JP7445518B2 - automatic blood pressure measuring device - Google Patents

Description

TECHNICAL FIELD The present invention relates to an automatic blood pressure measuring device equipped with a compression band that is wrapped around a compressed body part such as an arm or an ankle of a living body.

It is equipped with a compression band that is wrapped around the compressed part of the living body, and in the process of changing the compression pressure of the compression band, pulse waves, which are pressure vibrations within the compression band, are extracted sequentially, and based on changes in the pulse wave, the body's body is detected. 2. Description of the Related Art Among automatic blood pressure measuring devices for determining blood pressure values, one is known that uses a compression band having a plurality of inflation bags connected in the width direction and each having an independent air chamber that compresses a compressed part of a living body. For example, that is what is described in Patent Document 1. In Patent Document 1, the plurality of inflation bags that are independent air chambers arranged in the width direction are referred to as an upstream inflation bag, an intermediate inflation bag, and a downstream inflation bag.

In the automatic blood pressure measuring device described in Example 1 of Patent Document 1, during the process in which the compression pressure by the compression cuff is lowered from a value higher than the systolic blood pressure value, the peak of the pulse wave obtained from the intermediate inflation bag is A blood pressure value determination algorithm is used that determines the compression pressures at points where the connecting envelope shows a sudden increase and a point where the envelope shows a sudden drop as the systolic blood pressure value and the diastolic blood pressure value. In addition, in the automatic blood pressure measuring device described in Example 2 of Patent Document 1, the amplitude of the pulse wave obtained from the downstream inflation bag during the process in which the compression pressure by the compression cuff is lowered from a value higher than the systolic blood pressure value. A systolic blood pressure value determination algorithm is used that determines the systolic blood pressure value based on a change in the ratio between the pulse wave amplitude value and the amplitude value of a pulse wave obtained from an expansion bag located upstream of the downstream expansion bag. In addition, during the process in which the compression pressure by the compression band is lowered from a value higher than the systolic blood pressure value, the pulse wave obtained from the downstream inflation bag and the pulse wave obtained from the inflation bag located upstream of the downstream inflation bag are compared. A diastolic blood pressure value determination algorithm is used that determines the diastolic blood pressure value based on changes in phase difference related information (time difference, pulse wave propagation velocity) between the waves.

Japanese Patent Application Publication No. 2012-071059

However, during the process in which the compression pressure by the compression band is lowered from a value higher than the systolic blood pressure value, the pulse wave obtained from the downstream inflation bag and the pulse wave obtained from the inflation bag located upstream of the downstream inflation bag. Information related to the phase difference between the waves (time difference, pulse wave propagation velocity) changes as the reflected waves from the point where the diameter of the arterial blood vessel changes are superimposed. It was hard to say that it was a clear change phenomenon that could be stably recognized. For this reason, the automatic blood pressure measuring device described in Patent Document 1 may not be able to accurately determine the diastolic blood pressure value based on the above-mentioned phase difference related information.

An object of the present invention is to provide an automatic blood pressure measuring device that can accurately determine the diastolic blood pressure value of a living body using reflected wave information contained in a pulse wave obtained from an intermediate inflation bag.

With the above circumstances as a background, the present inventor has developed a triple cuff that has an upstream inflation bag, an intermediate inflation bag, and a downstream inflation bag that are connected in the width direction and can independently compress a living body. When comparing and examining the cuff pulse waves obtained independently from the inflation bag, we found that in the process of lowering the compression pressure by the compression band from a value higher than the systolic blood pressure value, the pressure from the upstream inflation bladder, intermediate inflation bladder, and downstream inflation bladder Of the first-order differential waveforms of the upstream pulse wave, intermediate pulse wave, and downstream pulse wave obtained from the I found out. The characteristic change is related to a decrease in compression pressure of the reflected wave propagating upstream from the point where the cross-sectional area of the arterial blood vessel changes at the downstream end of the downstream inflation bag in the pulse wave propagation path. It is presumed that this is due to attenuation. The present invention has been made based on this knowledge.

That is, the gist of the first invention is as follows: (a) independent upstream inflation bags and intermediate inflation bags that are wrapped around a pressured part of a living body and are connected in the width direction to respectively compress the pressured part of the living body; , and a compression band having a downstream inflation bag and compressing an arterial blood vessel in the compressed region with the same compression pressure by the upstream inflation bladder, the intermediate inflation bladder, and the downstream inflation bladder, respectively. In the blood pressure measuring device, (b) in the process of changing the compression pressure on the compressed area by the compression band, an intermediate pressure vibration that is included in the compression pressure in the intermediate expansion bag and synchronized with the heartbeat of the living body; (c) a pulse wave extraction section that extracts a pulse wave; The above when the magnitude or amplitude of the secondary peak wave of the first derivative waveform of the intermediate pulse wave, on which the reflected wave reflected upstream from the point where the cross-sectional area changes is superimposed, is less than a preset determination threshold. The present invention further includes a diastolic blood pressure value determination unit that determines the diastolic blood pressure value of the living body based on the compression pressure of the compression band.

According to the automatic blood pressure measuring device of the first invention, in the process in which the compression pressure of the compression band is lowered from a value higher than the systolic blood pressure value, the cross-sectional area of the arterial blood vessel is lowered below the downstream end of the downstream inflation bag. The compression band when the magnitude or amplitude of the secondary peak wave of the first-order differential waveform of the intermediate pulse wave, on which the reflected waves reflected upstream from the point where the change changes, is less than a preset determination threshold. The apparatus includes a diastolic blood pressure value determination unit that determines a diastolic blood pressure value of the living body based on the compression pressure of the living body. Thereby, it is stably confirmed that the reflected wave that is reflected upstream from the point where the cross-sectional area of the arterial blood vessel changes under the downstream end of the downstream inflation bag and is superimposed on the intermediate pulse wave has been attenuated by a predetermined amount or more. Since the determination is made, the accuracy of determining the diastolic blood pressure value of the living body is improved.

The gist of the second invention is as follows: (a) an independent upstream inflation bag and an intermediate inflation bag that are wrapped around a pressured part of a living body and are connected in the width direction to compress each of the pressured parts of the living body; Automatic blood pressure measurement comprising a compression band having a downstream inflation bag and compressing an arterial blood vessel in the compressed region with the same compression pressure by the upstream inflation bag, the intermediate inflation bag, and the downstream inflation bag, respectively. (b) In the process of changing the compression pressure on the compressed site by the compression band, an intermediate pulse wave, which is a pressure vibration synchronized with the heartbeat of the living body, included in the compression pressure in the intermediate expansion bag; (c) a cross-sectional area of the arterial blood vessel below the downstream end of the downstream inflation bag during the process in which the compression pressure of the compression band is lowered from a value higher than the systolic blood pressure value; The compression band when the waveform for a predetermined period after the first maximum minimum wave in the second derivative waveform of the intermediate pulse wave, on which the reflected waves reflected upstream from the point where the change occurs, no longer intersects the baseline indicating zero. and a diastolic blood pressure value determination unit that determines the diastolic blood pressure value of the living body based on the compression pressure of the living body. As a result, it is stably determined that the waveform after the first maximum and minimum waveform of the second-order differential waveform of the intermediate pulse wave no longer intersects the baseline indicating zero , so the accuracy of determining the diastolic blood pressure value of the living body is increased. It will be done.

The gist of the third invention is that in the first invention or the second invention, the pulse wave extracting section extracts a frequency of 45 Hz, preferably 30 Hz, more preferably 30 Hz from the signal representing the compression pressure within the intermediate inflation bag. It has an upper limit cutoff frequency of 25 Hz, and more preferably 20 Hz, and is subjected to a low-pass filter process that passes frequency components lower than the upper limit cutoff frequency, so that the pressure vibration contained in the compression pressure in the intermediate inflation bag is The intermediate pulse wave is extracted. As a result, an intermediate pulse wave that clearly includes features indicating the influence of reflected waves can be obtained, so that the accuracy of determining the diastolic blood pressure value of the living body can be improved.

FIG. 1 is a block diagram illustrating the configuration of an automatic blood pressure measuring device that is an embodiment of the present invention. FIG. 2 is a diagram illustrating the compression band of FIG. 1 with a part of the outer circumferential surface cut away. FIG. 3 is a plan view showing an upstream inflation bladder, an intermediate inflation bladder, and a downstream inflation bladder provided in the compression band of FIG. 2. FIG. FIG. 4 is a sectional view taken along line IV-IV in FIG. 3, showing the upstream inflation bag, intermediate inflation bag, and downstream inflation bag cut in the width direction. 2 is a functional block diagram for explaining main parts of control functions provided in the electronic control device of FIG. 1. FIG. 6 is a time chart illustrating a main part of compression pressure control operation by the cuff pressure control section of FIG. 5. FIG. Pulse wave waveforms extracted from the compression pressures of the upstream expansion bag, intermediate expansion bag, and downstream expansion bag by the pulse wave extraction unit in FIG. 5 in a compression state with compression pressure sufficiently higher than the systolic blood pressure value; FIG. 6 is a diagram showing a first-order differential waveform of a pulse wave calculated by the first-order differential waveform calculating section of FIG. 5; 8 is a diagram showing a pulse wave waveform in a compression state with a compression pressure lower than that in FIG. 7 and a first-order differential waveform of the pulse wave. FIG. FIG. 9 is a diagram showing a pulse wave waveform in a compression state with a compression pressure lower than that in FIG. 8 and a first-order differential waveform of the pulse wave. 10 is a diagram showing a waveform of a pulse wave in a compressed state near the diastolic blood pressure value of the living body, which is lower than that in FIG. 9, and a first-order differential waveform of the pulse wave. FIG. 11 is a diagram showing a waveform of a pulse wave in a compression state with a compression pressure lower than that in FIG. 10 and a first-order differential waveform of the pulse wave. FIG. FIG. 6 is a diagram showing a flowchart illustrating a main part of the blood pressure measurement operation of the electronic control device of FIG. 5; 6 is a functional block diagram illustrating the functions of an electronic control device in another embodiment of the present invention, and corresponds to FIG. 5. FIG. Pulse wave waveforms extracted from the compression pressures of the upstream expansion bag, intermediate expansion bag, and downstream expansion bag by the pulse wave extraction unit of FIG. 13 in a compression state with compression pressure sufficiently higher than the systolic blood pressure value; FIG. 14 is a diagram showing a second-order differential waveform of a pulse wave calculated by the second-order differential waveform calculating section of FIG. 13; FIG. 15 is a diagram showing a pulse wave waveform in a compression state with a compression pressure lower than that in FIG. 14 and a second-order differential waveform of the pulse wave. FIG. 16 is a diagram showing a pulse wave waveform in a compression state with a compression pressure lower than that in FIG. 15 and a second-order differential waveform of the pulse wave. FIG. 17 is a diagram showing a pulse wave waveform in a compressed state near the diastolic blood pressure value of the living body, which is lower than that in FIG. 16, and a second-order differential waveform of the pulse wave. 18 is a diagram showing a pulse wave waveform and a second-order differential waveform of the pulse wave at a compression pressure lower than that in FIG. 17. FIG. 14 is a diagram illustrating a flowchart illustrating a main part of the blood pressure measurement operation of the electronic control device in FIG. 13, and corresponds to FIG. 12. FIG.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings. Note that in the following examples, the figures are simplified or modified as appropriate, and the dimensional ratios, shapes, etc. of each part are not necessarily drawn accurately.

FIG. 1 shows an automatic blood pressure measuring device 10 according to an example of the present invention, which includes a compression band 12 for an upper arm that is wrapped around a limb of a living body 14, such as an upper arm 16, which is a site to be compressed. This automatic blood pressure measuring device 10 generates blood pressure in response to a change in the volume of the artery 18 in the process of lowering the compression pressure PC of the compression band 12, which has been increased to a value sufficient to stop bleeding in the artery 18 in the upper arm 16. Pulse waves, which are pressure oscillations of compression pressure PC within the compression band 12, are sequentially extracted, and the systolic blood pressure value SBP and diastolic blood pressure value DBP of the living body 14 are measured based on information obtained from the pulse waves.

FIG. 2 is a diagram showing the compression band 12 with a part of the outer peripheral side nonwoven fabric 20a cut away. As shown in FIG. 2, the compression band 12 includes a belt-shaped outer bag 20 made of an outer peripheral side non-woven fabric 20a and an inner peripheral side non-woven fabric 20b made of synthetic resin fibers whose back surfaces are mutually laminated with synthetic resin such as PVC (polyvinyl chloride). , an upstream inflation bag 22 and an intermediate inflation bag which are housed sequentially in the width direction within the belt-shaped outer bag 20 and are made of a flexible sheet such as a soft polyvinyl chloride sheet and can independently compress the upper arm 16. 24, and a downstream expansion bag 26. This compression band 12 can be attached to and detached from the upper arm 16 by attaching and detaching a raised pile 28b attached to the end of the inner nonwoven fabric 20b to a hook and loop fastener 28a attached to the edge of the outer nonwoven fabric 20a. It is designed so that it can be installed.

The upstream inflation bag 22, the intermediate inflation bag 24, and the downstream inflation bag 26 each have independent air chambers that are connected in the width direction of the longitudinal compression band 12 and compress the upper arm 16, and each have a tube connection connector. 32, 34 and 36 are provided on the outer peripheral surface side. These tube connectors 32, 34, and 36 are exposed on the outer circumferential surface of the compression band 12 through the outer circumferential side nonwoven fabric 20a.

FIG. 3 is a plan view showing the upstream inflation bag 22, intermediate inflation bag 24, and downstream inflation bag 26 provided in the compression band 12, and FIG. 4 is a sectional view taken along the line IV-IV in FIG. . The upstream inflation bag 22, the intermediate inflation bag 24, and the downstream inflation bag 26 are for detecting pulse waves, which are pressure vibrations generated in response to changes in the volume of the artery 18 compressed by them. It is elongated. The upstream expansion bag 22 and the downstream expansion bag 26 are arranged adjacent to both sides of the intermediate expansion bag 24 . Further, the intermediate inflation bag 24 is disposed at the center of the compression band 12 in the width direction, sandwiched between the upstream inflation bag 22 and the downstream inflation bag 26. Note that when the compression band 12 is wrapped around the upper arm 16, the upstream inflation bag 22 and the downstream inflation bag 26 are positioned at a predetermined distance in the longitudinal direction of the upper arm 16, and the intermediate inflation bag 24 is It is arranged between the upstream inflation bag 22 and the downstream inflation bag 26 so as to be continuous in the longitudinal direction of the upper arm 16.

The intermediate expansion bag 24 has side edges with a so-called gusset structure on both sides. That is, at both ends of the intermediate inflation bag 24 in the longitudinal direction of the upper arm 16, that is, in the width direction of the compression band 12, there are a pair of flexible sheets that are folded in a direction that approaches each other so that the closer they get to each other, the deeper they become. Folding grooves 24f and 24g are formed, respectively. Ends 22a and 26a of the upstream expansion bag 22 and the downstream expansion bag 26 adjacent to the intermediate expansion bag 24 are inserted into the pair of folding grooves 24f and 24g, respectively. . As a result, the end 24a of the intermediate expansion bag 24 and the end 22a of the upstream expansion bag 22 are overlapped with each other, and the end 24b of the intermediate expansion bag 24 and the end 26a of the downstream expansion bag 26 are overlapped with each other. Since they have a mutually stacked structure, that is, an overlapping structure, when the upstream inflation bag 22, intermediate inflation bag 24, and downstream inflation bag 26 press the upper arm 16 with equal pressure, the pressure is also equal near their boundaries. distribution is obtained.

The upstream inflation bag 22 and the downstream inflation bag 26 also have side edges of a gusset structure at ends 22b and 26b on the opposite side from the intermediate inflation bag 24. That is, at the end 22b of the upstream inflation bag 22 opposite to the intermediate inflation bag 24, there is a folding groove 22f made of flexible sheets that is folded in the direction toward each other so that the closer they are to each other, the deeper the folding groove 22f is. It is formed. In addition, at the end 26b of the downstream inflation bag 26 opposite to the intermediate inflation bag 24, there is a folding groove 26g made of flexible sheets folded in the direction toward each other so that the closer they are to each other, the deeper the groove is. It is formed. In order to prevent the compression band 12 from protruding in the width direction, the sheet forming the folding groove 22f is inserted into the opposite side, that is, the intermediate inflation bag 24, through a connecting sheet 38 having a through hole arranged in the upstream inflation bag 22. connected to the side part. Similarly, the sheet constituting the folding groove 26g is connected to the opposite side, that is, the intermediate expansion bag 24 side, via a connection sheet 40 provided with a through hole arranged in the downstream expansion bag 26.

As a result, compression pressure against the artery 18 of the upper arm 16 can be obtained at the ends 22b and 26b of the upstream inflation bag 22 and the downstream inflation bladder 26 in the same way as in other parts, so effective compression in the width direction of the compression band 12 is achieved. The width will be equal to the width dimension. The width direction of the compression band 12 is about 12 cm, and since the three upstream inflation bags 22, the intermediate inflation bag 24, and the downstream inflation bladder 26 are arranged in the width direction, each of them is substantially 4 cm. It has no choice but to have a width dimension of approximately In order to sufficiently generate the compression function even with such a narrow width dimension, both ends 24a and 24b of the intermediate inflation bag 24, the end 22a of the upstream inflation bag 22, and the end 26a of the downstream inflation bag 26 are are overlapped with each other, and the ends 22b and 26b of the upstream expansion bag 22 and the downstream expansion bag 26 on the opposite side from the intermediate expansion bag 24 are the side edges of a so-called gusset structure. has been done.

Between the ends 22a and 26a of the upstream expansion bag 22 and the downstream expansion bag 26 on the intermediate expansion bag 24 side and the inner wall surfaces of the pair of folding grooves 24f and 24g into which they are inserted, that is, the opposing groove side surfaces. are interposed respectively with longitudinal shielding members 42n and 42m having stiffness anisotropy in which the bending stiffness in the width direction of the compression band 12 is higher than the bending stiffness in the longitudinal direction of the compression band 12. The shielding member 42n has a length similar to the overlapping dimension of the upstream inflation bag 22 and the intermediate inflation bag 24. Similarly, the shielding member 42m has a length similar to the overlapping dimension of the downstream expansion bag 26 and the intermediate expansion bag 24.

As shown in FIGS. 3 and 4, the outer circumference of the gap between the end 22a of the upstream expansion bag 22 and the folding groove 24f into which it is inserted, and the gap between the downstream expansion bag 26 Longitudinal shielding members 42n and 42m are respectively interposed in the outer peripheral side of the gap between the end portion 26a and the folding groove 24g into which it is inserted. In this embodiment, the shielding effect is greater in the gap on the outer circumference side than in the gap on the inner circumference side, so the longitudinal shielding members 42n and 42m are provided in the gap on the outer circumference side. and the gap on the inner peripheral side.

The shielding members 42n and 42m are arranged so that the plurality of flexible hollow tubes 44 made of resin are parallel to each other in the longitudinal direction of the upper arm 16 (that is, the width direction of the compression band 12), and In other words, the flexible hollow tubes 44 are arranged in series (in the longitudinal direction of the compression band 12), and the flexible hollow tubes 44 are connected directly by molding or adhesive, or indirectly through another member such as a flexible sheet such as an adhesive tape. It is constructed by interconnecting each other. The shielding member 42n is hung on a plurality of hanging sheets 46 provided at a plurality of locations on the outer circumferential side of the end 22a of the upstream inflation bag 22 on the intermediate inflation bag 24 side. Similarly, the shielding member 42m is hung on a plurality of hanging sheets 46 provided at a plurality of locations on the outer circumferential side of the end 26a of the downstream inflation bag 26 on the intermediate inflation bag 24 side.

Returning to FIG. 1, in the automatic blood pressure measuring device 10, an air pump 50, a rapid exhaust valve 52, and an exhaust control valve 54 are each connected to a main pipe 56. From the main pipe 56, there is a first branch pipe 58 connected to the upstream expansion bag 22, a second branch pipe 62 connected to the intermediate expansion bag 24, and a third branch pipe connected to the downstream expansion bag 26. The tubes 64 are each branched. The first branch pipe 58 includes a first on-off valve E1 for directly opening and closing between the air pump 50 and the upstream expansion bag 22. The second branch pipe 62 includes a second on-off valve E2 for directly opening and closing between the air pump 50 and the intermediate expansion bag 24. The third branch pipe 64 includes a third on-off valve E3 for directly opening and closing between the air pump 50 and the downstream expansion bag 26.

A first pressure sensor T1 for detecting the pressure value inside the upstream expansion bag 22 is connected to the first branch pipe 58, and a first pressure sensor T1 for detecting the pressure value inside the intermediate expansion bag 24 is connected to the second branch pipe 62. A second pressure sensor T2 is connected to the third branch pipe 64, a third pressure sensor T3 is connected to the third branch pipe 64, and a third pressure sensor T3 is connected to the main pipe 56, for detecting the pressure value inside the downstream inflation bag 26. A fourth pressure sensor T4 for detecting twelve compression pressures PC is connected. The electronic control device 70 is supplied with an output signal indicating the pressure value inside the upstream inflation bag 22, that is, the compression pressure PC1 of the upstream inflation bag 22, from the first pressure sensor T1, and an output signal indicating the pressure value PC1 of the upstream inflation bag 22 from the second pressure sensor T2. An output signal indicating the pressure value within the downstream inflation bag 26, that is, the compression pressure PC2 of the intermediate inflation bag 24 is supplied from the third pressure sensor T3, and an output signal indicating the pressure value within the downstream inflation bladder 26, that is, the compression pressure PC3 of the downstream inflation bladder 26. is supplied, and an output signal indicating the compression pressure PC of the compression band 12 is supplied from the fourth pressure sensor T4.

The electronic control device 70 is a so-called microcomputer including a CPU 72, a RAM 74, a ROM 76, a display device 78, an I/O port (not shown), and the like. This electronic control device 70 processes an input signal in accordance with a program stored in advance in a ROM 76 while a CPU 72 utilizes the storage function of a RAM 74, and in response to an operation of a blood pressure measurement start operation button 80, an electric air pump is activated. 50, by controlling the rapid exhaust valve 52, the exhaust control valve 54, the first on-off valve E1, the second on-off valve E2, and the third on-off valve E3, automatic blood pressure measurement control is executed, and the measurement results are displayed on the display device. 78.

FIG. 5 is a functional block diagram for explaining main parts of the control functions provided in the electronic control device 70. In FIG. 5, the electronic control device 70 functionally includes a cuff pressure control section 82, a pulse wave extraction section 84, a first-order differential waveform calculation section 86, a systolic blood pressure value determination section 88, a diastolic blood pressure value determination section 90, etc. There is. FIG. 6 is a time chart illustrating the main part of the compression pressure control operation of the compression band 12 by the cuff pressure control unit 82.

The cuff pressure control unit 82 closes the rapid exhaust valve 52 and the exhaust control valve 54 in response to the operation of the blood pressure measurement start operation button 80 shown in FIG. 3 by opening the on-off valve E3 and operating the air pump 50, the pressure of the compression cuff 12 is increased until the pressure reaches a target pressure value PCM that is sufficiently higher than the systolic blood pressure value SBP of the living body 14, for example, 180 mmHg. The compression pressure PC for 14 is rapidly increased.

Next, the cuff pressure control unit 82 repeatedly opens the exhaust control valve 54 at a predetermined cycle for a predetermined period of time, so that the compression pressure PC of the compression cuff 12 becomes a pressure sufficiently lower than the diastolic blood pressure value of the living body 14, for example, 30 mmHg. The compression cuff 12 is compressed at a preset pressure lowering rate so that a plurality of step pressures P1, P2, P3, ... Px are sequentially formed until the preset measurement end pressure value PCE is reached. The pressure PC is gradually lowered in steps.

The cuff pressure control unit 82 uses the rapid exhaust valve 52 to inflate the upstream inflation bag 22, the intermediate inflation bladder 24, and the downstream inflation bag when the compression pressure PC of the compression band 12 becomes smaller than the measurement end pressure value PCE. The pressure inside each bag 26 is evacuated to atmospheric pressure. In the compression band 12 controlled in this way, the upstream inflation bag 22, the intermediate inflation bag 24, and the downstream inflation bag 26 compress the living body 14 with the same compression pressure PC, but in FIG. 6, the fourth pressure sensor The compression pressure PC of the compression band 12 detected by is shown.

The pulse wave extraction unit 84 detects the first pressure sensor T1 and the second pressure in a state where the compression pressure PC of the compression band 12 is maintained at each step pressure P1, P2, P3, ... Pressure synchronized with the heartbeat of the living body that is superimposed on each compression pressure PC1, PC2, and PC3 of the upstream inflation bag 22, intermediate inflation bag 24, and downstream inflation bag 26 based on output signals from the sensor T2 and the third pressure sensor T3. Pulse wave signals SM1, SM2, and SM3 indicating pulse waves that are fluctuations are sequentially extracted and stored.

Specifically, the frequency of the output signals from the first pressure sensor T1, the second pressure sensor T2, and the third pressure sensor T3 is, for example, 45 Hz, preferably 30 Hz, more preferably 25 Hz, and even more preferably Pulse wave signals SM1, SM2, and SM3 are extracted by performing low-pass filter processing each having an upper limit cutoff frequency (-3 dB cutoff frequency) that removes frequency components of 20 Hz or higher. These pulse wave signals SM1, SM2, and SM3 are sequentially stored in a predetermined storage area such as the RAM 74. Pulse wave signals SM1, SM2, and SM3 are shown in FIGS. 7 to 11, for example, and represent an upstream pulse wave, an intermediate pulse wave, and a downstream pulse wave, respectively.

The first-order differential waveform calculation unit 86 performs well-known first-order differential processing on the pulse wave signals SM1, SM2, and SM3 to form first-order differential waveforms dSM1/dt, dSM2/ Calculate dt and dSM3/dt, respectively. 7 to 11 show pressure vibrations superimposed on the compression pressure PC1 of the upstream inflation bag 22, the compression pressure PC2 of the intermediate inflation bag 24, and the compression pressure PC3 of the downstream inflation bag 26, using the pulse wave extraction unit 84. The waveforms of the pulse wave signals SM1, SM2, and SM3 extracted respectively and the first-order differential waveforms dSM1/dt, dSM2/dt, and dSM3/dt of the pulse wave signals SM1, SM2, and SM3 are combined, for example, with multiple step pressures P1, It is a diagram illustrating each of P2, P3, . . . Px.

FIG. 7 shows a state in which the compression pressure PC of the compression band 12 is higher than the systolic blood pressure value SBP of the living body, and the artery 18 of the upper arm 16 is closed with the upstream inflation bag 22, intermediate inflation bag 24, and downstream inflation bag 26. It shows. In this state, pressure fluctuations within the artery 18 cause only changes in the volume of the upstream inflation bag 22, while volume changes in the intermediate inflation bag 24 and the downstream inflation bag 26 are small, and the amplitude of the pulse wave signal SM1 changes. wave signals SM2 and SM3. The pulse wave signals SM2 and SM3 exhibit smaller amplitudes based on small volume changes (crosstalk) that are sequentially transmitted from the upstream inflation bag 22 to the intermediate inflation bladder 24 and the downstream inflation bladder 26.

FIG. 8 shows the state after the compression pressure PC of the compression band 12 becomes lower than the systolic blood pressure value SBP of the living body and blood flow starts. In this state, the blood flow causes changes in the volumes of the upstream inflation bag 22, intermediate inflation bag 24, and downstream inflation bag 26, and the pulse wave signal SM1, the amplitude of the intermediate inflation bag 24, and the downstream inflation bag 26 change. are similar to each other. In this state, first-order differential waveforms dSM1/dt, dSM2/dt, and dSM3/dt include first-order peak waves P1 _SM1 , P1 SM2 , and P1 SM3 corresponding to the rising slopes of pulse wave signals SM1, _SM2 , and _SM3 . Therefore, secondary peak waves P2 _SM1 , P2 _SM2 , and P2 _SM3 as shown in FIG. 9 are not formed. In the artery 18, when the blood flow reaches just below the downstream end 26c of the downstream inflation bag 26 shown in FIG. 1, the artery 18 directly below the upstream inflation bag 22 and the intermediate inflation bag 24 is closed. It is presumed that this is because the reflected waves generated directly below the downstream end 26c of the downstream expansion bag 26 do not reach there. Here, the peak wave indicates one independent peak-like waveform having one apex.

FIG. 9 shows a state in which the compression pressure PC of the compression band 12 is lower than that in FIG. 8. In this state, the primary differential waveforms dSM1/dt, dSM2/dt, and dSM3/dt include primary peak waves P1 SM1 , P1 SM2 , P1 SM3 corresponding to the rising slopes of the pulse wave signals _SM1 , _SM2 , and _SM3 , and Subsequent secondary peak waves P2 _SM1 , P2 _SM2 , and P2 _SM3 are formed, respectively. The secondary peak wave P2 _SM3 is superimposed on P1 _SM3 and cannot be recognized. The secondary peak waves P2 _SM1 , P2 _SM2 , and P2 _SM3 indicate the arrival of reflected waves generated just below the downstream end 26 c of the downstream expansion bag 26 . The reflected wave is generated at a point where the flow resistance (impedance) of blood flow suddenly changes within the artery 18, that is, at a point where the cross-sectional area of the artery 18 suddenly increases immediately below the downstream end 26c of the downstream inflation bag 26. This sudden increase in the cross-sectional area of the artery 18 is said to be a cause of so-called Korotkoff sounds.

FIG. 10 shows a state in which the compression pressure PC of the compression band 12 has become even lower than the state shown in FIG. 9 and has reached the diastolic blood pressure value DBP of the living body 14. In this state, in the first-order differential waveforms dSM1/dt, dSM2/dt, and dSM3/dt, the second-order peak waves P2 _SM1 , P2 _SM2 , and P2 _SM3 have almost disappeared, and as shown in A1 in FIG. In the first-order differential waveform dSM2/dt of the pulse wave signal SM2 extracted from the compression pressure PC2 in the expansion bag 24, not even a trace of the secondary peak wave P2 _SM2 is found. At the compression pressure PC that has reached such a diastolic blood pressure value DBP, it is estimated that almost no reflected waves are generated because the change in the cross-sectional area of the artery 18 is small just below the downstream end 26c of the downstream inflation bag 26.

FIG. 11 shows a state in which the compression pressure PC of the compression band 12 has become even lower than the state shown in FIG. 10, and has fallen below the diastolic blood pressure value DBP of the living body 14. In this state, since no reflected waves are generated, the secondary peak waves P2 SM1 , P2 _SM2 , and _{P2 SM3} completely disappear in the first-order differential waveforms dSM1/dt, dSM2/dt, and dSM3/dt.

The systolic blood pressure value determination unit 88 determines the systolic blood pressure value SBP using, for example, a well-known oscillometric blood pressure value determination algorithm. That is, for example, an envelope connecting the amplitude values of the pulse wave signal SM2 in the two-dimensional coordinates of the axis indicating the compression pressure PC of the compression band 12 and the axis indicating the pulse wave amplitude is generated, and the envelope of the envelope is The compression pressure PC of the compression band 12 that corresponds to a sudden increase, that is, the maximum point of the differential waveform of the envelope, is determined as the systolic blood pressure value SBP.

The diastolic blood pressure value determining unit 90 determines the downstream end of the downstream inflation bag 26 in the process of lowering the compression pressure PC of the compression cuff 12 from a preset boost target pressure value PCM that is sufficiently higher than the systolic blood pressure value SBP. Based on the compression pressure PC of the compression band 12 when the reflected wave that is reflected upstream from the point where the cross-sectional area of the artery 18 changes just below the portion 26c and is superimposed on the pulse wave signal SM2 is attenuated to less than a predetermined value, 14 diastolic blood pressure value DBP is determined. The diastolic blood pressure value determination unit 90 calculates, for example, the first derivative of the pulse wave signal SM2 in the process of lowering the compression pressure PC of the compression cuff 12 from a preset boost target pressure value PCM that is sufficiently higher than the systolic blood pressure value SBP. Compression when the secondary peak wave P2 _SM2 of the waveform dSM2/dt disappears, specifically when the magnitude (amplitude) of the secondary peak wave P2 _SM2 becomes less than the determination threshold Tdia1 set experimentally in advance. Based on the compression pressure PC of the band 12, the diastolic blood pressure value DBP of the living body 14 is determined.

FIG. 12 is a flowchart illustrating the main part of the control operation of the electronic control device 70. When the blood pressure measurement start operation button 80 is operated, the compression pressure PC of the compression cuff 12 is increased in step S1 (hereinafter, "step" is omitted) corresponding to the cuff pressure control section 82. Specifically, as shown in FIG. 6, the quick exhaust valve 52 is closed, the air pump 50 is activated, and the compressed air pumped from the air pump 50 pumps the inside of the main pipe 56 and the air. The pressure within the upstream inflation bladder 22, intermediate inflation bladder 24, and downstream inflation bladder 26, which are communicated with each other, is rapidly increased. Then, compression of the upper arm 16 by the compression band 12 is started.

Next, in S2 corresponding to the cuff pressure control unit 82, based on the output signal of the fourth pressure sensor T4 indicating the compression pressure PC of the compression cuff 12, the compression pressure PC is set to a preset boost target pressure value PCM (e.g. 180 mmHg) or more is determined. At a time point before time t2 in FIG. 6, the determination in S2 is negative, and steps S1 and subsequent steps in FIG. 12 are repeatedly executed.

When the compression pressure PC reaches the boost target pressure value PCM and the determination in S2 is affirmed, in S3 corresponding to the cuff pressure control section 82, the operation of the air pump 50 is stopped, and the upstream inflation bag 22 and the compression band The exhaust control valve 54 is configured to gradually exhaust the 12 compression pressures PC by step pressure reduction in which step pressures P1, P2, P3, . . . The first on-off valve E1, the second on-off valve E2, and the third on-off valve E3 are operated.

When maintaining the step pressures P1, P2, P3, . . . Px, the first on-off valve E1, the second on-off valve E2, and the third on-off valve E3 are each closed. Time t2 in FIG. 6 is the start point of the slow evacuation, and time t3 to t4 is the time during which the compression pressure PC of the compression cuff 12 is maintained at the step pressure P1 for a predetermined period of time, for example, while two beats occur. It is.

Next, in S4 corresponding to the pulse wave extraction section 84, the outputs from the first pressure sensor T1, the second pressure sensor T2, and the third pressure sensor T3 are output while the compression pressures PC1, PC2, and PC3 are each held for a predetermined time. Pulse waves representing pulse waves from the upstream expansion bag 22, intermediate expansion bag 24, and downstream expansion bag 26 are generated by performing low-pass filter processing on the signals to discriminate signals in a wavelength band of less than 25 Hz, respectively. The signals SM1, SM2, and SM3 are extracted, and the output signal from the fourth pressure sensor T4 is subjected to low-pass filter processing to extract the compression pressure PC of the compression band 12 from which the alternating current component has been removed. . Then, they are stored in association with each other.

In S5 corresponding to the cuff pressure control section 82, it is determined whether the compression pressure PC is equal to or less than a preset measurement end pressure value PCE (for example, 30 mmHg). At a time point before time t11 in FIG. 6, the determination in S5 is negative, and S3 and subsequent steps are repeatedly executed.

When the compression pressure PC becomes equal to or less than the measurement end pressure value PCE and the determination in S5 is affirmed, in S6 corresponding to the cuff pressure control section 82, the upstream inflation bag 22, the intermediate inflation bag 24, and the downstream inflation bag 26 are The quick exhaust valves 52 are operated so that the pressures of the respective pressures are exhausted to atmospheric pressure. This state is shown after time t11 in FIG.

Next, in S7 corresponding to the first-order differential waveform calculating section 86, first-order differential waveforms dSM1/dt, dSM2/dt, and dSM3/dt of the pulse wave signals SM1, SM2, and SM3 are calculated.

Next, in S8 corresponding to the first-order differential waveform calculating section, first-order peak waves P1 SM1 , corresponding to the rising slopes of the pulse wave signals SM1, SM2, and SM3 are calculated in the first-order differential waveforms dSM1/dt, dSM2/dt, and _dSM3 /dt. The magnitudes (amplitudes) of secondary peak waves P2 _SM1 , P2 _SM2 , and P2 _SM3 that occur following P1 _SM2 and P1 _SM3 are calculated.

Next, in S9 corresponding to the diastolic blood pressure value determination unit 90, in the process of lowering the compression pressure PC of the compression cuff 12 from the preset boost target pressure value PCM which is sufficiently higher than the systolic blood pressure value SBP, the pulse wave It is determined whether the magnitude (amplitude) of the secondary peak wave P2 of the first-order differential waveform dSM2/dt of the signal SM2 (intermediate pulse wave) _SM2 has fallen below the determination threshold Tdia1 set in advance to determine its extinction. be done. If the determination is negative, steps S7 and subsequent steps are repeatedly executed, but if the determination is affirmative, in S10 corresponding to the diastolic blood pressure value determination unit 90, based on the compression pressure PC of the compression band 12 at the time of the determination, Accordingly, the diastolic blood pressure value DBP of the living body 14 is determined. The reflected wave superimposed on the pulse wave signal SM2 (intermediate pulse wave) is difficult to recognize from the pulse wave signal SM2, and the existence of the reflected wave is determined by the secondary peak wave P2 of the first derivative waveform dSM2/dt and the magnitude (amplitude) of _SM2 . It is indicated by. Therefore, the determination as to whether or not the magnitude (amplitude) of the secondary peak wave P2 _SM2 has fallen below the determination threshold Tdia1 set in advance to determine its extinction is the determination of the presence or absence of attenuation of the reflected wave. ing.

Then, in S11 corresponding to the systolic blood pressure value determination unit 88, an envelope is generated that connects the amplitude values of the pulse wave signal SM2 in the two-dimensional coordinates of the axis indicating the compression pressure PC and the axis indicating the pulse wave amplitude. , when the envelope of the compression band 12 suddenly increases in the process of being lowered from the preset boost target pressure value PCM which is sufficiently higher than the systolic blood pressure value SBP, that is, the differential waveform of the envelope. The compression pressure PC of the compression band 12 corresponding to the maximum point of is determined as the systolic blood pressure value SBP. The systolic blood pressure value SBP determined in S11 and the diastolic blood pressure value DBP determined in S10 are displayed on the display device 78.

As described above, according to the automatic blood pressure measuring device 10 of the present embodiment, in the process of changing the compression pressure PC on the compressed site 16 by the compression band 12, the living body 14 contained in the compression pressure PC2 in the intermediate inflation bag 24 a pulse wave extraction unit 84 that extracts an intermediate pulse wave (pulse wave signal SM2) that is a pressure oscillation synchronized with the heartbeat of In the process of being lowered from the downstream end 26c of the downstream inflation bag 26, it is reflected upstream from the point where the cross-sectional area of the artery (arterial blood vessel) 18 changes and becomes an intermediate pulse wave (pulse wave signal SM2). It includes a diastolic blood pressure value determination unit 90 that determines the diastolic blood pressure value DBP of the living body 14 based on the compression pressure PC of the compression cuff 12 when the magnitude of the superimposed reflected wave attenuates below a predetermined value. As a result, as the compression pressure PC changes, the diastolic blood pressure value DBP of the living body 14 can be stably determined based on the attenuation of the reflected wave superimposed on the intermediate pulse wave (pulse wave signal SM2) near the diastolic blood pressure value DBP. The decision accuracy is improved.

Further, according to the automatic blood pressure measurement device 10 of the present embodiment, the diastolic blood pressure value determining unit 90 causes the compression pressure PC of the compression cuff 12 to decrease from the boost target pressure value PCM which is sufficiently higher than the systolic blood pressure value SBP of the living body 14. In the process, the compression pressure PC of the compression band 12 when the secondary peak wave P2 _SM2 of the first differential waveform dSM2/dt of the intermediate pulse wave (pulse wave signal SM2) becomes less than the preset determination threshold Tdia1. Based on this, the diastolic blood pressure value DBP of the living body 14 is determined. In this way, since the secondary peak wave P2 _SM2 of the first differential waveform dSM2/dt of the intermediate pulse wave (pulse wave signal SM2) has become less than the determination threshold Tdia1, the It is stably determined that the reflected wave reflected upstream from the point where the cross-sectional area of the artery 18 changes and is superimposed on the intermediate pulse wave (pulse wave signal SM2) has attenuated to less than a predetermined value. The accuracy of determining the diastolic blood pressure value DBP is improved.

Further, according to the automatic blood pressure measuring device 10 of the present embodiment, the pulse wave extraction unit 84 converts the signal representing the compression pressure PC2 in the intermediate inflation bag 24 into an upper limit cutoff frequency that removes frequency components of at least 45 Hz or more. By performing a low-pass filter process having the following, an intermediate pulse wave (pulse wave signal SM2), which is a pressure vibration included in the compression pressure PC2 in the intermediate inflation bag 24, is extracted. As a result, an intermediate pulse wave (pulse wave signal SM2) that clearly includes features indicating the influence of reflected waves is obtained, so that the accuracy of determining the diastolic blood pressure value DBP of the living body 14 is improved.

Next, other embodiments of the present invention will be described. In the following description of the embodiments, parts that overlap with each other in the embodiments will be designated by the same reference numerals and the description thereof will be omitted.

FIG. 13 is a functional block diagram illustrating the functions of another embodiment of the electronic control device 70. The electronic control device 70 shown in FIG. 13 is different from the electronic control device 70 shown in FIG. , differ. The second-order differential waveform calculation unit 92 performs well-known second-order differential processing on the pulse wave signals SM1, SM2, and SM3 to calculate the second-order differential waveforms d ² SM1/ of the pulse wave signals SM1, SM2, and SM3. dt ² , d ² SM2/dt ² and d ² SM3/dt ² are calculated, respectively. Further, the second-order differential waveform calculation unit 92 calculates a waveform Δdw for a predetermined period, which is a portion of the second-order differential waveform d ² SM2/dt ² of the intermediate pulse wave _SM2 following the first maximum minimum wave W1 SM2. 14 to 18 show the pressure vibrations superimposed on the compression pressure PC1 of the upstream inflation bag 22, the compression pressure PC2 of the intermediate inflation bag 24, and the compression pressure PC3 of the downstream inflation bag 26, using the pulse wave extraction unit 84. The waveforms of the pulse wave signals SM1, SM2, and SM3 extracted respectively, and the second-order differential waveforms d ² SM1/dt ² , d ² SM2/dt ² , and d ² SM3/dt ² of the pulse wave signals SM1, SM2, and SM3. 2 is a diagram illustrating, for example, each step pressure P1, P2, P3, . . . Px in multiple stages.

FIG. 14 shows a state in which the compression pressure PC of the compression band 12 is higher than the systolic blood pressure value SBP of the living body, and the artery 18 of the upper arm 16 is closed with the upstream inflation bag 22, intermediate inflation bag 24, and downstream inflation bag 26. It shows. In this state, pressure fluctuations within the artery 18 cause only changes in the volume of the upstream inflation bag 22, while volume changes in the intermediate inflation bag 24 and the downstream inflation bag 26 are small, and the amplitude of the pulse wave signal SM1 changes. wave signals SM2 and SM3. The pulse wave signals SM2 and SM3 exhibit smaller amplitudes based on small volume changes (crosstalk) that are sequentially transmitted from the upstream inflation bag 22 to the intermediate inflation bladder 24 and the downstream inflation bladder 26.

FIG. 15 shows the state after the compression pressure PC of the compression band 12 becomes lower than the systolic blood pressure value of the living body and blood flow starts. In this state, the blood flow causes changes in the volumes of the upstream inflation bag 22, intermediate inflation bag 24, and downstream inflation bag 26, and the pulse wave signal SM1, the amplitude of the intermediate inflation bag 24, and the downstream inflation bag 26 change. are similar to each other. In this state, the second-order differential waveforms d ² SM1/dt ² , d ² SM2/dt ² and d ² SM3/dt ² are the first-order differential waveforms dSM1/dt, dSM2/dt and dSM3/dt, which respectively show the slopes. Maximum and minimum waves W1 _SM1 , W1 _SM2 , and W1 _SM3 are shown, and they each intersect in the vertical direction with respect to the baseline (zero line) ZL indicating zero. When the blood flow reaches the downstream end 26c of the downstream inflation bag 26 in the artery 18, the artery 18 directly below the upstream inflation bag 22 and the intermediate inflation bag 24 is closed, and the downstream inflation bag 26 Since the reflected waves generated directly below the downstream end portion 26c do not reach the downstream end portion 26c, the influence of the reflected waves is not observed. Here, the maximum and minimum wave refers to a waveform of one period including a peak having one maximum point and a trough having one minimum point.

FIG. 16 shows a state in which the compression pressure PC of the compression band 12 is lower than that in FIG. 15. In this state, the second-order differential waveforms d ² SM1/dt ² , d ² SM2/dt ² and d ² SM3/dt ² have the first-order peaks of the above-mentioned first-order differential waveforms dSM1/dt, dSM2/dt and dSM3/dt. Corresponding to the waves P1 _SM1 , P1 _SM2 , P1 _SM3 and the subsequent secondary peak waves P2 _SM1 , P2 SM2 , _{P2 SM3} , the primary maximum and minimum waves W1 _SM1 , W1 _SM2 , W1 _SM3 and the secondary maximum and minimum waves W2 _SM1 , W2 _SM2 , and W2 _SM3 are formed, respectively. These secondary maximum and minimum waves W2 _SM1 , W2 _SM2 , and W2 _SM3 intersect the base line (zero line) ZL in the vertical direction, respectively.

FIG. 17 shows a state in which the compression pressure PC of the compression band 12 has become even lower than the state shown in FIG. 16 and has reached the diastolic blood pressure value DBP of the living body 14. In this state, the second-order differential waveforms d ² SM1/dt ² , d ² SM2/dt ² and d ² SM3/dt ² include the second-order peaks of the first-order differential waveforms dSM1/dt, dSM2/dt and dSM3/dt described above. Secondary maximum and minimum waves W2 _SM1 , W2 _SM2 and W2 _SM3 corresponding to waves P2 _SM1 , P2 _SM2 and P2 _SM3 are suppressed. In particular, in the second-order differential waveform d ² SM2/dt ² , as shown in B1 of FIG. 17, since there is no second-order maximum and minimum wave W2 _SM2 corresponding to the second-order peak wave P2 _SM2 , the second-order differential waveform d ² SM2 /dt ² excluding the primary maximum and minimum waves W1 _SM2 , that is, the waveform Δdw for a predetermined period after the primary maximum and minimum waves W1 _{and SM2} does not intersect the baseline (zero line) ZL. This is because, as shown in A1 of FIG. 10, no trace of the secondary peak wave P2 _SM2 is found in the first-order differential waveform dSM2/dt. At the compression pressure PC that has reached such a diastolic blood pressure value DBP, it is estimated that almost no reflected waves are generated because the change in the cross-sectional area of the artery 18 is small below the downstream end 26c of the downstream inflation bag 26.

FIG. 18 shows a state in which the compression pressure PC of the compression band 12 has become even lower than the state shown in FIG. 17, and has fallen below the diastolic blood pressure value DBP of the living body 14. In this state, since no reflected waves occur, the first-order differential waveforms ^dSM1 / ^dt , ^dSM2 / ^{dt and dSM3} / The secondary maximum and minimum waves W2 _SM1 , W2 _SM2 , W2 _SM3 corresponding to the secondary peak waves P2 _SM1 , P2 _SM2 , P2 _SM3 of dt have completely disappeared.

The diastolic blood pressure value determination unit 94 determines the downstream end of the downstream inflation bag 26 in the process of lowering the compression pressure PC of the compression cuff 12 from a preset elevated target pressure value PCM that is sufficiently higher than the systolic blood pressure value SBP. The compression pressure PC of the compression band 12 when the reflected wave that is reflected upstream from the point where the cross-sectional area of the artery 18 changes under the section 26c and is superimposed on the intermediate pulse wave (pulse wave signal SM2) is attenuated to less than a predetermined value. Based on this, the diastolic blood pressure value DBP of the living body 14 is determined. That is, the diastolic blood pressure value determination unit 94 determines, for example, the intermediate pulse wave SM2 (pulse wave signal SM2 ) The compression pressure PC of the compression band 12 when the waveform _{Δdw for a predetermined period, which is the part following SM2} ^{, no} longer intersects the base line (zero line) ZL. Based on this, the diastolic blood pressure value DBP of the living body 14 is determined.

FIG. 19 is a flowchart illustrating another example of the operation of the electronic control device 70. In FIG. 19, S1 to S6 and S11 are the same as those in FIG. 12, so their explanation will be omitted. In FIG. 19, S7 to S10 in FIG. 12 are replaced with S17 to S20.

In S17 corresponding to the second-order differential waveform calculation unit 92, second-order differential waveforms d ² SM1/dt ² , d ² SM2/dt ² and d ² SM3/dt ² of the pulse wave signals SM1, SM2 and SM3 are calculated. be done. Next, in S18 corresponding to the second-order differential waveform calculation unit 92, the second-order differential waveform d ² SM2/dt ² is calculated as a waveform Δdw for a predetermined period excluding the portion after the first-order maximum and minimum waves W1 _{and SM2} , that is, the first-order maximum and minimum waves W1 _{and SM2} . is calculated.

Next, in S19 corresponding to the diastolic blood pressure value determination unit 94, in the process of lowering the compression pressure PC of the compression cuff 12 from the preset boost target pressure value PCM which is sufficiently higher than the systolic blood pressure value SBP, a secondary Differential waveform d ² SM2/dt ² Primary maximum minimum wave W1 _SM2 The part after the primary maximum minimum wave W1 SM2, that is, the waveform Δdw for a predetermined period excluding the primary maximum minimum wave W1 _SM2 , is determined to be lower than the baseline (zero line) ZL. be judged. If the judgment in S19 is negative, the steps from S17 onward are repeatedly executed, but if the judgment is affirmative, in S20 corresponding to the diastolic blood pressure value determining section 94, the pressure band 12 is Based on the compression pressure PC, the diastolic blood pressure value DBP of the living body 14 is determined.

According to the automatic blood pressure measuring device 10 of the present embodiment, the diastolic blood pressure value determining unit 94 determines that the compression pressure PC by the compression cuff 12 is determined from the boost target pressure value PCM which is set sufficiently higher than the systolic blood pressure value SBP of the living body 14. In the process of being lowered, the second-order differential waveform d2 ^SM2 / ^dt of the intermediate pulse wave (pulse wave signal SM2), the first-order maximum minimum wave W1 of 2, and the waveform Δdw for a predetermined period after _SM2 intersects the baseline (zero line) ZL. The diastolic blood pressure value DBP of the living body 14 is determined based on the compression pressure PC of the compression band 12 when the compression band 12 stops. As a result, it is stable that the waveform Δdw of the second-order differential waveform d ² SM2/dt ² of the intermediate pulse wave (pulse wave signal SM2), the first-order maximum minimum wave W1, and the waveform Δdw for a predetermined period after _SM2 no longer intersects the baseline ZL. Therefore, the accuracy of determining the diastolic blood pressure value DBP of the living body 14 is improved.

Although one embodiment of the present invention has been described above in detail with reference to the drawings, the present invention is not limited to this embodiment and may be implemented in other forms.

For example, one of the diastolic blood pressure value DBP determined by the diastolic blood pressure value determination unit 90 of the first embodiment and the diastolic blood pressure value DBP determined by the diastolic blood pressure value determination unit 94 of the second embodiment is displayed on the display device 78. It may be displayed as a blood pressure value, or the average value of both may be displayed on the display device 78 as a diastolic blood pressure value.

In Examples 1 and 2, the compression pressure PC on the upper arm 16 by the compression band 12 is the compression pressure PC1 in the upstream inflation bag 22, the compression pressure PC2 in the intermediate inflation bag 24, and the compression pressure PC2 in the downstream inflation bag 26. The compression pressure PC3 or the average pressure thereof may be used.

In addition, in FIG. 12 of the first embodiment or FIG. 19 of the second embodiment, after S6 when the compression band 12 finishes compressing the upper arm 16, the first-order differential waveforms dSM1/dt, dSM2/dt, dSM3/dt and second-order differential waveforms dSM1/dt, dSM2/dt, dSM3/dt and Calculation of secondary peak wave P2 _SM2 , secondary differential waveform d ² SM1/dt ² , d ² SM2/dt ² , d ² SM3/dt ² and primary maximum and minimum wave W1 _SM2 in secondary differential waveform d ² SM2/dt ² The calculation process of the waveform Δdw for a later predetermined period was performed, but for example, these calculation processes were performed sequentially while the step pressures P1, P2, P3, . . . Px were being formed. Good too.

Further, in Examples 1 and 2, the compression band 12 presses the upper arm 16, but it may also press a part of the living body 14, such as a wrist or a lower limb.

Further, in Examples 1 and 2, step pressure reduction was employed as the compression method for measuring blood pressure using the compression cuff 12, but continuous pressure reduction or continuous pressure increase may be used.

Furthermore, in the first and second embodiments, the number of inflation bags provided in the compression band 12 is not limited to three, but may be four or more. It is sufficient that the upstream expansion bag 22, the downstream expansion bag 26, and the intermediate expansion bag 24 provided therebetween are relatively present.

The above-mentioned embodiment is merely one embodiment, and although no other examples are given, the present invention can be implemented with various changes and improvements based on the knowledge of those skilled in the art without departing from the spirit thereof. Can be done.

10: Automatic blood pressure measuring device 12: Compression band 14: Living body 16: Upper arm (compressed area)
22: Upstream expansion bag 24: Intermediate expansion bag 26: Downstream expansion bag 26c: Downstream end 84: Pulse wave extraction section 90, 94: Diastolic blood pressure value determination section 92: Second differential waveform calculation section SBP: Systolic blood pressure Value DBP: Diastolic blood pressure value dSM2/dt: First-order differential waveform ^d2 SM2/ ^dt2 : Second-order differential waveform PC: Compression pressure of compression cuff PC2: Compression pressure in intermediate inflation bag PCM: Boost target pressure value (systolic blood pressure value (value higher than)
P2 _SM2 : Secondary peak wave SM2: Pulse wave signal (intermediate pulse wave)
W1 _SM2 : Primary maximum minimum wave Δdw: Waveform for a predetermined period

Claims (3)

The upstream inflation bag has an independent upstream inflation bag, an intermediate inflation bag, and a downstream inflation bag that are wrapped around a compressed part of a living body and are connected in the width direction to compress the compressed part of the living body, respectively. , an automatic blood pressure measuring device comprising a compression band that compresses the arterial blood vessel in the compressed region with the same compression pressure by the intermediate expansion bag and the downstream expansion bag,
a pulse wave extraction unit that extracts an intermediate pulse wave that is a pressure vibration synchronized with the heartbeat of the living body contained in the compression pressure in the intermediate expansion bag in the process of changing the compression pressure on the compressed region by the compression band; ,
A reflection reflected toward the upstream side from a point where the cross-sectional area of the arterial blood vessel changes under the downstream end of the downstream inflation bag during the process in which the compression pressure of the compression band is lowered from a value higher than the systolic blood pressure value. The diastolic blood pressure of the living body is determined based on the compression pressure of the compression band when the magnitude or amplitude of the secondary peak wave of the first derivative waveform of the intermediate pulse wave on which the waves are superimposed is less than a preset determination threshold. An automatic blood pressure measuring device comprising: a diastolic blood pressure value determination unit that determines a diastolic blood pressure value. The upstream inflation bag has an independent upstream inflation bag, an intermediate inflation bag, and a downstream inflation bag that are wrapped around a compressed part of a living body and are connected in the width direction to compress the compressed part of the living body, respectively. , an automatic blood pressure measuring device comprising a compression band that compresses the arterial blood vessel in the compressed region with the same compression pressure by the intermediate expansion bag and the downstream expansion bag,
a pulse wave extraction unit that extracts an intermediate pulse wave that is a pressure vibration synchronized with the heartbeat of the living body contained in the compression pressure in the intermediate expansion bag in the process of changing the compression pressure on the compressed region by the compression band; ,
Reflected waves reflected toward the upstream side from a point where the cross-sectional area of the arterial blood vessel changes under the downstream end of the downstream inflation bag during the process in which the compression pressure of the compression band is lowered from a value higher than the systolic blood pressure value. The diastolic blood pressure of the living body is determined based on the compression pressure of the compression band when the waveform for a predetermined period after the first maximum minimum wave in the second-order differential waveform of the intermediate pulse wave superimposed on the waveform no longer intersects the baseline indicating zero. a diastolic blood pressure value determination unit that determines the value;
An automatic blood pressure measuring device characterized by: The pulse wave extraction unit performs low-pass filter processing on the signal representing the compression pressure in the intermediate inflation bag, which has an upper limit cutoff frequency that removes frequency components of 45 Hz or higher, thereby determining the compression pressure in the intermediate inflation bag. The automatic blood pressure measuring device according to claim 1 or 2, wherein the intermediate pulse wave that is included in the pressure vibration is extracted.

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