Blood pressure measurement device and blood pressure measurement system

Abstract

A blood pressure measuring device characterized by comprising: a feature quantity acquisition section that acquires one or more feature quantities related to estimation of a blood pressure value of a human body; a blood pressure value calculation section that calculates an estimated blood pressure value based on the feature quantities; a measured blood pressure value acquisition section that acquires a measured blood pressure value measured by a method different from the calculation performed by the blood pressure value calculation section; a calibration determination section that determines whether the feature quantities acquired by the feature quantity acquisition section deviate from a prescribed reference value, and decides to acquire the measured blood pressure value in the case of determination of deviation; and a calibration processing section that calibrates a calculation algorithm of the estimated blood pressure value performed by the blood pressure value calculation section using the measured blood pressure value, the calibration processing section performing change of the reference value based on the measured blood pressure value acquired by the decision of the calibration determination section and the estimated blood pressure value calculated using the feature quantities deviating from the reference value.

Description

Technical Field

[0001] This invention relates to a blood pressure measuring device and a blood pressure measuring system. Background Technology

[0002] Conventionally, methods for measuring human blood pressure include calculating an estimated blood pressure value based on a non-invasively obtainable characteristic quantity, and then measuring the blood pressure using this estimated value. Specifically, for example, it is known that there is a correlation between blood pressure and pulse wave transit time (PTT), which is the time required for a pulse wave to travel between two points on an artery, and a device for non-invasive continuous blood pressure measurement based on this correlation has been proposed (e.g., Patent Document 1).

[0003] Patent Document 1 discloses a blood pressure measuring device. This device has electrodes serving as an ECG (Electrocardiogram) sensor and a PPG (Photoplethysmograph) sensor, among other pulse wave sensors, mounted on a band wrapped around the user's measurement area. It calculates the time difference (PTT) between characteristic points of the ECG waveform and those of the pulse wave signal, thereby measuring blood pressure. This configuration, where the electrodes and pulse wave sensor are integrated into the band, allows the user to wear the device simply by wrapping the band around them. Therefore, according to the technology described in Patent Document 1, a blood pressure measuring device can be provided that is easy for the user to wear and significantly reduces the user's burden during routine, non-invasive, continuous blood pressure measurements.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2019-154864 Summary of the Invention

[0007] The problem the invention aims to solve

[0008] Furthermore, as described in Patent Document 1, when blood pressure measurement (estimation) is performed based on the correlation with a characteristic quantity that can be non-invasively acquired, the correlation varies depending on the user and the circumstances of the blood pressure measurement. Therefore, it is required to measure accurate blood pressure values ​​at appropriate timing and frequency, and to calibrate the algorithm used for blood pressure estimation based on this. Patent Document 1 also describes a method for determining whether conditions are met for recommending blood pressure measurement of the user for calibration, and outputting information indicating blood pressure measurement if the conditions are met.

[0009] As mentioned above, when obtaining accurate blood pressure values ​​for calibration, oscillometric and Korotkoff sound methods are considered. However, the pressure exerted by the cuff at the measurement site is uncomfortable for the average user. Therefore, when blood pressure measurements are taken continuously, frequent calibration measurements become a burden for the user. On the other hand, when performing blood pressure measurements (estimates) based on characteristic quantities, in order to calculate reliable and highly accurate measured values ​​(estimated values), appropriate calibration is required based on various usage conditions such as the user's activity level, ambient temperature, and nutritional status during continuous measurement. Ideally, when calibrating a blood pressure calculation algorithm that is compatible with the user, calibration should be performed at a frequency necessary for accurate blood pressure value estimation, while minimizing the burden on the user.

[0010] However, in real-world usage environments, users intentionally experiment with various measurement conditions (exercise intensity, ambient temperature, nutritional status, etc.), making it difficult to calibrate blood pressure under multiple conditions. Furthermore, if the blood pressure calculation algorithm is uniformly calibrated based on pre-defined threshold values ​​of characteristic quantities, as in previous technologies, the frequency of calibration will remain constant even if the blood pressure estimation accuracy is low (or conversely, even if it reaches sufficient accuracy). Therefore, it is impossible to reduce the number of calibrations to avoid unnecessary blood pressure measurements or increase the number of calibrations to achieve higher accuracy in calculating the estimated blood pressure value, based on individual user characteristics and measurement conditions. In other words, there is a problem of not being able to perform calibration at an appropriate frequency.

[0011] In view of the above, the object of the present invention is to provide a technique that optimizes the frequency of blood pressure calculation algorithm calibration based on the user when using feature quantities related to the estimation of blood pressure values ​​to estimate human blood pressure.

[0012] Technical solution

[0013] A blood pressure measuring device, characterized in that the blood pressure measuring device comprises:

[0014] The feature acquisition unit acquires one or more features that are related to the estimation of human blood pressure values.

[0015] The blood pressure calculation unit calculates the estimated blood pressure value based on the aforementioned characteristic quantity;

[0016] The measured blood pressure value acquisition unit acquires the measured blood pressure value by a method different from the calculation performed by the blood pressure value calculation unit;

[0017] The calibration determination unit determines whether the feature value acquired by the feature acquisition unit deviates from a predetermined reference value, and if it determines that the feature value deviates, it decides to acquire the measured blood pressure value; and

[0018] The calibration processing unit uses the measured blood pressure value to calibrate the algorithm for calculating the estimated blood pressure value implemented by the blood pressure value calculation unit.

[0019] The calibration processing unit changes the reference value based on the measured blood pressure value obtained by the calibration determination unit and the estimated blood pressure value calculated using the characteristic quantity that deviates from the reference value.

[0020] It should be noted that the features mentioned here include, but are not limited to, waveform-related data such as the height of inflection points, the slope between inflection points, and the area of ​​specified parts of the waveform obtained from electrocardiogram (ECG) and pulse wave waveforms; features calculated from multiple waveform data such as PTT and Pulse Arrival Time (PAT); and other biological information related to heartbeat, such as PTT and PAT. For example, it also includes information related to the patient's personal attributes, such as height, age, weight, and medication history, as well as environmental information such as season and temperature. Furthermore, "calculating estimated blood pressure values ​​based on features" not only refers to calculating an estimated value based on a single feature, but also includes calculating estimated blood pressure values ​​by combining multiple features.

[0021] In this way, if the reference value used to determine whether calibration is needed is changed based on the measured blood pressure value and the estimated blood pressure value, the blood pressure calculation algorithm can be calibrated repeatedly according to the different characteristics of each user to improve the accuracy of blood pressure estimation, and the frequency of blood pressure calculation algorithm calibration can be optimized.

[0022] Alternatively, if the difference between the measured blood pressure value obtained by the calibration determination unit and the estimated blood pressure value calculated using the feature quantity deviating from the reference value is below a predetermined threshold, the calibration processing unit may change the reference value to a value that reduces the frequency of obtaining the measured blood pressure value. Alternatively, if the difference between the measured blood pressure value obtained by the calibration determination unit and the estimated blood pressure value calculated using the feature quantity deviating from the reference value is greater than a predetermined threshold, the calibration processing unit may change the reference value to a value that increases the frequency of obtaining the measured blood pressure value.

[0023] When performing blood pressure measurements for calibration, the greater the difference between the estimated and measured blood pressure values, the less appropriate the blood pressure estimation algorithm becomes. Therefore, as described above, if the difference between the estimated and measured blood pressure values ​​is large, the reference value of the characteristic quantity can be changed to increase the frequency of calibration (e.g., by decreasing the value if an upper limit threshold is set). On the other hand, if the difference between the estimated and measured blood pressure values ​​is small, and the accuracy of the blood pressure estimation is sufficiently high, the frequency of calibration can be reduced (e.g., by increasing the value if an upper limit threshold is set) to lessen the burden on the user. In this way, the number of calibration operations can be easily optimized without complex processing.

[0024] Alternatively, the blood pressure measuring device may also have an output unit that outputs information indicating the need to obtain the measured blood pressure value when the calibration determination unit decides to acquire the measured blood pressure value. It should be noted that the output unit mentioned here can be, for example, an LCD display, but it can also be other display units besides a display unit, such as an LED light, a speaker, or a vibration mechanism. With this configuration, the user can easily identify when a measured blood pressure value needs to be obtained.

[0025] Alternatively, the blood pressure measuring device may also include a blood pressure measuring unit for measuring the measured blood pressure value. When the calibration determination unit decides to acquire the measured blood pressure value, the measured blood pressure value acquisition unit acquires the measured blood pressure value by measuring the measured blood pressure value performed by the blood pressure measuring unit. In this way, the blood pressure measuring unit is also included, thereby allowing the measured blood pressure value to be easily acquired by measuring the blood pressure value when the need arises. This reduces the burden of using other measuring devices for blood pressure measurement and the burden of data input.

[0026] Alternatively, the blood pressure measuring device may also include a blood pressure measuring unit and an operation input unit for measuring the measured blood pressure value. When the measured blood pressure value acquisition unit receives an input indicating the measurement of the measured blood pressure value via the operation input unit, it acquires the measured blood pressure value by measuring the measured blood pressure value implemented by the blood pressure measuring unit.

[0027] Therefore, blood pressure values ​​are measured by the blood pressure measurement unit through user operation, allowing users to perform blood pressure measurements after making adequate preparations. This prevents blood pressure measurements from being taken at unexpected or inappropriate times.

[0028] Furthermore, the present invention can also be considered as a blood pressure measurement system having the following configuration:

[0029] A blood pressure measurement system, characterized in that the blood pressure measurement system has:

[0030] The feature acquisition unit acquires one or more features that are related to the estimation of human blood pressure values.

[0031] The blood pressure calculation unit calculates the estimated blood pressure value based on the aforementioned characteristic quantity;

[0032] The measured blood pressure value acquisition unit acquires the measured blood pressure value by a method different from the calculation performed by the blood pressure value calculation unit;

[0033] The calibration determination unit determines whether the feature quantity acquired by the feature quantity acquisition unit deviates from the specified reference value, and if it determines that it has deviated, it decides to acquire the measured blood pressure value; and

[0034] The calibration processing unit uses the measured blood pressure value to calibrate the calculation algorithm for the estimated blood pressure value implemented by the blood pressure value calculation unit.

[0035] The calibration processing unit changes the reference value based on the measured blood pressure value obtained through the decision of the calibration determination unit and the estimated blood pressure value calculated using the characteristic quantity that deviates from the reference value.

[0036] With this configuration, the individual units do not function as a single unit, but rather as a whole system providing problem-solving capabilities. Therefore, it is possible to reduce the user's burden through flexible methods such as selecting the functions of the devices the user possesses and uses.

[0037] Alternatively, the blood pressure measurement system may be configured to include:

[0038] The measuring device includes at least one sensor for detecting the aforementioned characteristic quantity; and

[0039] The information processing device includes at least the calibration processing unit.

[0040] With such a configuration, the complex computational processing unit can be used as a separate terminal dedicated to information processing. By communicating with servers located far from the measurement equipment used by the user, a cloud system can be built that can calibrate the algorithms of each user's measurement equipment.

[0041] Alternatively, the measuring device may also include a blood pressure measuring unit for determining the measured blood pressure value. Furthermore, the measuring device may also be a wearable device that can be worn on the body at all times. This invention is suitable for using a system configured in this way to perform non-invasive, continuous blood pressure measurements routinely.

[0042] It should be noted that as long as the above-mentioned components and processes do not create technical contradictions, they can be combined with each other to constitute the present invention.

[0043] Invention Effects

[0044] According to the present invention, a technique is provided that optimizes the frequency of blood pressure calculation algorithm calibration based on the user when using a characteristic quantity estimated by blood pressure value to estimate blood pressure in a human body. Attached Figure Description

[0045] Figure 1 This is a schematic diagram showing the blood pressure measuring device according to Embodiment 1 of the present invention.

[0046] Figure 2 The first figure illustrates the appearance of the blood pressure measuring device according to Embodiment 1.

[0047] Figure 3 The second figure illustrates the appearance of the blood pressure measuring device according to Embodiment 1.

[0048] Figure 4 This is a cross-sectional view of the blood pressure measuring device according to Embodiment 1.

[0049] Figure 5 This is a block diagram illustrating the hardware configuration of the control system of the blood pressure measuring device according to Embodiment 1.

[0050] Figure 6 This is a block diagram illustrating the software configuration of the blood pressure measuring device according to Embodiment 1.

[0051] Figure 7 This is a flowchart illustrating an example of the processing flow of the blood pressure measuring device based on Embodiment 1.

[0052] Figure 8 This is a schematic diagram showing the blood pressure measurement system according to Embodiment 2 of the present invention.

[0053] Figure 9 This is a schematic block diagram showing the functional configuration of each element of the blood pressure measurement system in Embodiment 2.

[0054] Figure 10 This is a schematic diagram showing the blood pressure measurement system according to Embodiment 3 of the present invention.

[0055] Figure 11 This is a schematic block diagram showing the functional configuration of each element of the blood pressure measurement system in Embodiment 3. Detailed Implementation

[0056] <Implementation Method 1>

[0057] Hereinafter, specific embodiments of the present invention will be described based on the accompanying drawings. However, unless otherwise specified, the dimensions, materials, shapes, relative configurations, etc. of the components described in the following embodiments are not intended to limit the scope of the present invention.

[0058] (summary)

[0059] Figure 1 This is a schematic diagram illustrating one embodiment of a blood pressure measuring device 10. The blood pressure measuring device 10 is a wearable device worn on the upper arm, the part of the body being measured by the user. The blood pressure measuring device 10 is generally configured to include a strap 120, a first blood pressure measuring unit 130, a second blood pressure measuring unit 140, a calibration determination unit 150, an indicator unit 160, and a calibration processing unit 170.

[0060] The band 120 includes a band 121 and a main body 122. The band 121 refers to a band-like component that is wrapped around and worn on the upper arm, and is sometimes also referred to by other names such as a strap or cuff. The band 121 has an inner circumferential surface and an outer circumferential surface. The inner circumferential surface is the surface that contacts the user's upper arm when the user is wearing the blood pressure measuring device 10 (hereinafter referred to as the "wearing state"), and the outer circumferential surface is the surface opposite to the inner circumferential surface.

[0061] The main body 122 is assembled onto the belt 121. The main body 122 houses the operation unit 1221 and the display unit 1222, and also houses the control unit 1501 (described later). Figure 5 (As shown in the diagram) and other components. The operation unit 1221 is an input device that allows the user to input instructions for the blood pressure measuring device 10. Figure 1 In the example, the operation unit 1221 includes multiple push-buttons. The display unit 1222 is a display device that displays information such as messages urging the execution of blood pressure measurement and blood pressure measurement results. As the display device, for example, a liquid crystal display (LCD) or an OLED (Organic Light Emitting Diode) display can be used. A touchscreen that serves as both a display device and an input device can also be used. A sound-emitting element such as a speaker or piezoelectric speaker can also be provided in the main body 122. Furthermore, a microphone can be provided in the main body 122 so that the user can input instructions via voice.

[0062] The first blood pressure measuring unit 130 non-invasively measures the user's pulse wave travel time (PTT) and calculates the blood pressure value based on the measured PTT. Hereinafter, the blood pressure value calculated based on the PTT in this manner will also be referred to as the estimated blood pressure value. The first blood pressure measuring unit 130 is capable of continuous blood pressure measurement, obtaining the blood pressure value for each heartbeat.

[0063] The second blood pressure measuring unit 140 measures blood pressure in a different manner than the first blood pressure measuring unit 130. Specifically, the second blood pressure measuring unit 140 measures blood pressure at specific timings, such as in response to user actions, using methods like oscillometrics or Korotkoff sounds. While the second blood pressure measuring unit 140 cannot perform continuous blood pressure measurements, it can measure blood pressure more accurately than the first blood pressure measuring unit 130. Hereinafter, the blood pressure value measured by the second blood pressure measuring unit 140 will be referred to as the measured blood pressure value.

[0064] The first blood pressure measuring unit 130 includes functional modules such as an electrocardiogram acquisition unit 131, a pulse wave signal acquisition unit 132, a pulse wave propagation time calculation unit 133, and a blood pressure value calculation unit 134.

[0065] The electrocardiogram (ECG) acquisition unit 131 has multiple electrodes used to acquire a user's electrocardiogram (ECG). An ECG represents the electrical activity of the heart. The electrodes are disposed on the strap portion 120. For example, the electrodes are positioned on the inner circumferential surface of the strap 121, thereby bringing them into contact with the user's upper arm skin when worn.

[0066] The pulse wave signal acquisition unit 132 includes a pulse wave sensor, which is used to acquire a pulse wave signal representing the user's pulse wave. The pulse wave sensor is disposed on the band 120. For example, the pulse wave sensor is disposed on the inner circumferential surface of the band 121, thereby making the pulse wave sensor in contact with the user's upper arm skin when worn. It should be noted that in some types of pulse wave sensors, such as the radio wave-based pulse wave sensor described later, it is not necessary for the pulse wave sensor to be in contact with the user's upper arm skin when worn.

[0067] The pulse wave propagation time calculation unit 133 calculates the pulse wave propagation time based on the time difference between the waveform feature points of the electrocardiogram acquired by the electrocardiogram acquisition unit 131 and the waveform feature points of the pulse wave signal acquired by the pulse wave signal acquisition unit 132. For example, the pulse wave propagation time calculation unit 133 calculates the time difference between the waveform feature points of the electrocardiogram and the waveform feature points of the pulse wave signal, and outputs the calculated time difference as the pulse wave propagation time. In this embodiment, the pulse wave propagation time is equivalent to the time required for the pulse wave to propagate from the heart to the upper arm (specifically, the location where the pulse wave sensor is positioned) in the artery.

[0068] The blood pressure calculation unit 134 calculates the blood pressure value based on the pulse wave propagation time calculated by the pulse wave propagation time calculation unit 133 and the blood pressure calculation formula. The blood pressure calculation formula is a relational expression representing the relationship between pulse wave propagation time and blood pressure. An example of the blood pressure calculation formula is shown below.

[0069] SBP = A1 / PTT 2 +A2……(1)

[0070] Here, SBP represents systolic blood pressure, PTT represents pulse wave propagation time, and A1 and A2 are parameters.

[0071] The pulse wave propagation time calculation unit 133 can calculate the pulse wave propagation time for each heartbeat, therefore, the blood pressure value calculation unit 134 can calculate the blood pressure value for each heartbeat.

[0072] The calibration determination unit 150 monitors a predetermined characteristic quantity (e.g., PTT in this embodiment) obtained by the first blood pressure measuring unit 130 and determines whether the characteristic quantity deviates from a predetermined reference value (e.g., upper or lower threshold). Furthermore, if it is determined that the characteristic quantity deviates from the predetermined reference value, it decides to obtain the user's measured blood pressure value.

[0073] When the calibration determination unit 150 determines to acquire the measured blood pressure value, the instruction unit 160 outputs information instructing the execution of the blood pressure measurement performed by the second blood pressure measuring unit 140. For example, the instruction unit 160 outputs a notification tone (e.g., a melody) through a sound transmitter and displays the message "Please perform blood pressure measurement" on the display unit 1222. When the user presses a designated button in response to the instruction from the instruction unit 160, the blood pressure measurement performed by the second blood pressure measuring unit 140 is executed. The blood pressure measurement performed by the second blood pressure measuring unit 140 will be described later.

[0074] The calibration processing unit 170 calibrates the blood pressure calculation formula (1) described above based on the measured blood pressure value obtained by the second blood pressure measuring unit 140. The correlation between pulse wave propagation time and blood pressure, as expressed by the blood pressure calculation formula, varies from user to user; therefore, the blood pressure calculation formula needs to be calibrated user-specifically. The calibration of the blood pressure calculation formula (specifically, the determination of parameters A1 and A2) is based on the measured blood pressure value obtained by the second blood pressure measuring unit 140. Details regarding the calibration of the blood pressure calculation formula will be described later.

[0075] As described above, in the blood pressure measuring device 10, multiple electrodes for acquiring an electrocardiogram and a pulse wave sensor for acquiring a pulse wave signal are provided together in the strap 120. Therefore, the electrodes and pulse wave sensor can be fitted to the user simply by wrapping the strap 120 around the upper arm. This makes it easy for the user to wear and reduces the user's resistance to wearing the blood pressure measuring device 10.

[0076] Furthermore, the pulse wave propagation time is calculated as the time difference between the waveform feature points of the electrocardiogram and the waveform feature points of the pulse wave signal in the upper arm. The pulse wave propagation time obtained in the blood pressure measuring device 10 is a larger value than the pulse wave propagation time measured between two points in the upper arm. In other words, a longer pulse wave propagation distance is ensured. Therefore, the error generated when calculating the time difference between the waveform feature points of the electrocardiogram and the waveform feature points of the pulse wave signal has a smaller impact on the pulse wave propagation time, and the pulse wave propagation time can be accurately measured. As a result, the reliability of the blood pressure value obtained by blood pressure measurement based on pulse wave propagation time is improved.

[0077] (Example of composition)

[0078] The blood pressure measuring device 10 will be described in more detail below.

[0079] Reference Figures 2 to 6 An example of the configuration of the blood pressure measuring device 10 of this embodiment will be described. Figure 2 and Figure 3 This is a top view illustrating the appearance of the blood pressure measuring device 10. Specifically, Figure 2 The blood pressure measuring device 10 is shown as viewed from the outer peripheral surface 1211 side of the belt 121 with the belt 121 extended. Figure 3 The blood pressure measuring device 10 is shown as viewed from the inner circumferential surface 1212 side of the belt 121 with the belt 121 unfolded. Figure 4 A cross-section of the blood pressure measuring device 10 in its worn state is shown.

[0080] The strap 121 has a mounting component that allows the strap 121 to be detachably attached to the upper arm. Figure 2 and Figure 3 In the example shown, the fitting member is a hook-and-loop fastener having a ring surface 1213 with a plurality of rings and a hook surface 1214 with a plurality of hooks. The ring surface 1213 is disposed on the outer peripheral surface 1211 of the belt 121, i.e., the end 1215A of the belt 121 in the longitudinal direction. The longitudinal direction corresponds to the circumferential direction of the upper arm in the fitting state. The hook surface 1214 is disposed on the inner peripheral surface 1212 of the belt 121, i.e., the end 1215B of the belt 121 in the longitudinal direction. The end 1215B is opposite to the end 1215A in the longitudinal direction of the belt 121. When the ring surface 1213 and the hook surface 1214 are pressed together, the ring surface 1213 and the hook surface 1214 engage. Furthermore, the ring surface 1213 and the hook surface 1214 are separated by pulling them apart.

[0081] like Figure 3 As shown, an electrode assembly 1311 for measuring an electrocardiogram is disposed on the inner circumferential surface 1212 of the band 121. Figure 3In the example, electrode assembly 1311 has six electrodes 1312 arranged in a row at intervals along the longitudinal direction of strip 121. The spacing between electrodes 1312 is, for example, set to one-quarter of the circumference of the upper arm of a user with the thinnest arm. In this configuration, as... Figure 4 As shown, for a user with the slenderest arm, in the worn state, four of the six electrodes 1312 are in contact with the upper arm UA at equal intervals on the circumference of the upper arm, and the remaining two electrodes 1312 are in contact with the outer peripheral surface of the band 121. Figure 4 The image shows the upper arm bone UAB and the upper arm artery UAA. For a user with the assumed largest arm, all six electrodes 1312 are in contact with the upper arm UA when the device is in the wearing state.

[0082] It should be noted that the number of electrodes 1312 is not limited to six; it can also be 2 to 5 or more than 7. When two or three electrodes 1312 are in contact with the upper arm, sometimes an electrocardiogram (ECG) measurement cannot be successfully performed depending on the wearing condition. In cases where an ECG measurement cannot be successfully performed, a message should be displayed on the display unit 1222, requesting the user to re-wear the blood pressure measuring device 10. To avoid situations where an ECG measurement cannot be performed, it is ideal to ensure that at least four electrodes 1312 are in contact with the upper arm when the device is worn.

[0083] When worn, the closer the electrode 1312 is to the heart, the stronger the signal representing the heart's electrical activity obtained using the electrode 1312, i.e., the higher the signal-to-noise ratio (SN ratio). Preferably, as... Figure 3 The electrode 1312 is disposed on the central side portion 1217A of the band 121. The central side portion 1217A is the portion that is closer to the central side (shoulder side) than the center line 1216 when worn. More preferably, the electrode 1312 is disposed on the central side end 1218A of the band 121. The central side end 1218A is the end located on the central side when worn, and the width of the central side end 1218A is, for example, one-third of the total width of the band 121.

[0084] A sensor section 1322 for measuring pulse waves is also disposed on the inner circumferential surface 1212 of the belt 121. Figure 3 In the example, sensor unit 1322 includes a pair of electrodes 1323A and 1323D for energizing the upper arm and a pair of electrodes 1323B and 1323C for detecting voltage. Electrodes 1323A, 1323B, 1323C, and 1323D are arranged in this order along the width direction of band 121. The width direction of band 121 is along the direction of the brachial artery UAA when worn.

[0085] Furthermore, when the sensor unit 1322 is located further away from the heart in the wearing state, the pulse wave travels a longer distance, and the measured pulse wave propagation time is larger. Therefore, the error generated when calculating the time difference between the waveform characteristic points of the electrocardiogram and the waveform characteristic points of the pulse wave signal is smaller compared to the pulse wave propagation time, and the pulse wave propagation time can be accurately measured. Preferably, the sensor unit 1322 is disposed on the distal side portion 1217B of the band 121. The distal side portion 1217B is the portion located on the distal side (elbow side) of the center line 1216 when worn. More preferably, the sensor unit 1322 is disposed on the distal side end portion 1218C of the band 121. The distal side end portion 1218C is the end located on the distal side when worn, and the width of the distal side end portion 1218C is, for example, one-third of the total width of the band 121. The portion between the central side end portion 1218A and the distal side end portion 1218C is called the intermediate portion 1218B.

[0086] like Figure 4 As shown, the band 121 includes an inner fabric 1210A, an outer fabric 1210B, and a compression cuff 1401 disposed between the inner fabric 1210A and the outer fabric 1210B. The compression cuff 1401 is a strip-shaped body that is longer in the longitudinal direction than the band 121 so that it can wrap around the upper arm. For example, the compression cuff 1401 is configured such that two stretchable polyurethane sheets are placed opposite each other in the thickness direction and their peripheral portions are welded together to form a fluid bag. The electrode assembly 1311 and the sensor part 1322 are disposed on the inner fabric 1210A such that they are located between the compression cuff 1401 and the upper arm UA when worn.

[0087] Figure 5 An example of the hardware configuration of the control system of the blood pressure measuring device 10 in this embodiment is shown. Figure 5 In this example, in addition to the operation unit 1221 and display unit 1222 described above, the main body 122 also includes a control unit 1501, a storage unit 1505, a battery 1506, a switching circuit 1313, a subtraction circuit 1314, an analog front-end (AFE) 1315, a pressure sensor 1402, a pump 1403, a valve 1404, an oscillation circuit 1405, and a pump drive circuit 1406. The pulse wave sensor 1321, in addition to the sensor unit 1322 described above, also includes a power-on and voltage detection circuit 1324. In this example, the power-on and voltage detection circuit 1324 is mounted on the belt 121.

[0088] The control unit 1501 includes a CPU (Central Processing Unit) 1502, RAM (Random Access Memory) 1503, ROM (Read Only Memory) 1504, etc., and controls each component according to information processing. The storage unit 1505 is an auxiliary storage device such as a hard disk drive (HDD) or semiconductor memory (e.g., flash memory), which non-volatilely stores the program executed by the control unit 1501 (e.g., a pulse wave propagation time measurement program and a blood pressure measurement program), setting data required for program execution, blood pressure measurement results, etc. The storage medium of the storage unit 1505 stores program information such as information through electrical, magnetic, optical, mechanical, or chemical action, enabling computers, other devices, and machines to read the recorded program information. It should be noted that part or all of the program can be stored in the ROM 1504.

[0089] The battery 1506 supplies power to components such as the control unit 1501. The battery 1506 is, for example, a rechargeable battery.

[0090] Electrodes 1312 included in electrode group 1311 are respectively connected to the input terminals of switch circuit 1313. The two output terminals of switch circuit 1313 are respectively connected to the two input terminals of subtraction circuit 1314. Switch circuit 1313 receives a switch signal from control unit 1501 and connects the two electrodes 1312 specified by the switch signal to subtraction circuit 1314. Subtraction circuit 1314 subtracts the potential input from the other input terminal from the potential input from one input terminal. Subtraction circuit 1314 outputs a potential difference signal representing the potential difference between the two connected electrodes 1312 to AFE 1315. Subtraction circuit 1314 is, for example, an instrumentation amplifier. AFE 1315 includes, for example, a low-pass filter (LPF), an amplifier, and an analog-to-digital converter. The potential difference signal is filtered by the LPF, amplified by the amplifier, and converted into a digital signal by the analog-to-digital converter. The converted digital potential difference signal is provided to control unit 1501. The control unit 1501 acquires the potential difference signal output from AFE1315 in a timing sequence as an electrocardiogram.

[0091] In the energization and voltage detection circuit 1324, a high-frequency constant current flows between electrodes 1323A and 1323D. For example, the frequency of the current is 50kHz, and the current value is 1mA. In the energization and voltage detection circuit 1324, when energized between electrodes 1323A and 1323D, the voltage between electrodes 1323B and 1323C is detected, generating a detection signal. The detection signal represents the change in impedance caused by the pulse wave propagating in the artery portion opposite electrodes 1323B and 1323C. The energization and voltage detection circuit 1324 performs signal processing on the detection signal, including rectification, amplification, filtering, and analog-to-digital conversion, and provides the detection signal to the control unit 1501. The control unit 1501 acquires the detection signal output from the energization and voltage detection circuit 1324 in a timing sequence as a pulse wave signal.

[0092] Pressure sensor 1402 is connected to compression cuff 1401 via piping, and pump 1403 and valve 1404 are also connected to compression cuff 1401 via piping. It should be noted that these piping lines can be a single, shared line or separate lines. Pump 1403, for example, is a piezoelectric pump that supplies air as a fluid to compression cuff 1401 via piping to increase the pressure within compression cuff 1401. Valve 1404 is mounted on pump 1403 and is configured to control the switch according to the operating state (open / closed) of pump 1403. Specifically, when pump 1403 is turned on, valve 1404 is closed; when pump 1403 is turned off, valve 1404 is open. When valve 1404 is open, compression cuff 1401 is open to the atmosphere, and air within compression cuff 1401 is discharged into the atmosphere. It should be noted that valve 1404 functions as a check valve to prevent backflow of air. The pump drive circuit 1406 drives the pump 1403 based on the control signal received from the control unit 1501.

[0093] Pressure sensor 1402 detects the pressure (also called cuff pressure) within the compression cuff 1401 and generates an electrical signal representing the cuff pressure. The cuff pressure is, for example, pressure based on atmospheric pressure. Pressure sensor 1402 is, for example, a piezoresistive pressure sensor. Oscillating circuit 1405 oscillates based on the electrical signal from pressure sensor 1402 and outputs a frequency signal with a frequency corresponding to the electrical signal to control unit 1501. In this example, the output of pressure sensor 1402 is used to control the pressure of the compression cuff 1401 and to calculate blood pressure values ​​(including systolic and diastolic blood pressure) using an oscillometric method.

[0094] The compression cuff 1401 can be used to adjust the contact state between the electrode 1312 or the sensor portion 1322 of the pulse wave sensor 1321 and the upper arm UA. For example, when performing blood pressure measurement based on pulse wave propagation time, the compression cuff 1401 is kept in a state that contains a certain amount of air. As a result, the electrode 1312 and the sensor portion 1322 of the pulse wave sensor 1321 reliably contact the upper arm UA.

[0095] exist Figures 2 to 5 In the example shown, electrode group 1311, switch circuit 1313, subtraction circuit 1314, and AFE 1315 are equivalent to Figure 1 The electrocardiogram acquisition unit 131 and pulse wave sensor 1321 (electrode 1323 and energization and voltage detection circuit 1324) of the first blood pressure measuring unit 130 shown in the figure correspond to the pulse wave signal acquisition unit 132 of the first blood pressure measuring unit 130. In addition, the compression cuff 1401, pressure sensor 1402, pump 1403, valve 1404, oscillation circuit 1405, and pump drive circuit 1406 correspond to the second blood pressure measuring unit 140.

[0096] It should be noted that the specific hardware configuration of the blood pressure measuring device 10 can be appropriately omitted, substituted, or added depending on the implementation method. For example, the control unit 1501 may include multiple processors. The blood pressure measuring device 10 may also include a communication unit 1507 for communicating with external devices such as a user's portable terminal (e.g., a smartphone). The communication unit 1507 includes a wired communication module and / or a wireless communication module. For example, Bluetooth (registered trademark) or BLE (Bluetooth Low Energy) can be used as the wireless communication method.

[0097] Figure 6 An example of the software configuration of the blood pressure measuring device 10 of this embodiment is shown. Figure 6In the example, the blood pressure measuring device 10 includes: an electrocardiogram (ECG) measurement control unit 1601; an ECG storage unit 1602; a pulse wave measurement control unit 1603; a pulse wave signal storage unit 1604; a pulse wave propagation time calculation unit 133; a blood pressure value calculation unit 134; a blood pressure calculation formula storage unit 1605; an estimated blood pressure value storage unit 1606; a calibration determination unit 150; an indicator unit 160; a blood pressure measurement control unit 1608; a measured blood pressure value storage unit 1609; a display control unit 1607; an indicator input unit 1610; a calibration processing unit 170; and a calibration determination reference value storage unit 1611. The electrocardiogram measurement control unit 1601, pulse wave measurement control unit 1603, pulse wave propagation time calculation unit 133, blood pressure value calculation unit 134, calibration determination unit 150, indicator unit 160, blood pressure measurement control unit 1608, display control unit 1607, indicator input unit 1610, and calibration processing unit 170 perform the following processing by having the control unit 1501 of the blood pressure measuring device 10 execute a program stored in the storage unit 1505. When the control unit 1501 executes the program, it expands the program in the RAM 1503. Furthermore, the control unit 1501 interprets and executes the program expanded in the RAM 1503 via the CPU 1502 to control each component. The electrocardiogram storage unit 1602, pulse wave signal storage unit 1604, blood pressure calculation storage unit 1605, estimated blood pressure value storage unit 1606, measured blood pressure value storage unit 1609, and calibration judgment benchmark value storage unit 1611 are implemented by the storage unit 1505.

[0098] The electrocardiogram (ECG) measurement control unit 1601 controls the switching circuit 1313 to acquire an ECG. Specifically, the ECG measurement control unit 1601 generates a switching signal for selecting two electrodes 1312 out of six electrodes 1312 and provides this switching signal to the switching circuit 1313. The ECG measurement control unit 1601 acquires the potential difference signal obtained using the two selected electrodes 1312 and stores the timing data of the acquired potential difference signal as an ECG in the ECG storage unit 1602.

[0099] When the user wears the blood pressure measuring device 10 on their upper arm, the electrocardiogram (ECG) measurement control unit 1601 determines the most suitable electrode pair for acquiring an ECG. For example, the ECG measurement control unit 1601 acquires ECGs for each electrode pair individually and determines the electrode pair that provides the ECG with the largest R-wave amplitude as the most suitable electrode pair. Then, the ECG measurement control unit 1601 uses the most suitable electrode pair to measure the ECG.

[0100] The pulse wave measurement control unit 1603 controls the energization and voltage detection circuit 1324 to acquire a pulse wave signal. Specifically, the pulse wave measurement control unit 1603 instructs the energization and voltage detection circuit 1324 to allow current to flow between electrodes 1323A and 1323D, and acquires a detection signal representing the voltage between electrodes 1323B and 1323C detected while current is flowing between electrodes 1323A and 1323D. The pulse wave measurement control unit 1603 stores the timing data of the detection signal as a pulse wave signal in the pulse wave signal storage unit 1604.

[0101] The pulse wave propagation time calculation unit 133 reads the electrocardiogram (ECG) from the ECG storage unit 1602 and the pulse wave signal from the pulse wave signal storage unit 1604, and calculates the pulse wave propagation time based on the time difference between the waveform feature points of the ECG and the waveform feature points of the pulse wave signal. For example, the pulse wave propagation time calculation unit 133 detects the time (moment) of the peak point corresponding to the R wave from the ECG and detects the time (moment) of the rising point from the pulse wave signal, and calculates the difference between the time of the rising point and the time of the peak point as the pulse wave propagation time.

[0102] It should be noted that the pulse wave propagation time calculation unit 133 can correct the aforementioned time difference based on the pre-ejection period (PEP) and output the corrected time difference as the pulse wave propagation time. For example, if the pre-ejection period is considered to be fixed, the pulse wave propagation time calculation unit 133 can also calculate the pulse wave propagation time by subtracting a predetermined value from the aforementioned time difference.

[0103] The peak point corresponding to the R wave is an example of a waveform feature point in an electrocardiogram (ECG). A waveform feature point in an ECG can also be a peak point corresponding to the Q wave or the S wave. The R wave appears as a more pronounced peak than the Q or S wave, therefore the timing of the R wave peak point can be determined more accurately. Therefore, the R wave peak point is preferred as a waveform feature point in an ECG. Furthermore, the rising point is an example of a waveform feature point in a pulse wave signal. A waveform feature point in a pulse wave signal can be a peak point. The pulse wave signal changes slowly over time, therefore errors can easily occur when determining the timing of waveform feature points in the pulse wave signal.

[0104] When reference Figure 6 At that time, the blood pressure calculation unit 134 calculates the estimated blood pressure value based on the pulse wave propagation time calculated by the pulse wave propagation time calculation unit 133 and the blood pressure calculation formula. The blood pressure calculation unit 134 uses the algorithm for blood pressure calculation (specifically, for example, the formula (1) described above) stored in the blood pressure calculation formula storage unit 1605 as the blood pressure calculation formula. The blood pressure calculation unit 134 stores the calculated blood pressure value in the estimated blood pressure value storage unit 1606 in association with time information.

[0105] It should be noted that the blood pressure calculation formula is not limited to the formula (1) mentioned above. For example, the blood pressure calculation formula can be the following formula.

[0106] SBP = B1 / PTT 2 +B2 / PTT+B3×PTT+B4……(2)

[0107] Here, B1, B2, B3, and B4 are parameters.

[0108] The calibration determination unit 150 determines whether the conditions for recommending blood pressure measurement for the user are met based on a specified characteristic quantity related to blood pressure estimation, such as the pulse wave propagation time calculated by the pulse wave propagation time calculation unit 133, and a specified reference value related to that characteristic quantity stored in the calibration determination reference value storage unit 1611. Even if the blood pressure calculation formula is calibrated when the device is first used, if the characteristic quantity related to the estimated blood pressure value calculation deviates from the specified reference value (upper and lower limit threshold), it is considered that the accuracy of the calculated estimated blood pressure value will decrease. Therefore, in this case, it is ideal to perform an accurate blood pressure measurement based on the second blood pressure measurement unit 140, compare it with the measured blood pressure value, thereby confirming the accuracy of the estimated blood pressure value, and if the accuracy is low (i.e., the difference between the measured blood pressure value and the estimated blood pressure value is large), to perform blood pressure calculation formula calibration.

[0109] It should be noted that, as another example, the calibration determination unit 150 can also determine whether the blood pressure change rate, as a specified characteristic quantity, exceeds a threshold. The blood pressure change rate is, for example, the change in blood pressure value per unit time. Specifically, the calibration determination unit 150 determines whether the difference between the latest blood pressure value and the blood pressure value from a unit time ago exceeds a threshold. When the latest systolic blood pressure value is set as SBP0, the systolic blood pressure value from a unit time ago is set as SBP1, and the threshold is set as V... th At that time, the calibration determination unit 150 determines whether the condition SBP0-SBP1>V is met. th This conditional expression. The unit time is, for example, 30 seconds, and the threshold is, for example, 20 [mmHg]. When the latest pulse wave propagation time is set as PTT0, and the pulse wave propagation time a unit time ago is set as PTT1, the above conditional expression, when transformed using formula (1), becomes A1(1 / PTT0). 2 -1 / PTT1 2 )>V th .

[0110] That is, the calibration determination unit 150 can use the pulse wave propagation time itself, or it can use the blood pressure value calculated based on the pulse wave propagation time. It should be noted that the calibration determination unit 150 can also determine whether the difference between the latest blood pressure value and the blood pressure value 30 beats ago (before a specified heart rate) exceeds a threshold. In other examples, the calibration determination unit 150 determines whether the latest systolic blood pressure value exceeds a threshold (e.g., 150 mmHg). This threshold can be fixed or variable. For example, the higher the user's average blood pressure, the higher the threshold value should be.

[0111] When the calibration determination unit 150 decides to acquire the measured blood pressure value, the instruction unit 160 outputs information instructing the execution of the blood pressure measurement performed by the second blood pressure measuring unit 140. For example, the instruction unit 160 provides an instruction signal to the display control unit 1607 so that a message urging the execution of the blood pressure measurement is displayed on the display unit 1222. Furthermore, the instruction unit 160 outputs a control signal to control the drive circuit of the driving sound generator to generate a notification tone. It should be noted that the instruction unit 160 sends the instruction signal to the user's portable terminal via the communication unit 1507, thereby urging the user to perform the blood pressure measurement via the portable terminal.

[0112] The instruction input unit 1610 receives instructions input from the user using the operation unit 1221. For example, when performing an operation to instruct the blood pressure measurement, the instruction input unit 1610 provides a start instruction for the blood pressure measurement to the blood pressure measurement control unit 1608. It should be noted that the instruction input unit 1610 and the operation unit 1221 correspond to the operation input unit of the present invention.

[0113] The blood pressure measurement control unit 1608 controls the pump drive circuit 1406 to perform blood pressure measurement. Upon receiving a start instruction for blood pressure measurement from the instruction input unit 1610, the blood pressure measurement control unit 1608 drives the pump 1403 via the pump drive circuit 1406. This initiates the supply of air to the compression cuff 1401. The compression cuff 1401 inflates, thereby compressing the user's upper arm. The blood pressure measurement control unit 1608 uses a pressure sensor 1402 to monitor the cuff pressure. During the pressurization process of supplying air to the compression cuff 1401, the blood pressure measurement control unit 1608 calculates the blood pressure value using an oscillometric method based on the pressure signal output from the pressure sensor 1402. The blood pressure value includes, but is not limited to, systolic blood pressure (SBP) and diastolic blood pressure (DBP). The blood pressure measurement control unit 1608 stores the calculated blood pressure value in a measured blood pressure value storage unit 1609, linking it to time information. The blood pressure measurement and control unit 1608 calculates the blood pressure value and the pulse rate simultaneously. When the blood pressure value calculation is complete, the blood pressure measurement and control unit 1608 stops the pump 1403 via the pump drive circuit 1406. As a result, air is expelled from the compression cuff 1401 through the valve 1404.

[0114] The display control unit 1607 controls the display unit 1222. For example, the display control unit 1607 receives an instruction signal from the instruction unit 160 and displays the message included in the instruction signal on the display unit 1222. In addition, after the blood pressure measurement performed by the blood pressure measurement control unit 1608 is completed, the display control unit 1607 displays the blood pressure measurement result on the display unit 1222.

[0115] The calibration processing unit 170 performs blood pressure calculation calibration based on the estimated blood pressure value obtained by the blood pressure calculation unit 134 and the measured blood pressure value obtained by the blood pressure measurement control unit 1608. It should be noted that, in addition to this, the blood pressure calculation calibration performed by the calibration processing unit 170 can also be performed as an initial setting when the user wears the blood pressure measuring device 10. The correlation between pulse wave propagation time and blood pressure value varies from person to person. Furthermore, the correlation changes depending on the position of the blood pressure measuring device 10 on the user's upper arm. For example, even for the same user, the correlation will change when the blood pressure measuring device 10 is positioned closer to the shoulder than when it is positioned closer to the elbow. To reflect such changes in the correlation, the blood pressure calculation calibration is performed.

[0116] The calibration processing unit 170 also modifies the reference values ​​stored in the calibration determination reference value storage unit 1611. Specifically, for example, it calculates the difference between the estimated blood pressure value and the measured blood pressure value when the calibration determination unit 150 determines to obtain the measured blood pressure value. If the difference is large, the reference value is changed in a way that increases the frequency of calibration; if the difference is small, the reference value is changed in a way that decreases the frequency of calibration.

[0117] It should be noted that in this embodiment, an example has been described where all functions of the blood pressure measuring device 10 are implemented using a general-purpose processor. However, some or all of the functions may also be implemented using one or more dedicated processors.

[0118] (Example of action)

[0119] Next, based on Figure 7 An example of the operation of the blood pressure measuring device 10 of this embodiment will be described. Figure 7This is a flowchart illustrating an example of the processing flow performed by the blood pressure measuring device 10. First, when a user uses the blood pressure measuring device 10 for the first time, an initial calibration of the blood pressure calculation formula is performed (S101). In this process, the control unit 1501 operates as a calibration processing unit 170. When the number of parameters included in the blood pressure calculation formula is set to N, N or more combinations of pulse wave propagation time measurements and blood pressure measurements are required. The aforementioned blood pressure calculation formula (1) has two parameters, A1 and A2. In this case, for example, when the user is at rest, the control unit 1501 acquires a combination of pulse wave propagation time measurements and blood pressure measurements, then instructs the user to exercise, and acquires a combination of pulse wave propagation time measurements and blood pressure measurements after the exercise. Thus, two combinations of pulse wave propagation time measurements and blood pressure measurements are acquired. The control unit 1501 determines parameters A1 and A2 based on the two combinations of the acquired pulse wave propagation time measurements and blood pressure measurements.

[0120] Next, a reference value is set to determine whether it is necessary to obtain the measured blood pressure value (S102). The reference value at this time can be calculated based on the determined parameters A1 and A2, or it can be a preset universal reference value. The reference value set here is stored in the calibration judgment reference value storage unit 1611.

[0121] After the initial calibration, blood pressure measurement based on pulse wave propagation time (estimated) can be performed. The following loop processing L1 is repeated until the specified termination condition is met, thereby performing continuous / non-invasive blood pressure measurement.

[0122] In loop processing L1, the following process is repeatedly executed. First, the control unit 1501 continuously calculates the pulse wave propagation time to calculate the estimated blood pressure value (S103). Furthermore, based on the calculated pulse wave propagation time and the blood pressure calculation formula stored in the blood pressure calculation formula storage unit, the estimated blood pressure value is calculated (S104). Then, a process is performed to determine whether the subsequently calculated pulse wave propagation time deviates from the reference value stored in the calibration determination reference value storage unit 1611 (S105). The reference value can be, for example, an upper threshold or a lower threshold for the pulse wave propagation time. Alternatively, it can be an upper or lower threshold that defines a specified numerical range. That is, in step S105, if the reference value is the upper threshold, it is determined whether the pulse wave propagation time exceeds the reference value; if the reference value is the lower threshold, it is determined whether the pulse wave propagation time is less than the reference value; and if the reference value is either the upper or lower threshold, it is determined whether the pulse wave propagation time is within the specified numerical range.

[0123] If it is determined in step S105 that the value has not deviated from the reference value, the process returns to step S103 and repeats thereafter. Conversely, if it is determined in step S105 that the value has deviated from the reference value, the process proceeds to step S106, where it is determined that the measured blood pressure value obtained by the second blood pressure measuring unit 140 should be acquired for the calibration of the blood pressure calculation formula. It should be noted that in the process of step S105, the control unit 1501 functions as the calibration determination unit 150.

[0124] In step S106, the control unit 1501 performs control to output information indicating the execution of the blood pressure measurement performed by the second blood pressure measuring unit 140. In step S106, the control unit 1501 operates as an instruction unit 160. Then, when a start instruction for blood pressure measurement performed by the user is received via the operation unit 1221, processing is performed to obtain the measured blood pressure value by the second blood pressure measuring unit 140 (S107). In step S107, the control unit 1501 operates as a blood pressure measurement control unit 1608.

[0125] When the measured blood pressure value is obtained, the control unit 1501 calibrates the blood pressure calculation formula stored in the blood pressure calculation formula storage unit 1605 based on it (S108), and performs a process to determine whether the difference between the estimated blood pressure value and the measured blood pressure value is above a specified threshold (S109).

[0126] Here, if the difference is above a threshold, the reference value stored in the calibration judgment reference value storage unit 1611 is changed in a way that increases the frequency of the indicator 160 indicating the acquisition of the measured blood pressure value (S110). Specifically, when the reference value is an upper or lower limit threshold of the pulse wave propagation time, the value is changed in a way that decreases the upper limit threshold and increases the lower limit threshold, that is, the numerical range determined by the upper and lower limit thresholds is narrowed. In this way, the calculated pulse wave propagation time is more likely to deviate from the upper or lower limit thresholds than before the reference value was changed, and as a result, the frequency of the indicator 160 indicating the acquisition of the measured blood pressure value increases.

[0127] On the other hand, if it is determined in step S108 that the difference is less than the threshold, the reference value is changed in a way that reduces the frequency of the indicator 160 indicating the acquisition of the measured blood pressure value (S111). Specifically, contrary to the case in step S110 above, if the reference value is an upper or lower limit threshold of the pulse wave propagation time, the upper limit threshold is increased and the lower limit threshold is decreased, that is, the numerical range determined by the upper and lower limit thresholds is expanded. In this way, the calculated pulse wave propagation time is less likely to deviate from the upper or lower limit thresholds than before the reference value was changed, and as a result, the frequency of the indicator 160 indicating the acquisition of the measured blood pressure value is reduced.

[0128] When the processing of step S110 or step S111 is executed, the series of loop processing L1 ends, and the process returns to the beginning of loop processing L1 (i.e., step S103) to execute a new loop processing L1. It should be noted that in the processing of steps S108 to S111, the control unit 1501 functions as the calibration processing unit 170.

[0129] It should be noted that, Figure 7 The processing procedure shown is illustrative and can be modified as appropriate. For example, in the above process, after the blood pressure calculation formula is calibrated in step S108, the process proceeds to step S109 to determine whether the difference between the measured blood pressure value and the estimated blood pressure value is above a specified threshold. However, this process can be replaced by first determining whether the difference between the measured blood pressure value and the estimated blood pressure value is above a specified threshold. Based on this, if the difference is less than the specified threshold, the calibration of the blood pressure calculation formula may not be performed.

[0130] Furthermore, in the above processing, if the difference in step S109 is above a predetermined threshold, the reference value is changed by increasing the calibration frequency; otherwise, the reference value is changed by decreasing the calibration frequency. However, the threshold can also be set using an upper and lower limit. That is, if the difference is above the upper threshold, the reference value is changed by increasing the calibration frequency; if the difference is below the lower threshold, the reference value is changed by decreasing the calibration frequency; if the difference does not deviate from the upper or lower threshold, the reference value is not changed.

[0131] (Effect)

[0132] As described above, in the blood pressure measuring device 10 of this embodiment, the electrode assembly 1311 and the sensor portion 1322 of the pulse wave sensor 1321 are both disposed on the strap 121. Therefore, both the electrode assembly 1311 and the pulse wave sensor 1321 can be fitted to the user simply by wrapping the strap 121 around the upper arm. Thus, the user can easily wear the blood pressure measuring device 10. Since the user can wear only one device, the user's resistance to wearing the blood pressure measuring device 10 is reduced.

[0133] Furthermore, since the blood pressure measuring device 10 is worn on the upper arm, blood pressure can be measured at approximately the same height as the heart. Therefore, there is no need for height correction of the obtained blood pressure measurement results. In addition, when the blood pressure measuring device 10 is an upper arm type, it can be hidden in the sleeve of clothing, making its wearing inconspicuous.

[0134] Furthermore, the pulse wave propagation time is calculated based on the electrocardiogram and the pulse wave signal obtained in relation to the upper arm, thus obtaining the pulse wave propagation time in relation to a long distance such as from the heart to the upper arm. This improves robustness against errors arising from the time difference between the waveform feature points of the electrocardiogram and the waveform feature points of the pulse wave signal. Moreover, the electrode assembly 1311 is disposed in the central side portion 1217A of the band 121, and the sensor portion 1322 of the pulse wave sensor 1321 is disposed in the peripheral side portion 1217B of the band 121. This configuration ensures a longer pulse wave propagation distance and allows for the acquisition of electrocardiograms with a high signal-to-noise ratio (SN ratio). This further improves robustness. As a result, the pulse wave propagation time can be accurately measured, improving the reliability of the blood pressure value calculated based on the pulse wave propagation time.

[0135] Furthermore, in this embodiment, both pulse wave propagation time-based and oscillometric blood pressure measurements can be performed using a single device, offering high convenience for the user. Moreover, since the second blood pressure measuring unit 140 is integrated with the first blood pressure measuring unit 130, and the blood pressure calculation formula is calibrated based on the measured blood pressure value obtained from the second blood pressure measuring unit 140, the blood pressure calculation formula can be calibrated independently using the blood pressure measuring device 10. Therefore, the calibration of the blood pressure calculation formula can be easily performed.

[0136] Furthermore, based on the results of continuous blood pressure measurements obtained by the first blood pressure measuring unit 130, it is determined whether to obtain the user's measured blood pressure value (i.e., whether the algorithm used for blood pressure value calculation needs to be calibrated). If the conditions are met, the user is notified that a blood pressure measurement performed by the second blood pressure measuring unit 140 will be performed. Therefore, the user can perform an accurate blood pressure measurement when a blood pressure measurement is recommended.

[0137] Furthermore, by changing the reference value of a specified characteristic quantity that serves as the criterion for determining whether to obtain a measured blood pressure value based on the difference between the measured blood pressure value and the estimated blood pressure value (i.e., the accuracy of the estimated blood pressure value), the frequency of obtaining measured blood pressure values ​​can be optimized. Thus, a technique can be provided that allows for repeated calibration of the blood pressure calculation algorithm, improves the accuracy of blood pressure estimation based on the user, and optimizes the frequency of calibrating the blood pressure calculation algorithm.

[0138] (Modified Example)

[0139] In the above embodiments, the pulse wave sensor employs an impedance method that detects changes in impedance associated with changes in arterial volume. It should be noted that the pulse wave sensor can also employ other measurement methods such as photoelectric, piezoelectric, or radio-wave methods. In the photoelectric method embodiment, the pulse wave sensor includes: a light-emitting element that illuminates light through the artery passing through the measurement site; and a photodetector that detects reflected or transmitted light, wherein the pulse wave sensor detects changes in light intensity associated with changes in arterial volume. In the piezoelectric method embodiment, the pulse wave sensor includes: a piezoelectric element disposed in a strip in contact with the measurement site, wherein the pulse wave sensor detects changes in pressure associated with changes in arterial volume. In the radio-wave method embodiment, the pulse wave sensor includes: a transmitting element that transmits radio waves through the artery passing through the measurement site; and a receiving element that receives the reflected wave of the radio waves, detecting the phase difference between the transmitted and reflected waves associated with changes in arterial volume.

[0140] The blood pressure measuring device 10 may further include: a compression cuff for adjusting the contact state between the sensor portion 1322 of the pulse wave sensor 1321 and the upper arm; a pump for supplying air to the compression cuff; a pump drive circuit for driving the pump; and a pressure sensor for detecting the pressure within the compression cuff. The compression cuff is located at the distal end 1218C of the belt 121. In this case, the compression cuff 1401 may be located, for example, at the middle portion 1218B of the belt 121.

[0141] The part involved in measuring pulse wave propagation time can also be implemented as a separate device. In one embodiment, a pulse wave propagation time measuring device is provided, comprising a cuff 120, an electrocardiogram acquisition unit 131, a pulse wave signal acquisition unit 132, and a pulse wave propagation time calculation unit 133. This pulse wave propagation time measuring device may also include a calibration determination unit 150 and an indicator unit 160. In order to press the electrode 1312 and the pulse wave sensor 1321 onto the upper arm, the pulse wave propagation time measuring device may also include a pressing cuff, a pump, and a pump drive circuit.

[0142] The blood pressure measuring device 10 may also be without the second blood pressure measuring unit 140. In embodiments where the blood pressure measuring device 10 is without the second blood pressure measuring unit 140, in order to perform calibration of the blood pressure calculation formula, it is necessary to input the blood pressure value obtained by measuring using another blood pressure monitor into the blood pressure measuring device 10.

[0143] <Implementation Method 2>

[0144] It should be noted that in the above embodiment 1, the present invention is used as a blood pressure measuring device, which includes a storage unit, a blood pressure value calculation unit, a display unit, etc., and all functions are integrated into one device. However, the present invention can also be used as a blood pressure measuring system in which some of these components and functions are separated. Figure 8 and Figure 9 An example of this blood pressure measurement system is shown in the figure.

[0145] Figure 8 A schematic diagram of the blood pressure measurement system 2 according to this embodiment is shown. (As shown...) Figure 8 As shown, the blood pressure measurement system 2 includes: a sensor device 21, worn on the user's upper arm; and an information processing terminal 22, which processes the biological information acquired by the sensor device 21. The sensor device 21, though not shown, is a wearable device equipped with multiple electrodes (electrocardiogram sensors) and a pulse wave sensor, and is used by being fixed to the user's upper arm using a strap or similar fixing unit. The information processing terminal 22 can be any information processing terminal as long as it can communicate with the sensor device 21, but... Figure 8 As shown, smartphones can also be used as information processing terminals 22.

[0146] Figure 9 This is a block diagram illustrating the functional configuration of the sensor device 21 and the information processing terminal 22 in the blood pressure measurement system 2. The sensor device 21 includes functional units such as an electrode unit 211, a pulse wave sensor unit 212, a control unit 210, a storage unit 213, an operation unit 214, a power supply unit 215, and a communication unit 216. Furthermore, the control unit 210, as its functional module, includes an electrocardiogram acquisition unit 201 and a pulse wave signal acquisition unit 202.

[0147] The pulse wave sensor unit 212 and the pulse wave signal acquisition unit 202 in the sensor device 21 can, for example, employ a photoelectric method. Specifically, the pulse wave sensor unit 212 includes: a light-emitting element that illuminates light through an artery passing through the measurement site; and a photodetector that detects reflected or transmitted light. The pulse wave sensor unit 212 detects changes in light intensity as the volume of the artery changes (neither shown). Furthermore, the electrode unit 211 and the electrocardiogram acquisition unit 201 can adopt the same configuration as the blood pressure measuring device 10 of Embodiment 1, therefore detailed descriptions are omitted.

[0148] Furthermore, the storage unit 213 only has main storage devices such as RAM and ROM, and its storage capacity is limited. The operation unit 214 also has a limited configuration such as a power switch, and its structure is simple. The power supply unit 215 can, for example, use a rechargeable secondary battery. In addition, the communication unit 216 includes a wired communication module and / or a wireless communication module. It should be noted that the connection terminal for wired communication can also be configured as the charging terminal for the power supply unit 215.

[0149] Thus, the sensor device 21 in this embodiment has only a very limited function of acquiring biological information for calculating estimated blood pressure values. Therefore, the electrocardiogram signals and pulse wave signals measured by each sensor unit are transmitted in real time to the information processing terminal 22 via the communication unit 216.

[0150] The information processing terminal 22 includes a control unit 220, a display unit 225, an operation unit 226, a communication unit 227, and a storage unit 228. Furthermore, the control unit 220 includes functional modules for a blood pressure value calculation unit 221, a calibration determination unit 222, a measured blood pressure value acquisition unit 223, and a calibration processing unit 224.

[0151] The information processing terminal 22 communicates with the sensor device 21 via the communication unit 227, receiving the user's electrocardiogram (ECG) signal and pulse wave signal measured by the sensor device 21. The communication standard is not particularly limited, but communication can also be conducted via wireless communication standards such as Bluetooth (registered trademark), Wi-Fi (registered trademark), and infrared communication. It should be noted that the hardware configuration of the information processing terminal 22 is the same as that of a smartphone; for example, the touch panel display serves as both the display unit 225 and the operation unit 226.

[0152] The biological information received from the sensor device 21 via the communication unit 227 is stored in the storage unit 228, and various processes such as calculating the estimated blood pressure value are performed based on the stored information. It should be noted that the storage unit 228 is similar to the storage unit 1505 of the blood pressure measuring device 10 in Embodiment 1, storing not only electrocardiogram and pulse wave signals, but also information such as the algorithm for calculating the blood pressure value, the judgment benchmark value for whether calibration is required, the estimated blood pressure value, and the measured blood pressure value.

[0153] The blood pressure calculation unit 221, calibration determination unit 222, and calibration processing unit 224 are the same as those in the blood pressure measuring device 10 of Embodiment 1. They are functional modules that perform calculation processing of estimated blood pressure values, determination processing of whether algorithm calibration is needed using measured blood pressure values, algorithm calibration processing for blood pressure calculation, and reference value change processing to determine whether calibration is needed. These processes are the same as in Embodiment 1, so further explanation is omitted here.

[0154] When the calibration determination unit 222 determines that calibration using the blood pressure calculation algorithm based on the measured blood pressure value is required, the measured blood pressure value acquisition unit 223 performs the process of acquiring the measured blood pressure value. In this embodiment, the user is notified to input the measured blood pressure value, for example, via the display unit 225 or a speaker (not shown). The user measures the measured blood pressure value using another device (not shown) capable of accurate blood pressure measurement such as oscillometric methods, and inputs the blood pressure value into the information processing terminal 22 by operating the operation unit 226. That is, the measured blood pressure value acquisition unit 223 acquires the measured blood pressure value via the operation unit 226. The acquired measured blood pressure value is stored in the storage unit 228.

[0155] The blood pressure measurement system 2 of this embodiment is configured such that: a sensor device 21 detects biological information (e.g., electrocardiogram and pulse wave signals) for continuous estimation of blood pressure values; and an information processing terminal 22 performs actual blood pressure value calculation, determines whether calibration is needed, and performs algorithm calibration. This configuration simplifies the construction of wearable devices and further reduces the burden on users wearing such devices. Furthermore, it effectively utilizes existing information processing terminals, similar to smartphones, thus reducing the cost for users when implementing the system.

[0156] <Implementation Method 3>

[0157] In the above embodiments, an example of daily and continuous blood pressure measurement using a wearable dedicated blood pressure measuring device has been described, but the present invention can also be implemented without using such a dedicated blood pressure measuring device. Figure 10 and Figure 11 An example of a blood pressure measurement system in this situation is shown in the figure.

[0158] Figure 10 A schematic diagram of the blood pressure measurement system 3 according to this embodiment is shown. (As shown) Figure 10 As shown, the blood pressure measurement system 3 comprises a body composition analyzer 31, a blood pressure measuring device 32, and a server 33 connected via a network N. It should be noted that the network N can be, for example, a WAN (Wide Area Network), such as the Internet, or another communication network. Furthermore, the network N can include telephone communication networks such as mobile phones, and wireless communication networks such as Wi-Fi (registered trademark).

[0159] The body composition analyzer 31 is generally configured to have a main body 31A and a handle 31B. Furthermore, although not shown, in addition to a communication unit for communication, it also includes sensors (e.g., strain gauges, electrodes, velocity sensors, etc.) for acquiring various biological information such as weight, body fat percentage, electrocardiogram, pulse wave signal, and ballistocardiogram (BCG), an output unit such as an LCD display, an input unit such as operation buttons, and a power supply unit.

[0160] The blood pressure measuring device 32 is a general household blood pressure measuring device that generally has a main body 32A and a cuff 32B. It includes various elements for blood pressure measurement based on the oscillometric method, such as a pressure sensor, a pressable cuff, and a pump, as well as an output unit such as an LCD display and an input unit such as operation buttons.

[0161] Server 33 is composed of a general server computer, equipped with processors such as CPU, main storage devices such as RAM and ROM, and auxiliary storage devices such as EPROM, HDD, and removable media.

[0162] Figure 11 This is a block diagram illustrating the functional configuration of the blood pressure measurement system 3. The body composition analyzer includes an electrocardiogram acquisition unit 311, a pulse wave signal acquisition unit 312, a pulse wave propagation time calculation unit 313, a blood pressure value calculation unit 314, a calibration determination unit 315, a storage unit 316, and a communication unit 317.

[0163] The electrocardiogram (ECG) acquisition unit 311 acquires the user's ECG via electrodes disposed on the upper surface of the main body 31A and the handle 31B of the body composition analyzer 31. The pulse wave signal acquisition unit 312 acquires the user's pulse wave signal (peripheral pulse wave) via a pulse wave sensor disposed on the handle 31B. The pulse wave sensor can be impedance type or photoelectric type. The acquired ECG and pulse wave signal are stored in the storage unit 316. In addition to this biological information, the storage unit 316 also stores, similarly to the blood pressure measuring device 10 of Embodiment 1, a blood pressure calculation algorithm and a reference value for determining whether calibration is required.

[0164] The pulse wave propagation time calculation unit 313 reads the electrocardiogram and pulse wave signal from the storage unit 316 and calculates the pulse wave propagation time based on the time difference between the waveform feature points of the electrocardiogram and the waveform feature points of the pulse wave signal. Furthermore, the blood pressure value calculation unit 314 calculates the blood pressure value based on the calculated pulse wave propagation time and the blood pressure calculation algorithm stored in the storage unit 316. Additionally, the calibration determination unit 315 determines whether to calibrate the blood pressure calculation algorithm based on the calculated pulse wave propagation time and a predetermined reference value stored in the storage unit 316. These processes are the same as those in the blood pressure measuring device 10 of Embodiment 1, and therefore detailed descriptions are omitted here.

[0165] If the calibration determination unit 315 determines that the blood pressure calculation algorithm needs calibration, it notifies the user of this via a display unit (not shown) and sends the estimated blood pressure value when calibration is determined to be required to the server 33 via the communication unit 317 and the network N.

[0166] The blood pressure measuring device 32 includes a blood pressure measuring unit 321 and a communication unit 322 as functional units. The blood pressure measuring unit 321 is a functional unit that performs accurate blood pressure measurement using methods such as oscillometric methods. It can adopt the same configuration as the second blood pressure measuring unit 140 in the blood pressure measuring device 10 of Embodiment 1, so its description is omitted here. The measured blood pressure value measured by the blood pressure measuring unit 321 is transmitted to the server 33 via the communication unit 322 and the network N.

[0167] Server 33 includes a calibration processing unit 331, a storage unit 332, and a communication unit 333. Information (estimated blood pressure value, measured blood pressure value, etc.) sent from body composition analyzer 31 and blood pressure measuring device 32 and received by communication unit 333 is stored in storage unit 332. Calibration processing unit 331 performs calibration processing for the blood pressure calculation algorithm of body composition analyzer 31 based on the estimated blood pressure value and measured blood pressure value stored in storage unit 332. Specifically, it calculates more appropriate parameter values ​​based on estimated blood pressure value and measured blood pressure value, and sends the data of the new parameters calculated in this way to body composition analyzer 31 via communication unit 333 and network N. Furthermore, it calibrates the blood pressure calculation algorithm by updating the blood pressure calculation algorithm stored in storage unit 316 of body composition analyzer 31 to a new algorithm using the new parameters.

[0168] It should be noted that, similar to Embodiments 1 and 2, the calibration processing unit 331 also performs the benchmark value change processing for the determination processing performed by the calibration determination unit 315. In this regard, similar to algorithm calibration, the server 33 calculates a new benchmark value and sends the calculated new benchmark value to the body composition analyzer 31, storing the new benchmark value in the storage unit 316, thereby changing the benchmark value.

[0169] As described above, in the blood pressure measurement system 3 of this embodiment, biological information for calculating the estimated blood pressure value is not acquired using a dedicated device, but rather using a general-purpose body composition analyzer 31. Furthermore, the body composition analyzer 31 does not have the calibration processing unit 331 function; this function is performed in the server 33. Therefore, complex computational processing for algorithm calibration is not required on the measuring device side, allowing for the measurement (estimation) of blood pressure values ​​using a general-purpose body composition analyzer, and enabling appropriate algorithm calibration. In other words, the accuracy of the estimated blood pressure value can be maintained relatively well using a general-purpose body composition analyzer. It should be noted that in this embodiment, the body composition analyzer 31 has a handle portion 31B, but a body composition analyzer without a handle portion 31B can also be used.

[0170] <Other>

[0171] The above-described embodiments are merely illustrative of the present invention, and the present invention is not limited to the specific embodiments described above. The present invention can be modified and combined in various ways within its technical concept. For example, in the examples described above, the characteristic quantity used to determine whether calibration of the blood pressure calculation algorithm is required is the pulse wave propagation time, but the determination of whether algorithm calibration is required can also be based on other characteristic quantities. For example, in embodiment 3, information such as weight, BMI, impact graph, and pulse wave velocity (PWV) can be obtained from various sensors provided with the body composition analyzer 31, and these characteristic quantities can also be used to estimate blood pressure. That is, these characteristic quantities can also be used in determining whether algorithm calibration is required. In addition, the height of the inflection point of the pulse wave or electrocardiogram waveform, the inclination between two points of the inflection point, the area between the two points of the inflection point, and their ratio can also be used as characteristic quantities for determining whether algorithm calibration is required. In addition, information such as heart rate (e.g., the difference from the previous heart rate, the difference from the average heart rate), user's personal attributes (height, age, medication history, etc.), information about the conditions at the time of measurement (user's activity level, posture, etc.), and environmental information (season, external temperature, etc.) can also be used as features.

[0172] Furthermore, in Embodiment 1 described above, an example of changing either the upper or lower limit when the reference value is an upper or lower threshold related to the pulse wave propagation time was given. However, the change of the reference value is not limited to this, and various modes can be set. For example, the reference value can be set to only the upper threshold or only the lower threshold. When the lower threshold is set, increasing the reference value increases the frequency of calibration, and decreasing the reference value decreases the frequency of calibration. Furthermore, when the reference value is an upper or lower threshold, only the upper threshold or only the lower threshold can be changed. Even in this case, the width of the numerical range that the feature quantity should include can be changed, and the frequency of calibration can be changed accordingly.

[0173] Furthermore, the device for measuring biological information is not limited to the devices exemplified in the above embodiments; for example, it could be a device such as a smartwatch. Additionally, the measurement site is not limited to the upper arm or wrist; measuring devices worn on other parts of the body, such as the thigh or ankle, can also be used.

[0174] Explanation of reference numerals in the attached figures

[0175] 10: Blood pressure measuring device;

[0176] 120: Belt section; 121: Belt; 122: Main body;

[0177] 130: First blood pressure measurement unit; 131: Electrocardiogram acquisition unit; 132: Pulse wave signal acquisition unit; 133: Pulse wave propagation time calculation unit; 134: Blood pressure value calculation unit;

[0178] 140: Second blood pressure measuring unit; 150: Calibration and judgment unit; 160: Indicator unit;

[0179] 1210A: Inner fabric; 1210B: Outer fabric; 1213: Loop surface; 1214: Hook surface; 1221: Operating section; 1222: Display section;

[0180] 1311: Electrode assembly; 1312: Electrode; 1313: Switching circuit; 1314: Subtraction circuit; 1315: Analog front end; 1321: Pulse wave sensor; 1322: Sensor unit; 1323A~1323D: Electrodes; 1324: Power-on and voltage detection circuit;

[0181] 1401: Pressing cuff; 1402: Pressure sensor; 1403: Pump; 1404: Valve; 1405: Oscillating circuit; 1406: Pump drive circuit;

[0182] 1501: Control unit; 1502: CPU; 1503: RAM; 1504: ROM;

[0183] 1505: Storage unit; 1506: Battery; 1507: Communication unit;

[0184] 1601: Electrocardiogram (ECG) measurement control unit; 1602: ECG storage unit; 1603: Pulse wave measurement control unit; 1604: Pulse wave signal storage unit; 1605: Blood pressure calculation storage unit; 1606: Estimated blood pressure value storage unit; 1607: Display control unit; 1608: Blood pressure measurement control unit; 1609: Measured blood pressure value storage unit; 1610: Indicator input unit; 1611: Calibration judgment benchmark value storage unit;

[0185] UA: upper arm; UAA: brachial artery; UAB: upper arm bone;

[0186] 2, 3: Blood pressure measurement system;

[0187] 21: Sensor device; 22: Information processing terminal;

[0188] 31: Body composition analyzer; 31A: Main body; 31B: Handle;

[0189] 32: Blood pressure measuring device; 32A: Main body; 32B: Cuff part;

[0190] 33: Server;

[0191] N: Network.

Claims

1. A blood pressure measuring device, characterized in that, The blood pressure measuring device has the following features: The feature acquisition unit acquires one or more features that are related to the estimation of human blood pressure values. The blood pressure calculation unit calculates the estimated blood pressure value based on the aforementioned characteristic quantity; The measured blood pressure value acquisition unit acquires the measured blood pressure value by a method different from the calculation performed by the blood pressure value calculation unit; The calibration determination unit determines whether the feature value obtained by the feature value acquisition unit deviates from the specified reference value, and if it determines that the feature value deviates, it decides to acquire the measured blood pressure value. and The calibration processing unit uses the measured blood pressure value to calibrate the algorithm for calculating the estimated blood pressure value implemented by the blood pressure calculation unit. The calibration processing unit, based on the difference between the measured blood pressure value obtained by the calibration determination unit and the estimated blood pressure value calculated using the characteristic quantity deviating from the reference value, and a predetermined threshold for comparison with the difference, changes the reference value to a value that determines a decrease in the frequency of obtaining the measured blood pressure value when the difference is below the predetermined threshold, and changes the reference value to a value that determines an increase in the frequency of obtaining the measured blood pressure value when the difference is greater than the predetermined threshold.

2. The blood pressure measuring device according to claim 1, characterized in that, If the difference is below the specified threshold, the calibration processing unit changes the reference value to a value that reduces the frequency of obtaining the measured blood pressure value. When the reference value is an upper limit threshold related to the feature quantity, the calibration processing unit increases the value of the reference value. When the reference value is a lower limit threshold related to the feature quantity, the calibration processing unit reduces the value of the reference value. When the reference value is a threshold value that defines the upper and lower limits of a numerical range related to the feature quantity, the calibration processing unit increases the upper limit threshold and / or decreases the lower limit threshold.

3. The blood pressure measuring device according to claim 1, characterized in that, If the difference is greater than the predetermined threshold, the calibration processing unit changes the reference value to a value that increases the frequency of obtaining the measured blood pressure value. When the reference value is an upper limit threshold related to the feature quantity, the calibration processing unit reduces the value of the reference value. When the reference value is a lower limit threshold related to the feature quantity, the calibration processing unit increases the value of the reference value. When the reference value is a threshold value that defines the upper and lower limits of a numerical range related to the feature quantity, the calibration processing unit reduces the upper limit threshold and / or increases the lower limit threshold.

4. The blood pressure measuring device according to any one of claims 1 to 3, characterized in that, The blood pressure measuring device also has an output unit. If the calibration determination unit decides to acquire the measured blood pressure value, the output unit outputs information indicating that the measured blood pressure value needs to be acquired.

5. The blood pressure measuring device according to any one of claims 1 to 3, characterized in that, The blood pressure measuring device also includes a blood pressure measuring unit for measuring the measured blood pressure value. When the calibration determination unit decides to acquire the measured blood pressure value, the measured blood pressure value acquisition unit acquires the measured blood pressure value by measuring the measured blood pressure value implemented by the blood pressure measurement unit.

6. The blood pressure measuring device according to any one of claims 1 to 3, characterized in that, The blood pressure measuring device also includes a blood pressure measuring unit and an operation input unit for measuring the measured blood pressure value. When the measured blood pressure value acquisition unit receives an input via the operation input unit instructing the measurement of the measured blood pressure value, it acquires the measured blood pressure value by performing the measurement of the measured blood pressure value implemented by the blood pressure measurement unit.

7. A blood pressure measurement system, characterized in that, The blood pressure measurement system has the following features: The feature acquisition unit acquires one or more features that are related to the estimation of human blood pressure values. The blood pressure calculation unit calculates the estimated blood pressure value based on the aforementioned characteristic quantity; The measured blood pressure value acquisition unit acquires the measured blood pressure value by a method different from the calculation performed by the blood pressure value calculation unit; The calibration determination unit determines whether the feature quantity obtained by the feature quantity acquisition unit deviates from the specified reference value, and if it is determined that it deviates, it decides to acquire the measured blood pressure value. and The calibration processing unit uses the measured blood pressure value to calibrate the calculation algorithm for the estimated blood pressure value implemented by the blood pressure value calculation unit. The calibration processing unit, based on the difference between the measured blood pressure value obtained through the determination of the calibration unit and the estimated blood pressure value calculated using the feature quantity deviating from the reference value, and a predetermined threshold for comparison with the difference, changes the reference value to a value that determines a decrease in the frequency of obtaining the measured blood pressure value when the difference is below the predetermined threshold; and changes the reference value to a value that determines an increase in the frequency of obtaining the measured blood pressure value when the difference is greater than the predetermined threshold.

8. The blood pressure measurement system according to claim 7, characterized in that, The blood pressure measurement system comprises: The measuring device includes at least one sensor for detecting the aforementioned characteristic quantity; and The information processing device includes at least the calibration processing unit.

9. The blood pressure measuring system according to claim 8, characterized in that, The measuring device also includes a blood pressure measuring unit for determining the measured blood pressure value.

10. The blood pressure measuring system according to claim 8 or 9, characterized in that, The measuring device is a wearable device that can be worn on the human body at all times.

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