Sphygmomanometer and blood pressure measuring method

Abstract

A sphygmomanometer (100) for measuring the blood pressure by pressing a measurement site of a user with a cuff (20), the sphygmomanometer (100) being provided with: a blood pressure measurement unit (220) for measuring the blood pressure of the user on the basis of a pulse wave signal during a pressure reduction process in which the cuff pressure indicating the internal pressure of the cuff (20) is increased to a pressure greater than a predetermined pressure after a pressurization process in which the cuff pressure is increased to a pressure greater than the predetermined pressure; reducing the pressure of the cuff; a determination unit (230) that determines whether or not an arrhythmia has occurred in the user on the basis of the pulse wave signal during the decompression process; and a mode setting unit (210) that sets either a first mode in which arrhythmia determination is performed or a second mode in which arrhythmia determination is not performed. The blood pressure measurement unit (220) slower a first pressure reduction rate of the cuff pressure when the first mode is set than a second pressure reduction rate of the cuff pressure when the second mode is set.

Description

Technical Field

[0001] The present disclosure relates to a sphygmomanometer and a blood pressure measuring method. Background Art

[0002] In the past, there is a known technology for detecting atrial fibrillation using a signal obtained during blood pressure measurement. For example, the blood pressure meter of Patent Document 1 (Japanese Patent Publication No. 2020-192322) determines atrial fibrillation by using the data of the interval time of the pulse signal of the measurement data in the pressurization phase and the data of the interval time of the pulse signal of the measurement data in the depressurization phase.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2020-192322 Summary of the invention

[0006] Problems to be solved by the invention

[0007] As a method for determining arrhythmia using a sphygmomanometer based on the oscillometric method, there is known a method for determining arrhythmia such as atrial fibrillation by using a pattern of pulse wave intervals obtained during the decompression of the cuff pressure. For example, the rising point or maximum point of the pulse wave signal of each beat is detected as a feature point, and the interval between the current beat and the previous beat is calculated as the pulse wave interval. In order to accurately calculate the pulse wave interval, the amplitude of the acquired pulse wave signal is preferably larger. Therefore, in order to improve the accuracy of arrhythmia determination based on the pattern of pulse wave intervals, it is necessary to increase the amplitude of the pulse wave signal to obtain a more accurate pulse wave interval.

[0008] An object of one aspect of the present disclosure is to provide a sphygmomanometer and a blood pressure measurement method that can accurately determine arrhythmia by acquiring a pulse wave signal with a large amplitude during a decompression process of blood pressure measurement.

[0009] Technical Solution

[0010] In one example of the present disclosure, a sphygmomanometer is provided for measuring blood pressure by compressing a measured part of a user with a cuff. The sphygmomanometer includes: a blood pressure measuring unit for measuring the blood pressure of the user based on a pulse wave signal during a decompression process, wherein the cuff pressure representing the internal pressure of the cuff is pressurized to a pressure greater than a prescribed pressure and then the cuff pressure is decompressed; a determination unit for determining whether the user has arrhythmia based on the pulse wave signal during the decompression process; and a mode setting unit for setting one of a first mode for performing arrhythmia determination and a second mode for not performing arrhythmia determination. The blood pressure measuring unit makes a first decompression speed of the cuff pressure when the first mode is set slower than a second decompression speed of the cuff pressure when the second mode is set.

[0011] According to the above configuration, arrhythmia can be determined with high accuracy by acquiring a pulse wave signal with a large amplitude during the decompression process of blood pressure measurement.

[0012] In another example of the present disclosure, the blood pressure measurement unit sets the first depressurization speed based on a pulse wave amplitude indicating an amplitude of a pulse wave signal during pressurization.

[0013] According to the above configuration, a more appropriate decompression speed can be set for the user.

[0014] In another example of the present disclosure, the sphygmomanometer further includes a storage unit that stores a pulse wave signal during a pressurization process or a decompression process when the blood pressure of the user is measured by the blood pressure measuring unit. The blood pressure measuring unit sets a first decompression speed based on a pulse wave amplitude representing an amplitude of a past pulse wave signal stored in the storage unit.

[0015] According to the above configuration, a more appropriate decompression speed can be set for the user.

[0016] In another example of the present disclosure, the blood pressure measurement unit sets the first decompression rate to be slower as the pulse wave amplitude is smaller.

[0017] According to the above configuration, arrhythmia determination can be performed with high accuracy at an appropriate measurement time.

[0018] In another example of the present disclosure, the blood pressure measurement unit sets the first depressurization rate to be slower as the time taken for the cuff pressure to reach a predetermined pressure during the pressurization process is longer.

[0019] According to the above configuration, arrhythmia determination can be performed with high accuracy at an appropriate measurement time.

[0020] In another example of the present disclosure, the blood pressure measurement unit estimates the size of the cuff based on the time it takes for the cuff pressure to reach a predetermined pressure during the pressurization process, and sets the first depressurization rate to be slower as the estimated cuff size is larger.

[0021] According to the above configuration, arrhythmia determination can be performed with high accuracy at an appropriate measurement time.

[0022] In another example of the present disclosure, the blood pressure meter further includes a wrapping strength detection unit that detects the wrapping strength of the cuff relative to the user's measured part based on the cuff pressure and the volume change of the cuff during the pressurization process. The blood pressure measurement unit sets the first decompression speed to be slower as the wrapping strength is smaller.

[0023] According to the above configuration, arrhythmia determination can be performed with high accuracy at an appropriate measurement time.

[0024] In another example of the present disclosure, the blood pressure measurement unit sets the second decompression speed based on an estimated pulse pressure that is a difference between an estimated systolic blood pressure and an estimated diastolic blood pressure and a predetermined pulse rate required to measure the user's blood pressure.

[0025] According to the above configuration, it is possible to quickly measure the blood pressure of a user who does not wish to have an arrhythmia determined.

[0026] In another example of the present disclosure, a blood pressure measurement method performed by a sphygmomanometer is provided, wherein the sphygmomanometer measures the blood pressure by compressing a measured part of a user with a cuff. The blood pressure measurement method includes the following steps: measuring the user's blood pressure based on a pulse wave signal during a decompression process, wherein the cuff pressure representing the internal pressure of the cuff is pressurized to a pressure greater than a specified pressure and then the cuff pressure is decompressed; determining whether the user has arrhythmia based on the pulse wave signal during the decompression process; and setting either a first mode for performing arrhythmia determination or a second mode for not performing arrhythmia determination. A first decompression speed of the cuff pressure when the first mode is set is slower than a second decompression speed of the cuff pressure when the second mode is set.

[0027] According to the above configuration, arrhythmia can be determined with high accuracy by acquiring a pulse wave signal with a large amplitude during the decompression process of blood pressure measurement.

[0028] Effects of the Invention

[0029] According to the present disclosure, arrhythmia can be determined with high accuracy by acquiring a pulse wave signal with a large amplitude during the decompression process of blood pressure measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a diagram showing a blood pressure monitor according to this embodiment.

[0031] Figure 2 This is a block diagram showing an example of the hardware configuration of the sphygmomanometer according to the first embodiment.

[0032] Figure 3This is a block diagram showing the functional configuration of the sphygmomanometer according to the first embodiment.

[0033] Figure 4 This is a graph showing the relationship between the pulse wave amplitude and the decompression rate during the pressurization process.

[0034] Figure 5 This is a graph showing the relationship between the pulse wave amplitude and the decompression rate obtained in the past.

[0035] Figure 6 This is a flowchart showing an example of the processing procedure of the sphygmomanometer according to the first embodiment.

[0036] Figure 7 This is a flowchart showing another example of the processing procedure of the sphygmomanometer according to the first embodiment.

[0037] Figure 8 This is a flowchart showing another example of the processing procedure of the sphygmomanometer according to the first embodiment.

[0038] Fig. 9 This is a diagram for explaining the relationship between the time required to reach a predetermined pressure and the decompression rate.

[0039] Fig.10 This is a diagram for explaining the relationship between the time required to reach a predetermined pressure, the decompression rate, and the cuff size.

[0040] Fig.11 This is a flowchart showing an example of the processing procedure of the sphygmomanometer according to the second embodiment.

[0041] Fig.12 This is a flowchart showing another example of the processing procedure of the sphygmomanometer according to the second embodiment.

[0042] Fig.13 This is a block diagram showing the functional configuration of a sphygmomanometer according to the third embodiment.

[0043] Fig.14 This is a flowchart showing an example of a processing procedure of the sphygmomanometer according to the third embodiment. DETAILED DESCRIPTION

[0044] Hereinafter, the embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, the same components are marked with the same reference numerals. Their names and functions are also the same. Therefore, they will not be described in detail again.

[0045] [Application examples]

[0046] Reference Figure 1 , an application example of the present invention is described. Figure 1 It is a diagram showing a sphygmomanometer 100 according to this embodiment.

[0047] Reference Figure 1 The sphygmomanometer 100 is an upper arm sphygmomanometer that measures blood pressure by compressing the measured part of the user (i.e., the subject) with a cuff. The sphygmomanometer 100 performs blood pressure measurement based on the oscillometric method. The sphygmomanometer 100 has a main body and a cuff (armband) as main components. It should be noted that the sphygmomanometer 100 can also be a wrist sphygmomanometer in which the main body and the cuff (armband) are integrated. Figure 1 Describe the processing content.

[0048] exist Figure 1 In the embodiment, a scenario is assumed in which a user measures his / her own blood pressure using the sphygmomanometer 100. The sphygmomanometer 100 measures the user's blood pressure by a decompression measurement method of measuring the blood pressure during the decompression of the cuff pressure, wherein the cuff pressure represents the internal pressure of the cuff attached to the user's measured part (e.g., arm).

[0049] The sphygmomanometer 100 starts to pressurize the cuff (corresponding to Figure 1 of (1)).

[0050] The sphygmomanometer 100 estimates the systolic blood pressure (maximum blood pressure) and the diastolic blood pressure (minimum blood pressure) (corresponding to Figure 1 (2)). The systolic blood pressure and the diastolic blood pressure are estimated by a known method. For example, the sphygmomanometer 100 estimates the systolic blood pressure and the diastolic blood pressure based on the pulse wave envelope curve representing the pattern of the amplitude change of the pulse wave signal that changes during the process of increasing the cuff pressure. Hereinafter, the estimated systolic blood pressure will be referred to as the "estimated systolic blood pressure", and the estimated diastolic blood pressure will be referred to as the "estimated diastolic blood pressure".

[0051] The sphygmomanometer 100 selects either a normal measurement mode (hereinafter, also referred to as “normal mode”) or an arrhythmia determination mode (corresponding to Figure 1 (3)). The arrhythmia determination mode is a mode in which arrhythmia determination is performed together with blood pressure measurement based on the pulse wave signal during the decompression process of the cuff pressure immediately after the pressurization process. The general mode is a mode in which only blood pressure measurement is performed based on the pulse wave signal during the decompression process without performing arrhythmia determination. Here, it is assumed that the arrhythmia determination mode is selected.

[0052] The sphygmomanometer 100 sets the decompression speed of the cuff pressure during the decompression process in the arrhythmia determination mode (corresponding to Figure 1(4)). Here, in the general mode, the decompression speed is set in such a way that a predetermined number of pulses is obtained between the estimated pulse pressure, which is the difference between the estimated systolic blood pressure and the estimated diastolic blood pressure. The decompression speed in the arrhythmia determination mode is set slower than the decompression speed in the general mode. It is known that if the decompression speed is slowed down, the amplitude of the pulse wave signal obtained during the decompression process (hereinafter referred to as "pulse wave amplitude") will increase. Therefore, the pulse wave amplitude obtained during the decompression process in the arrhythmia determination mode is larger than the pulse wave amplitude obtained during the decompression process in the general mode.

[0053] The sphygmomanometer 100 calculates the user's blood pressure value based on the pulse wave signal obtained during the decompression process, and determines whether arrhythmia occurs (corresponding to Figure 1 (5)). In this case, the sphygmomanometer 100 displays the user's blood pressure value and the result of the arrhythmia determination on the display.

[0054] According to the above application example, the pulse wave amplitude obtained in the arrhythmia determination mode is larger than the pulse wave amplitude obtained in the general mode, so a more accurate pulse wave interval pattern can be obtained in the arrhythmia determination mode. Therefore, the blood pressure meter 100 can perform more accurate arrhythmia determination.

[0055] It should be noted that the sphygmomanometer 100 creates a pulse wave envelope based on the amplitude of the acquired pulse wave signal and the cuff pressure, and calculates the blood pressure based on the pulse wave envelope. The sphygmomanometer 100 performs processing such as modification and smoothing of the pulse wave envelope so that the blood pressure can be calculated even when the acquired pulse wave signal is small and cannot be identified as a pulse wave. Therefore, in the general mode with a fast decompression speed, the sphygmomanometer 100 can calculate the blood pressure in a short measurement time. Therefore, the blood pressure measurement can be performed quickly for users who do not want to perform arrhythmia determination.

[0056] As described above, according to the sphygmomanometer 100 of the present embodiment, arrhythmia can be determined with high accuracy by acquiring a pulse wave signal with a large amplitude during the decompression process of blood pressure measurement.

[0057] [Configuration example]

[0058] <Implementation Method 1>

[0059] (Hardware composition)

[0060] Figure 2 1 is a block diagram showing an example of the hardware configuration of the sphygmomanometer 100 according to the first embodiment. Figure 2The sphygmomanometer 100 includes a main body 10 and a cuff 20 as main components. A fluid bag 22 is contained in the cuff 20. The main body 10 includes a processor 110, an air system component 30 for blood pressure measurement, an A / D conversion circuit 310, a pump drive circuit 320, a valve drive circuit 330, a display 50, a memory 51, an operation unit 52, a communication interface 53, and a power supply unit 54.

[0061] The processor 110 is a calculation processing unit such as a CPU (Central Processing Unit) or an MPU (MultiProcessing Unit). The processor 110 implements various processes (steps) of the sphygmomanometer 100 described later by reading and executing a program stored in the memory 51. For example, the processor 110 controls the driving pump 32 and the valve 33 according to an operation signal from the operation unit 52. In addition, the processor 110 calculates the blood pressure value using an algorithm for calculating the blood pressure based on the oscillometric method, and displays the blood pressure value on the display 50.

[0062] The memory 51 is implemented by a RAM (Random Access Memory), a ROM (Read-Only Memory), a flash memory, etc. The memory 51 stores: a program for controlling the sphygmomanometer 100, data for controlling the sphygmomanometer 100, setting data for setting various functions of the sphygmomanometer 100, and data of measurement results of blood pressure values, pulse counts, pulse wave intervals, etc. In addition, the memory 51 is used as a working memory when executing a program, etc.

[0063] The air system assembly 30 supplies air to the fluid bag 22 contained in the cuff 20 or discharges air from the fluid bag 22 contained in the cuff 20 through the gas piping. The air system assembly 30 includes: a pressure sensor 31 for detecting the pressure in the fluid bag 22; and a pump 32 and a valve 33 as an expansion and contraction mechanism for expanding and contracting the fluid bag 22.

[0064] The pressure sensor 31 detects the pressure (cuff pressure) in the fluid bag 22, and outputs a signal (cuff pressure signal) corresponding to the detected pressure to the A / D conversion circuit 310. The pressure sensor 31 is, for example, a piezoresistive pressure sensor, and is connected to the pump 32, the valve 33, and the fluid bag 22 contained in the cuff 20 via a gas pipe. In order to pressurize the cuff pressure, the pump 32 supplies air as a fluid to the fluid bag 22 via the gas pipe. The valve 33 opens / closes in order to discharge the air in the fluid bag 22 or to seal the air into the fluid bag 22 via the gas pipe to control the cuff pressure.

[0065] The A / D conversion circuit 310 converts the output value of the pressure sensor 31 (e.g., a voltage value corresponding to a change in resistance caused by the piezoresistive effect) from an analog signal into a digital signal and outputs it to the processor 110. The processor 110 obtains a signal indicating the cuff pressure based on the output value of the A / D conversion circuit 310. The pump drive circuit 320 controls the drive of the pump 32 based on a control signal given by the processor 110. The valve drive circuit 330 controls the opening / closing of the valve 33 based on a control signal given by the processor 110.

[0066] When measuring blood pressure according to the oscillometric method, the following actions are generally performed. Specifically, the cuff is pre-wound around the measured part (wrist, arm, etc.) of the subject. During the measurement, the pump 32 and the valve 33 are controlled to increase the cuff pressure to a level higher than the estimated systolic blood pressure, and then the cuff pressure is gradually reduced. During the decompression process, the cuff pressure is detected by a pressure sensor, and the change in arterial volume generated in the artery of the measured part is taken out as a pulse wave signal. Based on the change in the amplitude of the pulse wave signal (mainly rising and falling) accompanied by the change in the cuff pressure at this time, the systolic blood pressure and the diastolic blood pressure are calculated.

[0067] The operation unit 52 inputs an operation signal corresponding to the user's instruction to the processor. The operation unit 52 includes a measurement switch 52A for accepting a blood pressure measurement instruction from the user and a mode selection switch 52B for selecting a measurement mode.

[0068] When the measurement switch 52A is pressed, the measurement site is temporarily compressed by the cuff 20, and the blood pressure measurement is performed by the oscillometric method. When the measurement switch 52A is pressed again during the blood pressure measurement, the blood pressure measurement is stopped.

[0069] When the mode selection switch 52B is pressed, the measurement mode is switched. For example, when the current measurement mode is set to the normal mode, when the mode selection switch 52B is pressed, the measurement mode is switched to the arrhythmia determination mode.

[0070] The display 50 displays various information including blood pressure measurement results based on a control signal from the processor 110. The communication interface 53 exchanges various information with an external device. The power supply unit 54 supplies power to the processor 110 and various hardware.

[0071] (Functional composition)

[0072] Figure 3 2 is a block diagram showing the functional configuration of the sphygmomanometer 100 according to the first embodiment. Figure 3The sphygmomanometer 100 includes a mode setting unit 210, a blood pressure measuring unit 220, a determination unit 230, and an output control unit 240 as main functional components. These functions are implemented, for example, by causing the processor 110 of the sphygmomanometer 100 to execute a program stored in the memory 51. It should be noted that some or all of these functions may also be implemented by hardware. The sphygmomanometer 100 also includes a storage unit 250. The storage unit 250 is implemented by the memory 51.

[0073] The mode setting unit 210 sets one of an arrhythmia determination mode in which the user determines whether or not there is an arrhythmia and a general mode in which the arrhythmia determination is not performed. Typically, the mode setting unit 210 sets one of the arrhythmia determination mode and the general mode in accordance with a mode selection instruction given by the user via the operation unit 52 (e.g., the mode selection switch 52B).

[0074] It should be noted that the mode setting unit 210 may be configured to automatically set one of the modes according to a predetermined schedule. For example, when blood pressure measurement is started in time period H of a day (for example, blood pressure measurement is started by pressing the measurement switch 52A), the arrhythmia determination mode is automatically set. On the other hand, when blood pressure measurement is performed in a time period other than time period H of a day, the general mode is automatically set.

[0075] The blood pressure measuring unit 220 controls the cuff pressure in accordance with a measurement start instruction given by the user via the operation unit 52 (e.g., the measurement switch 52A). Specifically, the blood pressure measuring unit 220 controls the pump 32 to be driven via the pump driving circuit 320 and the valve 33 to be driven via the valve driving circuit 330. The valve 33 is opened / closed in order to discharge or seal air in the fluid bag 22 and control the cuff pressure.

[0076] The blood pressure measuring unit 220 receives the cuff pressure signal detected by the pressure sensor 31, and extracts a pulse wave signal representing the pulse wave of the measured part superimposed on the cuff pressure signal. That is, the blood pressure measuring unit 220 detects the pressure component, i.e., the pulse wave, superimposed on the cuff pressure signal in synchronization with the heart beat of the user from the cuff pressure signal.

[0077] The blood pressure measuring unit 220 calculates the user's blood pressure information based on the cuff pressure signal and the pulse wave signal superimposed on the cuff pressure signal. Specifically, the blood pressure measuring unit 220 measures the user's blood pressure according to the oscillometric method. In the present embodiment, a decompression measurement method is adopted to measure the user's blood pressure based on the pulse wave signal during the decompression process, wherein the decompression process decompresses the cuff pressure after a pressurization process in which the cuff pressure is pressurized to a pressure greater than a specified pressure (e.g., an estimated systolic blood pressure). Typically, the blood pressure measuring unit 220 calculates the systolic blood pressure, diastolic blood pressure, pulse rate, and pulse pressure. The storage unit 250 stores information obtained during the blood pressure measurement (e.g., pulse wave signal, systolic blood pressure, diastolic blood pressure, pulse rate, pulse pressure, etc.).

[0078] The blood pressure measurement unit 220 sets the cuff pressure decompression speed during decompression based on the measurement mode set by the mode setting unit 210. Specifically, the blood pressure measurement unit 220 sets the cuff pressure decompression speed G1 when the arrhythmia determination mode is set slower than the cuff pressure decompression speed G2 when the normal mode is set.

[0079] Typically, the blood pressure measuring unit 220 obtains an estimated systolic blood pressure and an estimated diastolic blood pressure based on the pulse wave signal during the pressurization process, and sets the decompression speed G2 based on the estimated pulse pressure, which is the difference between the estimated systolic blood pressure and the estimated diastolic blood pressure, and a predetermined pulse rate (e.g., eight) required for measuring the user's blood pressure. For example, the sphygmomanometer 100 sets the decompression speed G2 so that the pulse rate generated between the estimated pulse pressures becomes equal to or higher than the predetermined pulse rate.

[0080] There are several methods for setting the decompression speed G1 by the blood pressure measuring unit 220. In one aspect, the blood pressure measuring unit 220 sets the decompression speed G1 to a predetermined speed (e.g., 4 mmHg / s). This speed (e.g., 4 mmHg / s) is sufficiently slower than the decompression speed G2 calculated in the above manner.

[0081] On the other hand, the blood pressure measurement unit 220 sets the decompression speed G1 based on the pulse wave amplitude during the pressurization process. The smaller the pulse wave amplitude is, the slower the blood pressure measurement unit 220 sets the decompression speed G1.

[0082] Figure 4 This is a graph showing the relationship between the pulse wave amplitude and the decompression rate during the pressurization process. Figure 4 The vertical axis of the curve graph represents the decompression speed G1, and the horizontal axis represents the maximum pulse wave amplitude obtained during the pressurization process. It can be seen that the smaller the maximum pulse wave amplitude during the pressurization process, the slower the decompression speed G1. This is to perform high-precision arrhythmia determination by obtaining a pulse wave amplitude of a certain size or more during the decompression process.

[0083] Specifically, there is the following positive correlation: when the pulse wave amplitude during the pressurization process is large, the pulse wave amplitude during the decompression process is also large. Therefore, when the pulse wave amplitude during the pressurization process is small, the decompression speed is slowed down so that the pulse wave amplitude obtained during the decompression process becomes larger. On the other hand, when the pulse wave amplitude during the pressurization process is large enough, it is believed that a large pulse wave amplitude will also be obtained during the decompression process, so the decompression speed is increased. In this case, the measurement time becomes shorter. In this way, the decompression speed G1 is set to the decompression speed required to obtain a pulse wave amplitude of a certain size or more. As a result, a more appropriate decompression speed can be set for the user, and high-precision arrhythmia determination can be achieved with an appropriate measurement time.

[0084] Refer again Figure 3 The blood pressure measurement unit 220 sets the decompression speed G1 based on the amplitude of the past pulse wave signal (ie, the pulse wave amplitude) stored in the storage unit 250 .

[0085] Figure 5 This is a graph showing the relationship between the pulse wave amplitude and the decompression rate obtained in the past. Figure 5 The vertical axis of the graph represents the decompression speed G1, and the horizontal axis represents the pulse wave amplitude obtained during the pressurization process or the decompression process when the user's blood pressure was measured in the past (hereinafter, also referred to as "pulse wave amplitude Am" for convenience). It can be seen that the smaller the pulse wave amplitude Am, the slower the decompression speed G1. This is to perform high-precision arrhythmia determination by obtaining a pulse wave amplitude of a certain size or more during the decompression process.

[0086] Specifically, if the pulse wave amplitude Am obtained in the past is small, it is estimated that the pulse wave amplitude during the decompression process during the current blood pressure measurement is also small. Therefore, if the pulse wave amplitude Am obtained in the past is small, the decompression speed is slowed down so that the pulse wave amplitude obtained in the current decompression process becomes larger. On the other hand, if the pulse wave amplitude Am obtained in the past is large enough, it is estimated that a large pulse wave amplitude will also be obtained in the current decompression process, so the decompression speed is increased. In this case, the measurement time becomes shorter. In this way, Figure 4 Similarly, the decompression speed G1 is set to the decompression speed required to obtain a pulse wave amplitude of a certain size or more. In this case, a more appropriate decompression speed can be set for the user, and a high-precision arrhythmia determination can be achieved with an appropriate measurement time.

[0087] The storage unit 250 stores pulse wave amplitudes during a specified period in the past. For example, the storage unit 250 stores pulse wave signals during the pressurization process or the decompression process when measuring the user's blood pressure. As an example, the blood pressure measurement unit 220 calculates the average value of the maximum pulse wave amplitude during the pressurization process during the most recent multiple (for example, three) blood pressure measurements based on the data stored in the storage unit 250, and sets the average value as the pulse wave amplitude Am. As another example, the blood pressure measurement unit 220 extracts data from past blood pressure measurements in the same time period (for example, early morning, daytime, night, etc.) as the current blood pressure measurement, and sets the maximum pulse wave amplitude during the pressurization process during the blood pressure measurement as the pulse wave amplitude Am. As yet another example, the blood pressure measurement unit 220 sets the maximum pulse wave amplitude during the pressurization process of multiple blood pressure measurements in a specified period (for example, one day) as the pulse wave amplitude Am.

[0088] Refer again Figure 3 When the arrhythmia determination mode is set, the determination unit 230 determines whether the user has arrhythmia based on the pulse wave signal during the decompression process. A known method is used for determining arrhythmia. For example, the determination unit 230 determines whether arrhythmia occurs based on the generation interval of multiple pulse waves (i.e., pulse wave interval) obtained from the pulse wave signal.

[0089] The output control unit 240 displays the measurement results of the blood pressure measurement unit 220 and the determination results of the determination unit 230 on the display 50. It should be noted that the output control unit 240 can send the measurement results and the determination results to an external device via the communication interface 53, or can be configured to output sound via a speaker (not shown).

[0090] (Processing process)

[0091] Figure 6 1 is a flowchart showing an example of the processing procedure of the sphygmomanometer 100 according to Embodiment 1. At the start time of the processing, it is assumed that the user is wearing the cuff 20 of the sphygmomanometer 100. Figure 6 In the example, it is assumed that the normal mode or the arrhythmia determination mode is set as the measurement mode.

[0092] Reference Figure 6 , the processor 110 of the sphygmomanometer 100 receives a start instruction of blood pressure measurement from the user via the measurement switch 52A of the operation unit 52 (step S10). The processor 110 initializes the pressure sensor 31 (step S12). Specifically, the processor 110 initializes the processing storage area, and performs 0 mmHg adjustment (setting the atmospheric pressure to 0 mmHg) of the pressure sensor 31 in a state where the pump 32 is disconnected (stopped) and the valve 33 is opened.

[0093] The processor 110 closes the valve 33 via the valve drive circuit 330 (step S14), turns on (starts) the pump 32 via the pump drive circuit 320, and starts pressurizing the cuff 20 (fluid bag 22) (step S16). Typically, the processor 110 controls the pump drive circuit 320 to drive the pump 32 so that the pressure increase speed of the cuff pressure is constant.

[0094] The processor 110 extracts the pulse wave signal from the cuff pressure signal detected by the pressure sensor 31, and calculates the estimated systolic blood pressure, the estimated diastolic blood pressure, and the pulse rate based on the pulse wave signal obtained during the pressurization process (step S18). The processor 110 determines whether the cuff pressure reaches or exceeds the threshold value Th (step S20). Typically, the threshold value Th is set to a value that is a fixed value (e.g., 40 mmHg) higher than the estimated systolic blood pressure.

[0095] When the cuff pressure is less than the threshold value Th (NO in step S20), the processor 110 returns to step S16. When the cuff pressure is greater than the threshold value Th (YES in step S20), the processor 110 stops the pump 32 (step S22) and determines whether the currently set measurement mode is the normal mode (step S24).

[0096] First, the case where the measurement mode is the general mode (Yes in step S24) is described. The processor 110 calculates the decompression speed G2 based on the estimated pulse pressure and the pulse rate, which are the difference between the estimated systolic blood pressure and the estimated diastolic blood pressure (step S26). The processor 110 controls the valve 33 to gradually open according to the decompression speed G2 (step S28). As a result, the process of pressurization is changed to the process of decompression, and the cuff pressure is gradually reduced according to the decompression speed G2.

[0097] During the decompression process, the processor 110 extracts the pulse wave signal from the cuff pressure signal detected by the pressure sensor 31, attempts to calculate the systolic blood pressure and the diastolic blood pressure based on the pulse wave signal, and determines whether the blood pressure calculation is completed (step S30). If the blood pressure calculation cannot be completed due to insufficient data (no in step S30), the processor 110 returns to step S28. If the blood pressure calculation is completed (yes in step S30), the processor 110 performs the following control: fully open the valve 33 (step S32) to quickly discharge the air in the cuff 20. The processor 110 displays the blood pressure value (measurement result) measured in step S30 on the display 50 (step S34).

[0098] Next, the case where the measurement mode is the arrhythmia determination mode (No in step S24) is described. The processor 110 sets the decompression speed G1 to a predetermined speed (e.g., 4 mmHg / s) (step S40). The predetermined speed is set to be sufficiently slower than the decompression speed G2. The processor 110 controls the valve 33 to gradually open according to the decompression speed G1 (step S42). Thus, the process of pressurization is changed to the process of decompression, and the cuff pressure is gradually reduced according to the decompression speed G1.

[0099] The processor 110 extracts the pulse wave signal from the cuff pressure signal during the decompression process, attempts to calculate the systolic blood pressure and the diastolic blood pressure based on the pulse wave signal, and determines whether the blood pressure calculation is completed (step S44). If the blood pressure calculation cannot be completed (no in step S44), the processor 110 returns to step S42. If the blood pressure calculation is completed (yes in step S44), the processor 110 performs arrhythmia determination processing (step S46). Specifically, the processor 110 determines whether arrhythmia occurs based on the pulse wave interval obtained from the pulse wave signal during the decompression process.

[0100] Next, the processor 110 executes the above-mentioned steps S32 and S34. It should be noted that in step S34, the blood pressure measurement result and the arrhythmia determination result are displayed as the measurement results.

[0101] Figure 7 This is a flowchart showing another example of the processing procedure of the sphygmomanometer 100 according to the first embodiment. Figure 7 The flowchart is equivalent to Figure 6 The flowchart is obtained by replacing step S40 in the flowchart of FIG. 1 with step S50. Therefore, detailed description of the processes other than step S50 will not be repeated.

[0102] Reference Figure 7 In step S50, the processor 110 calculates the decompression speed G1 based on the amplitude of the pulse wave signal during the pressurization process (ie, the pulse wave amplitude). Figure 4 The decompression rate G1 is calculated from the curve graph.

[0103] Figure 8 This is a flowchart showing another example of the processing procedure of the sphygmomanometer 100 according to the first embodiment. Figure 8 The flowchart is equivalent to Figure 6 The flowchart of FIG. 1 is obtained by replacing step S40 in the flowchart of FIG. 1 with step S60. Therefore, detailed description of the processes other than step S60 will not be repeated.

[0104] Reference Figure 8In step S60, the processor 110 calculates the decompression speed G1 based on the pulse wave amplitude obtained in the past. For example, the processor 110 calculates the decompression speed G1 according to Figure 5 The decompression rate G1 is calculated from the curve graph.

[0105] <Implementation Method 2>

[0106] In the second embodiment, a method of setting the decompression speed G1 by focusing on the size of the cuff (for example, the capacity of the fluid bladder) will be described.

[0107] In order to accurately measure blood pressure, it is necessary to appropriately compress and close the artery of the measured part by the cuff pressure. Therefore, the size of the cuff is determined according to the circumference of the measured part. The longer the circumference of the measured part, the larger the size of the cuff. When the size of the cuff becomes larger, the capacity of the fluid bag becomes larger, so the ratio of the capacity change of the fluid bag to the volume change of the artery becomes smaller. As a result, the change of the cuff pressure, that is, the amplitude of the pulse wave signal (i.e., the pulse wave amplitude), becomes smaller. The following is an explanation of the setting method of the decompression speed G1 of the second embodiment.

[0108] (Functional composition)

[0109] use Figure 3 The functional structure of the blood pressure meter 100 according to the second embodiment will be described using a block diagram. The blood pressure measurement unit 220 according to the second embodiment has Figure 3 In addition to the functions described in , it also has the following functions.

[0110] The blood pressure measuring unit 220 drives the pump 32 to pressurize the cuff in a manner that the discharge flow rate per unit time is constant during the pressurization process. The blood pressure measuring unit 220 measures the reaching time T until the cuff pressure reaches the specified pressure during the pressurization process based on the cuff pressure signal detected by the pressure sensor 31. The reaching time T varies depending on the capacity (size) of the cuff. For example, the blood pressure measuring unit 220 measures the reaching time T until the cuff pressure reaches "30 mmHg" from "0 mmHg". The longer the reaching time T, the slower the blood pressure measuring unit 220 sets the decompression speed G1.

[0111] Fig. 9 This is a diagram for explaining the relationship between the time required to reach a predetermined pressure and the decompression rate. Fig. 9 The vertical axis of the graph represents the decompression speed G1, and the horizontal axis represents the reaching time T for the cuff pressure to reach "30 mmHg" from "0 mmHg".

[0112] like Fig. 9 As shown in the graph of , it can be seen that the longer the reaching time T is, the slower the decompression speed G1 is. This is to perform high-precision arrhythmia determination by obtaining a pulse wave amplitude having a certain magnitude or greater during the decompression process.

[0113] Specifically, since the pump 32 is driven to pressurize the cuff in such a manner that the discharge flow rate per unit time is constant, the longer the arrival time T is, the larger the capacity of the cuff (i.e., the size of the cuff) is. In addition, as described above, the larger the size of the cuff is, the smaller the pulse wave amplitude is. Therefore, the longer the arrival time T is (i.e., the larger the size of the cuff is), the slower the decompression speed G1 is set, thereby increasing the pulse wave amplitude obtained during the decompression process. As a result, high-precision arrhythmia determination can be achieved.

[0114] It should be noted that the blood pressure measurement unit 220 may be configured to estimate the size of the cuff based on the reaching time T. Fig.10 This is a diagram for explaining the relationship between the time required to reach a predetermined pressure, the decompression rate, and the cuff size. Fig.10 The vertical axis of the graph is the decompression speed G1, and the horizontal axis is the reaching time T.

[0115] The blood pressure measurement unit 220 estimates the cuff size as "Small" when the arrival time T is less than 3 seconds, estimates the cuff size as "Medium" when the arrival time T is more than 3 seconds and less than 6 seconds, and estimates the cuff size as "Large" when the arrival time T is more than 6 seconds. That is, the longer the arrival time T is, the larger the cuff size is estimated by the blood pressure measurement unit 220.

[0116] Furthermore, the blood pressure measurement unit 220 sets the decompression speed G1 to 6 mmHg / s when the cuff size is estimated to be "small", sets the decompression speed G1 to 5.5 mmHg / s when the cuff size is estimated to be "medium", and sets the decompression speed G1 to 4 mmHg / s when the cuff size is estimated to be "large". That is, the larger the cuff size, the slower the decompression speed G1 is set by the blood pressure measurement unit 220.

[0117] (Processing process)

[0118] Fig.11 This is a flowchart showing an example of a processing procedure of the sphygmomanometer 100 according to the second embodiment. Fig.11 The flowchart is equivalent to Figure 6 The flowchart of step S40 in the flowchart of is replaced by step S70. Therefore, the processing other than step S70 will not be repeatedly described in detail. However, in step S16, the processor 110 controls the pump drive circuit 320 to drive the pump 32 in a manner that the discharge flow rate per unit time is constant in order to increase the pressure.

[0119] Reference Fig.11In step S70, the processor 110 calculates the decompression speed G1 based on the time T taken for the cuff pressure to reach the specified pressure during the pressurization process. Fig. 9 The decompression rate G1 is calculated from the curve graph.

[0120] Fig.12 This is a flowchart showing another example of the processing procedure of the sphygmomanometer 100 according to the second embodiment. Fig.12 The flowchart is equivalent to Figure 6 The flowchart of FIG. 1 is obtained by replacing step S40 in the flowchart with steps S80 and S82. Therefore, the processing other than steps S80 and S82 will not be repeatedly described in detail. However, in step S16, the processor 110 controls the pump drive circuit 320 to drive the pump 32 in a manner that the discharge flow rate per unit time is constant in order to increase the pressure.

[0121] Reference Fig.12 The processor 110 estimates the cuff size based on the reaching time T (step S80), and calculates the decompression speed G1 based on the estimated cuff size (step S82). Fig.10 The cuff size is estimated based on the curve graph and the decompression speed G1 is calculated.

[0122] <Implementation Method 3>

[0123] In the third embodiment, a method of setting the decompression speed G1 by focusing on the degree of tightening of the cuff will be described.

[0124] When the cuff is loosely wound, the fluid bag needs to be over-inflated until the gap between the biological body and the cuff is filled. Therefore, when the cuff is loosely wound, the capacity of the fluid bag becomes larger than when the cuff is moderately wound, and as a result, the amplitude of the obtained pulse wave signal becomes smaller. The following describes the setting method of the decompression speed G1 of the third embodiment.

[0125] (Functional composition)

[0126] Fig.13 2 is a block diagram showing the functional configuration of the sphygmomanometer 100 according to the third embodiment. Fig.13 The sphygmomanometer 100 includes a mode setting unit 210, a blood pressure measuring unit 220, a determination unit 230, an output control unit 240, and a winding strength detection unit 260. These functions are realized by, for example, causing the processor 110 of the sphygmomanometer 100 to execute a program stored in the memory 51. The functions of the mode setting unit 210, the determination unit 230, and the output control unit 240 are similar to those of the embodiment of the present invention. Figure 3 The same function as described in .

[0127] The wrapping strength detection unit 260 detects the wrapping strength of the cuff 20 with respect to the measured part based on the cuff pressure during the pressurization process and the volume change of the cuff 20. The wrapping strength detection method is implemented by a well-known method. Typically, the wrapping strength detection unit 260 has the same function as the wrapping strength detection unit shown in Japanese Patent No. 5408142.

[0128] As an example, during the pressurization process of driving the pump 32 to pressurize the cuff so as to keep the discharge flow rate constant, the winding strength detecting unit 260 compares the value of the volume change of the cuff 20 detected accompanying the change of the cuff pressure from pressure P1 to pressure P2 with the value of the volume change of the cuff 20 detected accompanying the change of the cuff pressure from pressure P2 to pressure P3 based on the pressure-volume change relationship represented by the volume change of the cuff 20 detected accompanying the change of the cuff pressure from pressure P1 to pressure P2 and the volume change of the cuff 20 detected accompanying the change of the cuff pressure from pressure P2 to pressure P3, and detects the winding strength of the cuff 20 based on the comparison result.

[0129] Pressures P1, P2, and P3 are cuff pressures suitable for detecting the wrapping strength of the cuff, which are determined in advance by experiments, etc. The times when the cuff pressures reach pressures P1 to P3 are referred to as times V1 to V3, respectively.

[0130] In this case, the wrapping strength detection unit 260 calculates a change ΔP12 as a difference from pressure P1 to pressure P2 and a time ΔV12 indicating the time required for the cuff pressure change ΔP12 (i.e., time V2-V1). The time ΔV12 is proportional to the change in the fluid volume in the cuff when the pressure changes from pressure P1 to pressure P2. The wrapping strength detection unit 260 calculates a change ΔP23 as a difference from pressure P2 to pressure P3 and a time ΔV23 indicating the time required for the cuff pressure change ΔP23 (i.e., time V3-V2). The time ΔV23 is proportional to the change in the fluid volume in the cuff when the pressure changes from pressure P2 to pressure P3.

[0131] The winding strength detection unit 260 calculates the pressure-volume change indexes ΔP12 / ΔV12 and ΔP23 / ΔV23, and compares the calculated values. Based on the comparison result, the winding strength detection unit 260 detects the winding strength.

[0132] When the comparison result is (ΔP12 / ΔV12)<(ΔP23 / ΔV23), the wrapping strength detection unit 260 detects that the wrapping strength of the cuff 20 is “loosely wrapped”. When the comparison result is (ΔP12 / ΔV12)>(ΔP23 / ΔV23), the wrapping strength detection unit 260 detects that the wrapping strength of the cuff 20 is “tightly wrapped”. When the comparison result is (ΔP12 / ΔV12)=(ΔP23 / ΔV23), the wrapping strength detection unit 260 detects that the wrapping strength of the cuff 20 is “moderately wrapped”.

[0133] “Loosely wrapped” refers to a wrapped state in which the cuff 20 is loosely wrapped around the measured part, so that the pressure applied to the measured part is lower than the appropriate level. “Appropriately wrapped” refers to a wrapped state in which the cuff 20 is appropriately wrapped around the measured part, so that the pressure applied to the measured part is at an appropriate level. “Tightly wrapped” refers to a wrapped state in which the cuff 20 is tightly wrapped around the measured part, so that the pressure applied to the measured part is higher than the appropriate level.

[0134] The smaller the winding strength detected by the winding strength detection unit 260, the slower the decompression speed G1 is set by the blood pressure measurement unit 220. For example, for convenience, the decompression speed G1 when the winding strength is "loose winding" is set to "G1a", the decompression speed G1 when the winding strength is "moderate winding" is set to "G1b", and the decompression speed G1 when the winding strength is "tight winding" is set to "G1c". In this case, the decompression speed G1a is the slowest, the decompression speed G1c is the fastest, and the decompression speed G1b is in between them (i.e., G1a is the slowest). <G1b<G1c)。

[0135] (Processing process)

[0136] Fig.14 This is a flowchart showing an example of a processing procedure of the sphygmomanometer 100 according to the third embodiment. Fig.14 The flowchart is equivalent to Figure 6 The flowchart is obtained by replacing step S40 in the flowchart with steps S90, S92, S94, and S96. Therefore, the processing other than steps S90, S92, S94, and S96 will not be repeatedly described in detail. However, in step S16, the processor 110 controls the pump drive circuit 320 to drive the pump 32 in order to increase the pressure so that the discharge flow rate per unit time is constant.

[0137] Reference Fig.14, the processor 110 detects the wrapping strength of the cuff 20 relative to the measured part (step S90). The processor 110 determines whether the detected wrapping strength is "moderately wrapped" or above (i.e., "moderately wrapped" or "tightly wrapped") (step S92). When the wrapping strength is "moderately wrapped" or above (yes in step S92), the processor 110 calculates the decompression speed G1 based on the estimated pulse pressure and pulse rate, which are the difference between the estimated systolic blood pressure and the estimated diastolic blood pressure (step S96). When the wrapping strength is "loosely wrapped" (no in step S92), the processor 110 sets the decompression speed G1 to a specified speed (for example, 4 mmHg / s) (step S94).

[0138] exist Fig.14 In the flowchart of, the configuration in which the decompression speed G1 is calculated based on the estimated pulse pressure and pulse rate in the same calculation method as the general mode when the winding strength is "moderate winding" or more is described, but the configuration is not limited to this configuration. For example, the decompression speed G1 may be set to the above-mentioned decompression speeds G1a to G1c according to the winding strength ("loose winding", "moderate winding" or "tight winding").

[0139] <Other Implementation Methods>

[0140] (1) In the above embodiment, a program for causing a computer to function to execute the control described in the above flowchart can also be provided. Such a program can be recorded on a non-temporary computer-readable recording medium such as a floppy disk, a CD-ROM (Compact Disc Read Only Memory), a secondary storage device, a main storage device, and a memory card attached to the computer, and provided as a program product. Alternatively, the program can be provided by recording on a recording medium such as a hard disk built into the computer. In addition, the program can also be provided by downloading via a network.

[0141] (2) The configurations illustrated as examples in the above-mentioned embodiments are examples of the configurations of the present invention, and can be combined with other known technologies, or can be modified by omitting a portion of the configurations without departing from the gist of the present invention. In addition, in the above-mentioned embodiments, the processes and configurations described in other embodiments can be appropriately adopted for implementation.

[0142] [Note]

[0143] As described above, the present embodiment includes the following disclosures.

[0144] [Composition 1]

[0145] A sphygmomanometer (100) measures blood pressure by compressing a user's measured part with a cuff (20), the sphygmomanometer comprising: a blood pressure measuring unit (220) for measuring the user's blood pressure based on a pulse wave signal during a decompression process, wherein the cuff pressure representing the internal pressure of the cuff is pressurized to a pressure greater than a specified pressure and then the cuff pressure is decompressed; a determination unit (230) for determining whether the user has arrhythmia based on the pulse wave signal during the decompression process; and a mode setting unit (210) for setting either a first mode for executing the arrhythmia determination or a second mode for not executing the arrhythmia determination, wherein the blood pressure measuring unit makes a first decompression speed of the cuff pressure when the first mode is set slower than a second decompression speed of the cuff pressure when the second mode is set.

[0146] [Composition 2]

[0147] The blood pressure monitor according to Configuration 1, wherein the blood pressure measurement unit sets the first depressurization speed based on a pulse wave amplitude indicating an amplitude of a pulse wave signal during the pressurization process.

[0148] [Composition 3]

[0149] According to the blood pressure meter described in configuration 1, it also has a storage unit (250), which stores the pulse wave signal during the pressurization process or the decompression process when the blood pressure of the user is measured by the blood pressure measuring unit, and the blood pressure measuring unit sets the first decompression speed based on the pulse wave amplitude representing the amplitude of the pulse wave signal in the past stored in the storage unit.

[0150] [Composition 4]

[0151] The blood pressure monitor according to configuration 2 or 3, wherein the blood pressure measurement unit sets the first decompression rate to be slower as the pulse wave amplitude is smaller.

[0152] [Composition 5]

[0153] According to the sphygmomanometer of Configuration 1, the blood pressure measurement unit sets the first depressurization speed to be slower as the time taken for the cuff pressure to reach a predetermined pressure during the pressurization process is longer.

[0154] [Composition 6]

[0155] According to the blood pressure monitor described in configuration 1, the blood pressure measurement unit estimates the size of the cuff based on the time it takes for the cuff pressure to reach a specified pressure during the pressurization process, and the blood pressure measurement unit sets the first decompression speed slower as the estimated cuff size is larger.

[0156] [Composition 7]

[0157] According to the blood pressure meter described in configuration 1, the blood pressure meter also has a winding strength detection unit (260), which detects the winding strength of the cuff relative to the measured part of the user based on the cuff pressure and the volume change of the cuff during the pressurization process, and the smaller the winding strength is, the slower the blood pressure measurement unit sets the first decompression speed.

[0158] [Composition 8]

[0159] The sphygmomanometer according to any one of configurations 1 to 7, wherein the blood pressure measurement unit sets the second decompression speed based on an estimated pulse pressure that is a difference between an estimated systolic blood pressure and an estimated diastolic blood pressure and a predetermined pulse rate required to measure the blood pressure of the user.

[0160] [Composition 9]

[0161] A blood pressure measurement method is a blood pressure measurement method performed by a sphygmomanometer (100), wherein the sphygmomanometer measures the blood pressure by compressing a measured part of a user through a cuff (20), and the blood pressure measurement method comprises the following steps: measuring the blood pressure of the user based on a pulse wave signal during a decompression process, wherein the cuff pressure representing the internal pressure of the cuff is pressurized to a pressure greater than a specified pressure and then the cuff pressure is decompressed; determining whether the user has arrhythmia based on the pulse wave signal during the decompression process; and setting either a first mode for executing the determination of arrhythmia or a second mode for not executing the determination of arrhythmia, wherein a first decompression speed of the cuff pressure when the first mode is set is slower than a second decompression speed of the cuff pressure when the second mode is set.

[0162] The embodiments disclosed this time should be considered in all respects as illustrative and non-restrictive. The scope of the present invention is indicated by the claims rather than the above description, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0163] Description of Reference Numerals

[0164] 10: Main body; 20: Cuff; 22: Fluid bag; 30: Air system component; 31: Pressure sensor; 32: Pump; 33: Valve; 50: Display; 51: Memory; 52: Operation unit; 52A: Measurement switch; 52B: Mode selection switch; 53: Communication interface; 54: Power supply unit; 100: Sphygmomanometer; 110: Processor; 210: Mode setting unit; 220: Blood pressure measurement unit; 230: Judgment unit; 240: Output control unit; 250: Storage unit; 260: Winding strength detection unit; 310: A / D conversion circuit; 320: Pump drive circuit; 330: Valve drive circuit.

Claims

1. A sphygmomanometer that measures blood pressure by compressing a user's measured area with a cuff, the sphygmomanometer comprising: a blood pressure measuring unit that measures the blood pressure of the user based on a pulse wave signal during a decompression process in which a cuff pressure representing an internal pressure of the cuff is pressurized to a pressure greater than a predetermined pressure and then the cuff pressure is decompressed; a determination unit that determines whether the user has arrhythmia based on the pulse wave signal during the decompression process; and a mode setting unit for setting one of a first mode for executing the determination of the arrhythmia and a second mode for not executing the determination of the arrhythmia, The blood pressure measurement unit sets a first decompression rate of the cuff pressure when the first mode is set to be slower than a second decompression rate of the cuff pressure when the second mode is set to be slower.

2. The sphygmomanometer according to claim 1, wherein: The blood pressure measurement unit sets the first depressurization speed based on a pulse wave amplitude indicating an amplitude of a pulse wave signal during the pressurization process.

3. The sphygmomanometer according to claim 1, wherein: The sphygmomanometer further includes a storage unit that stores a pulse wave signal during the pressurization process or the depressurization process when the blood pressure of the user is measured by the blood pressure measurement unit. The blood pressure measurement unit sets the first decompression speed based on the pulse wave amplitude indicating the past amplitude of the pulse wave signal stored in the storage unit.

4. The sphygmomanometer according to claim 2 or 3, wherein: The blood pressure measurement unit sets the first decompression rate to be slower as the pulse wave amplitude is smaller.

5. The sphygmomanometer according to claim 1, wherein: The blood pressure measurement unit sets the first depressurization speed to be slower as the time until the cuff pressure reaches a predetermined pressure during the pressurization process is longer.

6. The sphygmomanometer according to claim 1, wherein: The blood pressure measurement unit estimates the size of the cuff based on the time it takes for the cuff pressure to reach a predetermined pressure during the pressurization process. The blood pressure measurement unit sets the first decompression rate to be slower as the estimated size of the cuff is larger.

7. The sphygmomanometer according to claim 1, wherein: The sphygmomanometer further includes a wrapping strength detection unit configured to detect a wrapping strength of the cuff around the measured part of the user based on the cuff pressure and a volume change of the cuff during the pressurization process. The blood pressure measurement unit sets the first decompression rate to be slower as the winding strength is smaller.

8. The sphygmomanometer according to any one of claims 1 to 3 and 5 to 7, wherein: The blood pressure measurement unit sets the second decompression speed based on an estimated pulse pressure that is a difference between an estimated systolic blood pressure and an estimated diastolic blood pressure and a predetermined pulse rate required for measuring the blood pressure of the user.

9. A blood pressure measurement method, comprising: using a sphygmomanometer, wherein the sphygmomanometer measures blood pressure by compressing a user's measured part with a cuff, the blood pressure measurement method comprising the following steps: measuring the blood pressure of the user based on a pulse wave signal during a decompression process, wherein the cuff pressure representing the internal pressure of the cuff is decompressed after a pressurization process in which a cuff pressure representing the internal pressure of the cuff is pressurized to a pressure greater than a predetermined pressure; determining whether the user has arrhythmia based on the pulse wave signal during the decompression process; as well as setting either a first mode in which the determination of arrhythmia is performed or a second mode in which the determination of arrhythmia is not performed, A first decompression rate of the cuff pressure when the first mode is set is slower than a second decompression rate of the cuff pressure when the second mode is set.

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