Electronic sphygmomanometer

Abstract

To provide an electronic sphygmomanometer capable of stably obtaining blood pressure value.SOLUTION: An electronic sphygmomanometer includes: a first cuff extending along a circumferential direction of a part to be measured; and a second cuff disposed along an inner peripheral surface of the first cuff. DC voltage P2dc extracted from a second cuff pressure P2 is obtained. Pressure pulse waves P1m transmitted from the part to be measured to the first cuff are extracted from the first cuff pressure P1 to obtain an amplitude A of the pressure pulse waves. On a plane surface which includes the DC voltage P2dc extracted from the second cuff pressure P2 as a first axis and the amplitude A of pressure pulse wave extracted from the first cuff pressure P1 as a second axis, a plurality of data points created by the DC voltage P2dc extracted from the second cuff pressure and the amplitude A of the pressure pulse waves extracted from the first cuff pressure are plotted. A crest-like envelope is created with respect to the data points, and blood pressure value is obtained on the basis of the crest-like envelope.SELECTED DRAWING: Figure 5A

Description

Technical Field

[0001] The present invention relates to an electronic sphygmomanometer, and more particularly to an electronic sphygmomanometer configured to measure blood pressure by an oscillometric method based on a pressure pulse wave caused by a volume change of an artery passing through a site to be measured.

Background Art

[0002] Conventionally, as this type of electronic sphygmomanometer, for example, as disclosed in Patent Document 1 (Japanese Patent Application Laid-Open No. 2018-102868), in order to receive a supply of a pressurizing fluid and compress the wrist as a site to be measured, a bag-shaped pressing cuff configured to extend along the circumferential direction of the wrist, and a sensing cuff configured in a bag shape so as to be able to accommodate a pressure-transmitting fluid, disposed along the inner peripheral surface of the pressing cuff, and configured to cover the artery-passing portion of the wrist. A sphygmomanometer having a cuff structure including the sensing cuff is known. In this electronic sphygmomanometer, the wrist is surrounded by the cuff structure, the outer periphery thereof is surrounded by a belt and worn, and with air as the pressure-transmitting fluid being accommodated in the sensing cuff, air as the pressurizing fluid is supplied to the pressing cuff and pressurized. As a result, the artery-passing portion of the wrist is compressed via the sensing cuff. During the pressurizing process or the decompressing process of the pressing cuff, the CPU (Central Processing Unit) functions as a blood pressure calculation unit, and based on the pressure of the air (sensing cuff pressure) accommodated in the sensing cuff, the blood pressure values (diastolic blood pressure value and systolic blood pressure value) of the wrist as the site to be measured are calculated by the oscillometric method.

[0003] Specifically, in the electronic sphygmomanometer of the above prior art example, blood pressure is calculated by a known algorithm as described in, for example, Patent Document 2 (Japanese Patent Application Laid-Open No. 09-299339). That is, in the pressurization process or decompression process of the pressing cuff, a DC voltage obtained by removing the pulsatile wave (fluctuating component) due to the volume change of the artery from the sensing cuff pressure and the pulsatile wave due to the volume change of the artery are extracted. At the same time, on a plane with the DC voltage extracted from the sensing cuff pressure as the horizontal axis and the amplitude of the pulsatile wave (pulse wave amplitude) extracted from the sensing cuff pressure as the vertical axis, data points formed by the DC voltage and the pulse wave amplitude (specifically, a set of data represented by the DC voltage at the time when a certain beat of the pulsatile wave extracted from the sensing cuff pressure occurs and the pulse wave amplitude for that beat of the pulsatile wave extracted from the sensing cuff pressure) are plotted in plural. Further, adjacent data points among the above data points are connected by line segments to create a mountain-shaped envelope line. Then, the horizontal axis direction components of the points where the low-pressure side portion and the high-pressure side portion of the mountain-shaped envelope line cross a predetermined threshold value with respect to the horizontal axis for the maximum peak are calculated as the diastolic blood pressure value and the systolic blood pressure value, respectively.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the human wrist, a tendon passes between the radial artery and the ulnar artery, and the degree to which the tendon bulges with respect to the radial artery and the ulnar artery varies among humans. Therefore, depending on the degree of adhesion of the sensing cuff to the wrist, the portion of the sensing cuff in contact with the tendon may be crushed by the tendon, and the sensing cuff may be disconnected (fluid flow is blocked) in the circumferential direction around the wrist. For this reason, the pulse wave extracted from the pressure of the sensing cuff may become unstable.

[0006] Here, in the conventional electronic blood pressure monitor, in order to calculate the blood pressure value by the oscillometric method, on a plane having the DC pressure extracted from the pressure of the sensing cuff on the horizontal axis and the amplitude of the pulse wave (pulse wave amplitude) on the vertical axis, the mountain-shaped envelope is created. That is, the mountain-shaped envelope is created using data points including the amplitude of the pulse wave (pulse wave amplitude) extracted from the pressure of the sensing cuff as a component in the vertical axis direction. For this reason, it is considered that the blood pressure value cannot be obtained stably.

[0007] Therefore, an object of the present invention is to provide an electronic blood pressure monitor capable of stably obtaining a blood pressure value.

Means for Solving the Problems

[0008] To solve the above problems, the electronic blood pressure monitor of this disclosure is An electronic blood pressure monitor configured to measure blood pressure by the oscillometric method based on a pulse wave due to a volume change of an artery passing through a measurement site, A bag-shaped first cuff configured to extend along the circumferential direction of the measurement site in order to receive a supply of pressurizing fluid and compress the measurement site; A second cuff configured in a bag shape to be able to accommodate a pressure-transmitting fluid and arranged along the inner peripheral surface of the first cuff; A first pressure sensor that detects a first cuff pressure that is the pressure of the first cuff; A second pressure sensor that detects a second cuff pressure that is the pressure of the second cuff; A pressure control unit that supplies and pressurizes the pressurizing fluid to the first cuff, or discharges the pressurizing fluid from the first cuff to reduce the pressure is provided, In a state where the first and second cuffs surround the measurement site and are integrally attached, and the pressure transmission fluid is accommodated in the second cuff, during the pressurization process of supplying the pressurizing fluid to the first cuff or the depressurization process of discharging the pressurizing fluid from the first cuff by the pressure control unit, a DC voltage extracted from the second cuff pressure detected by the second pressure sensor, or a converted DC voltage corresponding to the extracted DC voltage, and a DC voltage acquisition unit that acquires the converted DC voltage; During the pressurization process or the depressurization process, the pulse wave amplitude acquisition unit extracts the pulse pressure wave transmitted from the measurement site to the first cuff from the first cuff pressure detected by the first pressure sensor and acquires the amplitude of the pulse pressure wave; It is provided with a first blood pressure calculation unit, The first blood pressure calculation unit On a plane including the DC voltage extracted from the second cuff pressure or the converted DC voltage as the first axis and the amplitude of the pulse pressure wave extracted from the first cuff pressure as the second axis, during the pressurization process or the depressurization process, a plurality of data points formed by the DC voltage extracted from the second cuff pressure or the converted DC voltage and the amplitude of the pulse pressure wave extracted from the first cuff pressure are plotted; Connect adjacent data points among the data points with line segments to create a mountain-shaped envelope line; Based on the mountain-shaped envelope line, obtain the diastolic blood pressure value and the systolic blood pressure value It is characterized by this.

[0009] In this specification, the "extracted DC voltage" from the second cuff pressure means the pressure obtained by removing the pulse pressure wave (fluctuating component) due to the volume change of the artery passing through the measurement site from the second cuff pressure.

[0010] The "converted DC voltage corresponding to the extracted DC voltage" refers to, for example, the DC voltage obtained by converting the DC voltage extracted from the first cuff pressure to the DC voltage extracted from the second cuff based on the cuff pressure correspondence relationship (described later) between the DC voltage extracted from the first cuff pressure and the DC voltage extracted from the second cuff pressure.

[0011] The above-mentioned "first axis" typically refers to the horizontal axis, and the above-mentioned "second axis" typically refers to the vertical axis. Also, the above-mentioned "plane" typically refers to a plane including the first axis and the second axis as orthogonal coordinates.

[0012] The "data point formed by the DC voltage extracted from the second cuff pressure or the converted DC voltage and the amplitude of the pressure pulse wave extracted from the first cuff pressure" means, in the pressurization process or the depressurization process, the DC voltage (the DC voltage extracted from the second cuff pressure or the converted DC voltage) at the time when a certain beat of the pressure pulse wave occurs, and the amplitude (pulse wave amplitude) of that beat of the pressure pulse wave extracted from the first cuff pressure, which represents a point of a set of data.

[0013] In the electronic blood pressure monitor of this disclosure, with the first and second cuffs surrounding the measurement site and integrally attached, and with the fluid for pressure transmission contained in the second cuff, a pressurization process in which the pressure control unit supplies the pressurizing fluid to the first cuff or a depressurization process in which the pressurizing fluid is discharged from the first cuff is started. In the pressurization process or the depressurization process, the DC voltage acquisition unit acquires the DC voltage extracted from the second cuff pressure detected by the second pressure sensor or the converted DC voltage corresponding to the extracted DC voltage. At the same time, in the pressurization process or the depressurization process, the pulse wave amplitude acquisition unit extracts the pressure pulse wave transmitted from the measurement site to the first cuff from the first cuff pressure detected by the first pressure sensor and acquires the amplitude of the pressure pulse wave. The first blood pressure calculation unit - On a plane having as the first axis the DC voltage extracted from the second cuff pressure or the converted DC voltage, and as the second axis the amplitude of the pressure pulse wave extracted from the first cuff pressure, during the pressurization process or the depressurization process, a plurality of data points formed by the DC voltage extracted from the second cuff pressure or the converted DC voltage and the amplitude of the pressure pulse wave extracted from the first cuff pressure are plotted. - Adjacent data points among the above data points are connected by line segments to create a mountain-shaped envelope. - Based on the mountain-shaped envelope, a diastolic blood pressure value and a systolic blood pressure value are obtained. For example, the first blood pressure calculation unit obtains, as the diastolic blood pressure value and the systolic blood pressure value, the components in the first axis direction of the points where the portions on the low-pressure side and the high-pressure side with respect to the first axis cross a predetermined threshold value for the maximum peak of the mountain-shaped envelope.

[0014] Thus, in this electronic blood pressure monitor, in order to calculate the blood pressure value by the oscillometric method, on a plane having as the first axis the DC voltage extracted from the second cuff pressure, or the converted DC voltage corresponding to the extracted DC voltage, and as the second axis the amplitude of the pressure pulse wave extracted from the first cuff pressure, the mountain-shaped envelope is created. And the mountain-shaped envelope is created using the data points including the amplitude of the pressure pulse wave (pulse wave amplitude) extracted from the first cuff pressure as the component in the second axis direction. Here, during the pressurization process or the depressurization process, the first cuff is in a state of being expanded by the pressurizing fluid, and moreover, indirectly surrounds the measurement site via the second cuff. Therefore, the first cuff is less affected by the degree to which the tendon passing through the measurement site bulges and / or the degree of adhesion of the second cuff to the measurement site. As a result, the tendon is not divided (the flow of the fluid is blocked) in the circumferential direction surrounding the measurement site. Therefore, the amplitude of the pressure pulse wave (pulse wave amplitude) extracted from the first cuff pressure becomes stable as the component in the second axis direction of each data point. Therefore, in this electronic blood pressure monitor, the blood pressure value can be stably obtained.

[0015] Depending on the degree to which the tendon passing through the measurement site bulges and / or the degree of adhesion of the second cuff to the measurement site, in addition to the pulse wave extracted from the second cuff pressure, it is also assumed that the DC voltage extracted from the second cuff pressure becomes unstable. Therefore, in the electronic blood pressure monitor of one embodiment, during the pressurization process or the depressurization process, the DC voltage acquisition unit extracts the DC voltage from the first cuff pressure and extracts the DC voltage from the second cuff pressure, based on the cuff pressure correspondence relationship between the DC voltage extracted from the first cuff pressure and the DC voltage extracted from the second cuff pressure, obtains an approximation formula for converting the DC voltage extracted from the first cuff pressure to the DC voltage extracted from the second cuff, obtains the converted DC voltage by converting the DC voltage extracted from the first cuff pressure to the DC voltage extracted from the second cuff according to the approximation formula, the first blood pressure calculation unit plots a plurality of data points formed by the converted DC voltage derived from the first cuff pressure and the amplitude of the pulse wave extracted from the first cuff pressure on the plane having the converted DC voltage derived from the first cuff pressure as the first axis and the amplitude of the pulse wave extracted from the first cuff pressure as the second axis during the pressurization process or the depressurization process, connects adjacent data points among the data points with line segments to create a mountain-shaped envelope, and obtains the diastolic blood pressure value and the systolic blood pressure value based on the mountain-shaped envelope. It is characterized by the above.

[0016] In this specification, the "corresponding relationship between cuff pressures between the DC voltage extracted from the first cuff pressure and the DC voltage extracted from the second cuff pressure" means the corresponding relationship between cuff pressures determined by the dimensions of the first cuff and the second cuff (particularly, the width dimension along the direction in which the artery passes through the measurement site). Specifically, generally in a cuff of a sphygmomanometer, in order for the internal pressure of the cuff to be equal to the pressure applied to the measurement site, a dimension ratio is required such that the width dimension of the cuff is 1.2 times or more the diameter of the measurement site, or about 40% or more of the perimeter length of the measurement site. Here, the first cuff in the present invention is not limited by such a dimension ratio. Therefore, a phenomenon may occur in which the first cuff pressure becomes larger than the second cuff pressure. In this specification, such a corresponding relationship between cuff pressures is referred to as the "corresponding relationship between cuff pressures".

[0017] In the electronic sphygmomanometer of this embodiment, during the pressurization process or the depressurization process, the DC voltage acquisition unit - extracts the DC voltage from the first cuff pressure and extracts the DC voltage from the second cuff pressure, - obtains an approximate formula for converting the DC voltage extracted from the first cuff pressure to the DC voltage extracted from the second cuff based on the corresponding relationship between cuff pressures between the DC voltage extracted from the first cuff pressure and the DC voltage extracted from the second cuff pressure, - acquires the converted DC voltage by converting the DC voltage extracted from the first cuff pressure to the DC voltage extracted from the second cuff according to the approximate formula.

[0018] Furthermore, the first blood pressure calculation unit - plots a plurality of data points formed by the converted DC voltage derived from the first cuff pressure and the amplitude of the pressure pulse wave extracted from the first cuff pressure on the plane including the converted DC voltage derived from the first cuff pressure as the first axis and the amplitude of the pressure pulse wave extracted from the first cuff pressure as the second axis during the pressurization process or the depressurization process, - creates a mountain-shaped envelope by connecting adjacent data points among the data points with line segments, - Based on the above mountain-shaped envelope, determine the diastolic blood pressure value and the systolic blood pressure value.

[0019] Thus, in the electronic sphygmomanometer of this embodiment, in order to calculate the blood pressure value by the oscillometric method, on a plane including the converted DC voltage derived from the first cuff pressure as the first axis and the amplitude of the plethysmogram extracted from the first cuff pressure as the second axis, the mountain-shaped envelope is created. Here, as described above, during the pressurization process or the decompression process, the first cuff is in a state of being expanded by the pressurizing fluid. Therefore, the first cuff is less affected by the degree to which the tendon passing through the measurement site bulges and / or the degree of adhesion of the second cuff to the measurement site. As a result, the tendon does not interrupt (block the fluid flow) in the circumferential direction around the measurement site. Therefore, the converted DC voltage derived from the first cuff pressure becomes stable as the component in the first axis direction of each data point. Therefore, in the electronic sphygmomanometer of this embodiment, even if not only the plethysmogram extracted from the second cuff pressure but also the DC voltage extracted from the second cuff pressure is unstable, the blood pressure value can be stably determined.

[0020] In the electronic sphygmomanometer of one embodiment, the DC voltage acquisition unit obtains the approximate formula based on the correspondence relationship between the cuff pressures over a predetermined first pressure range during the pressurization process or the decompression process. It is characterized by this.

[0021] In this specification, the "predetermined first pressure range" refers to, for example, a pressure range from 40 mmHg to 140 mmHg. This first pressure range is typically set to cover the diastolic blood pressure value and the systolic blood pressure value of an average user (the person being measured).

[0022] In the electronic sphygmomanometer of this embodiment, the DC voltage acquisition unit obtains the approximate formula based on the correspondence relationship between the cuff pressures over a predetermined first pressure range in the pressurization process or the depressurization process. In this way, when obtaining the approximate formula based on the correspondence relationship between the cuff pressures over a predetermined first pressure range, for example, the process of setting a pressure range each time blood pressure is measured becomes unnecessary, and the overall process is simplified.

[0023] In the electronic sphygmomanometer of one embodiment, prior to the operation of the DC voltage acquisition unit, it includes a second blood pressure calculation unit that calculates a provisional blood pressure value. The second blood pressure calculation unit On a plane including the DC voltage extracted from the second cuff pressure as the first axis and the amplitude of the plethysmogram wave extracted from the first cuff pressure or the second cuff pressure as the second axis, in the pressurization process or the depressurization process, a plurality of data points formed by the DC voltage extracted from the second cuff pressure and the amplitude of the plethysmogram wave extracted from the first cuff pressure or the second cuff pressure are plotted. Among the data points, adjacent data points are connected by line segments to create a mountain-shaped envelope. Based on the mountain-shaped envelope, a provisional systolic blood pressure value is obtained. As soon as the provisional systolic blood pressure value is obtained, the pressure control unit discharges the pressurizing fluid from the first cuff to reduce the pressure. The DC voltage acquisition unit obtains the approximate formula based on the correspondence relationship between the cuff pressures over a second pressure range from a predetermined lower pressure value to the maximum pressurization value corresponding to the provisional systolic blood pressure value in the pressurization process or the depressurization process. It is characterized by this.

[0024] In this specification, the "predetermined lower pressure value" refers to, for example, 40 mmHg. The "maximum pressurization value corresponding to the provisional systolic blood pressure value" refers to the maximum value of the first cuff pressure reached until the provisional systolic blood pressure value is calculated and the first cuff is depressurized.

[0025] In the electronic sphygmomanometer of this embodiment, prior to the operation of the DC voltage acquisition unit, the second blood pressure calculation unit calculates a provisional blood pressure value by the oscillometric method. Specifically, the second blood pressure calculation unit - On a plane including the DC voltage extracted from the second cuff pressure as the first axis and the amplitude of the pulse wave extracted from the first cuff pressure or the second cuff pressure as the second axis, during the pressurization process or the depressurization process, a plurality of data points formed by the DC voltage extracted from the second cuff pressure and the amplitude of the pulse wave extracted from the first cuff pressure or the second cuff pressure are plotted. - Connect adjacent data points among the data points with line segments to create a mountain-shaped envelope. - Obtain a provisional systolic blood pressure value based on the mountain-shaped envelope. - As soon as the provisional systolic blood pressure value is obtained, the pressure control unit discharges the pressurizing fluid from the first cuff to depressurize it.

[0026] The DC voltage acquisition unit - Obtains the approximate formula based on the cuff pressure correspondence relationship over a second pressure range from a predetermined lower pressure value to a maximum pressurization value corresponding to the provisional systolic blood pressure value during the pressurization process or the depressurization process.

[0027] Thus, in the electronic sphygmomanometer of this embodiment, the approximate formula is obtained based on the cuff pressure correspondence relationship over a second pressure range from a predetermined lower pressure value to a maximum pressurization value corresponding to the provisional systolic blood pressure value during the pressurization process or the depressurization process. Therefore, for example, if the user's systolic blood pressure value is relatively low (for example, about 110 mmHg), the maximum pressurization value will also be correspondingly low, and the second pressure range can be set as a range from, for example, about 40 mmHg to 110 mmHg. In such a case, compared with the case of obtaining the approximate formula based on the cuff pressure correspondence relationship over a predetermined first pressure range, the time and physical burden for the user's blood pressure measurement can be reduced.

[0028] In the electronic sphygmomanometer of one embodiment, A storage unit that stores the past diastolic blood pressure value and systolic blood pressure value obtained by the first blood pressure calculation unit is provided. The DC pressure acquisition unit obtains the approximation formula based on the cuff pressure correspondence relationship over the third pressure interval corresponding to the past diastolic blood pressure value and systolic blood pressure value stored in the storage unit during the pressurization process or the depressurization process. It is characterized by this.

[0029] In this specification, the "past diastolic blood pressure value and systolic blood pressure value" refers to, for example, the diastolic blood pressure value and systolic blood pressure value obtained in the previous measurement.

[0030] In the electronic blood pressure monitor of this embodiment, the storage unit stores the past diastolic blood pressure value and systolic blood pressure value obtained by the first blood pressure calculation unit. The DC pressure acquisition unit obtains the approximation formula based on the cuff pressure correspondence relationship over the third pressure interval corresponding to the past diastolic blood pressure value and systolic blood pressure value stored in the storage unit during the pressurization process or the depressurization process. In this case, the pressure interval can be set according to the user's past diastolic blood pressure value and systolic blood pressure value. Conversely, the process of setting the pressure interval in this blood pressure measurement becomes unnecessary. For example, compared with the case where the second blood pressure calculation unit described above calculates a provisional blood pressure value, the process for calculating the provisional blood pressure value becomes unnecessary, and the overall process becomes simple. Therefore, the time and physical burden on the user for blood pressure measurement can be reduced.

[0031] In an electronic blood pressure monitor of an embodiment, A fluid accommodation control unit that performs control to supply and accommodate the fluid for pressure transmission to the second cuff in a mounted state where the first and second cuffs are mounted around the measurement site. It is characterized by including this.

[0032] In the electronic sphygmomanometer of this embodiment, the fluid accommodation control unit performs control to supply and accommodate the fluid for pressure transmission to the second cuff in the mounted state. Therefore, each time blood pressure is measured, the amount of the fluid for pressure transmission accommodated in the second cuff can be stabilized according to the mounted state. Note that when blood pressure measurement is completed, the fluid for pressure transmission may be discharged from the second cuff.

Advantages of the Invention

[0033] As is clear from the above, according to the electronic sphygmomanometer of this disclosure, a blood pressure value can be obtained stably.

Brief Description of the Drawings

[0034]

Figure 1

Figure 2

Figure 3

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Figure 5A

Figure 5B

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Figure 7A

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Figure 7C

Figure 8A

Figure 8B

Figure 8C

Figure 9A

Figure 9B

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BEST MODE FOR CARRYING OUT THE INVENTION

[0035] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0036] (Schematic Configuration of Blood Pressure Monitor) FIG. 1 shows an external view of a blood pressure monitor (designated as a whole by reference numeral 1) according to an embodiment of the present invention as seen obliquely with the belt 2 open. FIG. 2 shows a cross section perpendicular to the left wrist 90 in a state where the blood pressure monitor 1 is attached to the left wrist 90 as a measurement site of a user (subject) (however, illustration of the main body 10 and the belt 2 is omitted).

[0037] As shown in FIG. 1, this blood pressure monitor 1 generally includes a main body 10, a belt 2 extending from the main body 10 and to be worn around the left wrist 90 as a measurement site, and a cuff structure 20 having a belt shape with one end 20f attached to the main body 10. The dimension in the width direction X of the belt 2 is set to 29 mm in this example. Also, the thickness of the belt 2 is set to 2 mm in this example.

[0038] In this example, the main body 10 has a substantially short cylindrical case 10B, a circular glass 10A attached to the upper part (in FIG. 1) of the case 10B, and a back cover (not shown) attached to the lower part of the case 10B.

[0039] In addition, a display 50 forming a display screen is provided in the glass 10A at the upper part of the case 10B. On the front side (in FIG. 1) of the main body 10, a measurement switch 52A for instructing the start or stop of blood pressure measurement, a home switch 52B for returning the display screen of the display 50 to a predetermined home screen, and a record call switch 52C for instructing the display 50 to display measurement records such as past blood pressure and activity amount are provided (these switches are collectively referred to as the operation unit 52). Further, a blood pressure measurement element including a pump 30 is mounted inside the main body 10 (to be described in detail later).

[0040] The belt 2 includes a belt-shaped first belt portion 3 extending from the main body 10 in one direction (right side in FIG. 1) and a belt-shaped second belt portion 4 extending from the main body 10 in the other direction (left side in FIG. 1). The base portion 3e of the first belt portion 3 close to the main body 10 is rotatably attached to a pair of lugs 10B1 and 10B2 protruding from the main body 10 to the right side via a connecting rod 7 (a known spring rod) extending in the belt width direction X as indicated by double arrows A. Similarly, the base portion 4e of the second belt portion 4 close to the main body 10 is rotatably attached to a pair of lugs 10B3 and 10B4 protruding from the main body 10 to the left side via a connecting rod 8 (a known spring rod) extending in the belt width direction X as indicated by double arrows B.

[0041] A lock 5 is attached to the distal end portion 3f of the first belt portion 3 far from the main body 10. The lock 5 is of a known type and includes a substantially U-shaped frame body 5A, a locking rod 5B, and a connecting rod 5C extending in the belt width direction X. The frame body 5A and the locking rod 5B are rotatably attached to the distal end portion 3f of the first belt portion 3 far from the main body 10 via the connecting rod 5C as indicated by double arrows C. When the first belt portion 3 and the second belt portion 4 are fastened, a portion of the second belt portion 4 continuous with the distal end portion 4f is passed through the frame body 5A of the lock 5, and the locking rod 5B of the lock 5 is inserted into any one of a plurality of small holes 4w, 4w,... of the second belt portion 4. Thereby, the first belt portion 3 and the second belt portion 4 are fastened.

[0042] In this example, the first belt portion 3 and the second belt portion 4 that constitute the belt 2 are made of a plastic material that has flexibility in the thickness direction and substantially exhibits non-elasticity in the longitudinal direction (corresponding to the circumferential direction Y of the left wrist 90). Thereby, when worn, the belt 2 can easily wrap around and restrain the outer peripheral side of the cuff structure 20, and can assist in compressing the left wrist 90 during blood pressure measurement described later. Note that the first belt portion 3 and the second belt portion 4 may be made of a leather material.

[0043] The cuff structure 20 includes a curler 24 disposed on the outermost periphery, a pressing cuff 23 as a first cuff disposed along the inner peripheral surface of the curler 24, a back plate 22 as a reinforcing plate disposed along the inner peripheral surface of the pressing cuff 23, and a sensing cuff 21 as a second cuff disposed along the inner peripheral surface of the back plate 22. The curler 24, the pressing cuff 23, the back plate 22, and the sensing cuff 21 each have an elongated strip shape in one direction (Y direction). In this example, the dimensions in the width direction X of the curler 24, the pressing cuff 23, the back plate 22, and the sensing cuff 21 are set to 28 mm, 25 mm, 23 mm, and 15 mm, respectively, so as to be gradually slightly smaller than the dimension in the width direction X of the belt 2.

[0044] As can be seen from FIG. 2, the sensing cuff 21 is formed in a bag shape by welding the peripheral edges of a pair of stretchable sheets to each other. In this example, the material of the pair of sheets forming the sensing cuff 21 is a polyurethane sheet (thickness t = 0.15 mm). The inner peripheral surface 20a of the cuff structure 20 is formed by one of the sheets of the sensing cuff 21 (the side in contact with the left wrist 90).

[0045] In this example, the pressing cuff 23 is configured in a bag shape by welding the peripheral edges of a pair of stretchable sheets to each other, similar to the sensing cuff 21. The material of the pair of sheets forming the pressing cuff 23 is made of a polyurethane sheet (thickness t = 0.15 mm) in this example. Here, the pressing cuff 23 may be configured by laminating a plurality of such bags in the thickness direction and connecting the plurality of bags to each other so as to allow fluid flow. In such a case, the expansion and contraction stroke in the thickness direction of the pressing cuff 23 can be increased.

[0046] The back plate 22 is made of a plate-shaped resin (in this example, polypropylene) with a thickness of about 1 mm in this example. As can be seen from FIG. 2, the back plate 22 extends in a strip shape beyond the length of the sensing cuff 21 in the longitudinal direction Y (corresponding to the circumferential direction of the left wrist 90). Therefore, the back plate 22 acts as a reinforcing plate and can transmit the pressing force from the pressing cuff 23 throughout the longitudinal direction Y (corresponding to the circumferential direction of the left wrist 90) of the sensing cuff 21. Further, on the inner peripheral surface 22a and the outer peripheral surface 22b of the back plate 22, a plurality of grooves 22d1 and 22d2 having a V-shaped or U-shaped cross section extending in the width direction X are provided in parallel with each other at intervals in the longitudinal direction Y. These grooves 22d1 and 22d2 are provided at the same positions corresponding to each other between the inner peripheral surface 22a and the outer peripheral surface 22b of the back plate 22. As a result, the back plate 22 is thinner at the locations of these grooves 22d1 and 22d2 than at other locations, and is more easily bent. Therefore, when the user wraps the left wrist 90 and the cuff structure 20 together with the belt 2 during wearing, the back plate 22 does not prevent the cuff structure 20 from bending along the circumferential direction Y of the left wrist 90.

[0047] In this example, the curler 24 is made of a resin plate (in this example, polypropylene) having a certain degree of flexibility and hardness with a thickness of about 1 mm. As shown in FIG. 1, this curler 24 has a curved shape along the circumferential direction Y that surrounds the left wrist 90 in its natural state. Thereby, the shape of the cuff structure 20 in its natural state is maintained in a state curved along the circumferential direction Y of the left wrist 90. In this example, the outer peripheral surface 20b of the cuff structure 20 is constituted by the curler 24.

[0048] At the end on the main body side with respect to the longitudinal direction Y of the sensing cuff 21, an air pipe 38 (see FIG. 3) for supplying a fluid for pressure transmission (in this example, air) to the sensing cuff 21 or discharging the fluid for pressure transmission from the sensing cuff 21 is attached. Similarly, at the end on the main body side with respect to the longitudinal direction Y of the pressing cuff 23, an air pipe 39 (see FIG. 3) for supplying a pressurizing fluid (in this example, air) to the pressing cuff 23 or discharging the pressurizing fluid from the pressing cuff 23 is attached. These air pipes 38 and 39, together with the end on the main body side of the curler 24, extend into the case 10B of the main body 10 through the gap between the case 10B of the main body 10 and the back cover shown in FIG. 1. In this manner, as shown in FIG. 1, one end 20f of the cuff structure 20 is attached to the main body 10. The other end 20e of the cuff structure 20 (corresponding to the tip of the curler 24) is a free end.

[0049] FIG. 3 shows the block configuration of the control system of the sphygmomanometer 1. In addition to the aforementioned display 50 and operation unit 52, the main body 10 of the sphygmomanometer 1 is equipped with a CPU (Central Processing Unit) 110 as a control unit, a memory 51 as a storage unit, a first pressure sensor 31 for detecting the pressure of the pressing cuff 23, a second pressure sensor 32 for detecting the pressure of the sensing cuff 21, a pump 30, an on-off valve 33, and a switching valve 34 as blood pressure measurement elements for performing blood pressure measurement. Further, the main body 10 is equipped with a pump drive circuit 300, A / D conversion circuits 310 and 320, an on-off valve drive circuit 330, and a switching valve drive circuit 340.

[0050] In this example, the display 50 is composed of an LCD (Liquid Crystal Display), and in accordance with the control signal from the CPU 110, it displays information related to blood pressure measurement such as blood pressure measurement results and other information. Note that the display 50 is not limited to an LCD, and may be composed of other types of displays 50, such as an organic EL (Electro Luminescence) display. Also, the display 50 may include an LED (Light Emitting Diode).

[0051] As described above, the operation unit 52 includes a measurement switch 52A for instructing the start or stop of blood pressure measurement, a home switch 52B for returning the display screen of the display 50 to a predetermined home screen, and a record call switch 52C for instructing the display 50 to display measurement records such as past blood pressure and activity amount. In this example, these switches 52A to 52C are push-type switches, and input an operation signal corresponding to an instruction such as the start or stop of blood pressure measurement by the user to the CPU 110. Note that the operation unit 52 is not limited to push-type switches, and may be, for example, a pressure-sensitive (resistive) or proximity (capacitive) touch panel switch. Also, a microphone (not shown) may be provided to input an instruction to start blood pressure measurement by the user's voice.

[0052] The memory 51 non-temporarily stores program data for controlling the blood pressure monitor 1, data used for controlling the blood pressure monitor 1, setting data for setting various functions of the blood pressure monitor 1, data of the measurement results of blood pressure values, etc. Also, the memory 51 is used as a work memory when the program is executed.

[0053] The CPU 110 executes various functions as a control unit according to a program for controlling the sphygmomanometer 1 stored in the memory 51. For example, when executing the blood pressure measurement function, the CPU 110, in response to an instruction to start blood pressure measurement from the measurement switch 52A of the operation unit 52, performs control to drive the pump 30, the on-off valve 33, and the switching valve 34 based on signals from the first pressure sensor 31 and the second pressure sensor 32, and also performs control to calculate blood pressure values, pulse rates, etc.

[0054] In this example, the pump 30 is a piezoelectric pump and is driven by a pump drive circuit 300 based on a control signal given from the CPU 110. This pump 30 is configured to supply air through the air pipe 38b. The on-off valve 33 is driven by an on-off valve drive circuit 330 based on a control signal given from the CPU 110 and opens and closes. This on-off valve 33 is a normally-closed valve, which closes when not energized and opens when energized to discharge air into the atmosphere through the air pipe 38c. Note that this on-off valve 33 has the function of a check valve and the discharged air does not flow back.

[0055] In this example, the first pressure sensor 31 and the second pressure sensor 32 are each a piezoresistive pressure sensor. The first pressure sensor 31 detects the pressure in the pressure cuff 23 (referred to as the "pressure cuff pressure") through the air pipes 38 and 38a. The second pressure sensor 32 detects the pressure in the sensing cuff 21 (referred to as the "sensing cuff pressure") through the air pipes 39 and 39a. The outputs (resistance values) of the first pressure sensor 31 and the second pressure sensor 32 are each converted from an analog signal to a digital signal by A / D conversion circuits 310 and 320 and input to the CPU 110.

[0056] The switching valve 34 is a 3-port 2-position solenoid valve in this example. One port 34a of the switching valve 34 is connected to the air pipe 38b leading to the pump 30 and the air pipe 38c leading to the on-off valve 33, which merge into one air pipe 38d and are connected so that fluid can flow through. The remaining ports 34b and 34c of the switching valve 34 are connected to the air pipes 38e and 39f respectively so that fluid can flow through. These air pipes 38e and 39f are connected to the air pipe 38 leading to the pressing cuff 23 and the air pipe 39 leading to the sensing cuff 21 respectively so that fluid can flow through. The switching valve drive circuit 340 is configured to switch the switching valve 34 to either the rest position or the operating position based on a control signal given from the CPU 110.

[0057] Specifically, when the switching valve 34 is de-energized, it takes the rest position and connects the air pipe 38d and the air pipe 38e so that fluid can flow through. Thereby, the pump 30 and the on-off valve 33, and the pressing cuff 23 and the first pressure sensor 31 are connected so that fluid can flow through via the air pipes 38b, 38c, 38d, 38e, 38, 38a. At this time, the sensing cuff 21, together with the second pressure sensor 32, is disconnected from and sealed off from the pump 30 and the on-off valve 33. On the other hand, when the switching valve 34 is energized, it takes the operating position and connects the air pipe 38d and the air pipe 39f so that fluid can flow through. Thereby, the pump 30 and the on-off valve 33, and the sensing cuff 21 and the second pressure sensor 32 are connected so that fluid can flow through via the air pipes 38b, 38c, 38d, 39f, 39, 39a. At this time, the pressing cuff 23, together with the first pressure sensor 31, is disconnected from and sealed off from the pump 30 and the on-off valve 33.

[0058] The power supply unit 53 is a rechargeable secondary battery in this example. The power supply unit 53 supplies power to each part of this sphygmomanometer 1 including the elements mounted on the main body 10, which in this example are the CPU 110, the memory 51, the pump 30, the first pressure sensor 31, the second pressure sensor 32, the on-off valve 33, and the switching valve 34. Note that the power supply unit 53 may be mounted on the main body 10 or on the belt 2.

[0059] (First Example of Blood Pressure Measurement Operation) FIG. 4 shows a first example of an operation flow in which the sphygmomanometer 1 measures blood pressure by the oscillometric method.

[0060] Prior to the start of blood pressure measurement, as shown in FIG. 2, it is assumed that the sphygmomanometer 1 (cuff structure 20 thereof) is worn so as to surround the left wrist 90 as the measurement site. Although the illustration of the main body 10 and the belt 2 is omitted in FIG. 2, the main body 10 is located below the left wrist 90. In FIG. 2, the radius 93, ulna 94, radial artery 91, ulnar artery 92, and tendon 96 of the left wrist 90 are shown. In the wearing state shown in FIG. 2, on the inner peripheral side of the curl 24 included in the cuff structure 20, the bag-shaped pressing cuff 23 extends along the circumferential direction Y of the left wrist 90. Further, the bag-shaped sensing cuff 21 included in the cuff structure 20 is disposed on the inner peripheral side of the pressing cuff 23, contacts the left wrist 90, and extends in the circumferential direction Y so as to cross the artery passing portion 90a of the left wrist 90. Furthermore, the back plate 22 included in the cuff structure 20 is inserted between the pressing cuff 23 and the sensing cuff 21 and extends along the circumferential direction Y of the left wrist 90.

[0061] In this wearing state, the pulse wave due to the volume change of the artery (radial artery 91, ulnar artery 92) passing through the left wrist 90 is transmitted to the pressing cuff 23 through the sensing cuff 21 and the back plate 22. During blood pressure measurement, the CPU 110 can remove the pulse wave (exemplified by reference numeral P1m in the enlarged elliptical region B in FIG. 5A) from the pressing cuff pressure and the sensing cuff pressure respectively to extract the DC pressure. At the same time, the amplitude of the pulse wave (referred to as "pulse wave amplitude") can be obtained from the pressing cuff pressure and the sensing cuff pressure respectively. Note that the time required for the transmission of the pulse wave from the sensing cuff 21 to the pressing cuff 23 is assumed to be negligible (the same applies hereinafter).

[0062] Before the start of blood pressure measurement, since the on-off valve 33 is de-energized, it is closed. Also, since the switching valve 34 is de-energized, it is in the rest position.

[0063] In that state, when the user presses the measurement switch 52A of the operation unit 52 provided on the main body 10 (step S101 in FIG. 4), the CPU 110 initializes the processing memory area (step S102 in FIG. 4). Further, the CPU 110 turns off the pump 30 via the pump drive circuit 300, temporarily maintains the on-state of the on-off valve 33, and exhausts the air in the pressing cuff 23. Subsequently, control is performed to adjust the first pressure sensor 31 and the second pressure sensor 32 to 0 mmHg.

[0064] Next, in step S103 of FIG. 4, the CPU 110 closes the on-off valve 33. This closed state of the on-off valve 33 is maintained until step S104 to step S114 in FIG. 4. Subsequently, in step S104, the CPU 110 switches the switching valve 34 to the operating position. Thereby, the pump 30 and the on-off valve 33, and the sensing cuff 21 and the second pressure sensor 32 are fluidly connected via the air pipes 38b, 38c, 38d, 39f, 39, 39a.

[0065] Next, in step S105 of FIG. 4, the CPU 110 acts as a fluid containment control unit, drives the pump 30, and supplies air as a pressure-transmitting fluid to the sensing cuff 21 through the air pipes 38b, 38d, 39f, 39 in this order. Next, in step S106, the CPU 110 determines whether or not a predetermined time (predetermined time; for example, within the range of 3 seconds to 10 seconds) has elapsed. Here, if the predetermined time has not elapsed (NO in step S106), the process returns to step S105, and the supply of air continues until the predetermined time elapses. Then, when the predetermined time has elapsed (YES in step S106), the process proceeds to step S107, and the pump 30 is stopped. In this way, prior to the start of pressurization of the pressing cuff 23, air as a pressure-transmitting fluid is automatically enclosed in the sensing cuff 21 in a predetermined amount. Here, the "predetermined amount" refers to an amount that can avoid a situation in which the bag forming the sensing cuff 21 is crushed in the thickness direction Z (see FIG. 2) by the pressure Pc of the pressing cuff 23 and the sheet forming the bag comes into close contact. Thereby, the amount of air contained in the sensing cuff 21 can be stabilized according to the wearing state of the cuff structure 20 each time blood pressure is measured.

[0066] Next, in step S108 of FIG. 4, the CPU 110 acts as a fluid containment control unit and switches the switching valve 34 to the rest position. Thereby, the pump 30 and the on-off valve 33 and the pressing cuff 23 and the first pressure sensor 31 are connected via the air pipes 38b, 38c, 38d, 38e, 38, 38a so that fluid can flow through them. At this time, the sensing cuff 21, together with the second pressure sensor 32, is disconnected from and sealed off from the pump 30 and the on-off valve 33. This rest position of the switching valve 34 is maintained from step S109 to step S115 in FIG. 4.

[0067] Next, the CPU 110 acts as a pressure control unit and turns on the pump 30 via the pump drive circuit 300 (step S109 in FIG. 4). Thereby, while maintaining the on-off valve 33 in the closed state, the pressurization of the pressure cuff 23 is started. In this pressurization process, as shown in FIG. 5A, the CPU 110 monitors the pressure (pressure cuff pressure) P1 of the pressure cuff 23 and the pressure (sensing cuff pressure) P2 of the sensing cuff 21 by the first pressure sensor 31 and the second pressure sensor 32, respectively. Further, the CPU 110 acts as a DC voltage acquisition unit, removes the pulse pressure wave (illustrated by reference numeral P1m in the enlarged elliptical region B in FIG. 5A) due to the volume change of the artery (radial artery 91, ulnar artery 92) passing through the left wrist 90 from the pressure cuff pressure P1, and extracts the DC voltage P1dc. Similarly, the CPU 110 acts as a DC voltage acquisition unit, removes the pulse pressure wave P2m due to the volume change of the artery (radial artery 91, ulnar artery 92) passing through the left wrist 90 from the sensing cuff pressure P2, and extracts the DC voltage P2dc. In this example, the CPU 110 acts as a pressure control unit and drives the pump 30 via the pump drive circuit 300 based on the DC voltage P1dc extracted from the pressure cuff pressure P1. Thereby, control is performed to send air to the pressure cuff 23 through the air pipes 38b, 38d, 38e, 38 in this order. Thereby, the pressure cuff 23 is inflated and gradually pressurized at a substantially constant pressurization rate to compress the left wrist 90.

[0068] During this pressurization process, the CPU 110 acts as a pulse wave amplitude acquisition unit, extracts a plethysmographic pulse wave P1m from the pressure cuff pressure P1, and acquires the amplitude of the plethysmographic pulse wave P1m (pulse wave amplitude) for each beat (denoted as i1, i2, i3, …) (step S110 in FIG. 4). It is assumed that beats have occurred even before i1 (the same applies hereinafter). In the elliptical region B in FIG. 5A, the pulse wave amplitudes acquired from the plethysmographic pulse wave P1m for each beat are exemplified by symbols A1, A2, A3, … (collectively denoted by the symbol A as appropriate). In this example, the pulse wave amplitude is defined as the pressure difference between the rising start point and the peak point for each beat of the plethysmographic pulse wave P1m. In this example, the CPU 110 associates the pulse wave amplitudes A1, A2, A3, … acquired from the plethysmographic pulse wave P1m for each beat i1, i2, i3, … with the DC voltages P2dc1, P2dc2, P2dc3, … extracted from the sensing cuff pressure P2 at the time points (denoted as t1, t2, t3, …) when the above beats i1, i2, i3, … of the plethysmographic pulse wave P1m occur, respectively, and regards each as a set of data. Then, as exemplified in Table 1 below, they are sequentially stored in the memory 51. (Table 1) TIFF2025077272000002.tif47145

[0069] In this example, the CPU 110 acts as a first blood pressure calculation unit and performs processing according to the following algorithm to calculate the blood pressure value. - As shown in FIG. 5B, a plane Q1 is set with the DC voltage P2dc extracted from the sensing cuff pressure P2 as the horizontal axis as the first axis and the pulse wave amplitude A acquired from the pressure cuff pressure P1 as the vertical axis as the second axis. Note that on this vertical axis, the maximum pulse wave amplitude (maximum peak) ENV1p among the pulse wave amplitudes A1, A2, A3, … is normalized to 1. On this plane Q1, during the above pressurization process, based on the data in Table 1, a plurality of data points D1, D2, D3, … formed by the DC voltages P2dc1, P2dc2, P2dc3, … extracted from the sensing cuff pressure P2 and the pulse wave amplitudes A1, A2, A3, … acquired from the pressure cuff pressure P1 are plotted. - Adjacent data points among the data points D1, D2, D3, … are connected by line segments to create a mountain-shaped envelope ENV1 (step S111 in FIG. 4). - For the maximum peak ENV1p of the mountain-shaped envelope line ENV1, the horizontal axis components of the points C1 and C2 where the low-pressure side portion ENV1a and the high-pressure side portion ENV1b cross the predetermined threshold values ThDBP and ThSBP with respect to the horizontal axis are obtained as the diastolic blood pressure value DBP1 and the systolic blood pressure value SBP1. In this example, ThDBP is set to 0.55 and ThSBP is set to 0.8.

[0070] In the actual process, in step S112 of FIG. 4, based on the envelope line ENV1 created at this time, an attempt is made to calculate the blood pressure values (diastolic blood pressure value DBP1, systolic blood pressure value SBP1).

[0071] At this time, if the blood pressure values cannot yet be calculated due to insufficient data (NO in step S113), the processes of steps S110 to S112 are repeated as long as the pressing cuff pressure P1 has not reached the upper limit pressure (predetermined, for example, as the systolic blood pressure value plus 40 mmHg at the previous measurement for safety).

[0072] When the blood pressure values can be calculated in this way (YES in step S113), the CPU 110 acts as a pressure control unit, stops the pump 30 (step S114), and opens the on-off valve 33 (step S115). Thereby, control is performed to exhaust the air in the pressing cuff 23 through the air pipes 38, 38e, 38d, 38c in this order. Subsequently, the CPU 110 switches the switching valve 34 to the operating position (step S116). Thereby, control is performed to exhaust the air in the sensing cuff 21 through the air pipes 39, 39f, 38d, 38c in this order. Finally, the CPU 110 displays the measurement result of the blood pressure value on the display 50 (step S117) and performs control to record the calculated blood pressure value in the memory 51 (step S118).

[0073] As described above, in the first example of the operation flow for the blood pressure monitor 1 to measure blood pressure, in order to calculate the blood pressure value by the oscillometric method, a mountain-shaped envelope line ENV1 is created on a plane Q1 (see FIG. 5B) with the DC voltage P2dc extracted from the sensing cuff pressure P2 on the horizontal axis and the pulse wave amplitude A obtained from the pressing cuff pressure P1 on the vertical axis. Then, the mountain-shaped envelope line ENV1 is created using data points D1, D2, D3,... including the pulse wave amplitudes A1, A2, A3,... obtained from the pressing cuff pressure P1 as the vertical axis direction components. Here, during the pressurization process, the pressing cuff 23 is in a state of being inflated by the pressurizing air, and moreover, it indirectly surrounds the left wrist 90 as the measurement site via the sensing cuff 21 and the back plate 22. Therefore, the pressing cuff 23 is less affected by the degree to which the tendon 96 passing through the left wrist 90 bulges and / or the degree of adhesion of the sensing cuff 21 to the left wrist 90. As a result, the tendon 96 is not divided (the air flow is blocked) in the circumferential direction Y surrounding the left wrist 90. Therefore, the pulse wave amplitude A obtained from the pressing cuff pressure P1 becomes stable as the vertical axis direction component of each data point. Therefore, according to this first example, the blood pressure value can be obtained stably.

[0074] (Second example of blood pressure measurement operation) FIG. 6 shows a second example of the operation flow for the blood pressure monitor 1 to measure blood pressure by the oscillometric method.

[0075] Depending on the degree to which the tendon 96 passing through the left wrist 90 as the measurement site bulges and / or the degree of adhesion of the sensing cuff 21 to the left wrist 90, in addition to the pressure pulse wave extracted from the sensing cuff pressure P2, it is also assumed that the DC voltage P2dc extracted from the sensing cuff pressure P2 becomes unstable. Therefore, in this second example (and the third and fourth examples described later), instead of the DC voltage P2dc extracted from the sensing cuff pressure P2, a converted DC voltage corresponding to that DC voltage P2dc is used on the horizontal axis.

[0076] Here, FIG. 7A shows a comparison of the pressing cuff pressure P1 and the sensing cuff pressure P2 during the pressurization process when the circumferential length of the left wrist 90 as the measurement site is small (14.4 cm in this example). FIG. 7B shows a comparison of the pressing cuff pressure P1 and the sensing cuff pressure P2 during the pressurization process when the circumferential length of the left wrist 90 as the measurement site is average (16.6 cm in this example). Further, FIG. 7C shows a comparison of the pressing cuff pressure P1 and the sensing cuff pressure P2 during the pressurization process when the circumferential length of the left wrist 90 as the measurement site is large (19.5 cm in this example). As can be seen from these figures, regardless of the circumferential length of the left wrist 90, there is a corresponding relationship where P1 > P2 between the pressing cuff pressure P1 and the sensing cuff pressure P2. In this specification, such a corresponding relationship between cuff pressures is referred to as the "corresponding relationship between cuff pressures". Such a corresponding relationship between cuff pressures occurs for the following reason. That is, generally in a blood pressure monitor cuff, in order for the internal pressure of the cuff to be equal to the pressure applied to the measurement site, a dimensional ratio is required such that the width direction dimension of the cuff is 1.2 times or more the diameter of the measurement site, or about 40% or more of the circumferential length of the measurement site. Here, as can be seen from the description of the width direction dimensions of the components of the cuff structure 20 described above, the pressing cuff 21 does not satisfy the requirement of the above dimensional ratio with respect to the left wrist 90 which is the measurement site. For this reason, the phenomenon occurs that the pressing cuff pressure P1 becomes larger than the sensing cuff pressure P2.

[0077] In this second example (and the third and fourth examples described later), on the premise that there is the above corresponding relationship between cuff pressures, instead of the DC voltage P2dc extracted from the sensing cuff pressure P2, the DC voltage P1dc extracted from the pressing cuff pressure P1 is converted and used as the DC voltage P2dc extracted from the sensing cuff pressure P2. In particular, in this second example, an approximate formula (referred to as Eq. 1) for converting the DC voltage P1dc extracted from the pressing cuff pressure P1 into the DC voltage P2dc extracted from the sensing cuff pressure P2 is created based on the corresponding relationship between cuff pressures over a predetermined first pressure range (lower limit 40 mmHg, upper limit 140 mmHg).

[0078] Specifically, in the operation flow shown in FIG. 6, from step S201 to step S209, the processing proceeds in exactly the same manner as in steps S101 to S109 of FIG. 4. In the pressurization process started at step S209, as shown in FIG. 8A, the CPU 110 monitors the pressure (pressing cuff pressure) P1 of the pressing cuff 23 and the pressure (sensing cuff pressure) P2 of the sensing cuff 21 by the first pressure sensor 31 and the second pressure sensor 32, respectively. Further, the CPU 110 acts as a DC voltage acquisition unit, removes the pulse wave P1m due to the volume change of the artery (radial artery 91, ulnar artery 92) passing through the left wrist 90 from the pressing cuff pressure P1, and extracts the DC voltage P1dc. Similarly, the CPU 110 acts as a DC voltage acquisition unit, removes the pulse wave P2m due to the volume change of the artery (radial artery 91, ulnar artery 92) passing through the left wrist 90 from the sensing cuff pressure P2, and extracts the DC voltage P2dc. In this example, the CPU 110 acts as a pressure control unit and drives the pump 30 via the pump drive circuit 300 based on the DC voltage P1dc extracted from the pressing cuff pressure P1. Thereby, control is performed to send air to the pressing cuff 23 through the air pipes 38b, 38d, 38e, 38 in this order. Thereby, the pressing cuff 23 is inflated and the pressure is gradually increased at a substantially constant pressurization rate to compress the left wrist 90.

[0079] In step S210 of FIG. 6, during this pressurization process, the CPU 110 acts as a pulse wave amplitude acquisition unit, extracts a plethysmogram P1m from the pressure cuff pressure P1, and acquires the amplitude of the plethysmogram P1m (pulse wave amplitude) for each beat (denoted as i1, i2, i3, …). In FIG. 8A, the pulse wave amplitudes acquired for each beat from the plethysmogram P1m are illustrated by reference signs A1, A2, A3, … (collectively denoted as reference sign A as appropriate). In this example, the CPU 110 associates the pulse wave amplitudes A1, A2, A3, … acquired from the plethysmogram P1m for each beat i1, i2, i3, … with the DC voltages P1dc1, P1dc2, P1dc3, … extracted from the pressure cuff pressure P1 at the time points (denoted as t1, t2, t3, …) when the above beats i1, i2, i3, … occur, and the DC voltages P2dc1, P2dc2, P2dc3, … extracted from the sensing cuff pressure P2 at the time points when the above beats i1, i2, i3, … occur, respectively, and regards each as a set of data. Then, as illustrated in Table 2 below, they are sequentially stored in the memory 51. (Table 2) TIFF2025077272000003.tif67146

[0080] Also, in step S211 of FIG. 6, the CPU 110 acts as a DC voltage acquisition unit and determines whether the current sensing cuff pressure P2 is 140 mmHg or more, which is the upper limit of the first pressure range. If the current sensing cuff pressure P2 is less than 140 mmHg (NO in step S211), the process returns to step S210 to continue acquiring the pulse wave amplitude A. If the current sensing cuff pressure P2 is 140 mmHg or more (YES in step S211) and the approximate formula Eq. 1 has not been created yet (NO in step S212), the CPU 110 acts as a DC voltage acquisition unit and creates an approximate formula Eq. 1 for converting the DC voltage P1dc extracted from the pressure cuff pressure P1 to the DC voltage P2dc extracted from the sensing cuff pressure P2 (step S213).

[0081] Specifically, as shown in FIG. 8B, the CPU 110 first approximates the change over time of the pressing cuff pressure P1 and the change over time of the sensing cuff pressure P2 on a plane with the horizontal axis being the time t and the vertical axis being the cuff pressure P, based on the data in Table 2. For example, assuming that a1, b1, a2, and b2 are constants, the approximate straight line L1 is represented by P = a1×t + b1, and the approximate straight line L2 is represented by P = a2×t + b2. Then, the approximate formula Eq. 1 for converting the DC voltage P1dc extracted from the pressing cuff pressure P1 into the DC voltage P2dc extracted from the sensing cuff pressure P2 is, assuming that the converted DC voltage is represented as f(P1dc), f(P1dc)=(P1dc - b1)÷a1×a2 + b2 …(Eq.1) is obtained as follows.

[0082] Here, the data range of the cuff pressure correspondence relationship used to obtain the approximate straight lines L1 and L2 is over the first pressure range (lower limit 40 mmHg, upper limit 140 mmHg). Conversely, it is not used for the range below 40 mmHg and the range above 140 mmHg. The reason for not using the range below 40 mmHg is that due to insufficient pressurization, the reliability of the data is low. The reason for not using the range above 140 mmHg is to avoid imposing an unnecessary physical burden on the user (especially users with a systolic blood pressure value of 140 mmHg or less).

[0083] Next, in step S214 of FIG. 6, the CPU 110 acts as a DC voltage acquisition unit and converts the DC voltages P1dc1, P1dc2, P1dc3,... extracted from the pressing cuff pressure P1 stored in the memory 51 (Table 2) into the DC voltages corresponding to the DC voltages P2dc extracted from the sensing cuff pressure P2 respectively by the approximate formula Eq. 1 (these are represented by the symbols f(P1dc)1, f(P1dc)2, f(P1dc)3,...). As a result, data as exemplified in the following Table 3 is stored in the memory 51. Note that Table 3 may be created integrally with the previous Table 2. (Table 3) TIFF2025077272000004.tif47147

[0084] In this example, the CPU 110 acts as a first blood pressure calculation unit and performs processing according to the following algorithm to calculate the blood pressure value. - As shown in FIG. 8C, a plane Q2 is set with the converted DC voltage f(P1dc) as the horizontal axis as the first axis and the pulse wave amplitude A obtained from the pressing cuff pressure P1 as the vertical axis as the second axis. Note that on this vertical axis, the maximum pulse wave amplitude (maximum peak) ENV2p among the pulse wave amplitudes A1, A2, A3,... is normalized to 1. On this plane Q2, during the pressurization process, based on the data in Table 3, a plurality of data points D11, D12, D13,... formed by the converted DC voltages f(P1dc)1, f(P1dc)2, f(P1dc)3,... and the pulse wave amplitudes A1, A2, A3,... obtained from the pressing cuff pressure P1 are plotted. - Adjacent data points among the data points D11, D12, D13,... are connected by line segments to create a mountain-shaped envelope ENV2 (step S215 in FIG. 6). - For the maximum peak ENV2p of the mountain-shaped envelope ENV2, the horizontal axis direction components of the points C11, C12 where the low-pressure side portion ENV2a and the high-pressure side portion ENV2b cross the predetermined threshold values ThDBP, ThSBP are obtained as the diastolic blood pressure value DBP2 and the systolic blood pressure value SBP2, respectively. Note that in this example, similar to the previous example, ThDBP is set to 0.55 and ThSBP is set to 0.8.

[0085] In the actual processing, in step S216 of FIG. 6, based on the envelope ENV2 created at this time, an attempt is made to calculate the blood pressure value (diastolic blood pressure value DBP2, systolic blood pressure value SBP2).

[0086] At this time, if the blood pressure value cannot yet be calculated due to insufficient data (NO in step S217), the processing of steps S210 to S216 is repeated as long as the pressing cuff pressure P1 has not reached the upper limit pressure (predetermined, for example, as the systolic blood pressure value plus 40 mmHg at the previous measurement for safety). However, if the approximate formula Eq. 1 has already been created (YES in step S212), step S213 is skipped.

[0087] When the blood pressure value has been calculated in this way (YES in step S217), the CPU 110 acts as a pressure control unit, stops the pump 30 (step S218), and opens the on-off valve 33 (step S219). Thereby, control is performed to exhaust the air in the pressing cuff 23 through the air pipes 38, 38e, 38d, 38c in this order. Subsequently, the CPU 110 switches the switching valve 34 to the operating position (step S220). Thereby, control is performed to exhaust the air in the sensing cuff 21 through the air pipes 39, 39f, 38d, 38c in this order. Finally, the CPU 110 displays the measurement result of the blood pressure value on the display 50 (step S221) and performs control to record the calculated blood pressure value in the memory 51 (step S222).

[0088] Thus, in the second example of the operation flow for the sphygmomanometer 1 to measure blood pressure, on a plane Q2 (see FIG. 8C) having the converted DC voltage f(P1dc) derived from the pressing cuff pressure P1 on the horizontal axis and the pulse wave amplitude A obtained from the pressing cuff pressure P1 on the vertical axis, a mountain-shaped envelope ENV2 is created. Here, as described above, the pressing cuff 23 is in a state of being inflated by the pressurized air, and moreover, indirectly surrounds the left wrist 90 as the measurement site via the sensing cuff 21 and the back plate 22. Therefore, the pressing cuff 23 is less affected by the degree to which the tendon 96 passing through the left wrist 90 bulges and / or the degree of adhesion of the sensing cuff 21 to the left wrist 90. As a result, the tendon 96 does not divide (block the air flow) in the circumferential direction Y surrounding the left wrist 90. Therefore, similar to the first example, the pulse wave amplitude A obtained from the pressing cuff pressure P1 becomes stable as the vertical axis direction component of each data point. Moreover, even if not only the pressure pulse wave extracted from the sensing cuff pressure P2 but also the DC voltage P2dc extracted from the sensing cuff pressure P2 is unstable, the converted DC voltage f(P1dc) becomes stable as the horizontal axis direction component of each data point. Therefore, according to this second example, the blood pressure value can be obtained more stably.

[0089] Moreover, in this second example, the above approximate formula Eq. 1 is created based on the correspondence relationship between cuff pressures over a predetermined first pressure range (lower limit 40 mmHg, upper limit 140 mmHg). In this case, for example, the process of setting a pressure range every time blood pressure is measured is unnecessary, and the overall process becomes simple.

[0090] FIG. 9A shows a comparison between the diastolic blood pressure value DBP2 and the systolic blood pressure value SBP2 obtained by the operation flow of the second example of the sphygmomanometer 1 and the diastolic blood pressure value DBP2ref and the systolic blood pressure value SBP2ref obtained by the reference auscultation method. As can be seen from this FIG. 9A, the diastolic blood pressure value DBP2 and the systolic blood pressure value SBP2 obtained by the operation flow of the second example coincide with the diastolic blood pressure value DBP2ref and the systolic blood pressure value SBP2ref obtained by the auscultation method, respectively. On the other hand, FIG. 9B shows a comparison between the diastolic blood pressure value DBP0 and the systolic blood pressure value SBP0 obtained by the sphygmomanometer of the conventional example and the diastolic blood pressure value DBP0ref and the systolic blood pressure value SBP0ref obtained by the reference auscultation method. In the sphygmomanometer of the conventional example, as shown in FIG. 9B, on a plane Q0 having the DC voltage P2dc extracted from the sensing cuff pressure P2 as the horizontal axis and the pulse wave amplitude A0 obtained from the sensing cuff pressure P2 as the vertical axis, a plurality of data points D01, D02, D03,... formed by the DC voltage P2dc and the pulse wave amplitude A0 are plotted, and adjacent data points among the data points D01, D02, D03,... are connected by line segments to create a mountain-shaped envelope ENV0. Further, with respect to the maximum peak ENV0p of the mountain-shaped envelope ENV0, the horizontal axis direction components of the points C01 and C02 where the low-pressure side portion ENV0a and the high-pressure side portion ENV0b cross the predetermined thresholds ThDBP and ThSBP are obtained as the diastolic blood pressure value DBP0 and the systolic blood pressure value SBP0, respectively. As can be seen from this FIG. 9B, the diastolic blood pressure value DBP0 and the systolic blood pressure value SBP0 obtained by the sphygmomanometer of the conventional example are shifted upward with respect to the diastolic blood pressure value DBP0ref and the systolic blood pressure value SBP0ref obtained by the auscultation method. This is presumably because the pressure pulse wave P2dc extracted from the sensing cuff pressure P2 becomes unstable and two peaks ENV0p and ENV0p1 are generated in the envelope ENV0. On the other hand, according to the sphygmomanometer 1, such a plurality of peaks do not occur. As a result, it has been verified that the sphygmomanometer 1 can stably obtain blood pressure values.

[0091] (Third Example of Blood Pressure Measurement Operation) FIG. 10 shows a third example of the operation flow in which the sphygmomanometer 1 measures blood pressure by the oscillometric method.

[0092] In this third example, similar to the first and second examples, the pulse wave amplitude A obtained from the pressing cuff pressure P1 is used as the vertical axis of the plane Q2 (see FIG. 8C) for creating the mountain-shaped envelope. Also, similar to the second example, the converted DC voltage derived from the pressing cuff pressure P1 is used as the horizontal axis of the plane Q2. The difference between this third example and the second example is that the approximate formula (referred to as Eq. 2) for converting the DC voltage P1dc extracted from the pressing cuff pressure P1 to the DC voltage P2dc extracted from the sensing cuff pressure P2 is not obtained based on the cuff pressure correspondence relationship over a predetermined first pressure range (lower limit 40 mmHg, upper limit 140 mmHg), but is obtained based on the cuff pressure correspondence relationship over a second pressure range from a predetermined lower pressure value (40 mmHg) to the maximum pressurization value corresponding to the provisional systolic blood pressure value.

[0093] Specifically, in the operation flow shown in FIG. 10, from step S301 to step S309, the processing proceeds in exactly the same manner as in steps S201 to S209 of FIG. 6. In the pressurization process started at step S309, the CPU 110 monitors the pressure (pressing cuff pressure) P1 of the pressing cuff 23 and the pressure (sensing cuff pressure) P2 of the sensing cuff 21 by the first pressure sensor 31 and the second pressure sensor 32, respectively, in the same manner as shown in FIG. 8A. Further, the CPU 110 acts as a DC voltage acquisition unit, removes the pulse wave P1m due to the volume change of the artery (radial artery 91, ulnar artery 92) passing through the left wrist 90 from the pressing cuff pressure P1, and extracts the DC voltage P1dc. Similarly, the CPU 110 acts as a DC voltage acquisition unit, removes the pulse wave P2m due to the volume change of the artery (radial artery 91, ulnar artery 92) passing through the left wrist 90 from the sensing cuff pressure P2, and extracts the DC voltage P2dc. In this example, the CPU 110 acts as a pressure control unit and drives the pump 30 via the pump drive circuit 300 based on the DC voltage P1dc extracted from the pressing cuff pressure P1. Thereby, control is performed to send air to the pressing cuff 23 through the air pipes 38b, 38d, 38e, 38 in this order. Thereby, the pressing cuff 23 is inflated and the pressure is gradually increased at a substantially constant pressurization rate to compress the left wrist 90. At this time, the back plate 22 transmits the pressing force from the pressing cuff 23 to the sensing cuff 21.

[0094] In step S310 of FIG. 10, in this pressurization process, the CPU 110 acts as a pulse wave amplitude acquisition unit, extracts the pulse wave P1m from the pressing cuff pressure P1, and acquires the amplitude of the pulse wave P1m (pulse wave amplitude) for each beat (denoted as i1, i2, i3,...). In this example, the CPU 110 associates the pulse wave amplitudes A1, A2, A3,... acquired for each beat i1, i2, i3,... from the pulse wave P1m, the DC voltages P1dc1, P1dc2, P1dc3,... extracted from the pressing cuff pressure P1 at the time points (denoted as t1, t2, t3,...) when the beats i1, i2, i3,... occur, and the DC voltages P2dc1, P2dc2, P2dc3,... extracted from the sensing cuff pressure P2 at the time points when the beats i1, i2, i3,... occur, respectively, and regards each as a set of data. Then, as exemplified in Table 2 above, it is sequentially stored in the memory 51.

[0095] At the same time, in step S311, the CPU 110 extracts a plethysmogram P2m (see FIG. 8A) from the sensing cuff pressure P2, and acquires the amplitude of the plethysmogram P2m (pulse wave amplitude) for each beat (denoted as i1, i2, i3,...). In FIG. 8A, the pulse wave amplitudes acquired for each beat from the plethysmogram P2m are illustrated by reference signs A01, A02, A03,... (collectively denoted as reference sign A0 as appropriate). In this example, the CPU 110 associates the pulse wave amplitudes A01, A02, A03,... acquired for each beat i1, i2, i3,... from the plethysmogram P2m with the DC pressures P2dc1, P2dc2, P2dc3,... extracted from the sensing cuff pressure P2 at the time when the beats i1, i2, i3,... occur, respectively, and regards each as a set of data. Then, as illustrated in Table 4 below, the data is sequentially stored in the memory 51. Note that Table 4 may be created integrally with Table 2 above. (Table 4) TIFF2025077272000005.tif47145

[0096] In this example, in step S312 of FIG. 10, the CPU 110 acts as a second blood pressure calculation unit and performs processing according to the same algorithm as the algorithm in the conventional blood pressure monitor in order to calculate a provisional blood pressure value by the oscillometric method. For simplicity, the description will be made again with reference to FIG. 9B. - As shown in FIG. 9B, a plane Q0 is set with the horizontal axis having the DC pressure P2dc extracted from the sensing cuff pressure P2 as the first axis and the vertical axis having the pulse wave amplitude A0 acquired from the sensing cuff pressure P2 as the second axis. Note that on this vertical axis, the maximum pulse wave amplitude (maximum peak) ENV0p among the pulse wave amplitudes A01, A02, A03,... is normalized to 1. On this plane Q0, in the pressurization process, based on the data in Table 4, a plurality of data points D01, D02, D03,... formed by the DC pressures P2dc1, P2dc2, P2dc,... extracted from the sensing cuff pressure P2 and the pulse wave amplitudes A01, A02, A03,... acquired from the sensing cuff pressure P2 are plotted. - The adjacent data points among the data points D01, D02, D03,... are connected by line segments to create a mountain-shaped envelope ENV0. - For the maximum peak ENV0p of the mountain-shaped envelope line ENV0, the horizontal axis direction components of the points C1 and C2 where the low-pressure side part ENV0a and the high-pressure side part ENV0b cross the preset threshold values ThDBP and ThSBP with respect to the horizontal axis are obtained as the provisional diastolic blood pressure value DBP0 and the provisional systolic blood pressure value SBP0. In this example, ThDBP is set to 0.55 and ThSBP is set to 0.8.

[0097] In the actual process, in step S312 of FIG. 10, based on the envelope line ENV0 created at this time, an attempt is made to calculate the provisional blood pressure values (provisional diastolic blood pressure value DBP0, provisional systolic blood pressure value SBP0).

[0098] At this time, if the provisional blood pressure values cannot be calculated yet due to insufficient data (NO in step S313), the processes of steps S310 to S312 are repeated as long as the pressing cuff pressure P1 has not reached the upper limit pressure (predetermined for safety, for example, the systolic blood pressure value at the previous measurement plus 40 mmHg).

[0099] When the provisional blood pressure values can be calculated in this way (YES in step S313), the CPU 110 stores the provisional blood pressure values (especially the provisional systolic blood pressure value SBP0) in the memory 51. Subsequently, the CPU 110 acts as a pressure control unit, stops the pump 30 (step S314), and opens the on-off valve 33 (step S315). Thereby, control is performed to exhaust the air in the pressing cuff 23 through the air pipes 38, 38e, 38d, 38c in this order. Subsequently, the CPU 110 switches the switching valve 34 to the operating position (step S316). Thereby, control is performed to exhaust the air in the sensing cuff 21 through the air pipes 39, 39f, 38d, 38c in this order.

[0100] Next, in step S317 of FIG. 10, the CPU 110 acts as a DC voltage acquisition unit and creates an approximate formula Eq. 2 for converting the DC voltage P1dc extracted from the pressing cuff pressure P1 into the DC voltage P2dc extracted from the sensing cuff pressure P2.

[0101] Specifically, as shown in FIG. 8B, the CPU 110 first approximates the change over time of the pressing cuff pressure P1 and the change over time of the sensing cuff pressure P2 on a plane with the horizontal axis being the time t and the vertical axis being the cuff pressure P based on the data in Table 2. An approximate straight line (denoted as L1′) for the change over time of the pressing cuff pressure P1 and an approximate straight line (denoted as L2′) for the change over time of the sensing cuff pressure P2 are obtained. For example, assuming a1′, b1′, a2′, and b2′ are constants, the approximate straight line L1′ is represented by P = a1′×t + b1′, and the approximate straight line L2′ is represented by P = a2′×t + b2′. Then, the approximate formula Eq. 2 for converting the DC voltage P1dc extracted from the pressing cuff pressure P1 to the DC voltage P2dc extracted from the sensing cuff pressure P2 is, assuming the converted DC voltage is represented as g(P1dc), g(P1dc)=(P1dc - b1′)÷a1′×a2′ + b2′ …(Eq.2) is obtained as follows.

[0102] Here, in this third example, the data range of the cuff pressure correspondence relationship used to obtain the approximate straight lines L1′ and L2′ is over the second pressure interval from a predetermined lower pressure value of 40 mmHg to the maximum pressurization value corresponding to the temporary systolic blood pressure value SBP0. Conversely, the ranges less than 40 mmHg and exceeding the above maximum pressurization value are not used. The reason for not using the range less than 40 mmHg is that due to insufficient pressurization, the reliability of the data is low. The reason for not using the range exceeding the above maximum pressurization value is to avoid imposing an unnecessary physical burden on the user.

[0103] Next, in step S318 of FIG. 10, the CPU 110 acts as a DC voltage acquisition unit and converts the DC voltages P1dc1, P1dc2, P1dc3,... extracted from the pressing cuff pressure P1 stored in the memory 51 (Table 2) into DC voltages corresponding to the DC voltages P2dc extracted from the sensing cuff pressure P2 respectively by the approximate formula Eq. 2 (these are denoted as g(P1dc)1, g(P1dc)2, g(P1dc)3,...). As a result, data as exemplified in the following Table 5 is stored in the memory 51. Note that Table 5 may be created integrally with the previous Table 2. (Table 5) TIFF2025077272000006.tif47147

[0104] Next, the CPU 110 acts as a first blood pressure calculation unit and performs processing according to the following algorithm to calculate the blood pressure value. Here, for simplicity, it is assumed that the "f(P1dc)" on the horizontal axis in FIG. 8C is read as "g(P1dc)", and FIG. 8C will be used for explanation again. - As shown in FIG. 8C, a plane Q2 is set with the converted DC voltage g(P1dc) as the horizontal axis as the first axis and the pulse wave amplitude A obtained from the pressing cuff pressure P1 as the vertical axis as the second axis. On this plane Q2, during the pressurization process, based on the data in Table 5, a plurality of data points D11, D12, D13,... formed by the converted DC voltages g(P1dc)1, g(P1dc)2, g(P1dc)3,... and the pulse wave amplitudes A1, A2, A3,... obtained from the pressing cuff pressure P1 are plotted. - Connect adjacent data points among the data points D11, D12, D13,... with line segments to create a mountain-shaped envelope ENV2 (step S319 in FIG. 10). - For the maximum peak ENV2p of the mountain-shaped envelope ENV2, the horizontal axis direction components of the points C11, C12 where the low-pressure side part ENV2a and the high-pressure side part ENV2b cross the predetermined thresholds ThDBP, ThSBP with respect to the horizontal axis are obtained as the diastolic blood pressure value DBP2 and the systolic blood pressure value SBP2, respectively (step S320 in FIG. 10). In this example, similar to the previous example, ThDBP is set to 0.55 and ThSBP is set to 0.8.

[0105] After that, the CPU 110 displays the measurement result of the blood pressure value on the display 50 (step S321) and also performs control to record the calculated blood pressure value in the memory 51 (step S322).

[0106] Thus, in the third example of the operation flow in which the sphygmomanometer 1 measures blood pressure, on a plane Q2 (see FIG. 8C) with the converted DC voltage g(P1dc) derived from the pressing cuff pressure P1 on the horizontal axis and the pulse wave amplitude A obtained from the pressing cuff pressure P1 on the vertical axis, a mountain-shaped envelope ENV2 is created. Here, as described above, the pressing cuff 23 is in a state of being inflated by pressurized air, and indirectly surrounds the left wrist 90 as the measurement site via the sensing cuff 21 and the back plate 22. Therefore, the pressing cuff 23 is less affected by the degree to which the tendon 96 passing through the left wrist 90 bulges and / or the degree of adhesion of the sensing cuff 21 to the left wrist 90. As a result, the tendon 96 does not interrupt (block the air flow) in the circumferential direction Y surrounding the left wrist 90. Therefore, similar to the first and second examples, the pulse wave amplitude A obtained from the pressing cuff pressure P1 becomes stable as the vertical axis direction component of each data point. Moreover, even if not only the pressure pulse wave extracted from the sensing cuff pressure P2 but also the DC voltage P2dc extracted from the sensing cuff pressure P2 is unstable, the converted DC voltage g(P1dc) becomes stable as the horizontal axis direction component of each data point. Therefore, according to this third example, the blood pressure value can be obtained more stably.

[0107] Moreover, in this third example, the approximate formula Eq. 2 is created based on the correspondence relationship between cuff pressures over a second pressure interval from a predetermined lower pressure value to the maximum pressurization value corresponding to the provisional systolic blood pressure value. Therefore, for example, if the user's systolic blood pressure value is relatively low (for example, about 110 mmHg), the maximum pressurization value also becomes correspondingly low, and the second pressure interval can be set as an interval from about 40 mmHg to about 110 mmHg, for example. In such a case, compared with the second example, the time and physical burden for the user's blood pressure measurement can be reduced.

[0108] Note that in this third example, the CPU 110 acts as the second blood pressure calculation unit and calculates the above provisional blood pressure value according to the same algorithm as the algorithm in the sphygmomanometer of the above conventional example by the oscillometric method. However, it is not limited to this. The CPU 110 may act as the second blood pressure calculation unit and calculate the above provisional blood pressure value according to the same algorithm as in the first example. That is, - Set a plane Q1 (see FIG. 5B) including the DC voltage P2dc extracted from the sensing cuff pressure P2 as the horizontal axis with the first axis and the pulse wave amplitude A obtained from the pressing cuff pressure P1 as the vertical axis with the second axis. On this plane Q1, based on the data in Table 1, plot a plurality of data points D1, D2, D3,... formed by the DC voltage P2dc extracted from the sensing cuff pressure P2 and the pulse wave amplitudes A1, A2, A3,... obtained from the pressing cuff pressure P1. - Connect adjacent data points among the data points D1, D2, D3,... with line segments to create a mountain-shaped envelope ENV1. - For the maximum peak ENV1p of the mountain-shaped envelope ENV1, obtain the horizontal axis direction components of the points C1 and C2 where the low-pressure side portion ENV1a and the high-pressure side portion ENV1b cross the predetermined threshold values ThDBP and ThSBP with respect to the horizontal axis as the diastolic blood pressure value DBP1 and the systolic blood pressure value SBP1, respectively.

[0109] In this way, the above provisional blood pressure value may be calculated. In that case, the process of extracting the pressure pulse wave P2m from the sensing cuff pressure P2 (step S311 in FIG. 10) can be omitted, and the process becomes simple. Also, the above provisional blood pressure value can be stably obtained.

[0110] (Fourth Example of Blood Pressure Measurement Operation) FIG. 11 shows a fourth example of the operation flow of the sphygmomanometer 1 for measuring blood pressure by the oscillometric method.

[0111] In this fourth example, similar to the first to third examples, the pulse wave amplitude A obtained from the pressing cuff pressure P1 is used as the vertical axis of the plane Q2 (see FIG. 8C) for creating the mountain-shaped envelope. Also, similar to the second and third examples, the converted DC voltage derived from the pressing cuff pressure P1 is used as the horizontal axis of the plane Q2. What this fourth example differs from the second and third examples is that an approximation formula (referred to as Eq. 3 here) for converting the DC voltage P1dc extracted from the pressing cuff pressure P1 to the DC voltage P2dc extracted from the sensing cuff pressure P2 is obtained based on the cuff pressure correspondence relationship over the third pressure interval corresponding to the past diastolic blood pressure value and systolic blood pressure value stored in the memory 51. Assume that the memory 51 stores 80 mmHg and 120 mmHg as the past (in this example, the previous) diastolic blood pressure value and systolic blood pressure value, respectively.

[0112] Specifically, in the operation flow shown in FIG. 11, from step S401 to step S402, the processing proceeds in exactly the same manner as from step S201 to step S202 in FIG. 6. In step S403 of FIG. 11, the CPU 110 reads 80 mmHg and 120 mmHg as the previous diastolic blood pressure value and systolic blood pressure value, respectively, in this example. Also, from step S404 to step S410 in FIG. 11, the processing proceeds in exactly the same manner as from step S203 to step S209 in FIG. 6.

[0113] In the pressurization process started in step S410 of FIG. 11, the CPU 110 monitors the pressure (pressing cuff pressure) P1 of the pressing cuff 23 and the pressure (sensing cuff pressure) P2 of the sensing cuff 21 by the first pressure sensor 31 and the second pressure sensor 32, respectively, in the same manner as shown in FIG. 8A. Further, the CPU 110 acts as a DC voltage acquisition unit, removes the pulse wave P1m due to the volume change of the arteries (radial artery 91, ulnar artery 92) passing through the left wrist 90 from the pressing cuff pressure P1, and extracts the DC voltage P1dc. Similarly, the CPU 110 acts as a DC voltage acquisition unit, removes the pulse wave P2m due to the volume change of the arteries (radial artery 91, ulnar artery 92) passing through the left wrist 90 from the sensing cuff pressure P2, and extracts the DC voltage P2dc. In this example, the CPU 110 acts as a pressure control unit and drives the pump 30 via the pump drive circuit 300 based on the DC voltage P1dc extracted from the pressing cuff pressure P1. Thereby, control is performed to send air to the pressing cuff 23 through the air pipes 38b, 38d, 38e, 38 in this order. Thereby, the pressing cuff 23 is inflated and the pressure is gradually increased at a substantially constant pressurization rate to compress the left wrist 90. At this time, the back plate 22 transmits the pressing force from the pressing cuff 23 to the sensing cuff 21.

[0114] In step S411 of FIG. 11, in this pressurization process, the CPU 110 acts as a pulse wave amplitude acquisition unit, extracts the pulse wave P1m from the pressing cuff pressure P1, and acquires the amplitude of the pulse wave P1m (pulse wave amplitude) for each beat (denoted as i1, i2, i3,...). In this example, the CPU 110 associates the pulse wave amplitudes A1, A2, A3,... acquired for each beat i1, i2, i3,... from the pulse wave P1m, the DC voltages P1dc1, P1dc2, P1dc3,... extracted from the pressing cuff pressure P1 at the time points (denoted as t1, t2, t3,...) when the beats i1, i2, i3,... occurred, and the DC voltages P2dc1, P2dc2, P2dc3,... extracted from the sensing cuff pressure P2 at the time points when the beats i1, i2, i3,... occurred, respectively, and regards each as a set of data. Then, as exemplified in Table 2 above, it is sequentially stored in the memory 51.

[0115] Also, in step S412 of FIG. 11, the CPU 110 acts as a DC voltage acquisition unit to determine whether the current sensed cuff pressure P2 is equal to or higher than the previous systolic blood pressure value (in this example, 120 mmHg) as the upper limit of the third pressure range. If the current sensed cuff pressure P2 is less than 120 mmHg (NO in step S412), the process returns to step S411 to continue acquiring the pulse wave amplitude A. If the current sensed cuff pressure P2 is 120 mmHg or higher (YES in step S412) and the approximate equation Eq. 3 has not been created yet (NO in step S413), the CPU 110 acts as a DC voltage acquisition unit to create an approximate equation Eq. 3 for converting the DC voltage P1dc extracted from the pressing cuff pressure P1 to the DC voltage P2dc extracted from the sensed cuff pressure P2 (step S414).

[0116] Specifically, as shown in FIG. 8B, first, based on the data in Table 2, the CPU 110 obtains an approximate straight line (represented as L1″) approximating the change over time of the pressing cuff pressure P1 and an approximate straight line (represented as L2″) approximating the change over time of the sensed cuff pressure P2 on a plane with the time t on the horizontal axis and the cuff pressure P on the vertical axis. For example, assuming that the approximate straight line L1″ is represented by P = a1″×t + b1″ and the approximate straight line L2″ is represented by P = a2″×t + b2″ with a1″, b1″, a2″, and b2″ being constants. Then, the approximate equation Eq. 3 for converting the DC voltage P1dc extracted from the pressing cuff pressure P1 to the DC voltage P2dc extracted from the sensed cuff pressure P2, assuming the converted DC voltage is represented as h(P1dc), h(P1dc)=(P1dc - b1″)÷a1″×a2″+b2″ …(Eq.3) is obtained as follows.

[0117] Here, the data range of the cuff pressure correspondence relationship used to obtain the approximate straight lines L1″ and L2″ shall cover the third pressure interval (in this example, the lower limit is 80 mmHg and the upper limit is 120 mmHg) corresponding to the previous diastolic blood pressure value and systolic blood pressure value. Conversely, it shall not be used for the ranges below 80 mmHg and above 120 mmHg. The reason for not using the ranges below 80 mmHg and above 120 mmHg is to reduce the time and physical burden on the user for blood pressure measurement.

[0118] Next, in step S415 of FIG. 11, the CPU 110 acts as a DC voltage acquisition unit, and converts the DC voltages P1dc1, P1dc2, P1dc3,... extracted from the pressing cuff pressure P1 stored in the memory 51 (Table 2) into DC voltages (represented by these symbols h(P1dc)1, h(P1dc)2, h(P1dc)3,...) corresponding to the DC voltage P2dc extracted from the sensing cuff pressure P2 respectively, according to the approximate formula Eq. 3. As a result, data as exemplified in the following Table 6 is stored in the memory 51. Note that Table 6 may be created integrally with the previous Table 2. (Table 6) TIFF2025077272000007.tif41131

[0119] In this example, the CPU 110 acts as a first blood pressure calculation unit and performs processing according to the following algorithm to calculate the blood pressure value. Here, for simplicity, FIG. 8C will be used for explanation again by re-reading the "f(P1dc)" on the horizontal axis in FIG. 8C as "h(P1dc)". - As shown in FIG. 8C, a plane Q2 is set with the converted DC voltage h(P1dc) as the horizontal axis as the first axis and the pulse wave amplitude A obtained from the pressing cuff pressure P1 as the vertical axis as the second axis. On this plane Q2, during the pressurization process, based on the data in Table 6, a plurality of data points D11, D12, D13,... formed by the converted DC voltages h(P1dc)1, h(P1dc)2, h(P1dc)3,... and the pulse wave amplitudes A1, A2, A3,... obtained from the pressing cuff pressure P1 are plotted. - Connect adjacent data points among the data points D11, D12, D13, … with line segments to create a mountain-shaped envelope line ENV2 (step S416 in FIG. 11). - For the maximum peak ENV2p of the mountain-shaped envelope line ENV2, obtain the horizontal axis direction components of the points C11 and C12 where the low-pressure side portion ENV2a and the high-pressure side portion ENV2b cross the predetermined threshold values ThDBP and ThSBP with respect to the horizontal axis as the diastolic blood pressure value DBP2 and the systolic blood pressure value SBP2. In this example, as in the previous example, ThDBP is set to 0.55 and ThSBP is set to 0.8.

[0120] In the actual process, in step S417 of FIG. 11, an attempt is made to calculate the blood pressure values (diastolic blood pressure value DBP2, systolic blood pressure value SBP2) based on the envelope line ENV2 created at this time.

[0121] At this time, if the blood pressure values cannot yet be calculated due to insufficient data (NO in step S418), the processes of steps S411 to S417 are repeated as long as the pressing cuff pressure P1 has not reached the upper limit pressure (predetermined for safety, for example, the systolic blood pressure value at the previous measurement plus 40 mmHg). However, if the approximate formula Eq. 3 has already been created (YES in step S413), step S414 is skipped.

[0122] When the blood pressure values can be calculated in this way (YES in step S418), the CPU 110 acts as a pressure control unit, stops the pump 30 (step S419), and opens the on-off valve 33 (step S420). Thereby, control is performed to exhaust the air in the pressing cuff 23 through the air pipes 38, 38e, 38d, 38c in this order. Subsequently, the CPU 110 switches the switching valve 34 to the operating position (step S421). Thereby, control is performed to exhaust the air in the sensing cuff 21 through the air pipes 39, 39f, 38d, 38c in this order. And finally, the CPU 110 displays the measurement result of the blood pressure value on the display 50 (step S422) and performs control to record the calculated blood pressure value in the memory 51 (step S423).

[0123] Thus, in the fourth example of the operation flow in which the sphygmomanometer 1 measures blood pressure, on a plane Q2 (see FIG. 8C) having the converted DC voltage h(P1dc) derived from the pressing cuff pressure P1 on the horizontal axis and the pulse wave amplitude A obtained from the pressing cuff pressure P1 on the vertical axis, a mountain-shaped envelope ENV2 is created. Here, as described above, the pressing cuff 23 is in a state of being inflated by pressurized air, and moreover, indirectly surrounds the left wrist 90 as the measurement site via the sensing cuff 21 and the back plate 22. Therefore, the pressing cuff 23 is less affected by the degree to which the tendon 96 passing through the left wrist 90 bulges and / or the degree of adhesion of the sensing cuff 21 to the left wrist 90. As a result, the tendon 96 is not interrupted (the air flow is blocked) in the circumferential direction Y surrounding the left wrist 90. Therefore, similar to the first to third examples, the pulse wave amplitude A obtained from the pressing cuff pressure P1 becomes stable as the longitudinal axis direction component of each data point. Moreover, even if not only the pressure pulse wave extracted from the sensing cuff pressure P2 but also the DC voltage 1P2dc extracted from the sensing cuff pressure P2 is unstable, the converted DC voltage h(P1dc) becomes stable as the horizontal axis direction component of each data point. Therefore, according to this fourth example, the blood pressure value can be obtained more stably.

[0124] Moreover, in this fourth example, the approximate formula Eq. 3 is created based on the correspondence relationship between cuff pressures over the third pressure interval corresponding to the previous diastolic blood pressure value and systolic blood pressure value. In this case, the pressure interval can be set according to the user's previous diastolic blood pressure value and systolic blood pressure value. In other words, the process of setting the pressure interval in the current blood pressure measurement becomes unnecessary. For example, compared with the above-described third example, the process for calculating the provisional blood pressure value becomes unnecessary, and the overall process becomes simple. Therefore, the time and physical burden on the user for blood pressure measurement can be reduced.

[0125] In this fourth example, the past diastolic blood pressure value and systolic blood pressure value are assumed to be the previous diastolic blood pressure value and systolic blood pressure value. However, it is not limited to this. The past diastolic blood pressure value and systolic blood pressure value may be, for example, the average diastolic blood pressure value and systolic blood pressure value obtained by averaging the diastolic blood pressure values and systolic blood pressure values of a plurality of times (for example, including the previous time and the time before the previous time). In this case, for example, even if the previous diastolic blood pressure value and systolic blood pressure value are specifically low or high due to some abnormality, the influence of the abnormality can be mitigated and the third pressure interval can be appropriately set.

[0126] Note that in the above-described first to fourth examples, blood pressure calculation was performed during the pressurization process of the pressing cuff 23, but it is not limited to this. Blood pressure calculation may be performed during the decompression process. In that case, the pressing cuff 23 is once pressurized until the arteries (radial artery 91, ulnar artery 92) passing through the left wrist 90 are blocked, and the pressure of the pressing cuff 23 is gradually decompressed at a substantially constant decompression rate. During the decompression process, the CPU 110 functions as a DC voltage acquisition unit, a pulse wave amplitude acquisition unit, and a first blood pressure calculation unit to obtain a diastolic blood pressure value and a systolic blood pressure value.

[0127] Also, in the above-described first to fourth examples, air as a fluid for pressure transmission is accommodated in the sensing cuff 21 each time blood pressure is measured, and is exhausted after the measurement is completed, but it is not limited to this. The fluid for pressure transmission may be accommodated in the sensing cuff 21 at the manufacturing stage of this blood pressure monitor 1 and sealed.

[0128] Also, in the above-described first, second, and fourth examples, the sensing cuff 21 as the second cuff does not have to be disposed across the artery passing portion 90a of the left wrist 90, and the sensing cuff 21 may be disposed outside the artery passing portion 90a between the left wrist 90 and the pressing cuff 23. The reason is that in the first, second, and fourth examples, for the sensing cuff 21, it is sufficient if the DC voltage P2dc can be extracted from the sensing cuff pressure P2, and it is not necessary to extract the pulse wave P2m. When the sensing cuff 21 is disposed outside the artery passing portion 90a, the pulse wave due to the volume change of the artery (radial artery 91, ulnar artery 92) passing through the left wrist 90 is mainly directly transmitted to the pressing cuff 23.

[0129] In the above-described embodiment, the example in which the sensing cuff 21 is in direct contact with the left wrist 90 as the measurement site has been described, but the present invention is not limited to this. The sensing cuff 21 may be indirectly in contact with the left wrist 90 via another member (for example, a cover member).

[0130] In the above-described embodiment, the measurement site where the blood pressure monitor is attached is the left wrist 90, but the present invention is not limited to this. The blood pressure monitor of the present invention may be configured to be mirror-symmetric with respect to the blood pressure monitor 1 shown in FIG. 1 and attached to the right wrist. Further, the measurement site may be a site other than the wrist, such as the upper arm or lower limb.

[0131] Also, in the above-described embodiment, the main body 10 and the belt 2 are formed separately from each other, and the belt 2 is attached to the main body 10. However, the present invention is not limited to this. The main body 10 and the belt 2 may be integrally formed.

[0132] Also, in the above-described embodiment, the first belt portion 3 and the second belt portion 4 of the belt 2 are fastened or released by the lock 5. However, the present invention is not limited to this. For example, the first belt portion 3 and the second belt portion 4 may be connected to each other via an openable and closable three-fold buckle.

[0133] In the above-described embodiment, in order to calculate blood pressure, a mountain-shaped envelope line ENV1 (or ENV2) is created, threshold values ThDBP and ThSBP are set for the mountain-shaped envelope line ENV1 (or ENV2), and the diastolic blood pressure value DBP1 (or DBP2) and the systolic blood pressure value SBP1 (or SBP2) are obtained using such an algorithm. However, it is not limited to this. As an algorithm for calculating blood pressure, other algorithms may be used.

[0134] The above embodiments are examples, and various modifications are possible without departing from the scope of the present invention. The above-described multiple embodiments can each stand alone, but combinations of the embodiments are also possible. Also, various features in different embodiments can each stand alone, but combinations of features in different embodiments are also possible.

Explanation of Reference Numerals

[0135] 1 Sphygmomanometer 2 Belt 3 First Belt Portion 4 Second Belt Portion 10 Main Body 20 Cuff Structure 21 Sensing Cuff 22 Back Plate 23 Pressing Cuff 24 Curler 30 Pump 31 First Pressure Sensor 32 Second Pressure Sensor 33 On-Off Valve 34 Switching Valve 110 CPU

Claims

1. An electronic blood pressure meter configured to measure blood pressure by an oscillometric method based on a pressure pulse wave caused by a volume change of an artery passing through a measurement site, a bag-shaped first cuff configured to extend along a circumferential direction of the measurement site in order to receive a supply of pressurizing fluid and pressurize the measurement site; a second cuff configured in a bag shape capable of accommodating a fluid for pressure transmission and disposed along an inner circumferential surface of the first cuff; a first pressure sensor that detects a first cuff pressure, which is the pressure of the first cuff; a second pressure sensor that detects a second cuff pressure, which is the pressure of the second cuff; a pressure control unit that supplies the pressurizing fluid to the first cuff to pressurize it, or discharges the pressurizing fluid from the first cuff to reduce the pressure; Equipped with a DC pressure acquisition unit that acquires a DC pressure extracted from the second cuff pressure detected by the second pressure sensor or a converted DC pressure equivalent to the extracted DC pressure during a pressurization process in which the pressurization fluid is supplied to the first cuff by the pressure control unit or a depressurization process in which the pressurization fluid is discharged from the first cuff, with the first and second cuffs being attached together around the measurement site and the pressure transmission fluid being contained in the second cuff; a pulse wave amplitude acquisition unit that extracts the pressure pulse wave transmitted from the measurement site to the first cuff from the first cuff pressure detected by the first pressure sensor during the pressurization process or the depressurization process, and acquires the amplitude of the pressure pulse wave; A first blood pressure calculation unit, The first blood pressure calculation unit is a first axis being the DC pressure extracted from the second cuff pressure or the converted DC pressure, and a second axis being the amplitude of the pressure pulse wave extracted from the first cuff pressure. A plurality of data points formed by the DC pressure extracted from the second cuff pressure or the converted DC pressure and the amplitude of the pressure pulse wave extracted from the first cuff pressure are plotted during the pressurization process or the depressurization process on a plane including the DC pressure extracted from the second cuff pressure or the converted DC pressure as a first axis, Connect adjacent data points with lines to create a mountain-shaped envelope curve. Calculate the diastolic and systolic blood pressure values ​​based on the mountain-shaped envelope. An electronic blood pressure monitor characterized by:

2. 2. The electronic blood pressure monitor according to claim 1, The DC pressure acquisition unit, during the pressurization process or the depressurization process, Extracting a DC pressure from the first cuff pressure and extracting the DC pressure from the second cuff pressure; determining an approximation equation for converting the DC pressure extracted from the first cuff pressure to the DC pressure extracted from the second cuff pressure based on a correspondence relationship between the DC pressure extracted from the first cuff pressure and the DC pressure extracted from the second cuff pressure; by converting the DC pressure extracted from the first cuff pressure into the DC pressure extracted from the second cuff pressure using the approximation formula, thereby obtaining the converted DC pressure; The first blood pressure calculation unit is Plotting a plurality of data points formed by the converted DC pressure derived from the first cuff pressure and the amplitude of the pressure pulse wave extracted from the first cuff pressure during the pressurization process or the depressurization process on the plane including the converted DC pressure derived from the first cuff pressure as a first axis and the amplitude of the pressure pulse wave extracted from the first cuff pressure as a second axis; Connect adjacent data points with lines to create a mountain-shaped envelope curve. Calculate the diastolic and systolic blood pressure values ​​based on the mountain-shaped envelope. An electronic blood pressure monitor characterized by:

3. 3. The electronic blood pressure monitor according to claim 2, The DC pressure acquisition unit obtains the approximation formula based on the inter-cuff pressure correspondence relationship over a predetermined first pressure section in the pressurization process or the depressurization process. An electronic blood pressure monitor characterized by:

4. 3. The electronic blood pressure monitor according to claim 2, a second blood pressure calculation unit that calculates a provisional blood pressure value prior to the operation of the DC pressure acquisition unit; The second blood pressure calculation unit is a first axis being the DC pressure extracted from the second cuff pressure, and a second axis being the amplitude of the pressure pulse wave extracted from the first cuff pressure or the second cuff pressure, on a plane including the DC pressure extracted from the second cuff pressure as a first axis and the amplitude of the pressure pulse wave extracted from the first cuff pressure or the second cuff pressure, plotting a plurality of data points formed by the DC pressure extracted from the second cuff pressure and the amplitude of the pressure pulse wave extracted from the first cuff pressure or the second cuff pressure during the pressurization process or the depressurization process; Connect adjacent data points with lines to create a mountain-shaped envelope curve. A provisional systolic blood pressure value is calculated based on the mountain-shaped envelope. As soon as the provisional systolic blood pressure value is obtained, the pressure control unit discharges the pressurizing fluid from the first cuff to reduce the pressure; The DC pressure acquisition unit is The approximation formula is obtained based on the correspondence relationship between the cuff pressures over a second pressure section from a predetermined lower limit pressure value to a maximum inflation value corresponding to the provisional systolic blood pressure value during the inflation process or the depressurization process. An electronic blood pressure monitor characterized by:

5. 3. The electronic blood pressure monitor according to claim 2, a storage unit that stores the past diastolic blood pressure values ​​and the past systolic blood pressure values ​​calculated by the first blood pressure calculation unit, The DC pressure acquisition unit obtains the approximation formula based on the correspondence relationship between the cuff pressures over a third pressure section corresponding to the past diastolic blood pressure values ​​and systolic blood pressure values ​​stored in the storage unit during the pressurization process or the depressurization process. An electronic blood pressure monitor characterized by:

6. 6. The electronic blood pressure monitor according to claim 1, a fluid containment control unit that controls the supply of the pressure transmission fluid to the second cuff and causes the fluid to be contained in the second cuff in a state in which the first and second cuffs are attached to surround the measurement site; An electronic blood pressure monitor comprising:

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