JPH05261072A - Pressure pulse wave detector - Google Patents

Abstract

PURPOSE:To eliminate the degradation in the accuracy of measuring pressure pulse waves by a change in pressing conditions by determining a pressure difference between the pressure at the time of non-pressing detected by a pressure detecting element and the pressure at the time of pressing, by which the pressing state of a pulse wave sensor is easily decided. CONSTITUTION:A pulse wave detecting probe 26 has an air bag 30 made of expandable rubber mounted within the wall of a housing 28 and the pulse wave sensor 32 embedded with many pressure detecting means within a pressing surface 38 pressed toward the radial artery 18 within the wrist 10 of a living body in association with the expansion of this bag. The pressure pulse wave signals outputted from the pressure detecting elements are stored in a storage place 50a of a RAM 50. Similarly, the pressure pulse wave signals at the time of pressing are drawn and are stored in the storage place 50b of the RAM 50. The pressure difference DELTAP (=PD-P0) between the pressure R0 at the time of the non-pressing expressed by the pressure pulse wave signal at the time of the non-pressing and the pressure PD at the time of the pressing expressed by the pressure pulse wave signal at the time of pressing is calculated. The pressing state of the pulse wave sensor 32 by the air bag 30 is decided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure pulse wave detecting device of a type in which a pulse wave sensor having a plurality of pressure detecting elements arranged in one direction is pressed against an artery.

[0002]

2. Description of the Related Art A pulse wave sensor having a pressing surface in which a plurality of pressure detecting elements are arranged in one direction, and is pressed onto an artery on the surface of a living body so that the arrangement direction of the pressure detecting elements intersects with the blood vessel. And a pressing means for urging the pulse wave sensor toward the artery so that a part of the arterial wall of the pressure surface becomes flat, and the pressure detecting element is located in the vicinity of just above the artery. There is known a pressure pulse wave detection device of a type that detects a pressure pulse wave generated from an artery based on a pressure pulse wave signal output from the. For example, it is the one described in Japanese Utility Model Laid-Open No. 64-12505, which the applicant of the present application filed and published earlier. According to such a pressure pulse wave detecting device, since the pressure in the artery propagating through a part of the flattened artery wall is detected by the pressure detecting element, it is possible to obtain a value close to the pressure in the artery. There is.

[0003]

By the way, the pressure pulse wave detecting device as described above is mounted on the surface of the living body by a mounting band wound around a part of the living body or an adhesive means when the pressure pulse wave is detected. On the other hand, in order to optimize the pressing state of the pulse wave sensor, for example, the pressure pulse wave signal detected by the pressure detection element located immediately above the artery is pressed with a predetermined thrust so as to maximize the amplitude. The means is adapted to press. However, since the mounting state of the pressure pulse wave detection device on the living body surface easily changes due to body movement of the living body, etc., despite the pressing means biasing with a predetermined thrust,
Since the pressing state of the pulse wave sensor with respect to the artery changes due to such body movements, the measurement accuracy of the pressure pulse wave may not be obtained in some cases. Since the pressing means is configured to generate thrust by expansion of the diaphragm or air bag, for example, the thrust changes in relation to the protruding position of the pulse wave sensor even if the pressure supplied to it is constant. Is inevitable.

The present invention has been made in view of the above circumstances, and an object thereof is to easily determine that the pressing state of the pulse wave sensor with respect to the artery has changed due to body movement of the living body. It is to provide a pressure pulse wave detection device.

[0005]

SUMMARY OF THE INVENTION The gist of the present invention for achieving such an object is that a plurality of pressure detecting elements are arranged in one direction as shown in the gist of the invention of FIG. A pulse wave sensor that has a pressing surface and is pressed on an artery on the surface of the living body so that the arrangement direction of the pressure detecting elements intersects the artery, and the pressing surface is such that a part of the artery wall is flat. A pressure means for urging the pulse wave sensor toward the artery, and a pressure generated from the artery based on a pressure pulse wave signal output from one of the pressure detection elements located immediately above the artery. A pressure pulse wave detecting device for detecting a pulse wave, comprising: (a) a non-pressing pressure signal storage means for storing a non-pressing pressure signal output from the pressure detecting element in a non-contact state of the pressing surface. And (b) the pressing surface is in contact with the surface of the living body. In the pulse wave detection state, the pressure signal at the time of pressing to output the pressure signal at the time of pressing, which is output from one of the plurality of pressure detection elements located at a place deviating from directly above the artery, (c) the non-pressing A pressure difference calculating means for calculating a pressure difference between the non-pressing pressure represented by the time pressure signal and the pressing pressure represented by the pressing pressure signal, and (d) based on the pressure difference calculated by the pressure difference calculating means, And a determining unit that determines the pressed state of the pulse wave sensor by the pressing unit.

[0006]

With this configuration, the non-pressing-time pressure signal storage means stores the non-pressing-time pressure signal, the pressing-time pressure signal collecting means collects the pressing-time pressure signal, and the non-pressing-time pressure signal represents The pressure difference calculation means calculates the pressure difference between the pressing pressure and the pressing pressure represented by the pressing pressure signal. Then, the determining means determines the pressing state of the pulse wave sensor by the pressing means based on the pressure difference calculated by the pressure difference calculating means.

[0007]

As described above, the pressing state of the pulse wave sensor by the pressing means can be easily determined based on the pressure difference between the non-pressing pressure and the pressing pressure detected by the pressure detecting element. The pressure pulse wave detection can be stopped or the optimum pressing force determination operation can be restarted, and the deterioration of the pressure pulse wave measurement accuracy due to the change in the pressing condition can be eliminated.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A detailed description will be given below with reference to the drawings showing an embodiment of the present invention.

In FIG. 2, a band 16 having an adhesive sheet 12 on the inner peripheral surface and a detachable outer peripheral fastener 14 on the outer peripheral surface is attached around the wrist 10 of the living body. A through hole 20 is formed in a portion of the band 16 located right above the radial artery 18. Then, a pulse wave detection probe 26 having a pair of fixing bands 24 having an inner peripheral fastener 22 removably adhered to the outer peripheral fastener 14 on the inner peripheral surface thereof is fixed to the band 16. ing.

The pulse wave detection probe 26 includes a first housing 28 having a flat rectangular container shape, and an inflatable rubber air bag 3 mounted on an inner wall of the first housing 28.
0 and the wrist 10 of the living body related to the inflation of the air bag 30.
Pulse wave sensor 32 pressed toward the radial artery 18 inside
And a second housing 34 connected to the first housing 28 on its lateral side. In the second housing 34, a preamplifier (not shown), a power regulator for supplying power to the bridge, and a multiplexer 41 described later are provided.
Are accommodated.

When the air bag 30 is inflated, the pulse wave sensor 32 is projected from the opening inside the first housing 28, and the flat projection 36 of the pulse wave sensor 32 is passed through the through hole 20 of the wrist 10. It is designed to be pressed against the skin surface. In the present embodiment, the air bag 30 functions as a pressing unit that presses the pulse wave sensor 32 against the body surface. FIG. 3 shows the relationship between the thrust F of the air bag 30 and the air pressure supplied thereto, and FIG. 4 shows the thrust F of the air bag 30 when a constant air pressure, for example, 100 mmHg is supplied. The relationship with the moving stroke of the pulse wave sensor 32 is shown.

The pressing surface 38, which is the end surface of the flat protrusion 36 of the pulse wave sensor 32, is, for example, as shown in FIG.
About 60 pressure detection elements 40 are arranged in one direction, and the pressure detection element 40 detects the pressure pulse wave generated from the radial artery 18. FIG. 6 is a so-called tonogram, in which the solid line indicates the magnitude of the signal output from each pressure detection element 40 during systole, and the one-dot chain line from each pressure detection element 40 during diastole. The magnitude of the output signal is shown.

The pulse wave sensor 32 has the same structure as that disclosed in, for example, Japanese Patent Application Laid-Open No. 3-15440, which was filed and filed by the present applicant earlier. Each of the bridges is composed of a pressure-sensitive resistor formed in the diaphragm of the semiconductor chip by an integrated circuit technique, and is arranged at a pitch of, for example, about 0.2 mm. The pulse wave detection probe 26 is fixed so that the arrangement direction of the pressure detection elements 40 is a direction intersecting with the radial artery 18, so that a sufficient number of pressure detection elements are provided directly above the radial artery 18. 40 can be positioned.

The pressure pulse wave signal output from the pressure detecting element 40 is a multiplexer 41 and an A / D converter 42.
Through the electronic control unit 44. The electronic control unit 44 includes a CPU 46, a ROM 48, a RAM 50, an output interface 52, etc.
While using the temporary storage function of the pressure control valve 58, the input signal is processed according to the program stored in the ROM 48 in advance, and the pressure adjusting valve 58 is processed through the output interface 52 and the D / A converter 54.
And the multiplexer 41 via the output interface 52. The pressure regulating valve 58 is
The pressure of the gas fed under pressure from a pressure source 60 such as an air pump or a gas cylinder is adjusted according to a command signal from the electronic control unit 44, and the gas is supplied into the air bag 30. Further, the electronic control unit 44 continuously monitors the blood pressure value and displays it on the display 56.
To display.

Further, the electronic control unit 44 drives the pressure regulating valve 68 via the D / A converter 64, so that the compression pressure of the cuff 66 wound around the arm of the living body is well known. The pressure sensor 70 detects the pressure of the cuff 66 and the pressure vibration generated therein, that is, the cuff pulse wave in the course of the change of the compression pressure, and the electronic control unit 44 through the A / D converter 72. To enter. Then, the blood pressure value is determined based on the change in the cuff pulse wave.

Hereinafter, a main part of the control operation by the electronic control unit 44, that is, a monitor routine for monitoring the arterial pressure in the radial artery 26 or the arterial pressure waveform based on the pressure pulse wave signal from the pressure detecting element 40 will be described. A description will be given according to the flowchart of FIG.

The routine of FIG. 7 is started in response to the operation of a start push button (not shown). After performing well-known initial processing in step SM1, in step SM2, in order to perform zero calibration of each pressure detection element 40, in the non-contact state of the pressing surface 38 before the pressure sensor 32 is pressed, A signal from the pressure detection element 40 is read, and the read signal values are stored in predetermined storage locations 50a of the RAM 50 as zero points of the detected pressure of each pressure detection element 40.

In the routine for determining the optimum pressing force in the subsequent step SM3, the pulse wave sensor 32 is pressed by the air bladder 30 to the extent that the blood flow in the radial artery 18 is stopped, and each pressure detecting element 40 is pressed by the pressure detecting element 40 in the process of pressing the artery. The optimum pressure value HDP is determined based on the obtained pressure pulse wave signal. As the HDP determination method, for example, there is a method of determining the pressure at which the amplitude of a predetermined pressure pulse wave signal that changes in the pressing process is the maximum as the optimum pressing force, or the method described in Japanese Patent Laid-Open No. 2-109540. Adopted. Then, in the subsequent step SM4, the pressure regulating valve 58 is regulated so that the optimum pressing force is maintained, and a constant air pressure is supplied into the air bag 30.

Next, in step SM5, the signal input element is determined. That is, of the 60 pressure detection elements 40, the pressure detection element 40 to be signal-input to the electronic control unit 44 is selected, and the pressure pulse wave signal output from the pressure detection element 40 is output to the electronic control unit 44.
The multiplexer 41 is driven by the electronic control unit 44 as input to. The above-mentioned selection is made by selecting the most suitable active element for monitoring the blood pressure or the pressure pulse wave, the element group of 3 to 7 adjacent to the active element, and other element groups not included in the element group. It is performed by determining the number of elements located at intervals of 2 to 3 or more.

In the subsequent step SM6, the blood pressure measurement by the cuff 66 is executed in a predetermined procedure to determine the maximum blood pressure value SYS _CF and the minimum blood pressure value DIA _CF of the living body. Next, in step SM7, the upper peak value P _UP and the lower peak value P _{DW of} the pressure pulse wave signal output from the active element of the pressure detection element 40 are changed in the magnitude of the pressure pulse wave signal from the active element. While the upper peak value P _UP and the lower peak value P are determined based on
_DW and systolic blood pressure value SYS obtained in step SM6 above
A relationship for monitoring the blood pressure value is created or updated based on the _CF and the minimum blood pressure value DIA _CF. That is,
The upper peak value P _UP and the systolic blood pressure value SYS _{CF are} set on the two-axis coordinates including the blood pressure value axis and the pressure value (pulse wave signal value) axis.
The relationship (straight line) that passes through the point that indicates the lower peak value P _DW and the minimum blood pressure value DIA _CF is obtained.

In step SM8, it is determined whether or not a pressure pulse wave signal representing one pulse wave is input from the active element of the pressure detection element 40, and the process is kept on standby until it is determined that it is input. When it is determined that a new pressure pulse wave signal is input, the blood pressure monitor value is determined and displayed on the display 56 in step SM9. That is, the systolic blood pressure value SYS _MO and the diastolic blood pressure value DIA _MO are calculated based on the upper peak value P _UP and the lower peak value P _DW of the new pressure pulse wave signal from the relationship created and updated in step SM7.
Is determined, the monitor values are displayed on the display unit 56 for each beat.

Next, at step SM10, the pressure pulse wave signal from the element belonging to the other element group apart from the active element of the pressure detecting element 40 is read and its diastolic value (lower peak value) P is read. _D is stored in the predetermined storage location 50b of the RAM 50. In the following step SM11, the pressure difference ΔP (= P _D −P ₀ ) which is the difference between the value P ₀ at the time of zero calibration stored in the step SM1 and the value P _D stored in the step SM10 is calculated. It For ease of understanding, an example of the pressure difference ΔP is shown in FIG.

Then, in step SM12, the pressure difference ΔP is the initial value ΔP ₀ immediately after the optimum HDP is determined.
A preset range for, for example, its initial value Δ
It is determined whether the range of 10% around P ₀ is exceeded. That is, the change amount of the pressure difference ΔP from the beginning is 10
It is determined whether or not the percentage is exceeded. This step SM12
If the determination is positive, the wrist 1 of the pulse wave sensor 32
Since the pressing condition for 0 has changed, the steps from SM3 onward are executed and the optimum HDP determination operation is executed again. Even if the supply pressure to the air bladder 30 is constant, if the fixed state of the first housing 28 changes due to body movement or the like and the movement stroke of the pulse wave sensor 32 with respect to the first housing 28 changes, the thrust force toward the radial artery 18 Changes, and the pulse wave detection condition deviates from the optimum state.

If the determination in step SM12 is negative, in step SM13 it is determined whether or not the active element is appropriate based on the pulse wave signals from a plurality of element groups adjacent to the active elements up to that point. Is judged. For example, it is determined whether or not the pressure pulse wave signal from the active element up to that point has the maximum amplitude value among the pressure pulse wave signals from the plurality of element groups. If the determination in step SM13 is affirmative, step SM
15 is directly executed, but if negative, the active element is changed to a new one in step SM14, and signals from a plurality of element groups adjacent to the new active element are selected. Then, step SM15 is executed. Step SM15
Then, it is determined whether or not a stop push button (not shown) has been operated, and if the determination is negative, then step SM8 is executed.
The following is executed, but if the result is affirmative, this routine is terminated.

As described above, according to the present embodiment, the pressure pulse wave signal output from the pressure detecting element 40 in the non-pressed state is stored in the storage location 50a corresponding to the non-pressed pressure signal storage means. By the step SM10 corresponding to the hour pressure signal collecting means, the pressure pulse wave signal at the time of pressing is collected,
The pressure difference ΔP between the non-pressing pressure P ₀ represented by the pressure pulse wave signal when not pressed and the pressing pressure P _D represented by the pressure pulse wave signal when pressing
(= P _D -P ₀₎ is calculated in step SM11 that corresponds to the pressure difference calculation means. Then, in step SM12 corresponding to the determining means, the pressing state of the pulse wave sensor 32 by the air bag 30 is determined based on the pressure difference ΔP.

Therefore, the pressing state of the pulse wave sensor 32 by the air bag 30 is easily determined based on the pressure difference ΔP between the non-pressing pressure P ₀ and the pressing pressure P _D detected by the pressure detecting element 40. Therefore, the detection of the pressure pulse wave or the restart of the optimum pressing force determination operation can be automatically performed, and the deterioration of the pressure pulse wave measurement accuracy due to the change of the pressing condition can be eliminated.

Further, according to the present embodiment, among the many pressure detecting elements 40, the active element and a plurality of element groups adjacent to the active element and the two or more element groups not included in the active element group are arranged at intervals. Since the input is limited to the signal input from the device, the load of signal processing in the electronic control unit 44 is reduced.

Further, according to the present embodiment, the band 16 is checked while accurately confirming the position of the radial artery 18 through the through hole 20.
By attaching the pulse wave sensor 32 to the wrist 10 and then fixing the pulse wave detection probe 26 to the band 16, there is an advantage that the pulse wave sensor 32 can be easily and accurately attached right above the radial artery 18.

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, step S
If the determination of M12 is affirmative, the steps SM3 and below were executed to calibrate the optimum HDP operation automatically, but simply stop the continuous blood pressure monitor to display an abnormality. May be.

Further, in step SM12 of the above-described embodiment, the abnormality of the pressed state is determined based on the pressure difference ΔP, but the pressure pulse wave signal value read from the pressure detecting element 40 in step SM10 is a calibration value. If so, the abnormality in the pressed state may be determined based on the calibration value.

Further, in the above-mentioned embodiment, the air bag 30 is used as the pressing means, but another variable volume type actuator such as a diaphragm or a bellows may be used.

Further, the band 16 of the above-mentioned embodiment may have an adhesive silicone sheet having a high coefficient of friction with the skin on its inner peripheral surface, and both ends thereof may be fastened by metal fittings. ..

Further, although the pressure source 60 in the above-described embodiment is for pumping gas, it may be for pumping an incompressible fluid such as water or oil.

The above is merely an embodiment of the present invention, and the present invention can be modified in various ways without departing from the spirit of the invention.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a configuration of a main part of the present invention.

FIG. 2 is a block diagram illustrating a configuration of an exemplary embodiment of the present invention.

FIG. 3 is a diagram illustrating a relationship between a supply pressure of an air bladder which is a pressing unit of FIG. 2 and a thrust generated thereby.

4 is a diagram for explaining the relationship between the moving stroke of the pulse wave sensor of FIG. 2 and the thrust of its pressing surface.

5 is a front view illustrating a pulse wave detecting element arranged on a pressing surface of the pulse wave sensor of FIG.

FIG. 6 is a diagram showing a tonogram obtained by the pulse wave sensor of FIG. 2.

FIG. 7 is a flowchart illustrating a main part of operation of the electronic control device of FIG.

[Explanation of symbols]

 18 Radial artery 30 Air bag (pressing means) 32 Pulse wave sensor 38 Pressing surface 40 Pressure detecting element 50a Storage location (pressure signal storing means when not pressed) Step SM10 Pressing pressure signal sampling means SM11 Pressure difference calculating means Step SM12 Judgment means

Claims (1)

[Claims] 1. A pulse wave sensor having a pressing surface in which a plurality of pressure detecting elements are arranged in one direction, and pressed on an artery on the surface of a living body so that the arrangement direction of the pressure detecting elements intersects the artery. And a pressing means for urging the pulse wave sensor toward the artery so that the pressing surface makes a part of the artery wall flat, and the pressure detecting element is positioned in the vicinity of just above the artery. Is a pressure pulse wave detection device of the type that detects the pressure pulse wave generated from the artery based on the pressure pulse wave signal output from the, which is output from the pressure detection element in the non-contact state of the pressing surface. A non-pressing pressure signal storage means for storing a non-pressing pressure signal, and a pulse pressure detection state in which the pressing surface is in contact with the surface of the living body, out of the plurality of pressure detecting elements from directly above the artery. When pressed from the one located in the place A pressing pressure signal collecting means for collecting a force signal, a pressure difference calculating means for calculating a pressure difference between the non-pressing pressure represented by the non-pressing pressure signal and the pressing pressure represented by the pressing pressure signal, and the pressure A pulse wave detecting device, comprising: a determining unit that determines the pressing state of the pulse wave sensor by the pressing unit based on the pressure difference calculated by the difference calculating unit.