Blood pressure measurement device, blood pressure measurement method, and program

Abstract

A blood pressure measuring device includes a cuff wound around a measurement site; a pressure detection unit that detects a cuff pressure in the cuff; a pressure control unit that controls the cuff pressure; a pulse wave information acquisition unit that acquires pulse wave information of a measurement subject in accordance with the cuff pressure; a first blood pressure calculation unit that calculates a first blood pressure of the measurement subject based on the pulse wave information; a second blood pressure calculation unit that calculates a second blood pressure of the measurement subject based on the pulse wave information acquired until the cuff pressure reaches a pressurization stop cuff pressure; a pressurization stop cuff pressure determination unit that determines a value of the pressurization stop cuff pressure based on a feature of the pulse wave information acquired at a cuff pressure lower than the pressurization stop cuff pressure; and a threshold reaching determination unit that determines whether the cuff pressure reaches a prescribed determination threshold related to a suspension of the first blood pressure calculation, and suspends the calculation of the first blood pressure by the first blood pressure calculation unit in a case where the cuff pressure reaches the prescribed determination threshold.

Description

Technical Field

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

[0002] In recent years, the use of measuring devices to measure personal health-related information such as blood pressure values, and to record and analyze the results for health management, has become increasingly common. As an example of the measuring device described above, a blood pressure monitor is used that measures blood pressure, including systolic blood pressure, based on pressure pulse waves obtained during the compression of a cuff worn on the subject's upper arm, wrist, or other measuring area (e.g., Patent Document 1, Patent Document 2, etc.).

[0003] Patent document 1 discloses a blood pressure monitor that allows users to select between two blood pressure measurement methods: a high-precision oscillometric method and a SPD method (Single Pulse Determination) method, which involves raising the cuff pressure to an arbitrary height and capturing the pulse wave signal in one or several beats to estimate the blood pressure value in a short time. This blood pressure monitor allows for faster cuff pressure control using the same device, reducing pain and discomfort during blood pressure measurement, and providing more accurate readings.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2003-250770

[0007] Patent Document 2: Japanese Patent Application Publication No. 03-280932 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] However, in the technology described in Patent Document 1, it is necessary to select which method to use for blood pressure measurement before the measurement begins. In addition, for users who already have low blood pressure, even blood pressure measurement based on the oscillometric method does not cause much pain or discomfort. Therefore, the disadvantages of not performing accurate measurements based on the oscillometric method can sometimes become more pronounced.

[0010] In view of the problems of the prior art as described above, the object of the present invention is to provide a technology that can reduce discomfort during blood pressure measurement and enable higher accuracy in blood pressure measurement, regardless of the blood pressure-related attributes of the user.

[0011] Solution for solving the problem

[0012] To solve the above problems, the present invention provides a blood pressure measuring device as follows:

[0013] A blood pressure measuring device, comprising:

[0014] The cuff is wrapped around the part being measured.

[0015] The pressure detection unit detects the cuff pressure inside the cuff.

[0016] The pressure control unit controls the pressure of the cuff;

[0017] The pulse wave information acquisition unit acquires the pulse wave information of the subject based on the cuff pressure.

[0018] The first blood pressure calculation unit calculates the first blood pressure of the subject based on the pulse wave information;

[0019] The second blood pressure calculation unit calculates the second blood pressure of the subject based on the pulse wave information obtained until the cuff pressure reaches the stop cuff pressure.

[0020] The compression stop cuff pressure determination unit determines the value of the compression stop cuff pressure based on characteristics of the pulse wave information acquired at a cuff pressure lower than the compression stop cuff pressure; and

[0021] The threshold determination unit determines whether the cuff pressure has reached a predetermined threshold related to the termination of the first blood pressure calculation.

[0022] When the cuff pressure reaches a predetermined threshold, the first blood pressure calculation unit stops calculating the first blood pressure.

[0023] It should be noted that the "pulse wave information" mentioned here can include not only the amplitude data of the pulse wave over time, but also the envelope of the pulse wave amplitude (hereinafter referred to as the envelope) obtained based on the amplitude data. Furthermore, the "compression stop cuff pressure" mentioned above can be set to a cuff pressure lower than the cuff pressure corresponding to the systolic blood pressure of the subject. Additionally, the "prescribed judgment threshold" can be set to a cuff pressure that does not cause pain to the user (e.g., 100 mmHg).

[0024] Furthermore, the aforementioned first blood pressure calculation unit can be configured to calculate blood pressure using the oscillometric method, but is not limited to this; it can also calculate blood pressure values ​​using the Korotkoff method (auscultation method), volume compensation method, etc.

[0025] Based on this configuration, for users with low blood pressure, such as those whose systolic blood pressure can be calculated using methods like oscillometric analysis before exceeding a predetermined threshold, blood pressure can be calculated with high precision. Furthermore, for users with high blood pressure, blood pressure can be calculated (estimated) by adjusting the cuff pressure until it equals the systolic blood pressure. Therefore, regardless of the user's blood pressure-related attributes, such as low or high blood pressure, discomfort during blood pressure measurement can be reduced, and higher accuracy in blood pressure measurement can be achieved.

[0026] Alternatively, the blood pressure measuring device may also have a display unit that displays the first blood pressure as the measured blood pressure value when the calculation of the first blood pressure is completed. Alternatively, the blood pressure measuring device may also have a display unit that displays the second blood pressure as the measured blood pressure value when the calculation of the first blood pressure is stopped.

[0027] Based on this configuration, when the first blood pressure can be calculated (i.e., when the blood pressure can be calculated using a high-precision measurement method until the cuff pressure, which serves as a judgment threshold, is reached), this value can be displayed as the measured blood pressure value. On the other hand, when the calculation process for the first blood pressure is stopped and the second blood pressure is calculated, this value can be displayed as the measured blood pressure value. Therefore, users can perform a measurement with minimal discomfort simply by starting a blood pressure measurement and can know a high-precision blood pressure value.

[0028] Alternatively, the blood pressure measuring device may also include: a third blood pressure calculation unit that calculates the subject's third blood pressure using the first blood pressure and the second blood pressure; and a display unit that displays the third blood pressure as the measured blood pressure value.

[0029] Even after the first blood pressure calculation is completed, the pressure control unit pressurizes the cuff until the cuff pressure reaches the pressure at which pressurization stops.

[0030] Here, "third blood pressure" can be set to, for example, the average of the first and second blood pressure values. Depending on the user's blood pressure-related attributes or the measurement environment, it is impossible to generalize which of the first and second blood pressure values ​​is more accurate. Therefore, by using the values ​​of both in this way, it is possible to prevent the use of a lower-precision value as the measured value.

[0031] Alternatively, the third blood pressure calculation unit may calculate the third blood pressure based on a weighted average of the first and second blood pressures according to predetermined parameters. Here, the "prescribed parameters" could be, for example, the timing for stopping cuff inflation, the level of the measured blood pressure, or past measurement values ​​(user attributes).

[0032] Furthermore, the present invention can also be considered as a method for measuring blood pressure as follows. That is,

[0033] A method for measuring blood pressure includes the following steps:

[0034] In blood pressure measuring devices

[0035] Detect the cuff pressure wrapped around the cuff of the part being measured;

[0036] Apply pressure to the cuff;

[0037] The pulse wave information of the subject is obtained based on the cuff pressure.

[0038] Perform the process of calculating the subject's first blood pressure based on the pulse wave information;

[0039] The process of calculating the subject's second blood pressure is performed based on the pulse wave information obtained until the cuff pressure reaches the stop cuff pressure.

[0040] The value of the stop-pressure cuff is determined based on the characteristics of the pulse wave information obtained at a cuff pressure lower than the stop-pressure cuff pressure.

[0041] The determination is made as to whether the cuff pressure has reached a predetermined threshold related to the termination of the calculation of the first blood pressure; and

[0042] If the cuff pressure reaches a predetermined threshold, the calculation of the first blood pressure is stopped.

[0043] Alternatively, the blood pressure measurement method may further include the following steps: If the calculation of the first blood pressure is completed, display the first blood pressure as the measured blood pressure value. Alternatively, if the calculation of the first blood pressure is stopped, display the second blood pressure as the measured blood pressure value.

[0044] Alternatively, the blood pressure measurement method may further include the following steps: calculating the subject's third blood pressure using the first blood pressure and the second blood pressure; and displaying the third blood pressure as the measured blood pressure value.

[0045] In the step of pressurizing the cuff, even after the first blood pressure calculation is completed, the cuff is pressurized until the cuff pressure reaches the pressurization stop cuff pressure.

[0046] Alternatively, in the step of calculating the third blood pressure, the third blood pressure may be calculated based on a weighted average of the first blood pressure and the second blood pressure according to prescribed parameters.

[0047] Furthermore, the present invention can also be considered as a program that causes a blood pressure measuring device to perform the above-described method, and a computer-readable recording medium that non-temporarily records such a program. Moreover, each of the above-described components and processes can be combined with each other to constitute the present invention, provided that no technical contradiction arises.

[0048] Invention Effects

[0049] According to the present invention, regardless of the blood pressure-related attributes of the user, discomfort during blood pressure measurement can be reduced, and higher accuracy of blood pressure measurement can be achieved. Attached Figure Description

[0050] Figure 1 This is a schematic diagram showing the hardware configuration of the blood pressure measuring device of Embodiment 1.

[0051] Figure 2 This is a block diagram illustrating an example of the functional modules of the blood pressure measuring device of Embodiment 1.

[0052] Figure 3 This is a first schematic diagram showing the relationship between the cuff pressure in a blood pressure measuring device and the envelope obtained from the pressure pulse wave.

[0053] Figure 4 This is a second schematic diagram showing the relationship between the cuff pressure in a blood pressure measuring device and the envelope obtained from the pressure pulse wave.

[0054] Figure 5 This is a flowchart illustrating the blood pressure measurement process in the blood pressure measuring device of Example 1.

[0055] Figure 6 This is a block diagram illustrating an example of the functional modules of the blood pressure measuring device of Embodiment 2.

[0056] Figure 7 This is a diagram illustrating the weighting related to the averaging process performed on the third blood pressure calculation unit in Example 2.

[0057] Figure 8 This is a flowchart illustrating the blood pressure measurement process in the blood pressure measuring device of Example 2. Detailed Implementation

[0058] <Example 1>

[0059] Hereinafter, specific embodiments of the present invention will be described based on the accompanying drawings. Unless otherwise specified, the dimensions, materials, shapes, and relative arrangements of the constituent components described in this embodiment are not intended to limit the scope of the invention.

[0060] (Device configuration)

[0061] Figure 1 This is a schematic diagram of the hardware configuration of the blood pressure measuring device 1 in this embodiment. Figure 1 As shown, the blood pressure measuring device 1 has a cuff 11, a pressure sensor 12, a pressurizing pump 13, an exhaust valve 14, an air tube 15, an oscillation circuit 21, a pump drive circuit 22, a valve drive circuit 23, a power supply 24, a display 25, an operation switch 26, a memory 27, and a CPU (Central Processing Unit) 100 as its hardware components.

[0062] The cuff 11 includes an air bag 11a containing air. Furthermore, a pressure sensor 12 detects the pressure (hereinafter referred to as "cuff pressure") within the air bag 11a of the cuff 11 via an air tube 15. Additionally, a pressurization pump 13 supplies air to the air bag 11a via the air tube 15. Furthermore, an exhaust valve 14 is a valve that opens and closes to maintain the pressure within the air bag 11a or to expel air from the air bag 11a.

[0063] CPU100 is an example of an arithmetic processing unit used to control various parts of the device. Furthermore, memory 27 includes main storage devices such as RAM (Random Access Memory) and auxiliary storage devices such as flash memory, storing data such as programs executed for blood pressure measurement processing, cuff pressure, pressure pulse wave, and blood pressure measurement results.

[0064] The display 25 is an example of a display device that displays various information such as blood pressure measurement results; for example, an LCD (Liquid Crystal Display) can be used. Furthermore, the operation switch 26 is an example of an input device used to input various instructions related to the operation of the device, including the blood pressure measurement. It should be noted that a touch panel display can also be used as both the display 25 and the operation switch 26. Additionally, the power supply 24, which supplies power to various parts of the device such as the CPU, can be supplied with power via a wired connection from a power outlet, or it can be a battery.

[0065] The oscillation circuit 21 outputs a signal with an oscillation frequency corresponding to the output value of the pressure sensor 12 to the CPU 100. The pump drive circuit 22 controls the drive of the pressurization pump 13 based on the control signal output from the CPU 100. The valve drive circuit 23 controls the opening and closing of the exhaust valve 14 based on the control signal output from the CPU 100.

[0066] Figure 2 This is a functional block diagram showing the functional modules of the CPU 100 of the blood pressure measuring device 1. For example... Figure 2As shown, the CPU100 includes functional modules such as a pressure detection unit 110, a pressure control unit 120, a first blood pressure calculation unit 130, a threshold reaching determination unit 140, a second blood pressure calculation unit 150, and a pressure determination unit 160 for stopping the pressurization cuff.

[0067] The output signal of the oscillation circuit 21 is input to the pressure detection unit 110. The pressure detection unit 110 detects the oscillation frequency of the input signal and converts the detected oscillation frequency into a pressure value signal. The pressure detection unit 110 includes: an HPF unit 111, which extracts and outputs a pressure pulse wave signal by performing HPF (High Pass Filter) processing on the pressure value signal; and an LPF unit 112, which extracts and outputs a cuff pressure signal by performing LPF (Low Pass Filter) processing on the pressure value signal. The pressure pulse wave signal detected sequentially by the HPF unit 111 of the pressure detection unit 110 and the cuff pressure signal representing the cuff pressure detected sequentially by the LPF unit 112 are stored in a predetermined area of ​​the memory 27 and transmitted to the smartphone 50 via the communication IF 28. It should be noted that the HPF unit 111 corresponds to the pulse wave information acquisition unit of the present invention.

[0068] Figure 3 and Figure 4 This is a schematic graph showing the relationship between the cuff pressure detected by the pressure sensing unit 110 and the pressure pulse wave (more specifically, the envelope obtained based on the time-varying data of the amplitude of the pressure pulse wave). Generally speaking, as... Figure 3 As shown, the lowest blood pressure (DIA, diastolic blood pressure, DBP) and highest blood pressure (SYS, systolic blood pressure, SBP) are calculated as cuff pressures corresponding to specific variation patterns of the pressure pulse wave.

[0069] The pressure control unit 120 controls the cuff pressure of the cuff 11 by controlling the operation of the pump drive circuit 22 and the valve drive circuit 23.

[0070] The first blood pressure calculation unit 130 inputs a pressure pulse wave signal extracted by the HPF unit 111 of the pressure detection unit 110, and processes the input pressure pulse wave signal according to the oscillometric method to calculate the minimum blood pressure and the maximum blood pressure. The oscillometric method is a well-known technique, therefore repeated explanations are omitted.

[0071] The threshold determination unit 140 determines whether the cuff pressure obtained from the LPF unit 112 of the pressure detection unit 110 exceeds the threshold used to switch the blood pressure measurement from the method based on the first blood pressure calculation unit 130 to the method based on the second blood pressure calculation unit 150 (described later). The threshold can be set to a value at which the subject will not feel pain (discomfort) due to pressure, for example, it can be set to 100 mmHg.

[0072] The second blood pressure calculation unit 150 does not calculate blood pressure based on oscillometric methods, but rather calculates an estimated blood pressure value based on pressure pulse wave data acquired during the period until the cuff pressure reaches a level lower than the cuff pressure corresponding to the subject's systolic blood pressure. For example... Figure 3 and Figure 4 As shown, DIA can be detected at a cuff pressure earlier than the peak of the envelope, i.e., at a cuff pressure lower than the cuff pressure corresponding to the peak of the envelope. Furthermore, the peak of the envelope is located earlier than the SYS (systolic blood pressure), meaning the cuff pressure corresponding to the peak is lower than the cuff pressure corresponding to the SYS. Therefore, considering these points, the cuff pressure at which the peak of the envelope is lower than the cuff pressure corresponding to the subject's systolic blood pressure can also be defined as the cuff pressure at which the peak of the envelope is reached.

[0073] After acquiring the pressure pulse wave data required for blood pressure calculation based solely on the second blood pressure calculation unit 150, the pressure-stop cuff pressure determination unit 160 determines the cuff pressure (hereinafter referred to as the pressure-stop cuff pressure) for applying pressure to the cuff 11 as quickly as possible. Here, if the second blood pressure calculation unit 150 calculates blood pressure based on pressure pulse wave data acquired up to the cuff pressure corresponding to the peak value of the envelope, then... Figure 4 As shown, the stop pressure of the compression cuff is a cuff pressure that is (slightly) higher than the cuff pressure corresponding to the peak value of the envelope. It should be noted that the stop pressure of the compression cuff can also be determined, for example, by calculating the DBP and using it as a reference. Specifically, this cuff pressure can be determined, for example, by the following method.

[0074] As indicators derived from pressure pulse wave information, as shown in Patent Document 2, indicators such as RAV, WID, and DFN are known. These are indicators calculated per beat of the pressure pulse wave. RAV, WID, and DFN represent the area, width, and slope of a pulse wave per beat, respectively. Specifically, RAV is obtained by normalizing the pulse wave area per beat to the amplitude, and is represented by (pulse wave area / pulse wave amplitude per beat) × 100. WID is obtained by normalizing the waveform width, which is the time width from the maximum amplitude to the threshold, to the pulse wave period, and is represented by (waveform width / pulse wave period) × 100. DFN is obtained by normalizing the minimum value of the first derivative of the pressure pulse wave to the pulse wave amplitude, and is represented by (minimum value of the first derivative of the pulse wave starting from 0 / pulse wave amplitude of the first derivative of the pulse wave) × 100.

[0075] Furthermore, when the cuff pressure that will become DBP is set as Pd, it is expressed as a function of RAV, WID, and DFN, such as Pd = f(RAV, WID, DFN). Here, Pd is expressed as a function of these three indicators, but it can also be expressed as any one or any two indicators. The form of the function f is not particularly limited, but by calculating these indicators for each beat of the pressure pulse wave obtained by the HPF unit 111, it is possible to determine whether the cuff pressure has reached DBP.

[0076] When the stop pressure of the compression cuff is set to P1, the relationship between the cuff pressure value and DBP is expressed by a prescribed formula, such as P1 = g(Pd). It should be noted that the form of the function g is not particularly limited. Furthermore, if pressure pulse wave data up to the peak of the envelope is used in the blood pressure estimation based on the second blood pressure calculation unit 150, the stop pressure of the compression cuff can be set to a slightly higher cuff pressure than the cuff pressure corresponding to the peak of the envelope.

[0077] (Blood pressure measurement and processing)

[0078] Next, based on Figure 5 The process of blood pressure measurement and processing performed by the blood pressure measuring device in this embodiment will be described. Figure 5 This is a flowchart illustrating the process of blood pressure measurement performed by the blood pressure measuring device 1 in this embodiment.

[0079] It should be noted that, prior to the start of the process described below, the procedure is performed with the subject wrapping the cuff 11 around the area to be measured (e.g., the upper arm), and the prescribed settings are made by operating the switch 26, indicating that blood pressure measurement is to begin. Furthermore, upon receiving the indication to begin blood pressure measurement, the blood pressure measuring device 1 performs the prescribed initialization, such as opening the exhaust valve 14 and setting the cuff pressure to atmospheric pressure (initial pressure).

[0080] When blood pressure measurement begins in the blood pressure measuring device 1, the pressure control unit 120 begins pressure control of the cuff 11 (S101). During pressure control, the HPF unit 111 of the pressure detection unit 110 acquires the pressure pulse wave (S102), and the LPF unit 112 acquires the cuff pressure. Next, the threshold determination unit 140 determines whether the acquired cuff pressure exceeds a threshold (e.g., 100 mmHg) (S103).

[0081] If, in step S103, it is determined that the cuff pressure does not exceed the threshold, the first blood pressure calculation unit 130 performs a process of calculating the blood pressure value using an oscillometric method based on the pressure pulse wave acquired over time (S104). Then, the CPU 100 determines whether the calculation of the blood pressure value based on the first blood pressure calculation unit 130 (i.e., based on the oscillometric method) is complete (S105). Here, if it is determined that the blood pressure calculation based on the first blood pressure calculation unit 130 is complete, the process proceeds to step S108. On the other hand, if it is determined in step S105 that the blood pressure calculation based on the first blood pressure calculation unit 130 is incomplete, the process returns to step S102, and subsequent processing is repeated. It should be noted that, hereinafter, the blood pressure value calculated by the first blood pressure calculation unit 130 will also be referred to as the first calculated value. The first calculated value corresponds to the first blood pressure of the present invention.

[0082] On the other hand, if it is determined in step S103 that the cuff pressure exceeds the threshold, the pressure stop cuff pressure determination unit 160 performs a process to determine the pressure stop cuff pressure (S106), and then determines whether the cuff pressure obtained from the LPF unit 112 reaches the pressure stop cuff pressure determined in step S106 (S107). It should be noted that the determination of the pressure stop cuff pressure is as described above.

[0083] If it is determined in step S107 that the cuff pressure has not yet reached the stop pressure for pressurization, the process returns to step S102 and repeats the subsequent processing. On the other hand, if it is determined in step S107 that the cuff pressure has reached the stop pressure for pressurization, the process proceeds to step S108.

[0084] In step S108, the pressure application of the cuff 11 is stopped under the control of the pressure control unit 120 (S108). Next, the CPU 100 performs a process to determine whether the calculation of the blood pressure value based on the first blood pressure calculation unit 130 is complete (S109). Here, if it is determined that the calculation of the blood pressure value based on the first blood pressure calculation unit 130 is complete, the CPU 100 displays the calculated blood pressure value as a measured value on the display 25 (S111), records the measurement result including the blood pressure value in a designated area of ​​the memory 27 of the blood pressure measuring device 1 (S112), and ends the series of blood pressure measurement processes.

[0085] On the other hand, if it is determined in step S109 that the calculation of the blood pressure value based on the first blood pressure calculation unit 130 is not completed, the second blood pressure calculation unit 150 performs a process to estimate the blood pressure value based on the pressure pulse wave data obtained up to the pressure of the compression stop cuff (S110). It should be noted that, hereinafter, the blood pressure value calculated by the second blood pressure calculation unit 150 will also be referred to as the second calculated value. The second calculated value is equivalent to the second blood pressure of the present invention. Furthermore, when the blood pressure value is calculated by the second blood pressure calculation unit 150, the CPU 100 displays the calculated blood pressure value as a measured value on the display 25 (S111), records the measurement result including the blood pressure value in a designated area of ​​the memory 27 of the blood pressure measuring device 1 (S112), and ends the series of blood pressure measurement processes.

[0086] According to the blood pressure measuring device 1 described above, if the blood pressure calculation based on the oscillometric method is completed until the cuff pressure of the inflated cuff 11 exceeds a predetermined threshold, the blood pressure calculated using the oscillometric method with high precision can be used as the measured value. On the other hand, if the blood pressure measurement based on the oscillometric method is not completed even if the cuff pressure exceeds the threshold, the inflating of the cuff 11 is stopped before reaching the cuff pressure corresponding to the systolic blood pressure, and the blood pressure is estimated using the pressure pulse wave data up to the point where the inflating is stopped. This allows for blood pressure measurement with reduced discomfort for the subject. In other words, the subject does not need to select which method to use for blood pressure measurement beforehand; as long as the blood pressure measurement begins, the pain / discomfort caused by the compression of the cuff 11 is reduced, and blood pressure calculation based on a more precise method can be performed automatically.

[0087] <Example 2>

[0088] Next, based on Figures 6 to 8 The second embodiment of the present invention will now be described. The hardware configuration of the blood pressure measuring device 2 in this embodiment is the same as that in Embodiment 1. Therefore, regarding the hardware configuration and other components common to Embodiment 1, the same reference numerals as in Embodiment 1 will be used and repeated descriptions will be omitted.

[0089] like Figure 6 As shown in the functional block diagram, the blood pressure measuring device 2 of this embodiment differs from that of Embodiment 1 in that it includes a third blood pressure calculation unit 170 as a functional module of the CPU 100A. The third blood pressure calculation unit 170 uses the blood pressure value (first calculated value) calculated by the first blood pressure calculation unit 130 and the blood pressure value (second calculated value) calculated by the second blood pressure calculation unit 150 to calculate the blood pressure of the subject.

[0090] Specifically, the third blood pressure calculation unit 170 calculates the average of the first and second calculated values ​​after both the first and second calculated values ​​have been calculated. More specifically, the third blood pressure calculation unit 170 calculates the average based on a weighted average of the first and second calculated values ​​according to attributes related to the blood pressure of the subject (hypertension, hypotension, standard). Figure 7 This is a table illustrating an example of the average value calculated by the third blood pressure calculation unit 170.

[0091] like Figure 7 As shown, for subjects with low blood pressure, the weight of the first calculated value is increased; conversely, for subjects with high blood pressure, the weight of the second calculated value is increased, and the average of the two calculated values ​​is calculated. It should be noted that the degree to which weights can be appropriately set, and the parameters that serve as the basis for weighting, are not limited to, for example... Figure 7 The example shown.

[0092] Depending on the attributes related to the subject's blood pressure or the measurement environment, there may be cases where the second calculated value is a more accurate measurement value than the first calculated value (especially in cases where a learned inference model is used as the second blood pressure calculation unit). Therefore, when either value can be calculated, the third blood pressure calculation unit 170 averages the two values ​​using the method described above, thereby preventing the use of a lower-precision value as the measurement value.

[0093] Next, based on Figure 8 The procedure for blood pressure measurement and processing in this embodiment will be explained. Figure 8 This is a flowchart illustrating the blood pressure measurement process in this embodiment. The overall process for blood pressure measurement in this embodiment is largely the same as in Embodiment 1.

[0094] First, when blood pressure measurement begins in the blood pressure measuring device 2, the pressure control unit 120 begins pressure control of the cuff 11 (S201). During pressure control, the HPF unit 111 of the pressure detection unit 110 acquires the pressure pulse wave (S202), and the LPF unit 112 acquires the cuff pressure. Next, the threshold determination unit 140 determines whether the acquired cuff pressure exceeds a threshold (e.g., 100 mmHg) (S203).

[0095] If, in step S203, it is determined that the cuff pressure has not exceeded the threshold, the first blood pressure calculation unit 130 performs a process of calculating the blood pressure value using an oscillometric method based on the pressure pulse wave acquired over time (S204). Then, the CPU 100A determines whether the calculation of the blood pressure value based on the first blood pressure calculation unit 130 (i.e., based on the oscillometric method) is complete (S205). Here, if it is determined that the blood pressure calculation based on the first blood pressure calculation unit 130 is incomplete, the process returns to step S202 and repeats the subsequent processing.

[0096] On the other hand, if it is determined in step S205 that the blood pressure calculation based on the first blood pressure calculation unit 130 is complete, unlike in Embodiment 1, the process proceeds to step S206. That is, in this embodiment, even if the blood pressure calculation based on the first blood pressure calculation unit 130 is complete, the cuff pressure is not immediately stopped based on this condition. However, if the blood pressure calculation based on the first blood pressure calculation unit 130 is complete, such as Figure 3 , Figure 4 As shown, it is highly likely to obtain data on almost all pressure pulse waves that form the envelope, typically reaching the stop cuff pressure without intervals.

[0097] It should be noted that if it is determined in step S203 that the cuff pressure exceeds the threshold, the pressure stop cuff pressure determination unit 160 performs the process of determining the pressure stop cuff pressure (S206), and then determines whether the cuff pressure obtained from the LPF unit 112 reaches the pressure stop cuff pressure determined in step S206 (S207).

[0098] If it is determined in step S207 that the cuff pressure has not yet reached the stop pressure for pressurization, the process returns to step S202 and repeats the subsequent processing. On the other hand, if it is determined in step S207 that the cuff pressure has reached the stop pressure for pressurization, the process proceeds to step S208.

[0099] In step S208, the pressure of the cuff 11 is stopped by the control of the pressure control unit 120 (S208). Next, the second blood pressure calculation unit 150 performs a process to calculate (estimate) the blood pressure value based on the pressure pulse wave data acquired up to the point where the pressure of the cuff stops (S209). When the calculation of the blood pressure value based on the second blood pressure calculation unit 150 is completed, the CPU 100A determines whether both the first calculated value and the second calculated value have been calculated (S210).

[0100] If, in step S210, it is determined that both the first calculated value and the second calculated value have been calculated (if it is "Yes" in step S210), the third blood pressure calculation unit 170 uses the first calculated value and the second calculated value to calculate the average value (S211). It should be noted that, hereinafter, the value calculated by the third blood pressure calculation unit 170 in step S211 will also be referred to as the third calculated value. The third calculated value corresponds to the third blood pressure of the present invention. Details regarding the calculation process based on the third blood pressure calculation unit 170 are as described above.

[0101] When the third calculated value is obtained, the CPU100A displays the third calculated value as the measured value on the display 25 (S212), records the measurement result containing the measured value in a designated area of ​​the memory 27 of the blood pressure measuring device 2 (S213), and ends a series of blood pressure measurement processes.

[0102] On the other hand, if it is determined in step S210 that only the second calculated value has been calculated (if it is No in step S210), and if it is determined that the calculation of the blood pressure value based on the first blood pressure calculation unit 130 has not been completed, the CPU 100A displays the second calculated value as the measured value on the display 25 (S212), records the measurement result including the measured value in a predetermined area of ​​the memory 27 of the blood pressure measuring device 2 (S213), and ends a series of blood pressure measurement processes.

[0103] According to the blood pressure measuring device 2 of this embodiment described above, by averaging the first and second calculated values ​​with appropriate weights, it is possible to prevent the use of lower-precision values ​​as measured values. That is, the overall accuracy of the calculated blood pressure value can be improved.

[0104] <Other>

[0105] The foregoing examples are merely illustrative of the invention, and the invention is not limited to the specific embodiments described above. Various modifications and combinations can be made within the scope of the invention's technical concept. For example, in various embodiments, the first blood pressure calculation unit 130 is exemplified to perform blood pressure calculation using the oscillometric method, but blood pressure calculation can also be performed using other methods such as auscultation, volume compensation, etc.

[0106] Furthermore, for the second blood pressure calculation unit 150, the blood pressure of the subject can be estimated based on the pulse wave information obtained until the pressure of the cuff is reduced to stop. For example, the second blood pressure calculation unit 150 can also be set as an inference model that has been learned by machine learning.

[0107] Furthermore, the cuff pressure for stopping the inflation is determined with the peak value of the envelope as the target in the examples above, but it is not limited to this. Any cuff pressure at any point in time that corresponds to the systolic blood pressure of the subject can be used. Alternatively, the characteristics of the envelope slope (points where the upward or downward gradient becomes steeper, or points where the gradient stabilizes) can be used as markers, and the corresponding cuff pressure can be taken as the inflation stopping cuff pressure.

[0108] Explanation of reference numerals in the attached figures

[0109] 1, 2: Blood pressure measuring device;

[0110] 11: Cuffs;

[0111] 15: Air pipe;

[0112] 100, 100A: CPU;

[0113] 110: Pressure Testing Department;

[0114] 120: Pressure Control Unit;

[0115] 130: First Blood Pressure Calculation Department;

[0116] 140: Threshold reached in the decision-making section;

[0117] 150: Second blood pressure calculation unit;

[0118] 160: Pressure stop cuff pressure determination unit;

[0119] 170: Third Blood Pressure Calculation Department.

Claims

1. A blood pressure measuring device, comprising: The cuff is wrapped around the part being measured. The pressure detection unit detects the cuff pressure inside the cuff. The pressure control unit controls the pressure of the cuff; The pulse wave information acquisition unit acquires the pulse wave information of the subject based on the cuff pressure. The first blood pressure calculation unit calculates the first blood pressure of the subject based on the pulse wave information; The second blood pressure calculation unit calculates the second blood pressure of the subject based on the pulse wave information obtained until the cuff pressure reaches the stop cuff pressure. The pressure stop cuff pressure determination unit determines the value of the pressure stop cuff pressure based on the characteristics of the pulse wave information obtained at a cuff pressure lower than the pressure stop cuff pressure. as well as The threshold determination unit determines whether the cuff pressure has reached a predetermined threshold related to the termination of the first blood pressure calculation. When the cuff pressure reaches a predetermined threshold, the first blood pressure calculation unit stops calculating the first blood pressure.

2. The blood pressure measuring device according to claim 1, wherein, The blood pressure measuring device also has a display unit, which displays the first blood pressure as the measured blood pressure value after the calculation of the first blood pressure is completed.

3. The blood pressure measuring device according to claim 1, wherein, The blood pressure measuring device also has a display unit, which displays the second blood pressure as the measured blood pressure value when the calculation of the first blood pressure is stopped.

4. The blood pressure measuring device according to claim 1, wherein, The blood pressure measuring device also has: The third blood pressure calculation unit uses the first blood pressure and the second blood pressure to calculate the third blood pressure of the subject. as well as The display unit shows the third blood pressure reading as the measured blood pressure value. Even after the first blood pressure calculation is completed, the pressure control unit pressurizes the cuff until the cuff pressure reaches the pressure at which pressurization stops.

5. The blood pressure measuring device according to claim 4, wherein, The third blood pressure calculation unit calculates the third blood pressure based on a weighted average of the first and second blood pressures according to specified parameters.

6. A method for measuring blood pressure, comprising the following steps: In blood pressure measuring devices Detect the cuff pressure wrapped around the cuff of the part being measured; Apply pressure to the cuff; The pulse wave information of the subject is obtained based on the cuff pressure. Perform the process of calculating the subject's first blood pressure based on the pulse wave information; The process of calculating the subject's second blood pressure is performed based on the pulse wave information obtained until the cuff pressure reaches the stop cuff pressure. The value of the stop-pressure cuff is determined based on the characteristics of the pulse wave information obtained at a cuff pressure lower than the stop-pressure cuff pressure. A determination is made as to whether the cuff pressure has reached a predetermined threshold related to the termination of the calculation of the first blood pressure. as well as If the cuff pressure reaches a predetermined threshold, the calculation of the first blood pressure is stopped.

7. The blood pressure measurement method according to claim 6, wherein, The blood pressure measurement method further includes the following steps: after the calculation of the first blood pressure is completed, the first blood pressure is displayed as the measured blood pressure value.

8. The blood pressure measurement method according to claim 6, wherein, The blood pressure measurement method further includes the following steps: if the calculation of the first blood pressure is stopped, the second blood pressure is displayed as the measured blood pressure value.

9. The blood pressure measurement method according to claim 6, wherein, The blood pressure measurement method also includes the following steps: The third blood pressure of the subject was calculated using the first and second blood pressure readings; and The third blood pressure reading is displayed as the measured blood pressure value. In the step of pressurizing the cuff, even after the first blood pressure calculation is completed, the cuff is pressurized until the cuff pressure reaches the pressurization stop cuff pressure.

10. The blood pressure measurement method according to claim 9, wherein, In the step of calculating the third blood pressure, the third blood pressure is calculated based on a weighted average of the first blood pressure and the second blood pressure according to specified parameters.

11. A procedure for causing a blood pressure measuring device to perform the steps of the blood pressure measuring method according to any one of claims 6 to 10.

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