Electronic blood pressure monitor

Abstract

Electronic blood pressure monitor (1), which comprises: a cuff (20) which can be worn at a measuring location; a pressure adjustment unit (51, 52) which adjusts the pressure within the cuff (20) by increasing or decreasing pressure; a pressure detection unit including a plurality of pressure sensors (321, 322) and configured to detect the cuff pressure within the cuff (20) based on the pressure information output from the plurality of pressure sensors; a blood pressure calculation unit (112) which calculates a blood pressure based on the change in cuff pressure, which is detected by the pressure detecting unit at a time of blood pressure measurement; a maintenance unit (111) which maintains the cuff pressure at a predetermined pressure at the time of blood pressure measurement; and an abnormality detection unit (113) which, in a state in which the maintenance unit maintains the cuff pressure at a predetermined pressure, detects whether an abnormality has occurred in at least one of the plurality of pressure sensors (321, 322), based on the pressure information output by the plurality of pressure sensors (321, 322).

Description

Technical area

[0001] The present invention relates to an electronic blood pressure monitor and, more particularly, to an electronic blood pressure monitor which improves the reliability of blood pressure measurements. Background of the state of the art

[0002] Blood pressure is an index for analyzing cardiovascular diseases. Conducting cardiovascular disease risk assessment based on blood pressure is effective in preventing cardiovascular-related conditions such as stroke, heart failure, and myocardial infarction. Specifically, early morning high blood pressure, in which blood pressure rises early in the morning, is related to heart disease, stroke, and the like. Among the symptoms of early morning high blood pressure, the symptom called "morning surge," in which blood pressure rises rapidly within one to one and a half hours after waking up, has been found to have a causal relationship with stroke. Therefore, understanding the relationship between time (lifestyle) and changes in blood pressure is useful for risk analysis of cardiovascular conditions.It is therefore necessary to measure blood pressure continuously over a long period of time.

[0003] Recent studies have also found that home blood pressure measurements are more effective for the prevention, diagnosis, and treatment of cardiovascular disease-related conditions than blood pressure measurements taken in a clinic or during a medical checkup (casual blood pressure). Accordingly, home blood pressure monitors have become widespread, and home blood pressure measurements have begun to be used for diagnosis.

[0004] In order to improve the measurement accuracy of blood pressure monitors, an invention is disclosed in Patent Literature 1 (JP H07 - 51 233 A) in which the processing for correcting the error in a measured value, which depends on the characteristics of the blood pressure sensor for blood pressure measurement, is performed in the production stage of the electronic blood pressure monitor. Citation listPatent literature

[0005] Patent literature 1: JP H07 - 51 233 A

[0006] EP 0 342 249 A1 describes a monitoring device for the automatic, non-invasive measurement of a patient's blood pressure. The monitoring device comprises a means for automatically inflating and deflating a cuff to be applied to a patient's extremity. A processor device receives signals from pressure sensors and accesses stored calibration values ​​to compare them with the signals.

[0007] JP H05 - 23 310 A describes a device that can test the pressure difference between a pressure cuff and a reference device. By closing valves, a pressure pump builds up pressure in the pressure cuff and a bag of the reference device, and the pressure in the pressure cuff and bag is then measured with a pressure sensor.

[0008] WO 2009 093 515 A1 describes a precision confirmation device in which the connection of a connector plug to the port of a hemadynamometer connects an air system to the measurement air system of a main body and connects a CPU to the CPU of the hemadynamometer via a communication line. During operation, the CPU receives pressure values ​​from the hemadynamometer and the precision confirmation device to subsequently determine the measurement accuracy of the hemadynamometer. Summary of the inventionTechnical problem

[0009] According to Patent Literature 1 (JP H07-51233A), the correction of the pressure sensor is performed based on differences in the characteristics of the electronic sphygmomanometers during the production stage of the electronic sphygmomanometer. This type of electronic sphygmomanometer is a home-use sphygmomanometer. Unlike a sphygmomanometer used in a medical environment such as a hospital, a home-use sphygmomanometer is generally not periodically corrected after purchase, except for specific situations such as malfunction. Therefore, even if the pressure sensor output, which is of utmost importance for blood pressure measurement, falls below the specified tolerance limit, there is no way to know that this has occurred, and therefore it is unclear whether the blood pressure readings are accurate.Also, even if there is a large difference between a blood pressure reading and the normal blood pressure reading or the occasional blood pressure reading, it is not clear whether the current blood pressure values ​​are different, or the blood pressure values ​​are different due to a fault in the blood pressure sensor of the blood pressure monitor, so this causes concern to the user.

[0010] Also, some blood pressure monitors for medical facilities include two pressure sensors, and the pressure is monitored based on the output signals of the two pressure sensors. However, the functions of these two pressure sensors are used for different purposes in such blood pressure monitors. Here, the blood pressure is calculated using the cuff pressure information obtained by a first of the pressure sensors, and abnormality detection is performed based on the output signal of the second pressure sensor. Specifically, an abnormality is detected when the pressure value detected by the second pressure sensor greatly exceeds, for example, 300 mmHg. In this case, safety is ensured by stopping or stopping a valve that releases the pump.Accordingly, the second pressure sensor is used for a safety measurement, which is specified in the medical standard IEC 60601-2-30, and does not guarantee the precision of the first pressure sensor, which is used for blood pressure measurement.

[0011] In view of the above, it is an object of the present invention to provide an electronic blood pressure monitor which improves the reliability of blood pressure readings in blood pressure measurement using many pressure sensors. Solution to the problem

[0012] An electronic blood pressure monitor according to one aspect of the present invention includes: a cuff worn at a measurement site; a pressure adjustment unit that adjusts the pressure inside the cuff by increasing or decreasing pressure; a pressure detection unit that includes a plurality of pressure sensors and is for detecting the cuff pressure inside the cuff based on the pressure information output from the plurality of pressure sensors; a blood pressure calculation unit that calculates a blood pressure based on the change in the cuff pressure detected by the pressure detection unit at a time of blood pressure measurement; a maintenance unit that maintains the cuff pressure at a predetermined pressure at the time of blood pressure measurement.and an abnormality detection unit that, in a state where the maintenance unit maintains the cuff pressure at the predetermined pressure, detects whether an abnormality has occurred in at least one of the plurality of pressure sensors based on the pressure information output from the plurality of pressure sensors;

[0013] It is preferable that the blood pressure measurement includes a pressure build-up process in which the cuff is pressurized by the pressure setting unit after the blood pressure measurement is started, a pressure reduction process which depressurizes the cuff, and a transition period from after the pressure build-up process is finished until the pressure reduction process is started, and the maintaining unit maintains the pressure applied in the cuff at the predetermined pressure in at least one of the pressure build-up process, the pressure reduction process, and the transition period.

[0014] It is preferable that the predetermined pressure indicates the cuff pressure at the time when the pressure build-up process is completed.

[0015] It is preferable that the abnormality detection unit includes a stabilization detection unit that detects whether the cuff pressure is maintained at the predetermined pressure based on the pressure information output from the plurality of pressure sensors, and in a case where the stabilization detection unit has detected that the cuff pressure is maintained at the predetermined pressure, the abnormality detection unit detects whether an abnormality has occurred in at least one of the plurality of pressure sensors based on the pressure information output from the plurality of pressure sensors.

[0016] It is preferable that the stabilization detecting unit detects, with respect to the pressure information outputted in time series from one of the plurality of pressure sensors, a difference in the pressure information at a plurality of time points, and detects whether the cuff pressure is maintained at the predetermined pressure based on the detected difference.

[0017] It is preferable that the stabilization detecting unit detects representative pressure information based on the pressure information output by one of the pressure sensors at the plurality of times, and, based on the representative pressure information, extracts the pressure information for detecting the difference from the pressure information at the plurality of times output by at least one of the plurality of pressure sensors.

[0018] It is preferable that, based on the pressure information at a plurality of time points output by the plurality of pressure sensors in time series, the stabilization detecting unit detects a difference in the pressure information at each of the time points, and detects whether the cuff pressure is maintained at the predetermined pressure based on a difference between the detected differences.

[0019] It is preferable that the stabilization detecting unit detects representative pressure information based on the pressure information output by the plurality of pressure sensors at the plurality of time points, and, based on the representative pressure information, extracts the pressure information for detecting the difference from the pressure information at the plurality of time points output by the plurality of pressure sensors.

[0020] It is preferable that the blood pressure measurement is stopped in a case where the abnormality detecting unit has detected the occurrence of an abnormality of at least one of the plurality of pressure sensors.

[0021] It is preferable that the electronic blood pressure monitor further includes a storage unit, wherein each time the abnormality detection unit detects whether an abnormality has occurred in at least one of the plurality of pressure sensors, the storage unit stores a result of the detection, and when the blood pressure measurement is to be started, in a case where a determination has been made that the result of the detection read out from the storage unit indicates that an abnormality has occurred, the blood pressure measurement is stopped, and the result of the detection read out is outputted.

[0022] It is preferable that the electronic blood pressure monitor outputs a detection result performed by the abnormality detection unit.

[0023] It is preferable that, in a case where the abnormality detecting unit has detected that an abnormality has occurred in at least one of the plurality of pressure sensors, the blood pressure measurement is terminated, and thereafter, a result of the detection performed by the abnormality detecting unit is outputted.

[0024] It is preferable that the electronic blood pressure monitor further includes a data storage unit that stores blood pressure data indicative of the blood pressure calculated by the blood pressure calculation unit and a detection result performed by the abnormality detection unit together with the blood pressure data, wherein, within the blood pressure data in the storage unit, the blood pressure data corresponding to a detection result indicating the occurrence of an abnormality is excluded from the blood pressure data used for calculating statistics.

[0025] It is preferable that in a case where the stabilization detection unit has not detected that the cuff pressure is maintained at the predetermined pressure, an alarm of this fact is given.

[0026] It is preferable that in a case where the stabilization detecting unit has not detected that the cuff pressure is maintained at the predetermined pressure, the pressure adjusting unit builds up the cuff in pressure, and thereafter the stabilization detecting unit again detects whether the cuff pressure is maintained at the predetermined pressure. Advantageous effects of the invention

[0027] According to the present invention, in the blood pressure measurement process performed based on cuff pressures detected using multiple pressure sensors, abnormality detection is performed with respect to at least one of the pressure sensors based on pressure information detected while the cuff pressures were maintained at a predetermined pressure. This allows accurate abnormality detection to be performed. Short description of the drawings Fig. 1 is an external view of an electronic blood pressure monitor according to an embodiment. Fig. 2 is a diagram of a hardware configuration of the electronic blood pressure monitor according to the embodiment. Fig. 3 is a diagram of a functional configuration of the electronic blood pressure monitor according to the embodiment. Fig. 4 is a diagram illustrating blood pressure calculation according to the embodiment. Fig. 5 is a graph showing the timing of pressure sensor abnormality detection during blood pressure measurement according to the embodiment. Fig. 6 is a diagram for illustrating a stable period of a cuff pressure signal according to the embodiment. Fig. 7A to 7C are diagrams for illustrating a comparison of a reference value and an example of the change in the differences between the output signals of the pressure sensors according to the embodiment. Fig. 8A and Fig. 8B are diagrams for illustrating a comparison of the difference value and another example of the change in the differences between the output signals of the pressure sensors according to the embodiment. Fig. 9 is a flowchart of processing for performing sensor abnormality detection at the end of a pressure build-up process in blood pressure measurement according to the embodiment. Fig. 10 is a flowchart of processing for performing pressure sensor abnormality detection in the case of calculating a blood pressure in the pressurization process according to the embodiment. Fig. 11 is a flowchart of another processing for performing pressure sensor abnormality detection in the case of calculating a blood pressure in the pressurization process according to the embodiment. Fig. 12 is a flowchart of processing for performing pressure sensor abnormality detection in the case of calculating a blood pressure in a degradation process according to the embodiment. Fig. 13 is a flowchart of another processing for performing pressure sensor abnormality detection in the case of calculating a blood pressure in the pressure reduction process according to the embodiment. Fig. 14 is a flowchart of processing for performing pressure sensor abnormality detection after the pressure build-up process or the reconstruction in the pressure reduction process according to the embodiment. Fig. 15 is a flowchart of the processing for retrying pressure sensor abnormality detection in the pressure reduction process according to the embodiment. Fig. 16 is a diagram for illustrating an example of a display according to the embodiment. Fig. Figure 17 is an external view of a wrist-mounted electronic blood pressure monitor. Description of the embodiments

[0028] The following is a detailed description of an embodiment of the present invention with reference to the drawings. Note that like reference numerals denote similar or corresponding parts throughout the drawings, and redundant descriptions will be omitted.

[0029] The present embodiment describes an electronic blood pressure monitor that includes multiple pressure sensors and performs oscillometric blood pressure calculation using the upper arm as the measurement site. Note that the method used for blood pressure calculation is not limited to the oscillometric method.

[0030] Fig. Fig. 1 is an external view of an electronic blood pressure monitor 1 according to this embodiment of the present invention, and Fig. 2 shows the hardware configuration of the electronic blood pressure monitor. As shown in Fig. 1 and Fig. As shown in Figure 2, the electronic blood pressure monitor 1 includes a main unit 10 and a cuff 20 that can be wrapped around the upper arm of a subject. The cuff 20 includes an air bladder 21. On the surface of the main unit 10 are a display unit 40 configured with a liquid crystal display or the like, and an operation unit 41 composed of multiple switches for receiving instructions from a user (the subject).

[0031] In addition to the display unit 40 and the operation unit 41 described above, the main unit 10 includes a CPU (central processing unit) 100 for performing central control of various units and performing various types of arithmetic processing, a processing memory 42 for storing data and programs for causing the CPU 100 to perform predetermined operations, a data storage device 43 for storing measured blood pressure data and the like, a power supply 44 for supplying power to the various units in the main unit 10, and a timer 45 for measuring the current time and outputting time data to the CPU 100.

[0032] The operation unit 41 has a power supply switch (“PWR”) 41A for receiving the input of an instruction to turn the power supply on or off, a measurement switch (“MSR”) 41B for receiving the input of a measurement start instruction, a stop switch (“STP”) 41C for receiving a measurement stop instruction, a memory switch (“MEM”) 41D for receiving the input of an instruction to cause information such as the blood pressure data stored in the memory 43 to be read out from the memory 43 and displayed on the display unit 40, and a timer setting switch (“SET TMR”) 41E which is operated to set the timer 45.

[0033] The main unit 10 also has a cuff pressure adjustment mechanism which includes a pump 51 and an outlet valve (hereinafter simply referred to as “valve”) 52.

[0034] An air system is made up of the pump 51, the valve 52, and first and second pressure sensors 321 and 322 for detecting the pressure (cuff pressure) in the air bladder 21, and the air system is connected to the air bladder 21 enclosed in the cuff 20 via an air tube 31.

[0035] In addition to the air system and the cuff pressure adjustment mechanism described above, the main unit 10 further includes first and second oscillation circuits 331 and 332. The cuff pressure adjustment mechanism includes a pump drive circuit 53 and a valve drive circuit 54 in addition to the pump 51 and the valve 52.

[0036] The pump 51 operates to increase the cuff pressure. When the pump 51 operates, air is supplied to the air bladder 21. By opening or closing the valve 52, air is released from the air bladder 21 or air is trapped inside the air bladder 21. The pump drive circuit 53 controls the pump 51 based on a control signal transmitted from the CPU 100. The valve drive circuit 54 controls the valve 52 based on a control signal transmitted from the CPU 100. Accordingly, the pump 51 is controlled based on a control signal so as to be driven or stopped by the pump drive circuit 53, and the valve 52 is controlled based on a control signal so as to be opened or closed by the valve drive circuit 54.

[0037] The first and second pressure sensors 321 and 322 are capacitive pressure sensors in which the capacitance value changes according to the cuff pressure being detected. The first and second valve driving circuits 331 and 332 are connected to the corresponding pressure sensors, respectively, and oscillate based on the capacitance values ​​of the corresponding pressure sensors. Accordingly, the first and second valve driving circuits 331 and 332 each output a signal to the CPU 100 having a frequency corresponding to the capacitance value of the corresponding pressure sensor (hereinafter, referred to as a "frequency signal"). The CPU 100 performs pressure detection by converting the frequency signals input from the first valve driving circuit 331 and the second valve driving circuit 332 into a pressure.Here, it is assumed that the CPU 100 alternately inputs the frequency signals from the first valve driving circuit 331 and the second valve driving circuit 332 at staggered timings.

[0038] Fig. 3 shows the functional configuration of the electronic blood pressure monitor 1. As in Fig. 3, the CPU 100 includes a pressure setting unit 111, a blood pressure calculation unit 112, a sensor abnormality detection unit 113, a recording unit 114, and a display processing unit 115.

[0039] The pressure adjustment unit 111 controls the pump 51 and the valve 52 via the pump driver circuit 53 and the valve driver circuit 54 to cause air to flow into the air bladder 21 or to flow out of the air bladder 21 via the air tube 31. In this way, the pressure adjustment unit 111 adjusts the cuff pressure. It is assumed that some or all of the functions of these units are realized by the CPU 11, which reads corresponding programs and data from the memory 42 and executes the instructions described herein.

[0040] The blood pressure calculation unit detects pulse wave amplitude information based on a frequency signal input from the first valve drive circuit 331 or the second valve drive circuit 332 (the frequency signal indicative of a pressure information signal), calculates a systolic blood pressure SYS corresponding to the maximum blood pressure and a diastolic blood pressure DIA corresponding to the minimum blood pressure based on the detected pulse wave amplitude information according to the oscillometric method, and also calculates a number of pulse beats per predetermined time based on the detected pulse wave amplitude information.Specifically, in the process in which the pressure adjustment unit 111 gradually increases (or decreases) the cuff pressure to a predetermined value, the blood pressure calculation unit 112 detects the pulse wave amplitude information based on the cuff pressure input from the first valve drive circuit 331 or the second valve drive circuit 332, and calculates the systolic blood pressure and the diastolic blood pressure of the subject based on the detected pulse wave amplitude information. A conventionally known method can be applied to the blood pressure calculation and the pulse calculation, which is performed by the blood pressure calculation unit 112 according to the oscillometric method.

[0041] The sensor abnormality detection unit 113 receives input of frequency signals output from the first oscillation circuit 331 and the second oscillation circuit 332 and performs abnormality detection with respect to the first pressure sensor 321 and the second pressure sensor 322 by analyzing the input signals.

[0042] The sensor abnormality detection unit 113 has a pressure build-up detection unit 1131 for performing abnormality detection in the cuff pressure pressurization process, a pressure reduction detection unit 1132 for performing abnormality detection in the cuff pressure pressurization process, a pressure build-up end detection unit 1133 for performing abnormality detection when the pressure build-up process ends, a stabilization detection unit 1134 for detecting the fact that the cuff pressure detected in the abnormality detection has stabilized, a re-pressurization request unit 1135.the re-pressurization unit 1136 for requesting the re-pressurization in the case where the cuff pressure has not stabilized, a re-detecting unit 1136 for re-performing the abnormality detection in the case where the cuff pressure has not stabilized, and an abnormality detecting unit 1137 for performing the pressure sensor abnormality detection based on a result of comparing the cuff pressures with a reference value.

[0043] The recording unit 114 has the functions of reading data from the memory 43 and writing the data into the memory 43. Specifically, the recording unit 114 receives an input of output data from the blood pressure calculation unit 112 and stores the input data (blood pressure measurement data) in a predetermined storage area of ​​the memory 43. The recording unit 114 also receives an input of output data from the sensor abnormality detection unit 113 and stores the input data (pressure sensor abnormality detection result) in a predetermined storage area of ​​the memory 43. Also, based on an operation performed on the memory switch 41D of the operation unit 41, the recording unit reads measurement data from a predetermined storage area of ​​the memory 43 and outputs the read data to the display processing unit 115.

[0044] The display processing unit 115 receives an input of data, converts the input data into a displayable format, and displays the data on the display unit 40.

[0045] Note that regarding the peripheral circuits of the CPU 100 Fig. 3 shows only parts that perform a direct exchange with the CPU 100.

[0046] Next, a description of the operations of the various units with reference to Fig. 4 to 18. The flow charts of the Fig. 9 to 15 are stored in advance as programs in the memory 42, and the processing of the various units is realized by the CPU 100, which reads the programs from the memory 42 and executes the read programs. (Blood pressure calculation procedure)

[0047] The following describes the concept of an oscillometric blood pressure calculation method according to the present embodiment. In (A) of the Fig. 4 shows the decrease of cuff pressures along a time axis, which is measured by the timer 45. In (B) the Fig. 4 shows an envelope 600 of a pulse wave amplitude along the same time axis, corresponding to the previously mentioned pulse wave amplitude information. The envelope 600 of the pulse wave amplitude is detected by a pulse wave amplitude signal superimposed on a signal (cuff pressure) from a pressure sensor, which is extracted in time series.

[0048] As in (A) and (B) of the Fig. As shown in Figure 4, upon detecting a maximum amplitude value MAX in the pulse wave amplitude envelope 600, the blood pressure calculation unit 112 calculates two threshold values ​​TH_DBP and TH_SBP by multiplying this maximum value by predetermined constants (e.g., 0.7 and 0.5). The cuff pressure at the intersection point between the threshold value TH_DBP and the envelope 600 on the low-pressure side of a cuff pressure MAP (average blood pressure) at time T0 at which the maximum value MAX was detected is then calculated as the diastolic blood pressure DIA. Likewise, the cuff pressure at the intersection point between the threshold value TH_SBP and the envelope 600 on the high-cuff pressure side of the cuff pressure MAP is then calculated as the systolic blood pressure SYS.

[0049] Although the blood pressure calculation in the pressure reduction process has been described above, it is possible to detect the pulse wave amplitude envelope 600 and calculate the systolic blood pressure SYS and the diastolic blood pressure DIA, and a similar procedure is also applied in the pressure build-up process. (Sensor abnormality determination method)

[0050] To improve the reliability of blood pressure measurement values, the sensor abnormality detection unit 113 performs abnormality detection in the following manner in the blood pressure measurement process. Specifically, the frequency signals input from the first and second oscillation circuits 331 and 332 are converted into cuff pressures a and b, respectively, and the cuff pressure a and cuff pressure b obtained by conversion are compared with a reference value β (e.g., 5 mmHg) described later. Based on the comparison result, a determination is made that an abnormality has occurred in one of the pressure sensors in the case where the difference between the cuff pressure a and the cuff pressure b exceeds the reference value β.

[0051] Also, in the case where three or more pressure sensors are used, the difference between the maximum value and the minimum value among the three or more cuff pressures obtained by conversion in a similar manner is calculated, and a determination is made that an abnormality has occurred in any one of the pressure sensors in the case where the calculated difference exceeds the reference value β.

[0052] In the case where the sensor abnormality detection unit 113 has determined that an abnormality has occurred in one of the pressure sensors, the blood pressure calculation unit 112 does not use the calculated blood pressure measurement data in the display or recording (i.e., disregards the calculated blood pressure measurement data) based on the determination result, thus enabling the reliability of the blood pressure measurement values ​​to be improved. Also, instead of disregarding the blood pressure measurement data, a configuration is possible in which the display unit 40 displays the blood pressure measurement data together with the information (a message) indicating that an abnormality has occurred in a pressure sensor (see Fig. 16, which will be described later). Also possible is a configuration in which such blood pressure measurement data is stored in the memory 43, together with an identifier indicating that an abnormality has occurred in a pressure sensor.

[0053] In the case where the blood pressure measurement data in the memory 43 is used to calculate statistics for determining whether the blood pressure of the measured person belongs to the category of hypertension, for example, a configuration is possible in which the blood pressure measurement data belonging to the aforementioned identifier within the blood pressure measurement data stored in the memory 43 is excluded from the data specifically taken for use in calculating the statistics.

[0054] Also, each time the sensor abnormality detection unit 113 performs the detection operation, the data 431 indicating the detection result (abnormality / normal) is stored in a predetermined area of ​​the memory 43 by overwriting. Then, a configuration is possible in which the CPU 100 reads the data 431 from the memory 43 when the start of blood pressure measurement is instructed by the switch 41B being operated, the blood pressure measurement is stopped and the readout data 431 is displayed on the display unit 40 when it is determined that the readout data 431 indicates an abnormality, and the pressure buildup for blood pressure measurement is started when it is determined that the readout data does not indicate an abnormality (ie, indicates normal operation). (Time sequence of pressure sensor abnormality detection)

[0055] An advantage of the present embodiment is that, since the step in which the sensor abnormality detection unit 113 performs the pressure sensor abnormality detection in the blood pressure measurement process, there is no need to provide a separate abnormality detection step.

[0056] Fig. Figure 5 schematically shows the change in cuff pressure Pc with time during blood pressure measurement. In blood pressure measurement, after the cuff is wrapped around the measurement site, pressure buildup is started in response to an operation performed on the measurement switch 41B. Once pressure buildup is started, the cuff pressure Pc gradually rises, and pressure buildup is continued until the cuff pressure Pc reaches a final pressure buildup pressure PE. This is referred to as the pressure buildup process.

[0057] After the pressure build-up end point PE is reached, the deflation process begins. Specifically, a transition to the depressurization process occurs by opening valve 52, allowing the air within cuff 20 to gradually escape. The diastolic blood pressure DIA and the systolic blood pressure SYS are also detected (calculated) during the depressurization process.

[0058] In the present embodiment, pressure sensor abnormality detection is performed in both the pressure build-up process and the pressure reduction process. Specifically, pressure sensor abnormality detection is performed when a cuff pressure Pc is lower than the diastolic blood pressure DIA that was detected (see pressures P1 and P4 in Fig. 5), and if a cuff pressure Pc which is higher than the systolic blood pressure SYS and lower than the pressure build-up end pressure PE has been detected (see pressures P2 and P3 in Fig. 5). Furthermore, pressure sensor abnormality detection is performed in the period from the end of the pressure build-up process to the start of the pressure reduction process. In the present invention, pressure sensor abnormality detection is assumed to be performed at least at any one or more of these times and periods.

[0059] Here it is assumed that the pressure build-up end pressure PE is a value which is 40 mmHg higher than the systolic blood pressure SYS, the pressure P3 is a value which is 20 mmHg lower than the pressure build-up end pressure PE and the pressure P4 is a value which is 20 mmHg lower than the diastolic blood pressure DIA. (Detection of stabilization of cuff pressure Pc)

[0060] In the present invention, when pressure sensor abnormality detection is to be performed, the cuff pressure is controlled to be constant, and abnormality detection is performed when the stabilization detection unit 1134 has detected that the cuff pressure is constant. This allows the accuracy of abnormality detection to be maintained.

[0061] The following describes the processing in which the stabilization detecting unit 1134 detects that the cuff pressure is constant, taking the example of the period from the end of the pressure build-up process to the start of the transition to the pressure reduction process (hereinafter, this period is referred to as the “transition period”), with reference to the Fig. 5 to 7C.

[0062] The stabilization detection unit 1134 detects the transition period based on an output signal from the pressure adjustment unit 111. Specifically, the stabilization detection unit 1134 detects the period from the time when the pressure adjustment unit 111 stops the pump 51 (i.e., ends the pressure build-up process) by outputting a stop signal to the pump drive circuit 53 to the time when the pressure adjustment unit 111 thereafter opens the closed valve 52 (i.e., starts the transition to the pressure reduction process) by outputting a signal to the valve drive circuit 54. In the transition period, the pump 51 is stopped and the valve 52 is fully closed, and therefore the cuff pressure is constant.

[0063] In the transition period, at a predetermined interval based on the time data from the timer 45 (at alternately different times PP1, PP2 and PP3 in Fig. 6), the stabilization detection unit 1134 calculates the cuff pressure detected by the first pressure sensor 321 based on an input signal from the first valve drive circuit 331 and subsequently calculates the cuff pressure detected by the second pressure sensor 322 based on an input signal from the second valve drive circuit 332. The difference between the detected cuff pressures of the first and second pressure sensors is then detected for each time lapse. The difference between the differences detected at the respective time lapses is then compared with a threshold value α (see Fig. 7A and Fig. 7B) read from the memory 43. The threshold value α is an allowable range value for allowing or prohibiting the operation of the pressure sensor abnormality detection, that is, the threshold value α indicates whether the cuff pressure is stable. Accordingly, as a result of the comparison, in the case where it is determined that the difference between the differences detected at the respective timings does not exceed the allowable range indicated by the threshold value α (see Fig. 7B), it is detected that the cuff pressure is constant during the transition period. If the cuff pressure is detected to be constant, the pressure sensor abnormality detection processing is started.

[0064] On the other hand, in the case where the cuff pressure fluctuates, due for example to a body movement of the person being measured in the transition period (area indicated by a broken line Fig. 7C, the difference between the differences exceeds the permissible range, which is indicated by the threshold value α) see Fig. 7A, it is detected that the cuff pressure is not stable and the pressure sensor abnormality detection processing is not started.

[0065] Note that even in the case where it has been detected that the cuff pressure is not stable, it is possible for the stabilized detecting unit 1134 to perform the cuff pressure stabilization detection again.

[0066] The above-described detection of cuff pressure stabilization by the stabilization detection unit 1134 is carried out by performing the same procedure at each of the pressures P1, P2, P3 and P4 in Fig. 5 is used.

[0067] Although cuff pressure stabilization detection is performed using the cuff pressures of both the first pressure sensor 321 and the second pressure sensor 322 in the above description, a configuration is possible in which stabilization detection is performed using the cuff pressures detected by any one of the pressure sensors. Specifically, a configuration is possible in which the cuff pressure of one of the pressure sensors is detected at each of the times PP1, PP2, and PP3, and it is detected that the cuff pressure is stable in the case where the difference between the cuff pressures detected at the respective times does not exceed a predetermined value.

[0068] The following describes the processing that can be performed to improve the precision in the stabilization detection described above, with reference to Fig. 8A and Fig. 8B.

[0069] As in Fig. 8B, even in the transition period, in the case where the amplitude fluctuation (see the part indicated by a broken line in Fig. 8B) resulting from a large disturbance (body movement or pulse wave) is superimposed on the cuff pressure signal, there is a large amount of fluctuation in the values ​​of the cuff pressures detected by the first pressure sensor 321 and the second pressure sensor 322. In view of this, the stabilization detection unit 1134 calculates an average value as a representative value for all the cuff pressures input from the first and second pressure sensors 321 and 322 in time series. The values ​​of each of the cuff pressures detected by the first pressure sensor 321 and the second pressure sensor 322 are then compared with a threshold value γ indicating a predetermined range including the average value. Whether the cuff pressures fall within the threshold value γ is detected based on the comparison results.As a result of the detection, all cuff pressure values ​​determined to fall outside the threshold γ are separated from the cuff pressure values ​​determined in . Fig. 8A, which are related to stabilization detection. Accordingly, extremely high and low cuff pressures are excluded from the reference values ​​to be used in stabilization detection. Accordingly, the cuff pressures related to stabilization detection, that is, cuff pressures to be used to detect the differences, can be selectively extracted based on the representative value from the cuff pressure values ​​output by the first pressure sensor 321 and the second pressure sensor 322 at multiple time points. This consequently allows for improving the precision in stabilization detection.

[0070] Although an average value is detected as the representative value in the above description, a median value may be used.

[0071] Although the representative value is detected using the cuff pressures of both the first sensor 321 and the second pressure sensor 322 in the above description, a configuration is possible in which the representative value is detected using the cuff pressures detected by any one of the pressure sensors. In this case, the representative value is used to exclude extremely high and low cuff pressure values ​​within the cuff pressure values ​​detected by a pressure sensor in time series. Accordingly, cuff pressures related to stabilization detection, that is, cuff pressure values ​​to be used to detect differences, can be selectively extracted based on the representative value from the cuff pressure values ​​output by a pressure sensor at multiple time points.Consequently, this allows to improve the precision in stabilization detection. (Pressure sensor abnormality detection)

[0072] In the transition period described above, in the case where the stabilization of the cuff pressure is detected, the pressure build-up end detection unit 133 compares each of the difference values ​​within the range of the threshold value α with the reference value β (see Fig. 7A and Fig. 7B) read from the memory 43. Note that in the case where stabilization is detected using only one pressure sensor, when abnormality detection is performed, values ​​from both pressure sensors are detected and used for comparison. Based on the comparison result in the case where it is detected that all difference values ​​exceed the reference value β, it is detected that an abnormality has occurred in at least one of the first pressure sensor 321 and the second pressure sensor 322. Here, the reference value β indicates a difference threshold for detecting an abnormality such as a malfunction of the first and second pressure sensors 321 and 322.

[0073] Here it is assumed that the thresholds α and β were previously detected by experiment or similar. Re-pressurization and re-detection

[0074] In the pressure reduction process (before blood pressure calculation) and the blood pressure increase process, which are not in the transition period, in the case where the stabilization detection unit 1134 detects that the cuff pressure has not stabilized due to, for example, a body movement of the measured person, when the pressure sensor abnormality detection is to be performed, the pressure adjustment unit 111 starts rotating (driving) the pump 51 via the pump drive circuit 53 in response to the detection signal. Accordingly, the cuff pressure is increased again. After that, the stabilization detection unit 1134 performs the stability detection again. Specifically, in the case where the amplitude fluctuation (see the broken line PX in Fig. 5), which results from the body movement, at the cuff pressure P3 is detected in the pressure reduction process (before the blood pressure calculation), the re-pressure build-up is carried out and then the cuff pressure stability detection is carried out again.

[0075] Even if the pressure sensor normality detection is to be performed after the blood pressure calculation in the pressure reduction process is completed, in the case where the stability detection unit 1134 has detected that the cuff pressure has not stabilized due to, for example, a body movement of the measured person, the pressure adjustment unit 111 reduces the cuff pressure to a predetermined pressure in response to the detection signal by opening the closed valve 52 via the valve drive circuit 54. Thereafter, the stability detection unit 1134 performs the cuff pressure stability detection again. Specifically, in the case where the amplitude fluctuation (see broken line PY in Fig. 5), which results from the body movement, is detected at the time P4 in the pressure build-up process (after the blood pressure calculation), the pressure reduction is performed and then the cuff pressure stability detection is performed again.

[0076] Note that although repressurization and re-detection are performed to perform stability detection again in the above description, if stabilization is not detected, this fact can be displayed by the display unit 40 or the like to prevent body movement. This allows a message to be presented to prompt the person being measured to remain still. (Blood pressure measurement processing)

[0077] The following describes the blood pressure measurement processing in different cases of timing, according to which pressure sensor normality detection is performed.

[0078] Pressure sensor abnormality detection at the end of the pressure build-up process

[0079] The following is a description of a procedure to perform pressure sensor abnormality detection in the transition period described above with reference to Fig. 9 to execute.

[0080] First, when the measuring person operates (presses) the power supply switch 41A (step ST1), the CPU 100 initializes a working memory which is not shown (step ST2).

[0081] Next, the first and second pressure sensors 321 and 322 are set to 0 mmHg (step ST3).

[0082] Here the person taking the measurement wraps the cuff 20 around the measuring location as in Fig. 1. After the cuff 20 is wrapped around the measurement site, when the measured person operates (presses) the measurement switch 41B (step ST4), the pressure setting unit 111 outputs control signals to the pump drive circuit 53 and the valve drive circuit 54. Based on the control signals, the pump drive circuit 53 and the valve drive circuit 54 close the valve 52 and then drive the pump 51. Accordingly, the setting unit 111 compares the cuff pressure detected by the first pressure sensor 321 with the pressure build-up end pressure PE read from the memory 42, and gradually increases the cuff pressure to the pressure build-up end pressure PE based on the comparison results (steps ST5 and ST6).

[0083] After the cuff pressure has been increased to the pressure build-up end pressure Pe ("≥PE" in step ST6), the pressure adjustment unit 111 sends control signals to the pump drive circuit 53 and the valve drive circuit 54. Based on the control signals, the pump drive circuit 53 and the valve drive circuit 54 stop the pump 51 and close the valve 52 (step ST7). Accordingly, the cuff pressure is maintained constant during the transition period.

[0084] Next, the stability detection unit 1134 detects whether the cuff pressure has stabilized as described above during the transition period. If it has been detected that the cuff pressure has not stabilized and the pressure build-up end detection unit 1133 has detected that a pressure sensor abnormality has occurred (step ST8a and YES in step ST9), the pressure adjustment unit 111 fully opens the valve 52 via the valve drive circuit 54 (step ST10). Accordingly, the air is rapidly released from the cuff 20, and this series of processing is terminated.

[0085] While the cuff pressure is stable, if the pressure build-up end detecting unit 1133 determines that a pressure sensor abnormality has not occurred (NO in step ST9), the blood pressure is calculated in the pressure reduction process.

[0086] Specifically, the pressure adjusting unit 111 gradually opens the valve 52 via the valve driving circuit 54. The cuff pressure therefore gradually decreases (step ST11).

[0087] In this pressure reduction process, the blood pressure calculation unit 112 detects the pulse wave amplitude information based on the frequency signals output by the first oscillation circuit 331 and the second oscillation circuit 332, that is, based on the cuff pressure signals detected by the first pressure sensor 321 and the second pressure sensor 322, and performs a predetermined arithmetic operation on the detected pulse wave amplitude information. The systolic blood pressure SYS and the diastolic blood pressure DIA are calculated with this arithmetic operation (steps ST12 and ST13). The pulse wave amplitude information represents a volume change distribution with respect to the artery at the measurement site and is included in the detected cuff pressure signals.

[0088] When the systolic blood pressure SYS and the diastolic blood pressure DIA are calculated and the blood pressure values ​​are determined (YES in step ST13), the pressure setting unit 111 fully opens the valve 52 via the valve driving circuit 54. Accordingly, the air in the cuff 20 is quickly released (step ST14).

[0089] The blood pressure data calculated by the blood pressure calculation unit 112 is output to the display processing unit 115 and the recorder 114. The display processing unit 115 receives an input of the blood pressure data and displays the input blood pressure data on the display unit 40 (step ST15). Also, the recorder 114 receives an input of the blood pressure data and stores the input blood pressure data in a predetermined storage area of ​​the memory 43 along with the time data input from the timer 45 (step ST16).

[0090] Note that the blood pressure calculation unit 112 can also calculate a pulse rate based on the detected pulse wave amplitude information. The calculated pulse rate is displayed on the display unit 40 by the display processing unit 115 and stored in the memory 43 by the recording unit 114 in conjunction with the blood pressure data.

[0091] Even if it is determined that a sensor abnormality has occurred (YES in step ST9), the blood pressure is not calculated, and therefore the message "Sensor Malfunction" may be displayed on the display unit 40. Based on the displayed message, the person taking the measurement can confirm that the blood pressure was not calculated due to a sensor abnormality.

[0092] In the flow chart of the Fig. 9, in the case where a pressure sensor abnormality is detected, the blood pressure measurement processing is stopped (the blood pressure calculation is not executed), however, a configuration is possible in which the blood pressure measurement processing continues instead of being stopped, and the message "Sensor Failure" is displayed on the display unit 40 after the blood pressure measurement.

[0093] Pressure sensor abnormality detection at cuff pressure P1 in Fig. 5

[0094] The following is a description of a procedure to perform pressure sensor abnormality detection at a cuff pressure (cuff pressure P1 in Fig. 5) which is lower than the diastolic blood pressure DIA in the pressure build-up process, with reference to Fig. 10. It is assumed that the value of cuff pressure P1 (first pressure value) is previously stored in the memory 42.

[0095] In Fig. 10, the processing of steps ST1 to ST4 is carried out in the same way as the corresponding steps in Fig. 9. Next, the pressure adjustment unit 111 compares the cuff pressure detected by the first pressure sensor 321 with the cuff pressure P1 read from the memory 42, and continues to perform pressure buildup by rotating the pump 51 until, based on the comparison results, the cuff pressure is greater than or equal to the first pressure value (i.e., the value of the cuff pressure P1) ("≥ 1st PV" in step ST6a). After that, the pump 51 is stopped. The cuff pressure is therefore kept constant (step ST7).

[0096] Next, the stabilization detection unit 1134 detects whether the cuff pressure has stabilized, as described above. If the cuff pressure has not stabilized, and the pressure buildup detection unit 1131 has detected that a pressure sensor abnormality has occurred (step ST8 and YES in step ST9), the pressure adjustment unit 111 fully opens the valve 52 via the valve drive circuit 54 (step ST10). Accordingly, air is quickly released from the cuff 20, and the sequence of this processing ends. In this way, the blood pressure measurement processing is stopped in the case where a pressure sensor abnormality has been detected. Note that the details of the abnormality detection processing (step ST8) will be described later.

[0097] While the cuff pressure is stable, if the pressure build-up detecting unit 1131 determines that a pressure sensor abnormality has not occurred (NO in step ST9), the pressure build-up process continues until the cuff pressure reaches the pressure build-up end pressure PE, and the blood pressure is calculated during this time (steps ST11a and ST12).

[0098] If the systolic blood pressure SYS and the diastolic blood pressure DIA have been determined (YES in step ST13), the processing is carried out in the same manner as the processing of steps ST14 to ST16 in Fig. 9.

[0099] Pressure sensor abnormality detection at cuff pressure P2 in Fig. 5

[0100] The following is a description of a procedure to perform pressure sensor abnormality detection at a cuff pressure (cuff pressure P2 in Fig. 5) which is higher than the systolic blood pressure SYS in the pressure build-up process, with reference to Fig. 11. It is assumed that the value of cuff pressure P2 (second pressure value) is previously stored in the memory 42.

[0101] In Fig. 11, the processing of steps ST1 to ST4 is carried out in the same way as the corresponding steps in Fig. 9. Next, the pump 51 rotates to increase the cuff pressure, and the blood pressure calculation is performed in the pressure build-up process (steps ST4a to ST4c). When the blood pressure values ​​(diastolic blood pressure DIA and systolic blood pressure SYS) have been determined, the pressure setting unit 111 compares the cuff pressure detected by the first pressure sensor 321 with the cuff pressure P2 read from the memory 42 and continues to perform the pressure build-up by rotating the pump 51 until, based on the comparison results, it is determined that the cuff pressure is greater than or equal to the second pressure value (i.e., the value of the cuff pressure P2) ("≥ 2nd PV" in step ST6b). Thereafter, the pump 51 is stopped, and the cuff pressure is kept constant (step ST7).

[0102] Next, the stability detection unit 1134 detects whether the cuff pressure has stabilized, as described above. If it has been detected that the cuff pressure has not stabilized and the pressure buildup detection unit 1131 has detected that a pressure sensor abnormality has occurred (step ST8 and YES in step ST9), the pressure adjustment unit 111 fully opens the valve 52 via the valve drive circuit 54 (step ST10). Accordingly, air is quickly released from the cuff 20, and the sequence of processing steps ends.

[0103] While the cuff pressure is stable, if the pressure build-up detecting unit 1131 determines that a pressure sensor abnormality has not occurred (NO in step ST9), the processing is performed in the same manner as the processing of steps ST14 to ST16 in Fig. 9 carried out.

[0104] In the case where the abnormality detection is performed at the cuff pressures P1 and P2, an abnormality can be detected in both the pressure increase process and the pressure decrease process.

[0105] Pressure sensor abnormality detection at cuff pressure P3 in Fig. 5

[0106] The following is a description of a procedure to perform pressure sensor abnormality detection at a cuff pressure (cuff pressure P3 in Fig. 5) which is greater than the systolic blood pressure SYS in the pressure reduction process, with reference to Fig. 12. It is assumed that the value of cuff pressure P3 is previously stored in the memory 42.

[0107] In Fig. 12, the processing of steps ST1 to ST7 is carried out in the same way as the corresponding steps in Fig. 9. Next, while the pump 51 is stopped, the valve 52 is opened, and a transition is made to the pressure reduction process in which the cuff pressure is gradually reduced. In the pressure reduction process, the pressure setting unit 111 compares the cuff pressure detected by the first pressure sensor 321 with the cuff pressure P3 read from the memory 42, and continues to perform the pressure reduction while determining, based on the comparison results, that the cuff pressure is greater than the third pressure value (i.e., the value of the cuff pressure P3), and when it is determined that the cuff pressure is less than or equal to the third pressure value ("≤ 3rd PV" in step ST11a), the valve 52 closes, and the cuff pressure is kept constant (step ST11b).

[0108] Next, the stabilization detection unit 1134 detects whether the cuff pressure has stabilized, as described above. If the cuff pressure has not stabilized, and the pressure reduction detection unit 1132 has detected that a pressure sensor abnormality has occurred (step ST11c and YES in step ST11d), the pressure adjustment unit 111 fully opens the valve 52 via the valve drive circuit 54 (step ST17). Accordingly, air is quickly released from the cuff 20, and this series of processing ends. In this way, the blood pressure measurement processing is stopped in the case where a pressure sensor abnormality has been detected. Note that the details of the abnormality detection processing (step ST11c) will be described later.

[0109] While the cuff pressure is stable, if the pressure reduction detecting unit 1132 determines that a pressure sensor abnormality has not occurred (NO in step ST11d), the pressure reduction process in which the deflation gradually progresses continues, and the blood pressure is calculated during this time (steps ST11e and ST12).

[0110] If the systolic blood pressure SYS and the diastolic blood pressure DIA have been determined (YES in step ST13), the processing is carried out in the same manner as in the processing of steps ST14 to ST16 in Fig. 9 carried out.

[0111] Pressure sensor abnormality detection at cuff pressure P4 in Fig. 5

[0112] The following is a description of a procedure to perform pressure sensor abnormality detection at a cuff pressure (cuff pressure P4 in Fig. 5) which is lower than the diastolic blood pressure DIA in the pressure reduction process, with reference to Fig. 13. It is assumed that the value of cuff pressure P4 is previously stored in the memory 42.

[0113] In Fig. 13, the processing of steps ST1 to ST7 is carried out in the same way as the corresponding steps in Fig. 12. Next, the valve 52 is opened while the pump 51 is stopped, thus transitioning to the pressure reduction process. The blood pressure calculation is performed in the pressure reduction process (steps ST7a to ST7c). When the blood pressure values ​​(diastolic blood pressure DIA and systolic blood pressure SYS) have been determined, the pressure adjustment unit 111 compares the cuff pressure detected by the first pressure sensor 321 with the cuff pressure P4 read from the memory 42 and performs pressure reduction until, based on the comparison results, the cuff pressure is less than or equal to the fourth pressure value (i.e., the value of the cuff pressure P4) ("≤ 4th PV" in step ST11a). Thereafter, the valve 52 is closed, and the cuff pressure is maintained at a constant pressure (step ST11b).

[0114] Next, the stability detection unit 1134 detects whether the cuff pressure has stabilized, as described above. If the cuff pressure has not stabilized and the pressure reduction detection unit 1132 detects that a pressure sensor abnormality has occurred (step ST11c and YES in step ST11d), the pressure adjustment unit 111 fully opens the valve 52 via the valve drive circuit 54 (step ST17). Accordingly, air is quickly released from the cuff 20, and this series of processing ends.

[0115] While the cuff pressure is stable, if the pressure reduction detecting unit 1132 determines that a pressure sensor abnormality has not occurred (NO in step ST11d), the processing is carried out in the same manner as the processing of steps ST14 to ST16 in Fig. 9.

[0116] In this way, the pressure sensor abnormality detection is carried out at least at one or more times within the time lapses in the pressure build-up process, the transition period and the pressure reduction process in the blood pressure measurement (where the times corresponding to the cuff pressures P1 to P4 in Fig. 5), thus eliminating the need to provide a separate abnormality detection step.

[0117] Also, in both the pressure build-up process and the pressure reduction process, the abnormality detection is performed while keeping the cuff pressure constant, thus enabling high detection precision to be obtained.

[0118] Fig. Fig. 14 is a flowchart of the processing of sensor abnormality detection (step ST8 and ST11c) which are performed in the pressure increase process and the pressure decrease process (before the blood pressure value calculation), that is, at the cuff pressures P1, P2 and P3 in Fig. 5.

[0119] First, the stabilization detection unit 1134 detects the cuff pressure values ​​from the first and second pressure sensors 321 and 322 at a predetermined interval, that is, at multiple time points (steps ST20 and ST21). A difference between the pressures detected by the pressure sensors is then detected for each time lapse, and the detected differences are compared (step ST23). A determination is then made as to whether the difference between the differences obtained as a result of the comparison falls within the range of the threshold value α (step ST25).

[0120] As a result of the determination, in the case where it is detected that the difference between the differences is a value falling within the range of the threshold value α (YES in step ST25), as shown in Fig. As shown in Figure 7b, the abnormality detection unit 137 detects whether each pressure difference is greater than the reference value β. If a pressure difference greater than the reference value β is detected, it is detected that a pressure sensor abnormality has occurred; otherwise, it is detected that a pressure sensor abnormality has not occurred.

[0121] On the other hand, in the case where it is detected that the difference between the differences is not a value falling within the range of the threshold value α (NO in step ST25), the repressurization request unit 1135 outputs a repressurization request signal to the pressure setting unit 111 (step ST29). In response to the request, the pressure setting unit 111 causes the pump 51 to rotate so as to raise the cuff pressure to a predetermined pressure (step ST31). When the cuff pressure reaches the predetermined pressure, the pump 51 stops and the valve 52 closes (step ST33). After such repressurization, the procedure returns to the processing of step ST20, and the subsequent processing is repeated.

[0122] In this way, in the case where the pressure sensor abnormality detection cannot be performed because the cuff pressure stabilization period cannot be detected due to body movement, measurement of the person's pulse, or the like, the cuff pressure can be increased or reduced again so as to achieve a state in which a disturbance such as body movement or measurement of the person's pulse can be prevented, and then the cuff pressure stability detection and the pressure sensor abnormality detection can be performed again.

[0123] Fig. Fig. 15 is a flowchart of the sensor abnormality detection processing (step ST11c) which is performed in the pressure reduction process (after the blood pressure value calculation), that is, at the cuff pressure P4 in Fig. 5.

[0124] First, the stabilization detecting unit 1134 and the abnormality detecting unit 1137 perform the processing of steps ST20 to ST27 similarly to Fig. 14 through.

[0125] In the case where it is detected that the difference between the differences is not a value falling within the range of the threshold value α (NO in step ST25), as in Fig. As shown in Figure 7B, the re-detecting unit 1136 outputs a pressure reduction request signal to the pressure adjustment unit 111 (step ST35). In response to the request, the pressure adjustment unit 111 opens the valve 52 so as to reduce the cuff pressure to a predetermined pressure (step ST35). When the cuff pressure reaches the predetermined pressure, the valve 52 closes (ST37). After such pressure reduction, the procedure returns to the processing of step ST20, and the subsequent processing is repeated.

[0126] In this way, in the case where the pressure sensor abnormality detection cannot be performed because the cuff pressure stability period cannot be detected due to a body movement, the measurement of a person's pulse, or the like, the cuff pressure can be reduced so as to achieve a state in which a disturbance such as a body movement or the measurement of a person's pulse can be prevented, and thereafter the cuff pressure stability detection and the pressure sensor abnormality detection can be performed again. Display examples

[0127] Fig. 16 shows an example of the display of pressure sensor abnormality detection results on the display unit 40. Although calculated blood pressure values ​​are not stored in the memory 43, in the case where a pressure sensor abnormality is detected in the flowcharts described above, the calculated blood pressure values ​​may be stored together with the abnormality detection result. In this case, the pressure sensor abnormality detection result is displayed together with the blood pressure measurement values.

[0128] In Fig. 16, the display processing unit 115 switches the display mode based on the detection result of the sensor abnormality detection unit 113. Specifically, when the first and second pressure sensors 321 and 322 are operating normally, the display of the letters "ERR" is turned off, and only the display of the letters "OK" is turned on. When the detection result indicates that an abnormality has occurred, the display of the letters "OK" is turned off, and the display of the letters "ERR" is turned on. This allows the user to be informed that the device is operating normally when the first and second pressure sensors 321 and 322 are operating normally.

[0129] A warning mode, such as the following, is also possible. Specifically, when measurement starts, the letters indicating normal operation ("OK") are displayed, or a lamp is illuminated. Then, if a pressure sensor abnormality is detected, a warning of the abnormality can be given by displaying the letters or flashing the lamp. Accordingly, the warning mode when measurement starts is a mode for issuing a warning or notification regarding normal operation, and the warning mode changes to an abnormality warning mode when an abnormality is detected.

[0130] The following are displayed on the display unit 40: the measured time data 402 obtained by the measurement performed by the timer 45; the systolic blood pressure SYS data 403, the diastolic blood pressure DIA data 404, and the pulse rate data 405, which are the results of the blood pressure measurement; and "ERR" / "OK" indicating the result of the pressure sensor abnormality detection.

[0131] By checking such a display, the user can know when to request a pressure sensor correction from the manufacturer. This prevents a blood pressure measurement from being taken without the user realizing that a pressure sensor abnormality has occurred, and improves the reliability of the blood pressure readings.

[0132] Note that although the electronic blood pressure monitor 1 is described in the embodiment as a stationary electronic blood pressure monitor in which the cuff 20 is wrapped around the upper arm area, the present invention is not limited thereto. For example, the present invention can be similarly applied to a wrist-wrapped electronic blood pressure monitor in which the cuff 20 and the main unit 10 are integrally configured, and the cuff 20 is wrapped around the wrist, as shown in FIG. Fig. 17 is shown.

[0133] Thus, the embodiment of the invention described above is to be considered in all respects only as illustrative and not restrictive. The technical scope of the invention is defined by the scope of the claims, and all modifications that come within the meaning and range of equivalence of the claims are intended to be embraced by the scope of the invention. List of references 1 electronic blood pressure monitor 10 Main unit 20 cuff 21 Air bellows 31 Air hose 40 display unit 41 Control unit 41A power supply switch 41B measuring switch 41B measuring switch 41D memory switch 42 processing memory 43 Data storage device 44 Power supply 45 time element 51 Pump 52 Valve 53 Pump driver circuit 54 Valve driver circuit 111 Pressure adjustment unit 112 Blood pressure calculation unit 113 Sensor abnormality detection unit 137 Abnormality Detection Unit 114 Recording unit 115 Display processing unit 133 Pressure build-up end detection unit 321 first pressure sensor 322 second pressure sensor 331 first oscillation circuit 332 second oscillation circuit 402 measured time data 403 systolic blood pressure SYS data 404 diastolic blood pressure DIA data 404 diastolic blood pressure DIA data 405 heart rate data 431 readout data 600 pulse wave amplitude envelopes 1131 Pressure build-up detection unit 1132 Pressure reduction detection unit 1133 Pressure build-up end detection unit 1134 Stabilization detection unit 1135 Request Unit 1136 Re-detection unit 1137 Abnormality Detection Unit

Claims

[1] Electronic blood pressure monitor (1), which comprises: a cuff (20) which can be worn at a measuring location; a pressure adjustment unit (51, 52) which adjusts the pressure within the cuff (20) by increasing or decreasing pressure; a pressure detection unit including a plurality of pressure sensors (321, 322) and configured to detect the cuff pressure within the cuff (20) based on the pressure information output from the plurality of pressure sensors; a blood pressure calculation unit (112) which calculates a blood pressure based on the change in cuff pressure, which is detected by the pressure detecting unit at a time of blood pressure measurement; a maintenance unit (111) which maintains the cuff pressure at a predetermined pressure at the time of blood pressure measurement; and an abnormality detection unit (113) which, in a state in which the maintenance unit maintains the cuff pressure at a predetermined pressure, detects whether an abnormality has occurred in at least one of the plurality of pressure sensors (321, 322), based on the pressure information output by the plurality of pressure sensors (321, 322). [2] The electronic blood pressure monitor (1) according to claim 1, wherein the blood pressure measurement includes a pressure build-up process in which pressure is built up in the cuff (20) by the pressure setting unit (111) after the blood pressure measurement is started, a pressure reduction process in which the pressure in the cuff (20) is reduced, and a transition period from after the pressure build-up process is finished until when the pressure reduction process is started, and the maintaining unit (1) maintains the pressure applied in the cuff (20) at the predetermined pressure in at least one of the pressure build-up process, the pressure reduction process, and the transition period. [3] An electronic blood pressure monitor (1) according to claim 2, wherein the predetermined pressure indicates the cuff pressure at the time when the pressure build-up process has been completed. [4] The electronic blood pressure monitor (1) according to claim 1, wherein the abnormality detection unit (113) includes: a stability detection unit (1134) which detects whether the cuff pressure is maintained at the predetermined pressure based on the pressure information output from the plurality of pressure sensors (321, 322), and in a case where the stability detecting unit (1134) has detected that the cuff pressure is maintained at the predetermined pressure, the abnormality detecting unit (113) detects whether an abnormality has occurred in at least one of the plurality of pressure sensors (321, 322) based on the pressure information output from the plurality of pressure sensors (321, 322). [5] The electronic blood pressure monitor (1) according to claim 4, wherein the abnormality detection unit (113) detects, with reference to the pressure information outputted in time series from one of the plurality of pressure sensors (321, 322), a difference in the pressure information at a plurality of time points, and detects whether the cuff pressure is maintained at the predetermined pressure based on the detected difference. [6] The electronic blood pressure monitor (1) according to claim 5, wherein the stability detecting unit (1134) detects representative pressure information based on the pressure information output by one of the pressure sensors (321, 322) at the plurality of times, and, based on the representative pressure information, extracts the pressure information for detecting the difference from the pressure information at the plurality of times output by at least one of the plurality of pressure sensors (321, 322). [7] The electronic blood pressure monitor (1) according to claim 4, wherein, based on the pressure information at a plurality of time points output by the plurality of pressure sensors (321, 322) in time series, the stability detecting unit (1134) detects a difference in the pressure information at each of the time points, and detects whether the cuff pressure is maintained at the predetermined pressure based on a difference between the detected differences. [8] The electronic blood pressure monitor (1) according to claim 7, wherein the stability detecting unit (1134) detects representative pressure information based on the pressure information output by the plurality of pressure sensors (321, 322) at the plurality of times, and, based on the representative pressure information, extracts the pressure information for detecting the difference from the pressure information at the plurality of times output by the plurality of pressure sensors (321, 322). [9] The electronic blood pressure monitor (1) according to claim 1, wherein the blood pressure measurement is stopped in a case where the abnormality detecting unit (113) has detected the occurrence of an abnormality in at least one of the plurality of pressure sensors (321, 322). [10] Electronic blood pressure monitor (1) according to claim 1, further comprising: a storage unit, wherein each time the abnormality detection unit (113) detects whether an abnormality has occurred in at least one of the plurality of pressure sensors (321, 322), the storage unit stores a result of the detection, and when the blood pressure measurement is to be started, in a case where a determination has been made that the result of detection read out from the storage unit indicates that an abnormality has occurred, the blood pressure measurement is stopped, and the result of detection read out is output. [11] The electronic blood pressure monitor (1) according to claim 1, wherein the electronic blood pressure monitor outputs a result of detection performed by the abnormality detection unit (113). [12] The electronic blood pressure monitor (1) according to claim 1, wherein, in a case where the abnormality detecting unit (113) has detected that an abnormality has occurred in at least one of the plurality of pressure sensors (321, 322), the blood pressure measurement is terminated, and thereafter, a result of the detection performed by the abnormality detecting unit (113) is outputted. [13] Electronic blood pressure monitor (1) according to claim 1, further comprising: a data storage unit which stores blood pressure data indicating the blood pressure measured by the blood pressure calculation unit (112) and stores a result of the detection performed by the abnormality detection unit (113) together with the blood pressure data, where within the blood pressure data in the data storage unit, the blood pressure data corresponding to a detection result indicating the occurrence of an abnormality are excluded from the blood pressure data to be used for calculating statistics. [14] An electronic blood pressure monitor (1) according to claim 4, wherein in a case where the stability detecting unit (1134) has not detected that the cuff pressure is maintained at a predetermined pressure, a warning of this fact is given. [15] The electronic blood pressure monitor (1) according to claim 4, wherein in a case where the stability detecting unit (1134) has not detected that the cuff pressure is maintained at a predetermined pressure, the pressure adjusting unit (111) pressurizes the cuff (20) and thereafter the stability detecting unit (1134) again detects whether the cuff pressure is maintained at a predetermined pressure.

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