Sphygmomanometer

Abstract

A sphygmomanometer of the present application has a blood pressure measuring cuff (20) to be worn by winding around a measurement site, a pressure device (32, 33) to pressurize or depressurize the cuff (20), and a sound detecting device (35) to detect a sound emitted from the measurement site via the cuff (20). A magnification setting section (110) variably sets a magnification for a Korotkoff sound component based on a first passing time required for a pressure of the cuff (20) to pass through a first pressure range during pressurization of the cuff (20). A blood pressure calculating section (350, 110) receives an output of the sound detecting device (35) corresponding to the sound from the cuff (20), and amplifies a Korotkoff sound component contained in the output at the set magnification to calculate a blood pressure of the measurement site.

Description

TECHNICAL FIELD

[0001] The present application relates to a sphygmomanometer, and more particularly to a sphygmomanometer that compresses a measurement site and measures blood pressure based on Korotkoff sounds. BACKGROUND

[0002] In the past, as such a sphygmomanometer, for example, as disclosed in Patent Document 1 (Japanese Patent Application Laid-Open No. 53-136385), a technique is known in which, during a pressure reduction of a cuff (air bag), an amplification of an amplifier is made variable to make an amplitude of a Korotkoff sound detected per beat constant. Thereby, it is realized that a Korotkoff sound can be reliably recognized. Further, as disclosed in Patent Document 2 (Japanese Patent Application Laid-Open No. 5-317270), a technique is known in which, during a pressure reduction of a cuff, a K sound recognition level (a signal exceeding the K sound recognition level is processed as a Korotkoff sound) is variably set based on a pressure reduction speed. Thereby, it is realized that a Korotkoff sound can be stably recognized.

[0003] PRIOR ART DOCUMENTS

[0004] PATENT DOCUMENTS

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 53-136385

[0006] Patent Document 2: Japanese Patent Application Laid-Open No. 5-317270

[0007] Patent Document 3: Japanese Patent No. 5408125 SUMMARY

[0008] PROBLEMS TO BE SOLVED BY THE INVENTION

[0009] However, there is a tendency that, in a case where the measurement site is a thick arm (large in circumference), since there is more organism tissue between an artery and a body surface, a sound is difficult to transmit, and a Korotkoff sound level becomes small, on the other hand, in a case where the measurement site is a thin arm (small in circumference), since there is less organism tissue between an artery and a body surface, the Korotkoff sound level becomes large. Therefore, there is a problem that, if the amplification is set large based on the Korotkoff sound level in a case where the measurement site is a thick arm, a signal amplified with the amplification is saturated (i.e., exceeds an input range of a processor that processes the signal) in a case where the measurement site is a thin arm. As a result, the accuracy of blood pressure measurement is reduced. In the Patent Documents 1 and 2, such a problem is not recognized, and the technologies of the Patent Documents 1 and 2 do not solve the problem.

[0010] Therefore, an object of the present application is to provide a sphygmomanometer that can moderate or eliminate a size of a Korotkoff sound level depending on a circumference of a measurement site, and can measure blood pressure with high accuracy.

[0011] Technical means for solving the problem

[0012] To solve the problem, a sphygmomanometer of the present disclosure, which measures blood pressure by Korotkoff sounds emitted from a measurement site, is characterized by comprising:

[0013] having:

[0014] a sphygmomanometer cuff to be worn by being wrapped around a measurement site;

[0015] a pressure device to pressurize the sphygmomanometer cuff by supplying fluid thereto or to depressurize the sphygmomanometer cuff by discharging fluid therefrom;

[0016] a sound detection device to detect sounds emitted from the measurement site via the sphygmomanometer cuff;

[0017] a magnification setting section to measure a first passage time required for a pressure of the sphygmomanometer cuff to pass through a first pressure range set in advance during pressurization of the sphygmomanometer cuff by the pressure device, and variably set a magnification for a Korotkoff sound component in accordance with the first passage time; and

[0018] a blood pressure calculation section to receive an output of the sound detection device corresponding to sounds from the sphygmomanometer cuff during the pressurization or a depressurization process after the pressurization, amplify a Korotkoff sound component contained in the output at a magnification set by the magnification setting section, and calculate blood pressure of the measurement site based on the amplified Korotkoff sound component.

[0019] In the present specification, the "measurement site" includes an upper limb such as an upper arm, a wrist, and the like, or a lower limb such as a foot, and typically refers to a rod-shaped site.

[0020] The "sphygmomanometer cuff" typically includes a fluid bag for pressing the measurement site (referred to as a "pressing fluid bag").

[0021] The "pressure device" typically includes a pump, a valve, and the like.

[0022] The "sound detection device" typically includes a microphone.

[0023] The "first pressure range set in advance" refers to a range such as 25 mmHg to 35 mmHg.

[0024] In the sphygmomanometer of the present disclosure, the blood pressure measuring cuff is worn by being wound in the circumferential direction around the measurement site. In this worn state, during blood pressure measurement, air is supplied to the blood pressure measuring cuff (typically, a pressurizing fluid bag) by the pressure device. Thereby, the blood pressure measuring cuff is pressurized. Thereby, the measurement site is compressed, and the artery passing through the measurement site is occluded. During this pressurization, the amplification ratio setting section measures the first passage time required for the pressure (cuff pressure) of the blood pressure measuring cuff to pass through a first pressure range set in advance.

[0025] Here, if the first pressure range set in advance is 20 mmHg or more (for example, a range of 25 mmHg to 35 mmHg), as disclosed in Patent Document 3 (Japanese Patent No. 5408125), the first passage time required for the cuff pressure to pass through the first pressure range is independent of the winding strength of the cuff, and varies depending on the circumference of the measurement site (corresponding to the cuff size, particularly, the size of the pressurizing fluid bag).

[0026] Therefore, the amplification ratio setting section variably sets the amplification ratio of the Korotkoff sound component in accordance with the first passage time. The blood pressure calculating section receives the output of the sound detection device corresponding to the sound from the blood pressure measuring cuff during the pressurization or the depressurization after the pressurization, amplifies the Korotkoff sound component contained in the output at the amplification ratio set by the amplification ratio setting section, and calculates the blood pressure of the measurement site based on the amplified Korotkoff sound component. Thereby, the magnitude of the Korotkoff sound level depending on the circumference of the measurement site can be moderated or eliminated. That is, the situation that the amplified Korotkoff sound component exceeds the input range of the processor (forming the blood pressure calculating section) that processes this signal can be avoided. Therefore, according to this sphygmomanometer, the blood pressure can be measured with high accuracy.

[0027] In the sphygmomanometer of one embodiment, characterized in that,

[0028] The blood pressure measuring cuff includes:

[0029] an outer cloth extending in a length direction in a band shape for winding around the measurement site;

[0030] a pressurizing fluid bag provided on the side of the outer cloth facing the measurement site along the length direction for compressing the measurement site; and

[0031] a sound acquisition fluid bag provided between the outer cloth and the pressurizing fluid bag in a thickness direction perpendicular to the outer cloth for acquiring the sound from the measurement site via the pressurizing fluid bag,

[0032] The sphygmomanometer has:

[0033] a first fluid pipe connecting the pressing fluid bag and the pressure device in a fluid-communicable manner; and

[0034] a second fluid pipe, provided separately from the first fluid pipe, connecting the sound acquisition fluid bag and the sound detection device in a fluid-communicable manner.

[0035] The "side facing the measurement site" refers to a side facing the measurement site in a state in which the blood pressure measurement cuff is worn around the measurement site (referred to as a "wearing state").

[0036] With respect to the blood pressure measurement cuff, the "length direction" refers to a direction in which the outer cloth extends in a band shape, and corresponds to a circumferential direction around the measurement site in the wearing state. The "width direction" described later refers to a direction perpendicular to the length direction in a plane of the outer cloth, and corresponds to a direction in which an artery passes through the measurement site in the wearing state. In addition, the "thickness direction" refers to a direction perpendicular to the length direction and the width direction (i.e., the outer cloth), and corresponds to a direction perpendicular to an outer circumferential surface of the measurement site in the wearing state.

[0037] In the sphygmomanometer of the one embodiment, the blood pressure measurement cuff is worn around the measurement site in a manner in which the cuff is wound in the length direction of the cuff. In the wearing state, the pressing fluid bag, the sound acquisition fluid bag, and the outer cloth are arranged in this order in the thickness direction with respect to the measurement site. In the wearing state, air is supplied from the pressure device to the pressing fluid bag through the first fluid pipe at the time of blood pressure measurement. Thus, the pressing fluid bag is pressurized. During the pressurization, the pressing fluid bag and the sound acquisition fluid bag together expand in a direction away from the measurement site as a whole, and are restricted by the outer cloth. Thus, the pressing fluid bag expands in a direction pressing the measurement site. Thus, the measurement site is compressed, and an artery passing through the measurement site is blocked. Next, air is slowly discharged from the pressing fluid bag by the pressure device through the first fluid pipe. Thus, the pressing fluid bag is slowly depressurized.

[0038] In the present sphygmomanometer, the sound acquisition fluid bag acquires sound from the measurement site via the pressing fluid bag in the sphygmomanometer. In the wearing state, the pressing fluid bag extends along the circumference of the measurement site. Therefore, even if the wearing position of the sphygmomanometer with respect to the measurement site (particularly, the position in the circumference) is shifted, the influence on the level of sound from the artery passing through the measurement site into the pressing fluid bag is less, as a result of which the sound collection by the sound acquisition fluid bag is stabilized. Therefore, Korotkoff sound can be stably acquired. Furthermore, the second fluid pipe that fluidically connects the sound acquisition fluid bag and the sound detection device is provided separately from the first fluid pipe that fluidically connects the pressing fluid bag and the pressure device. Therefore, it is possible to prevent the mixing of a pulse sound (pulse wave sound) from a fluid system (referred to as a "first fluid system") including the pressing fluid bag, the first fluid pipe, and the pressure device into a fluid system (referred to as a "second fluid system") including the sound acquisition fluid bag, the second fluid pipe, and the sound detection device. Therefore, it is possible to further stably acquire Korotkoff sound.

[0039] In one embodiment of the sphygmomanometer, the sphygmomanometer is characterized in that

[0040] The length of the sphygmomanometer and / or the length of the length direction of the pressing fluid bag included in the sphygmomanometer is variably set according to the circumference of the measurement site.

[0041] The amplification rate setting section sets the amplification rate to be large according to the first transit time becoming longer as the length of the length direction and / or the width direction of the sphygmomanometer and / or the pressing fluid bag becomes longer.

[0042] There is a tendency that, in the case where the measurement site is a thick arm (large circumference), the level of Korotkoff sound becomes small because the organism tissue between the artery and the body surface is large, and, on the other hand, in the case where the measurement site is a thin arm (small circumference), the level of Korotkoff sound becomes large because the organism tissue between the artery and the body surface is small. Therefore, in the sphygmomanometer of the one embodiment, the amplification rate setting section sets the amplification rate to be large according to the first transit time becoming longer as the length of the length direction and / or the width direction of the sphygmomanometer and / or the pressing fluid bag becomes longer. Therefore, it is possible to reliably moderate or eliminate the size of the level of Korotkoff sound depending on the circumference of the measurement site. As a result, the blood pressure calculation section can further accurately measure blood pressure.

[0043] In one embodiment of the sphygmomanometer, the sphygmomanometer is characterized in that

[0044] The magnification setting section measures a second passing time required for the pressure of the blood pressure measurement cuff to pass through a second pressure range set in advance lower than the first pressure range during the pressurization of the blood pressure measurement cuff by the pressure device,

[0045] The magnification setting section sets the magnification to be large in accordance with the second passing time becoming longer as the winding strength of the blood pressure measurement cuff becomes looser.

[0046] The "second pressure range set in advance" refers to a range such as 10 mmHg to 15 mmHg.

[0047] There is a tendency that the Korotkoff sound level becomes smaller as the winding strength of the blood pressure measurement cuff becomes looser, and on the other hand, the Korotkoff sound level becomes larger as the winding strength of the blood pressure measurement cuff becomes tighter. Here, if it is a second pressure range set in advance lower than the first pressure range (for example, a range of 10 mmHg to 15 mmHg) as disclosed in, for example, Patent Literature 3 (Japanese Patent No. 5408125), the second passing time required for the cuff pressure to pass through the second pressure range varies depending on the cuff size and the winding strength. That is, the second passing time corresponds to the winding strength under the condition of a certain cuff size being set. Therefore, in the sphygmomanometer of this one embodiment, the magnification setting section measures the second passing time required for the pressure of the blood pressure measurement cuff to pass through the second pressure range during the pressurization of the blood pressure measurement cuff by the pressure device, and sets the magnification to be large in accordance with the second passing time becoming longer as the winding strength of the blood pressure measurement cuff becomes looser. Therefore, it is possible to reliably moderate or eliminate the size of the Korotkoff sound level depending on the winding strength of the blood pressure measurement cuff. As a result, the blood pressure calculation section can further measure blood pressure with high accuracy.

[0048] In another aspect, a sphygmomanometer of the present disclosure measures blood pressure by a Korotkoff sound emitted from a measurement site, characterized by

[0049] having:

[0050] a blood pressure measurement cuff worn around a measurement site;

[0051] a pressure device that pressurizes or depressurizes the blood pressure measurement cuff by supplying or discharging fluid to or from the blood pressure measurement cuff;

[0052] a sound detection device that detects a sound emitted from the measurement site via the blood pressure measurement cuff;

[0053] an input unit that inputs size information indicating which of a plurality of types of sizes of a cuff prepared in advance the cuff currently connected has;

[0054] a magnification setting unit that variably sets a magnification of a Korotkoff sound component in accordance with the size information input by the input unit; and

[0055] a blood pressure calculating unit that receives an output of the sound detecting device corresponding to a sound from the cuff during a pressurization process or a depressurization process based on the pressure device, amplifies a Korotkoff sound component included in the output at a magnification set by the magnification setting unit, and calculates a blood pressure of the measured site based on the amplified Korotkoff sound component.

[0056] In other words, the sphygmomanometer of the present disclosure has an input unit,

[0057] The input unit inputs size information indicating which of a plurality of types of sizes of a cuff prepared in advance the cuff currently connected has,

[0058] Instead of calculating the first transit time, the magnification setting unit variably sets a magnification of a Korotkoff sound component in accordance with the size information input by the input unit.

[0059] In the sphygmomanometer of the present disclosure, the input unit inputs size information indicating which of a plurality of types of sizes of a cuff prepared in advance the cuff currently connected has. Instead of calculating the first transit time, the magnification setting unit variably sets a magnification of a Korotkoff sound component in accordance with the size information input by the input unit. The blood pressure calculating unit receives an output of the sound detecting device corresponding to a sound from the cuff during a pressurization process or a depressurization process based on the pressure device, amplifies a Korotkoff sound component included in the output at a magnification set by the magnification setting unit, and calculates a blood pressure of the measured site based on the amplified Korotkoff sound component. As a result, a size of a Korotkoff sound level depending on a circumference of the measured site (corresponding to a size of a cuff) can be moderated or eliminated. Therefore, the blood pressure calculating unit can measure a blood pressure with high accuracy.

[0060] Effects of Invention

[0061] As described above, according to the sphygmomanometer of the present disclosure, a size of a Korotkoff sound level depending on a circumference of the measured site can be moderated or eliminated, and a blood pressure can be measured with high accuracy. BRIEF DESCRIPTION OF DRAWINGS

[0062] Figure 1 is a view showing an appearance of a sphygmomanometer of one embodiment of the present application.

[0063] Figure 2 is a diagram showing a frame structure of the sphygmomanometer.

[0064] Figure 3 (A) of FIG. 1 is a diagram schematically showing a planar layout of a sound acquisition fluid bag and a pressing fluid bag built in a cuff included in the sphygmomanometer in a state after the cuff is unwound. Figure 3 (B) of FIG. 1 is a diagram schematically showing cross sections of the sound acquisition fluid bag and the pressing fluid bag in a disassembled state.

[0065] Figure 4 (A) of FIG. 2 is a diagram schematically showing a manner in which the cuff is worn by being wound around an outer circumference of an upper arm as a measurement site. Figure 4 (B) of FIG. 2 is a diagram schematically showing a K sound signal (indicating Korotkoff sounds) acquired by the sound acquisition fluid bag using a sound detection device (microphone). Figure 4 (C) of FIG. 2 is a diagram schematically showing a pressure variation component acquired by the pressing fluid bag from a pressure sensor.

[0066] Figure 5 is a diagram showing an example of a blood pressure measurement procedure of the sphygmomanometer.

[0067] Figure 6 is a diagram showing Figure 5 a determination process of determining a cuff size and a winding strength of the cuff in the blood pressure measurement procedure of the sphygmomanometer.

[0068] Figure 7 is a diagram showing another example of a blood pressure measurement procedure of the sphygmomanometer.

[0069] Figure 8 is a diagram showing a relationship between a pressure (cuff pressure) of a pressing fluid bag included in the cuff and a pressurization time in a case where the cuff size and the winding strength of the cuff are changed.

[0070] Figure 9 is a diagram explaining a method of variably setting an amplification rate of a Korotkoff sound component depending on the cuff size and the winding strength of the cuff.

[0071] Figure 10 is a diagram showing changes in the cuff pressure and the K sound signal in blood pressure measurement in a case where the cuff size of the cuff is L (large) (appropriately referred to as an "L cuff") and the winding strength is just right (appropriately referred to as "just right winding").

[0072] Figure 11 is a diagram showing changes in the cuff pressure and the K sound signal in blood pressure measurement in a case where the cuff size of the cuff is M (medium) (appropriately referred to as an "M cuff") and the winding strength is just right winding.

[0073] Figure 12 is a graph showing changes in cuff pressure and K sound signal in blood pressure measurement when the cuff size of the cuff is S (small) (appropriately called "S cuff") and the winding strength is just wound.

[0074] Figure 13 is a graph showing changes in cuff pressure and K sound signal in blood pressure measurement when the cuff is M cuff and the winding strength is relaxed (appropriately called "relaxed winding").

[0075] Figure 14 is a graph showing changes in cuff pressure and K sound signal in blood pressure measurement when the cuff is M cuff and the winding strength is just wound.

[0076] Figure 15 is a graph showing changes in cuff pressure and K sound signal in blood pressure measurement when the cuff is M cuff and the winding strength is tight (appropriately called "tight winding"). DETAILED DESCRIPTION

[0077] Hereinafter, an embodiment of the present application will be described in detail with reference to the drawings.

[0078] (Outline structure of sphygmomanometer)

[0079] Figure 1 The appearance of a sphygmomanometer 100 of one embodiment of the present application is shown. The sphygmomanometer 100 has substantially: a cuff 20 for blood pressure measurement, which is worn by winding around a bar-shaped measured site 90 (refer to Figure 4 (A)) of an upper arm or a wrist, and a main body 10, which is fluidly connected to the cuff 20 via an air tube 38 as a first fluid pipe and an air tube 37 as a second fluid pipe.

[0080] (Structure of cuff for blood pressure measurement)

[0081] As is apparent from Figure 1 , the cuff 20 is configured by facing an outer cloth 21 of an elongated band shape (in this case, a rectangular shape with rounded corners) and an inner cloth 29 having a shape corresponding to the outer cloth 21, and sewing (or welding) peripheral portions 20s of these outer cloth 21 and inner cloth 29.

[0082] Figure 3 (A) of FIG. 8 schematically shows a planar layout of the sound acquisition fluid bag 22 and the pressing fluid bag 23, which are built in the cuff 20, in a state where the cuff 20 is spread. Figure 3(B) shows the cross sections of the sound acquisition fluid bag 22, the pressing fluid bag 23 in a disassembled state. Here, for the cuff 20, the length direction X refers to the direction in which the outer cloth 21 extends in a band shape, and corresponds to the circumferential direction of the measurement site 90 in the worn state (refer to (A) above). The width direction Y refers to the direction perpendicular to the length direction X in the plane of the outer cloth 21, and corresponds to the direction in which the artery 91 passes through the measurement site 90 in the worn state. Further, the thickness direction Z refers to the direction perpendicular to the two directions (i.e., the outer cloth 21) of the length direction X and the width direction Y, and corresponds to the direction perpendicular to the outer circumferential surface of the measurement site 90 in the worn state. Figure 4

[0083] As is clear from (B) above, in this example, the cuff 20 has the pressing fluid bag 23 and the sound acquisition fluid bag 22, which is formed separately from the pressing fluid bag 23, between the inner cloth 29 and the outer cloth 21. The pressing fluid bag 23 is provided on one side of the inner cloth 29 mainly for pressing the measurement site 90. The sound acquisition fluid bag 22 is provided between the outer cloth 21 and the pressing fluid bag 23 for acquiring the sound from the measurement site 90 via the pressing fluid bag 23. In this example, the sound acquisition fluid bag 22 is partially bonded to the pressing fluid bag 23 without positional deviation with respect to the pressing fluid bag 23. The pressing fluid bag 23 is partially bonded to the outer cloth 21 without positional deviation with respect to the outer cloth 21. Figure 3

[0084] As is clear from (A) above, the pressing fluid bag 23 has a substantially rectangular shape with a rounded corner extending in the length direction X in the plane of the outer cloth 21. The sound acquisition fluid bag 22 has a substantially rectangular shape with a smaller rounded corner than the pressing fluid bag 23 in the plane of the outer cloth 21. Figure 3

[0085] As is clear from (B) above, the pressing fluid bag 23 includes a pair of sheets 23a, 23b facing each other in the thickness direction Z, and the peripheral edge portions 23as, 23bs of the pair of sheets 23a, 23b are annularly joined (in this example, fused) to each other as indicated by the arrow M2 to be bag-shaped. The sound acquisition fluid bag 22 includes a pair of sheets 22a, 22b facing each other in the thickness direction Z, and the peripheral edge portions 22as, 22bs of the pair of sheets 22a, 22b are annularly joined to each other as indicated by the arrow Ml to be bag-shaped. In this example, the sheets 23a, 23b, 22a, 22b are made of a polyurethane resin. Figure 3 The pair of sheets 23a, 23b constituting the pressing fluid bag 23 has, at positions corresponding to each other, a plurality of through holes 23h in the thickness direction Z, as indicated by the arrow M3. The pair of sheets 22a, 22b constituting the sound acquisition fluid bag 22 has, at positions corresponding to each other, a plurality of through holes 22h in the thickness direction Z, as indicated by the arrow M4.

[0086] Figure 3 ​​​​(A) has roughly rectangular protrusions 23at and 23bt protruding in the width direction (-Y direction). With the air piping 38 sandwiched between the protrusions 23at and 23bt, the air piping 38 is connected to the pressing fluid bag 23 in a fluid-circulating manner by fully welding the portions 23tm and 23tm (indicated by oblique lines) of the protrusions 23at and 23bt corresponding to the sides of the air piping 38. The pressing fluid bag 23 can be expanded by being supplied with air through the air piping 38 and can be contracted by being exhausted from the air. Similarly, the pair of sheets 22a and 22b constituting the sound acquisition fluid bag 22 have, at corresponding positions, Figure 3 (A) has roughly rectangular protrusions 22at and 22bt protruding in the width direction (-Y direction). With the air tube 37 sandwiched between the protrusions 22at and 22bt, the air tube 37 is fully welded to the protrusions 22at and 22bt, corresponding to the two sides of the air tube 37 (indicated by diagonal lines). This connects the air tube 37 to the sound acquisition fluid bag 22 in a fluid-permeable manner. Sound acquired by the sound acquisition fluid bag 22 is transmitted to the main body 10 through the air tube 37 (details will be described later).

[0087] A plurality of protrusions 22p, 22p, ..., serving as spacers, are provided in the gaps between the pair of sheets 22a, 22b that form the sound acquisition fluid bag 22. In this example, these protrusions 22p, 22p, ... are short cylindrical in shape and integrally formed on the sheet 22b positioned on the side of the pressing fluid bag 23. This allows for a simple spacer configuration. In this example, these protrusions 22p, 22p, ... are dispersed at approximately equal intervals along the surface (XY plane) of the outer fabric 21. This prevents the pair of sheets 22a, 22b from coming into close contact during blood pressure measurement. Therefore, the sound acquisition fluid bag 22 can stably acquire sound from the measured area 90 via the pressing fluid bag 23. As a result, Korotkoff sounds can be stably acquired.

[0088] The outer fabric 21 is bendable or flexible, but is constructed to be substantially non-stretchable in order to prevent the sound acquisition fluid bag 22 and the pressing fluid bag 23 from expanding in a direction away from the measured area 90 as a whole during blood pressure measurement. Meanwhile, the inner fabric 29 is bendable or flexible and is constructed to be easily stretchable so that the pressing fluid bag 23 can easily compress the measured area 90 during blood pressure measurement. The outer fabric 21 and the inner fabric 29 are not limited to woven materials and may also be constructed from one or more layers of resin. The dimensions of the outer fabric 21 and the inner fabric 29 in the longitudinal direction X are set to be longer than the circumference of the measured area 90 (in this example, the upper arm). The dimensions of the outer fabric 21 and the inner fabric 29 in the width direction Y are set to be slightly larger than the dimensions of the pressing fluid bag 23 (and the sound acquisition fluid bag 22) in the width direction Y.

[0089] In the sphygmomanometer 100 provided with the cuff 20, the sound acquisition fluid bag 22 acquires the sound from the measurement site 90 via the pressing fluid bag 23. In the wearing state, the pressing fluid bag 23 extends along the circumference of the measurement site 90. Therefore, even if the wearing position (particularly, the position in the circumference) of the cuff 20 (the pressing fluid bag 23) with respect to the measurement site 90 is changed, the influence on the level of the sound from the artery 91 passing through the measurement site 90 into the pressing fluid bag 23 is less, and as a result, the sound collection based on the sound acquisition fluid bag 22 is stabilized. Therefore, the K sound signal Ks representing the Korotkoff sound can be stably acquired.

[0090] (Setting of the face direction dimensions of the pressing fluid bag, the sound acquisition fluid bag)

[0091] The face direction dimensions of the pressing fluid bag 23, the sound acquisition fluid bag 22 are set in accordance with the cuff size (set as the specification of the cuff, which determines the face direction dimensions of the outer cloth 21, the inner cloth 29). For example, as the cuff size, as shown in the "cuff size" column of Table 1 below, L (large), M (medium), and S (small) are set as for the upper arm.

[0092] (Table 1)

[0093]

[0094] Figure 3 The dimensions L1 in the length direction X, W1 in the width direction Y of the pressing fluid bag 23 shown in (A) are variably set in accordance with the cuff size corresponding to the arm circumference of the subject (the circumference of the measurement site 90), as shown in the "pressing fluid bag" column of Table 1. That is, when the cuff size for the upper arm is L (large), the dimensions in the length direction X and the width direction Y are set to L1 = 312.5 mm and W1 = 150.0 mm, respectively. When the cuff size for the upper arm is M (medium), the dimensions in the length direction X and the width direction Y are set to L1 = 235.0 mm and W1 = 125.0 mm, respectively. When the cuff size for the upper arm is S (small), the dimensions in the length direction X and the width direction Y are set to L1 = 167.0 mm and W1 = 90.0 mm, respectively. The cuff 20 is adapted to be worn on the subjects having various arm circumferences and wrist circumferences by the setting of the face direction dimensions L1, W1 of the pressing fluid bag 23. Similarly, the dimensions L2 in the length direction X, W2 in the width direction Y of the sound acquisition fluid bag 22 are variably set in accordance with the cuff size corresponding to the arm circumference of the subject, as shown in the "sound acquisition fluid bag" column of Table 1. Further, the cuff 20 having the cuff size L (large), M (medium), and S (small) is referred to as "L cuff", "M cuff", and "S cuff", respectively.

[0095] (Structure of the main body)

[0096] like Figure 2 As shown, the main body 10 is equipped with a control unit 110, a display 50, an operation unit 52, a memory 51 as a storage unit, a power supply unit 53, a pressure sensor 31, an oscillation circuit 310, a pump 32 and a control valve 33 as pressure devices, a pump drive circuit 320, a valve drive circuit 330, a microphone 35 as a sound detection device, a filter 349, an amplifier circuit 350, an atmosphere release valve 34, and a valve drive circuit 340. In this example, the air pipe 38a connected to the pressure sensor 31, the air pipe 38b connected to the pump 32, and the air pipe 38c connected to the control valve 33 merge to form a single air pipe 38 connected to the pressing fluid bag 23 in a fluid-flowable manner. The air pipe 38, which serves as the first fluid pipe, is a general term that includes these air pipes 38a, 38b, and 38c. Furthermore, air piping 37a connected to microphone 35 and air piping 37b connected to atmosphere release valve 34 merge to form a single air piping 37 connected to sound acquisition fluid bag 22 in a fluid-flowable manner. Air piping 37, which is the second fluid piping, is a general term that includes these air piping 37a and 37b.

[0097] like Figure 1 As shown in FIG, the display 50 and the operating unit 52 are arranged on the front panel 10f of the main body 10. In this example, the display 50 is composed of an LCD (Liquid Crystal Display) and displays predetermined information based on control signals from the control unit 110. In this example, systolic blood pressure SYS (unit: mmHg), diastolic blood pressure DIA (unit: mmHg), and pulse rate PULSE (unit: beats / minute) are displayed. Furthermore, the display 50 may be composed of an organic EL (Electro Luminescence) display or may include an LED (Light Emitting Diode).

[0098] In this example, the operation section 52 is constituted by a measurement switch (indicated by the same reference numeral 52 for simplicity) for receiving an instruction for starting (START) / stopping (STOP) measurement of blood pressure, and inputs an operation signal corresponding to the user's instruction to the control section 110. Specifically, when the measurement switch 52 is pressed, an operation signal to start measurement of blood pressure is input to the control section 110, and the control section 110 starts the blood pressure measurement described later (automatically stops when the blood pressure measurement is completed). When the measurement switch 52 is pressed during the blood pressure measurement, the control section 110 urgently stops the blood pressure measurement.

[0099] Figure 2 The memory 51 shown in FIG. 1 stores data of a program for controlling the sphygmomanometer 100, setting data for setting various functions of the sphygmomanometer 100, and data of a measurement result of a blood pressure value, and the like. In addition, the memory 51 is also used as a work memory or the like when the program is executed.

[0100] The control section 110 includes a CPU (Central Processing Unit) as a processor to control the overall operation of the sphygmomanometer 100. Specifically, the control section 110 functions as a pressure control section in accordance with a program for controlling the sphygmomanometer 100 stored in the memory 51, and controls the pump 32 and the control valve 33 as pressure devices in accordance with an operation signal from the operation section 52. In addition, the control section 110 functions as a blood pressure calculation section together with the amplification circuit 350, calculates a blood pressure value based on an output from the microphone 35, and controls the display 50 and the memory 51. The specific method of blood pressure measurement will be described later.

[0101] In this example, the pressure sensor 31 is a piezoresistive pressure sensor, and outputs a pressure (referred to as "cuff pressure Pc") of the pressurizing fluid bag 23 built in the cuff 20 through the air pipe 38 as a resistance caused by a piezoresistive effect. The oscillation circuit 310 oscillates at an oscillation frequency corresponding to the resistance from the pressure sensor 31. The control section 110 calculates the cuff pressure Pc from the oscillation frequency.

[0102] The pump 32 is driven by the pump drive circuit 320 based on a control signal supplied from the control section 110, and supplies air to the pressurizing fluid bag 23 built in the cuff 20 through the air pipe 38. Thus, the pressure (cuff pressure Pc) of the pressurizing fluid bag 23 is pressurized.

[0103] The control valve 33 is constituted by a normally open electromagnetic control valve, and is driven by the valve drive circuit 330 based on a control signal supplied from the control section 110, and is opened and closed in order to discharge or enclose air in the pressurizing fluid bag 23 through the air pipe 38 to control the cuff pressure.

[0104] The microphone 35 detects a sound acquired by the sound acquisition fluid bag 22 through the air pipe 37, and outputs an electric signal corresponding to the sound. In this example, the filter 349 performs filtering including Fast Fourier Transform (FFT) on the electric signal output from the microphone 35, and extracts a K sound signal (denoted by Ks) representing Korotkoff sounds. As illustrated in (B) of FIG. 3, typically, the K sound signal (Korotkoff sound component) Ks is obtained as a pulse-shaped signal that oscillates high and low with respect to a reference level ba. In (B) of FIG. 3, the amplitude of the peak-to-peak (Peak-to-peak) of the K sound signal Ks is denoted by Ap-p. The amplification circuit 350 amplifies the K sound signal Ks output from the filter 349 at an amplification rate a that is variably set. Based on the K sound signal after amplification (set as aKs), the control section 110 calculates the blood pressure of the measured site 90 (to be described later). Figure 4 Figure 4

[0105] Figure 2 The atmospheric opening valve 34 illustrated in FIG. 2 is configured of a normally open electromagnetic control valve, is driven by the valve drive circuit 340 based on a control signal supplied from the control section 110, and is opened and closed in order to open or close the second fluid system FS2 including the sound acquisition fluid bag 22 and the air pipe 37 to the atmosphere.

[0106] In this example, the first fluid system FS1 including the pressurizing fluid bag 23, the air pipe 38, the pressure sensor 31, the pump 32, and the control valve 33, and the second fluid system FS2 including the sound acquisition fluid bag 22, the air pipe 37, the microphone 35, and the atmospheric opening valve 34 are separated from each other in a fluid-communicable manner, and are also maintained separate within the main body 10. Thereby, it is possible to prevent a Korotkoff sound from being mixed into a sound (including a Korotkoff sound component) passing through the second fluid system FS2 (particularly, the air pipe 37) from the first fluid system FS1. Therefore, it is possible to stably acquire a Korotkoff sound.

[0107] The power supply section 53 supplies electric power to the control section 110, the display 50, the memory 51, the pressure sensor 31, the pump 32, the control valve 33, the microphone 35, the atmospheric opening valve 34, and other sections within the main body 10.

[0108] (Wearing method of blood pressure measurement cuff)

[0109] As illustrated in (A) of FIG. 1 (along the cross section passing through the artery 91 of the measured site 90), the cuff 20 is worn in a manner that the cuff 20 is wound around the outer circumferential surface of the measured site (in this example, the upper arm) 90 in the length direction X of the cuff 20. At the time of wearing, the outer cloth 21 is fixed not to come off by a not-illustrated surface fastener. Further, in (A) of FIG. 1, the pressurizing fluid bag 23 is illustrated as being pressed against the measured site 90. Figure 4 Figure 4 ​​​In (A), the inner cloth 29 is omitted for simplicity, and the pressurizing fluid bag 23 and the sound acquisition fluid bag 22 are each depicted in an elliptical shape. In this worn state, the inner cloth 29, the pressurizing fluid bag 23, the sound acquisition fluid bag 22, and the outer cloth 21 are arranged in this order in the thickness direction Z with respect to the outer surface of the measurement site 90. Further, in the worn state, the air tubes 37 and 38 extend toward the downstream side (-Y direction) of the blood flow through the artery 91, and thus the air tubes 37 and 38 do not interfere with the wearing.

[0110] (Blood pressure measurement)

[0111] Figure 5 An action flow when a user (in this case, a subject) performs a blood pressure measurement using the sphygmomanometer 100 is shown.

[0112] When the user instructs the start of measurement by the measurement switch 52 provided to the main body 10 in the worn state in which the cuff 20 is worn on the measurement site 90 (step S1), the control section 110 performs initialization (step S2). Specifically, the control section 110 initializes the memory area for processing, and performs 0 mmHg adjustment (sets atmospheric pressure to 0 mmHg) of the pressure sensor 31 in a state in which the pump 32 is stopped and the control valve 33 is opened. At this time, the atmospheric opening valve 34 is in an open state. Figure 5 Figure 5 Next, the control section 110 closes the atmospheric opening valve 34 and also closes the control valve 33 (step S3). The reason for closing the atmospheric opening valve 34 at this stage after the cuff 20 is worn on the measurement site 90 and before the start of pressurization of the pressurizing fluid bag 23 is to seal an appropriate amount of air in the sound acquisition fluid bag 22 in order to acquire Korotkoff sounds from the measurement site 90 via the pressurizing fluid bag 23. Further, closing the atmospheric opening valve 34 reduces background noise, and thus contributes to improvement in the signal-to-noise ratio (S / N ratio) when acquiring Korotkoff sounds.

[0113] Next, the control section 110 functions as a pressure control section, drives the pump 32, and starts pressurization of the cuff 20 (step S4). That is, the control section 110 supplies air from the pump 32 to the cuff 20 (the pressurizing fluid bag 23 built in the cuff 20) through the air tube 38. Along with this, the pressure sensor 31 functions as a pressure detection section, and detects the pressure of the pressurizing fluid bag 23 through the air tube 38. The control section 110 controls the pressurization speed of the pump 32 on the basis of the output of the pressure sensor 31.

[0114] At this time,

[0115] At this time, Figure 4 ​The expansion of the pressing fluid bag 23 shown in FIG. (A) and the sound acquisition fluid bag 22 in a direction away from the measurement site 90 is restricted as a whole by the outer fabric 21. Therefore, the pressing fluid bag 23 expands in a direction pressing the opposing region 90A of the measurement site 90. This compresses the region 90A of the measurement site 90 opposing the pressing fluid bag 23, and blood flow is blocked in the artery 91 passing through this region 90A.

[0116] During the pressurization process, the control unit 110 functions as an amplification factor setting unit, and first determines the cuff size and wrapping strength of the currently connected cuff 20 ( Figure 5 Here, the control unit 110 may display the determined cuff size and wrapping strength on the display 50, such as "M cuff, just wrapped". Then, the control unit 110 variably sets the cuff size and wrapping strength for the amplifier circuit 350 (see Figure 2 ) of the magnification α( Figure 5 The processing of these steps S5 and S6 will be described in detail later.

[0117] Next, in this example, the control unit 110 determines whether the pressure (cuff pressure Pc) of the cuff 20 (in this example, the pressing fluid bag 23) has reached a preset value Pu (for example, Figure 11 Here, the value Pu can be determined to be a blood pressure value that is sufficiently higher than the assumed blood pressure value of the subject, for example, 280 mmHg, or it can be determined to be the blood pressure value of the subject measured last time plus 40 mmHg. Figure 11 It can be seen that the pre-set value is Pu = 230 mmHg. The control unit 110 continues to pressurize until the cuff pressure Pc reaches the above value Pu = 230 mmHg. When the cuff pressure Pc reaches the above value Pu, the pump 32 is stopped (step S7). Figure 11 In the example of “M cuff, just wound” shown, at time t1 , the cuff pressure Pc reaches the value Pu, and the pump 32 stops.

[0118] Next, the control unit 110 slowly opens the control valve 33 ( Figure 5 Step S8). Thus, the cuff pressure Pc is decompressed at a substantially constant speed. In this example, during the decompression process, the sound acquisition fluid bag 22 acquires the sound from the measured part 90 via the pressing fluid bag 23. Furthermore, the microphone 35 detects the sound acquired by the sound acquisition fluid bag 22 through the air piping 37. The microphone 35 outputs an electrical signal corresponding to the sound. The filter 349 performs filtering including fast Fourier transform (FFT) on the electrical signal output by the microphone 35, and extracts the K sound signal Ks representing the Korotkoff sound. Figure 11In the example shown in FIG. 2 , the K-sound signal (Korotkoff sound component) Ks begins to be observed at time t2, gradually increases, reaches a maximum value, then gradually decreases, disappearing at time t3. Amplification circuit 350 amplifies the K-sound signal Ks output from filter 349 at the amplification factor α variably set in step S6. This amplified K-sound signal αKs is input to control unit 110.

[0119] The control unit 110 and the amplifier circuit 350 function as a blood pressure calculation unit, and try to calculate the blood pressure values ​​(systolic blood pressure SYS (Systolic Blood Pressure) and diastolic blood pressure DIA (Diastolic Blood Pressure)) based on the amplified K-sound signal αKs obtained at this time point. Figure 5 Step S9). Figure 11 In the example of FIG, the cuff pressure Pc detected by the pressure sensor 31 at time t2 is calculated as the systolic blood pressure SYS. In addition, the cuff pressure Pc detected by the pressure sensor 31 at time t3 is calculated as the diastolic blood pressure DIA.

[0120] Furthermore, a pulse wave signal (pressure fluctuation component) Pm ( ) as pulse wave information based on the pulse wave is superimposed on the cuff pressure Pc detected by the pressure sensor 31 from the compression fluid bag 23 through the air pipe 38. Figure 4 In this example, the control unit 110 calculates the pulse rate PULSE (beats / minute) based on the pulse wave signal Pm.

[0121] If the control unit 110 cannot calculate the blood pressure value and pulse rate due to insufficient data ( Figure 5 (If step S10 is "No"), the processing of steps S8 to S10 is repeated until calculation is possible.

[0122] Once the blood pressure and pulse rate are calculated ("YES" in step S10), the control unit 110 functions as a pressure control unit, opens the control valve 33, and rapidly discharges the air from the cuff 20 (compression fluid bag 23) (step S11). Furthermore, the air release valve 34 is opened.

[0123] Then, the control unit 110 displays the calculated blood pressure value and pulse rate on the display 50 (step S12 ), and performs control to store the blood pressure value and pulse rate in the memory 51 .

[0124] In this manner, in the blood pressure monitor 100 including the cuff 20 , the sound acquisition fluid bag 22 acquires the sound from the measurement site 90 via the pressing fluid bag 23 .

[0125] (Changes in K-sound signal due to cuff size and wrapping strength)

[0126] The present inventors focused on the fact that the amplitude Ap-p of the K sound signal Ks output from the filter 349 varies greatly depending on the cuff size and the winding strength of the cuff 20 currently connected. Further, as described above, the cuffs 20 having the cuff sizes of L (large), M (medium), and S (small) are respectively referred to as "L cuff", "M cuff", and "S cuff". In addition, the cases where the winding strength is loose, just right, and tight are respectively referred to as "loose winding", "just right winding", and "tight winding".

[0127] For example, in the case of "M cuff, just right winding" shown in FIG. 9, the amplitude of the K sound signal Ks output from the filter 349 becomes Ap-p = 1.2 V (Volt). Figure 11 In contrast, in the case of "M cuff, loose winding" shown in FIG. 10, the amplitude of the K sound signal Ks output from the filter 349 becomes Ap-p = 0.9 V. Figure 10 In contrast, in the case of "M cuff, loose winding" shown in FIG. 10, the amplitude of the K sound signal Ks output from the filter 349 becomes Ap-p = 0.9 V. Figure 12 In contrast, in the case of "M cuff, loose winding" shown in FIG. 10, the amplitude of the K sound signal Ks output from the filter 349 becomes Ap-p = 0.9 V.

[0128] Further, in the case of "M cuff, just right winding" shown in FIG. 9, the amplitude of the K sound signal Ks output from the filter 349 becomes Ap-p = 1.2 V, as in the case of FIG. 8. Figure 14 In contrast, in the case of "M cuff, loose winding" shown in FIG. 10, the amplitude of the K sound signal Ks output from the filter 349 becomes Ap-p = 0.9 V. Figure 11 In contrast, in the case of "M cuff, loose winding" shown in FIG. 10, the amplitude of the K sound signal Ks output from the filter 349 becomes Ap-p = 0.9 V. Figure 13 In contrast, in the case of "M cuff, loose winding" shown in FIG. 10, the amplitude of the K sound signal Ks output from the filter 349 becomes Ap-p = 0.9 V. Figure 15 In contrast, in the case of "M cuff, loose winding" shown in FIG. 10, the amplitude of the K sound signal Ks output from the filter 349 becomes Ap-p = 0.9 V.

[0129] Here, as in the case of FIG. 8, the amplitude of the K sound signal Ks output from the filter 349 becomes Ap-p = 1.2 V. Figures 10 to 15As shown in FIG, , the input range CPUin of the CPU included in the control unit 110 is 2.5 V (a fixed range) ranging from 0.5 V to 3.0 V. Therefore, the following problem arises: for example, if the amplification factor α is set to a large value based on the Korotkoff sound level (amplitude Ap-p of the K-sound signal Ks) in the case of "L cuff, loose winding", the K-sound signal αKs amplified by the amplification factor α in the case of "S cuff, tight winding" will be saturated (exceeding the input range CPUin).

[0130] Therefore, the present inventors have focused on the following invention: determining the cuff size and wrapping strength ( Figure 5 In step S5), the amplifier circuit 350 (refer to Figure 2 ) of the magnification α( Figure 5 Step S6).

[0131] (Determination of cuff size and winding strength)

[0132] Figure 8 The relationship between the pressure (cuff pressure Pc) of the compression fluid bag 23 contained in the cuff 20 and the pressurization time when the cuff size and wrapping strength of the cuff 20 are changed is shown. Figure 8 In the example shown in FIG1 , curves CLL, CLJ, and CLT are shown for "L cuff, loosely wrapped," "L cuff, properly wrapped," and "L cuff, tightly wrapped," respectively, indicating the increase in cuff pressure Pc with the passage of pressurization time. Furthermore, curves CML, CMJ, and CMT are shown for "M cuff, loosely wrapped," "M cuff, properly wrapped," and "M cuff, tightly wrapped," respectively, indicating the increase in cuff pressure Pc with the passage of pressurization time.

[0133] For example, as disclosed in Patent Document 3 (Japanese Patent No. 5408125), if the pressure is within the predetermined first pressure range ( Figure 8 The range of P3 to P4 shown in FIG is 25 to 35 mmHg in this example. This is referred to as the "first pressure range (P3, P4)"). The first passage time Δt1 required for the cuff pressure Pc to pass through the first pressure range (P3, P4) is independent of the wrapping strength of the cuff 20 and varies depending on the circumference of the measured part (corresponding to the cuff size, in particular, the size of the compression fluid bag 23). For example, in Figure 8In the example of FIG. 6, it is known that the first passage time Δtl 2 of the curve CLJ regarding the "L cuff, tight winding" is larger than the first passage time Δtl l of the curve CMJ regarding the "M cuff, just winding". Therefore, regarding the cuff 20 currently connected, the cuff size can be determined from the first passage time Δtl based on the above-described insight.

[0134] In addition, if it is a second pressure range (P1, P2) preset to be lower than the first pressure range (P3, P4) (for example, as disclosed in Patent Document 3 (Japanese Patent No. 5408125)), the second passage time Δt2 required for the cuff pressure Pc to pass through the second pressure range (P1, P2) shown in FIG. 5, which is a range of P1 to P2 in this example, a range of 10 mmHg to 15 mmHg in this example, varies depending on the cuff size and the winding strength. That is, under the condition set to a certain cuff size, the second passage time Δt2 corresponds to the winding strength of the cuff 20. For example, in the example of FIG. 6, it is known that the second passage time Δt23 of the curve CML regarding the "M cuff, loose winding" is larger than the second passage time Δt22 of the curve CMJ regarding the "M cuff, just winding", and further, the second passage time Δt21 of the curve CMT regarding the "M cuff, tight winding". This is the same for the L cuff. Therefore, regarding the cuff 20 currently connected, the winding strength can be determined from the cuff size and the second passage time Δt2 based on the above-described insight. Figure 8 In the example of FIG. 6, it is known that the first passage time Δtl 2 of the curve CLJ regarding the "L cuff, tight winding" is larger than the first passage time Δtl l of the curve CMJ regarding the "M cuff, just winding". Therefore, regarding the cuff 20 currently connected, the cuff size can be determined from the first passage time Δtl based on the above-described insight. Figure 8 In the example of FIG. 6, it is known that the first passage time Δtl 2 of the curve CLJ regarding the "L cuff, tight winding" is larger than the first passage time Δtl l of the curve CMJ regarding the "M cuff, just winding". Therefore, regarding the cuff 20 currently connected, the cuff size can be determined from the first passage time Δtl based on the above-described insight.

[0135] Figure 6 The specific flow of the step S5 of the determination of the winding strength based on the above-described insight is shown in FIG. 7. Figure 5 The specific flow of the step S5 of the determination of the winding strength based on the above-described insight is shown in FIG. 7. Figure 6 The specific flow of the step S5 of the determination of the winding strength based on the above-described insight is shown in FIG. 7.

[0136] Next, the control section 110 determines the cuff size of the cuff 20 currently connected based on the first passage time Δtl measured in the step S52 (step S53). Specifically, as along the curve CMJ shown in FIG. 6, the first passage time Δtl is compared with the first passage time Δtl l of the curve CMJ regarding the "M cuff, just winding", the first passage time Δtl 2 of the curve CLJ regarding the "L cuff, just winding", and the first passage time Δtl 3 of the curve CMJ regarding the "M cuff, tight winding". Then, the cuff size is determined based on the comparison result. Figure 9As shown on the horizontal axis (representing the first transit time Δt1), the range Δt1S from the lower limit to the upper limit of the first transit time Δt1 corresponding to the S cuff, the range Δt1M from the lower limit to the upper limit of the first transit time Δt1 corresponding to the M cuff, and the range Δt1L from the lower limit to the upper limit of the first transit time Δt1 corresponding to the L cuff are determined in advance based on actual measurements. The cuff size of the currently connected cuff 20 is then determined based on which of the ranges Δt1S, Δt1M, and Δt1L the measured first transit time Δt1 falls within.

[0137] Next, the control unit 110 performs the following operations according to Figure 6 The wrapping strength of the currently connected cuff 20 is determined based on the cuff size determined in step S53 and the second transit time Δt2 measured in step S51 (step S54). Specifically, for each cuff size, the range of the second transit time Δt2 corresponding to "loose wrapping," "perfect wrapping," and "tight wrapping" is determined in advance based on actual measurements. The wrapping strength of the currently connected cuff 20 is then determined based on the range within which the measured second transit time Δt2 falls for each cuff size.

[0138] (Magnification setting)

[0139] Figure 9 Shown in Figure 6 In step S6, the control unit 110 functions as an amplification factor setting unit, and variably sets the amplification factor α of the K-sound signal (Korotkoff sound component) Ks according to the cuff size and winding strength of the currently connected cuff 20. In this example, basically, the amplification factor α is variably set in a manner to alleviate or eliminate the size of the Korotkoff sound level (amplitude Ap-p of the K-sound signal Ks). Specifically, depending on whether the cuff size is an L cuff, an M cuff, or an S cuff, that is, depending on which range Δt1S, Δt1M, Δt1L the first passing time Δt1 falls into, the amplification factors αLJ, αMJ, and αSJ for "just winding" are determined like the function F1 that changes in a step-like manner. Then, for each cuff size, the amplification factors for "loose winding" and "tight winding" are determined to change. In Figure 9In the example of FIG. 6, the magnification for "loose winding" is determined to be aLL (> aLJ) and the magnification for "tight winding" is determined to be aLT (< aLJ) for the L cuff. The magnification for "loose winding" is determined to be aML (> aMJ) and the magnification for "tight winding" is determined to be aMT (< aMJ) for the M cuff. In addition, the magnification for "loose winding" is determined to be aSL (> aSJ) and the magnification for "tight winding" is determined to be aST (< aSJ) for the S cuff. The values of the magnification a thus variably set are, for example, the values shown in Table 2 below.

[0140] (Table 2)

[0141]

[0142] As described above, the amplification circuit 350 amplifies the K sound signal Ks at the magnification a thus variably set. Thereby, it is possible to moderate or eliminate the magnitude of the Korotkoff sound level (the amplitude Ap-p of the K sound signal Ks) depending on the cuff size and the winding strength. The amplified K sound signal aKs is input to the control section 110. Therefore, the amplified K sound signal aKs does not exceed the input range CPUin of the CPU included in the control section 110. Therefore, according to this sphygmomanometer 100, it is possible to measure the blood pressure with high precision.

[0143] (Modified Example 1)

[0144] In the above example, the control section 110 calculates the blood pressure value during the pressure reduction process, but is not limited thereto, and can calculate the blood pressure value during the pressure increase process of the cuff 20 (the pressurizing fluid bag 23 included in the cuff 20). For example, Figure 7 The blood pressure measurement flow in the case where the blood pressure value is calculated for the portion exceeding the first pressure range (P3, P4) during the above pressure increase process is shown.

[0145] In this Figure 7 In the blood pressure measurement flow of the sphygmomanometer 100, the control section 110 performs the same processing as in steps S1 to S6 of the sphygmomanometer 100 of Figure 5 In the blood pressure measurement flow of the sphygmomanometer 100, the control section 110 performs the same processing as in steps S1 to S6 of the sphygmomanometer 100 of Figure 7In step S107, the control unit 110 functions as a pressure control unit, continuing the pressurization control. During this pressurization process (i.e., the portion after exceeding the first pressure range (P3, P4)), the control unit 110 attempts to calculate the blood pressure value and pulse rate (step S108). Once the blood pressure value and pulse rate are calculated (step S109 returns "Yes"), the control unit 110 functions as a pressure control unit, stops the pump (step S110), opens the control valve 33, and controls the rapid discharge of air from the cuff 20 (pressing fluid bag 23) (step S111). Furthermore, the air release valve 34 is opened. The control unit 110 then displays the calculated blood pressure value and pulse rate on the display 50 (step S112) and controls the storage of the blood pressure value and pulse rate in the memory 51.

[0146] Even if the Figure 7 The blood pressure measurement process is also consistent with Figure 5 Similarly, the blood pressure measurement process can measure blood pressure with high accuracy.

[0147] (Variation 2)

[0148] As described Figures 10 to 12 As shown in FIG. 3 , when the cuff size changes from an L cuff to an S cuff, the amplitude Ap-p of the K-sound signal Ks output by the filter 349 changes from approximately 0.3 V to approximately 1.4 V (under the condition of “just wound”). Figures 13 to 15 As shown, when the winding strength changes from "loosely wound" to "tightly wound," the amplitude Ap-p of the K-sound signal Ks output by the filter 349 changes from approximately 0.9 V to approximately 1.5 V (under the "M cuff" condition). Thus, changes in cuff size have a greater impact on the amplitude Ap-p of the K-sound signal Ks than changes in winding strength. Therefore, rather than variably setting the amplification factor α of the K-sound signal Ks based on both the cuff size and the winding strength of the currently connected cuff 20, the amplification factor α can be variably set based only on the cuff size.

[0149] In this case, the control unit 110 functions as an amplification ratio setting unit, for example, Figure 9As shown in the function F1 that changes in a step-like manner, the amplification factor α can be variably set to αLJ, αMJ, or αSJ depending on whether the cuff size of the currently connected cuff 20 is an L cuff, an M cuff, or an S cuff, that is, depending on which range Δt1S, Δt1M, or Δt1L the first passing time Δt1 falls into. In this case, the amplitude Ap-p (Korotkoff sound level) of the K-sound signal Ks that depends on the cuff size can be alleviated or eliminated. As a result, the amplified K-sound signal αKs will not exceed the input range CPUin of the CPU included in the control unit 110. Therefore, blood pressure can be measured with high precision. At the same time, the determination process can be simplified ( Figure 6 ).

[0150] (Variation 3)

[0151] In the above example, the first transit time Δt1 is measured (step S52), and the cuff size is determined based on the first transit time Δt1 (step S53). However, this is not limiting. For example, the measurement switch 52 may be used as an input unit to input size information indicating which of multiple pre-prepared cuff sizes the currently connected cuff 20 has (e.g., L cuff, M cuff, or S cuff).

[0152] Size information can be input, for example, as follows. First, when the user presses and holds the measurement switch 52 for three seconds or longer, the control unit 110 enters a size information input mode. In this size information input mode, the control unit 110 inputs size information representing an L cuff, an M cuff, or an S cuff, depending on the number of times the measurement switch 52 is pressed.

[0153] When the size information is input, the control unit 110 functions as an amplification factor setting unit, and variably sets the amplification factor α for the K sound signal Ks based on the input size information, instead of determining the first transit time Δt1.

[0154] In this case, the amplitude Ap-p (Korotkoff sound level) of the K-sound signal Ks that depends on the cuff size can be mitigated or eliminated. Therefore, blood pressure can be measured with high accuracy. At the same time, the determination process can be simplified ( Figure 6 ).

[0155] (Variation 4)

[0156] In the above example, if Figure 9 As shown, the amplification factors αLJ, αMJ, and αSJ for "just-wrap" are determined, as shown by the step-like function F1, depending on which range Δt1S, Δt1M, and Δt1L the first transit time Δt1 falls into. However, this is not limiting. For example, the amplification factor α can also be variably set based on a curve that monotonically increases as the first transit time Δt1 increases.

[0157] In the above example, as the cuff size, L (large), M (medium), and S (small) for the upper arm are set, but the present application is not limited thereto. As for the upper arm, an XL (extra large) size larger than the L size can be set. In addition, a size for the wrist smaller than the S size for the upper arm can be set. In this case, in the sphygmomanometer 100, the amplification ratio a of the K sound signal Ks is variably set according to these cuff sizes.

[0158] In the above example, the microphone 35 as the sound detection device is mounted on the main body 10 and detects the sound from the sound acquisition fluid bag 22 through the air pipe 37, but the present application is not limited thereto. The microphone 35 as the sound detection device can be mounted on the cuff 20 in contact with the sound acquisition fluid bag 22 and directly detect the sound from the sound acquisition fluid bag 22.

[0159] The measurement site 90 is not limited to the upper arm, but can be an upper limb other than the upper arm such as the wrist or a lower limb such as the ankle.

[0160] The above embodiments are merely examples, and various modifications can be made without departing from the scope of the present application. The above embodiments can be established independently of each other, or the embodiments can be combined with each other. In addition, the features in the different embodiments can be established independently of each other, or the features in the different embodiments can be combined with each other.

[0161] Explanation of Reference Numerals

[0162] 10 main body

[0163] 20 cuff for blood pressure measurement

[0164] 22 sound acquisition fluid bag

[0165] 23 pressing fluid bag

[0166] 31 pressure sensor

[0167] 32 pump

[0168] 33 control valve

[0169] 34 atmospheric air opening valve

[0170] 35 microphone

[0171] 37, 38 air pipe

[0172] 100 sphygmomanometer

Claims

1. A sphygmomanometer that measures blood pressure from Korotkoff sounds emitted from a measurement site, characterized by comprising: a blood pressure measurement cuff that is worn by being wound around a measurement site; a pressure device that pressurizes the blood pressure measurement cuff by supplying fluid to the blood pressure measurement cuff or depressurizes the blood pressure measurement cuff by discharging fluid from the blood pressure measurement cuff; a sound detection device that detects sounds emitted from the measurement site via the blood pressure measurement cuff; a magnification setting section that measures a first passage time required for a pressure of the blood pressure measurement cuff to pass through a first pressure range set in advance during pressurization of the blood pressure measurement cuff by the pressure device, and variably sets a magnification of a Korotkoff sound component in accordance with the first passage time; and a blood pressure calculation section that receives an output of the sound detection device corresponding to the sounds from the blood pressure measurement cuff during pressurization or depressurization after the pressurization, amplifies a Korotkoff sound component contained in the output at the magnification set by the magnification setting section, and calculates blood pressure of the measurement site on the basis of the amplified Korotkoff sound component.

2. The sphygmomanometer according to claim 1, characterized in that the blood pressure measurement cuff includes: an outer cloth that extends in a length direction in a band shape to be wound around a measurement site; a pressing fluid bag that is provided on a side of the outer cloth opposite to the measurement site in the length direction to press the measurement site; and a sound acquisition fluid bag that is provided between the outer cloth and the pressing fluid bag in a thickness direction perpendicular to the outer cloth to acquire sounds from the measurement site via the pressing fluid bag, the sphygmomanometer includes: a first fluid pipe that connects the pressing fluid bag and the pressure device in a fluid flowable manner; and a second fluid pipe that is provided separately from the first fluid pipe, and connects the sound acquisition fluid bag and the sound detection device in a fluid flowable manner.

3. The sphygmomanometer according to claim 1 or 2, characterized in that a length of the length direction of the blood pressure measurement cuff and / or a pressing fluid bag included in the blood pressure measurement cuff is variably set in accordance with a circumference of the measurement site, the magnification setting section sets the magnification to be larger in accordance with the first passage time becoming longer as a length of the length direction and / or a width direction of the blood pressure measurement cuff and / or the pressing fluid bag becomes longer.

4. The sphygmomanometer according to any one of claims 1 or 2, characterized in that the magnification setting section measures a second passage time required for a pressure of the blood pressure measurement cuff to pass through a second pressure range set in advance that is lower than the first pressure range during pressurization of the blood pressure measurement cuff by the pressure device, the magnification setting section sets the magnification to be larger in accordance with the second passage time becoming longer as a winding strength of the blood pressure measurement cuff becomes looser.

5. A sphygmomanometer that measures blood pressure from Korotkoff sounds emitted from a measurement site, characterized by comprising: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ A cuff for blood pressure measurement is worn by being wound around a measurement site; A pressure device pressurizes the cuff for blood pressure measurement by supplying fluid thereto or depressurizes the cuff for blood pressure measurement by discharging fluid therefrom; A sound detection device detects a sound emitted from the measurement site via the cuff for blood pressure measurement; An input section inputs size information indicating which of a plurality of kinds of cuff sizes prepared in advance the cuff for blood pressure measurement currently connected has; A magnification setting section variably sets a magnification of a Korotkoff component in accordance with the size information input by the input section; and A blood pressure calculation section receives an output of the sound detection device corresponding to the sound from the cuff for blood pressure measurement during pressurization or depressurization by the pressure device, amplifies a Korotkoff component contained in the output at the magnification set by the magnification setting section, and calculates a blood pressure of the measurement site based on the amplified Korotkoff component. ​

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