JP6051744B2 - Electronic blood pressure monitor - Google Patents

Description

  The present invention relates to an electronic blood pressure monitor.

  Blood pressure is one of the indices for analyzing cardiovascular diseases, and risk analysis based on blood pressure is effective in preventing cardiovascular diseases such as stroke, heart failure and myocardial infarction. Conventionally, diagnosis has been performed based on blood pressure (anytime blood pressure) measured at a medical institution such as when visiting a hospital or during a medical examination. However, recent studies have shown that blood pressure measured at home (home blood pressure) is more useful for diagnosis of cardiovascular diseases than blood pressure at any time. Accordingly, blood pressure monitors used at home have become widespread.

  The blood pressure measurement site may be basically any location where the arterial pulse can be touched, but is typically a site such as the upper arm, wrist, ankle, or ankle.

  On the other hand, it is known that the difference between the altitude of the measurement site and the altitude of the heart greatly affects the blood pressure. This is because blood is affected by gravity, and if the difference between the altitude of the measurement site and the altitude of the heart is 10 cm, a measurement error due to a water head pressure of about 8 mmHg occurs. Therefore, it is necessary to pay attention to the altitude of the measurement site, particularly when measuring blood pressure using the wrist, ankle, and foot sole as the measurement site.

  As a method for eliminating a measurement error caused by the difference between the altitude of the measurement site and the altitude of the heart, a method of guiding the measurement site to the altitude of the heart is known (for example, see Patent Document 1). In this method, the posture of the measurement site is acquired by an acceleration sensor or the like, the difference between the height of the measurement site and the altitude of the heart is detected from the angle information, and the measurement site is guided to the altitude of the heart.

  As another method for eliminating the measurement error due to the difference between the altitude of the measurement site and the altitude of the heart, a method of detecting the altitude of the measurement site and correcting the blood pressure value is known (see, for example, Patent Document 2). ). In the blood pressure correction method described in Patent Document 2, an absolute pressure sensor (atmospheric pressure sensor) is provided in the vicinity of the cuff, the altitude of the measurement site is detected by a change in atmospheric pressure, and an error due to hydraulic head pressure is detected from the detected altitude information. The amount of correction is calculated. This is the same principle used in altimeters.

JP 2007-054648 A JP 2011-104073 A

  As described above, since the difference between the altitude of the measurement site and the altitude of the heart is 10 cm and a hydraulic head pressure of about 8 mmHg is generated, in the blood pressure correction method using the absolute pressure sensor, for example, to suppress the measurement error to 4 mmHg or less. The height resolution needs to be 5 cm or less. Since the atmospheric pressure changes 100 hPa at 1000 m, the pressure resolution of the absolute pressure sensor needs to be 0.5 Pa or less in order to detect a height of 5 cm.

  An absolute pressure sensor having a pressure resolution of 0.5 Pa or less exists on the market, but generally, the sensor output includes a drift error of the sensor. Depending on the absolute pressure sensor, a drift of ± 30 Pa may occur even if the ambient environment such as temperature and pressure is constant. An error of ± 30 Pa corresponds to an error of ± 3 m in terms of height. The accuracy is sufficient for use as an altimeter, but the accuracy is insufficient for detecting the altitude of the measurement site in the sphygmomanometer. This drift can be even greater depending on the surrounding environment such as temperature and pressure.

  Therefore, it is conceivable to correct the drift of the absolute pressure sensor, but it is not possible to determine whether the drift has occurred or the altitude of the measurement site has changed with only the output of the absolute pressure sensor. Can not.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to appropriately detect the altitude of a blood pressure measurement site of a person to be measured and increase blood pressure measurement accuracy.

A measurement unit that measures blood pressure at a blood pressure measurement site of the measurement subject, a first altitude sensor that detects an altitude of the blood pressure measurement site, a first displacement sensor that detects a displacement in the height direction of the blood pressure measurement site, Based on the first displacement information detected by the first displacement sensor, a correction unit that performs drift correction on the first height information detected by the first height sensor, and the first processed by the correction unit An electronic sphygmomanometer, comprising: an altitude difference calculating unit that calculates an altitude difference between the blood pressure measurement site and the heart of the subject using altitude information.

  According to the present invention, it is possible to appropriately detect the altitude of the blood pressure measurement site of the measurement subject, and to increase blood pressure measurement accuracy.

It is a figure which shows the structure of an example of the electronic blood pressure meter for demonstrating embodiment of this invention. It is a figure which shows an example of the use condition of the electronic blood pressure monitor of FIG. It is a functional block diagram of the electronic blood pressure monitor of FIG. It is a graph which shows an example of a pulse wave and a pulse wave amplitude at the time of reducing pressure gradually in a blood pressure measurement part. It is a graph for demonstrating the blood-pressure measurement method by the electronic sphygmomanometer of FIG. It is a flowchart of the blood pressure measurement using the electronic sphygmomanometer of FIG. It is a flowchart of the drift correction process of the height sensor in the flow of the blood pressure measurement of FIG. It is a graph which shows the correction method of the hydraulic head pressure in the modification of the electronic blood pressure monitor of FIG. It is a functional block diagram of the other example of the electronic blood pressure monitor for demonstrating embodiment of this invention. It is a graph for demonstrating the blood-pressure measuring method by the electronic blood pressure monitor of FIG. It is a functional block diagram of the other example of the electronic blood pressure monitor for demonstrating embodiment of this invention. It is a flowchart of the blood pressure measurement using the electronic blood pressure monitor of FIG. It is a functional block diagram of the other example of the electronic blood pressure monitor for demonstrating embodiment of this invention. It is a flowchart of the blood pressure measurement by the electronic blood pressure monitor of FIG.

  FIG. 1 shows a configuration of an example of an electronic sphygmomanometer for explaining an embodiment of the present invention, and FIG. 2 shows an example of a usage state of the electronic sphygmomanometer of FIG.

  The electronic sphygmomanometer 1 measures blood pressure by an oscillometric method. The measurement of blood pressure by the oscillometric method is to detect the pulse wave at the blood pressure measurement site in the process of compressing the blood pressure measurement site of the subject and gradually reducing the pressure of the blood pressure measurement unit, and change the pulse wave amplitude. Based on this, the blood pressure is determined using a predetermined algorithm.

  The electronic sphygmomanometer 1 includes a cuff 2 attached to a blood pressure measurement site of a measurement subject and a sphygmomanometer body 4. In the example shown in FIG. 2, the blood pressure measurement site of the subject is the wrist, and the posture of the subject is in a sitting position with the tip of the elbow placed on a table such as a table. The arm may be an upper arm, an ankle, or ankle, and the posture of the person to be measured may be a state where the arm is suspended in a sitting position, or may be a lying position or a standing position.

  The cuff 2 includes a fluid bag 10 that is inflated and contracted by the pressure medium using a fluid such as air as a pressure medium, holds the wrist, and compresses the wrist by the expansion and contraction of the fluid bag 10.

  The cuff 2 is connected to the sphygmomanometer body 4 by a cord 5 including a pipe for circulating the pressure medium, and the sphygmomanometer body 4 is provided with a pump for supplying the pressure medium to the fluid bag of the cuff 2. . The fluid bag 10 is supplied with a pressure medium from the sphygmomanometer body 4 via the cord 5 and expands and contracts.

  The cuff 2 is provided with a height sensor for detecting the height of the wrist to which the cuff 2 is attached and a displacement sensor for detecting the displacement of the wrist in the height direction. In the electronic sphygmomanometer 1, the height sensor is an absolute pressure sensor (barometric pressure sensor) 14, and the displacement sensor is an acceleration sensor 15.

  Output signals from the absolute pressure sensor 14 and the acceleration sensor 15 are exchanged with the sphygmomanometer body 4 via the cord 5.

  FIG. 3 shows functional blocks of the electronic sphygmomanometer 1.

  The electronic sphygmomanometer 1 includes a measurement unit 20 that measures blood pressure at a blood pressure measurement site of the measurement subject, a display unit 21 that displays a blood pressure value and the like obtained by the measurement, and an operation for operating start / stop of blood pressure measurement. A unit 22 and a power source unit 23 are provided, and these are provided in the blood pressure monitor main body 4.

  The measurement unit 20 includes a CPU (Central Processing Unit) 30 that controls the blood pressure measurement operation of the electronic sphygmomanometer 1, a first memory 31 that functions as a work memory of the CPU 30, a program executed by the CPU 30, and the measurement subject's It includes a second memory 32 that stores various information such as height information and blood pressure values obtained by measurement, a pressure adjustment unit 33 that adjusts the pressure in the fluid bag 10 of the cuff 2, and a timer 34. The CPU 30 controls the overall operation of the electronic sphygmomanometer 1 as well as the blood pressure measurement operation.

  The display unit 21 includes a display device 35 such as a liquid crystal display, and displays the blood pressure value and the like on the display device 35 under the control of the CPU 30.

  The operation unit 22 is a power switch 36 that is operated to switch on / off the power supply to the electronic sphygmomanometer 1, and a measurement switch 37 that is operated to instruct the start / stop of the blood pressure measurement operation of the electronic sphygmomanometer 1. A setting switch 38 that is operated to input information such as the height information of the person to be measured to the electronic sphygmomanometer 1, and a recording call switch 39 that is operated to call various information stored in the second memory 32. Including.

  The pressure adjusting unit 33 includes a pressure sensor 40 for detecting the internal pressure of the fluid bag 10 of the cuff 2, an oscillation circuit 41 that converts the output of the pressure sensor 40 into a frequency and inputs the frequency to the CPU 30, and the fluid bag 10 of the cuff 2. A pump 42 for supplying pressure medium to the pump, a pump drive circuit 43 for driving the pump 42, a valve 44 for opening and closing to discharge or confine the pressure medium in the fluid bag 10 of the cuff 2, and a valve for driving the valve 44 Drive circuit 45.

  The CPU 30 converts the oscillation frequency signal input from the oscillation circuit 41 into pressure to detect the pressure in the fluid bag 10, and the compression pressure of the cuff 2 (hereinafter referred to as “cuff pressure”) is a desired pressure. Thus, the pump drive circuit 43 and the valve drive circuit 45 are controlled.

  Further, the electronic sphygmomanometer 1 uses a correction unit that performs drift correction on the output signal of the absolute pressure sensor 14, and the blood pressure measurement unit and the device under measurement using the output signal of the absolute pressure sensor 14 processed by the correction unit. A calculation unit that calculates a difference in altitude from the person's heart, and these functions are realized by the CPU 30.

  Furthermore, CPU30 correct | amends the hydrocephalic pressure resulting from the altitude difference of a blood pressure measurement site | part and the heart with respect to the blood pressure in a blood pressure measurement site | part, and calculates the blood pressure in the height of the heart as a to-be-measured person's blood pressure.

  FIG. 4 shows an example of the pulse wave and pulse wave amplitude obtained in the process of gradually reducing the cuff pressure in blood pressure measurement by the oscillometric method, and FIG. 5 shows a method for determining the blood pressure of the measurement subject by the oscillometric method. Show.

  When the cuff pressure becomes higher than the maximum blood pressure of the measurement subject, hemostasis is stopped, and blood flow is resumed by gradually reducing the cuff pressure. In the oscillometric method, blood pressure is measured by using a characteristic that the pulse wave amplitude changes as shown in FIG. 4 in the process of gradually reducing the cuff pressure.

As shown in FIG. 5, first, the cuff pressure is increased to a pressure PC ₀ that is equal to or higher than the maximum blood pressure of the measurement subject, and then reduced at a constant rate (for example, 2 to 3 mmHg / sec). In the process of gradually reducing the cuff pressure, a predetermined algorithm is applied to the pulse wave amplitude detected by the pressure sensor 40 while being superimposed on the cuff pressure to determine the maximum blood pressure and the minimum blood pressure.

Specifically, the threshold TH _SBP is a value obtained by multiplying the pulse wave amplitude at the pulse wave amplitude maximum point A _max where the pulse wave amplitude is maximized in the process of reducing the cuff pressure by a constant (for example, 0.5), A value obtained by multiplying the maximum point A _max by a constant (for example, 0.7) is set as a threshold TH _DBP , and a pulse wave amplitude maximum point A _max corresponding to a point where the envelope C of the pulse wave amplitude and the threshold TH _SBP intersect is detected. A cuff pressure higher than the measured cuff pressure is determined as the maximum blood pressure SBP, and the cuff pressure lower than the cuff pressure at which the pulse wave amplitude maximum point A _max corresponding to the point where the envelope C and the threshold TH _DBP intersect is detected is the minimum blood pressure. DBP is determined.

  FIG. 6 shows a blood pressure measurement flow using the electronic sphygmomanometer 1.

  First, the power switch 36 is operated by the measurement subject or other operators (step ST1). Thereby, in the electronic sphygmomanometer 1, initialization is performed by the CPU 30 (step ST2). The initialization includes processes such as initialization of the first memory 31, discharge of the pressure medium in the fluid bag 10 of the cuff 2, correction of 0 mmHg of the pressure sensor 40, and the like.

  After initialization, the CPU 30 starts drift correction processing for the absolute pressure sensor 14 (step ST3). The drift correction process of the absolute pressure sensor 14 is continued until the electronic sphygmomanometer 1 is turned off. The drift correction process will be described later.

  Next, the height information of the person to be measured is set in the electronic sphygmomanometer 1 by the operator (step ST4). If the height information of the person to be measured is not stored in the second memory, the height information is set by inputting the height information by operating the setting switch 38, and the height information of the person to be measured is stored in the second memory. Is stored, the corresponding height information stored in the second memory is called and set by operating the record call switch 39.

After the height information is set, the measurement subject takes a predetermined basic posture when measuring blood pressure in the sitting position with the wrist as a blood pressure measurement site (step ST5). In this state, the CPU 30 calculates the atmospheric pressure at the altitude of the blood pressure measurement site based on the atmospheric pressure signal subjected to the drift correction processing of the absolute pressure sensor 14 provided in the cuff 2, and sets the calculated atmospheric pressure to the reference pressure PA ₀ . Determine (step ST6).

  As a basic posture for measuring blood pressure in the sitting position with the wrist as a blood pressure measurement site, for example, as shown by a broken line in FIG. 2, the arm can be suspended.

When the measurement switch 37 is pressed by the operator after the reference pressure PA ₀ is determined (step ST7), the electronic sphygmomanometer 1 executes a blood pressure measurement operation by the oscillometric method under the control of the CPU 30. . The posture of the person under measurement during the measurement period is arbitrary, for example, the basic posture described above, or a posture in which the tip of the elbow is placed on a table or the like as shown by a solid line in FIG. You can also

First, the CPU 30 operates the pump 42 to increase the cuff pressure PC to a pressure PC ₀ that is equal to or higher than the highest blood pressure of the measurement subject (steps ST8 to ST9).

After increasing the cuff pressure PC to the pressure PC ₀ , the CPU 30 stops the pump 42 (step ST10), and the CPU 30 opens the valve 44 to reduce the cuff pressure PC at a constant speed (step ST11). .

  In the process of reducing the cuff pressure PC, the CPU 30 sequentially acquires the pressure signal output from the pressure sensor 40, and determines the blood pressure at the blood pressure measurement site by the oscillometric method from the acquired pressure signal (step ST12).

  Specifically, the CPU 30 discriminates the cuff pressure, which is a steady pressure component included in the pressure signal, and the pulse wave, which is a vibration component included in the pressure signal, by filtering, and the pulse wave from the discriminated pulse wave Detect amplitude.

Then, as described above, the CPU 30 detects the pulse wave amplitude maximum point A _max , sets a value obtained by multiplying the pulse wave amplitude at the maximum point A _max by a constant as a threshold TH _SBP, and multiplies the maximum point A _max by a constant. as threshold values TH _DBP, corresponding to the point of intersection and the envelope C and the threshold TH _SBP of the pulse wave amplitude, the higher cuff pressure than the cuff pressure detected pulse wave amplitude maximum point a _max is determined systolic blood pressure SBP Further, a cuff pressure lower than the cuff pressure at which the pulse wave amplitude maximum point A _max is detected, corresponding to the point where the envelope C and the threshold TH _DBP intersect, is determined as the minimum blood pressure DBP (see FIG. 5).

  The CPU 30 determines whether or not the blood pressure (maximum blood pressure and minimum blood pressure) has been determined (step ST13), continues the cuff pressure reduction control and the blood pressure determination processing until the blood pressure is determined, and determines the blood pressure. Thereafter, the valve 44 is completely opened to discharge the pressure medium in the fluid bag 10 of the cuff 2 (step ST14).

Next, the CPU 30 calculates the altitude difference h ₁ (see FIG. 2) between the blood pressure measurement site and the heart in the posture during the measurement period (step ST15).

Specifically, CPU 30, based on the drift correction processed pressure signal of the absolute pressure sensor 14 provided in the cuff 2, calculates the pressure at altitude of the blood pressure measurement site, calculated pressure PA ₁ and the reference pressure Based on the difference from PA ₀ , a change amount Δ _h (see FIG. 2) of the altitude of the blood pressure measurement site between the posture during the measurement period and the reference posture is calculated.

Then, the CPU 30 calculates an altitude difference h ₀ (see FIG. 2) between the blood pressure measurement part and the heart in the reference posture from the height information set in the electronic sphygmomanometer 1 in step ST4. The second memory 32 stores in advance a data table in which the height and the average height difference in the reference posture are associated with each other, and the CPU 30 refers to this data table and sets the set height information. to calculate the difference _{h 0} in response.

Then, CPU 30 subtracts a high degree of variation delta _h of the blood pressure measurement site between the attitude and the reference attitude during the measurement period from the difference h ₀ computed blood pressure measurement site and the heart of the posture during the measurement period calculating the altitude difference h ₁ between.

After calculating the altitude difference h ₁ between the blood pressure measurement site and the heart in the posture during the measurement period (the altitude of the blood pressure measurement site—the altitude of the heart), the CPU 30 determines in step ST12 based on this difference h ₁ . The head pressure is corrected according to the following equation (1) for the blood pressure at the blood pressure measurement site (maximum blood pressure SBP, minimum blood pressure DBP), and the blood pressure at the heart altitude (maximum blood pressure SBP ′, minimum blood pressure DBP) ') Is calculated (step ST16).

  Then, the CPU 30 displays the calculated blood pressure value on the display device 35 and stores it in the second memory 32 (step ST17), and ends the blood pressure measurement operation of the electronic sphygmomanometer 1.

  FIG. 7 shows a flow of drift correction processing of the absolute pressure sensor 14.

  First, the CPU 30 acquires an atmospheric pressure signal output from the absolute pressure sensor 14 (step ST101), and acquires an acceleration signal output from the acceleration sensor 15 (step ST102).

Next, the CPU 30 compares the difference Δ _PA between the atmospheric pressure signal acquired in step ST101 and the previously acquired atmospheric pressure signal with a predetermined threshold TH _PA (step ST103).

When the difference Δ _PA is equal to or less than the threshold value TH _PA , the CPU 30 determines that drift correction is not necessary and ends the process.

On the other hand, when the difference Δ _PA exceeds the threshold value TH _PA , the CPU 30 compares the difference Δ _ACC between the acceleration signal acquired in step ST102 and the acceleration signal acquired last time with a predetermined threshold value TH _ACC (step ST104). .

When the difference Δ _ACC is equal to or greater than the threshold TH _ACC , the CPU 30 determines that the difference Δ _PA is due to the displacement of the absolute pressure sensor 14, that is, the displacement of the blood pressure measurement site, determines that drift correction is not necessary, and ends the process. To do.

On the other hand, when the difference Δ _ACC is less than the threshold value TH _ACC , the CPU 30 has no displacement in the height direction of the blood pressure measurement site, and the difference Δ _PA is due to the drift of the absolute pressure sensor 14 and requires drift correction. Judgment is made and drift correction is executed (step ST105).

Drift correction can be performed by, for example, the difference delta _PA when the drift correction is determined necessary to accumulate at the step ST 104, is subtracted from the pressure signal values acquired its accumulated value.

In the blood pressure measurement flow using the electronic sphygmomanometer 1 described above, the atmospheric pressures PA ₀ and PA ₁ calculated in each of the steps ST5 and ST14 are appropriately removed from the influence of drift by the above-described drift correction processing. It is calculated based on the reduced atmospheric pressure signal of the absolute pressure sensor 14, and therefore the altitude of the blood pressure measurement site between the posture during the measurement period calculated from these atmospheric pressures PA ₀ and PA ₁ and the reference posture. it is possible to enhance the accuracy of the amount of change delta _h. Thereby, the accuracy of the hydrocephalic pressure based on the altitude difference h ₁ and the altitude difference h ₁ between the blood pressure measurement site and the heart in the posture during the measurement period can be increased, and consequently the blood pressure measurement accuracy can be increased.

  In the above description, the blood pressure is measured in the sitting position with the wrist as the blood pressure measurement site. However, as described above, the blood pressure measurement site may be the upper arm, the ankle, or the back of the foot. The posture may be recumbent or standing. Accordingly, the above-mentioned reference posture is determined according to the combination of the blood pressure measurement unit and the posture, and a data table is prepared in which the height and the average height difference between the reference postures are associated with each other, and the height information of the measurement subject is prepared. The blood pressure measurement unit and posture may be set together with the above setting.

  FIG. 8 shows a method of correcting the hydraulic head pressure in the modified example of the electronic blood pressure monitor 1 described above.

The head pressure correction described above determines the blood pressure at the blood pressure measurement site, and adds the head pressure corresponding to the altitude difference h ₁ between the blood pressure measurement site and the heart in the posture during the measurement period to the determined blood pressure. In the example shown in FIG. 8, the head pressure correction is performed by changing the threshold applied to the envelope C of the pulse wave amplitude in accordance with the altitude difference h ₁ between the blood pressure measurement site and the heart. To calculate the blood pressure at the heart altitude (maximum blood pressure SBP ′, minimum blood pressure DBP ′) as the blood pressure of the measurement subject.

Specifically, as shown in the following equation (2), for the threshold used for determining the systolic blood pressure, the threshold enough to altitude difference h ₁ of blood pressure measurement site and the heart is reduced from a positive value over a negative value multiplied by the difference between _{h 1} constant alpha ₁ increase, the value is added to the threshold value _{TH SBP} above, the threshold value _{TH SBP} 'to be applied to the envelope C. As for the threshold used for determining the minimum blood pressure, the difference h ₁ is multiplied by a constant α ₂ that decreases the threshold as the altitude difference h ₁ between the blood pressure measurement site and the heart decreases from a positive value to a negative value. The value is added to the above-mentioned threshold value TH _DBP to obtain a threshold value TH _DBP ′ applied to the envelope C.

The threshold values TH _SBP ′ and TH _DBP ′ thus obtained are applied to the envelope C, and the cuff pressure obtained by detecting the pulse wave amplitude maximum point A _max corresponding to the point where the envelope C of the pulse wave amplitude and the threshold TH _SBP intersect. A higher cuff pressure is set as the systolic blood pressure SBP ′, and a cuff pressure lower than the cuff pressure at which the pulse wave amplitude maximum point A _max corresponding to the point where the envelope C and the threshold TH _DBP intersect is detected as the diastolic pressure DBP ′. .

Example shown in FIG. 8, the altitude difference h ₁ is a negative value of the blood pressure measurement site and the heart of the posture during the measurement period, i.e. there blood pressure measurement site is at a position lower than the heart, blood pressure in the blood pressure measurement site heart The head pressure is corrected by applying the thresholds TH _SBP ′ (> TH _SBP ), TH _DBP ′ (<TH _DBP ) to the envelope C, The blood pressure at the altitude of the heart (maximum blood pressure SBP ', minimum blood pressure DBP') is calculated as the blood pressure.

  FIG. 9 shows functional blocks of another example of an electronic blood pressure monitor for explaining the embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the element which is common in the electronic blood pressure monitor 1 mentioned above, and description is abbreviate | omitted or simplified.

  Although the above-described electronic sphygmomanometer 1 has been described as measuring blood pressure by the oscillometric method, the electronic sphygmomanometer 101 shown in FIG. 9 measures blood pressure by the Korotkoff method. The electronic sphygmomanometer 101 includes a microphone 116 for detecting a Korotkoff sound corresponding to the sound of blood flow hitting the artery wall, and this microphone is provided in the cuff 2.

  FIG. 10 shows a method for determining blood pressure in blood pressure measurement by the Korotkoff method.

  When the cuff pressure becomes higher than the maximum blood pressure of the measurement subject, the blood is stopped, and the blood flow is resumed by gradually reducing the cuff pressure. The Korotkoff method detects the Korotkoff sound that occurs in the process of gradually reducing the cuff pressure. Based on this, the blood pressure is calculated.

First, the cuff pressure is increased to a pressure PC ₀ that is equal to or higher than the maximum blood pressure of the measurement subject, and then reduced at a constant rate. When the sound pressure _{exceeding the} predetermined threshold TH _SBP is detected by the microphone 16, that is, when the Korotkoff sound is detected for the first time, the cuff pressure is determined to be the highest blood pressure SBP, and then the Korotkoff sound that has been continuously detected disappears , i.e. to determine the cuff pressure at the time the sound pressure of the sound detected by the microphone 16 is less than a predetermined threshold value TH _DBP in diastolic blood pressure DBP.

In this electronic sphygmomanometer 101 as well as the above-described electronic sphygmomanometer 1, the blood pressure at the blood pressure measurement site (maximum blood pressure SBP, minimum blood pressure DBP) is determined, and the determined blood pressure is measured between the blood pressure measurement site and the heart. The hydraulic head pressure can be corrected by adding the hydraulic head pressure corresponding to the altitude difference h ₁ , and the threshold values TH _SBP and TH _DBP can be changed according to the altitude difference h ₁ between the blood pressure measurement site and the heart. Pressure correction can also be performed.

  FIG. 11 shows another example functional block of an electronic sphygmomanometer for explaining an embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the element which is common in the electronic blood pressure monitor 1 mentioned above, and description is abbreviate | omitted or simplified.

  An electronic sphygmomanometer 201 shown in FIG. 11 is attached to the chest of the measurement subject, and includes an absolute pressure sensor 214 for detecting the altitude of the chest (heart) and an acceleration sensor 215 for detecting displacement in the height direction of the chest. It has.

The CPU 30 performs drift correction on the output signal of the absolute pressure sensor 14 and the output signal of the absolute pressure sensor 214, and based on the output signals of the absolute pressure sensors 14 and 214 subjected to the drift correction processing, the blood pressure measurement unit and the measurement subject. An altitude difference h _{1 from the} heart (see FIG. 2) is calculated.

  FIG. 12 shows a flow of blood pressure measurement using the electronic sphygmomanometer 201.

  First, the power switch 36 is operated by the measurement subject or other operators (step ST201). Thereby, in electronic sphygmomanometer 1, initialization is performed by CPU30 (step ST202).

  After initialization, the CPU 30 starts drift correction processing for the absolute pressure sensors 14, 214 (step ST203). The drift correction process is the same as the drift correction process of the absolute pressure sensor 14 in the electronic sphygmomanometer 1 described above.

  When the measurement switch 37 is pressed by the operator (step ST204), the blood pressure measurement operation by the oscillometric method is executed in the electronic sphygmomanometer 1 under the control of the CPU 30. The posture of the person under measurement during the measurement period is arbitrary, for example, the basic posture described above, or a posture in which the tip of the elbow is placed on a table or the like as shown by a solid line in FIG. You can also

First, the CPU 30 operates the pump 42 to increase the cuff pressure PC to a pressure PC ₀ that is equal to or higher than the maximum blood pressure of the person to be measured (steps ST205 to ST206).

After increasing the cuff pressure PC to the pressure PC ₀ , the CPU 30 stops the pump 42 (step ST207), and the CPU 30 opens the valve 44 to reduce the cuff pressure PC at a constant speed (step ST208). .

  In the process of reducing the cuff pressure PC, the CPU 30 sequentially acquires the pressure signal output from the pressure sensor 40, and determines the blood pressure at the blood pressure measurement site by the oscillometric method from the acquired pressure signal (step ST209).

  The CPU 30 determines whether or not the blood pressure (maximum blood pressure and minimum blood pressure) has been determined (step ST210), and continues the cuff pressure reduction control and the blood pressure determination processing until the blood pressure is determined to determine the blood pressure. Thereafter, the valve 44 is completely opened to discharge the pressure medium in the fluid bag 10 of the cuff 2 (step ST211).

Next, the CPU 30 calculates an altitude difference h ₁ (see FIG. 2) between the blood pressure measurement site and the heart in the posture during the measurement period (step ST212).

Here, the CPU 30 uses the atmospheric pressure signal subjected to the drift correction process of the absolute pressure sensor 14 provided in the cuff 2 and the atmospheric pressure signal subjected to the drift correction process of the absolute pressure sensor 214 attached to the chest of the measurement subject. Then, the difference between the atmospheric pressure at the altitude of the blood pressure measurement site and the atmospheric pressure at the altitude of the chest (heart) is calculated, and the altitude difference h ₁ between the blood pressure measurement site and the heart is calculated based on the calculated atmospheric pressure difference.

After calculating the altitude difference h ₁ between the blood pressure measurement site and the heart (the altitude of the blood pressure measurement site—the altitude of the heart), the CPU 30 determines the blood pressure (maximum) in the blood pressure measurement site determined in step ST209 based on the difference h _1. The head pressure is corrected for the high blood pressure SBP and the minimum blood pressure DBP), and the blood pressure at the altitude of the heart as the blood pressure of the measurement subject is calculated (step ST213).

As described in the electronic sphygmomanometer 1 described above, the hydraulic head pressure correction determines the blood pressure at the blood pressure measurement site, and sets the water head pressure corresponding to the altitude difference h ₁ between the blood pressure measurement site and the heart with respect to the determined blood pressure. The threshold value can be added, or the threshold value can be changed according to the altitude difference h ₁ between the blood pressure measurement site and the heart.

  Then, the CPU 30 displays the calculated blood pressure value on the display device 35 and stores it in the second memory 32 (step STST214), and the blood pressure measurement operation of the electronic sphygmomanometer 201 is terminated.

According to the electronic sphygmomanometer 201, the altitude between the blood pressure measurement site and the heart is calculated from the atmospheric pressure signal of the absolute pressure sensor 14 provided in the cuff 2 and the atmospheric pressure signal of the absolute pressure sensor 215 attached to the chest of the subject. it is possible to calculate the difference between h ₁ directly, it is possible to omit the step of reference attitude is taken by the subject, it is possible to improve convenience.

  The electronic sphygmomanometer 201 has been described as measuring blood pressure by the oscillometric method. However, similarly to the electronic sphygmomanometer 101 described above, the cuff 2 is provided with a microphone and configured to measure blood pressure by the Korotkoff method. You can also

  FIG. 13 shows another example functional block of an electronic sphygmomanometer for explaining an embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the element which is common in the electronic blood pressure monitor 1 mentioned above, and description is abbreviate | omitted or simplified.

Electronic blood pressure monitor 1, 101, and 201 described above, both to calculate the altitude difference h ₁ between the blood pressure measurement unit and the heart, but is intended to correct the water head pressure caused by the height difference h _1, FIG. 13 ₁ calculates an altitude difference h ₁ between the blood pressure measurement unit and the heart, and guides the blood pressure measurement site to the altitude of the heart based on the altitude difference h ₁ .

In the electronic sphygmomanometer 301, as in the electronic sphygmomanometer 1 described above, the CPU 30 performs drift correction on the output signal of the absolute pressure sensor 14, and uses the output signal of the absolute pressure sensor 14 subjected to drift correction processing. calculating the altitude difference h ₁ between the heart of the blood pressure measuring portion and the measured person.

Then, CPU 30 may display the altitude difference h ₁ for example, the display device 35 of the display unit 21, a blood pressure measurement site highly guide heart. Instead of the guide based on the display of the display device 35, a speaker may be provided in the sphygmomanometer body 4 and guided by voice.

  FIG. 14 shows a blood pressure measurement flow using the electronic sphygmomanometer 301.

  First, the power switch 36 is operated by the measurement subject or other operators (step ST301). Thereby, in electronic blood pressure monitor 1, initialization is performed by CPU30 (step ST302).

  After initialization, the CPU 30 starts drift correction processing for the absolute pressure sensor 14 (step ST303). The drift correction process is the same as the drift correction process of the absolute pressure sensor 14 in the electronic sphygmomanometer 1 described above.

  Next, the height information of the person to be measured is set in the electronic sphygmomanometer 1 by the operator (step ST304).

After the height information is set, the measurement subject takes a predetermined basic posture when measuring blood pressure in the sitting position with the wrist as the blood pressure measurement site (step ST305). In this state, the CPU 30 calculates the atmospheric pressure at the altitude of the blood pressure measurement site based on the atmospheric pressure signal subjected to the drift correction processing of the absolute pressure sensor 14 provided in the cuff 2, and sets the calculated atmospheric pressure to the reference pressure PA ₀ . Determine (step ST306).

After the reference pressure PA ₀ is determined, the CPU 30 calculates an altitude difference h ₁ between the blood pressure measurement unit and the measured person's heart (step ST307).

Specifically, the CPU 30 calculates the atmospheric pressure PA ₁ at the altitude of the blood pressure measurement site based on the atmospheric pressure signal subjected to the drift correction processing of the absolute pressure sensor 14 provided in the cuff 2, and the calculated atmospheric pressure PA ₁ Based on the difference from the reference pressure PA ₀ , an altitude change amount Δ _h (see FIG. 2) of the blood pressure measurement site is calculated.

Then, the CPU 30 calculates an altitude difference h ₀ (see FIG. 2) between the blood pressure measurement part and the heart in the reference posture from the height information set in the electronic sphygmomanometer 1 in step ST4. The second memory 32 stores in advance a data table in which the height and the average height difference in the reference posture are associated with each other, and the CPU 30 refers to this data table and sets the set height information. to calculate the difference _{h 0} in response.

Then, CPU 30, from the difference h ₀ which is calculated by subtracting the altitude variation delta _h of the blood pressure measurement site, to calculate the altitude difference h ₁ of blood pressure measurement site and the heart.

After calculating the altitude difference _{h 1} of blood pressure measurement site and the heart, CPU 30 compares the absolute value of the altitude difference _{h 1} with a predetermined threshold value TH _h (step ST 308).

If altitude difference h ₁ is greater than the threshold TH _h, CPU 30 may display the height difference h ₁ on the display unit 35 of the display unit 22, a high degree of blood pressure measurement site guides to match high degree of heart (step ST309). CPU30 until altitude difference _{h 1} is equal to or less than the threshold TH _h, repeated calculation and guide treatment of the altitude difference _{h 1} above (the step ST307~ST309).

After altitude difference _{h 1} is equal to or less than the threshold value TH _h, when the measurement switch 37 by the operator is pressed (step ST 310), the electronic blood pressure monitor 301, under the control of the CPU 30, the blood pressure measuring operation by the oscillometric method Is executed.

First, the CPU 30 operates the pump 42 to increase the cuff pressure PC to a pressure PC ₀ that is equal to or higher than the maximum blood pressure of the person to be measured (steps ST311 to ST312).

After increasing the cuff pressure PC to the pressure PC ₀ , the CPU 30 stops the pump 42 (step ST313), and the CPU 30 opens the valve 44 to reduce the cuff pressure PC at a constant speed (step ST314). .

  Then, in the process of reducing the cuff pressure PC, the CPU 30 sequentially acquires the pressure signal output from the pressure sensor 40, and determines the blood pressure at the blood pressure measurement site by the oscillometric method from the acquired pressure signal (step ST315).

  The CPU 30 determines whether or not the blood pressure (maximum blood pressure and minimum blood pressure) has been determined (step ST316), and continues the cuff pressure reduction control and the blood pressure determination processing until the blood pressure is determined to determine the blood pressure. Thereafter, the valve 44 is completely opened to discharge the pressure medium in the fluid bag 10 of the cuff 2 (step ST317).

  Then, the CPU 30 displays the calculated blood pressure value on the display device 35 and stores it in the second memory 32 (step ST318), and the blood pressure measurement operation of the electronic sphygmomanometer 301 is ended.

  In this electronic sphygmomanometer 301, the blood pressure is measured in a state where the altitude of the blood pressure measurement site matches the altitude of the heart, so the blood pressure at the blood pressure measurement site and the blood pressure at the altitude of the heart match, and the head pressure correction is performed. Do not do.

According to the electronic blood pressure monitor 301, the influence of drift are calculated altitude difference h ₁ of blood pressure measurement site and the heart based on suitably removed to mitigated pressure signal of the absolute pressure sensor 14, the altitude difference h it is possible to enhance the precision of _1, a high degree of blood pressure measurement site can be matched well highly accurate heart by a guide based on the altitude difference h _1. Thereby, the blood pressure measurement accuracy can be increased.

The electronic sphygmomanometer 301 has been described as measuring blood pressure by the oscillometric method. However, similarly to the electronic sphygmomanometer 101 described above, a microphone is provided in the cuff 2 and blood pressure is measured by the Korotkoff method. You can also. Similarly to the electronic sphygmomanometer 201 described above, an absolute pressure sensor and an acceleration sensor to be worn on the chest of the measurement subject are provided, and an atmospheric pressure signal of the absolute pressure sensor 14 provided on the cuff 2 and the chest of the measurement subject. absolute mounted from pressure signals of the pressure sensor can also be configured to calculate the altitude difference h ₁ of blood pressure measurement site and the heart directly.

  As described above, the following items are disclosed in this specification.

(1) A measurement unit that measures blood pressure at a blood pressure measurement site of the measurement subject, a first altitude sensor that detects the altitude of the blood pressure measurement site, and a first displacement that detects displacement in the height direction of the blood pressure measurement site. A correction unit that performs drift correction on the first altitude information detected by the first altitude sensor based on the first displacement information detected by the sensor, the first displacement sensor, and the correction unit An electronic sphygmomanometer, comprising: an altitude difference calculation unit that calculates an altitude difference between the blood pressure measurement unit and the heart of the subject using the first altitude information.
(2) In the electronic sphygmomanometer according to (1), when the first altitude information has a change and the first displacement information has a change, the correction unit performs the processing on the first altitude information. Electronic sphygmomanometer that performs drift correction.
(3) The electronic sphygmomanometer according to (1) or (2), wherein a data table storing height and an average height difference between the blood pressure measurement site and a heart in a predetermined posture is stored. The altitude difference calculation unit further includes a first altitude information acquired in advance in the predetermined posture before measurement by the measurement unit and first altitude information acquired during measurement by the measurement unit. The amount of displacement in the height direction of the blood pressure measurement site is calculated from the above, and the height difference is calculated from the average height difference and the amount of displacement corresponding to the height information of the measurement subject held in the data table. Electronic blood pressure monitor.
(4) The electronic blood pressure monitor according to any one of (1) to (3), wherein the first altitude sensor is an absolute pressure sensor.
(5) The electronic sphygmomanometer according to any one of (1) to (4), wherein the first displacement sensor is an acceleration sensor.
(6) The electronic blood pressure monitor according to (1) or (2), wherein a second altitude sensor that detects an altitude of the heart of the subject and a second that detects a displacement of the heart of the subject. A displacement sensor, and the correction unit performs drift correction on the second altitude information detected by the second altitude sensor based on the second displacement information detected by the second displacement sensor, The calculator is an electronic sphygmomanometer that calculates the altitude difference from the first altitude information and the second altitude information processed by the correction unit.
(7) In the electronic sphygmomanometer according to (6), the correction unit may change the second height information when there is a change in the second height information and there is a change in the second displacement information. Electronic sphygmomanometer that performs drift correction.
(8) The electronic sphygmomanometer according to (6) or (7), wherein the first altitude sensor and the second altitude sensor are absolute pressure sensors.
(9) The electronic blood pressure monitor according to any one of (6) to (8), wherein the first displacement sensor and the second displacement sensor are acceleration sensors.
(10) The electronic sphygmomanometer according to any one of (1) to (9), wherein the head pressure due to the altitude difference of the blood pressure at the blood pressure measurement site measured by the measurement unit is corrected. An electronic sphygmomanometer further comprising a blood pressure calculation unit for calculating the blood pressure of the measurement subject.
(11) In the electronic sphygmomanometer according to (10), the blood pressure calculation unit adds a hydraulic head pressure corresponding to the altitude difference to the blood pressure measured by the measurement unit, and An electronic sphygmomanometer that calculates blood pressure.
(12) The electronic sphygmomanometer according to (10), further including a cuff attached to the blood pressure measurement site, wherein the measurement unit gradually changes the compression pressure of the cuff against the blood pressure measurement site. An adjustment unit; and a detection unit that detects a pulsation feature amount in the blood pressure measurement site in a process of changing the compression pressure of the cuff, and the feature amount detected by the detection unit reaches a predetermined threshold level. The compression pressure of the cuff is determined to be a blood pressure, the blood pressure calculation unit increases or decreases the threshold level according to the altitude difference, and the blood pressure determined by the measurement unit is the blood pressure of the subject Electronic blood pressure monitor.
(13) The electronic blood pressure monitor according to (12), wherein the feature amount is a pulse wave amplitude.
(14) The electronic blood pressure monitor according to (12), wherein the feature amount is a Korotkoff sound.
(15) In the electronic sphygmomanometer according to any one of (1) to (9), a guide unit that guides the blood pressure measurement site to the altitude of the heart of the subject based on the altitude difference. An electronic blood pressure monitor further provided.

1 Electronic Blood Pressure Monitor 2 Cuff 4 Blood Pressure Monitor Body 5 Code 10 Fluid Bag 14 Absolute Pressure Sensor 15 Acceleration Sensor 20 Measurement Unit 21 Display Unit 22 Operation Unit 23 Power Supply Unit 30 CPU
31 First memory 32 Second memory 33 Pressure adjustment unit 34 Timer 35 Display device 36 Power switch 37 Measurement switch 38 Setting switch 39 Record call switch 40 Pressure sensor 41 Oscillation circuit 42 Pump 43 Pump drive circuit 44 Valve 45 Valve drive circuit

Claims (15)

A measurement unit for measuring blood pressure at a blood pressure measurement site of the measurement subject;
A first altitude sensor for detecting the altitude of the blood pressure measurement site;
A first displacement sensor for detecting a displacement in a height direction of the blood pressure measurement site;
A correction unit that performs drift correction on the first height information detected by the first height sensor based on the first displacement information detected by the first displacement sensor;
An altitude difference calculating unit that calculates an altitude difference between the blood pressure measurement site and the heart of the subject using the first altitude information processed by the correcting unit;
Electronic blood pressure monitor. The electronic sphygmomanometer according to claim 1,
The correction unit is an electronic sphygmomanometer that performs drift correction on the first altitude information when the first altitude information has changed and the first displacement information has changed. The electronic sphygmomanometer according to claim 1 or 2,
A storage unit that stores a data table that stores the height and the average height difference between the blood pressure measurement site and the heart in a predetermined posture;
The altitude difference calculation unit calculates the blood pressure measurement site from first altitude information acquired in advance in the predetermined posture and first altitude information acquired at the time of measurement by the measurement unit before starting measurement by the measurement unit. An electronic sphygmomanometer that calculates the height difference from the average height difference and the displacement amount corresponding to the height information of the measurement subject held in the data table. The electronic sphygmomanometer according to any one of claims 1 to 3,
The electronic blood pressure monitor, wherein the first altitude sensor is an absolute pressure sensor. The electronic sphygmomanometer according to any one of claims 1 to 4,
The electronic sphygmomanometer, wherein the first displacement sensor is an acceleration sensor. The electronic sphygmomanometer according to claim 1 or 2,
A second altitude sensor for detecting the altitude of the subject's heart;
A second displacement sensor for detecting a displacement of the heart of the measurement subject;
Further comprising
The correction unit performs drift correction on the second height information detected by the second height sensor based on the second displacement information detected by the second displacement sensor;
The calculator is an electronic sphygmomanometer that calculates the altitude difference from the first altitude information and the second altitude information processed by the correction unit. The electronic sphygmomanometer according to claim 6,
The correction unit is an electronic sphygmomanometer that performs drift correction on the second altitude information when the second altitude information is changed and the second displacement information is changed. The electronic blood pressure monitor according to claim 6 or 7,
The electronic blood pressure monitor in which the first altitude sensor and the second altitude sensor are absolute pressure sensors. The electronic sphygmomanometer according to any one of claims 6 to 8,
The electronic sphygmomanometer, wherein the first displacement sensor and the second displacement sensor are acceleration sensors. The electronic sphygmomanometer according to any one of claims 1 to 9,
An electronic sphygmomanometer, further comprising a blood pressure calculation unit that calculates a blood pressure of the measurement subject by correcting a hydrocephalic pressure caused by the altitude difference in blood pressure at the blood pressure measurement site measured by the measurement unit. The electronic sphygmomanometer according to claim 10,
The blood pressure calculation unit is an electronic sphygmomanometer that calculates a blood pressure of the measurement subject by adding a hydraulic head pressure corresponding to the altitude difference to the blood pressure measured by the measurement unit. The electronic sphygmomanometer according to claim 10,
Further comprising a cuff attached to the blood pressure measurement site,
The measurement unit includes a pressure adjustment unit that gradually changes the compression pressure of the cuff with respect to the blood pressure measurement site, and a detection unit that detects a feature amount of pulsation in the blood pressure measurement site in the process of changing the compression pressure of the cuff. And determining the compression pressure of the cuff when the feature amount detected by the detection unit reaches a predetermined threshold level as a blood pressure,
The blood pressure calculation unit is an electronic sphygmomanometer that increases or decreases the threshold level according to the altitude difference and uses the blood pressure determined by the measurement unit as the blood pressure of the measurement subject. The electronic sphygmomanometer according to claim 12,
The electronic sphygmomanometer, wherein the feature amount is a pulse wave amplitude. The electronic sphygmomanometer according to claim 12,
The electronic sphygmomanometer, wherein the characteristic amount is a Korotkoff sound. The electronic sphygmomanometer according to any one of claims 1 to 9,
An electronic sphygmomanometer, further comprising a guide unit that guides the blood pressure measurement site to the altitude of the measurement subject's heart based on the difference in altitude.

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