JP6340152B2 - Automatic blood pressure measurement device - Google Patents

Description

  The present invention relates to an automatic blood pressure measurement provided with a compression band wound around a compression site in order to detect a pulse wave generated from a peripheral artery in the compression site that is a part of a living body such as an arm or an ankle. It relates to the device.

  The living body circulatory system information such as the blood pressure value of the living body detects the pulse wave generated in synchronization with the pulsation from the artery of the living body as the pressure vibration in the compression band wound around the pressed portion of the living body, It is measured based on the compression pressure of the compression band when the magnitude of the pulse wave becomes a preset change state. Such indirect blood pressure measurement is known as an oscillometric method or a cuff vibration method. In such an oscillometric method, the magnitude of the cuff volume pulse wave, which is a pressure vibration generated in the cuff, is increased and decreased with a continuous change in the compression pressure of the compression band, and an envelope that connects the amplitude values of the cuff pulse wave ( The blood pressure value is statistically determined by comparing the amplitude ratio obtained by normalizing the cuff pulse wave amplitude with the maximum pulse amplitude value and the blood pressure measurement value obtained by the auscultation method. For example, this is the blood pressure measurement device shown in Patent Document 1.

  Also, conventionally, it is judged that the pulse oscillates maximum when the arterial pressure and the cuff pressure are balanced, and it appears in the pipe law in the relationship between the lumen cross-sectional area of the arterial blood vessel called the pipe law and the transmural pressure of the blood vessel. It has been considered that the pressure at which the compliance is maximum corresponds to the mean blood pressure of the arterial pressure. As a result, in the basic principle of the oscillometric method, it has been assumed that the cuff pressure indicating the maximum amplitude of the envelope corresponds to the average blood pressure based on this tube law.

Japanese Patent Application Laid-Open No. 07-236617

  However, the blood pressure measurement value obtained by the conventional oscillometric method is estimated (calculated) from the statistical relationship obtained in advance, and is based on the maximum value of the pulse wave envelope that is affected by the cuff blood pressure measurement method. There is a problem that the accuracy cannot be obtained sufficiently.

  An object of the present invention is to provide an automatic blood pressure measurement device that can obtain high measurement accuracy for blood pressure values.

  When the cuff pressure exceeds the minimum blood pressure value of the arterial pressure, the inventor starts to applanate easily. As shown in FIG. 21, the cuff pressure at which the compliance with the above-mentioned pipe rule is maximum is the minimum blood pressure value of the arterial pressure. I found it nearby. Conventionally, the nonlinear characteristics of the above-mentioned tube law of the blood vessel wall seen in the aortic system, and the elastic tube properties rich in elastic fibers that maintain the circular tube even when the intravascular pressure decreases and the transmural pressure becomes negative, When applied to the peripheral brachial artery, it has been considered that the pressure that is the maximum compliance of the tube law corresponds to the mean blood pressure. The reason for this was that the brachial blood pressure measurement method using the armband affected the peripheral blood circulation state downstream of the armband attachment site. That is, in the process of blood pressure measurement by the cuff method, the peripheral arterial pressure rises corresponding to the blood flow flowing into the peripheral arterial system from the cuff, and the blood vessel under the cuff always opens when the cuff pressure is exceeded. As a result of the decrease in the amplitude of the cuff volume pulse wave, the maximum value of the envelope is formed in the vicinity of the pressure assumed to be the average blood pressure value. A transmural pressure higher than the maximum point of vascular compliance shown in FIG. 21 shows a characteristic that the vascular compliance decreases due to an increase in vascular wall elasticity. A transmural pressure lower than the maximum point of vascular compliance is affected by the blood pressure measurement conditions. However, as the blood vessel compliance decreases and the cuff pressure becomes higher than the minimum blood pressure, it is determined that the blood vessel becomes inflated. As described above, the cuff pressure at which the cuff volume pulse wave has the maximum amplitude depends on the blood pressure measurement method and the circulation state of the living body at the time of measurement, and is not constant. In addition, in the blood pressure measurement by the cuff method as described above, the arterial pressure (hydrostatic pressure) increases according to the blood flow state of the artery on the peripheral side from the cuff at the time of measurement. The reflected wave is superimposed near the top of the systole of the cuff volume pulse wave from the maximum blood pressure value to the vicinity of the minimum blood pressure value. This transient reflected wave increases the amplitude of the cuff volume pulse wave. Therefore, using the conventional oscillometric method, the vicinity of the inflection point of the envelope (envelope) connecting the amplitude values of the cuff pulse wave, or the amplitude ratio obtained by normalizing the cuff pulse wave amplitude with the maximum pulse amplitude value, The blood pressure value estimated (measured) to match the blood pressure value obtained by the auscultation method is based on the pulse wave envelope that is affected by the cuff blood pressure measurement method, which does not provide sufficient blood pressure measurement accuracy. It was thought to be the cause.

The present inventor has conducted various studies against the background described above, and as a result, the transmural pressure Pt (= minimum blood pressure value DBP−compression pressure Pcuff of the compression band) [mmHg] and the cross-sectional area of the arterial blood vessel. For example, in the PA curve shown in FIG. 21 representing the relationship between A [cm ² ], the pressure pulse wave that is an input to the arterial blood vessel and the volume pulse wave amplitude that is the output from the arterial blood vessel (cuff pulse) When the relationship with the wave amplitude is determined and considered, in the portion of the PA curve where the cross-sectional area A is close to zero, the transmural pressure Pt is negative, and blood stays on the peripheral side from the cuff compression site. It is presumed that the peripheral arterial pressure (hydrostatic pressure) is increased. On the PA curve, the vicinity of zero of the transmural pressure Pt is the maximum slope of the PA curve, and the arterial blood vessel The maximum compliance part of the arteries Since it is a part that is easily deformed, as shown in FIG. 22, the point that the volume pulse wave with the maximum amplitude is output with respect to the input (pressure wave) of the same magnitude, and the pulse pressure as shown in FIG. Volume pulse wave amplitude that changes with changes in compression pressure Pcuff in the compression zone, with PP (intraductal pressure amplitude of 1 beat = maximum blood pressure value of 1 beat−minimum blood pressure value) [mmHg] as a parameter (parameter) As the pulse pressure PP becomes smaller, the shape of each envelope becomes closer to the compliance curve, and the maximum amplitude point of the envelope can be determined with high accuracy, so that it approaches the previously measured minimum blood pressure value (diastolic blood pressure) DBP. Pay attention. The present inventor has found that the reason why the amplitude of the cuff volume pulse wave decreases from the maximum amplitude in the process of decreasing the cuff pressure is that the propagation velocity formed across the steeply inclined portion near the minimum blood pressure value of the PA curve. Assuming the theory that a pressure pulse wave including a slow component (a gentle shape portion of a pulse wave) and a fast component (a sharp shape portion of a pulse wave) generates Korotkoff sounds, P- A steep slope in the vicinity of the minimum blood pressure value on the A curve, that is, a component of a slow pressure pulse wave that has passed the maximum portion of the vascular compliance toward the low-pressure side is the main component, and the disappearance wave of the Korotkoff sound (Korotkoff corresponding to the minimum blood pressure) Swan fifth point of sound), therefore, the minimum blood pressure value by the oscillometric method that statistically determines the minimum blood pressure value based on the amplitude decrease of the cuff volume pulse wave whose amplitude is determined solely by the fast component Blood It was presumed to deviate from the measured diastolic blood pressure value using. The inventor has found that the non-linearity of vascular compliance is detected more accurately as the pulse wave amplitude is smaller, and the pressure pulse wave is a systole formed depending on the amount of blood pumped out during the systole of the heart. Propagated arterial system as a composite wave formed from diastolic pulse wave caused by aortic system that circulates blood stored in systole to peripheral due to pulse wave and aortic system compliance. A method of separating the systolic pulse wave, which is the main component of the wave amplitude, from the diastolic pulse wave, which is the secondary component, was devised, and the relatively small diastole that occurs in the diastole below the notch pressure of the pulse wave It was estimated that the accuracy of the minimum blood pressure value of the living body could be improved by measuring the minimum blood pressure value of the living body using the diastolic time phase wave generated in the phase separated from the pressure pulse wave. When the cuff pressure is higher than the end-systolic pressure of the pressure pulse wave, only the systolic time phase wave consisting of the systolic pulse wave of the living body and the attenuation component of the systolic pulse wave appears in the cuff pulse wave . The attenuation time constant of the attenuation component is attenuated to the level of the diastolic blood pressure at the steady state of the average pulse wave cycle, and can be approximated without depending on the pulse wave amplitude. When the cuff pressure is lower than the end-systolic pressure, the hydrostatic pressure rises transiently depending on the diastolic wave and the amount of blood staying (congested) in the cuff downstream due to the presence of the cuff and cuff pressure during blood pressure measurement. As a phenomenon, the reflected wave may be superimposed on the systole time phase of the pulse wave. The main component of the reflected wave from the peripheral side of the transient cuff appears in the systole, and the cuff pressure is superimposed on the mid-systolic waveform immediately after the end systolic pressure, and the first half of the systole with a decrease in the cuff pressure. When the superimposition start point shifts to and the cuff pressure is reduced below the minimum blood pressure, it gradually disappears and returns to a steady state. The diastolic wave and the transient reflected wave appear as the cuff pressure decreases, but generally the diastolic wave appears first. When the peripheral vascular resistance is small, such as a young person, the end systolic pressure is decreased and a reflected wave may appear first. In this case, the reflected wave is delayed, and the influence of the reflected wave on the volume pulse wave amplitude is small.
Therefore, the present inventor detects the systolic time phase wave, subtracts the systolic time phase wave from the cuff volume pulse wave including the diastole wave appearing at a cuff pressure lower than the end systolic pressure, By extracting the diastolic wave in the interval, when the minimum blood pressure value of the living body is determined based on the amplitude of the diastolic volume pulse wave, which is a fraction of the amplitude of the cuff volume pulse wave, The diastolic blood pressure value by the cuff oscillometric method was obtained with high accuracy. The present invention has been made based on such knowledge.

That is, the automatic blood pressure measurement device of the present invention includes (a) a compression band that is wound around a part of a living body and reduces the compression pressure on the part of the living body, and in the process of reducing the compression pressure of the compression band. An automatic blood pressure measurement device that measures a minimum blood pressure value of the living body based on a cuff volume pulse wave that is an alternating current component synchronized with the pulse of the living body, included in the obtained cuff pressure signal representing the compression pressure, (B) Among the cuff volume pulse waves, the end-systolic pressure pulse volume pulse that is a cuff volume pulse when the cuff pressure is the end-systolic pressure of the living body or one volume pulse wave connected thereto is used as a reference wave. The reference value so that the cuff volume pulse wave sequentially obtained when the cuff pressure is equal to or lower than the end-systolic pressure of the living body is equal to the amplitude of the superimposed start point of the reflected wave included in the cuff volume pulse wave. Shrinkage that generates systolic time phase waves with adjusted waves A time phase wave generating unit; and (c) subtracting the waveform of the generated systolic time phase wave from the waveform of each cuff volume pulse wave sequentially obtained when the cuff pressure is equal to or lower than the end-systolic pressure of the living body. A diastolic synthesized wave generating unit for generating diastolic synthesized waves each composed of a diastolic wave and a reflected wave, and (d) determining the minimum blood pressure value of the living body based on the amplitude of the generated diastolic synthesized wave And a diastolic blood pressure value determining unit.

  According to the automatic blood pressure measurement device configured as described above, the diastolic component wave included in the cuff volume pulse wave is extracted by subtracting the systolic time phase wave from the cuff volume pulse wave, and Since the diastolic blood pressure value of the living body is calculated based on the amplitude, the diastolic blood pressure value is determined by a small pulse of about a fraction that is not affected by the systolic time phase wave included in the cuff volume pulse wave. Since the pressure component is used, high measurement accuracy can be obtained for the minimum blood pressure value.

Here, preferably, for example, a DC component that is a compression pressure from the cuff pressure signal to the part of the living body field by performing a low-pass filter process that performs a moving average process at intervals of an average period of a pulse wave during blood pressure measurement. extracting, and the cuff pressure signal and the cuff volumetric pulse wave generator generating the mosquito mutabilis product pulse wave by obtaining the difference between the DC component, the mosquito mutabilis systolic wave Sekimyakuha to continue communicating And a systolic end-of-systolic end-of-systolic pressure determining unit that determines the cuff pressure when the negative minimum value of the first-order differential waveform generated corresponding to the inflection point of the descending leg is minimum as the end-systolic end-of-systolic pressure. In this way, the cuff volume pulse wave synchronized with the heartbeat of the living body and the end systolic pressure of the living body can be easily obtained.

  Preferably, the end systolic pressure determining unit determines the detection of the inflection point of the primary differential waveform of the cuff volume pulse wave on the common time axis based on the minimum point of the secondary differential waveform, The cuff pressure when the amplitude value of the cuff volume pulse wave corresponding to the negative minimum point of the second derivative waveform exceeds 50% of the maximum amplitude of the cuff volume pulse wave is determined as the end systolic pressure. In addition. In this way, the point where the reflected wave overlaps the systolic time phase wave ahead of the diastole wave and the negative minimum of the first derivative waveform of the early cuff volume pulse wave is minimized is the diastole time phase. Even when it is extended, the end systolic pressure is accurately determined. When the cuff pressure at the time when the negative minimum point of the first derivative waveform of the cuff volume pulse wave is minimized is determined as the end systolic pressure, the negative minimum point is broadened due to the superposition of the reflected wave and is not effective. The accuracy of end-systolic pressure may not be obtained due to clarification or multiple occurrences.

Preferably, the systolic time phase wave generation unit is configured to change from the positive to the negative of the second derivative wave from the rising leg to the top of the cuff volume pulse wave obtained at a cuff pressure lower than the end systolic pressure. A reflected wave superposition start point determination unit that determines the inflection point of the cuff volume pulse wave as a reflected wave superposition start point corresponding to the minimum point of the first-order differential wave at the zero crossing point, and lower than the end systolic pressure The cuff volume pulse wave obtained by cuff pressure and the reference wave are delayed from the maximum amplitude time of the reference wave of the systolic time phase wave when their rising start points coincide on the common time axis If there is a reflected wave superposition start point, the maximum amplitude value of the reference wave is A _ESBP , the cuff volume pulse wave amplitude at that time is A _PVR , and the reflected wave superposition start point of the previous period is from the maximum amplitude time of the reference wave If present in the previous pulse wave leg, its cuff volume The amplitude and _{A PVR} in the reflected wave overlap starting point of the wave, the amplitude value of the reflected wave overlap starting point of the reference wave as the _{A ESBP,} Searching for the amplitude ratio _{A ratio (= A PVR / A} ESBP), A reference wave correction unit that generates the systolic time phase wave by multiplying the reference wave by the amplitude ratio A _ratio . In this way, it is possible to easily obtain systolic time phase waves respectively included in the cuff volume pulse wave obtained at a cuff pressure lower than the end systolic pressure.

  Preferably, the diastolic synthetic wave generation unit is configured so that, on the common time axis, the amplitude of the cuff volume pulse wave sequentially obtained when the cuff pressure is equal to or lower than the end-systolic pressure of the living body, By subtracting the amplitude of the systolic time phase wave generated for each diastolic phase, each diastolic synthesized wave is sequentially generated in the process of decreasing the cuff pressure. In this way, a plurality of diastolic synthesized waves can be easily obtained in time series.

Also, preferably, the diastolic blood pressure value determination section, the diastolic composite wave generation unit series of diastolic diastolic composite wave diastolic after one indicating the maximum amplitude of the composite wave generated by The cuff pressure corresponding to the composite wave is determined as the minimum blood pressure value. In this way, the correlation with the minimum blood pressure value obtained by the blood pressure measurement by the open method, that is, the direct method using a catheter, is further enhanced, and measurement accuracy without a tendency error can be obtained.

  Preferably, the cuff volume pulse wave sequentially obtained during the cuff pressure drop period and the volume pulse wave composed of the systolic time phase wave respectively included in the cuff volume pulse wave are lower than the end systolic pressure. The cuff pressure corresponding to the pulse wave whose amplitude ratio obtained by normalizing the amplitude of the systolic time phase wave with its maximum pulse amplitude value becomes a predetermined amplitude ratio near the inflection point of the envelope (envelope) connecting the amplitude values A systolic blood pressure value determining unit that determines the systolic blood pressure value is further included. In this way, since the systolic blood pressure value is determined using the systolic time phase component of the cuff volume pulse wave, the amplitude of the pulse waveform on which the reflected wave of the cuff volume pulse wave is superimposed increases, and a plurality of envelopes are added to the envelope. The accuracy of the systolic blood pressure value is improved as compared with the case of using the oscillometric method in which the systolic blood pressure value is determined under the situation where the inflection point appears or the reflected wave component is included in the maximum amplitude of the pulse waveform.

1 shows an automatic blood pressure measurement device according to an embodiment of the present invention, which includes an upper arm compression band that is wound around an upper arm that is a compressed portion of a living body. It is the figure which notched a part which shows the outer peripheral surface of the compression belt | band | zone of FIG. It is a top view which shows the upstream expansion bag, the intermediate | middle expansion bag, and the downstream expansion bag which were provided in the compression belt | band | zone of FIG. It is sectional drawing which cut | disconnects and shows the upstream expansion bag of FIG. 3, an intermediate | middle expansion bag, and a downstream expansion bag in the width direction. It is a functional block diagram for demonstrating the principal part of the control function with which the electronic control apparatus of FIG. 1 was equipped. The cuff pressure signal Spc indicating the pressure in the cuff that decreases with the passage of time from the start time of blood pressure measurement is illustrated by a broken line, and the compression pressure Pcuff that is a direct current component included in the cuff pressure signal Spc is illustrated by a solid line. FIG. It is a figure which illustrates the cuff volume pulse wave PVR which is an alternating current component included in the cuff pressure signal Spc on a common time axis by a solid line, and illustrates the primary differential waveform PVR 'of the cuff volume pulse wave PVR by a broken line. It is a figure which shows the estimated point of the end systolic pressure ESBP which is a time of the negative minimum point of the primary differential waveform PVR 'of the cuff volume pulse wave PVR showing the minimum value. The cuff volume pulse PVR, its first derivative waveform PVR ′, and the second derivative waveform PVR ″ are shown on a common time axis, and the amplitude A of the cuff volume pulse PVR and the negative derivative waveform PVR ″ are negative. It is a figure which shows the amplitude value d on the cuff volume pulse wave PVR at the time corresponding to the minimum point. It is a time chart explaining the control action of the cuff pressure control part contained in the electronic controller of FIG. It is a figure explaining the definition of the starting point Pf of the cuff volume pulse wave PVR. From one cuff volume pulse wave PVR obtained in a section where the compression pressure Pcuff is lower than the end systolic pressure ESBP, the rising start point Pf of the cuff volume pulse wave PVR and the amplitude of the cuff volume pulse wave PVR are corrected. It is a figure explaining that the diastole synthetic wave PVRdia is produced | generated by subtracting the waveform of the reference wave PVRb (systolic time phase wave PVRsys). A plurality of cuff volume pulse waves PVR obtained in the process in which the compression pressure Pcuff drops below the end-systolic pressure ESBP is corrected so that the rising start point Pf coincides with the amplitude of the cuff volume pulse wave PVR. It is a figure explaining that the diastole synthetic wave PVRdia is produced | generated by subtracting the reference wave PVRb (systolic time phase wave PVRsys). It is a figure which shows the cuff volume pulse wave PVR, the systolic time phase wave PVRsys, and the diastolic synthetic wave PVRdia which are sequentially obtained in the descending process of the compression pressure Pcuff on a common time axis. It is the elements on larger scale which show the vicinity of the maximum amplitude generation | occurrence | production of the expansion period synthetic wave PVRdia of FIG. Using the W oscillometric method, the volume consisting of the cuff volume pulse wave PVR successively obtained during the period of decrease in the compression pressure Pcuff and the systolic time phase wave respectively included in the cuff volume pulse wave at a cuff pressure lower than the end systolic pressure. It is a figure which shows the 1st step difference of the amplitude (envelope) which connects the amplitude value of a pulse wave, the amplitude of the systolic time phase wave of the cuff volume pulse wave PVR, and its inflection point (arrow). Using the W oscillometric method, the volume consisting of the cuff volume pulse wave PVR successively obtained during the period of decrease in the compression pressure Pcuff and the systolic time phase wave respectively included in the cuff volume pulse wave at a cuff pressure lower than the end systolic pressure. It is a figure which shows the 1st difference of the amplitude (envelope) which connects the amplitude value of a pulse wave, the amplitude of the cuff volume pulse wave PVR containing a reflected wave, and several inflection points (arrow). It is a figure explaining the time width T of the main component of the cuff volume pulse wave PVR obtained in the fall period of the compression pressure. It is a flowchart explaining the principal part of the control action by the electronic controller of FIG. It is a correlation figure which shows the minimum blood pressure value DBP measured by the W oscillometric method of the automatic blood pressure measuring device 14 of an Example on a vertical axis | shaft, and shows the minimum blood pressure value DBPdirect measured by the open blood method on a horizontal axis. It is a figure which shows the relationship between the transmural pressure Pt [mmHg] of the biological artery blood vessel, and blood vessel sectional area A [cm < ² >]. It is a figure explaining the relationship of the volume pulse wave output corresponding to the input pressure wave in the PA curve displayed by FIG. It is a figure which shows the relationship between the compression pressure Pcuff which uses pulse pressure PP [mmHg] as a parameter, and the envelope of the amplitude of the volume pulse wave PVR.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the following embodiments, the drawings are appropriately simplified or modified, and the dimensional ratios, shapes, and the like of the respective parts are not necessarily drawn accurately.

  FIG. 1 shows an automatic blood pressure measurement apparatus 14 according to an example of the present invention, which includes a compression band 12 for an upper arm that is wound around a pressed part that is a part of a living body, for example, the upper arm 10 that is one of the limbs of the living body. ing. This automatic blood pressure measurement device 14 pulsates the artery 16 in the process of lowering the compression pressure of the compression band 12 that has been increased to a value sufficient to stop the artery 16 in the upper arm 10 at a predetermined pressure reduction rate. The cuff pressure signal Spc representing the pressure in the compression band 12 including the pressure vibration generated in response to the volume change is read, and the direct current (DC) component, that is, the cuff pressure representing the compression pressure on the upper arm 10 is read from the cuff pressure signal Spc. It separates into Pcuff and the cuff volume pulse wave PVR which is the AC component, and measures the maximum blood pressure value SBP and the minimum blood pressure value DBP of the living body based on the cuff pressure Pcuff and the cuff volume pulse wave PVR.

  FIG. 2 is a partially cutaway view showing the outer peripheral surface of the compression band 12. As shown in FIG. 2, the compression band 12 includes a belt-shaped outer bag 20 made of a synthetic resin fiber outer circumferential side nonwoven fabric 20 a and a inner circumferential side nonwoven fabric (not shown) whose back surfaces are laminated with a synthetic resin such as PVC. An upstream inflatable bag 22, an intermediate inflatable bag 24, which are sequentially accommodated in the width direction within the belt-like outer bag 20 and are made of a flexible sheet such as a soft polyvinyl chloride sheet and can independently press the upper arm 10. A raised pile (not shown) attached to the end of the inner peripheral nonwoven fabric is detachably bonded to a hook and loop fastener 28 attached to the end of the outer peripheral side nonwoven fabric 20a. The upper arm 10 is detachably mounted. When attached to the upper arm 10, the downstream inflation bag 26 is positioned on the downstream side of the artery 16 in the upper arm 10 with respect to the upstream inflation bag 22 and the intermediate inflation bag 24. Further, the intermediate expansion bag 24 is positioned upstream of the downstream expansion bag 26, and the upstream expansion bag 22 is positioned upstream of the downstream expansion bag 26 and the intermediate expansion bag 24. The upstream inflatable bag 22, the intermediate inflatable bag 24, and the downstream inflatable bag 26 have independent air chambers that are connected in the width direction and press the upper arm 10 respectively, and have pipe connecting connectors 32, 34, and 36 is provided on the outer peripheral surface side. The pipe connecting connectors 32, 34, and 36 are exposed to the outer peripheral surface of the compression band 12 through the outer peripheral side nonwoven fabric 20a.

  3 is a plan view showing the upstream expansion bag 22, the intermediate expansion bag 24, and the downstream expansion bag 26 provided in the compression band 12, and FIG. 4 shows them in the width direction, that is, in the direction of arrow a in FIG. It is sectional drawing cut | disconnected. The upstream expansion bag 22, the middle flow expansion bag 24, and the downstream expansion bag 26 are for detecting a pulse wave that is pressure vibration generated in response to a volume change of the artery 16 compressed by them. , Each has a longitudinal shape. 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 expansion bag 24 is disposed at the center in the width direction of the compression band 12 while being sandwiched between the upstream expansion bag 22 and the downstream expansion bag 26. In the state where the compression band 12 is wound around the upper arm 10, the upstream expansion bag 22 and the downstream expansion bag 26 are positioned at a predetermined interval in the longitudinal direction of the upper arm 10, and the intermediate expansion bag 24 is arranged between the upstream expansion bag 22 and the downstream expansion bag 26 so as to be continuous in the longitudinal direction of the upper arm 10.

  As shown in FIG. 4, the intermediate inflatable bag 24 has side edges of a so-called gusset structure on both sides. That is, a pair of folding grooves 24f made of flexible sheets are formed at both ends in the longitudinal direction of the upper arm 10 of the intermediate expansion bag 24 so as to be closer to each other so as to become closer to each other. ing. The adjacent end portions 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 arranged. . Thereby, both ends 24a and 24b of the intermediate expansion bag 24, the adjacent end 22a of the upstream expansion bag 22, and the adjacent end 26a of the downstream expansion bag 26 are overlapped with each other, that is, an overlap structure. Therefore, when the upstream expansion bag 22, the intermediate expansion bag 24, and the downstream expansion bag 26 press the upper arm 10 with equal pressure, a relatively uniform pressure distribution is obtained even in the vicinity of the boundary between them.

  The upstream inflatable bag 22 and the downstream inflatable bag 26 also have side edges of a so-called gusset structure at the end portions 22 b and 26 b opposite to the intermediate inflatable bag 24. That is, the end portions 22b and 26b on the opposite side of the intermediate expansion bag 24 of the upstream expansion bag 22 and the downstream expansion bag 26 are flexibly folded in a direction approaching each other so as to become deeper as they approach each other. Folding grooves 22f and 26f made of a conductive sheet are respectively formed. The sheets constituting the folding grooves 22f and 26f are opposite to each other via connection sheets 38 and 40 having through holes arranged in the upstream expansion bag 22 and the downstream expansion bag 26 so as not to protrude in the width direction. It is connected to the side portion, that is, the portion on the intermediate expansion bag 24 side. As a result, the compression pressure on the artery 16 of the upper arm 10 can be obtained at the end portions 22b and 26b of the upstream expansion bag 22 and the downstream expansion bag 26 in the same manner as the other portions. The compression width is equivalent to the width dimension. The width direction of the compression band 12 is about 12 cm, and since the three upstream expansion bags 22, the intermediate expansion bag 24, and the downstream expansion bag 26 are arranged in the width direction, each is substantially 4 cm. It must be a width dimension of about. In order to generate a sufficient compression function even with such a narrow width dimension, both end portions 24a and 24b of the intermediate expansion bag 24 and adjacent end portions 22a and 26a of the upstream expansion bag 22 and the downstream expansion bag 26 are used. And end portions 22b and 26b of the upstream side expansion bag 22 and the downstream side expansion bag 26 opposite to the intermediate expansion bag 24 are side edges of a so-called gusset structure. Has been.

  Between the end portions 22a and 26a of the upstream expansion bag 22 and the downstream expansion bag 26 on the side of the intermediate expansion bag 24 and the inner wall surfaces of the pair of folding grooves 24f into which they are inserted, that is, the opposite groove side surfaces In addition, longitudinal shielding members 42 having rigidity anisotropy having a bending rigidity in the width direction of the compression band 12 higher than that in the longitudinal direction of the compression band 12 are interposed. The shielding member 42 has the same length as the upstream expansion bag 22 and the downstream expansion bag 26 or the intermediate expansion bag 24.

  The shielding member 42 is, for example, the circumferential direction of the upper arm 10, that is, the compression, in a state where a plurality of resin-made flexible hollow tubes 44 parallel to the longitudinal direction of the upper arm 10, that is, the width direction of the compression band 12, are parallel to each other. The flexible hollow tubes 44 are arranged in a row in the longitudinal direction of the belt 12, and the flexible hollow tubes 44 are directly or indirectly connected to each other by molding or bonding, or indirectly through another member such as a flexible sheet such as an adhesive tape. It is comprised by connecting to. The shielding member 42 is latched by a plurality of latching sheets 46 provided at a plurality of positions on the outer peripheral side of the end portions 22a and 26a of the upstream inflation bag 22 and the downstream inflation bag 26 on the intermediate inflation bag 24 side. Yes.

  Returning to FIG. 1, in the automatic blood pressure measurement device 14, an air pump 50, a quick exhaust valve 52, and an exhaust control valve 54 are connected to the main pipe 56. From the main pipe 56, 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. 64 is branched. The first branch pipe 58 includes a first on-off valve E1 in series for directly opening and closing between the air pump 50 and the upstream expansion bag 22. The main pipe 56 includes a second open / close valve E2 in series for directly opening and closing the air pump 50, the quick exhaust valve 52, the exhaust control valve 54, and the branch pipes. The third branch pipe 64 includes a third on-off valve E3 in series for directly opening and closing the space between the air pump 50 and the downstream expansion bag 26. A first pressure sensor T1 for detecting the pressure value in the upstream expansion bag 22 is connected to the first branch pipe 58, and a second pressure sensor T2 for detecting the pressure value in the intermediate expansion bag 24 is provided. A third pressure sensor T 3 connected to the second branch pipe 62 and detecting the pressure value in the downstream expansion bag 26 is connected to the third branch pipe 64.

  The electronic control unit 70 includes a first pressure sensor T1, a second pressure sensor T2, and a third pressure sensor T3 that indicate the pressure value in the upstream inflation bag 22, that is, the compression pressure value PC1 of the upstream inflation bag 22. 1 cuff pressure signal, second cuff pressure signal indicating the pressure value in the intermediate expansion bag 24, that is, the compression pressure value PC2 of the intermediate expansion bag 24, and pressure value in the downstream expansion bag 26, that is, the compression pressure of the downstream expansion bag 26 A third cuff pressure signal indicating the value PC3 is supplied. The electronic control unit 70 is a so-called microcomputer including a CPU 72, a RAM 74, a ROM 76, an I / O port (not shown), and the like. In the electronic control unit 70, the CPU 72 processes input signals in accordance with a program stored in the ROM 76 in advance using the storage function of the RAM 74, and the electric air pump 50, the quick exhaust valve 52, the exhaust control valve 54, By controlling the first on-off valve E1, the second on-off valve E2, and the third on-off valve E3, the upper arm 10 is compressed with the same compression pressure using the expansion bags 22, 24, and 26, and the compression pressure is reduced. A first cuff pressure signal and a second cuff pressure signal representing the pressures in the inflation bags 22, 24, and 26 respectively generated in response to the volume change of the artery 16 of the upper arm 10 in the process of lowering at a preset speed. The third cuff pressure signal is sampled. Further, the electronic control unit 70 extracts the DC component of the second cuff pressure signal by smoothing the second cuff pressure signal indicating the gradually decreasing cuff pressure and passing the low pass filter, for example. By subtracting the DC component from the cuff pressure signal, a cuff volume pulse wave signal SM2 which is an AC component included in the cuff pressure signal is generated, and based on the cuff volume pulse wave signal SM2 using the W oscillometric method shown below. The systolic pulse wave amplitude envelope of the living body is calculated from the systolic blood pressure value SBP and the diastolic pulse wave amplitude envelope is calculated from the diastolic pulse wave amplitude envelope, and the measurement value as the calculation result is displayed on the display device 78. The electronic control device 70 is also supplied with an output signal from the blood pressure value measurement activation unit 80. The blood pressure value measurement activation unit 80 outputs a command signal for starting blood pressure measurement in response to a manual activation operation using an activation button (not shown) or every preset blood pressure measurement cycle.

  FIG. 5 is a functional block diagram for explaining the main part of the control function provided in the electronic control unit 70. In FIG. 5, the cuff pressure control unit 82 closes the quick exhaust valve 52 and the exhaust control valve 54 when the command signal for starting the blood pressure measurement is supplied from the blood pressure value measurement starting unit 80, and the first on-off valve E 1, By starting the air pump 50 with the second on-off valve E2 and the third on-off valve E3 open, the upstream inflating bag 22, the intermediate inflating bag 24, and the downstream inflating bag 26 are connected to the artery 16 of the upper arm 10. The compression pressure value PC is rapidly raised to a pressure increase target pressure value PCM (for example, 180 [mmHg]) set in advance to a value sufficiently higher than the maximum blood pressure value SBP in the artery 16. For example, the pressure of each expansion bag is increased until the compression pressure value PC2 of the intermediate expansion bag 24 becomes equal to or higher than the pressure increase target pressure value PCM. Subsequently, the cuff pressure control unit 82 uses the exhaust control valve 54 to set the pressure values PC of the upstream expansion bag 22, the intermediate expansion bag 24, and the downstream expansion bag 26 that have been increased to 3-5 [ mmHg / sec] of the upper arm 10 that is gradually depressurized at a predetermined depressurization speed set in advance and compressed with equal pressure by the upstream expansion bag 22, the intermediate expansion bag 24, and the downstream expansion bag 26. Decrease pressure. Then, the cuff pressure control unit 82 sets the measurement end pressure value PCE (for example, 30 [mmHg]) in which the compression pressure value PC2 of the intermediate inflation bag 24 is set to a value sufficiently lower than the minimum blood pressure value DBP in the artery 16. ), The pressure in the upstream expansion bag 22, the intermediate expansion bag 24, and the downstream expansion bag 26 is discharged to atmospheric pressure using the quick exhaust valve 52.

  The cuff pressure signal storage unit 84 includes a first pressure sensor in a process in which the cuff pressure control unit 82 gradually decreases the pressure values PC of the upstream expansion bag 22, the intermediate expansion bag 24, and the downstream expansion bag 26, respectively. The output signals from T1, the second pressure sensor T2, and the third pressure sensor T3, particularly the output signal from the second pressure sensor T2, are used as the cuff pressure signal Spc.

  The cuff volume pulse wave generation unit 86 performs, for example, a substantial low-pass filter process for performing a moving average of an interval of an average period of a pulse wave during blood pressure measurement on the cuff pressure signal Spc, so that the cuff pressure signal Spc A cuff volume, which is an AC component included in the cuff pressure signal Spc, is generated by generating a DC component, that is, a compression pressure (cuff pressure) Pcuff representing a compression pressure on the upper arm 10 and obtaining a difference between the cuff pressure signal Spc and the cuff pressure Pcuff. A pulse wave PVR is generated. For example, the broken line in FIG. 6 indicates the cuff pressure signal Spc, and the solid line in FIG. 6 indicates the compression pressure Pcuff. Moreover, the solid line of FIG. 7 has shown the cuff volume pulse wave PVR.

Systolic end pressure determination unit 88, by the cuff volume pulse PVR e.g. cutoff frequency through a high-pass filter of 0.5 [Hz], mosquitoes mutabilis Sekimyakuha shown in dashed lines and 8 in FIG. 7 First-order differential waveform PVR ′ of PVR is obtained. Next, the compression pressure Pcuff when the negative minimum value of the primary differential waveform PVR ′ is minimized is determined as the end-systolic pressure ESBP of the living heart. The negative minimum value of the first-order differential waveform PVR ′ has the property that the negative minimum value of the first-order differential waveform PVR ′ has the property of being attenuated when the diastolic wave that is a component generated in the diastole of the heart appears. The compression pressure Pcuff at that time is determined as the end-systolic pressure.

  In addition to or in addition to the above, the end systolic pressure determining unit 88 passes the cuff volume pulse wave PVR through, for example, a high-pass filter having a cutoff frequency of 1.0 [Hz] twice as shown in FIG. A second-order differential waveform PVR ″ of the cuff volume pulse wave PVR shown by a two-dot chain line is obtained. Next, it corresponds to the negative minimum point of the second-order differential waveform PVR ″ of the cuff volume pulse wave PVR on the common time axis. The compression pressure Pcuff when the amplitude value d on the cuff plethysmogram PVR at the point of time exceeds a predetermined ratio, for example, 50%, of the amplitude A of the cuff plethysmogram PVR is determined as the end systolic pressure ESBP. To do. This predetermined ratio is obtained experimentally in advance.

The systolic time phase wave generation unit 90, when the compression pressure (cuff pressure) Pcuff in the compression band 12 (intermediate inflation bag 24) in the series of cuff volume pulse waves PVR is the end-systolic pressure ESBP of the living heart. The plethysmogram generated one time before the end-systolic pressure plethysmogram PVR _ESBP, which is one cuff plethysmogram PVR, is used as the reference wave PVRb, and the compression pressure Pcuff is equal to or lower than the end-systolic end-pressure ESBP The amplitude of the reference wave PVRb is adjusted to be equal to the amplitude of the superposition start point of the diastolic synthesized wave PVRdia included in the cuff volume pulse wave PVR among the cuff volume pulse waves PVR obtained sequentially when Each (corrected) systolic time phase wave PVRsys is generated. That is, the systolic time phase wave generation unit 90 includes the compression pressure (cuff pressure) Pcuff in the compression band 12 (intermediate inflation bag 24) of the series of cuff volume pulse waves PVR as the end-systolic pressure ESBP of the living heart. a reference wave determination unit 92 as a reference wave PVRb the volume pulse wave generated in one before the one cuff volume pulse PVR is a systolic end container Sekimyakuha PVR _ESBP that occurred when a certain, pressing pressure ( Cuff pressure) The zero-crossing point of the second-order differential wave PVR of the cuff volume pulse wave PVR obtained in the interval where Pcuff is lower than the end-systolic pressure ESBP of the living heart and the first-order differential wave PVR ′. A reflected wave superimposition start point determination unit 94 that determines a point on the base line BL of the cuff volume pulse wave PVR corresponding to the minimum point as a reflected wave superimposition start point Prs, and compression pressure (cuff pressure) Pcuff is a contraction of the heart of the living body End of term pressure ESB When one of the cuff plethysmogram PVR and the reference wave PVRb obtained in a plurality of lower intervals is made to coincide with each other at the rising start point (foot point) Pf on a common time axis If the reflected wave superposition start point is behind the maximum amplitude time of the reference wave of the phase wave, the maximum amplitude value of the reference wave is A _ESBP , the cuff volume pulse wave amplitude at that time is A _PVR , and the previous reflection When the wave superposition start point exists in the pulse wave rising leg before the maximum amplitude time of the reference wave, the amplitude value at the reflected wave superposition start point of the cuff volume pulse wave is A _PVR , and the reference wave the amplitude value at the reflected wave overlap starting point as _{a ESBP,} the amplitude ratio _{a ratio (= a PVR / a} ESBP) and determined for each individual cuff volume pulse PVR, the maximum amplitude value of the reference wave and the amplitude ratio _{a ratio} A _ESB And a reference wave correction unit 96 that generates a systolic time phase wave PVRsys by correcting _{P so} as to make the amplitude of the reference wave PVRb coincide with the amplitude of each cuff volume pulse wave PVR.

  FIG. 10 is a diagram for explaining a method for determining the reflected wave superposition start point Prs in the cuff volume pulse wave PVR in the reflected wave superposition start point determination unit 94. In FIG. 10, in the first-order differential wave PVR ′ of the cuff volume pulse wave PVR and the second-order differential wave PVR ″ of the cuff volume pulse wave PVR on the common time axis, the zero-cross point Z of the second-order differential wave PVR ″ and the first-order wave A minimum point PB of the differential wave PVR ′ is obtained, and the inflection on the base line BL of the cuff volume pulse wave PVR corresponding to the zero cross point Z of the secondary differential wave PVR ″ and the minimum point PB of the primary differential wave PVR ′. The point is determined as the reflected wave superposition start point Prs.

  Further, in the reference wave correction unit 96, rising start points (foot points) Pf of the cuff volume pulse wave PVR and the reference wave PVRb are obtained as shown in FIG. For example, in the cuff volume pulse wave PVR shown in FIG. 11, a straight line L connecting a point P20 corresponding to 20 [%] of the amplitude of the cuff volume pulse wave PVR and a point P50 corresponding to 50 [%] is a cuff volume. A point that intersects the base line BL of the pulse wave PVR is determined as a rising start point (foot point) Pf of the reference wave PVRb.

The diastolic synthetic wave generation unit 98 matches the rising start point Pf of each cuff plethysmogram PVR obtained sequentially in a section where the compression pressure Pcuff is lower than the end-systolic pressure ESBP, and the cuff plethysmogram PVR The diastolic composite wave PVRdia is obtained by subtracting the waveform of the reference wave PVRb, that is, the systolic phase wave PVRsys (= A _ratio × PVRb) corrected to match the amplitude, as shown in FIG. 12 or FIG. Generate each. In FIG. 12, a reference wave PVRb, that is, a systolic time phase wave PVRsys (shown by a broken line) corrected to match the amplitude from the cuff volume pulse wave PVR indicated by a two-dot chain line for one waveform. The diastolic synthetic wave PVRdia generated by subtracting the waveform is shown by a solid line. In FIG. 13, a plurality of cuff volume pulse waves PVR obtained in the process in which the compression pressure Pcuff drops below the end-systolic pressure ESBP is indicated by a two-dot chain line, and the rising start points Pf of the cuff volume pulse waves PVR coincide with each other. In addition, the reference wave PVRb corrected to match the amplitude of the cuff volume pulse wave PVR, that is, the systolic time phase wave PVRsys is indicated by a broken line, and the systolic time wave PVRsys is subtracted from the cuff volume pulse wave PVR. The obtained diastolic synthetic wave PVRdia is indicated by a solid line. The diastolic synthesized wave PVRdia is a synthesized wave of a reflected wave reflected from the branch point of the artery and a diastolic time phase wave generated in the diastole. The arrows in FIG. 13 indicate the time point corresponding to the end systolic pressure ESBP and the end systolic pressure volume pulse wave PVR _ESBP .

  The diastolic blood pressure value determining unit 100 calculates the diastolic blood pressure DBP of the living body based on the amplitude change of the diastolic synthesized wave PVRdia generated by the diastolic synthesized wave generating unit 98 using the W oscillometric method. The diastolic blood pressure determining unit 100, for example, a plurality of dilations obtained by subtracting the systolic time phase wave PVRsys from each cuff volume pulse wave PVR sequentially obtained in the process in which the compression pressure Pcuff is lower than the end systolic pressure ESBP. The period synthesized wave PVRdia decreases after the amplitude increases to the maximum amplitude in time series. The diastolic blood pressure value determining unit 100 generates the diastolic synthesized wave PVRdia one after the diastolic synthesized wave indicating the maximum amplitude among the series of diastolic synthesized waves PVRdia generated by the diastolic synthesized wave generating unit 98. Is determined as the minimum blood pressure DBP. In FIG. 14, the portion of the cuff volume pulse wave PVR sequentially obtained in the decreasing process of the compression pressure Pcuff is indicated by a broken line, and the non-overlapping portion is indicated by a two-dot chain line. The wave PVRsys is indicated by a broken line, and the diastolic synthesized wave PVRdia is indicated by a solid line. The diastolic wave is obtained by extracting the waveform of the diastole region from the rising point of the previous pulse wave in the time region after 300 [msec] from the diastolic synthetic wave. FIG. 15 is a partially enlarged view showing the vicinity of the maximum amplitude occurrence time of the diastolic wave PVRdia extracted and separated in FIG. The arrows in FIGS. 14 and 15 indicate the generation time of the diastolic wave PVRdia generated after the diastolic wave PVRdia indicating the maximum amplitude, that is, the time corresponding to the compression pressure Pcuff determined as the diastolic blood pressure value DBP. Yes.

  The systolic blood pressure value determination unit 102 uses the W oscillometric method to, for example, convert the cuff volume pulse wave PVR obtained sequentially during the decrease period of the compression pressure Pcuff and the cuff volume pulse wave at a cuff pressure lower than the end systolic pressure, respectively. Amplitude ratio obtained by normalizing the amplitude of the systolic time phase wave by its maximum pulse amplitude value in the vicinity of the inflection point of the envelope (envelope) connecting the amplitude values of the volume pulse wave composed of the systolic time phase wave is predetermined. The compression pressure Pcuff corresponding to the pulse wave having the amplitude ratio is determined as the maximum blood pressure value SBP. FIG. 16 shows a black point indicating the first difference point of the amplitude of the systolic time phase wave of the cuff volume pulse wave PVR and an arrow indicating the inflection point. In FIG. 17, a black point indicating a first difference point of the amplitude of the cuff volume pulse wave PVR including the reflected wave and a plurality of inflection points are indicated by arrows. FIG. 18 shows the time width T of the main component of the volume pulse wave PVR.

  FIG. 19 is a flowchart for explaining a main part of the control operation of the electronic control unit 70. When a power switch (not shown) is turned on, the initial state is set. In this initial state, the first on-off valve E1, the second on-off valve E2, the third on-off valve E3, and the quick exhaust valve 52 are normally open, so that they are open (non-operating state), and the exhaust control valve 54 is Since it is a normally closed valve, it is in a closed state (non-operating state), and the air pump 50 is in a non-operating state.

  Next, when a startup operation device (not shown) is operated and the measurement operation of the automatic blood pressure measurement device 14 is started, first, the steps in FIG. 19 corresponding to the cuff pressure control unit 82 (hereinafter, “step” is omitted). In S1, the compression pressure value of the compression band 12 is increased. Specifically, the quick exhaust valve 52 is closed, and the air pump 50 is activated, and the upstream expansion bag communicated with the compressed air compressed from the air pump 50 and in the main pipe 56. 22, the pressure in the intermediate expansion bag 24 and the downstream expansion bag 26 is rapidly increased. Then, compression of the upper arm 10 by the compression band 12 is started.

  Subsequent to S1, in S2 corresponding to the cuff pressure control unit 82, based on the cuff pressure signal PK2 indicating the compression pressure value PC2 of the intermediate inflatable bag 24, the compression pressure value PC2 is higher than the maximum blood pressure value of the living body. It is determined whether or not a pressure increase target pressure value PCM (for example, 180 [mmHg]) that is set in advance so as to be higher. The determination of S2 is negative, and S1 and subsequent steps in FIG. 19 are repeatedly executed.

  However, if the determination in S2 is affirmative, the operation of the air pump 50 is stopped in S3 corresponding to the cuff pressure control unit 82. Then, the pressurized pressure values PC1, PC2, and PC3 of the boosted upstream expansion bag 22, intermediate expansion bag 24, and downstream expansion bag 26 are set to predetermined gradual values set in advance to 3 to 5 [mmHg / sec], for example. The exhaust control valve 54 is actuated so as to simultaneously reduce the pressure at the fast step-down speed, and the slow exhaust is started. As a result, as shown in FIG. 6, the cuff pressure signal Spc is decreased, and the compression pressure Pcuff is decreased.

  Subsequent to S3, in S4 corresponding to the cuff pressure signal storage unit 84, the cuff pressure signal Spc is stored in the RAM 74 while the compression pressure values PC1, PC2, and PC3 are respectively lowered at a predetermined step-down speed. Next, in S5 corresponding to the cuff pressure control unit 82, it is determined whether or not the cuff pressure signal Spc is equal to or less than a preset measurement end pressure value PCE (for example, 30 [mmHg]). While the determination of S5 is negative, the steps after S3 of FIG. 19 are repeatedly executed. When the determination of S5 is positive, in S7 corresponding to the cuff pressure control unit 82, the upstream expansion bag 22, intermediate The quick exhaust valve 52 is operated so that the pressure in the expansion bag 24 and the downstream expansion bag 26 is discharged to atmospheric pressure.

  Subsequently, in S7 corresponding to the cuff volume pulse wave generation unit 86, a substantive low-pass filter that performs, for example, a moving average of intervals of an average period of a pulse wave during blood pressure measurement on the cuff pressure signal Spc stored in the RAM 74. By performing the processing, a compression pressure (cuff pressure) Pcuff indicating the compression pressure on the DC component, that is, the upper arm 10 is generated from the cuff pressure signal Spc. Further, by obtaining the difference between the cuff pressure signal Spc and the compression pressure (cuff pressure) Pcuff, a cuff volume pulse wave PVR that is an AC component included in the cuff pressure signal Spc is generated.

Next, step S8 corresponding to the systolic end pressure determination unit 88, that the cuff volume pulse PVR is for example cut-off frequency is passed through a high-pass filter of 0.5 [Hz], mosquitoes mutabilis Sekimyakuha A primary differential waveform PVR ′ of PVR is obtained. Then, the compression pressure Pcuff when the negative minimum value of the primary differential waveform PVR ′ is minimized is determined as the end systolic pressure ESBP of the living heart.

  In S8 corresponding to the end systolic pressure determining unit 88, in addition to or instead of the above, the cuff volume pulse wave PVR is passed through a high-pass filter having a cutoff frequency of 1.0 [Hz] twice, for example. Thus, the second-order differential waveform PVR ″ of the cuff volume pulse wave PVR is obtained. On the common time axis, the time point corresponding to the negative minimum point of the second-order differential waveform PVR ″ of the cuff volume pulse wave PVR The compression pressure Pcuff when the amplitude value d on the cuff volume pulse wave PVR exceeds a predetermined ratio, for example, 50 [%] of the amplitude A of the cuff volume pulse wave PVR is determined as the end systolic pressure ESBP. Is done. When the reflected wave overlaps the systolic time phase wave prior to the diastolic wave, and the point where the negative minimum value of the first derivative waveform of the cuff volume pulse wave is minimized extends to the diastolic time phase, for example, When the negative minimum point of the first-order differential waveform exceeds 260 [msec] from the rising point of the cuff volume pulse wave, the compression pressure Pcuff when the negative minimum point becomes the minimum is the contraction of the living heart. Instead of the end-term pressure ESBP, the end-systolic pressure ESBP determined from the compression pressure Pcuff when the amplitude d exceeds 50% of the amplitude A of the cuff volume pulse wave PVR is used.

  Next, in S9 corresponding to the systolic time phase wave generator 90, the compression pressure (cuff pressure) Pcuff in the compression band 12 (intermediate inflation bag 24) in the series of cuff volume pulse waves PVR is contraction of the living heart. The plethysmogram generated immediately before the end-systolic pressure plethysmogram PVRsys, which is one cuff plethysmogram PVR generated at the end-term pressure ESBP, is used as the reference wave PVRb, and the compression pressure Pcuff is the living body pressure. Among the cuff plethysmograms PVR sequentially obtained when the end-systolic pressure ESBP is equal to or less than the end-systolic pressure ESBP, the reference is set to be equal to the amplitude of the superposition start point of the diastolic synthesized wave PVRdia included in the cuff plethysmogram PVR The systolic time phase wave PVRsys in which the amplitude of the wave PVRb is adjusted (corrected) is generated.

Next, in S10 corresponding to the diastolic synthetic wave generation unit 98, the rising start point Pf of each cuff volume pulse wave PVR obtained sequentially in a section where the compression pressure Pcuff is lower than the end systolic pressure ESBP and The diastolic composite wave PVRdia is obtained by subtracting the waveform of the reference wave PVRb, that is, the systolic time phase wave PVRsys (= A _ratio × PVRb) corrected to match the amplitude of the cuff volume pulse wave PVR, respectively. Alternatively, they are generated as shown in FIG.

  In S11 corresponding to the diastolic blood pressure determining unit 100, the waveform of the diastolic region of the diastolic synthetic wave generated by the diastolic synthetic wave generating unit 98 is 300 [msec] or later from the rising point of the previous pulse wave. For the diastolic wave extracted in the time domain, the diastolic wave PVRdia that is one after the diastolic wave that indicates the maximum amplitude in the series of diastolic waves PVRdia is determined, and the generation of the diastolic wave PVRdia after that The compression pressure Pcuff corresponding to the time point is determined as the minimum blood pressure value DBP.

  In S12 corresponding to the systolic blood pressure value determining unit 102, the cuff volume pulse wave PVR sequentially obtained during the decrease period of the compression pressure Pcuff and the systolic time phase included in the cuff volume pulse wave at the cuff pressure lower than the end systolic pressure are respectively. A pulse whose predetermined amplitude ratio is the vicinity of the inflection point of the envelope (envelope) connecting the amplitude values of the volume pulse wave composed of waves, or the amplitude ratio obtained by normalizing the amplitude of the systolic time phase wave with the maximum pulse amplitude value The compression pressure Pcuff corresponding to the wave is determined as the maximum blood pressure value SBP. In S13, blood pressure data indicating the systolic blood pressure value SBP and the diastolic blood pressure value DBP determined as described above is output, and the systolic blood pressure value SBP and the diastolic blood pressure value DBP are displayed on the display device 78. .

  As described above, according to the automatic blood pressure measurement device 14 of the present embodiment, the systolic time phase wave PVRsys is subtracted from the cuff volume pulse wave PVR sequentially obtained in the section of the compression pressure Pcuff lower than the end systolic pressure. Thus, the diastolic synthetic wave PVRdia included in the cuff volume pulse wave PVR is extracted, and the diastolic wave PVRdia of the diastolic region of the diastolic synthetic wave is calculated to calculate the diastolic blood pressure DBP of the living body. Therefore, since the diastolic wave having a small amplitude of about a fraction of the systolic phase wave PVRsys included in the cuff volume pulse wave PVR is used for determining the diastolic blood pressure value DBP, the diastolic wave value DBP is high. Measurement accuracy is obtained. Incidentally, FIG. 20 is a diagram in which the abscissa represents the diastolic blood pressure value DBPdirect measured by the open blood method, and the ordinate represents the diastolic blood pressure value DBP determined as described above, and shows a high correlation with each other. There is no error.

Further, according to the automatic blood pressure measurement device 14 of the present embodiment, the DC component of the cuff pressure signal Spc is obtained by performing a low-pass filter process for performing a moving average process at intervals of an average period of a pulse wave during blood pressure measurement, for example. the compressive pressure Pcuff extracted, the cuff volumetric pulse wave generator 86 for generating a mosquito mutabilis Sekimyakuha PVR by obtaining the difference of the cuff pressure signal Spc and compressive pressure Pcuff its DC component, mosquitoes mutabilis An end-systolic pressure determining unit 88 that determines a compression pressure (cuff pressure) Pcuff as the end-systolic pressure ESBP when the negative minimum point of the first-order differential waveform PVR ′ of the product pulse PVR is minimized. . For this reason, the cuff volume pulse wave PVR synchronized with the heartbeat of the living body and the end-systolic pressure ESBP of the living body can be easily obtained.

  Further, according to the automatic blood pressure measurement device 14 of the present embodiment, the end-systolic pressure determining unit 88 corresponds to the negative minimum point of the second-order differential waveform PVR ″ of the cuff volume pulse wave PVR on the common time axis. The compression pressure (cuff pressure) Pcuff when the amplitude value d on the cuff volume pulse wave PVR at the time exceeds 50% of the amplitude A of the cuff volume pulse wave PVR is determined as the end-systolic pressure ESBP. For this reason, the reflected wave overlaps the systolic time phase wave before the diastole wave, and the point where the negative minimum of the first derivative waveform of the early cuff volume pulse wave is minimized extends to the diastole time phase However, the end-systolic pressure ESBP is accurately determined, and the compression pressure (cuff pressure) Pcuff when the negative minimum value of the first-order differential waveform PVR ′ of the cuff plethysmogram PVR is minimized becomes the end-systolic pressure ESBP. When determining as a superposition of reflected waves Thus may become unclear at the negative minimum point is broad, there are cases where minimum point is not multiple occurrence or to systolic end pressure ESBP precision obtained.

In addition, according to the automatic blood pressure measurement device 14 of the present embodiment, the systolic time phase wave generation unit 90 is one before the end systolic pressure volume pulse wave PVR _ESBP generated when the end systolic pressure ESBP. In this case, the cuff volume pulse wave generated _immediately before the end-systolic pressure volume pulse wave PVR _ESBP is determined. Since it is a pure volume pulse wave that is not affected by the reflected wave or the diastolic time phase wave, the shape of the diastolic synthesized wave PVRdia obtained from such a reference wave PVRb becomes accurate, and the diastolic synthesized wave PVRdia is obtained. The accuracy of the diastolic blood pressure value DBP measured based on this is further enhanced.

In addition, according to the automatic blood pressure measurement device 14 of the present embodiment, the systolic time phase wave generation unit 90 starts from the rising leg of the cuff volume pulse wave PVR obtained with the compression pressure Pcuff lower than the end systolic pressure ESBP. And the inflection point of the cuff volume pulse wave PVR corresponding to the minimum point of the first-order differential wave PVR ′ and the zero-crossing point of the second-order differential wave PVR ″ going from positive to negative is determined as the reflected wave superposition start point Prs. The reflected wave superposition start point determination unit 94 and the cuff volume pulse wave PVR obtained at the compression pressure Pcuff lower than the end systolic pressure ESBP and the reference wave PVRb are matched with each other on the common time axis. If the reflected wave superposition start point is delayed from the maximum amplitude time of the reference wave of the systolic time phase wave, the maximum amplitude value of the reference wave is A _ESBP, and the cuff volume pulse wave at that time the amplitude _{a P} And _R, when year reflected waves overlap starting point exists pulse wave rising phase prior to maximum amplitude time of the reference wave, and the amplitude value at the reflected wave overlap starting point of the cuff plethysmography and A _PVR, The amplitude value A _ratio (= A _PVR / A _ESBP ) is obtained by _{setting the} amplitude value of the reference wave at the reflection wave superimposition start point as A _ESBP , and the contraction period is obtained by multiplying the reference wave PVRb by the amplitude ratio A _ratio. A reference wave correction unit 96 that generates a time phase wave PVRsys, and therefore, a systolic time phase wave PVRsys included in the cuff volume pulse wave PVR obtained at a compression pressure Pcuff lower than the end systolic pressure ESBP. Can be easily obtained.

  Further, according to the automatic blood pressure measurement device 14 of the present embodiment, the diastolic synthetic wave generation unit 98 is sequentially obtained when the compression pressure Pcuff is equal to or lower than the end systolic pressure ESBP of the living body on the common time axis. By subtracting the shape (amplitude) of the systolic phase wave PVRsys generated for each from the shape (amplitude) of the cuff volume pulse wave PVR, each diastolic composite wave PVRdia is sequentially reduced in the compression pressure Pcuff decreasing process. It is generated. Therefore, a plurality of diastolic synthesized waves PVRdia can be easily obtained in time series.

  Further, according to the automatic blood pressure measurement device 14 of the present embodiment, the diastolic blood pressure value determining unit 100 has a diastolic period that indicates the maximum amplitude of the series of diastolic synthesized waves PVRdia generated by the diastolic synthesized wave generating part 98. The compression pressure Pcuff corresponding to the diastolic synthetic wave PVRdia generated after the synthetic wave PVRdia is determined as the minimum blood pressure value. For this reason, the correlation with the lowest blood pressure value obtained by Korotkoff blood pressure measurement using the open method, that is, the direct method using a catheter, is further enhanced, and measurement accuracy without a tendency error is obtained.

  Further, according to the automatic blood pressure measurement device 14 of the present embodiment, the cuff volume pulse PVR sequentially obtained during the decrease period of the compression pressure Pcuff and the cuff pressure lower than the end systolic pressure ESBP are included in the cuff volume pulse wave, respectively. Near the inflection point of the envelope (envelope) that connects the amplitude values of the volume pulse wave consisting of the systolic time phase wave, or the amplitude ratio obtained by normalizing the amplitude of the systolic time phase wave with its maximum pulse amplitude value is a predetermined amplitude A systolic blood pressure value determining unit 102 that determines the compression pressure Pcuff corresponding to the pulse wave as the ratio as the systolic blood pressure value SBP is included. Therefore, since the systolic blood pressure value is determined by using the systolic time phase component of the cuff volume pulse wave, the amplitude of the pulse waveform on which the reflected wave of the cuff volume pulse wave is superimposed increases, and a plurality of inflection points are added to the envelope. If the oscillometric method determines the systolic blood pressure value SBP under the condition that the reflected wave component is included in the maximum amplitude of the pulse waveform, the accuracy of the systolic blood pressure value SBP is improved.

  As mentioned above, although one Example of this invention was described in detail with reference to drawings, this invention is not limited to this Example, It can implement in another aspect.

For example, in the systolic time phase wave generation unit 90 of the above-described embodiment, the end systolic pressure volume pulse wave PVR _ESBP which is a volume pulse wave generated when the compression pressure Pcuff by the compression band 12 is the end systolic pressure _ESBP. The plethysmogram generated one time before was used as the reference wave PVRb. However, since the reference wave PVRb may be a volume pulse wave having a precise shape representative of the systole that does not include the diastolic synthesized wave PVRdia component, a slight decrease in accuracy that does not cause a practical problem is allowed. In this case, the end-systolic pressure volume pulse wave PVR _ESBP itself may be used as the reference wave PVRb, or the volume pulse wave generated _immediately after the end-systolic pressure volume pulse wave PVR _ESBP may be used as the reference wave PVRb. In short, the volume pulse wave leading to volume pulse or systolic end container Sekimyakuha _{PVR ESBP} adjacent systole end container Sekimyakuha _{PVR ESBP} may be used as the reference wave PVRb.

  In the diastolic blood pressure value determination unit 100 of the above-described embodiment, when the diastolic blood pressure value DBP is determined, the diastolic synthetic wave PVRia generated one time after the diastolic synthetic wave PVRdia having the maximum amplitude d is detected. The compression pressure Pcuff was determined as the minimum blood pressure value DBP. However, if a slight decrease in accuracy with no practical problem is allowed, the compression pressure Pcuff at the time of generation of the diastolic synthetic wave PVRdia having the maximum amplitude may be determined as the minimum blood pressure value DBP.

  In addition, the compression band 12 used in the above-described embodiment includes the upstream expansion bag 22, the intermediate expansion bag 24, and the downstream expansion bag 26 that can independently compress the upper arm 10. One inflatable bag may be provided.

  In the above-described embodiment, the cuff pressure control unit 82 sets the compression pressure value PC of the upstream expansion bag 22, the intermediate expansion bag 24, and the downstream expansion bag 26 to a constant value of about 3 to 5 [mmHg / sec], for example. However, step pressure reduction may be performed so that a pulse wave is collected in a process in which the compression pressure of the compression band 12 is maintained at a constant value.

  It should be noted that the above description is merely an embodiment, and other examples are not illustrated. However, the present invention should be implemented in variously modified and improved modes based on the knowledge of those skilled in the art without departing from the gist of the present invention. Can do.

10: Upper arm (stressed part of living body)
12: compression band 14: automatic blood pressure measurement device 16: artery 24: intermediate inflation bag DBP: minimum blood pressure value SBP: maximum blood pressure value Spc: cuff pressure signal Pcuff: compression pressure (cuff pressure)
PVR: Cuff volume pulse wave PVR ′: First-order differential wave PVR of cuff volume pulse wave “Second-order differential wave of cuff volume pulse wave ESBP: End-systolic pressure PVR _ESBP : End-systolic pressure volume pulse Prs: Reflected wave superposition Starting point PVRb: Reference wave PVRsys: Systolic phase wave PVRdia: Diastolic synthesized wave

Claims (7)

A cuff pressure signal representing the compression pressure obtained in the process of reducing the compression pressure of the compression band, comprising a compression band wound around a part of the living body to reduce the compression pressure on the part of the biological body An automatic blood pressure measurement device for measuring a minimum blood pressure value of the living body based on a cuff volume pulse wave that is an alternating current component synchronized with the pulse of the living body,
Which is a cuff volume Sekimyaku wave systolic end pressure and volume pulse wave or one volume pulse wave connected to it when the cuff pressure is systolic end pressure of the body of said cuff volume pulse as a reference wave, the The reference wave is set so that the cuff pressure is equal to or less than the amplitude of the superimposed start point of the reflected wave included in the cuff volume pulse wave obtained sequentially when the cuff pressure is equal to or lower than the end-systolic pressure of the living body. A systolic time phase wave generating unit for generating the adjusted systolic time phase wave,
A diastolic composite wave is generated by subtracting the generated systolic time phase waveform from the waveform of each cuff volume pulse wave sequentially obtained when the cuff pressure is equal to or lower than the end systolic pressure of the living body. Diastolic synthetic wave generator,
An automatic blood pressure measurement device comprising: a minimum blood pressure value determination unit that determines a minimum blood pressure value of the living body based on the amplitude of the generated diastolic synthetic wave. A DC component that is a compression pressure applied to a part of the living body field is extracted from the cuff pressure signal by performing a low-pass filter process that performs a moving average process at intervals of the average period of the pulse wave during blood pressure measurement, and the cuff pressure signal a cuff volumetric pulse wave generator generating the mosquito mutabilis product pulse wave by obtaining the difference between the DC component and,
Determining the cuff pressure when the negative minimum value of the primary differential waveform arising in response to the inflection point of the systolic wave descending limb of the mosquito mutabilis Sekimyakuha for continuous is minimized as the systolic end pressure The automatic blood pressure measuring device according to claim 1, further comprising: an end systolic pressure determining unit. The end systolic pressure determining unit determines the detection of the inflection point of the primary differential waveform of the cuff volume pulse wave on the common time axis based on the minimum point of the secondary differential waveform, and determines the negative of the secondary differential waveform. The cuff pressure when the amplitude value of the cuff volume pulse wave corresponding to the minimum point of the cuff exceeds 50 [%] of the maximum amplitude of the cuff volume pulse wave is determined as the end systolic pressure. Item 2. The automatic blood pressure measurement apparatus according to Item 2. The systolic time phase wave generation unit,
Corresponding to the zero-crossing point of the second-order differential wave from the rising leg of the cuff volume pulse wave obtained at the cuff pressure lower than the end-systolic pressure at the end of systole to the top of the head, and corresponding to the minimum point of the first-order differential wave, A reflected wave superposition start point determination unit that determines the inflection point of the cuff volume pulse wave as a reflected wave superposition start point;
A reference wave of the systolic time phase wave when the cuff volume pulse wave obtained at a cuff pressure lower than the end systolic pressure and the reference wave are coincident with each other on the rising start point on a common time axis If the reflected wave superimposition start point is later than the maximum amplitude time, the maximum amplitude value of the reference wave is AESBP, the cuff volume pulse wave amplitude at that time is APVR, and the previous reflected wave superposition start point is the reference wave When the pulse wave rise leg before the maximum amplitude time is APVR, the amplitude value of the cuff volume pulse wave at the reflection wave superposition start point is APVR, and the amplitude value of the reference wave at the reflection wave superposition start point AESBP is used as an AESBP, an amplitude ratio Aratio (= APVR / AESBP) is obtained, and the reference wave correction unit that generates the systolic time phase wave by multiplying the reference wave by the amplitude ratio Aratio is included. The automatic blood pressure measuring device according to any one of claims 1 to 3.   The diastolic synthesized wave generating unit is generated for each of the cuff volume pulse wave amplitude obtained sequentially when the cuff pressure is equal to or lower than the end-systolic pressure of the living body on the common time axis. 5. The automatic blood pressure measurement device according to claim 1, wherein each diastolic composite wave is sequentially generated in the process of decreasing the cuff pressure by subtracting the amplitude of the systolic time phase wave. The diastolic blood pressure value determining unit includes a cuff pressure corresponding to a diastolic synthesized wave one after the diastolic synthesized wave indicating the maximum amplitude in a series of diastolic synthesized waves generated by the diastolic synthesized wave generating unit. Is determined as the minimum blood pressure value, the automatic blood pressure measuring device according to any one of claims 1 to 5.   In the cuff volume pulse wave sequentially obtained during the cuff pressure drop period and the cuff pressure lower than the end systolic pressure, the envelope linking the amplitude value of the volume pulse wave composed of the systolic time phase wave respectively included in the cuff volume pulse wave Determination of systolic blood pressure value that determines the cuff pressure corresponding to the pulse wave that has a predetermined amplitude ratio near the inflection point or the amplitude ratio obtained by normalizing the amplitude of the systolic time phase wave with the maximum pulse amplitude value The automatic blood pressure measurement device according to claim 1, further comprising a unit.

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