Sphygmomanometer and blood pressure measuring method

Abstract

To provide a sphygmomanometer capable of accurately determining irregular pulses by obtaining a number of pulse wave signals with a large amplitude when measuring blood pressure.SOLUTION: A sphygmomanometer is equipped with a blood pressure measuring unit for measuring blood pressure of a user on the basis of a pulse wave signal in a pressurizing process for pressurizing cuff pressure indicating internal pressure of a cuff mounted on a measured part of the user. The blood pressure measuring unit makes a pressurizing speed in a predetermined period in the pressurizing process slower than a pressurizing speed in a period other than the predetermined period in the pressurizing process. The predetermined period is set on the basis of a timing when an amplitude of the pulse wave signal is maximum in the pressurizing process, or a timing when the cuff presser becomes average blood pressure of the user in the pressurizing process. The sphygmomanometer is further equipped with a determination unit for determining irregular pulses of the user on the basis of the pulse wave signal in the pressurizing process.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to a blood pressure monitor and a blood pressure measurement method. [Background technology]

[0002] Conventionally, a technique for detecting atrial fibrillation using a signal acquired during the process of measuring blood pressure is known. For example, a blood pressure monitor according to Patent Document 1 (JP Patent Publication 2020-192322 A) determines atrial fibrillation based on data on the interval time of a pulse signal in the pressurization stage measurement data and data on the interval time of a pulse signal in the depressurization stage measurement data. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-192322 A Summary of the Invention [Problem to be solved by the invention]

[0004] As a method of determining arrhythmia using a blood pressure monitor based on the oscillometric method, a method of determining arrhythmia such as atrial fibrillation based on a pattern of pulse wave intervals acquired during the process of increasing or decreasing cuff pressure is known. For example, the rising point or maximum point of a pulse wave signal for each beat is detected as a characteristic 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, it is preferable that the amplitude of the acquired pulse wave signal is large. Therefore, in order to increase the accuracy of arrhythmia determination based on the pattern of the pulse wave interval, it is preferable to acquire many pulse wave signals with large amplitude.

[0005] In one aspect, the present disclosure aims to provide a blood pressure monitor and a blood pressure measurement method that are capable of accurately determining arrhythmia by acquiring many large-amplitude pulse wave signals during blood pressure measurement. [Means for solving the problem]

[0006] In one example of the present disclosure, a blood pressure monitor includes a blood pressure measurement unit that measures the user's blood pressure based on a pulse wave signal during a pressurization process in which a cuff pressure indicating an internal pressure of a cuff attached to a measurement site of the user is applied. The blood pressure measurement unit sets an inflation speed during a predetermined period of the pressurization process slower than an inflation speed during other periods of the pressurization process other than the predetermined period. The predetermined period is set based on a timing when the amplitude of the pulse wave signal becomes maximum during the pressurization process or a timing when the cuff pressure becomes the user's mean blood pressure during the pressurization process. The blood pressure monitor further includes a determination unit that determines an arrhythmia of the user based on the pulse wave signal during the pressurization process.

[0007] According to the above configuration, when blood pressure is measured by the pressure measurement method, arrhythmia can be determined with high accuracy by acquiring many pulse wave signals with large amplitude.

[0008] In another example of the present disclosure, the blood pressure measurement unit sets the predetermined period to a period from when the amplitude of the pulse wave signal becomes maximum during the pressurization process until a specified time has elapsed.

[0009] According to the above configuration, when blood pressure is measured by the pressure measurement method, a pulse wave signal with a large amplitude can be efficiently obtained.

[0010] In another example of the present disclosure, the blood pressure monitor further includes a storage unit that stores associated information that associates the cuff pressure and the pulse wave signal obtained during a previous blood pressure measurement of the user. The blood pressure measurement unit extracts the cuff pressure at the timing when the amplitude of the pulse wave signal during the pressurization process during the previous blood pressure measurement of the user is maximized based on the associated information, and sets the predetermined period as a period from the timing when the cuff pressure during the pressurization process during the current blood pressure measurement of the user reaches the extracted cuff pressure until a specified time has elapsed.

[0011] According to the above configuration, when measuring blood pressure using the pressure measurement method, a pulse wave signal with large amplitude can be efficiently obtained based on past measurement results of the user.

[0012] In another example of the present disclosure, the blood pressure monitor further includes a storage unit that stores the systolic blood pressure and the diastolic blood pressure of the user obtained during a previous blood pressure measurement of the user. The blood pressure measurement unit calculates a mean blood pressure based on the systolic blood pressure and the diastolic blood pressure, and sets the predetermined period as a period from when the cuff pressure reaches the mean blood pressure during the inflation process during the current blood pressure measurement of the user until a specified time has elapsed.

[0013] According to the above configuration, when measuring blood pressure using the pressure measurement method, a pulse wave signal with large amplitude can be efficiently obtained based on past measurement results of the user.

[0014] In another example of the present disclosure, the blood pressure measurement unit sets the inflation speed for a predetermined period of time to zero.

[0015] According to the above configuration, when blood pressure is measured by the pressure measurement method, a larger number of pulse wave signals with large amplitude can be obtained.

[0016] In another example of the present disclosure, a blood pressure monitor includes a blood pressure measurement unit that measures the user's blood pressure based on a pulse wave signal during a depressurization process in which the cuff pressure, which indicates the internal pressure of a cuff attached to a measurement site of the user, is increased to a pressure greater than a specified pressure, and then the cuff pressure is decreased. The blood pressure measurement unit makes the depressurization rate during a predetermined period of the depressurization process slower than the depressurization rate during other periods other than the predetermined period of the depressurization process. The predetermined period is set based on the timing when the amplitude of the pulse wave signal becomes maximum during the depressurization process, or the timing when the cuff pressure becomes the user's mean blood pressure during the depressurization process. The blood pressure monitor further includes a determination unit that determines arrhythmia of the user based on the pulse wave signal during the depressurization process.

[0017] According to the above configuration, when blood pressure is measured using the reduced pressure measurement method, arrhythmia can be determined with high accuracy by acquiring many pulse wave signals with large amplitude.

[0018] In another example of the present disclosure, the blood pressure measurement unit sets the predetermined period to a period from when the amplitude of the pulse wave signal becomes maximum during the depressurization process until a specified time has elapsed.

[0019] According to the above configuration, a pulse wave signal with large amplitude can be efficiently acquired when measuring blood pressure using the reduced pressure measurement method.

[0020] In another example of the present disclosure, the blood pressure monitor further includes a storage unit that stores associated information that associates the cuff pressure and the pulse wave signal obtained during a previous blood pressure measurement of the user. The blood pressure measurement unit extracts the cuff pressure at the timing when the amplitude of the pulse wave signal during the decompression process during the previous blood pressure measurement of the user is maximized based on the associated information, and sets the predetermined period as a period from the timing when the cuff pressure during the decompression process during the current blood pressure measurement of the user reaches the extracted cuff pressure until a specified time has elapsed.

[0021] According to the above configuration, when measuring blood pressure using the reduced pressure measurement method, a pulse wave signal with large amplitude can be efficiently obtained based on the user's past measurement results.

[0022] In another example of the present disclosure, the blood pressure monitor further includes a storage unit that stores the systolic blood pressure and the diastolic blood pressure of the user obtained during a previous blood pressure measurement of the user. The blood pressure measurement unit calculates a mean blood pressure based on the systolic blood pressure and the diastolic blood pressure, and sets the predetermined period as a period from when the cuff pressure reaches the mean blood pressure during the depressurization process during the current blood pressure measurement of the user until a specified time has elapsed.

[0023] According to the above configuration, when measuring blood pressure using the reduced pressure measurement method, a pulse wave signal with large amplitude can be efficiently obtained based on the user's past measurement results.

[0024] In another example of the present disclosure, the blood pressure measurement unit estimates the user's systolic blood pressure and diastolic blood pressure during the pressurization process, estimates a mean blood pressure based on the estimated systolic blood pressure and diastolic blood pressure, and sets the specified period as the period from the time when the cuff pressure during the depressurization process reaches the mean blood pressure to after a specified time has elapsed.

[0025] According to the above configuration, a pulse wave signal with large amplitude can be efficiently acquired when measuring blood pressure using the reduced pressure measurement method.

[0026] In another example of the present disclosure, the blood pressure measurement unit identifies the cuff pressure at the timing when the amplitude of the pulse wave signal is maximum during the pressurization process, and sets the predetermined period as the period from the timing when the cuff pressure during the depressurization process reaches the identified cuff pressure to a specified time after a specified amount of time has elapsed.

[0027] According to the above configuration, a pulse wave signal with large amplitude can be efficiently acquired when measuring blood pressure using the reduced pressure measurement method.

[0028] In another example of the present disclosure, the blood pressure measurement unit sets the depressurization rate for a predetermined period to zero.

[0029] According to the above configuration, when blood pressure is measured by the reduced pressure measurement method, a larger number of pulse wave signals with large amplitude can be obtained.

[0030] In another example of the present disclosure, a blood pressure measurement method includes a step of measuring a user's blood pressure based on a pulse wave signal during a pressurization process in which a cuff pressure indicating an internal pressure of a cuff attached to a measurement site of the user is applied. The measuring step includes making an inflation speed during a predetermined period of the pressurization process slower than an inflation speed during other periods other than the predetermined period of the pressurization process. The predetermined period is set based on a timing when the amplitude of the pulse wave signal becomes maximum during the pressurization process or a timing when the cuff pressure becomes the user's mean blood pressure during the pressurization process. The blood pressure measurement method further includes a step of determining an arrhythmia of the user based on the pulse wave signal during the pressurization process.

[0031] According to the above configuration, when blood pressure is measured by the pressure measurement method, arrhythmia can be determined with high accuracy by acquiring many pulse wave signals with large amplitude.

[0032] In another example of the present disclosure, the blood pressure measurement method includes a step of measuring the user's blood pressure based on the pulse wave signal in a depressurization process in which the cuff pressure, which indicates the internal pressure of a cuff attached to a measurement site of the user, is depressurized to a pressure greater than a specified pressure after a pressurization process. The measuring step includes making the depressurization rate in a predetermined period of the depressurization process slower than the depressurization rate in other periods other than the predetermined period of the depressurization process. The predetermined period is set based on the timing when the amplitude of the pulse wave signal becomes maximum in the depressurization process or the timing when the cuff pressure becomes the user's mean blood pressure in the depressurization process. The blood pressure measurement method further includes a determination unit that determines arrhythmia of the user based on the pulse wave signal in the depressurization process.

[0033] According to the above configuration, when blood pressure is measured using the reduced pressure measurement method, arrhythmia can be determined with high accuracy by acquiring many pulse wave signals with large amplitude. Effect of the Invention

[0034] According to the present disclosure, arrhythmia can be determined with high accuracy by acquiring many pulse wave signals with large amplitudes during blood pressure measurement. [Brief description of the drawings]

[0035] [Figure 1] FIG. 1 is a diagram showing a blood pressure monitor according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a block diagram illustrating an example of a hardware configuration of a sphygmomanometer. [Diagram 3] FIG. 2 is a block diagram showing the functional configuration of the sphygmomanometer. [Figure 4] FIG. 11 is a diagram showing the correspondence relationship between a pulse wave signal and cuff pressure during blood pressure measurement in normal mode (pressure measurement method). [Diagram 5] 13 is a flowchart showing an example of a blood pressure measurement process (pressurization measurement method) in a normal mode. [Figure 6] FIG. 11 is a diagram showing the correspondence relationship between a pulse wave signal and cuff pressure during blood pressure measurement in normal mode (depressurized measurement method). [Figure 7]13 is a flowchart showing blood pressure measurement processing (depressurization measurement method) in normal mode. [Figure 8] FIG. 11 is a diagram showing the correspondence relationship between the pulse wave signal and the cuff pressure during blood pressure measurement (pressure measurement method) in arrhythmia determination mode. [Figure 9] 13 is a flowchart showing blood pressure measurement processing (pressure measurement method) in an arrhythmia determination mode. [Figure 10] FIG. 11 is a diagram showing the correspondence relationship between the pulse wave signal and the cuff pressure during blood pressure measurement in arrhythmia determination mode (depressurization measurement method). [Figure 11] 13 is a flowchart showing blood pressure measurement processing (depressurization measurement method) in an arrhythmia determination mode. [Figure 12] 13 is a flowchart showing a first modification of the blood pressure measurement process (pressure measurement method) in the arrhythmia determination mode. [Figure 13] 13 is a flowchart showing a first modification of the blood pressure measurement process (depressurization measurement method) in the arrhythmia determination mode. [Figure 14] 13 is a flowchart showing a second modified example of the blood pressure measurement process (pressure measurement method) in the arrhythmia determination mode. [Figure 15] 13 is a flowchart showing a second modified example of the blood pressure measurement process (depressurization measurement method) in the arrhythmia determination mode. [Figure 16] 13 is a flowchart showing a third modified example of the blood pressure measurement process (depressurization measurement method) in the arrhythmia determination mode. [Figure 17] 13 is a flowchart showing a fourth modified example of the blood pressure measurement process (depressurization measurement method) in the arrhythmia determination mode. [Figure 18] FIG. 13 is a diagram showing the correspondence relationship between the pulse wave signal and the cuff pressure during blood pressure measurement (pressure measurement method) in the arrhythmia determination mode according to another embodiment. [Figure 19] FIG. 13 is a diagram showing the correspondence relationship between the pulse wave signal and the cuff pressure during blood pressure measurement (depressurization measurement method) in the arrhythmia determination mode according to another embodiment. [Figure 20] 13 is a flowchart showing a blood pressure measurement process (pressurization measurement method) in an arrhythmia determination mode according to another embodiment. [Figure 21] 13 is a flowchart showing a blood pressure measurement process (depressurization measurement mode) in an arrhythmia determination mode according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, the same components are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

[0037] [Example of application] An application example of the present invention will be described with reference to Fig. 1. Fig. 1 is a diagram showing a blood pressure monitor 100 according to the present embodiment.

[0038] With reference to FIG. 1, blood pressure monitor 100 is an upper arm blood pressure monitor that measures blood pressure by applying pressure to a measurement site of a user (i.e., a subject) with a cuff. Blood pressure monitor 100 performs blood pressure measurement by an oscillometric method. Blood pressure monitor 100 has a main body and a cuff (arm band) as main components. Note that blood pressure monitor 100 may be a wrist-type blood pressure monitor in which the main body and the cuff (arm band) are integrated. Hereinafter, the processing contents will be described with reference to FIG. 1.

[0039] 1, it is assumed that a user measures his / her own blood pressure using a blood pressure monitor 100. The blood pressure monitor 100 measures the user's blood pressure by a pressurization measurement method that measures blood pressure during the process of pressurizing a cuff, which indicates the internal pressure of a cuff attached to a measurement site (e.g., an arm) of the user.

[0040] The blood pressure monitor 100 starts inflating the cuff in response to a blood pressure measurement instruction from the user (corresponding to (1) in FIG. 1). It is assumed that the cuff inflation speed is set to a speed Va.

[0041] The blood pressure monitor 100 monitors the amplitude of the pulse wave signal (pulse wave amplitude) during the cuff pressure increase process (corresponding to (2) in FIG. 1). As the cuff pressure increases, the pulse wave amplitude gradually increases, reaches a maximum value, and then gradually decreases. In this way, the pulse wave amplitude is known to change in a mountain shape during the increase in pressure.

[0042] Next, the blood pressure monitor 100 changes the inflation speed based on the monitoring result of the pulse wave amplitude (corresponding to (3) in FIG. 1). For example, when the blood pressure monitor 100 determines that the pulse wave amplitude has reached a maximum, it changes the inflation speed to a speed Vb slower than speed Va. The blood pressure monitor 100 continues to inflate the cuff pressure at speed Vb until a certain period of time has elapsed from the time of the determination. After the certain period of time has elapsed, the blood pressure monitor 100 returns the inflation speed to speed Va and continues to inflate the cuff pressure.

[0043] The process of changing the inflation speed is a process for acquiring a sufficient number of pulse wave signals to accurately detect arrhythmia (e.g., atrial fibrillation) during blood pressure measurement. Typically, blood pressure monitor 100 determines whether arrhythmia has occurred based on the interval (pulse wave interval) of the pulse wave signals acquired during blood pressure measurement. Therefore, in order to perform this determination with high accuracy, it is preferable to acquire more pulse wave signals with large amplitudes. Therefore, blood pressure monitor 100 acquires more pulse wave signals with large amplitudes by slowing down the inflation speed during a period when a large pulse wave amplitude is obtained.

[0044] Then, the blood pressure monitor 100 calculates the user's blood pressure value and determines whether or not arrhythmia has occurred based on the pulse wave signal obtained during the pressurization process (corresponding to (4) in FIG. 1). In this case, the blood pressure monitor 100 displays the user's blood pressure value and the arrhythmia determination result on the display.

[0045] According to the above application example, in the inflation process, the cuff pressure is increased at a slow inflation speed during a period when the pulse wave amplitude is large, and at a normal inflation speed during other periods. This makes it possible to acquire more pulse wave signals with large amplitudes and efficiently obtain them, thereby enabling accurate determination of arrhythmia.

[0046] It is also known that the cuff pressure at the timing when the pulse wave amplitude is maximum is near the mean blood pressure of the user. Therefore, the period when the cuff pressure is near the mean blood pressure can be said to be a period when the pulse wave amplitude is large. Therefore, when the blood pressure monitor 100 determines that the cuff pressure has reached the mean blood pressure of the user, the inflation speed may be changed to a speed Vb slower than the speed Va. In this case, since the inflation speed is slow during the period when the cuff pressure is near the mean blood pressure, many pulse wave signals with large amplitude can be obtained.

[0047] [Configuration example] <Hardware configuration> Fig. 2 is a block diagram showing an example of a hardware configuration of the blood pressure monitor 100. Referring to Fig. 2, the blood pressure monitor 100 includes, as main components, a main body 10 and a cuff 20. The cuff 20 contains a fluid bag 22. 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.

[0048] The processor 110 is an arithmetic processing unit such as a CPU (Central Processing Unit) or an MPU (Multi Processing Unit). The processor 110 realizes each of the 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 of the pump 32 and the valve 33 in response to an operation signal from the operation unit 52. The processor 110 also calculates a blood pressure value using an algorithm for calculating blood pressure by the oscillometric method, and displays the calculated blood pressure value on the display 50.

[0049] The memory 51 is realized 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 used for controlling the sphygmomanometer 100, setting data for setting various functions of the sphygmomanometer 100, and data of blood pressure measurement results, pulse rate, pulse wave interval, etc. The memory 51 is also used as a work memory, etc. when the program is executed.

[0050] The air system component 30 supplies or exhausts air through air piping to the fluid bag 22 contained in the cuff 20. The air system component 30 includes a pressure sensor 31 for detecting the pressure inside the fluid bag 22, and a pump 32 and a valve 33 as an inflation / deflation mechanism for inflating and deflating the fluid bag 22.

[0051] 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 piezo-resistance type pressure sensor, and is connected to the pump 32, the valve 33, and the fluid bag 22 contained in the cuff 20 via an air pipe. The pump 32 supplies air as a fluid to the fluid bag 22 through the air pipe to increase the cuff pressure. The valve 33 is opened and closed to control the cuff pressure by discharging air from the fluid bag 22 through the air pipe or by sealing air in the fluid bag 22.

[0052] The A / D conversion circuit 310 converts the output value of the pressure sensor 31 (for example, a voltage value corresponding to a change in electrical resistance due to the piezoresistance effect) from an analog signal to a digital signal and outputs it to the processor 110. The processor 110 acquires a signal representing the cuff pressure according to 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 provided by the processor 110. The valve drive circuit 330 controls the opening and closing of the valve 33 based on a control signal provided by the processor 110.

[0053] The processor 110 performs blood pressure measurement using a pressurization measurement method in which the user's blood pressure is measured based on the pulse wave signal during a pressurization process in which the cuff pressure is increased, or a depressurization measurement method in which the user's blood pressure is measured based on the pulse wave signal during a depressurization process in which the cuff pressure is reduced after a pressurization process in which the cuff pressure is increased to a pressure greater than a specified pressure (e.g., the "estimated systolic blood pressure" described below).

[0054] For example, when a measurement is performed using the reduced pressure measurement method, the following operation is generally performed. A cuff is wrapped around the user's measurement site (wrist, arm, etc.) in advance, and when a measurement is performed, pump 32 and valve 33 are controlled to increase the cuff pressure higher than the estimated systolic blood pressure, and then the pressure is gradually reduced. During this reduction process, the cuff pressure is detected by pressure sensor 31, and the change in arterial volume occurring in the artery at the measurement site is extracted as a pulse wave signal. The maximum blood pressure (systolic blood pressure) and minimum blood pressure (diastolic blood pressure) are calculated based on the change in amplitude of the pulse wave signal (mainly the rise and fall) accompanying the change in cuff pressure at that time.

[0055] The operation unit 52 inputs an operation signal corresponding to an instruction from a user to the processor. The operation unit 52 includes a measurement switch 52A for receiving a blood pressure measurement instruction from the user, and a mode selection switch 52B for selecting a measurement mode.

[0056] When the measurement switch 52A is pressed, the measurement site is temporarily compressed by the cuff 20, and blood pressure measurement is performed by the oscillometric method. When the measurement switch 52A is pressed again during blood pressure measurement, the blood pressure measurement is stopped.

[0057] 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 measurement mode (hereinafter also simply referred to as the "normal mode"), pressing the mode selection switch 52B switches the measurement mode to the arrhythmia determination mode.

[0058] 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 each piece of hardware.

[0059] <Functional configuration> FIG. 3 is a block diagram showing a functional configuration of the sphygmomanometer 100. Referring to FIG. 3, the sphygmomanometer 100 includes, as main functional components, a mode setting unit 210, a blood pressure measurement unit 220, a determination unit 230, and an output control unit 240. These functions are realized, for example, by the processor 110 of the sphygmomanometer 100 executing a program stored in the memory 51. Note that some or all of these functions may be configured to be realized by hardware. The sphygmomanometer 100 further includes a storage unit 250. The storage unit 250 is realized by the memory 51.

[0060] The mode setting unit 210 sets either an arrhythmia determination mode in which the presence or absence of arrhythmia of the user is determined, or a normal mode in which arrhythmia determination is not performed. Typically, the mode setting unit 210 sets either the arrhythmia determination mode or the normal mode in accordance with a mode selection instruction from the user via the operation unit 52 (e.g., the mode selection switch 52B).

[0061] 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 zone 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 zone other than time zone H of a day, the normal mode is automatically set.

[0062] The blood pressure measurement unit 220 controls the cuff pressure according to a measurement start instruction from the user via the operation unit 52 (e.g., measurement switch 52A). Specifically, the blood pressure measurement unit 220 drives the pump 32 via the pump drive circuit 320, and controls the drive of the valve 33 via the valve drive circuit 330. The valve 33 is opened and closed to discharge or seal air in the fluid bag 22 to control the cuff pressure.

[0063] The blood pressure measurement unit 220 receives the cuff pressure signal detected by the pressure sensor 31 and extracts a pulse wave signal representing the pulse wave at the measurement site superimposed on the cuff pressure signal. That is, the blood pressure measurement unit 220 detects, from the cuff pressure signal, a pulse wave, which is a pressure component that is superimposed on the cuff pressure signal in synchronization with the beating of the user's heart.

[0064] The blood pressure measurement unit 220 calculates blood pressure information of the user based on the cuff pressure signal and the pulse wave signal superimposed on the cuff pressure signal. Specifically, the blood pressure measurement unit 220 measures the user's blood pressure by a pressurized measurement method or a depressurized measurement method according to the oscillometric method. Typically, the blood pressure measurement unit 220 calculates systolic blood pressure, diastolic blood pressure, pulse rate, pulse pressure, etc. The storage unit 250 stores information obtained during blood pressure measurement (e.g., cuff pressure, pulse wave signal, systolic blood pressure, diastolic blood pressure, pulse rate, pulse pressure, etc.).

[0065] Here, it is assumed that the measurement mode is set to the normal mode by the mode setting unit 210. In this case, when performing blood pressure measurement using the pressurization measurement method, the blood pressure measurement unit 220 keeps the pressurization speed constant during the pressurization process. Also, when performing blood pressure measurement using the depressurization measurement method, the blood pressure measurement unit 220 keeps the depressurization speed constant during the depressurization process.

[0066] It is assumed that the measurement mode has been set to the arrhythmia determination mode by the mode setting unit 210. First, a case where the blood pressure measurement unit 220 performs blood pressure measurement by the pressurization measurement method will be described.

[0067] When blood pressure measurement is performed using the inflation measurement method, the blood pressure measurement unit 220 sets the inflation speed during a period Tb of the inflation process to be slower than the inflation speed during periods Ta other than the period Tb in the inflation process. The period Tb is set based on the timing at which the amplitude of the pulse wave signal becomes maximum during the inflation process, or the timing at which the cuff pressure becomes the user's mean blood pressure during the inflation process.

[0068] In one aspect, blood pressure measurement unit 220 sets, as period Tb, the period from the timing at which the amplitude of the pulse wave signal becomes maximum during the pressurization process until a specified time has elapsed.

[0069] In another aspect, the blood pressure measurement unit 220 sets the period Tb based on related information stored in the storage unit 250. Specifically, the storage unit 250 stores related information that associates the cuff pressure and the pulse wave signal obtained during a previous blood pressure measurement of the user. For example, the related information includes information indicating the correspondence relationship between the cuff pressure and the pulse wave signal during the inflation process or the depressurization process when the user's blood pressure is measured.

[0070] Based on the related information, the blood pressure measurement unit 220 extracts the cuff pressure at the timing when the amplitude of the pulse wave signal during the inflation process during the previous blood pressure measurement of the user is maximum. The blood pressure measurement unit 220 sets the period from the timing when the cuff pressure during the inflation process during the current blood pressure measurement of the user reaches the extracted cuff pressure to a specified time after the passage of time as the period Tb.

[0071] In still another aspect, the blood pressure measurement unit 220 sets the period Tb based on the mean blood pressure of the user. Specifically, the storage unit 250 stores the systolic blood pressure and diastolic blood pressure of the user obtained during past blood pressure measurements of the user. The blood pressure measurement unit 220 calculates the mean blood pressure based on the systolic blood pressure and diastolic blood pressure stored in the storage unit 250. For example, the blood pressure measurement unit 220 calculates the mean blood pressure based on the relational expression "mean blood pressure = diastolic blood pressure + (systolic blood pressure - diastolic blood pressure) ÷ 3". The blood pressure measurement unit 220 sets the period Tb as a period from the timing when the cuff pressure reaches the mean blood pressure during the pressurization process during the current blood pressure measurement of the user to the time when a specified time has elapsed.

[0072] The blood pressure measurement unit 220 may set the inflation speed during the period Tb of the inflation process to zero. That is, the blood pressure measurement unit 220 may stop increasing the cuff pressure during the period Tb to maintain the cuff pressure constant.

[0073] Next, a case will be described in which the arrhythmia determination mode is set and the blood pressure measurement unit 220 performs blood pressure measurement by the depressurization measurement method. In this case, the blood pressure measurement unit 220 sets the depressurization speed during the period Tg of the depressurization process slower than the depressurization speed during other periods Tf other than the period Tg in the depressurization process. The period Tg is set based on the timing when the amplitude of the pulse wave signal becomes maximum during the depressurization process, or the timing when the cuff pressure becomes the user's mean blood pressure during the depressurization process.

[0074] In one aspect, blood pressure measurement section 220 sets, as period Tg, the period from the timing at which the amplitude of the pulse wave signal becomes maximum during the depressurization process until a specified time has elapsed.

[0075] In another aspect, the blood pressure measurement unit 220 extracts the cuff pressure at the timing when the amplitude of the pulse wave signal during the depressurization process during the previous blood pressure measurement of the user is maximum, based on the related information stored in the storage unit 250. The blood pressure measurement unit 220 sets the period from the timing when the cuff pressure during the depressurization process during the current blood pressure measurement of the user reaches the extracted cuff pressure to a specified time after the passage of time as the period Tg.

[0076] In still another aspect, the blood pressure measurement unit 220 sets the period Tg based on the mean blood pressure of the user. Specifically, the blood pressure measurement unit 220 calculates the mean blood pressure based on the systolic blood pressure and the diastolic blood pressure stored in the storage unit 250. The blood pressure measurement unit 220 sets the period Tg to a period from the timing when the cuff pressure reaches the mean blood pressure during the depressurization process during the current blood pressure measurement of the user to the time when a specified time has elapsed.

[0077] In still another aspect, the blood pressure measurement unit 220 estimates the systolic blood pressure and diastolic blood pressure of the user during the pressurization process of the depressurization measurement method, and estimates the mean blood pressure based on the estimated systolic blood pressure (hereinafter also referred to as the "estimated systolic blood pressure") and diastolic blood pressure (hereinafter also referred to as the "estimated diastolic blood pressure") (i.e., calculates the estimated mean blood pressure). The estimation of the systolic blood pressure and the diastolic blood pressure is performed by a known method. For example, the blood pressure measurement unit 220 estimates the systolic blood pressure and the diastolic blood pressure from a pulse wave envelope that indicates a pattern of the amplitude change of the pulse wave signal that changes during the process of increasing the cuff pressure. The blood pressure measurement unit 220 calculates the estimated mean blood pressure based on the relational expression "estimated mean blood pressure = estimated diastolic blood pressure + (estimated systolic blood pressure - estimated diastolic blood pressure) ÷ 3". The blood pressure measurement unit 220 sets the period from the timing when the cuff pressure reaches the estimated mean blood pressure during the depressurization process until a specified time has elapsed as the period Tg.

[0078] In still another aspect, the blood pressure measurement unit 220 specifies the cuff pressure at the timing when the amplitude of the pulse wave signal becomes maximum during the inflation process of the depressurization measurement method. The blood pressure measurement unit 220 sets the period from the timing when the cuff pressure during the depressurization process reaches the specified cuff pressure to the time after a specified time has elapsed as the period Tg.

[0079] The blood pressure measurement unit 220 may set the depressurization rate during the period Tg of the depressurization process to zero. That is, the blood pressure measurement unit 220 may maintain the cuff pressure constant by stopping the depressurization of the cuff pressure during the period Tg.

[0080] The determination unit 230 performs arrhythmia determination when the arrhythmia determination mode is set. When the blood pressure measurement unit 220 performs blood pressure measurement using the pressurization measurement method, the determination unit 230 determines whether or not the user has experienced arrhythmia based on the pulse wave signal during the pressurization process. When the blood pressure measurement unit 220 performs blood pressure measurement using the depressurization measurement method, the determination unit 230 determines whether or not the user has experienced arrhythmia based on the pulse wave signal during the depressurization process. A known method is used for arrhythmia determination. For example, the determination unit 230 determines whether or not arrhythmia has occurred based on the occurrence interval of multiple pulse waves (i.e., pulse wave interval) acquired from the pulse wave signal.

[0081] 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. The output control unit 240 may transmit the measurement results and the determination results to an external device via the communication interface 53, or may be configured to output the results as audio via a speaker (not shown).

[0082] <Processing in normal mode> Fig. 4 is a diagram showing the correspondence relationship between the pulse wave signal and the cuff pressure during blood pressure measurement in normal mode (inflating measurement method). Referring to Fig. 4, blood pressure monitor 100 starts an inflation process and inflates the cuff at a constant speed (for example, speed Va). During the inflation process, the pulse wave amplitude gradually increases as the cuff pressure increases, reaches a maximum point, and then gradually decreases. Upon completion of blood pressure measurement, blood pressure monitor 100 stops pump 32 to end the inflation process and opens valve 33. This causes the cuff pressure to suddenly decrease.

[0083] FIG. 5 is a flowchart showing an example of a blood pressure measurement process (pressurization measurement method) in the normal mode.

[0084] 5, the processor 110 of the sphygmomanometer 100 initializes the pressure sensor 31 (step S12). Specifically, the processor 110 initializes the processing memory area, turns off (stops) the pump 32, and adjusts the pressure sensor 31 to 0 mmHg (sets the atmospheric pressure to 0 mmHg) with the valve 33 open.

[0085] Next, the processor 110 closes the valve 33 via the valve drive circuit 330 (step S14), and drives the pump 32 via the pump drive circuit 320 to start pressurizing the cuff 20 (fluid bag 22) (step S16). At this time, the processor 110 controls the inflation speed of the cuff pressure, which is the pressure inside the fluid bag 22, based on the output of the pressure sensor 31 while supplying air from the pump 32 to the fluid bag 22 through the air piping. This starts the pressurization process. The processor 110 controls the inflation speed to a constant speed (for example, speed Va).

[0086] Next, the processor 110 extracts a pulse wave signal from the cuff pressure signal detected by the pressure sensor 31, attempts to calculate the systolic blood pressure and diastolic blood pressure based on the pulse wave signal, and determines whether the blood pressure calculation is complete (step S18).

[0087] If the blood pressure calculation cannot be completed due to insufficient data (NO in step S18), the processor 110 repeats the processes of steps S16 and S18 unless the cuff pressure reaches a predetermined upper limit pressure (e.g., 300 mmHg). If the blood pressure calculation is completed (YES in step S18), the processor 110 stops the pump 32 (step S20) and opens the valve 33 (step S22) to exhaust the air from the cuff 20. The processor 110 displays the blood pressure value measured in the blood pressure measurement on the display 50 (step S24).

[0088] Fig. 6 is a diagram showing the correspondence relationship between the pulse wave signal and the cuff pressure during blood pressure measurement in normal mode (depressurization measurement method). Referring to Fig. 6, the sphygmomanometer 100 starts the pressurization process and pressurizes the cuff until the cuff pressure reaches a specified pressure (e.g., estimated systolic blood pressure). At this time, as the cuff pressure increases, the pulse wave amplitude increases and then decreases.

[0089] When the cuff pressure reaches a specified pressure, the blood pressure monitor 100 transitions from the inflation process to the depressurization process to reduce the cuff pressure. In the depressurization process, the pulse wave amplitude gradually increases as the cuff pressure decreases, reaches a maximum point, and then gradually decreases. When the blood pressure measurement is completed, the blood pressure monitor 100 ends the depressurization process and fully opens the valve 33.

[0090] FIG. 7 is a flowchart showing the blood pressure measurement process (depressurization measurement method) in the normal mode.

[0091] 7, the processes in steps S32 to S36 are similar to the processes in steps S12 to S16 in FIG. 5, respectively, and therefore detailed description thereof will not be repeated.

[0092] Processor 110 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 S38). Processor 110 then determines whether the cuff pressure reaches or exceeds threshold value Th (step S40). Typically, threshold value Th is set to a value that is a fixed value (e.g., 40 mmHg) higher than the estimated systolic blood pressure.

[0093] If the cuff pressure is less than the threshold value Th (NO in step S40), the processor 110 returns to step S36. If the cuff pressure is equal to or greater than the threshold value Th (YES in step S130), the processor 110 stops the pump 32 (step S42). The processor 110 calculates a decompression speed (e.g., speed Vf) based on the estimated pulse pressure, which is the difference between the estimated systolic blood pressure and the estimated diastolic blood pressure, and the pulse rate (step S44). Typically, the processor 110 sets the decompression speed so that the pulse rate occurring between the estimated pulse pressures is equal to or greater than a predetermined pulse rate.

[0094] The processor 110 controls the valve 33 to gradually open at a speed Vf (step S46). This causes a transition from the pressurization process to the depressurization process, and the cuff pressure is gradually reduced.

[0095] During this decompression process, processor 110 extracts a pulse wave signal from the cuff pressure signal detected by pressure sensor 31, and attempts to calculate the systolic blood pressure and the diastolic blood pressure based on the pulse wave signal to determine whether or not the blood pressure calculation is complete (step S48). If the blood pressure calculation is not complete (NO in step S48), processor 110 repeats the processes of steps S46 and S48. If the blood pressure calculation is complete (YES in step S48), processor 110 fully opens valve 33 (step S50) and performs control to rapidly exhaust the air in cuff 20. Processor 110 displays the blood pressure value measured in the blood pressure measurement on display 50 (step S52).

[0096] <Processing in arrhythmia determination mode> Fig. 8 is a diagram showing the correspondence relationship between the pulse wave signal and the cuff pressure during blood pressure measurement (inflating measurement method) in the arrhythmia determination mode. Referring to Fig. 8, sphygmomanometer 100 starts the inflation process and increases the cuff pressure at a constant inflation speed (for example, speed Va). During the inflation process, the pulse wave amplitude gradually increases as the cuff pressure increases, and reaches a maximum point.

[0097] When the blood pressure monitor 100 determines that the pulse wave amplitude has reached a maximum, it changes the inflation speed from speed Va to speed Vb (however, speed Vb is slower than speed Va). The speed change period during which the cuff pressure is increased at speed Vb is the period from the time of the determination to a specified time after the lapse of the specified time. The speed change period corresponds to the above-mentioned period Tb, and the period other than the speed change period during the inflation process corresponds to the above-mentioned period Ta.

[0098] When the period Tb ends, the blood pressure monitor 100 returns the inflation speed from speed Vb to speed Va to continue inflating the cuff. When the blood pressure measurement is completed, the pump 32 is stopped to end the inflation process and the valve 33 is opened. This causes the cuff pressure to decrease rapidly.

[0099] FIG. 9 is a flowchart showing the blood pressure measurement process (pressurization measurement method) in the arrhythmia determination mode.

[0100] 9, the processes of steps S102 to S106 are similar to the processes of steps S12 to S16 in FIG. 5, respectively, and therefore detailed description thereof will not be repeated. In step S106, processor 110 increases the cuff pressure at a speed Va (for example, 5.5 mmHg / s). This starts the pressurization process.

[0101] Processor 110 determines whether the pulse wave amplitude has reached a maximum during the pressurization process (step S108). For example, assume that the rate of change of the pulse wave amplitude is positive when the pulse wave amplitude is increasing, and is negative when the pulse wave amplitude is decreasing. In this case, processor 110 determines that the pulse wave amplitude has reached a maximum when the rate of change of the pulse wave amplitude changes from positive to negative.

[0102] If the pulse wave amplitude is not maximum (NO in step S108), processor 110 executes step S106 to continue inflating the cuff pressure at rate Va. If the pulse wave amplitude is maximum (YES in step S108), processor 110 changes the inflation rate from rate Va to rate Vb (e.g., 3 mmHg / s) (step S110).

[0103] Processor 110 determines whether a specified time has elapsed since changing the inflation speed to speed Vb (step S112). If the specified time has not elapsed (NO in step S112), processor 110 repeats the process of step S112. If the specified time has elapsed (YES in step S112), processor 110 returns the inflation speed from speed Vb to speed Va (step S114).

[0104] Processor 110 attempts to calculate the systolic blood pressure and the diastolic blood pressure based on the pulse wave signal during the pressurization process, and determines whether the blood pressure calculation is complete (step S116). If the blood pressure calculation cannot be completed due to insufficient data (NO in step S116), processor 110 repeats the process of step S116 unless the cuff pressure reaches a predetermined upper limit pressure (e.g., 300 mmHg). That is, processor 110 attempts to calculate the blood pressure while continuing to pressurize the cuff at speed Va.

[0105] When the blood pressure calculation is completed (YES in step S116), processor 110 executes arrhythmia determination processing (step S118). Specifically, processor 110 determines whether or not the user has experienced arrhythmia based on the pulse wave interval acquired from the pulse wave signal during the pressurization process. Processor 110 then executes the processing of steps S120 to S124. The processing of steps S120 to S124 is similar to the processing of steps S20 to S24 in FIG. 5, respectively, and therefore detailed description thereof will not be repeated. In step S124, processor 110 displays the arrhythmia determination result on display 50 together with the blood pressure value.

[0106] In the example of FIG. 9, the speed change period during which the cuff pressure is increased at speed Vb (that is, period Tb) is the period from the timing when the pulse wave amplitude becomes maximum until a specified time has elapsed.

[0107] The timing at which the inflation speed is changed from speed Va to speed Vb (i.e., the start timing of period Tb) may be set to a timing before the pulse wave amplitude is maximized. In this case, the start timing of period Tb may be set to a timing immediately before the rate of change in pulse wave amplitude changes from positive to negative (e.g., the time when the rate of positive change falls below a threshold).

[0108] Alternatively, the start timing of the period Tb may be set to a timing later than the timing when the pulse wave amplitude is maximum. In this case, the start timing of the period Tb may be set to a predetermined time (e.g., 1 second) after the timing when it is determined that the pulse wave amplitude is maximum.

[0109] Fig. 10 is a diagram showing the correspondence relationship between the pulse wave signal and the cuff pressure during blood pressure measurement in the arrhythmia determination mode (depressurization measurement method). Referring to Fig. 10, the blood pressure monitor 100 starts an inflation process and increases the cuff pressure at a constant inflation speed. When the cuff pressure reaches a specified pressure, the blood pressure monitor 100 transitions from the inflation process to a depressurization process and reduces the cuff pressure at a speed Vf. In the depressurization process, the pulse wave amplitude gradually increases as the cuff pressure decreases, and reaches a maximum point.

[0110] When the blood pressure monitor 100 determines that the pulse wave amplitude has reached a maximum, it changes the decompression speed from speed Vf to speed Vg (where speed Vg is sufficiently slower than speed Vf). The speed change period during which the cuff pressure is decompressed at speed Vf is the period from the time of the determination to a specified time after the lapse of the specified time. The speed change period corresponds to the above-mentioned period Tg, and the period other than the speed change period during the decompression process corresponds to the above-mentioned period Tf.

[0111] When the period Tg ends, the sphygmomanometer 100 returns the depressurization speed from speed Vg to speed Vf to continue depressurizing the cuff. When the blood pressure measurement is completed, the sphygmomanometer 100 ends the depressurization process and fully opens the valve 33.

[0112] FIG. 11 is a flowchart showing the blood pressure measurement process (depressurization measurement method) in the arrhythmia determination mode.

[0113] 11, the processes of steps S132 to S146 are similar to the processes of steps S32 to S46 in FIG 7, respectively, and therefore detailed description thereof will not be repeated. Note that in step S146, the processor 110 reduces the cuff pressure at a speed Vf, thereby starting the depressurization process.

[0114] The processor 110 determines whether the pulse wave amplitude has reached a maximum during the decompression process (step S148). If the pulse wave amplitude has not reached a maximum (NO in step S148), the processor 110 executes step S146 to continue decompressing the cuff pressure at the rate Vf. If the pulse wave amplitude has reached a maximum (YES in step S148), the processor 110 changes the decompression rate from rate Vf to rate Vg (e.g., 4 mmHg / s) (step S150). Rate Vg is sufficiently slower than rate Vf.

[0115] Processor 110 determines whether a specified time has elapsed since changing the depressurization speed to speed Vg (step S152). If the specified time has not elapsed (NO in step S152), processor 110 repeats the process of step S152. If the specified time has elapsed (YES in step S152), processor 110 returns the depressurization speed from speed Vg to speed Vf (step S154).

[0116] Processor 110 attempts to calculate the systolic blood pressure and the diastolic blood pressure based on the pulse wave signal during the depressurization process, and determines whether the blood pressure calculation is completed (step S156). If the blood pressure calculation cannot be completed (NO in step S156), processor 110 executes the process of step S156. That is, processor 110 attempts to calculate the blood pressure while continuing to reduce the cuff pressure at the rate Vf.

[0117] When the blood pressure calculation is completed (YES in step S156), the processor 110 executes an arrhythmia determination process (step S158). Then, the processor 110 fully opens the valve 33 (step S160) and displays the arrhythmia determination result together with the blood pressure value on the display 50 (step S162).

[0118] 11, the speed change period during which the cuff pressure is increased at the speed Vg (i.e., the period Tg) is the period from the timing when the pulse wave amplitude is maximized to a specified time after the lapse of the specified time. Note that the timing when the decompression speed is changed from the speed Vf to the speed Vg (i.e., the start timing of the period Tg) may be set to a timing before or after the timing when the pulse wave amplitude is maximized.

[0119] <Variation 1> FIG. 12 is a flowchart showing Modification 1 of the blood pressure measurement process (pressure measurement method) in the arrhythmia determination mode.

[0120] 12, the processes in steps S102 to S106 and S110 to S124 are similar to the corresponding processes in FIG. 9, and therefore detailed description thereof will not be repeated.

[0121] After the process of step S106, the processor 110 determines whether the cuff pressure being inflated has reached a cuff pressure corresponding to the maximum value of the pulse wave amplitude during the user's previous blood pressure measurement (step S180). Specifically, the processor 110 reads from the memory 51 related information indicating the relationship between the cuff pressure and the pulse wave amplitude during the previous blood pressure measurement (e.g., the previous measurement). The processor 110 extracts the cuff pressure at the timing when the pulse wave amplitude during the inflation process during the previous measurement is maximum (i.e., the maximum pulse wave amplitude is obtained) based on the related information. The processor 110 determines whether the cuff pressure during the inflation process during the current blood pressure measurement (i.e., the cuff pressure currently being inflated) has reached the extracted cuff pressure.

[0122] If the cuff pressure during inflation has not reached the extracted cuff pressure (NO in step S180), the processor 110 executes step S106. If the cuff pressure during inflation has reached the extracted cuff pressure (YES in step S180), the processor 110 changes the inflation speed from speed Va to speed Vb (e.g., 3 mmHg / s) (step S110).

[0123] 12, the speed change period (i.e., period Tb) during which the cuff pressure is increased at speed Vb is the period from the time when it is determined that the cuff pressure during the current measurement has reached the extracted cuff pressure until a specified time has elapsed. Note that in the above-mentioned step S180, the processor 110 may extract the cuff pressure at the timing at which a pulse wave amplitude is obtained that is a predetermined value smaller (or a predetermined value larger) than the maximum pulse wave amplitude during the inflation process during the previous measurement, based on the related information. However, the predetermined value is assumed to be a small value.

[0124] FIG. 13 is a flowchart showing Modification 1 of the blood pressure measurement process (depressurization measurement method) in the arrhythmia determination mode.

[0125] 13, the processes in steps S132 to S146 and S150 to S162 are similar to the corresponding processes in FIG. 11, and therefore will not be described in detail.

[0126] After processing step S146, processor 110 determines whether the cuff pressure being reduced has reached a cuff pressure corresponding to the maximum value of the pulse wave amplitude during the user's previous blood pressure measurement (step S190). Specifically, processor 110 reads from memory 51 related information indicating the relationship between the cuff pressure and the pulse wave amplitude during the previous blood pressure measurement (e.g., the previous measurement). Processor 110 extracts the cuff pressure at the timing when the pulse wave amplitude during the depressurization process during the previous measurement is maximum (i.e., the maximum pulse wave amplitude is obtained) based on the related information. Processor 110 determines whether the cuff pressure during the depressurization process during the current blood pressure measurement (i.e., the cuff pressure currently being depressurized) has reached the extracted cuff pressure.

[0127] If the cuff pressure during decompression has not reached the extracted cuff pressure (NO in step S190), the processor 110 executes step S146. If the cuff pressure during decompression has reached the extracted cuff pressure (YES in step S190), the processor 110 changes the decompression speed from speed Vf to speed Vg (e.g., 4 mmHg / s) (step S150).

[0128] 13, the speed change period during which the cuff pressure is increased at the speed Vg (i.e., the period Tg) is the period from the time when it is determined that the cuff pressure during the current measurement has reached the extracted cuff pressure until a specified time has elapsed. Note that in the above-mentioned step S190, the processor 110 may extract the cuff pressure at the timing when the pulse wave amplitude is obtained that is a predetermined value smaller (or a predetermined value larger) than the maximum pulse wave amplitude during the depressurization process during the previous measurement, based on the related information. However, the predetermined value is assumed to be a small value.

[0129] <Variation 2> FIG. 14 is a flowchart showing Modification 2 of the blood pressure measurement process (pressure measurement method) in the arrhythmia determination mode.

[0130] 14, the processes in steps S102, S104, S106, and S110 to S124 are similar to the corresponding processes in FIG. 9, and therefore detailed description thereof will not be repeated.

[0131] After the process of step S102, the processor 110 calculates the mean blood pressure based on the past blood pressure measurement values ​​(step S200). Specifically, the processor 110 reads out the systolic blood pressure and the diastolic blood pressure measured at the time of past blood pressure measurement (e.g., the previous measurement) from the memory 51, and calculates the mean blood pressure based on the systolic blood pressure and the diastolic blood pressure.

[0132] The processor 110 also starts increasing the cuff pressure by driving the pump 32 (step S106), and determines whether the cuff pressure has reached the mean blood pressure calculated in step S200 (step S210). If the cuff pressure has not reached the mean blood pressure (NO in step S210), the processor 110 executes step S106. If the cuff pressure has reached the mean blood pressure (YES in step S210), the processor 110 changes the inflation speed from speed Va to speed Vb (e.g., 3 mmHg / s) (step S110).

[0133] 14, the speed change period (i.e., period Tb) during which the cuff pressure is increased at speed Vb is a period from the time when it is determined that the cuff pressure has reached the mean blood pressure until a specified time has elapsed. Note that in the above-mentioned step S210, the processor 110 may determine whether the cuff pressure has reached a blood pressure that is a predetermined pressure lower (or a predetermined pressure higher) than the mean blood pressure. However, it is assumed that the predetermined pressure is a small value.

[0134] FIG. 15 is a flowchart showing Modification 2 of the blood pressure measurement process (depressurization measurement method) in the arrhythmia determination mode.

[0135] 15, the processes in steps S132, S134 to S146, and S150 to S162 are similar to the corresponding processes in FIG. 11, and therefore detailed description thereof will not be repeated.

[0136] After the process of step S132, the processor 110 calculates the mean blood pressure based on the past blood pressure measurement values ​​(step S220).

[0137] After the process of step S146, the processor 110 determines whether the cuff pressure during depressurization has reached the mean blood pressure calculated in step S220 (step S230). If the cuff pressure has not reached the mean blood pressure (NO in step S230), the processor 110 executes step S146. If the cuff pressure has reached the mean blood pressure (YES in step S230), the processor 110 changes the depressurization speed from speed Vf to speed Vg (for example, 4 mmHg / s) (step S150).

[0138] 15, the speed change period (i.e., period Tg) during which the cuff pressure is increased at the speed Vg is a period from the time when it is determined that the cuff pressure has reached the mean blood pressure until a specified time has elapsed. Note that in the above-mentioned step S210, the processor 110 may determine whether the cuff pressure has reached a blood pressure that is a predetermined pressure lower (or higher) than the mean blood pressure. However, the predetermined pressure is assumed to be a small value.

[0139] <Modification 3> FIG. 16 is a flowchart showing Modification 3 of the blood pressure measurement process (depressurization measurement method) in the arrhythmia determination mode.

[0140] 16, the processes in steps S132 to S144, S146, and S150 to S162 are similar to the corresponding processes in FIG. 11, and therefore detailed description thereof will not be repeated.

[0141] After the process of step S144, the processor 110 estimates the mean blood pressure based on the estimated systolic blood pressure and the estimated diastolic blood pressure calculated in step S138 (step S240). Specifically, the processor 110 calculates the estimated mean blood pressure based on the estimated systolic blood pressure and the estimated diastolic blood pressure.

[0142] After processing step S146, processor 110 determines whether the cuff pressure during decompression has reached the estimated mean blood pressure calculated in step S240 (step S250). If the cuff pressure has not reached the estimated mean blood pressure (NO in step S250), processor 110 executes step S146. If the cuff pressure has reached the estimated mean blood pressure (YES in step S250), processor 110 changes the decompression speed from speed Vf to speed Vg (e.g., 4 mmHg / s) (step S150).

[0143] 16, the speed change period (i.e., period Tg) during which the cuff pressure is increased at the speed Vg is the period from the time when it is determined that the cuff pressure has reached the estimated mean blood pressure until a specified time has elapsed. In the above-mentioned step S250, the processor 110 may determine whether the cuff pressure has reached a blood pressure that is a predetermined pressure lower (or a predetermined pressure higher) than the estimated mean blood pressure. However, the predetermined pressure is assumed to be a small value.

[0144] <Modification 4> FIG. 17 is a flowchart showing Modification 4 of the blood pressure measurement process (depressurization measurement method) in the arrhythmia determination mode.

[0145] 17, the processes in steps S132 to S136, S138 to S146, and S150 to S162 are similar to the corresponding processes in FIG. 11, and therefore detailed description thereof will not be repeated.

[0146] After the process of step S136, processor 110 determines whether or not the pulse wave amplitude has reached a maximum during the pressurization process (step S270). If the pulse wave amplitude has not reached a maximum (NO in step S270), processor 110 continues to pressurize the cuff by executing the process of step S136. If the pulse wave amplitude has reached a maximum (YES in step S270), processor 110 identifies the cuff pressure corresponding to the maximum pulse wave amplitude (i.e., the cuff pressure at the timing when the pulse wave amplitude reached a maximum) (step S280) and executes the process of step S138.

[0147] After processing step S146, processor 110 determines whether the cuff pressure during decompression has reached the cuff pressure specified in step S280 (hereinafter also referred to as the "specific cuff pressure") (step S290). If the cuff pressure has not reached the specific cuff pressure (NO in step S290), processor 110 executes step S146. If the cuff pressure has reached the specific cuff pressure (YES in step S290), processor 110 changes the decompression speed from speed Vf to speed Vg (for example, 4 mmHg / s) (step S150).

[0148] 17, the speed change period (i.e., period Tg) during which the cuff pressure is increased at the speed Vg is a period from the time when it is determined that the cuff pressure has reached the specific cuff pressure until a specified time has elapsed. Note that in the above-mentioned step S290, the processor 110 may determine whether the cuff pressure has reached a pressure that is a predetermined pressure lower (or higher) than the specific cuff pressure. However, the predetermined pressure is assumed to be a small value.

[0149] <Other embodiments> (1) In the above embodiment, the inflation speed is slowed down during the period Tb, and the depressurization speed is slowed down during the period Tg. However, the present invention is not limited to this configuration. For example, the inflation of the cuff pressure may be stopped during the period Tb (i.e., the inflation speed is set to zero) and the depressurization of the cuff pressure may be stopped during the period Tg (i.e., the depressurization speed is set to zero).

[0150] Fig. 18 is a diagram showing the correspondence relationship between the pulse wave signal and the cuff pressure during blood pressure measurement (inflation measurement method) in the arrhythmia determination mode according to another embodiment. Referring to Fig. 18, in a period Tb, the inflation of the cuff pressure is stopped and the cuff pressure is maintained. The inflation speed Vb in the period Tb is zero.

[0151] Fig. 19 is a diagram showing the correspondence relationship between the pulse wave signal and the cuff pressure during blood pressure measurement (depressurization measurement method) in the arrhythmia determination mode according to another embodiment. Referring to Fig. 19, in a period Tg, the reduction in the cuff pressure is stopped and the cuff pressure is maintained. The depressurization speed Vg in the period Tg is zero.

[0152] Fig. 20 is a flowchart showing a blood pressure measurement process (pressurization measurement method) in an arrhythmia determination mode according to another embodiment. The flowchart in Fig. 20 corresponds to a case in which steps S110 and S114 in Fig. 9 are replaced with steps S300 and S310, respectively.

[0153] 20, the processes in steps S102 to S108, S112, and S116 to S124 are similar to the corresponding processes in FIG. 9, and therefore detailed description thereof will not be repeated.

[0154] When the pulse wave amplitude becomes maximum (YES in step S108), the processor 110 stops the pump 32 (step S300), which stops the application of cuff pressure and maintains the cuff pressure.

[0155] The processor 110 determines whether or not a specified time has elapsed since the pump 32 was stopped (maintenance of the cuff pressure was started) (step S112). If the specified time has not elapsed (NO in step S112), the processor 110 executes step S112. If the specified time has elapsed (YES in step S112), the processor 110 drives the pump 32 to start inflating the cuff 20 at a speed Va (step S310) and executes step S116.

[0156] Similarly, steps S110 and S114 in FIG. 12 and FIG. 14 may be replaced with steps S300 and S310, respectively.

[0157] Fig. 21 is a flowchart showing a blood pressure measurement process (depressurization measurement method) in an arrhythmia determination mode according to another embodiment. The flowchart in Fig. 21 corresponds to a case in which steps S150 and S154 in Fig. 11 are replaced with steps S320 and S330, respectively.

[0158] 21, the processes in steps S132 to S148, S152, and S156 to S162 are similar to the corresponding processes in FIG. 11, and therefore detailed description thereof will not be repeated.

[0159] When the pulse wave amplitude becomes maximum (YES in step S148), the processor 110 closes the valve 33 (step S320). This stops the reduction in the cuff pressure, and the cuff pressure is maintained. The processor 110 determines whether or not a specified time has elapsed since the valve 33 was closed (maintenance of the cuff pressure started) (step S152). If the specified time has not elapsed (NO in step S152), the processor 110 executes step S152. If the specified time has elapsed (YES in step S152), the processor 110 controls the valve 33 to be gradually opened at a speed Vf (step S330), and executes step S156.

[0160] Similarly, steps S150 and S154 in FIGS. 13, 15, 16 and 17 may be replaced with steps S320 and S330, respectively.

[0161] (2) In the above-described embodiment, a program for causing a computer to function and execute the control as described in the above-described flowchart can also be provided. Such a program can be provided as a program product by being recorded on a non-transitory computer-readable recording medium such as a flexible disk, a CD-ROM (Compact Disk Read Only Memory), a secondary storage device, a main storage device, or a memory card that is attached to the computer. Alternatively, the program can be provided by being recorded on a recording medium such as a hard disk built into the computer. The program can also be provided by downloading via a network.

[0162] (3) The configurations exemplified as the above-mentioned embodiments are merely examples of the configurations of the present invention, and may be combined with other known technologies, or may be modified, such as by omitting some parts, without departing from the scope of the present invention. In addition, the above-mentioned embodiments may be implemented by appropriately adopting the processes and configurations described in other embodiments.

[0163] [Note] As described above, the present embodiment includes the following disclosure.

[0164] [Configuration 1] A blood pressure monitor (100) comprising: a blood pressure measurement unit (220) that measures the blood pressure of a user based on a pulse wave signal during a pressurization process in which a cuff pressure indicating an internal pressure of a cuff (20) attached to a measurement site of the user is pressurized, the blood pressure measurement unit (220) sets an inflation speed during a predetermined period of the pressurization process slower than an inflation speed during any other period of the pressurization process other than the predetermined period, the predetermined period being set based on a timing when an amplitude of the pulse wave signal becomes maximum during the pressurization process or a timing when the cuff pressure becomes a mean blood pressure of the user during the pressurization process, and further comprising a determination unit (230) that determines arrhythmia of the user based on the pulse wave signal during the pressurization process.

[0165] [Configuration 2] The blood pressure monitor (100) according to configuration 1, wherein the blood pressure measurement unit (220) sets the predetermined period to a period from when the amplitude of the pulse wave signal becomes maximum during the pressurization process until a specified time has elapsed.

[0166] [Configuration 3] The blood pressure monitor (100) according to configuration 1, further comprising a memory unit (250) that stores associated information associating the cuff pressure and the pulse wave signal obtained during a previous blood pressure measurement of the user, wherein the blood pressure measurement unit (220) extracts the cuff pressure at a timing when the amplitude of the pulse wave signal during the pressurization process during the previous blood pressure measurement of the user is maximum based on the associated information, and sets the predetermined period to a period from a timing when the cuff pressure during the pressurization process during a current blood pressure measurement of the user reaches the extracted cuff pressure until a specified time has elapsed.

[0167] [Configuration 4] The blood pressure monitor (100) according to configuration 1, further comprising a memory unit (250) that stores the systolic blood pressure and diastolic blood pressure of the user obtained during a previous blood pressure measurement of the user, wherein the blood pressure measurement unit (220) calculates the mean blood pressure based on the systolic blood pressure and the diastolic blood pressure, and sets the predetermined period to a period from when the cuff pressure in the pressurization process during a current blood pressure measurement of the user reaches the mean blood pressure until a specified time has elapsed.

[0168] [Configuration 5] The blood pressure monitor (100) according to any one of configurations 1 to 4, wherein the blood pressure measurement section (220) sets the inflation speed during the predetermined period to zero.

[0169] [Configuration 6] A blood pressure monitor (100) comprising: a blood pressure measurement unit (220) that measures the blood pressure of the user based on a pulse wave signal during a depressurization process in which a cuff pressure, which indicates an internal pressure of a cuff (20) attached to a measurement site of a user, is increased to a pressure greater than a specified pressure, and then the cuff pressure is decreased, the blood pressure measurement unit (220) sets a depressurization rate during a predetermined period of the depressurization process slower than a depressurization rate during any other period of the depressurization process other than the predetermined period, the predetermined period being set based on a timing when an amplitude of the pulse wave signal becomes maximum during the depressurization process or a timing when the cuff pressure becomes a mean blood pressure of the user during the depressurization process, and a determination unit (230) that determines arrhythmia of the user based on the pulse wave signal during the depressurization process.

[0170] [Configuration 7] 7. The blood pressure monitor according to claim 6, wherein the blood pressure measurement unit sets, as the predetermined period, a period from when the amplitude of the pulse wave signal becomes maximum during the depressurization process until a specified time has elapsed.

[0171] [Configuration 8] The blood pressure monitor (100) according to configuration 6, further comprising a memory unit (250) for storing associated information associating the cuff pressure and the pulse wave signal obtained during a previous blood pressure measurement of the user, wherein the blood pressure measurement unit (220) extracts the cuff pressure at a timing when the amplitude of the pulse wave signal during the decompression process during the previous blood pressure measurement of the user is maximum based on the associated information, and sets the predetermined period to a period from a timing when the cuff pressure during the decompression process during a current blood pressure measurement of the user reaches the extracted cuff pressure until a specified time has elapsed.

[0172] [Configuration 9] The blood pressure monitor (100) according to configuration 6, further comprising a memory unit (250) that stores the systolic blood pressure and the diastolic blood pressure of the user obtained during a previous blood pressure measurement of the user, wherein the blood pressure measurement unit (220) calculates the mean blood pressure based on the systolic blood pressure and the diastolic blood pressure, and sets the predetermined period to a period from when the cuff pressure reaches the mean blood pressure during the depressurization process during a current blood pressure measurement of the user until a specified time has elapsed.

[0173] [Configuration 10] The blood pressure monitor (100) according to configuration 6, wherein the blood pressure measurement unit (220) estimates the systolic blood pressure and diastolic blood pressure of the user during the pressurization process, estimates the mean blood pressure based on the estimated systolic blood pressure and diastolic blood pressure, and sets the predetermined period as a period from the time when the cuff pressure during the depressurization process reaches the mean blood pressure to after a specified time has elapsed.

[0174] [Configuration 11] The blood pressure monitor (100) according to configuration 6, wherein the blood pressure measurement unit (220) identifies a cuff pressure at a timing when an amplitude of a pulse wave signal becomes maximum during the pressurization process, and sets a period from a timing when the cuff pressure during the depressurization process reaches the identified cuff pressure until a specified time has elapsed as the predetermined period.

[0175] [Configuration 12] 12. The sphygmomanometer (100) according to any one of configurations 6 to 11, wherein the blood pressure measurement section (220) sets the depressurization rate during the predetermined period to zero.

[0176] [Configuration 13] a step of measuring the blood pressure of the user based on a pulse wave signal during a pressurization process in which a cuff pressure indicating an internal pressure of a cuff (20) attached to a measurement site of the user is applied, the measuring step including making an inflation speed during a predetermined period of the pressurization process slower than an inflation speed during any other period of the pressurization process other than the predetermined period, the predetermined period being set based on a timing when an amplitude of the pulse wave signal becomes maximum during the pressurization process or a timing when the cuff pressure becomes a mean blood pressure of the user during the pressurization process, and further including a step of determining arrhythmia of the user based on the pulse wave signal during the pressurization process.

[0177] [Configuration 14] a step of measuring the user's blood pressure based on a pulse wave signal during a depressurization process in which a cuff pressure indicating an internal pressure of a cuff (20) attached to a measurement site of a user is increased to a pressure greater than a specified pressure, after which the cuff pressure is decreased, the measuring step including making a depressurization rate during a predetermined period of the depressurization process slower than a depressurization rate during any other period of the depressurization process other than the predetermined period, the predetermined period being set based on a timing during the depressurization process when an amplitude of the pulse wave signal becomes maximum or a timing during the depressurization process when the cuff pressure becomes a mean blood pressure of the user, and further including a determination unit for determining arrhythmia of the user based on the pulse wave signal during the depressurization process.

[0178] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the scope and meaning equivalent to the claims. [Explanation of symbols]

[0179] 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 memory unit, 310 conversion circuit, 320 pump drive circuit, 330 valve drive circuit.

Claims

1. A blood pressure measuring device includes a blood pressure measurement unit that measures the blood pressure of a user based on a pulse wave signal in a pressurization process of pressurizing a cuff pressure indicating the internal pressure of a cuff attached to a measurement site of the user, wherein the blood pressure measurement unit makes a pressurization speed in a predetermined period of the pressurization process slower than a pressurization speed in another period other than the predetermined period in the pressurization process, and the predetermined period is set based on a timing at which an amplitude of the pulse wave signal becomes maximum in the pressurization process or a timing at which the cuff pressure becomes the average blood pressure of the user in the pressurization process, and further includes a determination unit that determines an arrhythmia of the user based on the pulse wave signal in the pressurization process.

2. The blood pressure measuring device according to claim 1, wherein the blood pressure measurement unit sets a period from a timing at which an amplitude of the pulse wave signal becomes maximum in the pressurization process to after a lapse of a specified time as the predetermined period.

3. The blood pressure measuring device further includes a storage unit that stores association information associating the cuff pressure and the pulse wave signal obtained when measuring the blood pressure of the user in the past, and the blood pressure measurement unit extracts the cuff pressure at a timing at which an amplitude of the pulse wave signal becomes maximum in the pressurization process when measuring the blood pressure of the user in the past based on the association information, and sets a period from a timing at which the cuff pressure in the pressurization process when measuring the blood pressure of the user this time reaches the extracted cuff pressure to after a lapse of a specified time as the predetermined period.

4. The blood pressure measuring device further includes a storage unit that stores the systolic blood pressure and the diastolic blood pressure of the user obtained when measuring the blood pressure of the user in the past, and the blood pressure measurement unit calculates the average blood pressure based on the systolic blood pressure and the diastolic blood pressure, and sets a period from a timing at which the cuff pressure in the pressurization process when measuring the blood pressure of the user this time reaches the average blood pressure to after a lapse of a specified time as the predetermined period.

5. The blood pressure measuring device according to any one of claims 1 to 4, wherein the blood pressure measurement unit sets the pressurization speed in the predetermined period to zero.

6. A blood pressure measuring device includes a blood pressure measurement unit that measures the blood pressure of a user based on a pulse wave signal in a decompression process of decompressing a cuff pressure indicating the internal pressure of a cuff attached to a measurement site of the user after a pressurization process of pressurizing the cuff pressure to a pressure higher than a specified pressure. The blood pressure measurement unit makes the decompression speed during a predetermined period of the decompression process slower than the decompression speed during other periods other than the predetermined period in the decompression process. The predetermined period is set based on the timing when the amplitude of the pulse wave signal is maximum in the decompression process or the timing when the cuff pressure becomes the average blood pressure of the user in the decompression process. A sphygmomanometer further comprising a determination unit that determines an arrhythmia of the user based on a pulse wave signal in the decompression process.

7. The sphygmomanometer according to claim 6, wherein the blood pressure measurement unit sets a period from the timing when the amplitude of the pulse wave signal is maximum in the decompression process until a predetermined time has elapsed as the predetermined period.

8. The sphygmomanometer further comprises a storage unit that stores association information associating the cuff pressure and the pulse wave signal obtained when measuring the blood pressure of the user in the past, The blood pressure measurement unit, extracts the cuff pressure at the timing when the amplitude of the pulse wave signal is maximum in the decompression process when measuring the blood pressure of the user in the past based on the association information, The sphygmomanometer according to claim 6, wherein a period from the timing when the cuff pressure in the decompression process at the time of measuring the blood pressure of the user this time reaches the extracted cuff pressure until a predetermined time has elapsed is set as the predetermined period.

9. The sphygmomanometer further comprises a storage unit that stores the systolic blood pressure and the diastolic blood pressure of the user obtained when measuring the blood pressure of the user in the past, The blood pressure measurement unit, calculates the average blood pressure based on the systolic blood pressure and the diastolic blood pressure, The sphygmomanometer according to claim 6, wherein a period from the timing when the cuff pressure in the decompression process at the time of measuring the blood pressure of the user this time reaches the average blood pressure until a predetermined time has elapsed is set as the predetermined period.

10. The blood pressure measurement unit, estimates the systolic blood pressure and the diastolic blood pressure of the user in the pressurization process, and estimates the average blood pressure based on the estimated systolic blood pressure and the diastolic blood pressure, The sphygmomanometer according to claim 6, wherein a period from the timing when the cuff pressure in the decompression process reaches the average blood pressure until a predetermined time has elapsed is set as the predetermined period.

11. The blood pressure measurement unit, identifies the cuff pressure at the timing when the amplitude of the pulse wave signal is maximum in the pressurization process. The sphygmomanometer according to claim 6, wherein a period from a timing when the cuff pressure in the decompression process reaches the specified cuff pressure to after a lapse of a specified time is set as the predetermined period.

12. The sphygmomanometer according to any one of claims 6 to 11, wherein the blood pressure measurement unit sets a decompression rate in the predetermined period to zero.

13. including a step of measuring the blood pressure of the user based on a pulse wave signal in a pressurization process of pressurizing a cuff pressure indicating an internal pressure of a cuff attached to a measurement site of the user; the step of measuring includes making a pressurization rate in a predetermined period of the pressurization process slower than a pressurization rate in another period other than the predetermined period in the pressurization process; the predetermined period is set based on a timing when an amplitude of the pulse wave signal becomes maximum in the pressurization process or a timing when the cuff pressure becomes the average blood pressure of the user in the pressurization process; A blood pressure measurement method further including a step of determining an arrhythmia of the user based on a pulse wave signal in the pressurization process.

14. including a step of measuring the blood pressure of the user based on a pulse wave signal in a decompression process of decompressing the cuff pressure after a pressurization process of pressurizing the cuff pressure indicating the internal pressure of the cuff attached to the measurement site of the user to a pressure higher than a specified pressure; the step of measuring includes making a decompression rate in a predetermined period of the decompression process slower than a decompression rate in another period other than the predetermined period in the decompression process; the predetermined period is set based on a timing when an amplitude of the pulse wave signal becomes maximum in the decompression process or a timing when the cuff pressure becomes the average blood pressure of the user in the decompression process; A blood pressure measurement method further including a step of determining an arrhythmia of the user based on a pulse wave signal in the decompression process.

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