight lines c and d, and when such convergence appears, the radial artery 32 is normally flatly crushed. It means that it is being done. In the following step S9,
Intersection e between the first straight line a and the second straight line c of the upper peak curve
The magnitude of the pressure signal SM in (see FIG. 4) is determined as the systolic blood pressure value SYS, and the pressure signal SM at the intersection point f (see FIG. 4) between the first straight line b and the second straight line d of the lower peak curve is determined. Is determined as the diastolic blood pressure value DIA. In this embodiment, the step S7 corresponds to the first straight line determining means, the step S8 corresponds to the second straight line determining means, and the step S8 corresponds to the blood pressure value determining means.

Next, at step S10, one pulse of the pressure pulse wave is detected by the optimum pressure detecting element at the optimum pressing force, and the maximum and minimum values of the pressure pulse wave, that is, the upper peak and the lower peak of the pressure pulse wave are detected. The magnitudes of the pressure signals SM at the respective positions are determined, and the maximum and minimum values and the systolic blood pressure value SY determined at step S9 are determined.
The relationship between the pressure pulse wave (magnitude of the pressure signal SM) and the blood pressure value is determined based on S and the minimum blood pressure value DIA.

When the relationship between the pressure pulse wave and the blood pressure value is obtained in this way, continuous blood pressure measurement is started for each beat of the pressure pulse wave using this relationship. That is, step S11
Then, it is judged whether the pressure signal SM is read and one pulse of the pressure pulse wave is detected. When one beat is detected, the maximum value and the minimum value of the detected pressure pulse wave are determined in step S12, and then the maximum value and the minimum value of the determined pressure pulse wave are determined in step S13. The systolic blood pressure value and the diastolic blood pressure value are determined from the above relationship, and the determined blood pressure values are displayed / recorded on the display / recording device 36 in step S14. In the following step S15, a predetermined fixed time (for example, 15
It is determined whether or not (a time of about a minute) has elapsed, and if this determination is denied, the above steps S11 to S15 are repeatedly executed, so that each pulse of the pressure pulse wave is calculated using the above relationship. Blood pressure is measured at. on the other hand,
When the determination in step S15 is affirmative, the pressure in the pressure chamber 22 is exhausted in step S16, and then the process returns to step S1 to again perform the above-described upper peak curve and lower peak curve as described above. Blood pressure value SY
After S and DIA are newly determined and the relationship is updated, the blood pressure value is measured for each beat of the pressure pulse wave using the updated relationship.

As described above, according to this embodiment, the pressure signal SM continuously output from the surface pressure sensor 20 is included in the process of crushing the radial artery 32 by gradually increasing the pressing force of the surface pressure sensor 20. First straight line a of the upper peak curve of each pressure pulse wave
Blood pressure value SYS is measured based on the intersection point e between the second straight line c and the minimum blood pressure value based on the intersection point f between the first straight line b and the second straight line d of the lower peak curve of each pressure pulse wave. DI
A is measured. The intersections e and f correspond to the time point when the blood vessel of the radial artery 32 is flattened, that is, the time point when the pressing force of the surface pressure sensor 20 slightly exceeds the internal pressure of the radial artery 32. Since the blood pressure values SYS and DIA determined based on e and f suitably represent the absolute pressure in the radial artery 32, the surface pressure can be maintained without causing the human body to feel pain by pressing the cuff as in the conventional art. Sensor 20
Can be used to measure the blood pressure value, which is the absolute pressure in the radial artery 32, with suitable accuracy. In this case, the surface pressure sensor 20 locally presses on the radial artery 32 on the body surface 12 and does not strongly clamp a part of the living body over the entire circumference like a cuff, so the surface pressure sensor 20 Sensor 20
The human body hardly feels the pressure of.

Further, according to the present embodiment, the relation between the blood pressure value and the pressure pulse wave is obtained based on the relatively accurate blood pressure values SYS and DIA measured from the upper peak curve and the lower peak curve, and Since the blood pressure value can be suitably measured for each beat of the pressure pulse wave using the relationship, the relationship between the blood pressure value and the pressure pulse wave is obtained based on the blood pressure value measured using the cuff as in the conventional case. Since the cuff and the compression pressure adjusting means for adjusting the compression pressure of the cuff are not needed, the non-invasive continuous blood pressure measuring device can be downsized and the cost of the device can be suitably reduced. be able to.

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

For example, in the above embodiment, the intersection point e between the first straight line a and the second straight line c of the upper peak curve of the pressure pulse wave by the optimum pressure detecting element and the first straight line b and the second straight line of the lower peak curve.
The systolic blood pressure value SYS and the diastolic blood pressure value DIA are measured based on the intersection point f with the straight line d, and the relationship between the pressure pulse wave and the blood pressure value is obtained based on these blood pressure values, but this is not always necessary. However, for example, the systolic blood pressure value SYS and the diastolic blood pressure value DIA are similarly measured for the two pressure detecting elements on both sides of the optimum pressure detecting element, and the average value of the systolic blood pressure values SYS by the three pressure detecting elements and The relationship may be obtained based on the average value of the lowest blood pressure value DIA.

Further, according to this embodiment, the systolic blood pressure value SYS measured from the upper peak curve and the lower peak curve is
And the relationship between the blood pressure value and the pressure pulse wave is determined based on the minimum blood pressure value DIA and the maximum value and the minimum value of the pressure pulse wave detected at the optimum pressing force, but this is not always necessary. SYS and DI from the above peak curve
Mean blood pressure value ME is measured based on the centroid of the waveform area of the pressure pulse wave detected at the optimum pressing force while measuring either one of A.
Determine AN, and then one of them SYS and DIA
It can also be configured to determine the relationship based on AN.

In the above embodiment, the blood pressure is measured for each beat of the pressure pulse wave from the relationship between the pressure pulse wave and the blood pressure value obtained based on the blood pressure value as the absolute pressure measured by using the surface pressure sensor 20. Although the continuous blood pressure measuring device that measures the value has been described, the blood pressure measuring device that measures only the blood pressure value as an absolute pressure may be used. In this case, only one of the systolic blood pressure value and the diastolic blood pressure value may be measured.

Further, in the above-described embodiment, a step of determining whether the upper peak curve and the lower peak curve of the pressure pulse wave are converged on the high pressure side is provided, and the blood pressure is measured only when they are converged. It can also be configured as follows. By doing so, there is an advantage that inaccurate blood pressure measurement can be prevented when the radial artery 32 is not crushed into a flat shape by escaping in the depth direction of the wrist 16, for example.

In the above embodiment, the optimum pressure detecting element of the surface pressure sensor 20 is selected from the plurality of pressure detecting elements that detects the pressure pulse wave having the maximum amplitude, but it is not always necessary. , For example, a pressure detection element having the smallest difference between the baseline level of the pressure pulse wave detected at the time of starting the pressure increase in the pressure chamber 22 and the baseline level of the pressure pulse wave detected at the time of increasing the pressure to a predetermined pressure. You may make it select as an optimal pressure detection element.

Further, in the above embodiment, the surface pressure sensor 20 is provided with a plurality of pressure detecting elements. However, even when a single pressure detecting element is provided, by applying the present invention, It is possible to obtain substantially the same effect as the above-mentioned embodiment.

Further, in the above embodiment, the systolic blood pressure value S is calculated based on the pressure signal SM obtained in the pressure increasing process in the pressure chamber 22.
Although YS and the diastolic blood pressure value DIA are determined, the blood pressure values may be determined based on the pressure signal SM obtained in the pressure reducing process in the pressure chamber 22.

Further, although the surface pressure sensor 20 is pressed on the radial artery 32 in the above embodiment, it may be pressed on an artery other than the radial artery, for example, the dorsalis pedis artery.

Besides, the present invention can be variously modified without departing from the spirit thereof.

[Brief description of drawings]

FIG. 1 is a diagram corresponding to a claim of the present invention.

FIG. 2 is a diagram showing an example of a blood pressure measurement device of the present invention, showing the configuration.

3 is a flow chart for explaining the operation of the apparatus of FIG.

FIG. 4 is an upper peak curve and a lower peak curve of each pressure pulse wave included in the pressure signal SM continuously detected by the optimum pressure detection element in the process of gradually increasing the pressing force of the surface pressure sensor in the flowchart of FIG. It is a figure which shows an example of such.

[Explanation of symbols]

12 body surface 20 surface pressure sensor {24 fluid supply source, 26 pressure regulating valve, 34 control device}
Pressing force adjusting means 28 Pressing plane 32 Radial artery Step S7 First straight line determining means Step S8 Second straight line determining means Step S9 Blood pressure value determining means

Claims (1)

[Claims] 1. A surface pressure sensor which has a pressure detecting element provided on a pressing plane pressed against an artery on the surface of a living body, and which outputs a pressure signal including a pressure pulse wave generated from the artery, and the surface. And a pressing force adjusting means for adjusting the pressing force of the pressure sensor,
In the process of crushing the artery by gradually changing the pressing force of the surface pressure sensor, the pressure signal is converted into the pressure signal at the two-dimensional coordinates of the magnitude of the pressure signal sequentially output from the surface pressure sensor and the pressing force of the surface pressure sensor. A blood pressure measuring device for measuring a blood pressure value of at least one of a systolic blood pressure value and a diastolic blood pressure value based on at least one curve of a curve connecting an upper peak of each pressure pulse wave and a curve connecting a lower peak thereof, wherein: First straight line determining means for determining a first straight line that approximately represents a flat portion of the curve, which changes little with a change in the pressing force of the surface pressure sensor; and an inclined portion that rises from the flat portion of the curve. Based on the intersection of the first straight line determined by the first straight line determination means and the second straight line determined by the second straight line determination means. Blood pressure measuring apparatus which comprises a blood pressure determining means for determining the blood pressure value.