JP5907638B2 - Arterial vascular stiffness measuring device - Google Patents

Description

  The present invention relates to an arterial vascular stiffness measuring apparatus for measuring the degree of arterial vascular stiffness of a living body using a pulse wave generated in synchronization with a pulse from a compression band wound around a part of the living body. .

  The blood pressure value and pulse wave velocity of the living body are measured as living body circulatory information and are used for diagnosis of the living body. However, they are easily affected by factors other than the degree of arteriosclerosis of the living body, and are directly It was not something that was expressed. For this reason, it is required to directly measure the degree of arterial vascular stiffness or arterial vascular flexibility (compliance) that directly represents arteriosclerosis of a living body.

  On the other hand, as shown in Patent Document 1, a hemodynamic measurement device has been proposed. In this hemodynamic measurement device, the maximum value appearing periodically in the cuff pressure differential signal is connected in the two-dimensional coordinates of the horizontal axis indicating the cuff pressure value as the compression pressure by the compression band and the vertical axis indicating the cuff pressure differential value. Hemodynamics related to the degree of hardening of the arterial blood vessel is evaluated using an envelope E (envelope) E and a feature amount G corresponding to the sharpness of the envelope E. The maximum value of the cuff pressure differential signal corresponds to the maximum inclination of the rising leg of the pulse wave. When arteriosclerosis proceeds, the envelope E becomes trapezoidal and the sharpness of the envelope E decreases. According to this, the characteristic amount G indicating the hemodynamics of the living body is quantitatively evaluated, but the characteristic amount G is also affected by other parameters such as hypotension, arrhythmia, heart disease, etc. Sufficient accuracy cannot be obtained for evaluation of the degree of cure.

  Further, as shown in Patent Document 2, a is the distance from the starting point to the apex of the first peak of the acceleration pulse wave obtained by second-order differentiation of the waveform of the photoelectric pulse wave, and the second from the waveform of the rising part of the acceleration pulse wave The distance from the base line of the waveform to the apex is b, the distance from the base line of the third waveform to the apex is c from the waveform of the rising part of the acceleration pulse wave, and the base line of the fourth waveform from the waveform of the rising part of the acceleration pulse wave When the distance to the apex is d, (d / a)-(b / a) is defined as arterial vascular aging score 1, and (c / a)-(b / a) is defined as arterial vascular aging score 2. Thus, a method for evaluating the degree of arterial vascular sclerosis using the arterial vascular aging scores 1 and 2 has been proposed. In the ascending leg of the pulse wave obtained from a normal artery, it rapidly increases in a quadratic function as the pressure increases, and the arterial vessel cross section is circular, but in the ascending leg of the pulse wave when arteriosclerosis is established, the pressure is increased. As it increases, it increases linearly and the arterial blood vessel cross section tends to be flat. -(B / a) included as the second term in the arterial vascular aging scores 1 and 2 indicates non-linearity in the pulse wave rising leg. Note that the acceleration pulse wave is measured mainly in peripheral arteries such as fingertips, and is difficult to measure in thick arteries such as the upper arm.

Japanese Patent No. 3480703 JP 2002-238867 A

  By the way, the above-described conventional evaluation of arterial vascular stiffness is based on the premise that the arterial blood vessels harden with age, assuming a single element model consisting of a single spring whose spring constant increases with age. In addition, it is difficult to evaluate in accordance with the actual phenomenon that arterial blood vessels are softly measured in relation to the severity of arteriosclerosis, and sufficient accuracy has not been obtained for the evaluation of arterial vascular sclerosis.

  The present invention has been made in the background of the above circumstances, and its object is to provide a cuff pulse obtained from a compression band by applying a predetermined compression pressure from a compression band wound around a part of a living body. An object of the present invention is to provide an arterial vascular stiffness measuring apparatus capable of accurately obtaining the degree of hardening of an artery when measuring the compliance (flexibility) of an arterial blood vessel under a cuff using a wave.

  The present inventor examines the above situation as a background. The cuff pulse wave is a plethysmogram, and the difference between the arterial pressure and the compression pressure by the cuff, that is, the arterial vascular wall internal / external pressure difference PT (Transmural Pressure). Recognizing that it was volumetric vibration of arterial blood vessels induced by pulse wave, we examined the qualitative evaluation method of the rising leg of pulse wave shape, and examined the index which shows the degree of arterial blood vessel sclerosis accurately. And we found that it is necessary to consider the stress of the arterial vessel wall when "force" as a pulse wave is applied, and the three-element model of the arterial vessel that evaluates viscoelasticity based on the tissue constituting the arterial vessel wall Was assumed as shown in FIG. That is, the aorta has a high vascular compliance and is known as an elastic artery, whereas the brachial artery has a low vascular compliance under physiological conditions and is considered a muscular artery. It has been found that vascular compliance under physiological conditions can be measured to examine the condition. On the other hand, in order to help prevent future medical management from the standpoint of preventive medicine, the arteriosclerosis test is intended to help prevent the occurrence of events in the brain and annular arteries based on the current evaluation results of arterial blood vessels. Since the deterioration of the arterial blood vessels appears in the viscoelastic characteristics, it is necessary to consider the measurement in a region where the pressure difference PT inside and outside the arterial blood vessel wall where the arterial blood vessel viscoelastic properties are obtained, and in that region, the arterial blood vessels Since dynamic movement of blood vessels is observed, an arterial blood vessel model capable of dealing with such arterial blood vessel characteristics was examined. In the arterial vessel soft region where the arterial vessel viscoelastic characteristics are obtained and the arterial vessel motion is observed and the arterial vessel wall pressure difference PT is low and the elastic deformation is large, the arterial vessel is shown in the PT-A curve shown in FIG. The region I where the arterial vascular elasticity including the region where the tube opens from the closed state to the natural length is soft (for example, the region where the transmural pressure is low until reaching the inflection point of the PT-A curve) is represented by a spring Ge. Dashpot D in which smooth muscle and collagen fibers are connected in parallel with Ge in region II (for example, a region where the transmural pressure is high after reaching the inflection point of the PT-A curve) where blood vessel is subsequently expanded The three-element model represented by the spring G can appropriately represent an arterial vascular rigid region having a high arterial vascular wall internal / external pressure difference PT and a small elastic deformation. The viscosity characteristic is represented by the viscosity η of the dashpot D in which the smooth muscle acts as a main element. The volume strain V (t) with respect to the stress σ in this region is expressed by the following equation (1) when the stress is constant.

V ₀ = σ / G
τ _C = η / G
V (t) = V ₀ (1-e ^{−1 /} τ _C ) (1)

The response of the volume pulse wave to the pulse wave shows a first-order delay characteristic, and τ _C is a time constant called a delay time of the creep characteristic. If it is viscous, it exhibits hysteresis, so the compliance obtained with the present method is incremental compliance. As the spring characteristics of the springs Ge and G decrease (the spring constant increases) due to arteriosclerosis, the time constant of the creep characteristic becomes longer depending on the characteristics of the dashpot D. That is, it is gradually linearized. When the spring property of the spring Ge disappears and the viscosity further increases, the rise of the pulse wave is significantly delayed. Therefore, based on the above three-element arterial vascular model and its deterioration process, the measured vascular compliance is used as an index value that accurately represents the degree of sclerosis of the volume pulse wave, regardless of the severity of arterial vasodilation or arteriosclerosis. Can be used. The present invention has been made based on such knowledge.

That is, the gist of the present invention is that (a) the degree of arterial vascular sclerosis is measured based on the shape of a pulse wave generated in a compression band wound around a part of a living body. (B) a volume pulse wave calculation unit for converting at least a rising section of the pulse wave into a volume pulse wave indicating a volume change on the transmural pressure axis of the arterial blood vessel; and (c) the artery A PA curve generator for generating a PA curve indicating the relationship between the transmural pressure in the blood vessel and the volume or cross-sectional area of the arterial blood vessel, and (d) at least the rising of the volume pulse wave indicating the volume change on the transmural pressure axis A blood vessel compliance calculating unit that calculates a blood vessel compliance waveform indicating an inclination in the section based on the PA curve, and (e) the PA curve of the blood vessel compliance waveform calculated by the blood vessel compliance calculating unit is The PA curve is different from the transmural pressure of the point indicating the maximum compliance of the vascular compliance waveform with respect to the maximum compliance indicating the vascular elasticity characteristic in the region I which is a section until reaching the inflection point. and the index value calculation unit that calculates an index value of vascular compliance is the ratio of a predetermined compliance which corresponds to the transmural pressure value representing the vascular elastic property of the region II is an interval after reaching the inflection point, (f) the And a pulse wave ascending leg time constant calculating unit for calculating a volume strain time constant of the region II in the rising section of the volume pulse wave .

According to the arterial vascular stiffness measuring apparatus of the present invention configured as described above, the volume pulse wave calculation unit causes at least the rising section of the pulse wave generated in the compression band to change in volume on the transmural pressure axis of the arterial blood vessel. The vascular compliance waveform indicating the slope of at least the rising section of the volume pulse wave indicating the volume change on the transmural pressure axis is calculated based on the PA curve by the compliance calculating unit. Corresponding to the transmural pressure value in the region II different from the transmural pressure of the point indicating the maximum compliance of the vascular compliance waveform with respect to the maximum compliance in the region I of the vascular compliance waveform by the value calculation unit An index value of vascular compliance that is a ratio of predetermined compliance is calculated. Therefore, the index value of vascular compliance can be used as an index value that accurately represents the degree of hardening of the arterial blood vessel in a living body, regardless of the severity of arterial vasodilation or arteriosclerosis. Further, since a pulse wave ascending leg time constant calculation unit for calculating the volume strain time constant of the region II in the rising section of the volume pulse wave is included, a time constant representing a volume strain characteristic can also be used as a blood vessel compliance index. it can.

  Here, preferably, the rising section of the pulse wave and the volume pulse wave is a section of the pulse wave and the volume pulse wave that is not affected by the reflected wave in the arterial blood vessel. In this way, since the pulse wave and volume pulse wave are not affected by the reflected wave in the arterial blood vessel, the pulse wave rising period is obtained, so that an accurate blood vessel compliance index that is not affected by the reflected wave is obtained. be able to.

  Preferably, the preset pressure value in the rising section of the volume pulse wave in the region II is larger than the pressure value of the portion where the maximum compliance of the volume pulse wave is calculated. In this way, since the preset pressure value is larger than the pressure value of the part where the maximum compliance of the volume pulse wave is calculated, a predetermined compliance sufficiently lower than the maximum compliance is obtained. Therefore, an accurate blood vessel compliance index with higher accuracy can be obtained.

  Preferably, the two-dimensional display of the vascular compliance index and the time constant of the plethysmographic leg indicates the viscoelastic characteristics of the vascular wall, and objectively detect changes in arteriosclerosis characteristics and abnormal characteristics. I can grasp it.

  Preferably, the plethysmogram calculation unit calculates a cuff compliance indicating a change in pressure in the compression band when a certain volume change is applied to the compression band, and the pressure oscillation in the compression band Based on a certain cuff pulse wave and the cuff compliance, the volume pulse wave representing the volume of the arterial blood vessel that increases per unit length of the arterial blood vessel when the pressure in the arterial blood vessel increases is calculated. In this way, the actual cuff compliance of the compression band is obtained, and the pulse wave is converted into a volume pulse wave based on the actual cuff compliance to obtain an accurate volume pulse wave. A more accurate vascular compliance index can be obtained.

  Preferably, the compression band includes an intermediate inflatable bag, a pressure sensor for detecting a pressure in the intermediate inflatable bag, a pair of upstream inflatable bags disposed downstream of both sides of the intermediate inflatable bag, and a downstream side. In the case of compressing the living body, the pair of the upstream inflating bag, the downstream inflating bag, and the intermediate inflating bag are pressurized to increase the pressure of the living body. Since the pulse wave is obtained from the intermediate inflatable bag, the measurement value shifts due to a decrease in the compression pressure at the side edge of the compression band. (Short cuff effect) is preferably prevented.

Preferably, a blood pressure measurement unit that measures the arterial pressure and the pulse wave of the compression band from time series data of the pulse wave generated in the compression band is included. In this case, a blood pressure value can also be obtained simultaneously using an arterial vascular stiffness measuring apparatus . Also, preferably, the pressure value of the pulse wave rising phase time constant calculating section of the region II is a large value to the extent that the reflected wave of the artery does not show a discontinuity in the calculation range. In this way, a highly accurate time constant can be obtained.

  Preferably, the plethysmogram calculation unit adds a predetermined volume of gas having a size corresponding to the pulsation of the arterial blood vessel from the constant plethysmogram generator into the intermediate inflation bag. When the cuff sensitivity indicating the change in pressure in the cuff is calculated, the volume value of the constant volume of gas added to the intermediate expansion bag, and when the constant volume of gas is added to the intermediate expansion bag The relationship with the pressure increase value in the intermediate expansion bag detected by the second pressure sensor is obtained in advance. In this way, the cuff compliance of the intermediate expansion bag is, for example, a constant volume of gas from the constant volume pulse wave generator in the intermediate expansion bag in response to a preset constant cycle, pulse, or pressure change value. Each time it is added, it is obtained sequentially.

1 is a perspective view showing an automatic blood pressure measuring device that also functions as an arterial vascular stiffness measuring device to which the present invention is applied. FIG. It is a block diagram explaining the principal part of a structure of the automatic blood pressure measuring device of FIG. It is a figure which cuts off the outer side of the compression band with which the automatic blood pressure measuring device of FIG. It is a figure which cuts out some upstream side expansion bags, intermediate | middle expansion bags, and downstream expansion bags accommodated in the compression belt | band | zone shown in FIG. It is sectional drawing explaining the structure of the upstream expansion bag of FIG. 4, an intermediate | middle expansion bag, and a downstream expansion bag, Comprising: It is the VV view of FIG. It is a functional block diagram explaining the principal part of the control function of the electronic control apparatus of FIG. It is a time chart explaining the principal part of the control action of the electronic controller of FIG. (a) is a figure explaining an actual PA curve, (b) is a figure explaining the PA curve which the PA curve production | generation part of FIG. 7 produces | generates. It is a figure which shows the volume pulse wave on the time-axis converted from the pulse wave in the volume pulse wave calculation part of FIG. It is a figure which shows the volume pulse wave on the through-wall pressure axis | shaft converted from the volume pulse wave on a time axis in the volume pulse wave calculation part of FIG. It is a figure which shows the blood vessel compliance waveform calculated based on the volume pulse wave on the transmural pressure axis obtained from the healthy person in the blood vessel compliance calculation part of FIG. It is a figure which shows the blood vessel compliance waveform calculated based on the volume pulse wave on the transmural pressure axis obtained from the arteriosclerosis patient in the blood vessel compliance calculation part of FIG. It is a characteristic view which the blood vessel volume compliance of the area | region II with respect to age shows. It is a characteristic view which the blood vessel compliance index value with respect to age shows. FIG. 6 is a characteristic diagram showing vascular dilation and vascular compliance index values in region I. It is a characteristic figure which the pulse wave rise leg volume strain time constant to age shows. It is a figure which shows the two-dimensional display of a pulse wave rise volume strain time constant and the blood vessel compliance index value. It is a flowchart explaining the principal part of the control action of the electronic controller of FIG. It is a flowchart explaining the principal part of the control action of the electronic controller of FIG. 2, Comprising: It is a flowchart explaining in detail the data post-analysis routine of FIG. Three-element model of arterial blood vessels PT-A curve

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a perspective view for explaining the overall configuration of an automatic blood pressure measuring apparatus 10 that also functions as an arterial vascular sclerosis measuring apparatus according to an embodiment of the present invention. The automatic blood pressure measurement device 10 includes a compression band 12 wound around a part of a living body, for example, the upper arm 11, a plurality of ECG electrodes 14, and an input keyboard 17 having a plurality of keys provided on the upper surface of the main body 8. A blood pressure of a living body including an image display 18 provided on the front surface of the main body 8 and an output printer 19 provided on a side surface of the main body 8, around which the compression band 12 is wound and a plurality of ECG electrodes 14 are mounted. And the blood pressure measurement value BP is displayed on the image display 18, while the arteriosclerosis degree ACI of the living body is calculated and displayed on the image display 18 as the evaluation value of the arteriosclerosis degree or arteriosclerosis degree of the living body. These display values are output from the output printer 19 as necessary.

  FIG. 2 is a block diagram illustrating a main part of the configuration of the automatic blood pressure measurement device 10. A pulse wave detection compression band (cuff) 12 wrapped around a living body limb, for example, the upper arm portion 11, which is a pressed portion, includes an upstream expansion bag 22, an intermediate expansion bag 24, and a downstream expansion bag 26. FIG. 3 shows the outer peripheral surface of the compression band 12 with a part thereof cut away. As shown in FIG. 3, the compression band 12 includes an outer circumferential side nonwoven fabric 20 a made of a synthetic resin fiber whose back surface is laminated with a synthetic resin such as PVC, and a belt-shaped outer bag 20 composed of an inner circumferential side nonwoven fabric similar to the outer circumferential side nonwoven fabric 20 a. The outer bag 20 is sequentially accommodated in the width direction, and includes an upstream expansion bag 22, an intermediate expansion bag 24, and a downstream expansion bag 26 made of a flexible sheet such as a soft polyvinyl chloride sheet. A raised pile (not shown) attached to the end of the inner peripheral nonwoven fabric is detachably attached to the surface fastener 28 attached to the end of the side nonwoven fabric 20a, so that the upper arm 11 is detachably attached. It has become. The upstream expansion bag 22, the intermediate expansion bag 24, and the downstream expansion bag 26 constitute independent air chambers, and include pipe connection connectors 32, 34, and 36 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.

  FIG. 4 is a view in which a part of the upstream expansion bag 22, the intermediate expansion bag 24, and the downstream expansion bag 26 provided in the compression band 12 is cut away, and FIG. 5 illustrates them in the width direction. FIG. 5 is a cross-sectional view taken along the line VV in FIG. 4. The upstream expansion bag 22, the intermediate expansion bag 24, and the downstream expansion bag 26 each have a longitudinal shape, and the upstream expansion bag 22 and the downstream expansion bag 26 are disposed adjacent to both sides of the intermediate expansion bag 24. Has been. The intermediate inflation bag 24 is for detecting a pulse wave PW generated from the arterial blood vessel 16 and is sandwiched between the upstream inflation bag 22 and the downstream inflation bag 26 in the width direction of the compression band 12. It is arranged at the center of the.

  The intermediate inflatable bag 24 has side edges of a so-called gusset structure on both sides. That is, at both ends in the longitudinal direction of the upper arm portion 11 of the intermediate inflatable bag 24, a pair of folding grooves 24f and 24f made of a flexible sheet folded in a direction approaching each other so as to become closer to each other are formed. Each is formed. Then, 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 24f so as to be arranged. It has become. As a result, both end portions of the intermediate expansion bag 24 and the upstream side expansion bag 22 and the adjacent side end portions 22a and 26a of the downstream side expansion bag 26 adjacent to the intermediate expansion bag 24 are overlapped with each other, that is, overlap. Because of the structure, when the upstream expansion bag 22, the intermediate expansion bag 24, and the downstream expansion bag 26 press the upper arm portion 11 with the same pressure, a uniform pressure distribution can be obtained even near the boundary between them. In this case, the upstream inflation bag 22 and the downstream inflation bag 26 function exclusively as a main inflation bag for compressing the upper arm portion 11, and the intermediate inflation bag 24 exclusively detects a pulse wave generated from the arterial blood vessel 16. It functions as a pulse wave detector.

  The upstream expansion bag 22 and the downstream expansion bag 26 also include end portions 22b and 26b opposite to the intermediate expansion bag 24 at a side edge portion of a so-called gusset structure. 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. Thereby, since the compression pressure with respect to the upper arm part 11 is obtained similarly to other parts also in the end parts 22b and 26b of the upstream expansion bag 22 and the downstream expansion bag 26, the effective compression width in the width direction of the compression band 12 is increased. It becomes equivalent to the width dimension. The width direction of the compression band 12 is, for example, about 12 cm. 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 of the compression bands 12 is substantially The width dimension is about 4 cm, and the substantial distance L13 between the upstream expansion bag 22 and the downstream expansion bag 26 is, for example, about 8 cm. In order to sufficiently generate a compression function even with such a narrow width dimension, both end portions 24a and 24b of the intermediate expansion bag 24, adjacent side end portions 22a and 26a of the upstream expansion bag 22 and the downstream expansion bag 26, and Are overlapped with each other, 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 have side edges of a so-called gusset structure. Has been.

  Ends 22a and 26a on the intermediate expansion bag 24 side of the upstream expansion bag 22 and the downstream expansion bag 26, and the inner wall surfaces of the pair of folding grooves 24f and 24f into which they are inserted, that is, the opposite groove side surfaces Between them, there are interposed longitudinal shielding members 42 having rigidity anisotropy in which the bending rigidity in the width direction of the compression band 12 is higher than the bending rigidity in the longitudinal direction of the compression band 12. In this embodiment, as shown in FIGS. 4 and 5, the outer peripheral side gap among the gaps between the end portion 22 a of the upstream inflatable bag 22 and the folding groove 24 f into which it is inserted, and the downstream side Longitudinal shielding members 42 are interposed in gaps on the outer peripheral side of the gaps between the end portions 26a of the side expansion bags 26 and the folding grooves 24f into which the side expansion bags 26 are inserted. May also be interposed. Since the outer circumferential side gap has a larger shielding effect than the inner circumferential side gap, it is sufficient to be provided at least in the outer circumferential side gap.

  The longitudinal shielding member 42 is formed in the circumferential direction of the upper arm portion 11 in a state in which a plurality of resin-made flexible hollow tubes 44 parallel to the longitudinal direction of the upper arm portion 11, that is, the width direction of the compression band 12, are parallel to each other. That is, while being arranged continuously in the longitudinal direction of the compression band 12, the flexible hollow tubes 44 are directly formed by molding or bonding, or indirectly through another member such as a flexible sheet such as an adhesive tape. Are connected to each other. The longitudinal 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. It has been.

  Returning to FIG. 2, in the automatic blood pressure measurement device 10, the electric pump 50, the quick exhaust valve 52, and the exhaust control valve 54 are connected to the compression band 12 via the main pipe 56. From the main pipe 56, a first branch pipe 58 provided in series with a first on-off valve E1 for directly opening and closing between the electric pump 50 and the upstream side expansion bag 22, and connected to the upstream side expansion bag 22, A second branch pipe 60 provided in series with a second on-off valve E2 and a fourth on-off valve E4 for directly opening and closing between the electric pump 50 and the intermediate expansion bag 24, and connected to the upstream expansion bag 22, an electric pump A third branch pipe 62 that is provided in series with a third on-off valve E3 for directly opening and closing between 50 and the downstream expansion bag 26 is connected to the downstream expansion bag 26. A pipe line between the second on-off valve E2 and the fourth on-off valve E4 of the second branch pipe 60 is connected to the third branch pipe 62 via a volume pulse generator (EPG: volume pulse wave generator) 64. ing. The fourth on-off valve E4 is a three-way valve that connects the volume pulse generator 64 to one or the other of the reference capacity tank 66 and the intermediate expansion bag 24. A main pressure sensor T4 for detecting the pressure in the main pipe 56 or an expansion bag connected to the main pipe 56 is connected to the main pipe 56, and a first pressure sensor T1 for detecting the pressure of the upstream side expansion bag 22. Is connected to the upstream expansion bag 22, and a second pressure sensor T2 for detecting the pressure of the intermediate expansion bag 24 is connected to the intermediate expansion bag 24, and a third pressure for detecting the pressure of the downstream expansion bag 26 The sensor T3 is connected to the downstream expansion bag 26.

  Based on the output signals of the main pressure sensor T4, the first pressure sensor T1, the second pressure sensor T2, the third pressure sensor T3 and the signal from the ECG electrode 14, the electrocardiographic induction signal output from the electrocardiogram circuit unit 71 is It is supplied to the electronic control unit 70 via the A / D converter 72. The electronic control unit 70 is a so-called microcomputer including a CPU, a RAM, a ROM, an I / O port, and the like (not shown). The CPU uses an input signal according to a program stored in the ROM in advance using the storage function of the RAM. Through the pump drive circuit 73, the exhaust valve drive circuit 74, and the solenoid valve drive circuit 75, the electric pump 50, the quick exhaust valve 52, the exhaust control valve 54, the first on-off valve E1, the first Measurement data generated from the arterial blood vessel 16 of the upper arm portion 11 is collected by controlling the second on-off valve E2, the third on-off valve E3, and the volume pulse generator 64, and the blood pressure value BP of the living body based on the measurement data , Arterial vascular stiffness (vascular compliance) ACI, pulse wave velocity PWV is calculated, and the measured value which is the calculation result is displayed on the image display 18 Display.

  FIG. 6 is a functional block diagram for explaining the main part of the control function of the electronic control unit 70. In FIG. 6, the cuff pressure control unit 100 includes an electric electric pump 50, a quick exhaust valve 52, an exhaust control valve 54, a first on-off valve E1, a second on-off valve E2, a third on-off valve E3, and volume pulse generation. By controlling the vessel 64, as shown in FIG. 7, the pressure of the upstream expansion bag 22, the intermediate expansion bag 24 and the downstream expansion bag 26 of the compression band 12, that is, the cuff pressure Pcuff which is the compression pressure to the living body is reduced. Control.

  The blood pressure measurement unit 102 is a process of gradually lowering the compression pressure of the compression band (cuff) 12 wound around the upper arm portion 11 from a pressure higher than the maximum blood pressure value, that is, the interval t2 to t3 in FIG. 7, and t8 to t9. In the section, the cuff pulse wave that is the pressure vibration component in the intermediate expansion bag 24 of the compression band 12 is sequentially detected, and the cuff when the maximum difference value between the cuff pulse waves is generated, for example, based on the series of changes in the cuff pulse wave. The maximum blood pressure value SBPo and the minimum blood pressure value DBPo, which are reference blood pressure values of the living body, are measured using an oscillometric method for detecting pressure. For example, the first (preliminary or primary) blood pressure measurement is performed in the period t2 to t3, and the second (secondary) blood pressure measurement is performed in the period t8 to t9.

  The pulse wave velocity measuring unit 104 is a pulse wave velocity in the arterial blood vessel 16 of the upper arm 11, for example, a pulse wave from the aortic origin to the upper arm 11 during the period t 5 to t 6 between the two blood pressure measurement intervals. The propagation speed hbPWV is determined for each beat from the time difference (propagation time) PWT and distance L between the cuff pulse wave and the electrocardiogram R wave obtained by the intermediate expansion bag 24 of the compression band 12 wound around the upper arm portion 11. The pulse wave propagation velocity hbPWV (= L / PWT) is sequentially measured. The compression band 12 at this time is maintained at a pressure Ppwv set to about 50 mmHg lower than the minimum blood pressure value DBP where the influence of the cuff is small for the propagation velocity measurement.

  The storage unit 106 stores the cuff pulse wave, which is a pressure vibration component in the intermediate inflatable bag 24, during the blood pressure measurement period, together with the cuff pressure (compression pressure) Pcuff when it is detected. In particular, in the period from t8 to t17 in which the secondary measurement of blood pressure is performed, stepwise so as to include a plurality of cuff pressure maintaining sections that maintain the cuff pressure Pcuff at a plurality of types of pressures, for example, P1, P2,... Pj, Pj + 1. The cuff pressure Pcuff is changed, and a plurality of cuff pulse waves without distortion are detected in the cuff pressure maintaining section, and a plurality of cuff pulse waves are detected in one cuff pressure maintaining section. At the same time, one cuff pulse wave or a cuff pulse wave obtained by averaging the plurality of cuff pulse waves is stored. The stored cuff pulse wave includes not only the cuff pulse waves D1, D2,... Dj, Dj + 1D obtained when the cuff pressure Pcuff is P1, P2,... Pj, Pj + 1, but also the cuff pressure Pcuff. The cuff pulse wave MAP1 collected when the cuff pressure is about 10 mmHg higher than the minimum blood pressure DBP, that is, the pressure MAP1press when the arterial blood vessel 16 starts to open is included.

  The PA curve generation unit 108 shows a PA curve indicating the relationship between the transmural pressure PT (mmHg) in the arterial blood vessel 16 of the upper arm 11 of the living body and the arterial blood vessel 16 cross-sectional area A (cm 2), for example, in FIG. Generate as shown. The transmural pressure PT is the difference between the arterial pressure inside the blood vessel and the blood vessel wall external pressure, and takes the cuff pressure Pcuff as the blood vessel wall external pressure. PT is defined by the following equation (2) with the reference point of arterial pressure as the diastolic blood pressure DBP when no cuff pressure is applied.

PT = DBP-Pcuff (2)

  In FIG. 8, the buckling region is a region where the arterial blood vessel 16 is buckled and deformed by an external pressure even in a normal living body, and the pressure value Pb between the buckling region and the vascular soft region having a large elastic deformation is For example, the pressure value Ps between the vascular soft region (soft region) and the vascular rigid region (hard region) with small elastic deformation is about 60 mmHg, for example, about 10 mmHg. In this PA curve, point Pb is a boundary point of the pipe rule, and the transmural pressure PT of the arterial blood vessel starts to act as a tension in the circumferential direction with respect to the arterial blood vessel wall. Therefore, it is regarded as a point indicating a circle corresponding to the natural length. FIG. 8A shows an example of a PA curve in which blood vessels expand over time. FIG. 8B schematically shows a state in which the extensibility of the arterial blood vessel is lost due to arteriosclerosis and the state is shifted to a solid line state from the one-dot chain line state in the PA curve. Region I indicates the range of flexible transmural pressure PT until the inflection point of the PA curve indicated by the solid line in which the extensibility of the artery is reduced, and region II is indicated by the solid line. Shows the range of the through-wall pressure PT after the PA curve exceeds the inflection point. That is, the region I indicates a region where the arterial vascular elasticity is soft, and the region II indicates a region where the arterial blood vessel subsequently expands, that is, the arterial blood vessel becomes hard.

  In the above PA curve, the buckling region is unstable and exhibits hysteresis. Therefore, an experiment was performed as an incremental PA curve from the rising characteristic of the volume pulse wave MAP1pvr collected when the pressure of the arterial blood vessel was increased MAP1press in the process of decreasing the compression pressure. Ask for. Note that the PA curve based on the pipe law, that is, the PA curve applied between Pb and Ps, is stored in advance and is represented by the following equation (3).

A = (Ab / b) ln (PT− (Pb−a)) + dD (3)
However, a is a shift parameter and b is a scale parameter.

In the volume pulse wave calculation unit 110, first, the cuff pulse wave stored in the storage unit 106 is a waveform shown in the two-dimensional coordinates of the pressure value axis (mmHg) and the time axis (msec). (Cross sectional area) Converted into volume pulse wave shown in two-dimensional coordinates of axis (cm ³ = cc) and time axis. For example, the fixed volume C (cc) of the constant volume C (cc) from the volume pulse generator 64 under the compression pressure by the intermediate expansion bag 24, that is, under each of the first pressure P1, the second pressure P2, the jth pressure Pj, the j1 pressure Pj1, and the pressure MAP1press. The pressure rise value ΔPcuff (mmHg) in the cuff pulse wave signal superimposed with the pressure pulse Pp generated when the pulse is applied is detected, and the cuff compliance Se (cm ³ = mmHg), that is, from the equation shown in the following equation (4), By calculating Se1, Se2, ... Sej, Sej1 and multiplying the cuff compliance Se by the pressure value in the vertical direction of the cuff pulse wave, it is converted to a volume pulse wave whose unit is volume (cross-sectional area) To do. That is, the vertical axis of the cuff pulse wave is converted from the pressure value axis (mmHg) to the volume (cross-sectional area) axis (cm ³ ). FIG. 9 shows the rising portion of the volume pulse wave MAP1pvr obtained under the pressure MAP1press in contrast to the rising portion of the volume pulse wave D2pvr obtained under the second pressure P2 on the common time axis. .

  Se = ΔPcuff / C (4)

  The plethysmogram calculation unit 110 calculates the plethysmogram shown in the two-dimensional coordinates of the time axis that is the horizontal axis and the volume axis that is the vertical axis, and the PA curve calculated by the PA curve generation unit 108. Is used to convert the transpulmonary pressure into a volume pulse wave expressed in two-dimensional coordinates of the PT axis (mmHg) and the volume (cross-sectional area) axis. That is, in the PA curve, the value of the point corresponding to the magnitude (volume value) of the transpulmonary pressure PT axis direction of the volume pulse wave whose horizontal axis is the time axis, and the horizontal axis is the transmural pressure PT axis (mmHg) The volume pulse wave in which the horizontal axis is converted from the time axis to the through-wall pressure PT axis (mmHg) is generated by making the correspondence so that the magnitude of the volume pulse wave is as follows. Conversion of D2pvr from the time axis to the pressure axis, and application to MAP1pvr assumes that the viscosity η of the blood vessel wall in equation (1) can be ignored.

  When the effect of viscosity is large and the delay time τc is extended so that the amplitude of the pulse wave is small without reaching the equilibrium state, the compliance is apparently small, and the cross-sectional area of the blood vessel lumen of the present method is also small. Since V / V0 is derived simultaneously with τc, the scope of application of this method can be determined. Further, when V / V0 is small due to the extension of τc, it is possible to predict that arteriosclerosis has progressed extremely because attenuation of vascular elasticity G and increase in vascular viscosity η are expected. FIG. 10 shows rising portions of the volume pulse wave MAP1pvr and the volume pulse wave D2pvr in which the horizontal axis is converted from the time axis to the through-wall pressure PT axis (mmHg). FIG. 8B illustrates the volume pulse wave MAP1pvr on the time axis obtained under the pressure MAP1press and the volume pulse wave MAP1pvr on the through-wall pressure PT axis converted therefrom.

  The vascular compliance calculation unit 112 is configured so that the plethysmogram MAP1pvr on the transmural pressure PT axis calculated by the plethysmogram calculation unit 110 has an inclination (inclination ΔA / ΔPT) of each part according to each transmural pressure PT. Since the compliance K of the arterial blood vessel wall is shown, the blood vessel compliance curve shown in FIG. 11 or FIG. 12 is calculated by differentiating at least the rising section of the volume pulse wave shown in FIG. A maximum compliance value Kmax, which is a value, is calculated. Further, in FIGS. 11 and 12, the through-wall pressure PT value corresponding to the maximum compliance value Kmax is about 5 mmHg. Therefore, a predetermined constant through-wall pressure PT value in a soft region larger than that by a predetermined value, for example, The compliance K40 corresponding to 40 mmHg is calculated by determining the volume corresponding to the through-wall pressure PT value of 40 mmHg of the differential waveform. It is desirable that Kmax be determined within a range not affected by the reflected wave, that is, within a range where reflection from the arterial blood vessel bifurcation downstream of the compression band 12 does not overlap. In FIG. 10, for example, in order to determine the rising section, the through-wall pressure PT value is influenced by the reflected wave in a region larger than a predetermined pressure value PT1 corresponding to the maximum slope point or inflection point of the PA curve, for example. Therefore, the region where the through-wall pressure PT value is lower than PT1 is used to determine the maximum compliance value Kmax and the compliance K40.

  The index value calculation unit 114 calculates a compliance index value ACI that is a ratio or ratio thereof based on the maximum compliance value Kmax and the compliance K40 calculated by the blood vessel compliance calculation unit 112. The compliance index value ACI of this embodiment is defined as the ratio of the compliance K40 to the maximum compliance value Kmax (K40 / Kmax).

  13 is a characteristic diagram showing the blood vessel volume compliance in the region II with respect to age, FIG. 14 is a characteristic diagram showing the blood vessel compliance index value with respect to the age, and FIG. 15 is a blood vessel compliance index value in the region I with vascular dilation. FIG. 16 is a characteristic diagram showing a pulse wave rising leg volume strain time constant with respect to age.

  18 and 19 show flowcharts for explaining the main part of the control operation of the electronic control unit 70, respectively. In FIG. 18, when a power switch (not shown) is turned on, the initial state shown at t0 in FIG. 7 is set, and then in step S1 (hereinafter, step is omitted), patient data input by the operator, such as gender, age, etc. First name, second on-off valve E2, second on-off valve E3, third on-off valve E3, and quick exhaust valve 52 are normally open valves, so that they are not activated, that is, open (open) state. Since the exhaust control valve 54 is a normally closed valve, it is in a non-operating state, that is, a closed state, and the volume pulse generator 64 and the electric pump 50 are in a non-operating state. Next, when a startup operation device (not shown) is operated to start the measurement operation of the automatic blood pressure measurement device 10 that also functions as an arterial blood vessel display device, first, in step S2 of FIG. 18 shown at times t1 to t3 of FIG. A preliminary blood pressure measurement routine or a blood pressure measurement 1 routine is executed. This S2 corresponds to the cuff pressure control unit 100 and the blood pressure measurement unit 102.

  In the first blood pressure measurement routine, first, at time t1 in FIG. 7, the electric pump 50 is started, and the upstream expansion bag 22, the intermediate expansion bag 24, which are in communication with the compressed air pumped from the electric pump 50, and The pressure of the downstream expansion bag 26 is rapidly increased, and the compression of the upper arm portion 11 by the entire compression band 12 is started. When the pressure detected by the main pressure sensor T0, that is, the compression pressure Pe by the compression band 12, reaches a pressure increase target pressure Pmax set in advance to a value sufficiently higher than the maximum blood pressure value of the living body, the operation of the electric pump 50 is stopped. In response to this, the exhaust control valve 54 is operated so that the compression pressure by the compression band 12 decreases at a constant speed, and the slow exhaust is started. Time t2 in FIG. 7 shows this state. In this slow exhaust process, the cuff pressure signal indicating the compression pressure (static pressure) by the compression band 12 is discriminated from the pressure signal output from the second pressure sensor T2 by low-pass filter processing, and several A pulse wave signal is discriminated by performing a band pass filter process for discriminating a signal in a wavelength band of 100 Hz to several tens of Hz. Then, according to the oscillometric blood pressure value determination algorithm executed every time the pulse wave signal is generated, the systolic blood pressure value SBP (mmHg) and the minimum blood pressure value DBP (mmHg ) And stored, and at the same time that the minimum blood pressure value DBP is determined, the quick exhaust valve 52 is opened, and in response, the exhaust control valve 54 is opened until it reaches its maximum opening, and S2 in FIG. Is terminated. Time t3 in FIG. 7 shows this state.

  For example, the oscillometric blood pressure value determination algorithm uses the pressure indicated by the pressure signal corresponding to the maximum peak point of the differential waveform of the envelope when the envelope (envelope) connecting the amplitude values of the pulse wave signal rises sharply. When the envelope value (envelope) connecting the amplitude value of the pulse wave signal suddenly decreases after the amplitude value of the pulse wave signal reaches the maximum value of the line (envelope) after determining the value SBP value (mmHg) That is, the pressure indicated by the pressure signal corresponding to the minimum peak point of the differential waveform of the envelope is determined as the minimum blood pressure value DBP. The pressure signal output from the first pressure sensor T1 is discriminated by the band pass filter process, and the pulse wave signal discriminated by the band pass filter process, and the pressure signal output from the second pressure sensor T2 is discriminated by the band pass filter process. The pulse wave signal and the pressure signal output from the third pressure sensor T3 are subjected to band pass filter processing, and the pulse wave signal and the pressure signal output from the main pressure sensor T0 are subjected to band pass filter processing. There is a difference in amplitude between the four pulse wave signals of the discriminated pulse wave signal, and the pulse wave signal output from the second pressure sensor T2 that detects the pressure in the intermediate inflation bag 24 is the arterial blood vessel 16. It reflects the pulsation of the most accurately.

  Next, the pulse wave velocity measurement routine of S3 in FIG. 18 is executed in the section shown at times t4 to t6 in FIG. This S3 corresponds to the cuff pressure control unit 100 and the pulse wave velocity measurement unit 104. In S3, first, the quick exhaust valve 52 and the exhaust control valve 54 are closed and the electric pump 50 is started. Next, when the pressures of the upstream expansion bag 22, the intermediate expansion bag 24, and the downstream expansion bag 26 reach a pulse wave detection pressure Ppwv set in advance to a value in the vicinity of the minimum blood pressure value DBP or a value lower than that, for example, 50 mmHg. The first on-off valve E1, the second on-off valve E2, and the third on-off valve E3 are closed, and the upstream expansion bag 22, the intermediate expansion bag 24, and the downstream expansion bag 26 are maintained at the pulse wave detection pressure independently of each other. Is done. This state is shown at time t5 in FIG. In this state, the pressure signals output from the first pressure sensor T1 and the third pressure sensor T3 are subjected to bandpass filter processing, thereby indicating pulse waves detected by the upstream expansion bag 22 and the downstream expansion bag 26. The pulse wave signals are discriminated, and the phase difference Δt1 (pulse wave propagation time sec) of these pulse wave signals and a predetermined center distance L13 (m 13) between the upstream expansion bag 22 and the downstream expansion bag 26 of about 90 mm, for example. ) And the local pulse wave velocity bbPWV (m / sec) is calculated from the following equation (5). Such calculation of the local pulse wave velocity bbPWV is repeatedly executed every time a pulse wave is generated until time t6 is reached, and when it reaches, an average value of the local pulse wave velocity bbPWV obtained so far is calculated and stored. Is done. In addition, a time difference Δt2 (pulse wave propagation time sec) between the generation time of the heart sound or ECG R wave detected by a heart sound microphone (not shown) and the rising time of the cuff pulse wave detected by the intermediate inflatable bag 24 is previously determined between the two. Based on the determined distance L2 (m), the pulse wave velocity hbPWV (m / sec) is calculated from the following equation (6) at a predetermined pressure lower than the minimum blood pressure DBP where the influence of cuff is small, for example, 50 mmHg. Memorized.

bbPWV = L1 / Δt1 (5)
hbPWV = L2 / Δt2 (6)

  Next, in FIG. 18, in S4 corresponding to the cuff pressure control unit 100, the blood pressure measurement unit 102, and the storage unit 106, the second blood pressure measurement / pulse wave collection routine is executed in the section shown at time t7 to t9 in FIG. The In S4, as in the first blood pressure measurement routine, first, at time t7, the electric pump 50 is activated, and the upstream expansion bag 22, the intermediate expansion bag 24, And the pressure of the downstream expansion bag 26 is rapidly increased, and the compression of the upper arm portion 11 by the entire compression band 12 is started. The pressure detected by the main pressure sensor T0, that is, the compression pressure Pe generated by the compression band 12, is set to a pressure increase target pressure that is set in advance to a value higher than the maximum blood pressure SBP of the living body, which is the previous measurement value by the first blood pressure measurement routine. When Pmax is reached, the operation of the electric pump 50 is stopped, and in response to this, the exhaust control valve 54 is operated so that the compression pressure Pe by the compression band 12 is lowered at a constant speed, and per unit time or unit Slow exhaust at a constant speed per pulse wave is started. Time t8 in FIG. 7 shows this state. In the slow exhaust process after the time t8, when the pressure detected by the main pressure sensor T4, that is, the compression pressure Pe by the compression band 12 reaches the preset first maintenance pressure P1 (time t9), it responds to it. The on-off valves E1, E2, E3, and the exhaust control valve 54 are closed for a certain cuff pressure maintaining time, and the pressures of the upstream expansion bag 22, the intermediate expansion bag 24, and the downstream expansion bag 26 are changed to the first maintenance pressure P1. Until time t10. In the first pressure maintaining section between times t9 and t10, air having a constant volume C of about 0.2 cc, for example, from the volume pulse generator 64 is synchronized with the generation of the pulse wave and at a timing corresponding to the bottom of the pulse wave. Is pulsed into the intermediate inflatable bag 24 in a width of 100 ms to 150 ms, and the signal output from the second pressure sensor T2 is subjected to band pass filtering, so that it is added from the volume pulse generator 64. A pressure pulse Pp1 generated in response to the volume pulse is obtained and stored. This pressure pulse Pp is used to calculate the cuff compliance Se at the first maintenance pressure P1 obtained from the equation (4). In the first pressure maintaining section, a plurality of cuff pulse waves may be collected in a constant pressure maintaining state, the cuff pulse waves may be stored, or the average cuff pulse wave may be stored in the first pressure maintaining section. It may be stored together with the pressure P1. An average pressure pulse of a plurality of pressure pulses Pp generated when a plurality of volume pulses are input may be stored. When the time t10 is reached, the first pressure maintaining section is terminated and the first on-off valve E1, the second on-off valve E2, and the third on-off valve E3 are opened again, and at the same time, the exhaust control valve 54 gradually increases. Fast step-down is resumed.

When the compression pressure Pe by the compression band 12 reaches the preset second pressure P2 (time t11), the second pressure maintenance section is formed until the time t12 is reached, like the first pressure maintenance section, and the compression is performed. When the pressure Pe reaches the preset jth pressure Pj (time t13), the jth pressure maintaining section is formed until the time t14 is reached, and when the compression pressure Pe reaches the preset j1 pressure Pj1 ( At time t15), similarly to the above, the j1th pressure maintaining section is formed until time t16 is reached. In the second pressure maintenance section, the maintenance pressure, the jth pressure maintenance section, and the j1 pressure maintenance section, the detected cuff pulse wave is the second maintenance pressure P2 and the jth maintenance, as in the first pressure maintenance section. The pressure Pj is stored together with the j1 maintenance pressure Pj1, and the cuff compliance Se (cm ³ / cm) of the intermediate expansion bag 24 at the first maintenance pressure P1, the second maintenance pressure P2, the jth maintenance pressure Pj, and the j1 maintenance pressure Pj1. mmHg), that is, pressure pulses Pp1, Pp2,... Ppj, Ppj1 used for calculating Se1, Se2,... Sej, Sej1 from the equation (4) are stored. The cuff compliances Se1, Se2, Sej, and Sej1 represent the sensitivity indicating the ratio of the pressure change with respect to the volume change of the intermediate expansion bag 24. When the cuff compliance Se is obtained in this manner, the vertical axis, that is, the amplitude of the pulse wave detected by the second pressure sensor T2 from the intermediate expansion bag 24 can be converted into a volume. That is, a volume pulse wave in which the vertical axis is converted from the pressure axis (mmHg) to the volume axis (cm ³ or cross-sectional area cm ² ) can be obtained from the detected cuff pulse wave, that is, the pulse wave.

In S5, a data analysis routine for calculating the index value ACI of the blood vessel compliance K of the living body from the pulse wave stored as described above is executed according to the flowchart of FIG. 19, in S51 corresponding to the PA curve generation unit 108, a PA curve indicating the relationship between the transmural pressure PT (mmHg) in the arterial blood vessel 16 of the upper arm 11 of the living body and the arterial blood vessel 16 cross-sectional area A (cm ² ). Is generated, for example, as shown in FIG. In FIG. 8B, the pressure value Pb between the buckling region and the vascular soft region having a large elastic deformation is, for example, about 10 mmHg, the vascular soft region (soft region) and the vascular hard region (hard region) having a small elastic deformation. The pressure value Ps between is set to a value of about 60 mmHg, for example. In the PA curve, the pipe law equation (3) is applied to a region where the through-wall pressure PT is larger than the pressure value Pb (PT> Pb). Since the buckling region exhibits hysteresis in the unstable region, the buckling region is experimentally obtained as an incremental PA curve from the rising characteristics of the volume pulse wave MAP1pvr collected when the pressure of the arterial blood vessel opens MAP1press in the process of decreasing the compression pressure.

Next, in S52 corresponding to the volume pulse wave calculation unit 110, first, the cuff pulse wave stored in the storage unit 106 is shown in the two-dimensional coordinates of the time axis (msec) and the pressure value axis (mmHg). Since it is a pulse wave waveform, it is converted into a volume pulse wave shown in two-dimensional coordinates of a time axis and a volume (cross-sectional area) axis (cm ³ ). That is, a constant volume C (cc) is generated from the volume pulse generator 64 under the compression pressure by the intermediate expansion bag 24, that is, under the first pressure P1, the second pressure P2, the jth pressure Pj, the j1 pressure Pj1, and the pressure MAP1press. The pressure rise value ΔPcuff (mmHg) in the cuff pulse wave signal superimposed with the pressure pulse Pp generated when the pulse is applied is detected, and the cuff compliances Se1, Se2, Sej, Sej1 are obtained from the formula shown in the formula (4), respectively. The cuff compliances Se1, Se2, Sej, and Sej1 are multiplied by the vertical axis of the cuff pulse wave, and converted into a volume pulse wave whose unit is a volume (cross-sectional area). That is, the cuff pulse wave whose vertical axis is the pressure value axis (mmHg) is converted into the volume pulse wave whose vertical axis is the volume (cm ³ or cross-sectional area cm ² ) axis. FIG. 9 shows rising portions of the volume pulse waves D2pvr and MAP1pvr having the same time axis. In S53 corresponding to the volume pulse wave calculation unit 110, the volume V0 in the equilibrium state of Equation (1) and the volume strain time constant τc of the pulse wave rising leg in Equation (1) are calculated from the volume-time characteristics of D2pvr in FIG. To do.

  Further, in S54 corresponding to the volume pulse wave calculation unit 110, the volume pulse shown in the two-dimensional coordinates of the volume axis and the time axis using the drift PA curve calculated in S51 (PA curve generation unit 108). The wave is converted to a volume pulse wave shown in the two-dimensional coordinates of the volume axis and the transmural pressure axis. That is, for example, in the PA curve shown in FIG. 8, the volume value at the point corresponding to the magnitude (volume value) of the volume pulse wave in the PT axis direction of the volume pulse wave whose horizontal axis is the time axis, Corresponding to the magnitude of the volume pulse wave as the pressure PT axis (mmHg), the rise of the volume pulse wave shown in FIG. 10 with the horizontal axis converted from the time axis to the transmural pressure PT axis (mmHg) Generate part. In FIG. 10, the rising portion of the volume pulse wave MAP1pvr on the transmural pressure PT axis converted from the volume pulse wave MAP1pv on the time axis is on the transmural pressure PT axis converted from the volume pulse wave D2pv on the time axis. This is illustrated in comparison with the rising portion of the volume pulse wave D2pvr.

  In S55 corresponding to the blood vessel compliance calculation unit 112, the volume pulse wave MAP1pvr on the transmural pressure PT axis in FIG. 10 calculated by the above S54 (volume pulse wave calculation unit 110) is differentiated, so that FIG. The blood vessel compliance curve indicating the compliance K of the arterial blood vessel wall represented by the infiltration pressure (inclination ΔA / ΔPT) for each transmural pressure PT value is calculated. In addition, the maximum compliance value Kmax which is the maximum value of the vascular compliance curve, and a predetermined constant transmural wall of the vascular soft region which is larger by a predetermined value than the transmural pressure value (about 5 mmHg) corresponding to the maximum compliance value Kmax. The pressure PT value, for example, the compliance K40 when the through-wall pressure PT value is 40 mmHg is determined. FIG. 12 shows a blood vessel compliance curve of a healthy person corresponding to the one-dot chain line of the PA curve of FIG. 8B, and FIG. 11 corresponds to the solid line of the PA curve of FIG. Due to arteriosclerosis, vascular extensibility decreases, Kmax value decreases, and the time constant of the volume pulse wave rising leg in the vascular soft region is extended. That is, the blood vessel compliance curve when the volume pulse wave is a rigid wave is shown.

  In S56 corresponding to the index value calculation unit 114, the compliance index value ACI which is a ratio or ratio thereof based on the maximum compliance value Kmax and the compliance K40 calculated by the blood vessel compliance calculation unit 112, that is, the comparison compliance with the maximum compliance value Kmax. A blood vessel compliance index value ACI, which is a ratio of K40 (K40 / Kmax), is calculated.

  Since the brachial artery has a conductive artery that distributes blood to the periphery, when the size of the brachial artery increases with age, blood vessels increase due to an increase in blood flow. On the other hand, when the blood pressure continuously increases like hypertension, the blood vessel dilates due to the blood pressure load, so vasodilation is also considered as one of arteriosclerosis. The vascular compliance indicated by Kmax increases with vasodilation as shown in FIG. Similarly to Kmax, K40 also increases by vasodilation. Since the rate of increase due to vasodilation of K40 gradually decreases as compared to an increase in Kmax, ACI exhibits a characteristic that decreases with age. That is, the initial decrease in ACI that decreases with age is considered to be due to vasodilation. On the other hand, the blood vessel wall exhibits viscoelastic characteristics, and the volume strain time constant of the pulse wave ascending leg shown in Equation (1) is extended by the decrease in the blood vessel wall elasticity due to arteriosclerosis and the increase in the viscosity contribution. As shown in FIG. 11, if the vasodilation is the same at this time, Kmax decreases, K40 increases, ACI increases, and the strain time (pulse wave rise leg time width UTtime) extends.

  When the blood vessel compliance index value ACI is calculated in this way, in S6 of FIG. 18, the blood vessel compliance index value ACI is displayed in two dimensions with the pulse wave rising leg volume strain time constant of FIG. It is displayed on the image display 18 together with a blood pressure measurement value that is a measurement value.

  As described above, according to the automatic blood pressure measurement device (arterial vascular stiffness measurement device) 10 of this embodiment, the volume pulse wave calculation unit 110 causes at least the rising section of the pulse wave generated in the compression band 12 to be an arterial blood vessel 16. Is converted into a volume pulse wave MAP1pvr indicating a volume change on the transmural pressure axis of the blood vessel, and the blood vessel compliance calculating unit 112 indicates a slope of at least a rising section of the volume pulse wave MAP1pvr indicating the volume change on the transmural pressure axis. The compliance waveform is calculated based on the PA curve, and the index value calculation unit 114 causes the transmural pressure PT5 at the point indicating the maximum compliance Kmax of the vascular compliance waveform to the maximum compliance Kmax of the region I of the vascular compliance waveform. Predetermined compliance corresponding to the through-wall pressure value PT40 included in the region II different from The index value ACI (= K40 / Kmax) of blood vessel compliance, which is the ratio of K40, is calculated by the index value calculation unit 114, and the time constant τc of the volume pulse wave rising leg in the region II is an index indicating volumetric strain characteristics. Therefore, the vascular compliance index value ACI and the pulse wave rising leg volume strain time constant τc are used to accurately determine the degree of arterial vascular sclerosis in the living body regardless of the severity of arterial vasodilation or arteriosclerosis. Can be used as an index value.

  Further, according to the automatic blood pressure measuring device (arterial vascular stiffness measuring device) 10 of the present embodiment, the pulse wave MAP1, the volume pulse wave MAP1pvr on the time axis as a response to the pulse wave, and the transmural pressure PT converted therefrom. Since the rising section of the volume pulse wave MAP1pvr on the axis is a section that is not affected by the reflected wave before the reflected wave from the bifurcation downstream of the compression band 12 of the arterial blood vessel 16 is superimposed, An accurate vascular compliance index ACI that is not affected by waves can be obtained.

  Further, according to the automatic blood pressure measuring device (arterial vascular stiffness measuring device) 10 of this example, the pressure value (PT = 40 mmHg) is the transmural pressure expected at the buckling point in the blood vessel compliance curve of FIG. Since it is the center value of the region II that is larger than the value (PT = 10 mmHg), it is possible to obtain an accurate index ACI of vascular compliance with higher accuracy.

  In addition, according to the automatic blood pressure measurement device (arterial vascular stiffness measurement device) 10 of the present embodiment, the volume pulse wave calculation unit 110 has a constant volume change C applied to the compression band 12 and the compression band 12 The cuff compliance Se is calculated from the change in pressure, and when the pressure in the arterial blood vessel 16 increases based on the cuff pulse wave MAP1 which is pressure vibration in the compression band 12 and the cuff compliance Se, Since the volume pulse wave MAP1pvr representing the volume of the arterial blood vessel that increases per unit length is calculated, an accurate volume pulse wave MAP1pvr is obtained from the pulse wave MAP1 based on the actual cuff compliance Se. By using the plethysmogram MAP1pvr, a more accurate ACI index of vascular compliance can be obtained.

  Further, according to the automatic blood pressure measurement device (arterial vascular stiffness measurement device) 10 of the present embodiment, the compression band 12 includes an intermediate inflation bag 24, a pressure sensor for detecting the pressure in the intermediate inflation bag 24, When a pair of upstream expansion bags 22 and a downstream expansion bag 26 are disposed adjacent to both sides of the intermediate expansion bag 24 and press the upper arm portion 11 of the living body, the pair of upstream expansion bags 22 In addition, the arterial blood vessel 16 in the compressed site, which is the upper arm portion 11 of the living body, is compressed by increasing the pressure in a state where the downstream expansion bag 26 and the intermediate expansion bag 24 are in communication with each other, and the pulse wave MAP1 Is obtained from the intermediate inflatable bag 24, so that a deviation of measured values (short cuff effect) due to a decrease in the compression pressure at the side edge of the compression band 12 is suitably prevented.

  In addition, according to the automatic blood pressure measurement device (arterial vascular stiffness measurement device) 10 of the present embodiment, the volume pulse wave calculation unit 110 has a predetermined constant volume C having a size corresponding to the pulsation of the arterial blood vessel 16. When a gas is applied from the volume pulse generator (constant volume pulse wave generator) 64 into the intermediate expansion bag 24, a cuff compliance Se indicating a change in the internal pressure is calculated, and a constant volume applied to the intermediate expansion bag 24 is obtained. The relationship between the volume value C of gas and the pressure increase value in the intermediate expansion bag 24 detected by the second pressure sensor T2 when the fixed volume of gas is added to the intermediate expansion bag 24 is obtained in advance. Therefore, the cuff compliance Se of the intermediate inflatable bag 24 is, for example, in response to a preset constant period, pulse, or pressure change value, a certain volume of gas from the volume pulse generator 64 into the intermediate inflatable bag. There is an advantage that it is obtained sequentially as it is added.

  As mentioned above, although one Example of this invention was described based on drawing, this invention can be implemented also in another aspect.

  For example, although the compression band 12 of the above-described embodiment is attached to the upper arm portion 11, it may be attached to other parts of the living body, for example, the forearm or ankle.

  In the above-described embodiment, the predetermined comparison compliance K40 for calculating the vascular compliance index value ACI does not necessarily need to be a value when the through-wall pressure PT is 40 mmHg. A predetermined compliance K50 at 50 mmHg may be used.

  In the above-described embodiment, the electronic control unit 70 performs the preliminary (first) blood pressure measurement in the period t1 to t3 in FIG. 7, but the preliminary blood pressure measurement period does not necessarily have to be provided. . Further, in the blood pressure measurement 1 in the interval t1 to t3 in FIG. 7 and in the second blood pressure measurement interval in the period t7 to t17, the systolic blood pressure value SBP and the minimum blood pressure value DBP are obtained using the oscillometric method based on the change in the amplitude of the volume pulse wave. However, using the oscillometric method based on the change in the integral value of the pulse wave, that is, the change in the area of the surface formed by the pulse wave graph on the time axis, the minimum blood pressure value DBP and the maximum blood pressure value SBP are determined. The minimum blood pressure value DBP and the maximum blood pressure value SBP may be determined based on the occurrence and disappearance of Korotkoff sounds detected by a microphone.

  In the above-described embodiment, the plethysmogram MAP1pvr generated in the intermediate expansion bag 24 is such that the interference component from the upstream expansion bag 22 located adjacent to the upstream side is removed. Also good. This interference component is, for example, a pulse wave MAP1 generated in the intermediate expansion bag 24 in the same phase as the pulse wave generated from the upstream expansion bag 22 within the pulse wave propagation time from the upstream expansion bag 22 to the intermediate expansion bag 24. Is identified as being an interference wave from the upstream expansion furnace 22, and the volume pulse wave MAP1pvr generated in the intermediate expansion bag 24 may be corrected using the interference rate that is the ratio.

  In the PA curve generation unit 108 of the above-described embodiment, the relationship between the transmural pressure PT in the arterial blood vessel 16 and the volume per unit length in the arm axis direction of the arterial blood vessel 16 is generated as a PA curve. Since the cross-sectional area and volume of the arterial blood vessel 16 are in a one-to-one relationship, the relationship between the transmural pressure PT in the arterial blood vessel 16 and the cross-sectional area of the arterial blood vessel 16 may be generated as a PA curve.

  The above description is merely an example of the present invention, and various modifications can be made without departing from the spirit of the present invention.

10: Automatic blood pressure measuring device (arterial vascular stiffness measuring device)
11: Upper arm (part of living body)
12: Compression band (cuff)
14: Arterial vascular stiffness measuring device 22: upstream inflation bag 24: intermediate inflation bag 26: downstream inflation bag 64: volume pulse generator (EPG: volume pulse wave generator)
108: PA curve generation unit 110: Volume pulse wave calculation unit 112: Blood vessel compliance calculation unit 114: Index value calculation unit ACI: Blood vessel compliance index value τc: Pulse wave rising leg volume strain time constant

Claims (5)

An arterial vascular stiffness measuring apparatus for measuring the degree of arterial vascular stiffness of a living body based on the shape of a pulse wave generated in a compression band wound around a part of the living body,
A volume pulse wave calculation unit for converting at least a rising section of the pulse wave into a volume pulse wave indicating a volume change on the transmural pressure axis of the arterial blood vessel;
A PA curve generation unit that generates a PA curve indicating the relationship between the transmural pressure in the arterial blood vessel and the volume or cross-sectional area of the arterial blood vessel;
A blood vessel compliance calculating unit that calculates a blood vessel compliance waveform indicating an inclination in at least a rising section of a volume pulse wave indicating a volume change on the transmural pressure axis , based on the PA curve;
Of the vascular compliance waveform calculated by the vascular compliance calculation unit, the vascular compliance waveform with respect to the maximum compliance representing the vascular elasticity characteristic in the region I that is a section until the PA curve reaches the inflection point. A ratio of a predetermined compliance corresponding to a transmural pressure value representing a blood vessel elastic characteristic in the region II which is a section after the PA curve reaches the inflection point, which is different from the transmural pressure at the point indicating the maximum compliance An index value calculation unit for calculating an index value of vascular compliance ,
And a pulse wave ascending leg time constant calculating unit for calculating a volume strain time constant in a rising section of the volume pulse wave .   2. The arterial vascular sclerosis measuring apparatus according to claim 1, wherein the rising section of the pulse wave and volume pulse wave is a section of the pulse wave and volume pulse wave that is not affected by the reflected wave in the arterial blood vessel.   The pressure value set in advance in the rising section of the volume pulse wave in the region II is a value larger than the pressure value of the portion where the maximum compliance of the volume pulse wave is calculated. 1 or 2 arterial vascular stiffness measuring device.   The volume pulse wave calculation unit calculates a cuff compliance indicating a change in pressure in the compression band when a constant volume change is given to the compression band, and the cuff pulse wave which is pressure vibration in the compression band and the pressure band The plethysmogram representing the volume of the arterial blood vessel that increases per unit length of the arterial blood vessel when the pressure in the arterial blood vessel increases is calculated based on the cuff compliance. Item 4. The arterial vascular sclerosis measuring apparatus according to any one of Items 1 to 3.   5. The arteriovascular sclerosis according to claim 1, further comprising a blood pressure measurement unit that measures arterial pressure and pulse wave of the compression band from time series data of the pulse wave generated in the compression band. Degree measuring device.

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