Sphygmomanometer apparatus, sphygmomanometry method and program

Abstract

To provide a technique capable of reducing discomfort during measurement of the blood pressure and measuring the blood pressure with a higher degree of precision.SOLUTION: A sphygmomanometer apparatus includes: a cuff to be wound around a measured part; a pressure detection unit for detecting a cuff pressure within the cuff; a pressure controlling unit for controlling the cuff pressure; a pulse wave acquisition unit for acquiring pulse wave information of a measured person from the cuff pressure; a first blood pressure calculation unit for calculating the measured person's first blood pressure on the basis of the pulse wave information; a second blood pressure calculation unit for calculating the measured person's second blood pressure on the basis of the pulse wave information acquired until the cuff pressure reaches a pressurization stop cuff pressure; a stop cuff pressure determination unit for determining the value of the stop cuff pressure on the basis of characteristics of pulse wave information acquired at a cuff pressure lower than the pressurization stop cuff pressure; and a threshold attainment determination unit for determining whether the cuff pressure reaches a prescribed determination threshold relating to the stop of calculation of the first blood pressure. When the cuff pressure reaches the prescribed determination threshold, the first blood pressure calculation unit stops calculating the first blood pressure.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a blood pressure measurement device, a blood pressure measurement method, and a program. [Background technology]

[0002] In recent years, health management has become commonplace by measuring information about an individual's physical and health, such as blood pressure values, using a measuring device and recording and analyzing the measurement results. One example of such a measuring device is a sphygmomanometer, which measures blood pressure, including systolic blood pressure, based on a pressure pulse wave acquired in the process of inflating a cuff attached to the subject's upper arm, wrist, or other part of the body to be measured (see, for example, Patent Document 1 and Patent Document 2).

[0003] Patent Document 1 proposes a blood pressure monitor that allows a user to select, by operating a switch before starting measurement, either a blood pressure measurement method using the oscillometric method, which has high measurement accuracy, or a single pulse determination (SPD) method, which estimates blood pressure values ​​in a short time by increasing and maintaining the cuff pressure to a desired level and capturing pulse wave signals for one or several beats. With this blood pressure monitor, cuff inflation stops in a shorter time, making it possible to achieve both blood pressure measurement that reduces pain and discomfort and more accurate blood pressure measurement, all with the same device. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-250770 [Patent Document 2] Japanese Patent Application Publication No. 03-280932 Summary of the Invention [Problem to be solved by the invention]

[0005] However, with the technology described in Patent Document 1, it is necessary to select which method to use for blood pressure measurement before starting measurement. Also, for users with low blood pressure, blood pressure measurement using the oscillometric method does not cause much pain or discomfort, so there are cases where the disadvantages of not performing accurate measurement using the oscillometric method outweigh the benefits.

[0006] In view of the problems with the conventional technology as described above, the present invention aims to provide technology that reduces discomfort during blood pressure measurement and enables more accurate blood pressure measurement, regardless of the user's blood pressure-related attributes. [Means for solving the problem]

[0007] In order to solve the above problems, one aspect of the present invention is a blood pressure measuring device as follows: a cuff that is wrapped around the part to be measured; 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 acquiring unit that acquires pulse wave information of the subject from the cuff pressure; a first blood pressure calculation unit that calculates a first blood pressure of the subject based on the pulse wave information; a second blood pressure calculation unit that calculates a second blood pressure of the subject based on the pulse wave information acquired before the cuff pressure reaches an inflation stop cuff pressure; a stop cuff pressure determination unit that determines the value of the inflation stop cuff pressure based on characteristics of the pulse wave information acquired at the cuff pressure lower than the inflation stop cuff pressure; a threshold reaching determination unit that determines whether the cuff pressure has reached a predetermined determination threshold related to the termination of the first blood pressure calculation, When the cuff pressure reaches a predetermined determination threshold, the first blood pressure calculation unit stops calculating the first blood pressure. A blood pressure measuring device.

[0008] The "pulse wave information" referred to here may include not only pulse wave amplitude data over time but also the envelope of the pulse wave amplitude (hereinafter simply referred to as the envelope) obtained based on the data. The "inflation stop cuff pressure" referred to above may be a cuff pressure lower than the cuff pressure corresponding to the subject's systolic blood pressure. The "predetermined judgment threshold" may be a cuff pressure (e.g., 100 mmHg) that does not cause pain to the user.

[0009] Furthermore, the first blood pressure calculation unit can be configured to calculate blood pressure by, for example, the oscillometric method, but is not limited to this, and blood pressure values ​​may also be calculated by the Korotkoff method (auscultation method) or the volume compensation method.

[0010] With this configuration, for low blood pressure users whose systolic blood pressure can be calculated using a method such as the oscillometric method before the blood pressure exceeds a predetermined threshold, the blood pressure can be calculated with a high accuracy, and for high blood pressure users, the blood pressure can be calculated (estimated) without increasing the cuff pressure until it becomes equal to the systolic blood pressure. Therefore, regardless of the user's blood pressure-related attributes, such as low blood pressure or high blood pressure, it is possible to reduce discomfort during blood pressure measurement and perform blood pressure measurement with higher accuracy.

[0011] The blood pressure measurement device may further include a display unit that displays the first blood pressure as a measured blood pressure value when calculation of the first blood pressure is completed, or that displays the second blood pressure as a measured blood pressure value when calculation of the first blood pressure is stopped.

[0012] With this configuration, if the first blood pressure can be calculated (i.e., if the blood pressure can be calculated using an accurate measurement method before reaching the cuff pressure that is the judgment threshold), that value can be displayed as the measured blood pressure value.On the other hand, if the calculation process for the first blood pressure is stopped and the second blood pressure is calculated, that value can be displayed as the measured blood pressure value.Therefore, the user can simply start blood pressure measurement, measure using the measurement method that causes the least discomfort, and know the most accurate blood pressure value.

[0013] The blood pressure measurement device further includes a third blood pressure calculation unit that calculates a third blood pressure of the subject using the first blood pressure and the second blood pressure, and a display unit that displays the third blood pressure as a measured blood pressure value, The pressure control unit may inflate the cuff until the cuff pressure reaches the inflation stop cuff pressure even after the calculation of the first blood pressure is completed.

[0014] Here, the "third blood pressure" can be, for example, the average value of the first blood pressure and the second blood pressure. Because it is not possible to say in general which of the first blood pressure and the second blood pressure is the more accurate blood pressure value depending on the attributes of the user related to blood pressure or the measurement environment, using both values ​​in this way makes it possible to prevent a less accurate value from being taken as the measured value.

[0015] The third blood pressure calculation unit may also calculate the third blood pressure after weighting the first blood pressure and the second blood pressure according to a predetermined parameter. Here, the "predetermined parameter" may be, for example, the timing at which cuff inflation was stopped, the level of the measured blood pressure, or past measured values ​​(user attributes).

[0016] The present invention can also be understood as a blood pressure measurement method as follows: In the blood pressure measuring device, detecting a cuff pressure in a cuff wrapped around the measurement target part; Increasing the cuff pressure; acquiring pulse wave information of the subject from the cuff pressure; executing a process of calculating a first blood pressure of the subject based on the pulse wave information; executing a process of calculating a second blood pressure of the subject based on the pulse wave information acquired before the cuff pressure reaches an inflation stop cuff pressure; determining a value of the inflation stop cuff pressure based on characteristics of the pulse wave information acquired at a cuff pressure lower than the inflation stop cuff pressure; determining whether the cuff pressure has reached a predetermined determination threshold for stopping calculation of the first blood pressure; and stopping the calculation of the first blood pressure when the cuff pressure reaches a predetermined determination threshold. A method for measuring blood pressure.

[0017] The blood pressure measurement method may further include a step of displaying the first blood pressure as a measured blood pressure value when calculation of the first blood pressure is completed, and displaying the second blood pressure as a measured blood pressure value when calculation of the first blood pressure is stopped.

[0018] The blood pressure measurement method further includes a step of calculating a third blood pressure of the subject using the first blood pressure and the second blood pressure, and a step of displaying the third blood pressure as a measured blood pressure value, In the step of increasing the cuff pressure, the cuff may be inflated until the cuff pressure reaches the inflation stop cuff pressure even after the calculation of the first blood pressure has been completed.

[0019] Furthermore, in the step of calculating the third blood pressure, the third blood pressure may be calculated after weighting the first blood pressure and the second blood pressure in accordance with a predetermined parameter.

[0020] The present invention can also be understood as a program for causing a blood pressure measurement device to execute the above-described method, or a computer-readable recording medium on which such a program is non-temporarily recorded. Furthermore, the above-described configurations and processes can be combined to constitute the present invention as long as no technical contradiction occurs. [Effects of the Invention]

[0021] According to the present invention, it is possible to reduce discomfort during blood pressure measurement and perform more accurate blood pressure measurement, regardless of the user's blood pressure-related attributes. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1 is a schematic diagram illustrating a hardware configuration of a blood pressure measurement device according to a first embodiment. [Figure 2] FIG. 2 is a block diagram illustrating an example of a functional module included in the blood pressure measurement device according to the first embodiment. [Figure 3] FIG. 3 is a first schematic diagram showing the relationship between the cuff pressure in the blood pressure measurement device and the envelope obtained from the pressure pulse wave. [Figure 4] FIG. 4 is a second schematic diagram showing the relationship between the cuff pressure in the blood pressure measurement device and the envelope obtained from the pressure pulse wave. [Figure 5] FIG. 5 is a flowchart illustrating the flow of a blood pressure measurement process in the blood pressure measurement device according to the first embodiment. [Figure 6] FIG. 6 is a block diagram illustrating an example of a functional module included in the blood pressure measurement device according to the second embodiment. [Figure 7] FIG. 7 is a diagram illustrating weighting in the averaging process performed by the third blood pressure calculation unit according to the second embodiment. [Figure 8] FIG. 8 is a flowchart illustrating the flow of a blood pressure measurement process in the blood pressure measurement device according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0023] Example 1 Specific examples of the present invention will be described below with reference to the drawings. However, unless otherwise specified, the dimensions, materials, shapes, relative positions, etc. of the components described in these examples are not intended to limit the scope of the present invention.

[0024] (Device configuration) Fig. 1 is a schematic diagram of the hardware configuration of a blood pressure measurement device 1 according to this embodiment. As shown in Fig. 1, the blood pressure measurement device 1 includes, as its hardware configuration, a cuff 11, a pressure sensor 12, a pressure 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.

[0025] Cuff 11 includes air bag 11a containing air. Pressure sensor 12 detects the pressure inside air bag 11a of cuff 11 (hereinafter referred to as "cuff pressure") via air tube 15. Pressure pump 13 supplies air to air bag 11a via air tube 15. Exhaust valve 14 is a valve that opens and closes to maintain the pressure inside air bag 11a or to exhaust air from air bag 11a.

[0026] CPU 100 is an example of a processing unit for controlling each part of the device. Memory 27 includes a main storage device such as RAM (Random Access Memory) and an auxiliary storage device such as flash memory, and stores programs executed for blood pressure measurement processing, as well as data such as cuff pressure, pressure pulse wave, and blood pressure measurement results.

[0027] Display 25 is an example of a display device that displays various information such as blood pressure measurement results, and may be, for example, an LCD (Liquid Crystal Display). Operation switch 26 is an example of an input device for inputting various instructions related to the operation of the device, including the execution of blood pressure measurement. A touch panel display or the like may also be used as display 25 and operation switch 26. Power supply 24, which supplies power to each component of the device, such as the CPU, may receive power from an outlet via a wired connection, or may be a battery.

[0028] The oscillator circuit 21 outputs a signal having 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 pressure pump 13 based on a 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.

[0029] Fig. 2 is a functional block diagram showing functional modules included in the CPU 100 of the blood pressure measurement device 1. As shown in Fig. 2, the CPU 100 includes functional modules of a pressure detection unit 110, a pressure control unit 120, a first blood pressure calculation unit 130, a threshold value attainment determination unit 140, a second blood pressure calculation unit 150, and a stop cuff pressure determination unit 160.

[0030] The output signal of oscillator circuit 21 is input to pressure detection unit 110. Pressure detection unit 110 detects the oscillation frequency of the input signal and converts the detected oscillation frequency into a pressure value signal. Pressure detection unit 110 includes an HPF (High Pass Filter) unit 111 that applies HPF (High Pass Filter) processing to the pressure value signal to extract and output a pressure pulse wave signal, and an LPF (Low Pass Filter) unit 112 that applies LPF (Low Pass Filter) processing to the pressure value signal to extract and output a cuff pressure signal. The pressure pulse wave signal detected in time series by HPF unit 111 of pressure detection unit 110 and the cuff pressure signal indicating the cuff pressure detected in time series by LPF unit 112 are stored in a predetermined area of ​​memory 27 and transmitted to smartphone 50 via communication IF 28. Note that HPF unit 111 corresponds to a pulse wave information acquisition unit of the present invention.

[0031] 3 and 4 are graphs that schematically show the relationship between the cuff pressure detected by the pressure detection 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, as shown in Fig. 3, the minimum blood pressure (DIA, diastolic blood pressure, DBP) and the maximum blood pressure (SYS, systolic blood pressure, SBP) are calculated as the cuff pressure corresponding to a specific fluctuation pattern of the pressure pulse wave.

[0032] The pressure control unit 120 controls the operation of the pump drive circuit 22 and the valve drive circuit 23 to control the cuff pressure of the cuff 11 .

[0033] The first blood pressure calculation unit 130 receives the pressure pulse wave signal extracted by the HPF unit 111 of the pressure detection unit 110 and processes the received pressure pulse wave signal according to the oscillometric method to calculate the diastolic blood pressure and the systolic blood pressure. The oscillometric method is a well-known technique, so a detailed explanation will be omitted.

[0034] The threshold reach determination unit 140 determines whether the cuff pressure obtained from the LPF unit 112 of the pressure detection unit 110 has exceeded a threshold for switching the blood pressure measurement method from the method using the first blood pressure calculation unit 130 to the method using the second blood pressure calculation unit 150, which will be described later. The threshold can be set to a value at which the subject does not feel pain (discomfort) from the pressure, and can be set to, for example, 100 mmHg.

[0035] The second blood pressure calculation unit 150 calculates an estimated blood pressure value based on pressure pulse wave data acquired while the cuff pressure reaches a cuff pressure lower than the cuff pressure corresponding to the subject's systolic blood pressure, rather than calculating blood pressure using an oscillometric method. As shown in Figures 3 and 4, DIA can be detected before the envelope peak of the pressure pulse wave, i.e., at a cuff pressure lower than the cuff pressure corresponding to the envelope peak. Furthermore, the envelope peak is located before SYS, i.e., the cuff pressure corresponding to the envelope peak is lower than the cuff pressure corresponding to SYS. Taking these points into consideration, the cuff pressure at which the envelope peak occurs may be determined to be a cuff pressure lower than the cuff pressure corresponding to the subject's systolic blood pressure.

[0036] Stop cuff pressure determination unit 160 determines a cuff pressure (hereinafter referred to as inflation stop cuff pressure) for stopping inflation of cuff 11 as soon as possible after acquiring the pressure pulse wave data necessary for blood pressure calculation by second blood pressure calculation unit 150. If 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 of the envelope, as shown in FIG. 4, the inflation stop cuff pressure will be a cuff pressure that (slightly) exceeds the cuff pressure corresponding to the peak of the envelope. Note that the inflation stop cuff pressure may be determined, for example, by calculating DBP and using this as a reference. Specifically, the cuff pressure can be determined, for example, by the following method.

[0037] As indices obtained based on information on the pressure pulse wave, the indices RAV, WID, and DFN are known, as shown in the above-mentioned Patent Document 2. These are calculated for each beat of the pressure pulse wave. RAV, WID, and DFN are indices used to measure the area, width, and slope of the pulse wave per beat, respectively. Specifically, RAV is the pulse wave area per beat normalized by amplitude, and is expressed as (pulse wave area / pulse wave amplitude within one beat) x 100. WID is the waveform width, which is the time width from the maximum amplitude until it drops to the threshold, normalized by the pulse wave period, and is expressed as (waveform width / pulse wave period) x 100. DFN is the minimum value of the first derivative of the pressure pulse wave normalized by the pulse wave amplitude, and is expressed as (minimum value from 0 of the first derivative of the pulse wave / pulse wave amplitude of the first derivative of the pulse wave) x 100.

[0038] When the cuff pressure that becomes DBP is 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 the three indices RAV, WID, and DFN, but it may be expressed as any one or any two of the indices. The form of the function f is not particularly limited, but by calculating these indices for each beat of the pressure pulse wave acquired by the HPF unit 111, it is possible to determine whether the cuff pressure has reached DBP.

[0039] When the inflation stop cuff pressure is P1, the relationship between the cuff pressure value and DBP is expressed by a predetermined relational expression, such as P1 = g(Pd). Note that the form of function g is not particularly limited. If the pressure pulse wave data up to the peak of the envelope is used to estimate blood pressure by second blood pressure calculation unit 150, the inflation stop cuff pressure can be set to a cuff pressure slightly higher than the cuff pressure corresponding to the peak of the envelope.

[0040] (Blood pressure measurement process) Next, the flow of the blood pressure measurement process by the blood pressure measurement device in this embodiment will be described with reference to Fig. 5. Fig. 5 is a flowchart showing the flow of the blood pressure measurement process by the blood pressure measurement device 1 in this embodiment.

[0041] Before starting the processing described below, the subject wraps cuff 11 around the part to be measured (for example, the upper arm), performs predetermined settings using operation switch 26, and issues a command to start blood pressure measurement. In addition, it is assumed that blood pressure measurement device 1, which has received the command to start blood pressure measurement, has performed predetermined initialization, such as opening exhaust valve 14 and setting the cuff pressure to atmospheric pressure (initial pressure).

[0042] When blood pressure measurement is started in the blood pressure measurement device 1, the pressure control unit 120 starts inflation control to inflate the cuff 11 (S101). Furthermore, during the inflation control process, the HPF unit 111 of the pressure detection unit 110 acquires a pressure pulse wave (S102), and the LPF unit 112 acquires the cuff pressure. Next, the threshold reach determination unit 140 determines whether the acquired cuff pressure exceeds a threshold (e.g., 100 mmHg) (S103).

[0043] If it is determined in step S103 that the cuff pressure does not exceed the threshold, the first blood pressure calculation unit 130 executes a process of calculating the blood pressure value by the oscillometric method based on the pressure pulse wave acquired over time (S104). Then, the CPU 100 determines whether or not the calculation of the blood pressure value by the first blood pressure calculation unit 130 (i.e., by the oscillometric method) has been completed (S105). Here, if it is determined that the blood pressure calculation by the first blood pressure calculation unit 130 has been completed, the process proceeds to step S108. On the other hand, if it is determined in step S105 that the blood pressure calculation by the first blood pressure calculation unit 130 has not been completed, the process returns to step S102 and repeats the subsequent processes. Note that, hereinafter, the blood pressure value calculated by the first blood pressure calculation unit 130 is also referred to as the first calculated value. The first calculated value corresponds to the first blood pressure in the present invention.

[0044] On the other hand, if it is determined in step S103 that the cuff pressure exceeds the threshold, the stop cuff pressure determination unit 160 performs processing to determine the inflation stop cuff pressure (S106), and further, the LPF unit 11 It is determined whether the cuff pressure acquired from the CPU 2 has reached the inflation stop cuff pressure determined in step S106 (S107). The inflation stop cuff pressure is determined as described above.

[0045] If it is determined in step S107 that the cuff pressure has not yet reached the inflation stop cuff pressure, the process returns to step S102 and repeats the subsequent processes. On the other hand, if it is determined in step S107 that the cuff pressure has reached the inflation stop cuff pressure, the process proceeds to step S108.

[0046] In step S108, the pressure control unit 120 stops inflating the cuff 11 (S108). Subsequently, the CPU 100 executes a process of determining whether or not the calculation of the blood pressure value by the first blood pressure calculation unit 130 has been completed (S109). If it is determined that the calculation of the blood pressure value by the first blood pressure calculation unit 130 has been completed, 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 predetermined area of ​​the memory 27 of the blood pressure measurement device 1 (S112), and ends the series of blood pressure measurement processes.

[0047] On the other hand, if it is determined in step S109 that the calculation of the blood pressure value by the first blood pressure calculation unit 130 has not been completed, the second blood pressure calculation unit 150 executes a process of estimating the blood pressure value based on the pressure pulse wave data acquired before the inflation stop cuff pressure is reached (S110). The blood pressure value calculated by the second blood pressure calculation unit 150 is also referred to as the second calculated value hereinafter. The second calculated value corresponds to the second blood pressure according to the present invention. Then, 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 results including the blood pressure value in a predetermined area of ​​the memory 27 of the blood pressure measurement device 1 (S112), and ends the blood pressure measurement process.

[0048] With the blood pressure measurement device 1 described above, if blood pressure calculation using the oscillometric method is completed before the cuff pressure of the inflated cuff 11 exceeds a predetermined threshold, the blood pressure calculated using the highly accurate oscillometric method can be used as the measured value. On the other hand, if blood pressure measurement using the oscillometric method is not completed even after the cuff pressure exceeds the threshold, inflation of the cuff 11 is stopped before the cuff pressure reaches the cuff pressure corresponding to the systolic blood pressure, and blood pressure estimation is performed using pressure pulse wave data up to the inflation stop cuff pressure, thereby reducing the discomfort of the subject. In other words, the subject does not need to select in advance which method to use for blood pressure measurement. Simply starting blood pressure measurement reduces pain and discomfort caused by compression of the cuff 11, and blood pressure can be automatically calculated using a more accurate method.

[0049] <Example 2> Next, a second embodiment of the present invention will be described with reference to Figures 6 to 8. The hardware configuration of a blood pressure measurement device 2 according to this embodiment is similar to that of embodiment 1. Therefore, for components common to embodiment 1, such as the hardware configuration, the same reference numerals as in embodiment 1 will be used in the drawings, and a repeated description will be omitted.

[0050] 6, the blood pressure measurement device 2 according to the present embodiment differs from that according to the first embodiment 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 calculates the blood pressure of the subject using the blood pressure value calculated by the first blood pressure calculation unit 130 (first calculated value) and the blood pressure value calculated by the second blood pressure calculation unit 150 (second calculated value).

[0051] Specifically, when both the first estimated blood pressure and the second estimated blood pressure have been calculated, the third blood pressure calculation unit 170 calculates the average value of these values. More specifically, the third blood pressure calculation unit 170 calculates the average value after weighting the first calculated value and the second calculated value according to the blood pressure attribute of the subject (high blood pressure, low blood pressure, normal blood pressure). FIG. 7 shows the calculations performed by the third blood pressure calculation unit 170. 10 is a table illustrating an example of an average value to be calculated.

[0052] As shown in Fig. 7, for a subject with low blood pressure, the weight of the first calculated value is increased, and conversely, for a subject with high blood pressure, the weight of the second calculated value is increased, and an average value of both calculated values ​​is calculated. Note that the degree of weighting and the parameters that serve as the basis for weighting can be set appropriately and are not limited to the example shown in Fig. 7.

[0053] Depending on the attributes of the subject's blood pressure or the measurement environment, the second calculated value may be a more accurate measurement value than the first calculated value (particularly when a trained inference model is used as the second blood pressure calculation unit.) Therefore, if both values ​​can be calculated, the third blood pressure calculation unit 170 can average both values ​​using the method described above to prevent a less accurate value from being taken as the measurement value.

[0054] Next, the flow of the blood pressure measurement process in this embodiment will be described with reference to Fig. 8. Fig. 8 is a flowchart showing the flow of the blood pressure measurement process in this embodiment. In this embodiment, the overall flow of the blood pressure measurement process is generally similar to that in the first embodiment.

[0055] First, when blood pressure measurement is started in the blood pressure measurement device 2, the pressure control unit 120 starts inflation control to inflate the cuff 11 (S201). Furthermore, during the inflation control process, the HPF unit 111 of the pressure detection unit 110 acquires a pressure pulse wave (S202), and the LPF unit 112 acquires the cuff pressure. Next, the threshold reach determination unit 140 determines whether the acquired cuff pressure exceeds a threshold (e.g., 100 mmHg) (S203).

[0056] If it is determined in step S203 that the cuff pressure does not exceed the threshold, first blood pressure calculation unit 130 executes a process of calculating blood pressure values ​​by the oscillometric method based on the pressure pulse waves acquired over time (S204). Then, CPU 100A determines whether or not the calculation of blood pressure values ​​by first blood pressure calculation unit 130 (i.e., by the oscillometric method) has been completed (S205). Here, if it is determined that the blood pressure calculation by first blood pressure calculation unit 130 has not been completed, the process returns to step S202, and the subsequent processes are repeated.

[0057] On the other hand, if it is determined in step S205 that the blood pressure calculation by the first blood pressure calculation unit 130 has been completed, the process proceeds to step S206, unlike in Example 1. That is, in this example, even if the blood pressure calculation by the first blood pressure calculation unit 130 has been completed, this does not immediately cause cuff inflation to be stopped. However, once the blood pressure calculation by the first blood pressure calculation unit 130 has been completed, it is highly likely that almost all pressure pulse wave data forming the envelope, as shown in Figures 3 and 4, has been acquired, and the inflation stop cuff pressure will usually be reached without any delay.

[0058] If it is determined in step S203 that the cuff pressure exceeds the threshold value, the stop cuff pressure determination unit 160 performs a process to determine the inflation stop cuff pressure (S206), and further determines whether the cuff pressure obtained from the LPF unit 112 has reached the inflation stop cuff pressure determined in step S206 (S207).

[0059] If it is determined in step S207 that the cuff pressure has not yet reached the inflation stop cuff pressure, the process returns to step S202 and repeats the subsequent processes. On the other hand, if it is determined in step S207 that the cuff pressure has reached the inflation stop cuff pressure, the process proceeds to step S208.

[0060] In step S208, the inflation of the cuff 11 is stopped under the control of the pressure control unit 120 (S208). Subsequently, the second blood pressure calculation unit 150 executes a process of calculating (estimating) a blood pressure value based on the pressure pulse wave data acquired up until the inflation stop cuff pressure is reached (S209). When the calculation of the blood pressure value by the output unit 150 is completed, the CPU 100A determines whether or not both the first calculated value and the second calculated value have been calculated (S210).

[0061] If it is determined in step S210 that both the first and second calculated values ​​have been calculated (Yes in step S210), third blood pressure calculation unit 170 uses the first and second calculated values ​​to calculate an average value (S211). Note that, hereinafter, the value calculated by third blood pressure calculation unit 170 in step S211 is also referred to as the third calculated value. The third calculated value corresponds to the third blood pressure of the present invention. Details of the calculation process by third blood pressure calculation unit 170 are as described above.

[0062] When the third calculated value is calculated, the CPU 100A displays the third calculated value as a measurement value on the display 25 (S212), records the measurement results including the measurement value in a predetermined area of ​​the memory 27 of the blood pressure measurement device 2 (S213), and ends the series of blood pressure measurement processes.

[0063] On the other hand, if it is determined in step S210 that only the second calculated value has been calculated (No in step S210), and if it is determined that the calculation of the blood pressure value by the first blood pressure calculation unit 130 has not been completed, the CPU 100A displays the second calculated value as a measurement value on the display 25 (S212), records the measurement results including the measurement value in a predetermined area of ​​the memory 27 of the blood pressure measurement device 2 (S213), and ends the series of blood pressure measurement processes.

[0064] According to the blood pressure measurement device 2 of this embodiment, the first and second calculated values ​​are appropriately weighted and then averaged, thereby preventing a value with lower accuracy from being used as the measured value. In other words, the accuracy of the calculated blood pressure values ​​as a whole can be increased.

[0065] <Other> The above examples are merely illustrative of the present invention, and the present invention is not limited to the specific embodiments described above. Various modifications and combinations of the present invention are possible within the scope of the technical concept. For example, although the first blood pressure calculation unit 130 calculates blood pressure using the oscillometric method in each embodiment, it may also calculate blood pressure using other methods, such as the auscultation method or the volume compensation method.

[0066] The second blood pressure calculation unit 150 may also be configured to estimate the blood pressure of the subject based on the pulse wave information acquired before the inflation stop cuff pressure is reached, and may be configured as an inference model that has been trained by machine learning, for example.

[0067] Furthermore, although the inflation stop cuff pressure is determined based on the peak of the envelope in each of the above examples, it is not limited to this. It may be any cuff pressure at any point up to the cuff pressure corresponding to the subject's systolic blood pressure, and the inflation stop cuff pressure may be determined based on a landmark such as the characteristic of the envelope slope (a point where the upward or downward slope becomes steep, or a point where the slope stabilizes). [Explanation of symbols]

[0068] 1, 2... Blood pressure measuring device 11. Cuff 15. Air tube 100, 100A···CPU 110 Pressure detection unit 120 Pressure control section 130 First blood pressure calculation unit 140 Threshold reaching determination unit 150 Second blood pressure calculation unit 160...Stop cuff pressure determination section 170 Third blood pressure calculation unit

Claims

1. a cuff that is wrapped around the part to be measured; 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 acquiring unit that acquires pulse wave information of the subject from the cuff pressure; a first blood pressure calculation unit that calculates a first blood pressure of the subject based on the pulse wave information; a second blood pressure calculation unit that calculates a second blood pressure of the subject based on the pulse wave information acquired before the cuff pressure reaches an inflation stop cuff pressure; a stop cuff pressure determination unit that determines the value of the inflation stop cuff pressure based on characteristics of the pulse wave information acquired at the cuff pressure lower than the inflation stop cuff pressure; a threshold reaching determination unit that determines whether the cuff pressure has reached a predetermined determination threshold related to the termination of first blood pressure calculation, When the cuff pressure reaches a predetermined determination threshold, the first blood pressure calculation unit stops calculating the first blood pressure. Blood pressure measuring device.

2. a display unit that displays the first blood pressure as a measured blood pressure value when calculation of the first blood pressure is completed. The blood pressure measuring device according to claim 1 .

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

4. a third blood pressure calculation unit that calculates a third blood pressure of the subject using the first blood pressure and the second blood pressure; a display unit that displays the third blood pressure as a measured blood pressure value, the pressure control unit continues to inflate the cuff until the cuff pressure reaches the inflation stop cuff pressure even after the calculation of the first blood pressure is completed. The blood pressure measuring device according to claim 1 .

5. the third blood pressure calculation unit calculates the third blood pressure after weighting the first blood pressure and the second blood pressure according to a predetermined parameter. The blood pressure measuring device according to claim 4.

6. In the blood pressure measuring device, detecting a cuff pressure in a cuff wrapped around the measurement target part; Increasing the cuff pressure; acquiring pulse wave information of the subject from the cuff pressure; executing a process of calculating a first blood pressure of the subject based on the pulse wave information; executing a process of calculating a second blood pressure of the subject based on the pulse wave information acquired before the cuff pressure reaches an inflation stop cuff pressure; determining a value of the inflation stop cuff pressure based on characteristics of the pulse wave information acquired at a cuff pressure lower than the inflation stop cuff pressure; determining whether the cuff pressure has reached a predetermined determination threshold for stopping calculation of the first blood pressure; and stopping the calculation of the first blood pressure when the cuff pressure reaches a predetermined determination threshold. How to measure blood pressure.

7. When the calculation of the first blood pressure is completed, displaying the first blood pressure as a measured blood pressure value. The blood pressure measurement method according to claim 6.

8. and if the calculation of the first blood pressure is stopped, displaying the second blood pressure as a measured blood pressure value. The blood pressure measurement method according to claim 6.

9. calculating a third blood pressure of the subject using the first blood pressure and the second blood pressure; and displaying the third blood pressure as a measured blood pressure value. In the step of increasing the cuff pressure, the cuff is increased until the cuff pressure reaches the inflation stop cuff pressure even after the calculation of the first blood pressure has been completed. The blood pressure measurement method according to claim 6.

10. In the step of calculating the third blood pressure, the first blood pressure and the second blood pressure are weighted according to a predetermined parameter, and then the third blood pressure is calculated. The blood pressure measurement method according to claim 9.

11. A program for causing a blood pressure measurement device to execute each step of the blood pressure measurement method according to any one of claims 6 to 10.

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