Blood pressure monitor, method for controlling the blood pressure monitor and program

Abstract

Blood pressure measuring device (1) which measures blood pressure by means of tonometry, wherein the blood pressure measuring device (1) has: a measuring device (11) which includes a plurality of pressure sensors (110) and serves to measure the blood pressure information for each heartbeat at a measuring location; an arrangement state inference device (23) for extracting a feature quantity from an output signal waveform for each of the pressure sensors (110) for each heartbeat, and deriving or inferring an arrangement state of the measuring device (11) relative to an artery, which is the object being measured, based on a distribution profile of the values ​​of the feature quantity for the plurality of pressure sensors (110); and a reliability calculation device (24) for calculating the reliability of the blood pressure information measured by the measuring device (11) based on the determined or inferred arrangement state, wherein the arrangement state inference device (23) extracts from the output signal waveform of each of the pressure sensors (110) for each heartbeat a difference value between a maximum value and a minimum value in the output signal waveform and / or the minimum value as the feature size and estimates the arrangement state of the measuring device (11) based on a distribution profile of the difference value for the plurality of pressure sensors (110) and / or a distribution profile of the minimum value, wherein the measuring device (11) has at least one sensor array which is composed of a plurality of pressure sensors (110) arranged side by side in a direction which intersects the artery during the measurement, wherein the arrangement state includes a slope of a lateral direction which indicates the slope in a direction perpendicular to a direction of the extension of the artery relative to a reference state which is an orientation or alignment suitable for measurement, and the arrangement state inference device (23) determines or infers the slope of the lateral direction based on a slope in the distribution profile of the minimum value.

Description

Technical area

[0001] The present invention relates to a device for measuring blood pressure and a method for controlling the same, and relates, more specifically, to a device for performing blood pressure measurement by means of tonometry. Background of the state of the art

[0002] One tonometry method for measuring blood pressure is known in which an artery near the body surface, such as a radial artery, is compressed to such an extent that a flattened section is formed within the artery. This allows for the equilibrium of intra-arterial and external pressures, and the blood pressure is then measured non-invasively using a pressure sensor. This method makes it possible to obtain a blood pressure reading for each heartbeat non-invasively.

[0003] When blood pressure measurement is performed using tonometry, the pressure sensor must be positioned precisely above an artery. Accordingly, real-world devices are provided with numerous micro-pressure sensors. The most suitable output signal, corresponding to the blood pressure waveform, is selected from among the output signals of the sensor groups, and the blood pressure is measured based on this selected signal. For example, patent literature 1 discloses a method for selecting the most suitable output signal. List of citations

[0004] Patent Literature 1: JP 2004-222847 A

[0005] WO 2013 / 068 955 A1 describes a tonometer structure for the continuous monitoring of a patient's arterial pressure over a specific period. The tonometer structure includes a carrier body to which a sensing unit is attached. During use, the sensing unit comes into contact with the patient's skin near an artery (52) and features several piezoresistive pressure sensors. A measurement signal is assigned to a sphygmic wave with a specific amplitude. A reference sensor and a limit sensor provide signals from which it can be inferred if random movement is occurring.

[0006] DE 603 ​​06 093 T2 describes a pulse wave detection device comprising a pressure sensor array on which several pressure sensors are arranged. When used on a patient, a pressure application device generates pressure against an artery. A sensor selection section allows the user to choose which pressure sensor applies pressure to the artery. A pulse wave detection section detects pulse waves, which are evaluated using pressure information across the selected pressure sensor(s). The sensor selection section can also be used to extract a DC voltage component from the voltage signal of the pressure sensor. Summary of the invention: Technical problem

[0007] Patent literature 1 describes the following most suitable output signal selection method. Specifically, a sensor array has a pressure-sensitive surface on which many pressure sensors are attached. The sensor array is pressed against the body surface, and many voltage signals indicating pressure information are received simultaneously by the pressure sensors when pulse wave detection is performed. A CPU extracts a DC component from each of the voltage signals, indicating a pressure component generated by a solid object, and specifies the pressure sensors to be placed above the solid object based on these extracted DC components.The pressure sensors, unlike the specified pressure sensors which are placed above a solid object, are then selected as candidates for the pressure sensors which are placed above an artery, and a pulse wave which is generated by an artery is detected based on the pressure information output signal by the selected pressure sensors.

[0008] According to this type of technique, in cases where the measured value is significantly affected by pressure sensors located on solid objects other than an artery, it is possible to specify the sensors that are in an unsuitable arrangement and to exclude such sensors from the candidates for selecting the most suitable output signal value.

[0009] However, the conventional technique described above has a problem: even if the output signal is obtained under conditions that negatively affect data analysis, such as the case of displacement in the direction in which the artery is compressed (the sensor group is inclined relative to the compressed surface), such a case is treated in the same way as the case in which the sensor group is appropriately arranged.

[0010] In view of the circumstances described above, it is an object of the present invention to provide a technique for calculating the reliability of the blood pressure information measured in a tonometry-type blood pressure measurement method. Solution to the problem

[0011] To solve the aforementioned problem, the present invention employs configurations such as the following.

[0012] A blood pressure measuring device according to the present invention is a blood pressure measuring device which measures blood pressure by means of tonometry, wherein the blood pressure measuring device comprises: a measuring device which includes a plurality of pressure sensors and serves for measuring the blood pressure information for each heartbeat in a measurement object; a conclusion device of an arrangement state for extracting a feature quantity from an output signal waveform of each of the pressure sensors for each heartbeat, and determining or concluding an arrangement state of the measuring element relative to an artery which is the measurement object, based on a distribution profile of values ​​of the feature quantity for the plurality of pressure sensors; and a calculation element for a reliability in order to calculate a reliability of the blood pressure information which is measured by the measuring element, based on the introduced arrangement state.

[0013] According to this configuration, it is possible to obtain reliability regarding the blood pressure measurement information, and the blood pressure information obtained when the measuring element is in an unsuitable state (i.e., a measurement that has low reliability) can be prevented from being treated similarly to blood pressure information obtained when the measuring element is in a suitable arrangement state (i.e., a measurement that has high reliability).

[0014] Here, the arrangement state input element extracts from the output signal waveform for each of the pressure sensors for each heartbeat a difference value between a maximum value and a minimum value in the output signal waveform and / or the minimum value as the feature size and estimates the arrangement state of the measuring element based on a distribution profile of the difference value for the multitude of blood pressure sensors and / or a distribution profile of the minimum value.

[0015] The measuring device also has at least one sensor field, which is composed of a large number of pressure sensors that are mounted side by side in a direction that intersects the artery during the measurement.

[0016] In accordance with this configuration, which has a group of pressure sensors in a predetermined arrangement, the distribution profile of the feature size can be understood as including the predetermined arrangement, and the arrangement state can be efficiently introduced or determined.

[0017] The arrangement state also includes a pressure magnitude, which indicates the magnitude of the force that the sensor field applies to the artery, and the inference device of the initial state determines or infers the pressure magnitude based on a difference between a peak value and a low value in the distribution profile of the difference value and / or the peak value in the distribution profile of the difference value.

[0018] According to this configuration, in which the arrangement state includes the pressure magnitude, it is possible, in the case where the blood pressure information is measured in a state where the magnitude of the force applied to the artery by the sensor field is unsuitable, to obtain a reliability of the blood pressure information that reflects or reproduces this state.

[0019] Furthermore, the arrangement state can include a lateral inclination, which indicates an inclination in a direction perpendicular to a direction of artery extension relative to a reference state, which is an orientation suitable for measurement, and the initial state insertion element can determine or infer the lateral inclination based on an inclination in the distribution profile of the minimum value.

[0020] According to this configuration, in which the arrangement state includes the inclination of the lateral direction, it is possible, in the case where the blood pressure information is measured in a state in which the measuring element is inclined in a direction perpendicular to the expansion direction of the artery relative to the suitable state, to obtain a reliability of the blood pressure information that reflects this state.

[0021] Furthermore, the arrangement state can include a shift in the lateral direction, which indicates the shift in a direction perpendicular to a direction of artery extension, relative to a reference state, which is an orientation suitable for measurement, and the inference device of the arrangement state can determine or infer the shift in the lateral direction based on a position of a peak value in the distribution profile of the difference value.

[0022] In accordance with this configuration, in which the arrangement state includes the shift of the lateral direction, it is possible, in the case where the blood pressure information is measured in a state in which the measuring element is inclined in a direction perpendicular to the expansion direction of the artery relative to the suitable state, to obtain a reliability of the blood pressure information that reflects this state.

[0023] Furthermore, the measuring element can include a first sensor field and a second sensor field arranged parallel to each other; the arrangement state can include an inclination of the arterial direction, which indicates an inclination in a direction parallel to a direction of arterial extension relative to a reference state, which is an orientation suitable for measurement; and the inference device of the arrangement state can determine or infer the inclination of the arterial direction based on a difference between a peak value and a lowest value in the distribution profile of the difference value for both the first sensor field and the second sensor field.

[0024] In this way, because the sensor group, which has a predefined arrangement, is provided in two parallel rows, it is possible to efficiently estimate a large number of arrangement states of the measuring device. Furthermore, because the arrangement state includes the inclination of the arterial direction of the measuring element in the case where the blood pressure information is measured in a state where the measuring device is inclined in a direction parallel to the artery's expansion direction relative to the appropriate state, it is possible to obtain a reliable blood pressure information that accurately reflects this state.

[0025] Furthermore, the measuring device can include a first sensor field and a second sensor field arranged parallel to each other; the arrangement state can include a shift in the arterial direction, indicating a shift in a direction parallel to a direction of arterial extension relative to a reference state, which is an orientation suitable for measurement; and the arrangement state inference device can determine or infer the shift in the arterial direction based on a difference between the peak values ​​in the distribution profiles of the difference values ​​of the first sensor field and the second sensor field.

[0026] In accordance with this configuration, in which the arrangement state includes the displacement of the arterial direction, it is possible, in the case where the blood pressure information is measured in a state in which the measuring device is displaced in a direction parallel to the extension direction of the artery relative to the appropriate state, to obtain a reliability of the blood pressure information that reflects this state.

[0027] Furthermore, the measuring device can include a first sensor field and a second sensor field arranged parallel to each other; the arrangement state can include a rotational displacement, which indicates the rotation of the sensor field in a plane of contact with the object being measured relative to a reference state, which is an orientation suitable for measurement; and the inference device for the arrangement state can determine or infer the rotational displacement based on a difference between the positions of the peak values ​​in the distribution profiles of the difference values ​​of the first sensor field and the second sensor field.

[0028] In accordance with this configuration, in which the arrangement state includes the shift in the direction of rotation, it is possible, in the case where the blood pressure information is measured in a state in which the sensor field is shifted in the direction of rotation in the plane of contact with the object being measured, to obtain a reliability of the blood pressure information that reflects this state.

[0029] The blood pressure measuring device according to the present invention may also include an output device for outputting one or a combination of blood pressure information, the arrangement state and the reliability.

[0030] Depending on the configuration of the output device, the different types of information can be output in a manner suitable for use.

[0031] Furthermore, the output device may be: an image display device or a combination of an image display device for outputting one or a combination of blood pressure information, arrangement status and reliability, using text and / or an image; an audio output device for outputting one or a combination of blood pressure information, arrangement status and reliability, using an audio image; and a communication device for outputting one or a combination of blood pressure information, arrangement status and reliability to another device using wired or wireless communication.

[0032] According to this configuration, it is possible to apply a suitable output method according to the information to be output and the object, and by having many different output devices, it is possible to output the information more effectively.

[0033] The blood pressure measuring device according to the present invention may also include a warning device to output information to the output device indicating an unsuitable arrangement state that causes a reduction in reliability, in a case where the reliability is less than or equal to a previously defined reference value.

[0034] According to this configuration, if the reliability of the blood pressure information is less than or equal to a previously defined reference value, the user of the blood pressure monitor can find out this fact and the cause of it.

[0035] Furthermore, according to the present invention, the blood pressure measuring device may also include a correction instruction device to output to the output device a method for correcting an unsuitable arrangement state which causes a reduction in reliability to a suitable arrangement state, in a case where the reliability is less than or equal to a previously determined reference value.

[0036] In accordance with this configuration, if the reliability of the blood pressure information is less than or equal to the previously specified reference value, the user of the blood pressure monitor can correct the measuring device to a suitable arrangement state according to the correction instructions.

[0037] The blood pressure monitor can also be a portable device according to the present invention, designed to be attached to a wrist.

[0038] According to this configuration, the user of the blood pressure monitor can measure their blood pressure without restricting the body's freedom of movement.

[0039] A method of controlling a blood pressure measuring device according to the present invention comprises: a measurement step of measuring the blood pressure information for each heartbeat in a measurement object by using a measuring device which includes a plurality of pressure sensors; a step of extracting a feature quantity from an output signal waveform of each of the pressure sensors for each heartbeat; a step of determining an arrangement state of the measuring device relative to an artery which is the measurement object, based on a distribution profile of the values ​​of the feature quantity for the plurality of pressure sensors; and a step of calculating a reliability of the blood pressure information which is measured by the measuring device, based on the measured initial state.

[0040] A program according to the present invention causes the steps of the above-described method of controlling a blood pressure monitor to be carried out by the blood pressure monitor.

[0041] Note that the present invention can be understood as a blood pressure monitor which has at least some of the configurations and functions described above. The present invention can also be understood as a method for controlling a blood pressure monitor which includes at least some of the above processing steps, a program for causing a computer (processor) to execute this method, or a computer-readable recording medium on which this program is not transiently recorded. The present invention can be described by combining the configurations and processing steps described above, provided that no technical contradiction arises. Advantageous effects of the invention

[0042] According to the present invention, it is possible to provide a technique for calculating the reliability of the blood pressure information that occurs in a blood pressure measurement method of tonometry. Brief description of the drawings Fig. Figure 1 is a block diagram which represents an overall configuration of a blood pressure measuring device according to a first embodiment of the present invention. Fig. Figure 2 is a drawing showing a state in which a measuring unit of the blood pressure measuring device of the first embodiment is attached to the left wrist of a person being measured by a strap, which is not shown. Fig. Figure 3 is a cross-sectional drawing which schematically shows the structure or construction of the measuring unit of the blood pressure measuring device of the first embodiment and its state during the measurement. Fig. Figure 4 is a drawing showing a side surface of a sensor unit that comes into contact with a body surface in the blood pressure measuring device of the first embodiment. Fig. Figure 5 is a block diagram showing an overall view of a functional configuration of a control unit of the blood pressure measuring device of the first embodiment. Fig. Figure 6 is a flowchart showing an example of the overall process carried out by the blood pressure measuring device of the first embodiment. Fig. Figure 7 is a diagram showing an arterial pressure waveform measured by the pressure sensor. Fig. Figure 8 is a diagram showing an example of a tonogram. Fig. Figure 9 is a drawing showing a state in which the sensor unit of the blood pressure measuring device of the first embodiment is suitably arranged relative to a radial artery, and the shapes of the tonograms in this arrangement state. Fig. Figure 10 is a drawing showing an arrangement state in which the sensor unit of the blood pressure measuring device of the first embodiment is insufficiently pressed, and the shapes of the tonograms in this arrangement state. Fig. Figure 11 is a drawing showing an arrangement state in which the sensor unit of the blood pressure measuring device of the first embodiment is excessively pressed, and the shapes of the tonograms in this arrangement state. Fig. Figure 12 is a drawing showing an arrangement state in which the sensor unit of the blood pressure measuring device of the first embodiment is inclined in the arterial direction, and the shapes of the tonograms in this arrangement state. Fig. Figure 13 is a drawing showing an arrangement state in which the sensor unit of the blood pressure measuring device of the first embodiment is inclined in the lateral direction, and the shapes of the tonograms in this arrangement state. Fig. Figure 14 is a drawing showing an arrangement state in which the sensor unit of the blood pressure measuring device of the first embodiment is shifted in the lateral direction, and the shapes of the tonograms in this arrangement state. Fig. Figure 15 is a drawing showing an arrangement state in which the sensor unit of the blood pressure measuring device of the first embodiment is displaced in the arterial direction, and the shapes of the tonograms in this arrangement state. Fig. Figure 16 is a drawing which shows an arrangement state in which the sensor unit of the blood pressure measuring device of the first embodiment is displaced in the direction of rotation, and the shapes of the tonograms in this arrangement state. Fig. Figure 17 is a flowchart which shows an example of the procedure which is carried out when a conclusion unit of the arrangement state of the blood pressure measuring device of the first embodiment determines or infers the arrangement state of the sensor unit. Fig. 18 is part of a flowchart which shows an example of the process in the step in Fig. 17 “Determine pressure state and inclination of arterial direction” shows. Fig. 19 is another part of a flowchart, which provides an example of the process of step in Fig. 17 “Determine pressure state and inclination of arterial direction” shows. Fig. Figure 20 is a block diagram showing an overall configuration of a blood pressure measuring device according to a second embodiment of the present invention. Fig. Figure 21 is a block diagram showing an overall view of a functional configuration of a control unit of the blood pressure measuring device of the second embodiment. Fig. Figure 22 is a flowchart showing an example of the overall process carried out by the blood pressure measuring device of the second embodiment. Fig. Figure 23 is a drawing showing examples of the images displayed by an output unit of the blood pressure measuring device of the second embodiment. Description of the embodiments

[0043] Specific embodiments of the present invention are described below with reference to the drawings. Unless otherwise specified in detail, it is not intended that the materials, shapes, relative arrangements, and similar features of the structural elements described in the following embodiments limit the technical scope of this invention. First embodiment

[0044] First, a first embodiment of the present invention is described with reference to Fig. Figures 1 to 19 describe. A blood pressure measuring device according to the present embodiment is a device for measuring the pressure pulse wave of a radial artery using tonometry. Here, tonometry refers to a method in which an artery is compressed from above the skin with suitable pressure to create a flattened section in the artery, where the internal and external pressures of the artery are equalized, and a pressure pulse wave is measured non-invasively by pressure sensors. Blood pressure monitor configuration

[0045] Fig. Figure 1 is a block diagram showing the overall configuration of a blood pressure monitor 1 according to the present embodiment. The blood pressure monitor 1 mainly comprises a measuring unit 10, a control unit 20, an input unit 30, and a storage unit 40.

[0046] Note that the blood pressure monitor 1 can be a stationary device, used in a state where the upper arm of the person being measured is placed on a fixation base during the measurement, or it can be a portable device, which is attached in such a way that it does not restrict the movement of the person being measured during the measurement. In the case where the blood pressure monitor 1 is a portable device, the movement of the person being measured is not restricted, but the blood pressure monitor 1 tends to deviate from a state suitable for blood pressure measurement.In view of this, with a device of the present embodiment which can maintain the degree of reliability of the measured blood pressure information, it is possible to prevent blood pressure information measured in an unsuitable condition from being treated as blood pressure information measured in a suitable condition, and therefore such a device is preferable.

[0047] The measuring unit 10 measures the pressure pulse wave of a measuring person by using a sensor unit 11. Fig. Figure 2 is a drawing showing a state in which the measuring unit 10 is attached to the left wrist of the person being measured by a strap, which is not shown, and Fig. Figure 3 is a cross-sectional drawing which schematically shows the structure of the measuring unit 10 and its state during the measurement. As in Fig. 2 and Fig. As shown in Figure 3, the measuring unit 10 includes a sensor unit 11 and a pressure mechanism 12 to press the sensor unit 11 against the wrist, and the measuring unit 10 is arranged to come into contact with the body surface at the location of a radial artery TD, which is the blood pressure measurement target.

[0048] Fig. Figure 4 is a drawing showing a side surface of a sensor unit 11 that comes into contact with the body surface. As in Fig. As shown in Figure 4, the sensor unit 11 has a first sensor field 111, which is formed by many (e.g. 46) pressure sensors 110, which are arranged side by side in a direction B, which intersects a direction A, which is the direction of extension of the radial artery TD, which is placed at the mounting location when the measuring unit 10 is attached, and a second sensor field 112, which is arranged parallel to the first sensor field 111.

[0049] The pressure sensors 110, which represent the first and second sensor fields 111 and 112, are arranged with spaces between them, in which a necessary and sufficient number of pressure sensors are arranged above the radial artery TD. Furthermore, the pressure sensors 110 in each of the sensor fields are arranged such that they form pairs with the pressure sensors 110 that represent the other sensor field. Here, a piezoelectric element that measures the pressure and converts it into an electrical signal, an element that applies the piezoresistance effect, or similar devices can preferably be used as the pressure sensors 110.

[0050] The pressure mechanism 12, for example, is constructed using an air bellows and a pump that adjusts the internal pressure of the air bellows. When the control unit 20 controls the pump to increase the internal pressure of the air bellows, the pressure sensors 110 are pressed against the body surface by the expansion of the air bellows. Note that the pressure mechanism 12 can be any mechanism capable of adjusting the force required to press the pressure sensors against the body surface and is not limited to a mechanism that uses an air bellows.

[0051] The control unit 20 performs various operations, such as controlling the units of the blood pressure monitor 1, recording and analyzing measured data, and inputting and outputting data. The control unit 20 includes a processor, a ROM (read-only memory), a RAM (access memory), and similar components. The functions of the control unit 20, described later, are implemented by the processor, which reads the programs stored in the ROM or memory unit 40 and executes them. The RAM functions as working memory when the control unit 20 performs various operations.

[0052] The input unit 30 provides a user interface. For example, it is possible to use the control buttons, switches, a touch panel, or similar.

[0053] The storage unit 40 is a storage medium that enables the loading and reading of data and stores programs executed by the control unit 20, measurement data received from the measuring unit 10, various types of data obtained by processing the measurement data, and similar information. Flash memory is used, for example, as the storage unit 40. The storage unit 40 can be a portable storage device, such as a memory card, or it can be built into the blood pressure monitor 1. Functions of the control unit

[0054] Fig. Figure 5 is a block diagram showing an overview of the functional configuration of control unit 20. As shown in Fig. As shown in Figure 5, the control unit 20 has as basic functions a feature size extraction unit 21, a tonogram generation unit 22, a conclusion unit 23 of an arrangement state, a reliability calculation unit 24 and a blood pressure index specification unit 25. In the present embodiment, the functions of these units are implemented by the control unit 20, which executes the necessary programs.

[0055] The feature quantity extraction unit 21 is a function for extracting feature quantities from an arterial pressure waveform measured by the blood pressure measurement unit for each heartbeat. The feature quantities extracted in the present embodiment are, for example, the maximum and minimum pressure values ​​of each heartbeat and the difference between the maximum and minimum pressure values.

[0056] The tonogram generation unit 22 is a function for generating a tonogram. Here, the term "tonogram" refers to the distribution profile of the feature variable values ​​for the plurality of pressure sensors. In the present embodiment, a tonogram is created for each of the sensor fields, based on the difference between the maximum pressure value and the minimum pressure value of each heartbeat (hereinafter referred to as the "AC component") and the minimum pressure value (hereinafter referred to as the "DC component"), which are extracted by the feature variable extraction unit 21.

[0057] The inference unit 23 of the arrangement state is a function for inferring the arrangement state of the sensor unit 11 relative to the radial artery TD, based on the shape of a tonogram. In the present embodiment, a final inference is made within 64 patterns of the arrangement states.

[0058] The reliability calculation unit 24 is a function for calculating the reliability of the blood pressure information measured by the measuring unit 10, based on the inferred arrangement state of the sensor unit 11.

[0059] The blood pressure index specification unit 25 is a function for specifying blood pressure indices, which are intended to be final measured values, based on blood pressure information measured by the multiple pressure sensors 110. The blood pressure indices specified in the present embodiment are the systolic blood pressure (SBP), the diastolic blood pressure (DBP), and the pulse rate (PR). Functions of the blood pressure monitor

[0060] The following describes functions of the blood pressure monitor 1 in the present embodiment. Fig. Figure 6 is a flowchart showing an example of the overall sequence of the process performed by the blood pressure monitor 1 of the present invention. As shown in Fig. As shown in Figure 6, the blood pressure device 1 measures the blood pressure information for each heartbeat (step S2), extracts feature sizes from the measured information and generates a tonogram (step S3), infers the arrangement state of the sensor unit 11 relative to the radial artery TD based on the tonogram (step S4), calculates a reliability based on the determined or inferred arrangement state (step S5) and records the reliability and the measured blood pressure information in the storage unit 40 (step S6). Measuring blood pressure information

[0061] When the measuring unit 10 is attached to the wrist and the blood pressure monitor 1 is started, the control unit 20 controls the pressure mechanism 12 of the measuring unit 10 and maintains the pressure force applied to the sensor unit 11 in a suitable state. The control unit 20 successively receives the blood pressure information measured by the pressure sensors 110.

[0062] Fig. Figure 7 shows an arterial pressure waveform (tonometry sensor pressure) measured by a pressure sensor 110. The horizontal axis represents time, and the vertical axis represents blood pressure. The sampling frequency is 125 Hz in the present embodiment but can be adjusted as desired, provided it is possible to reproduce the waveform characteristics for a heartbeat. Feature size extraction and tonogram

[0063] The feature size extraction unit 21 extracts an AC (direct current) component and a DC (alternating current) component for the arterial pressure waveforms measured by the pressure sensors 110. The tonogram creation unit 22 also generates a graph, which is essentially a tonogram, plotting the positions on a sensor field on the horizontal axis where the pressure sensors 110, representing these positions, are located, and printing the AC and DC components for each pressure sensor 110 on the vertical axis in the same heartbeat. Fig. Figure 8 is a diagram showing an example of the tonogram. The pressure sensors 110 are assigned channel numbers according to their positions.

[0064] In the present embodiment, the pressure sensor 110 that has the highest AC component value (peak value) in each sensor field is considered the peak channel, and the pressure sensor 110 that has the lowest AC component value (lowest value) is considered the lowest channel. The tonogram for the first sensor field 111 is also called the first tonogram, and the peak value and the lowest value of the first tonogram are each called the first peak value and the first lowest value. Furthermore, the tonogram for the second sensor fluid 112 is called the second tonogram, and the peak value and the lowest value of the second tonogram are each called the second peak value and the second lowest value.

[0065] The blood pressure index specification unit 25 selects as the active channel which has the larger AC component value of the peak channel of the first sensor field 111 and the peak channel of the second sensor field 112, and specifies various blood pressure indices from the blood pressure information which is measured on the active channel. Relationship between tonogram and sensor unit arrangement state

[0066] Fig. Figure 9 is a drawing which shows a state in which the sensor unit 11 is suitably arranged relative to the radial artery TD, and the shapes of the tonograms in this arrangement state, and Fig. 10, Fig. 11, Fig. 12, Fig. 13, Fig. 14, Fig. 15 and Fig. Figure 16 shows seven patterns in which the sensor unit 11 is not suitably arranged relative to the radial artery TD, and the shapes of the tonograms in these arrangement states. Note that in the present specification, a suitable arrangement state is assumed to be one in which, out of the two sensor fields, the first sensor field 111 is arranged at a location most suitable for pulse pressure wave measurement.

[0067] As in Fig. As shown in Figure 9, the state in which the sensor unit 11 is suitably arranged relative to the radial artery TD is defined as the state in which the AC component of the first tonogram is shaped as a peak with the apex channel located at the approximate center, the AC component of the second tonogram is shaped as a slightly flatter peak than in the tonogram of the first sensor field 111, and the DC components of the first sensor field 111 and the second sensor field 112 have an almost flat shape.

[0068] Accordingly, as in Fig. As shown in Figure 10, in the case where both the AC components and the DC components in the first and second tonograms have a flat shape with a low level (the peak value is low and the difference between the peak value and the lowest value is small), it can be concluded that the arrangement state is a state in which the force for pressing the sensor unit 11 against the radial artery TD is too weak, i.e., an insufficient pressure state.

[0069] Also, as in Fig. As shown in Figure 11, in the case where both the AC component and the DC component in the first and second tonograms have a flat shape with a high level (the peak value is high and the difference between the peak value and the lowest value is small), it can be concluded that the arrangement state is a state in which the force for pressing the sensor unit 11 against the radial artery TD is excessive, i.e., an excessive pressure state.

[0070] Also, as in Fig. As shown in Figure 12, in the case where in either the first tonogram or the second tonogram the AC component and the DC component both have a flat shape with a low level and in the other tonogram the AC component and the DC component both have a flat shape with a high level, it can be concluded that the arrangement state is a state in which the sensor unit 11 is inclined in a direction parallel to the direction of extension of the radial artery TD (this inclination direction is hereafter referred to as the “arterial direction”), i.e. a tilt state of the arterial direction.

[0071] Also, as in Fig. As shown in Figure 13, in the case where the DC component of the first tonogram is shaped as a line which is inclined in a direction instead of being flat, it can be said that the arrangement state is a state in which the sensor unit 11 is inclined in a direction perpendicular to the extension direction of the radial artery TD (this inclination direction is hereafter referred to as the "lateral direction"), i.e. a lateral direction inclination state.

[0072] Also, as in Fig. As shown in Figure 14, in the case where the position of the tip channel in the first tonogram is largely shifted to the left or right of the center, it can be said that the arrangement state is a state in which the sensor unit 11 is shifted in the width direction, i.e. a width direction displacement state.

[0073] Also, as in Fig. As shown in Figure 15, in the case where the difference between the heights of the peak values ​​in the first tonogram and the second tonogram is not very large (the difference between the output signal values ​​of the peak channels is small), it can be said that the arrangement state is a state in which the sensor unit 11 is shifted in the arterial direction, i.e. a displacement state of the arterial direction.

[0074] Also, as in Fig. As shown in Figure 16, in the case where the positions of the tip channels are largely shifted between the first tonogram and the second tonogram, it can be said that the arrangement state is a state in which the sensor unit 11 is shifted in the direction of rotation into the plane of contact with the body surface, i.e. a displacement state of a rotation. Determining or inferring the state of the arrangement and calculating the reliability

[0075] The determination unit 23 of the arrangement state infers the arrangement state of the sensor unit 11 relative to the radial artery TD based on the feature sizes and / or the shapes of the tonograms, and the calculation unit 24 of the reliability calculates a reliability corresponding to the arrangement state. Fig. Figure 17 is a flowchart which shows an example of the process which is carried out when a determination unit 23 of the arrangement state infers the arrangement state of the sensor unit 11. Fig. 18 and Fig. 19 are parts of a flowchart which provides an example of the process in the step "Determine pressure state and arterial inclination" in Fig. 17 shows, and a single process is described in Fig. 18 and Fig. 19 shown. The following describes a procedure by which the inference unit of the arrangement state determines an arrangement state with reference to Fig. 17, Fig. 18 and Fig. 19 concludes.

[0076] The determination unit 23 of the arrangement state and the calculation unit 24 of the reliability are each set with “arrangement state identifier = none (suitable state)” and “reliability = 100” as initial values ​​(step S100).

[0077] The arrangement state determination unit 23 first performs a determination regarding "pressure magnitude and inclination of the arterial direction" (step S101). As in Fig. 18 and Fig. As shown in Figure 19, the inference unit 23 of the arrangement state infers the extent of the pressure of the first sensor field 111, then infers the extent of the pressure of the second sensor field 112, and then infers the “pressure state and inclination of the arterial direction” of the sensor unit 11 based on a combination of the extents of the pressure of the first sensor field 111 and the second sensor field 112.

[0078] Specifically, for sensor field 111, it is first determined whether the difference between the first peak value and the first lowest value exceeds a predefined output signal value difference threshold (step S111). If the difference between the first peak value and the first lowest value exceeds the predefined output signal value difference threshold, it is concluded that the degree of pressure applied to the first sensor field 111 is appropriate (step S112).

[0079] If the difference between the first peak value and the first lowest value does not exceed the predefined output signal difference threshold in step S111, it is then determined whether the first peak value exceeds a predefined excessive pressure level threshold (S113). Here, if the first peak value exceeds the excessive pressure level threshold, it is concluded that the pressure level of the first sensor field 111 is an excessive pressure condition (step S114).

[0080] If the first peak value does not exceed the excessive pressure level threshold in step 113, it is then determined whether the first lowest value is below a predefined insufficient pressure level threshold (S115). Here, if the first lowest value is below the predefined insufficient pressure level threshold, it is concluded that the pressure level of the first sensor field 111 is an insufficient pressure condition (S116), and if it is not below the predefined insufficient pressure level threshold, it is concluded that the pressure level of the first sensor field 111 is adequate.

[0081] Next, the pressure level for the second sensor field 112 is also deduced similarly to the case of the first sensor field 111 (steps S117 to S122).

[0082] Subsequently, it is determined whether the first sensor field 111 and the second sensor field 112 are both under excessive pressure (step S123). Here, if the excessive pressure state is inferred in both cases, it is concluded that the sensor unit 11 is in the “excessive pressure state” against the radial artery TD, and “excessive pressure state” is added to the arrangement state identifier (S124).

[0083] If a negative determination is made in step S123 regarding whether or not both the first sensor field 111 and the second sensor field 112 are excessively pressed, it is determined whether or not both the first sensor field 111 and the second sensor field 112 are insufficiently pressed (step S125). Here, if it is determined that both the first sensor field 111 and the second sensor field 112 are in the insufficient pressure state, it is inferred that the sensor unit 11 is in the "insufficient pressure state" against the radial artery TD, and "insufficient pressure state" is added to the arrangement state identifier (step S126).

[0084] If a negative determination is made in step S125 regarding whether or not both of the first sensor field 111 and the second sensor field 112 are in the insufficient pressure state, it is determined whether one of the first sensor field 111 and the second sensor field 112 is in the excessive pressure state and the other is in the insufficient pressure state (S127). Here, if it is determined that either one of the first sensor field 111 and the second sensor field 112 is in the excessive pressure state and the other is in the insufficient pressure state, it is inferred that the sensor unit 11 is in the "arterial direction tilt state" relative to the radial artery TD, and the "arterial direction tilt state" is added to the arrangement state identifier (step S128).

[0085] If a negative determination is made in step S127 as to whether one of the first sensor field 111 and the second sensor field 112 is in the excessive pressure state or not, and the other is in the insufficient pressure state or not, it is concluded that the sensor unit 11 is in the “suitable arrangement state” relative to the radial artery TD (step S129).

[0086] Even if the arrangement state inferred by the arrangement state inference unit 23 is the “excessive pressure state”, the “insufficient pressure state” or the “arterial direction tilt state”, the reliability calculation unit 24 subtracts 30 from the reliability value.

[0087] As in Fig. As shown in Figure 17, the design unit 23 of the arrangement state then determines whether the sensor unit 11 is inclined in the lateral direction or not (step S102). Specifically, a “DC component inclination” is obtained as the difference between the value of the DC component from the pressure sensor 110, which is located on the channel that is 10 higher than the peak channel in the first sensor field 111, and the value of the DC component from the pressure sensor 110, which is located on the channel that is 10 lower than the peak channel in the first sensor field 111.

[0088] If the DC component tilt value described above is greater than or equal to a predefined DC component tilt threshold, the arrangement state inference unit 23 concludes that the sensor unit 11 is in the "lateral tilt state" relative to the radial artery TD and adds "lateral tilt state" to the arrangement state identifier (step S103). The reliability calculation unit 24 also subtracts the value 70 / 4 from the reliability value.

[0089] Note that the DC component slope only needs to be obtained by using values ​​at two or more points in the tonogram; it is not necessarily limited to obtaining it by using the positions of the pressure sensors 110 at the channels described above, and it can be obtained by linear regression using the values ​​of all channels.

[0090] The arrangement state determination unit 23 subsequently determines whether the sensor unit 11 is displaced in the lateral direction or not (step S104). Specifically, if the number of channels of the peak channel in the first sensor field 111 is not within a permissible range for the peak channel position, it is inferred that the sensor unit 11 is in the "lateral displacement state" relative to the radial artery TD, and the "lateral displacement state" is added to the arrangement state identifier (step S105). The reliability calculation unit 24 also subtracts the value 70 / 4 from the reliability value.

[0091] In this case, where the sensor fields are each constructed using, for example, 46 pressure sensors 110, the permissible range for the peak channel position can be a numerical value range of 20 to 26, with 20 being the lower limit threshold of the peak channel and 26 being the upper threshold of the peak channel.

[0092] Note that the procedure for determining whether the sensor unit is displaced in the lateral direction or not is not limited to the above description, and it is also possible to infer that the arrangement state is the lateral displacement state if, for example, the AC component of a tonogram has many peaks, i.e., if there are two or more local maximum values ​​in the AC component.

[0093] The arrangement state determination unit 23 subsequently determines whether the sensor unit 11 is displaced in the arterial direction or not (step S106). Specifically, if the difference between the peak value of the first sensor field 111 and the peak value of the second sensor field 112 is below the previously defined peak difference threshold, it is concluded that the sensor unit 11 is in the "arterial direction displacement state" relative to the radial artery TF, and the "arterial direction displacement state" is added to the arrangement state identifier (step S107). The reliability calculation unit 24 subtracts the value 70 / 4 from the reliability value.

[0094] The arrangement state determination unit 23 subsequently determines whether the sensor unit 11 is displaced in the direction of rotation or not (step S108). Specifically, if the difference between the peak channel count of the first sensor field 111 and the peak channel count of the second sensor field 112 exceeds a predefined peak channel difference threshold, it is concluded that the sensor unit 11 is in the "rotational displacement state" relative to the radial artery TD, and the "rotational displacement state" is added to the arrangement state identifier (step S109). The reliability calculation unit 24 also subtracts the value 70 / 4 from the reliability value.

[0095] As described above, it is finally concluded that the arrangement state of the sensor unit 11 relative to the radial artery TD is one of 64 patterns, the reliability of the measured value is calculated according to the inferred arrangement state, and the calculated reliability is recorded in the storage unit 40 together with the measured blood pressure information and the specified blood pressure indices. Effects of the blood pressure measuring device of the present invention

[0096] According to the configuration described above, the blood pressure monitor 1 of the present invention can efficiently infer the arrangement state of the sensor unit 11 from the perspective of the pressure magnitude, the inclination of the arterial direction, the inclination of the lateral direction, the displacement of the arterial direction, the displacement of the lateral direction, and the displacement of the rotation. Furthermore, based on the arrangement state of the sensor unit 11, which is inferred in this way, it is possible to obtain the reliability of the blood pressure information measured by the sensor unit 11 on a scale of 100 points. For this reason, it can be prevented that the blood pressure information obtained when the sensor unit is in an unsuitable arrangement state (i.e.,where a measured value has low reliability), is treated similarly to blood pressure information, which is obtained when the sensor unit 11 is in a suitable arrangement state (i.e. where a measured value has high reliability). Variations

[0097] Note that although the reliability value calculation is performed in five steps for inference to the arrangement state in the present embodiment, it is not necessary to apply this procedure, and the reliability can be calculated based on the final inferred or derived arrangement state.

[0098] Although the “pressure magnitude and inclination of arterial direction” state is set to a value which has a greater influence on reliability than the other unsuitable arrangement states (30 for the previous one and 70 / 4 for the latter) in the present embodiment, it is not necessarily required that the values ​​be set in this way.

[0099] Furthermore, although reliability is calculated on a scale of 100 points in the present embodiment, it is not necessarily required to have such a range of continuous values, and reliability can be expressed by evaluation classes such as "reliable", "conditionally reliable", "not very reliable", "hardly reliable" and "not reliable at all".

[0100] Although it is ultimately derived that the arrangement state is one of 64 patterns in the present embodiment, there is no limit to this, and the arrangement state can be derived from a larger number of patterns. For example, although only "yes" and "no" are derived for translation and tilting in the present embodiment, it is possible to add the element of "in which direction" when the translation or tilting occurs, so that the final arrangement state is derived from approximately 729 patterns of arrangement states. Furthermore, it is possible to add the element of "to what extent" and derive the arrangement state in greater detail.

[0101] The inference can also be made conversely regarding the arrangement state, using fewer determining elements. For example, the final arrangement state can be derived based on only "the pressure magnitude," "the presence / absence of the lateral displacement," and "the presence / absence of the lateral inclination." In such a case, the arrangement state can be derived simply by using a sensor array.

[0102] Furthermore, the information recorded on the storage unit 40 is not limited to the information described in the present invention, and it is possible to additionally record data indicating the tonograms generated by the tonogram creation unit 22 and information indicating the arrangement state derived by the arrangement state inference unit 23. Second embodiment

[0103] A second embodiment of the present invention is described below with reference to the Fig. Sections 20 to 23 describe the hardware configuration of the present embodiment. Note that the hardware configuration of the present embodiment is essentially the same as that of the first embodiment, except that it has an output signal unit 50. Therefore, the same sub-areas are given the same reference numerals as in the first embodiment and are not described in detail. The procedure performed by the blood pressure monitor and the functions of the control unit 20 are also largely the same as in the first embodiment, and therefore detailed descriptions for such sub-areas are not given. Blood pressure monitor configuration

[0104] Fig. Figure 20 is a block diagram showing the overall configuration of a blood pressure monitor 2 of the present invention. The blood pressure monitor 2 essentially comprises the measuring unit 10, the control unit 20, the input unit 30, the storage unit 40, and an output unit 50. As mentioned above, with the exception of the output unit 50, the configurations and functions are similar to those in the first embodiment.

[0105] The output unit 50 provides the user with interfaces for outputting information. In the present embodiment, it is assumed that the output unit 50 has a liquid crystal display and a loudspeaker; however, the present invention is not necessarily limited to this. For example, it is also possible to use a display device other than a liquid crystal display, an audio output device other than a loudspeaker, a communication device that performs data communication with another device, and the like. The data communication performed in the communication device can be wired or wireless. A combination of the above is also possible. Functions of the control unit

[0106] Fig. Figure 21 is a block diagram showing an overview of the functional configuration of the control unit 20. As shown in Fig. As shown in Figure 21, the control unit 20 has as basic functions the extraction unit 21 for feature size, the tonogram creation unit 22, the inference unit 23 of the arrangement state, the reliability calculation unit 24, the blood pressure index specification unit 25, and a processing unit 26 of the output arrangement state. In the present embodiment, the functions of these units are implemented by the control unit 20, which executes the necessary programs. The configurations, unlike the processing unit 26 of the output arrangement state, are similar to those in the first embodiment.

[0107] The processing unit 26 of the output arrangement state is a function for carrying out the processing, according to which the output unit 50 described later carries out the output, which corresponds to the derived arrangement state of the sensor unit 11. Functions of the blood pressure monitor

[0108] Fig. Figure 22 is a flowchart showing an example of the overall sequence of operations performed by the blood pressure monitor 2 of the present embodiment. As shown in Fig. As shown in Figure 22, the blood pressure monitor 2 measures the blood pressure information for each heartbeat (step S22), extracts feature parameters from the measured information and generates a tonogram (step S23), determines or infers the arrangement state of the sensor unit 11 relative to the radial artery TD based on the tonogram (step S24), and calculates a reliability based on the inferred arrangement state (step S25). The process up to this point is similar to that in the first embodiment.

[0109] The blood pressure monitor 2 further determines whether or not the inferred output arrangement state of the sensor unit 11 is “suitable” (step S26), and based on the determination that it is not “suitable”, it outputs a warning signal from the output unit 50 (step S27).

[0110] The blood pressure monitor then displays the blood pressure indices on a display unit, which are specified by the blood pressure index specification unit 25, a representation of the estimated output arrangement state of the sensor unit 11, the calculated reliability and a comment regarding the inferred arrangement state (step S28).

[0111] The blood pressure information measurement, the extraction of the feature size, the determination or inference of the arrangement state and the reliability calculation are similar to those in the first embodiment and are therefore not described, and the following describes the workflow which the processing unit 26 performs in the output of the output arrangement state based on the inferred arrangement state.

[0112] Processing unit 26 of the output of the arrangement state first determines whether the inferred arrangement state is "suitable," and if it is not "suitable," it processes the information by emitting a warning tone, based on a warning signal, from a loudspeaker. Note that the case in which the output arrangement state is not suitable refers to the case in which the reliability of the measured blood pressure information is less than or equal to a predefined value; therefore, determining whether or not to emit the warning signal can be based on whether or not the reliability value exceeds the predefined value.

[0113] Here, the tone can be a type of warning tone, or it can be different types of warning tones corresponding to different order states. A warning can also be given according to the order state by using a speech-based voice message. In this case, the voice data can be obtained by selecting the appropriate voice data from a voice database in storage unit 40.

[0114] The processing unit 26 of the output of the arrangement state also performs the processing for display on the display unit of a "representation image of the arrangement state", which corresponds to the inferred arrangement state. Here, the representation image of the arrangement state can be obtained by selecting corresponding representation image data of the arrangement state from a representation image database of the arrangement state in the storage unit 40.

[0115] Furthermore, the processing unit 26 of the output of the arrangement state performs the processing for displaying, on a display unit, a "comment of the arrangement state" which corresponds to the inferred arrangement state. The comment of the arrangement state can also be displayed in the case where the arrangement state is not "suitable," together with a "correction instruction comment" which indicates how the arrangement state must be corrected to become suitable. Here, the arrangement state comment and the correction instruction comment can be obtained by selecting data from a database in storage unit 40. In this case, it is possible to prepare comment data in which a correction comment is contained within the arrangement state comment, and an arrangement state comment and a correction comment can be stored separately in the database. Displaying the information on a display device

[0116] Together with the information obtained by processing the processing unit 26 of the output of the arrangement state as described above, the control unit 20 displays on a liquid crystal display: the first tonogram, which is generated by the tonogram generation unit 22, the reliability, which is calculated by the reliability calculation unit 24, and the blood pressure indices, which are specified by the blood pressure index specification unit 25. Fig. 23A and Fig. Figure 23B shows examples of such a display screen. Fig. Figure 23A shows an example of the case in which the sensor unit 11 is in a suitable arrangement state relative to the radial artery TD, and Fig. Figure 23B shows an example of the case in which the sensor unit 11 is displaced and tilted in the lateral direction. Effects of the blood pressure monitor of the present embodiment

[0117] In accordance with the configuration described above, the user of the blood pressure monitor 2 of the present embodiment can determine the measured blood pressure indices (SBP, DBP, and PR) and the reliability of these indices in a more timely manner by displaying the information on the liquid crystal display. Furthermore, the display of the illustrative image and text information allows the user to determine the position of the sensor unit 11 relative to the radial artery TD, which is the measurement site, in a more timely manner.

[0118] Even if the reliability of the blood pressure information, which includes the blood pressure indices, is less than or equal to the previously defined reference value, the user of the blood pressure monitor 2 of the present embodiment can immediately ascertain this fact through audio and / or a display screen. Furthermore, an unsuitable configuration that causes a reduction in reliability can be identified more quickly through an illustrative image and textual information, and a method for bringing the sensor unit 11 into a suitable configuration can be determined by the display of the textual information. Therefore, the user can independently correct the configuration of the sensor unit 11 to a state suitable for blood pressure measurement. Variations

[0119] Instead of displaying various types of information only on the screen, this information can be recorded in memory unit 40 if required. Furthermore, there is no limitation to just the displayed information; a configuration is possible in which all measured blood pressure information, secondary tonogram data, and similar data are also recorded.

[0120] Even though the information is displayed on a liquid crystal display integrated with the blood pressure monitor in the present embodiment, the information can be transmitted via a communication device and a monitor separate from the blood pressure monitor, or displayed via a projector or a mobile information terminal, such as a smartphone.

[0121] Although a tone is emitted as the warning signal in the present embodiment, there is no limitation to this, and a warning can, for example, be issued by flashing a light. In such a case, this can be done via the screen of the liquid crystal display or by using an LED or similar device that is separate from the display. Reference symbol list 1.2 Blood pressure monitor 10 Unit of measurement 11 Sensor unit 12 Pressure mechanism 110 Pressure sensor 111 first sensor field 112 second sensor field 20 Control unit 21 Feature size extraction unit 22 Tonogram generation unit 23 Arrangement status determination unit 24 Reliability calculation unit 25 Blood Pressure Index Specification Unit 26 Arrangement state-Output-Processing unit 30 Input unit 40 storage units 50 output units TD Radial Artery

Claims

[1] Blood pressure measuring device (1) which measures blood pressure by tonometry, wherein the blood pressure measuring device (1) has: a measuring device (11) which includes a plurality of pressure sensors (110) and serves to measure the blood pressure information for each heartbeat at a measuring location; an arrangement state inference device (23) for extracting a feature quantity from an output signal waveform for each of the pressure sensors (110) for each heartbeat, and deriving or inferring an arrangement state of the measuring device (11) relative to an artery, which is the object being measured, based on a distribution profile of the values ​​of the feature quantity for the plurality of pressure sensors (110); and a reliability calculation device (24) for calculating the reliability of the blood pressure information measured by the measuring device (11) based on the determined or inferred arrangement state, wherein the arrangement state inference device (23) extracts from the output signal waveform of each of the pressure sensors (110) for each heartbeat a difference value between a maximum value and a minimum value in the output signal waveform and / or the minimum value as the feature size and estimates the arrangement state of the measuring device (11) based on a distribution profile of the difference value for the plurality of pressure sensors (110) and / or a distribution profile of the minimum value, wherein the measuring device (11) has at least one sensor array which is composed of a plurality of pressure sensors (110) arranged side by side in a direction which intersects the artery during the measurement, wherein the arrangement state includes a slope of a lateral direction which indicates the slope in a direction perpendicular to a direction of the extension of the artery relative to a reference state which is an orientation or alignment suitable for measurement, and the arrangement state inference device (23) determines or infers the slope of the lateral direction based on a slope in the distribution profile of the minimum value. [2] Blood pressure measuring device (1) according to claim 1, wherein the arrangement state includes a pressure magnitude which indicates a magnitude of force exerted by the sensor field on the artery, and the arrangement state inference device (23) determines or infers the pressure level based on a difference between a peak value and a lowest value in the distribution profile of the difference value and / or the peak value in the distribution profile of the difference value. [3] Blood pressure measuring device (1) according to claim 1 or 2, wherein the arrangement state includes a displacement of the lateral direction which indicates a displacement in a direction perpendicular to a direction of the extension of the artery relative to a reference state which is an orientation which is suitable for measurement, and the arrangement state inference device (23) determines or infers the displacement of the lateral direction based on a position of a peak in the distribution profile of the difference value. [4] Blood pressure measuring device (1) according to one of claims 1 to 3, wherein the measuring device (11) includes a first sensor field (111) and a second sensor field (112) which are arranged parallel to each other, The arrangement state includes an inclination of the arterial direction, which indicates an inclination in a direction parallel to a direction of the extent of the artery relative to a reference state, which is an orientation suitable for measurement, and the arrangement state inference device (23) determines or infers the inclination of the artery based on a difference between a peak value and a lowest value in the distribution profile of the difference value and the peak value in the distribution profile of the difference value for each of the first sensor field (111) and the second sensor field (112). [5] Blood pressure measuring device (1) according to one of claims 1 to 4, wherein the measuring device (11) includes a first sensor field (111) and a second sensor field (112) which are arranged parallel to each other, The arrangement state includes a shift in the arterial direction, which indicates the shift in a direction parallel to a direction of the artery's extent relative to a reference state, which is an orientation suitable for measurement, and the arrangement state inference device (23) determines or infers the displacement of the artery based on a difference between the peak values ​​in the distribution profiles of the difference values ​​of the first sensor field (111) and the second sensor field (112). [6] Blood pressure measuring device (1) according to any one of claims 1 to 5, wherein the measuring device (11) includes a first sensor field (111) and a second sensor field (112) which are arranged parallel to each other, The arrangement state includes a shift in rotation, which indicates the rotation of the sensor field in a plane of contact with the object being measured, relative to a reference state, and which is an orientation suitable for measurement. the arrangement state inference device (23) determines or infers the displacement of the rotation based on a difference between the positions of the peaks in the distribution profiles of the difference values ​​of the first sensor field (111) and the second sensor field (112). [7] Blood pressure measuring device (1) according to any one of claims 1 to 6, which further comprises an output means to output one or a combination of the blood pressure information, the configuration state and the reliability. [8] Blood pressure measuring device (1) according to claim 7, wherein the output means is one or a combination of: a visual display device for outputting one or a combination of blood pressure information, arrangement status and reliability, using text and / or an image, a tone or sound output device for outputting one or a combination of blood pressure information, arrangement status and reliability, using a tone or sound, and a communication device for outputting, to another device, one or a combination of blood pressure information, arrangement status and reliability, using wired or wireless communication. [9] Blood pressure measuring device (1) according to claim 7 or 8, which further comprises a warning device for outputting information to the output device, indicating an unsuitable configuration state, indicating a decrease in reliability, in a case where the reliability is less than or equal to a previously determined reference value. [10] Blood pressure measuring device (1) according to one of claims 7 to 9, which further comprises a correction instruction device for outputting to the output device a method of correcting an unsuitable arrangement state which causes a decrease in reliability for a suitable arrangement state, in a case where the reliability is less than or equal to a previously determined reference value. [11] Blood pressure measuring device (1) according to any one of claims 1 to 10, wherein the blood pressure measuring device is a portable device to be attached to a wrist. [12] Method for controlling a blood pressure measuring device (1) which measures blood pressure by tonometry, wherein the method comprises: a measurement step of measuring the blood pressure information for each heartbeat in a measurement object by means of a measuring device (11), wherein the measuring device (11) has at least one sensor field which is composed of a plurality of pressure sensors (110) which are arranged side by side in a direction which intersects the artery during the measurement; a step of extracting a feature size from an output signal waveform for each of the pressure sensors (110) for each heartbeat, wherein from the output signal waveform of each of the pressure sensors (110) for each heartbeat a difference value between a maximum value and a minimum value in the output signal waveform and / or the minimum value is extracted as the feature size; a step of inferring an arrangement state of the measuring device (11) relative to an artery, which is the object being measured, based on a distribution profile of the feature size values ​​for the plurality of pressure sensors (110), wherein the arrangement state of the measuring device (11) is estimated based on a distribution profile of the difference value for the plurality of pressure sensors (110) and / or a distribution profile of the minimum value, wherein the arrangement state includes a lateral inclination indicating the inclination in a direction perpendicular to a direction of extension of the artery relative to a reference state, which is an orientation suitable for measurement, wherein the lateral inclination is determined or inferred based on an inclination in the distribution profile of the minimum value; and a step of calculating the reliability of the blood pressure information measured by the measuring device (11) based on the determined or inferred arrangement state. [13] Program for initiating the steps of the method of controlling a blood pressure measuring device (1), according to claim 12, which is to be carried out by the blood pressure measuring device (1).

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