JP2017029602A - Electronic sphygmomanometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic sphygmomanometer capable of determining whether or not a measurement result includes an error caused by body motion.SOLUTION: An electronic sphygmomanometer 1 for measuring blood pressure of a region to be measured comprises: a cuff pressure control unit for varying pressure of a cuff 20 mounted on the region to be measured; a pressure detection unit for detecting a cuff pressure signal showing pressure of the cuff; a pulse wave detection unit for extracting a pulse wave signal that is superposed on the cuff pressure signal and shows a pulse wave of the region to be measured, to acquire a string of amplitude shown by the pulse wave signal; an envelope curve creation unit for creating an envelope curve by connecting heights of amplitude of the string of amplitude acquired by the pulse wave detection unit; an acceleration detection unit for detecting body motion of the region to be measured to generate an acceleration signal; a body motion section ratio calculation unit that, on the basis of a detection result from the acceleration detection unit, calculates a body motion section ratio showing a ratio of a body motion occurrence section to a section in which the envelope curve is substantially projected upward; and a body motion reporting unit that, on the basis of the body motion section ratio, creates information showing at least three stages of body motion degree and reports the information.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an electronic sphygmomanometer, and more particularly to an electronic sphygmomanometer that measures a maximum blood pressure value and a minimum blood pressure value by an oscillometric method based on an arterial pulse wave component for each pulse superimposed on a cuff pressure.

  When body movement, which is the movement of the measurement site such as the upper arm of the subject, occurs during blood pressure measurement, the arm muscles expand and contract, and the internal volume of the cuff attached to the measurement site changes, resulting in the pressure in the cuff. Apply sudden pressure reduction or pressurization to (cuff pressure). When such a sudden cuff pressure change occurs, the pulse wave cannot be detected accurately, and the blood pressure measurement accuracy is adversely affected.

  As a conventional electronic blood pressure monitor, for example, as shown in Patent Document 1 (Japanese Patent Application Laid-Open No. 2011-200575), an error is displayed when blood movement is detected and measurement cannot be performed, and blood pressure measurement is stopped. A total has been proposed.

JP 2011-200575 A

  However, the electronic sphygmomanometer has a problem that the measurement result is displayed if the body motion is such that no error is detected, and it cannot be determined whether or not the measurement result includes an error due to the body motion.

  Accordingly, an object of the present invention is to provide an electronic sphygmomanometer that can notify the degree of body movement in multiple stages when body movement occurs during measurement.

In order to solve the above problems, an electronic sphygmomanometer according to the present invention provides:
An electronic sphygmomanometer that measures the blood pressure of a measurement site,
A cuff pressure control unit that changes the pressure of the cuff attached to the measurement site;
A pressure detector for detecting a cuff pressure signal representing the pressure of the cuff;
A pulse wave detection unit that extracts a pulse wave signal representing the pulse wave of the measurement site superimposed on the cuff pressure signal, and obtains an amplitude sequence indicated by the pulse wave signal;
For the amplitude column acquired by the pulse wave detection unit, an envelope creation unit that creates an envelope that connects the amplitudes; and
An acceleration detection unit that detects body movement of the measurement site and generates an acceleration signal;
Based on the detection result of the acceleration detection unit, a body motion section ratio calculation unit that calculates a body motion section ratio indicating a ratio of a body motion generation section to a section in which the envelope substantially forms a mountain;
A body motion notification unit that generates and reports information indicating the degree of body motion in at least three stages based on the body motion section ratio;
It is provided with.

  Here, the envelope is typically represented on a graph with the cuff pressure as the horizontal axis and the pulse wave amplitude as the vertical axis.

  In the electronic sphygmomanometer according to the present invention, the cuff pressure control unit changes the pressure of the cuff attached to the measurement site during measurement. In the pressure reducing process or pressurizing process of the cuff pressure, the pressure detection unit detects a cuff pressure signal representing the cuff pressure. The pulse wave detection unit extracts a pulse wave signal representing the pulse wave of the measurement site superimposed on the cuff pressure signal, and acquires an amplitude column indicated by the pulse wave signal. The envelope creation unit creates an envelope connecting the amplitudes of the amplitude columns acquired by the pulse wave detection unit. The acceleration detection unit detects the body movement of the measurement site and generates an acceleration signal. The body motion section ratio calculation unit calculates a body motion section ratio indicating the ratio of the body motion generation section to the section where the envelope substantially forms a mountain, based on the detection result of the acceleration detection unit. The body motion notifying unit generates and reports information indicating the degree of body motion in at least three stages based on the body motion section ratio.

  Thus, in the electronic sphygmomanometer according to the present invention, when there is a body movement during the measurement, the degree of the body movement can be notified in multiple stages. Furthermore, the measurement can be stopped and the re-measurement can be promoted only when the body movement that greatly affects the measurement result is detected.

In one embodiment of the electronic blood pressure monitor,
The body movement notifying unit generates and reports information indicating the degree of body movement in three stages using the first and second threshold levels,
The body motion notification unit displays a body motion mark indicating that there is body motion during measurement when the body motion section ratio is greater than the first threshold level and less than or equal to the second threshold level. When the body motion section ratio exceeds the second threshold level, a body motion error indicating that measurement is impossible is displayed.

  In the electronic sphygmomanometer according to the embodiment, the subject can specifically know the degree of body movement. Even if the body movement error is not displayed and the blood pressure measurement value is displayed, the subject determines that the measurement result includes an error due to body movement by referring to the display of the body movement mark after the measurement process. can do.

In one embodiment of the electronic blood pressure monitor,
When receiving the acceleration signal from the acceleration detection unit, further comprising a body movement occurrence location determination unit that determines whether the maximum peak in the envelope is included in the body movement generation section,
The body motion notifying unit sets the first and second threshold levels according to the determination result by the body motion occurrence location determining unit.

  In the electronic sphygmomanometer of this embodiment, the threshold level can be changed and set according to the position of the maximum peak in the envelope. For example, as compared with the first and second threshold levels when the maximum peak in the envelope is included in the body motion generation section, the first in the case where the maximum peak in the envelope is not included in the body motion generation section. The second threshold level is set large. As a result, notification according to the actual measurement accuracy becomes possible.

なる関係式が成立するときに上記包絡線における最大ピークが上記体動発生区間内に含まれると判断することを特徴とする。 In one embodiment of the electronic blood pressure monitor,
The body movement occurrence location determination unit generates intersections using a total of 4 points on each of the left and right sides outside the body movement generation section in the envelope,
When P is the pulse wave amplitude of the intersection, Q is the maximum pulse wave amplitude of the envelope, and k is an arbitrary real number,

It is determined that the maximum peak in the envelope is included in the body motion generation section when the following relational expression is satisfied.

  As is apparent from the above, according to the electronic sphygmomanometer of the present invention, when there is a body movement during the measurement, the degree of the body movement can be notified in multiple stages.

It is a perspective view which shows the external appearance of the electronic blood pressure meter 1 which concerns on the 1st Embodiment of this invention. It is a block diagram which shows roughly the internal structure of the electronic blood pressure meter 1 of FIG. It is a figure which illustrates the element comprised by CPU100 (software) of the electronic sphygmomanometer 1 in order to calculate a blood pressure value. It is a figure explaining the process at the time of calculating a blood-pressure value by the one part element in FIG. (A) is a figure which illustrates the cuff pressure signal detected via the pressure sensor of the said electronic sphygmomanometer, (B) illustrates the signal (HPF output) taken out from the said cuff pressure signal through the high-pass filter. FIG. It is a figure which expands the signal of Drawing 5 (B) about a decompression process, and illustrates it as a pulse wave signal showing a pulse wave of a measured part. It is a figure which shows the amplitude line which the pulse wave signal of FIG. 6 shows, and the envelope created about the amplitude line. It is a figure which shows the method of calculating a systolic blood pressure and a systolic blood pressure using the envelope of FIG. It is a flowchart which shows the blood-pressure measurement process which the electronic sphygmomanometer 1 of FIG. 1 performs. 10 is a flowchart illustrating in detail the body motion notification process in step S105 of FIG. 9. 1 is a time axis waveform diagram showing changes in signal levels of acceleration signals detected in the X axis direction, Y axis direction, and Z axis direction detected by the acceleration sensor 23 in FIG. 1 with respect to the measurement time, and blood pressure measurement in FIG. 1 with respect to the measurement time. It is a time-axis waveform diagram which shows the change of the cuff pressure of the cuff 20 for use. It is a figure which illustrates an envelope in case a body movement is detected. It is a figure which shows the blood pressure measurement error when there is no body movement. It is a figure which shows the blood pressure measurement error when there is a body movement. It is a graph for demonstrating the determination method of whether the amplitude maximum value of a pulse wave signal is included in the body movement generation | occurrence | production area in FIG.10 S202. It is a graph for demonstrating the determination method of whether the amplitude maximum value of a pulse wave signal is included in the body movement generation | occurrence | production area in FIG.10 S202. It is a figure which shows the example of a display displayed on the indicator 50 in FIG.9 S109. It is a figure which shows the example of a display displayed on the indicator 50 in FIG.9 S109. It is a figure which shows the example of a display displayed on the indicator 50 in FIG.9 S109. It is a graph which shows the measurement error of the systolic blood pressure value measured by this invention, and the measurement error of the systolic blood pressure value measured by the conventional method, respectively. FIG. 16B is a graph showing the measurement error of the minimum blood pressure value measured by the present invention and the measurement error of the minimum blood pressure value measured by the conventional method.

  Hereinafter, embodiments according to the present invention will be described with reference to the drawings. In the following embodiments, the same constituent elements are denoted by the same reference numerals, and the description thereof is omitted.

First embodiment.

  FIG. 1 is a perspective view showing an external appearance of an electronic sphygmomanometer 1 according to the first embodiment of the present invention. The electronic sphygmomanometer 1 in FIG. 1 includes a cuff 20 to be worn on the subject's upper arm, a main body 10, a flexible tube 38 that connects the cuff 20 and the main body 10, and at least one axis of body movement (motion) of the subject. And an acceleration sensor 23 for detecting the acceleration of the motor. Here, the cuff 20 contains a fluid bag 22 for pressing the upper arm. The main body 10 is provided with a display 50 and an operation unit 52. In this example, the operation unit 52 includes a power switch 52A, a memory switch 52B, a forward switch 52C, and a return switch 52D.

  FIG. 2 is a block diagram schematically showing the internal configuration of the electronic sphygmomanometer 1 of FIG. The main body 10 includes a CPU (Central Processing Unit) 100, a memory 51, a power supply unit 53, a piezoresistive pressure sensor 31, and a fluid bag 22 in addition to the display unit 50 and the operation unit 52 described above. As a pump 32 for supplying air, a valve 33 for adjusting the pressure (cuff pressure) of the fluid bag 22, an oscillation circuit 310 for converting the output from the pressure sensor 31 into a frequency, and a pump for driving the pump 32 A drive circuit 320, a valve drive circuit 330 that drives the valve 33, and an A / D conversion circuit 340 are mounted. The pressure sensor 31, the pump 32, and the valve 33 are connected to the fluid bag 22 contained in the cuff 20 through an air pipe 39 provided inside the main body and the tube 38 communicating with the air pipe 39. . Thereby, air as fluid flows between the pressure sensor 31, the pump 32, the valve 33, and the fluid bag 22.

  As shown in FIG. 2, the acceleration sensor 23 functions as an acceleration detection unit, acquires information on the body movement of the subject such as sleeping, and outputs the acquired information to the CPU 100 as an acceleration signal. Here, the acceleration sensor 23 detects the acceleration of vibration caused by the body movement of the subject wearing the blood pressure measurement cuff 20 and converts the detected analog data, which is acceleration data, into a digital signal by the A / D conversion circuit 340. It converts and outputs to CPU100 as an acceleration signal. Specifically, the acceleration sensor 23 includes a three-dimensional acceleration sensor that detects accelerations in three orthogonal directions (X-axis direction, Y-axis direction, and Z-axis direction), and the X-axis direction, the Y-axis direction, and the Z-axis direction. Is a direction specific to the acceleration sensor 23 and changes according to a change in posture (direction and inclination) of the subject wearing the blood pressure measurement cuff 20. That is, the acceleration sensor 23 correctly matches the three directions to be detected (X-axis direction, Y-axis direction, and Z-axis direction) with the front-rear direction, the left-right direction, and the up-down direction of the blood pressure measurement cuff 20. Is arranged. Thereby, each acceleration component of the front-back direction, the left-right direction, and the up-down direction can be detected easily and accurately.

  The display 50 includes a display, an indicator, and the like, and displays predetermined information according to a control signal from the CPU 100.

  In operation unit 52, power switch 52A receives an instruction to turn on / off power supply unit 53 and an instruction to start blood pressure measurement. The memory switch 52 </ b> B accepts an instruction for causing the display device 50 to display the blood pressure measurement result data stored in the memory 51. The forward / return switches 52C and 52D accept a change instruction such as causing the display device 50 to display or advance the display content to the past. These switches 52 </ b> A, 52 </ b> B, 52 </ b> C, 52 </ b> D input an operation signal according to an instruction from the subject to the CPU 100.

  The memory 51 stores a program for controlling the electronic sphygmomanometer 1, setting data for setting various functions of the electronic sphygmomanometer 1, and blood pressure value measurement result data. Further, the memory 51 serves as a correlation storage unit for the driving voltage of the sample solenoid valve having substantially the same characteristics as the valve 33 to be controlled, and the flow start point voltage Vs at which the fluid starts flowing through the sample solenoid valve and the sample solenoid valve. The correlation between the fully opened limit voltage Vf is stored. The memory 51 is used as a work memory when the program is executed.

  The power supply unit 53 supplies power to each unit of the CPU 100, the pressure sensor 31, the pump 32, the valve 33, the display device 50, the memory 51, the oscillation circuit 310, the pump drive circuit 320, and the valve drive circuit 330.

  The CPU 100 operates as a cuff pressure control unit in accordance with a program for controlling the electronic sphygmomanometer 1 stored in the memory 51, and drives the pump 32 via the pump drive circuit 320 in accordance with an operation signal from the operation unit 52. At the same time, control is performed to drive the valve 33 via the valve drive circuit 330. The valve 33 is opened and closed in order to discharge or enclose the air in the fluid bag 22 to control the cuff pressure. Further, the CPU 100 calculates a blood pressure value based on a signal from the pressure sensor 31 and controls the display device 50 and the memory 51.

  The pump 32 supplies air to the fluid bag 22 in order to pressurize the pressure (cuff pressure) in the fluid bag 22 contained in the cuff 20. The valve 33 is opened and closed in order to discharge or enclose the air in the fluid bag 22 to control the cuff pressure. The pump drive circuit 320 drives the pump 32 based on a control signal given from the CPU 100. The valve drive circuit 330 opens and closes the valve 33 based on a control signal given from the CPU 100.

  The pressure sensor 31 and the oscillation circuit 310 function as a pressure detection unit that detects the pressure of the cuff. The pressure sensor 31 is, for example, a piezoresistive pressure sensor, and is connected to the fluid bag 22 contained in the pump 32, the valve 33, and the cuff 20 via the cuff air tube 39. In this example, the oscillation circuit 310 oscillates based on an electrical signal value based on a change in electrical resistance due to the piezoresistive effect from the pressure sensor 31 and generates a frequency signal having a frequency corresponding to the electrical signal value of the pressure sensor 31. Output to.

  When measuring blood pressure according to a general oscillometric method, the following operation is generally performed. That is, a cuff is wound around the measurement site (arm or the like) of the subject in advance, and at the time of measurement, the pump / valve is controlled so that the cuff pressure is higher than the maximum blood pressure and then gradually reduced. In the process of reducing the pressure, the cuff pressure is detected by a pressure sensor, and the fluctuation of the arterial volume generated in the artery at the measurement site is extracted as a pulse wave signal. The systolic blood pressure and the diastolic blood pressure are calculated based on changes in the amplitude of the pulse wave signal (mainly rising and falling) accompanying the change in cuff pressure at that time.

  FIG. 3 exemplifies elements configured by the CPU 100 (software) of the electronic sphygmomanometer 1 for calculating the blood pressure value. As shown in FIG. 3, the elements for calculating the blood pressure value are a pulse wave detection unit 61, an envelope creation unit 62, a threshold level setting unit 63, a maximum blood pressure calculation unit 64, and a minimum blood pressure calculation unit 65. A body motion occurrence location determination unit 66, a body motion section ratio calculation unit 67, and a body motion notification unit 68. FIG. 4 is a diagram for explaining processing when blood pressure values are calculated using some elements in FIG.

  A method for calculating a blood pressure value based on the cuff pressure signal Pc will be described below with reference to FIGS.

  i) First, the pulse wave detector 61 in FIG. 3 receives the cuff pressure signal Pc detected by the pressure sensor 31 and superimposes it on the cuff pressure signal Pc, as shown in FIG. A pulse wave signal SM representing the pulse wave of the part is taken out. That is, the pulse wave detection unit 61 detects, from the cuff pressure signal Pc, a pulse wave that is a pressure component superimposed on the cuff pressure signal Pc in synchronization with the heartbeat of the subject.

  FIG. 5A is a diagram illustrating the cuff pressure signal Pc detected through the pressure sensor of the electronic sphygmomanometer. FIG. 5B is a diagram illustrating a signal (HPF output) extracted from the cuff pressure signal Pc through a high-pass filter. FIG. 6 is a diagram illustrating the pulse wave signal representing the pulse wave of the measurement site by enlarging the signal of FIG. 5B in the decompression process.

  Here, as shown in FIG. 5 (A), the cuff pressure signal Pc corresponds to a pressure that rises (pressurization process) or decreases (decompression process) substantially linearly with time. It is a signal on which a fluctuation component accompanying an arterial volume change is superimposed. The pulse wave detector 61 extracts a fluctuation component (HPF output) as shown in FIG. 5B from the cuff pressure signal Pc through a high-pass filter (HPF), and outputs it as a pulse wave signal SM as shown in FIG. In this example, as shown in FIG. 6 (corresponding to the decompression process), the pulse wave signal SM starts to increase in about 12 seconds from the start of the measurement, reaches a maximum in about 16 seconds, and increases to about 16 seconds. Almost disappeared in 20 seconds.

Then, the pulse wave detection unit 61 acquires a column AL of the amplitude indicated by the pulse wave signal SM (hereinafter referred to as “pulse wave amplitude” as appropriate). In this example, as shown in FIG. 7, the pulse wave amplitude column AL has a cuff pressure as a horizontal axis and an amplitude (peak value) AM ₁ , AM ₂ ,..., AM _i ,. Represented as:

  ii) The envelope creation unit 62 in FIG. 3 creates an envelope EV connecting the amplitudes of the pulse wave amplitude column AL acquired by the pulse wave detection unit 61, as shown in FIG. To do.

  iii) The threshold level setting unit 63 in FIG. 3 obtains a maximum blood pressure threshold level Ths at a predetermined ratio with respect to the value of the maximum peak EVP in the envelope EV in order to obtain the maximum blood pressure BPsys and the minimum blood pressure BPdia. A minimum blood pressure threshold level Thd is calculated and set. In the present embodiment, the first threshold level Ths is 40% of the maximum peak EVP value, and the second threshold level Thd is 50% of the maximum peak EVP value.

  iv) The body motion section ratio calculating unit 67 in FIG. 3 shows the body motion section ratio indicating the ratio of the body motion generating section to the section where the envelope EV substantially forms a mountain, based on the detection result of the acceleration detection section. Is calculated.

  v) The body motion notifying unit 68 in FIG. 3 generates and reports information indicating the degree of body motion in at least three stages based on the body motion section ratio. The body motion notification unit 68 generates and notifies information indicating the degree of body motion in three stages using the first and second threshold levels. Here, when the body motion section ratio exceeds the second threshold level, the body motion notification unit 68 displays a “body motion error” indicating that measurement is impossible. In addition, the body motion notification unit 68 displays a “body motion mark” indicating that there is body motion during measurement when the body motion section ratio is greater than the first threshold level and less than or equal to the second threshold level. indicate.

  Specifically, when it is determined that there is a body movement, the body movement notification unit 68 displays a “body movement mark” on the display device 50 (see FIG. 15B described later). Furthermore, if the body motion notifying unit 68 determines that the body motion has a great influence on the measurement result based on the body motion section ratio, the “body motion error” indicating that blood pressure measurement is impossible. Is displayed on the display 50 (see FIG. 15C described later), and the blood pressure measurement is stopped. Except when the “body motion error” is displayed, the blood pressure value is calculated in step S107 as described later, and the calculated blood pressure value is displayed on the display 50. In this case, the blood pressure measurement process is not stopped, and the blood pressure value is measured based on the generated envelope EV. Does the subject measure again with reference to the “body movement mark” displayed on the display 50? Can decide. With this configuration, even if the measurement value displayed on the display device 50 is a value that is far from the normal measurement value (its own blood pressure value that the subject roughly grasps), the subject can set the value as an abnormal value ( The measurement can be started again without worrying about the value that may be ill). For reference, FIG. 15A illustrates a display example when blood pressure measurement is normally performed without detecting body movement.

  vi) The body movement occurrence location determination unit 66 in FIG. 3 indicates an acceleration signal indicating that there is body movement from the acceleration sensor 23 in at least one of the X-axis direction, the Y-axis direction, and the Z-axis direction. When it is received, it is determined that there is a body movement. Next, the body motion occurrence location determination unit 66 determines whether or not the maximum peak in the generated envelope EV is included in the body motion generation section. Here, the body motion occurrence location determination unit 6 determines in which section of the envelope EV the body motion has occurred.

  Here, the body motion notification unit 68 sets the first threshold level to 20% when the body motion generation location determination unit 66 determines that the maximum peak in the envelope EV is included in the body motion generation section, Set the second threshold level to 50%. When the body motion notification unit 68 determines that the maximum peak in the envelope EV is not included in the body motion generation section by the body motion occurrence location determination unit 66, the first threshold level is set to 30%, Set the second threshold level to 80%. That is, in comparison with the first and second threshold levels when the maximum peak in the envelope is included in the body motion generation section, the maximum peak in the envelope EV is not included in the body motion generation section. 1. The second threshold level is set large. As a result, notification according to the actual measurement accuracy becomes possible.

  vii) Next, as shown in FIGS. 4 and 8, the systolic blood pressure calculation unit 64 in FIG. 3 calculates the point where the portion on the high pressure side of the maximum peak EVP of the envelope EV crosses the systolic blood pressure threshold level Ths. One pressure value Pc1 is calculated as the systolic blood pressure BPsys. Further, as shown in FIGS. 4 and 8, the diastolic blood pressure calculation unit 65 in FIG. 3 is one pressure at a point where the lower pressure side of the maximum peak EVP of the envelope EV crosses the diastolic blood pressure threshold level Thd. The value Pc2 is calculated as the minimum blood pressure BPdia.

  Further, the calculated blood pressure values (maximum blood pressure BPsys and minimum blood pressure BPdia) are displayed on the display 50.

  In this embodiment, the maximum blood pressure threshold level Ths is set to 40% of the value of the maximum peak EVP, and the minimum blood pressure threshold level Thd is set to 50% of the value of the maximum peak EVP. However, the present invention is not limited to this. For example, by changing the ratio of the threshold level to the maximum peak EVP value, the maximum blood pressure threshold level Ths is set to 50% of the maximum peak EVP value, and the minimum blood pressure threshold level Thd is set to 70% of the maximum peak EVP value. Good.

  The operation of the electronic sphygmomanometer 1 configured as described above will be described below.

  FIG. 9 is a flowchart showing blood pressure measurement processing executed by the electronic sphygmomanometer 1 of FIG. In FIG. 9, an electronic sphygmomanometer 1 measures blood pressure according to a general oscillometric method. In addition, this measurement flow is a flow for a comparatively short time which does not need to consider the change of ambient temperature T. At the time of measurement, a cuff is wound around the measurement site (upper arm in this embodiment) of the subject, and the start of measurement is instructed by an operation by the operation unit 52.

  In this electronic sphygmomanometer 1, the CPU 100 measures the blood pressure value of the subject by the oscillometric method according to the flow of FIG. 9.

  Specifically, when the power switch 52A is pressed, the electronic sphygmomanometer 1 starts blood pressure measurement. At the start of blood pressure measurement, the CPU 100 initializes the processing memory area and outputs a control signal to the valve drive circuit 330. Based on the control signal, the valve drive circuit 330 opens the valve 33 and exhausts the air in the fluid bag 22 of the cuff 20. Subsequently, control for adjusting 0 mmHg of the pressure sensor 31 is performed.

  i) When blood pressure measurement is started, first, the CPU 100 closes the valve 33 via the valve drive circuit 330, and then drives the pump 32 via the pump drive circuit 320, and the cuff pressure P is increased by the pressure sensor 31. While observing, control to send air to the fluid bag 22 is performed. As a result, the fluid bag 22 is inflated and the cuff pressure is gradually increased (step S101). When the cuff pressure is increased and reaches the target pressure (set to be higher than the maximum blood pressure of the subject and 150 mmHg in this embodiment) (YES in step S102), the CPU 100 performs pumping via the pump driving circuit 320. 32 is stopped.

  ii) Next, the CPU 100 performs control to gradually open the valve 33 via the valve drive circuit 330. As a result, the fluid bag 22 is contracted and the cuff pressure is gradually reduced (step S103). Here, as for the pressure reduction speed, a target target pressure reduction speed is set during the pressurization of the cuff, and the CPU 100 controls the opening degree of the valve 33 so as to be the target pressure reduction speed.

  iii) In the decompression process in step S103, the CPU 100 generates a pulse wave signal SM from the cuff pressure signal Pc detected by the pressure sensor 31, plots the pulse wave amplitude of the pulse wave signal SM, and sets the envelope EV. Generate (step S104).

  iv) Thereafter, the CPU 100 executes a body motion notification process (step S105), and determines whether or not a body motion error has been detected (step S106).

  FIG. 10 is a flowchart for explaining in detail the body motion notification process in step S105 of FIG. In step S201 in FIG. 10, when the CPU 100 receives an acceleration signal indicating that there is body movement in at least one of the X-axis direction, the Y-axis direction, and the Z-axis direction from the acceleration sensor 23, It is determined that there is movement (YES in step S201), and the process moves to the next step S202. Here, detection of body movement by the acceleration sensor 23 will be described below using graphs.

  FIG. 11 is a time-axis waveform diagram showing changes in the signal levels of the acceleration signals in the X-axis direction, Y-axis direction, and Z-axis direction detected by the acceleration sensor 23 of FIG. 1 with respect to the measurement time, and FIG. It is a time-axis waveform diagram which shows the change of cuff pressure of the cuff 20 for blood pressure measurement. As shown in FIG. 11, when about 10 seconds have passed since the measurement was started, the acceleration signal levels in the X-axis direction, the Y-axis direction, and the Z-axis direction have each changed steeply, and the acceleration sensor 23 Indicates that body movement has been detected.

  FIG. 12 illustrates an envelope EV when body movement is detected. Here, when the section where the body motion flag is 1 is defined as a body motion generation section (part of region A in FIG. 12), it can be understood that the shape of the envelope EV due to body motion is broken in region B. That is, the maximum peak EVP1 of the envelope EV when there is no body movement is shifted to the left to the maximum peak EVP2 of the envelope EV. Therefore, since the maximum peak varies due to body movement, the calculated blood pressure value also varies. This will be described below.

  FIG. 13A shows the blood pressure measurement error ΔE1 when there is no body movement, and FIG. 13B shows the blood pressure measurement error ΔE2 when there is body movement. In FIG. 13A and FIG. 13B, a case will be described in which it is assumed that the threshold level for calculating the maximum blood pressure value is 60% of the maximum pulse wave amplitude value. Here, the reference blood pressure (auscultation value) P1 is a blood pressure value measured by an auscultation method using a stethoscope which is a kind of intermittent method, and a difference from this blood pressure value is regarded as an error.

  In FIG. 13A, it is the pulse wave amplitude maximum value X, and a value (X × 60%) obtained by multiplying this pulse wave amplitude maximum value X by 60% is set as a threshold level for calculating the maximum blood pressure value. The blood pressure calculation output value P2 at which the envelope EV crosses the threshold level is calculated as the maximum blood pressure value. In this case, the blood pressure measurement error ΔE1 = P2−P1.

  In FIG. 13B, it is the pulse wave amplitude maximum value Y, and a value (Y × 60%) obtained by multiplying this pulse wave amplitude maximum value Y by 60% is set as a threshold level for calculating the maximum blood pressure value. A blood pressure calculation output value P3 at which the envelope EV crosses the threshold level is calculated as the maximum blood pressure value. Here, since the shape of the envelope EV collapses due to body movement, the maximum pulse wave amplitude varies. As a result, the blood pressure calculation output value P3 is larger than the blood pressure value calculation value P2. In this case, the blood pressure measurement error ΔE2 = P3-P1.

  As shown in FIGS. 13A and 13B, the blood pressure measurement error ΔE2 is larger than the blood pressure measurement error ΔE1. From this, it can be understood that there is a problem that the blood pressure measurement error measured due to the influence of body movement becomes larger.

  Although the measurement error related to the systolic blood pressure value has been described with reference to FIGS. 13A and 13B, the same applies to the measurement error related to the diastolic blood pressure value.

  In FIG. 12, the value of the maximum peak of the envelope EV increases due to body movement, and an error occurs in the above-described maximum blood pressure threshold level Ths and minimum blood pressure threshold level Thd set by this maximum peak. Therefore, an error also occurs in blood pressure values (maximum blood pressure BPsys and minimum blood pressure BPdia) calculated based on the values of the maximum blood pressure threshold level Ths and the minimum blood pressure threshold level Thd. That is, it is important to determine whether or not the maximum peak of the envelope EV is included in the section where the body motion has occurred.

  Therefore, in step S202 of FIG. 10, the CPU 100 determines whether or not the body motion generation section includes the maximum amplitude value of the pulse wave signal. That is, the CPU 100 determines whether or not the maximum amplitude value is affected by body movement. This determination method will be described below.

  First, an intersection is generated using two points before and after the body motion generation section in the envelope EV. Here, the intersection is an intersection of straight lines passing through the two points. Next, the maximum value of the pulse wave amplitude of the envelope EV is obtained, and when the following equation is established, it is determined that the maximum value of the pulse wave amplitude is included in the body motion generation section. On the other hand, when the following equation is not satisfied, it is determined that the pulse wave amplitude maximum value is not included in the body motion generation section.

  Here, P is the pulse wave amplitude at the intersection point, and Q is the maximum pulse wave amplitude of the envelope EV. Note that the coefficient 1.2 in the equation (1) is a value calculated from an experimental value, and may be another arbitrary real number k.

  14A and 14B are graphs for explaining a method for determining whether or not the maximum amplitude value of the pulse wave signal is included in the body motion generation section in step S202 of FIG. FIG. 14A illustrates a case where the pulse wave amplitude maximum value is included in the body motion generation section, and FIG. 14B illustrates a case where the pulse wave amplitude maximum value is not included in the body motion generation section. In FIG. 14A and FIG. 14B, the dotted lines indicate the envelopes EV when there is no body movement for reference. Here, it can be understood that the shape of the envelope EV is deformed in the body motion generation section.

  FIG. 14A illustrates a case where body movement occurs until the pressure is reduced from the cuff pressure P2 to the cuff pressure P1. Here, the pulse wave amplitude PW2 at the intersection A of the straight line passing through the point B and the next point C at the cuff pressure P1, and the straight line passing through the point D and the previous point E at the cuff pressure P2, and the envelope When the relational expression (1) described above is established between the maximum pulse wave amplitude PW1 of EV and the pulse wave amplitude at point D, the maximum value of the pulse wave amplitude is included in the body motion generation section. To be judged.

  In FIG. 14B, the case where body motion occurs until the pressure is reduced from the cuff pressure P2 to the cuff pressure P1 will be described. Here, the pulse wave amplitude PW2 at the intersection A of the straight line passing through the point B and the next point C at the cuff pressure P1, and the straight line passing through the point D and the previous point E at the cuff pressure P2, and the envelope The relational expression (1) described above is not established with respect to the EV maximum pulse wave amplitude PW1 (pulse wave amplitude at the point F). Therefore, it is determined that the pulse wave amplitude maximum value is not included in the body motion generation section.

  If it is determined in step S202 of FIG. 10 that the maximum amplitude value of the pulse wave signal is included in the body motion generation section (YES in S202), the process proceeds to step S203. In step S203, it is determined whether the body movement section ratio calculated by the CPU 100 is greater than 20% and less than 50%. If it is determined in step S203 that the body motion section ratio is greater than 20% and 50% or less (YES in step S203), a body motion mark is displayed (step S204), and this process ends.

  If it is determined in step S203 that the body motion section ratio is 20% or less or greater than 50% (NO in step S203), the process moves to step S205. In step S205, the CPU 100 determines whether or not the body movement section ratio is greater than 50%. If it is determined in step S205 that the body motion section ratio is greater than 50% (YES in step S205), the process moves to step S208. If it is determined in step S205 that the body motion section ratio is 20% or less (NO in step S205), this process ends.

  If it is determined in step S202 that the body wave generation interval does not include the maximum amplitude value of the pulse wave signal (NO in step S202), the process moves to step S206. In step S206, it is determined whether the body movement section ratio calculated by the CPU 100 is greater than 30% and equal to or less than 80%. If it is determined in step S206 that the body motion section ratio is greater than 30% and 80% or less (YES in step S206), a body motion mark is displayed (step S204), and this process ends.

  If it is determined in step S206 that the body motion section ratio is 30% or less or greater than 80% (NO in step S206), the process moves to step S207. In step S207, the CPU 100 determines whether the body movement section ratio is greater than 80%. If it is determined in step S207 that the body motion section ratio is greater than 80% (YES in S207), the process moves to step S208. If it is determined in S207 that the body motion section ratio is 30% or less (NO in step S207), this process ends.

  In step S208, the CPU 100 detects a body movement that greatly affects the measurement result, stops the blood pressure measurement process (hereinafter referred to as “body movement error”), and notifies the message (body movement error). Display) is displayed on the display 50. That is, the CPU 100 detects a body movement error and displays the fact.

  If a body movement error is detected in step S106 (YES in step S106), the process moves to step S111. If no body movement error is detected (NO in step S106), the process moves to the next step S107.

  v) In step S107, the CPU 100 calculates a blood pressure value (maximum blood pressure and minimum blood pressure) by applying a known algorithm to the acquired data (change in the cuff pressure P due to the pulse wave) by the oscillometric method. When the blood pressure value is calculated and determined (YES in step S108), the CPU 100 displays the calculated blood pressure value on the display 50 (step S109).

  15A to 15C respectively show display examples displayed on the display device 50 in step S109 of FIG. FIG. 15A shows a display example when body movement is not detected during measurement, FIG. 15B shows a display example when body movement is detected during measurement, and FIG. 15C shows during display. A display example when a body movement error is detected is shown.

  vi) Next, the CPU 100 performs control to store the blood pressure value in the memory 51 (step S110), the CPU 100 opens the valve 33 via the valve drive circuit 330, and exhausts the air in the fluid bag 22 of the cuff 20. Control is performed (step S111). Thereafter, when the power switch 52A is pressed, the blood pressure measurement is terminated.

  FIG. 16A shows the measurement error of the systolic blood pressure value measured according to the present invention and the measurement error of the systolic blood pressure value measured by the conventional method. FIG. 16B shows the measurement error of the minimum blood pressure value measured by the present invention and the measurement error of the minimum blood pressure value measured by the conventional method. As shown in FIGS. 16A and 16B, it can be understood that the measurement error is greatly improved as compared to the auscultation method.

  In the above-described embodiment, the measurement site is the arm, but is not limited thereto. The part to be measured may be a wrist or a leg.

  In the above embodiment, the blood pressure is determined while the cuff pressure is being reduced. However, the present invention is not limited to this. The blood pressure may be determined during the pressurization of the cuff pressure.

  The electronic sphygmomanometer of the present invention may measure not only blood pressure values but also other biological information such as a pulse rate.

  The above-described embodiments are merely examples, and various modifications can be made without departing from the scope of the present invention.

  In the present embodiment, when the body motion notification unit 68 determines that the maximum peak in the envelope EV is included in the body motion generation section by the body motion occurrence location determination unit 66, the body motion notification unit 68 sets the first threshold level to 20%. And the second threshold level is set to 50%, and the body movement occurrence location determination unit 66 determines that the maximum peak in the envelope EV is not included in the body movement occurrence section. Although the first threshold level is set to 30% and the second threshold level is set to 80%, the present invention is not limited to this. For example, when the maximum peak in the envelope EV is not included in the body movement occurrence section, the maximum peak in the envelope EV is not included in the body movement generation section as compared to the first and second threshold levels when the maximum peak in the envelope EV is included in the body movement generation section. As long as the first and second threshold levels are set to be large, the first and second threshold levels may be set to other values. Even in this case, the same operation and effect as the present embodiment can be obtained.

DESCRIPTION OF SYMBOLS 1 Electronic sphygmomanometer 10 Main body 20 Cuff 22 Fluid bag 23 Acceleration sensor 31 Pressure sensor 32 Pump 33 Valve 38 Tube 50 Display 51 Memory 52 Operation part 52A Power switch 52B Memory switch 52C Forward switch 52D Return switch 53 Power supply part 61 Pulse wave detection Unit 62 Envelope creation unit 63 Threshold level setting unit 64 Systolic blood pressure calculation unit 65 Diastolic blood pressure calculation unit 66 Body motion occurrence location determination unit 67 Body motion section ratio calculation unit 68 Body motion notification unit 310 Oscillation circuit 320 Pump drive circuit 330 Valve drive Circuit 340 A / D conversion circuit 100 CPU

Claims (4)

An electronic sphygmomanometer that measures the blood pressure of a measurement site,
A cuff pressure control unit that changes the pressure of the cuff attached to the measurement site;
A pressure detector for detecting a cuff pressure signal representing the pressure of the cuff;
A pulse wave detection unit that extracts a pulse wave signal representing the pulse wave of the measurement site superimposed on the cuff pressure signal, and obtains an amplitude sequence indicated by the pulse wave signal;
For the amplitude column acquired by the pulse wave detection unit, an envelope creation unit that creates an envelope that connects the amplitudes; and
An acceleration detection unit that detects body movement of the measurement site and generates an acceleration signal;
Based on the detection result of the acceleration detection unit, a body motion section ratio calculation unit that calculates a body motion section ratio indicating a ratio of a body motion generation section to a section in which the envelope substantially forms a mountain;
An electronic sphygmomanometer, comprising: a body motion notification unit that generates and notifies information indicating the degree of body motion in at least three stages based on the body motion section ratio. The electronic sphygmomanometer according to claim 1,
The body movement notifying unit generates and reports information indicating the degree of body movement in three stages using the first and second threshold levels,
When the body motion section ratio exceeds the second threshold level, the body motion notification unit displays a body motion error indicating that measurement is impossible, and the body motion section ratio is the first section. An electronic sphygmomanometer, wherein a body movement mark indicating that there was a body movement during measurement is displayed when it is greater than the threshold level and below the second threshold level. The electronic blood pressure monitor according to claim 2,
When receiving the acceleration signal from the acceleration detection unit, further comprising a body movement occurrence location determination unit that determines whether the maximum peak in the envelope is included in the body movement generation section,
The electronic sphygmomanometer, wherein the body motion notification unit sets the first and second threshold levels according to a determination result by the body motion occurrence location determination unit. The electronic blood pressure monitor according to claim 3,
The body movement occurrence location determination unit generates intersections using a total of 4 points on each of the left and right sides outside the body movement generation section in the envelope,
When P is the pulse wave amplitude of the intersection, Q is the maximum pulse wave amplitude of the envelope, and k is an arbitrary real number,

An electronic sphygmomanometer that determines that the maximum peak in the envelope is included in the body motion generation section when the following relational expression is satisfied.

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