JP2016019697A - Central blood pressure measurement device and central blood pressure measurement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a central blood pressure measurement device capable of accurately measuring central blood pressure.SOLUTION: The central blood pressure is estimated by using, a peripheral arterial pulse wave P1 and an aorta pulse wave P2. First, a tidal wave (main peak) P2X of the aorta pulse wave P2 is detected. Then, an amplitude (corresponding to blood pressure) of the peripheral arterial pulse wave P1 at a time point t1 when the tidal wave (main peak) P2X is detected, is estimated as the central blood pressure. Thereby, even when the tidal wave P1X of the peripheral arterial pulse wave P1 is not expressed as a clear change point, the central blood pressure can be measured accurately.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a central blood pressure measuring device and a central blood pressure measuring method for measuring central blood pressure, which is the blood pressure of an aorta.

  Since the central blood pressure is a pressure directly applied to major organs such as the heart, the measured value is considered to be an index value for arteriosclerosis and cardiovascular disease.

  One method for measuring central blood pressure is an invasive measurement method in which a catheter is inserted into the aorta. However, this method has a problem that the burden on the body of the subject increases.

  As another method for measuring the central blood pressure, there is a method for estimating the central blood pressure based on a volume pulse wave or a pressure pulse wave (hereinafter simply referred to as a pulse wave) of a peripheral artery measured non-invasively. This method measures the blood pressure pulse wave of the upper arm using, for example, a cuff, detects a tidal wave that appears following the percussion wave of the blood pressure pulse wave of the upper arm, and detects the level of the tidal wave. Is the central blood pressure (maximum blood pressure of the central blood pressure). A method for estimating the central blood pressure in this way is disclosed, for example, on the Internet <URL: http://www.colin.omron.co.jp/products/feature/127.html>.

  By the way, in the method of measuring the pulse wave of the peripheral artery non-invasively as described above, detecting the tidal wave of the pulse wave, and setting the level of this tidal wave as the central blood pressure, the detection accuracy of the tidal wave is the center. This greatly affects blood pressure measurement accuracy (which may be called estimation accuracy).

  In general, the tidal wave in the peripheral arterial pulse wave is an inflection point and can be detected by the second derivative or the fourth derivative, but corresponds to the central blood pressure in the measured peripheral arterial pulse waveform. Tidal waves (inflection points) do not always appear clearly. In that case, there is a problem that the estimation accuracy of the central blood pressure is lowered or the estimation becomes difficult.

  The present invention has been made in consideration of the above points, and provides a central blood pressure measuring apparatus and a central blood pressure measuring method capable of measuring central blood pressure with high accuracy.

One aspect of the central blood pressure measurement device of the present invention is:
A central blood pressure measuring device that measures central blood pressure, which is the blood pressure of the aorta,
A peripheral arterial pulse wave / blood pressure measuring unit for measuring the peripheral arterial pulse wave and blood pressure of the subject;
An aortic pulse wave measuring unit for measuring the aortic pulse wave of the subject by measuring a change in electrical impedance of the aorta;
A central blood pressure estimating unit that estimates the central blood pressure using the peripheral arterial pulse wave measured by the peripheral arterial pulse wave / blood pressure measuring unit and the aortic pulse wave measured by the aortic pulse wave measuring unit;
It comprises.

  According to the present invention, the central blood pressure is estimated with high accuracy by using the peripheral arterial pulse wave measured by the peripheral arterial pulse wave measuring unit and the aortic pulse wave measured by the aortic pulse wave measuring unit. Can be measured.

Diagram for explaining the principle of the embodiment A diagram showing the peripheral arterial pulse wave (FIG. 2A) and the aortic pulse wave (FIG. 2B) along the time axis. Diagram showing the concept of central blood pressure estimation using the shapes of peripheral artery pulse and aortic pulse wave The block diagram which shows the whole structure of the biological information measuring device which concerns on embodiment The top view which looked at the 1st cuff and the 2nd cuff from the inner surface (mounting surface) direction A-A 'sectional view of FIG. Diagram for explaining electrical connection and operation of each electrode

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

<Principle>
First, before describing the configuration of the embodiment, the principle of this embodiment will be described with reference to FIGS. 1, 2, and 3.

  As shown in FIG. 1, in this embodiment, the peripheral arterial pulse wave P1 of the peripheral artery 11 of the subject 10 is measured non-invasively, and the aortic pulse wave P2 of the aorta 12 of the subject 10 is non-invasively measured. Measure invasively.

  Here, the peripheral arterial pulse wave P1 is measured together with the blood pressure by the cuff. The amplitude of the peripheral arterial pulse wave P1 represents blood pressure. The aortic pulse wave P2 can be measured by measuring a change in impedance of the aorta, as will be described later.

  The part for measuring the aortic pulse wave P2 may be the aortic arch that is the starting part of the aorta, or the thoracic aorta or the abdominal aorta.

  Next, a feature point is detected in the aortic pulse wave P2, and the blood pressure level of the peripheral arterial pulse wave P1 at the position corresponding to the feature point is estimated as the central blood pressure. Here, the feature point to be detected is a tidal wave in the aortic pulse wave P2. Usually, since the tidal wave in the aortic pulse wave P2 becomes the main peak of the aortic pulse wave P2, in this embodiment, the main peak of the aortic pulse wave P2 is detected.

  FIG. 2 shows the peripheral arterial pulse wave P1 (FIG. 2A) and the aortic pulse wave P2 (FIG. 2B) along the time axis. The tidal wave P1X of the peripheral artery pulse wave P1 and the tidal wave P2X of the aortic pulse wave P2 appear at the same time t1. As can be seen from the figure, the tidal wave P2X of the aortic pulse wave P2 appears more clearly than the tidal wave P1X of the peripheral arterial pulse wave P1. That is, detection is easy. In the present invention, using this point, first, a tidal wave (actually the main peak) P2X of the aortic pulse wave P2 is detected, and the amplitude (that is, equivalent to blood pressure) of the peripheral arterial pulse wave P1 at the time t1 is detected. By looking, the central blood pressure is obtained.

  In another aspect, the present invention corresponds to the main peak of the aortic pulse wave P2 in the peripheral arterial pulse wave P1 based on the measured shapes of the peripheral arterial pulse wave P1 and the aortic pulse wave P2. It can be said that the central blood pressure is estimated based on the blood pressure level of the peripheral arterial pulse wave P1 at the position corresponding to the detected main peak.

  FIG. 3 shows the concept of central blood pressure estimation using the shapes of the peripheral arterial pulse wave P1 and the aortic pulse wave P2 according to the present embodiment. FIG. 3 shows that the longitudinal scale of the aortic pulse wave P2 is adjusted so that the main peak P2X intersects the peripheral arterial pulse wave P1 with the time axis of the peripheral arterial pulse wave P1 and the aortic pulse wave P2 aligned. Is. That is, the intersection point on the peripheral artery pulse wave P1 is the point P1X.

  FIG. 3 shows an example where the blood pressure of the peripheral artery represented by the amplitude of the peripheral artery pulse wave P1 is a minimum blood pressure of 80 mmHg and a maximum blood pressure of 120 mmHg. In the example of FIG. 3, the blood pressure at the point P1X on the peripheral artery pulse wave P1 is 105 mmHg. Therefore, the central blood pressure is estimated to be 105 mmHg.

  As described above, in the present embodiment, the tidal wave P1X on the peripheral arterial pulse wave P1 that has been obtained by the second derivative or the fourth derivative is obtained by using the aortic pulse wave P2. Even when P1X does not appear as a clear change point, the tidal wave P1X corresponding to the tidal wave (main peak) P2X of the aortic pulse wave P2 can be detected with high accuracy, and as a result, the central blood pressure can be detected with high accuracy. Can be measured.

<Configuration>
FIG. 4 is a schematic diagram showing the overall configuration of a biological information measuring device equipped with the central blood pressure measuring device of the present invention.

  The biological information measuring apparatus 100 includes a first cuff 110 and a second cuff 120. A first electrode 111 and a second electrode 121 are provided on each of the first cuff 110 and the second cuff 120. The first cuff 110 is attached to the subject's upper limb, and the second cuff 120 is attached to the subject's lower limb. In the present embodiment, the first cuff 110 is attached to the left upper arm, and the second cuff 120 is attached to the right ankle.

  Furthermore, the biological information measuring apparatus 100 includes a blood pressure pulse wave measurement unit 130, an impedance pulse wave measurement unit 140, an electrocardiogram measurement unit 150, a control / calculation unit 160, a storage unit 171, an input unit 172, a display unit 173, an audio unit 174, and the like. A printing unit 175 is included.

  The control / calculation unit 160 includes a CPU (Central Processing Unit), a memory, and the like, and controls the operation of each unit in the apparatus by executing a biological information measurement program stored in the memory by the CPU. Perform operations necessary to obtain information.

  The storage unit 171 is a storage device such as a hard disk, and stores measurement results and the like under the control of the control / calculation unit 160. The input unit 172 includes an input device such as a keyboard, a mouse, or a button, and outputs an operation signal corresponding to a user operation to the control / calculation unit 160. The control / calculation unit 160 performs control and calculation according to the operation signal. The display unit 173 is a display device such as a liquid crystal display, and displays a setting screen, operation guidance, a biological information test result report, or the like under the control of the control / calculation unit 160. Note that the display unit 173 may be configured by a touch panel and may have an input function in addition to the display function. The voice unit 174 is a speaker device, and outputs operation guidance or an alarm sound according to the control of the control / calculation unit 160. The printing unit 175 is a printer device such as a thermal printer, and prints a biological information test result report or the like under the control of the control / arithmetic processing unit 160.

  The blood pressure pulse wave measurement unit 130 functions as a peripheral artery pulse wave / blood pressure measurement unit that measures the pulse wave and blood pressure of the peripheral artery of the subject. The blood pressure pulse wave measurement unit 130 includes a pump and an exhaust valve for supplying and exhausting the cuffs 110 and 120, a pressure sensor for detecting the pressure of the cuffs 110 and 120, and a predetermined signal such as amplification for a detection signal from the pressure sensor. It comprises a signal processing circuit that performs the signal processing. The blood pressure pulse wave measurement unit 130 increases the internal pressure of the cuffs 110 and 120 (hereinafter, the internal pressure of the cuff is referred to as “cuff pressure”) by introducing air into the air bags of the cuffs 110 and 120 through the hose, The cuff pressure of the cuffs 110 and 120 is reduced by discharging air from the air bag. The target value of the cuff pressure after pressurization is different for pulse wave measurement and blood pressure measurement, and can be set individually.

  In the case of the present embodiment, measurement of the peripheral arterial pulse wave and measurement of the impedance pulse wave (aortic pulse wave) are performed simultaneously.

  The peripheral arterial pulse wave can be measured using both the first cuff 110 and the second cuff 120, or either the first cuff 110 or the second cuff 120. In the case of the present embodiment, the peripheral arterial pulse wave and blood pressure are measured using the first cuff 110, that is, the upper arm cuff.

  When measuring a peripheral artery pulse wave and an impedance pulse wave (aortic pulse wave), the blood pressure pulse wave measurement unit 130 first pressurizes the cuff pressures of the cuffs 110 and 120 until a predetermined value is reached. The reason why the cuff that does not measure the peripheral arterial pulse wave is pressurized is to make the electrode provided on the cuff as close as possible to the subject for the measurement of the impedance pulse wave. In the present embodiment, the cuff pressure when measuring the peripheral artery pulse wave and the impedance pulse wave (aortic pulse wave) is controlled to 30 to 40 mmHg.

  The blood pressure pulse wave measurement unit 130 detects a change in the cuff pressure of the cuff 120 after pressurization with a pressure sensor as a peripheral arterial pulse wave signal, and outputs the detected peripheral arterial pulse wave signal to the control / calculation unit 160.

  On the other hand, in the case of blood pressure measurement, the blood pressure pulse wave measurement unit 130 detects the cuff pressure vibration of the cuff 110 and / or 120 with the pressure sensor during decompression, and uses the cuff pressure at the time when the amplitude starts to increase as the systolic blood pressure. While detecting, the cuff pressure with the most remarkable vibration reduction is detected as the diastolic blood pressure. Then, the blood pressure pulse wave measurement unit 130 outputs blood pressure signals respectively indicating the detected systolic blood pressure and diastolic blood pressure to the control / calculation unit 160.

  The electrocardiogram measurement unit 150 is connected to electrodes 111 and 121 provided in the cuffs 110 and 120. The electrocardiogram measurement unit 150 includes a signal processing circuit that performs predetermined signal processing such as amplification on the detection signals detected by the electrodes 111 and 121. The electrocardiogram measurement unit 150 outputs the detection signal after signal processing to the control / calculation unit 160 as an electrocardiogram signal.

  The impedance pulse wave measurement unit 140 was measured with a high-frequency constant current power source that supplies a high-frequency constant current to the electrodes 111 and 121, and a voltmeter that measures the voltage between the electrodes 111 and 121 when the high-frequency constant current was supplied. An impedance pulse wave forming unit that obtains an impedance pulse wave based on the voltage.

  As already known, the impedance pulse wave measurement principle is based on the fact that the impedance in the path through the heart 200 changes mainly depending on the blood flow volume of the aorta, that is, the blood volume. Specifically, the impedance decreases as the blood volume increases. Here, before the aortic valve is opened, there is almost no aortic blood flow and the impedance increases. On the other hand, after opening the aortic valve, a pulsatile flow of the aorta occurs, the blood flow increases and the impedance decreases. The impedance pulse wave is obtained by measuring the impedance that varies with the pulsatile flow from such an aortic valve.

  Here, the frequency of the high-frequency constant current generally used for measuring the impedance pulse wave is around 50 kHz, while the electrocardiogram component is at most about 100 Hz, and the frequency band is greatly separated. Therefore, even if they are mixed, the component of the impedance pulse wave and the component of the electrocardiogram can be easily separated by a technique such as filtering, so the measurement by the impedance pulse wave measurement unit 140 and the measurement by the electrocardiogram measurement unit 150 are performed simultaneously. be able to.

  As described above, the control / calculation unit 160 uses the peripheral arterial pulse wave P1 obtained by the blood pressure pulse wave measurement unit 130 and the aortic pulse wave P2 obtained by the impedance pulse wave measurement unit 140 to perform central blood pressure. Is estimated.

  FIG. 5 is a plan view of the first cuff 110 and the second cuff 120 of the present embodiment as viewed from the inner surface (mounting surface) direction, and FIG. 6 is a cross-sectional view showing the AA ′ cross section of FIG. is there.

  The first cuff 110 has an arm band 112 wound around the arm, an air bag 113 provided in the arm band 112, and an electrode 111 fixedly provided on the surface of the arm band 112. The electrode 111 includes two electrodes 111 a and 111 b that are provided at a predetermined interval in the width direction of the first cuff 110.

  Each electrode 111a, 111b is provided so as to extend in the longitudinal direction of the first cuff 110. The electrodes 111a and 111b are made of a metal foil such as copper. Note that it is preferable to form the electrodes 111a and 111b with a conductive cloth because the touch is improved. The conductive cloth may be made from highly conductive fibers.

  A hose 114 connected to the blood pressure pulse wave measurement unit 130 is attached to the air bag 113. In addition, a lead wire (not shown) is attached to each of the electrodes 111a and 111b. Both lead wires attached to the respective electrodes 111a and 111b are connected to the impedance pulse wave measuring unit 140, and any one of the lead wires attached to the respective electrodes 111a and 111b is connected to the electrocardiogram measuring unit 150. It is connected.

  Similarly, the second cuff 120 includes a foot band 122 wound around the ankle, an air bag 123 provided in the foot band 122, and an electrode 121 fixed to the surface of the foot band 122. The electrode 121 includes two electrodes 121 a and 121 b provided at a predetermined interval in the width direction of the second cuff 120. Each of the electrodes 121 a and 121 b is provided so as to extend in the longitudinal direction of the second cuff 120. The electrodes 121a and 121b are made of a metal foil such as copper. Note that it is preferable to form the electrodes 121a and 121b with a conductive cloth because the touch is improved. A hose 124 connected to the blood pressure pulse wave measurement unit 130 is attached to the air bag 123. Moreover, a lead wire (not shown) is attached to each electrode 121a, 121b. Both lead wires attached to the electrodes 121a and 121b are both connected to the impedance pulse wave measurement unit 140, and any one of the lead wires attached to the electrodes 121a and 121b is connected to the electrocardiogram measurement unit 150. It is connected.

  FIG. 7 is a diagram for explaining the electrical connection and operation of the electrodes 111a, 111b, 121a, and 121b.

  The high frequency constant current power source 141 and the voltmeter 142 are provided in the impedance pulse wave calculation unit 140. The electrodes 111b and 121b are connected to the high-frequency constant current power source 141, whereby a high-frequency constant current is supplied between the electrodes 111b and 121b. The voltage between the electrodes 111a and 121a arranged on the inner side (closer to the heart 200) than the electrodes 111b and 121b is measured by the voltmeter 142, and the impedance pulse wave measuring unit 140 is based on the measured voltage. (That is, impedance in a path through the heart 200) is measured. In addition, since the method of calculating | requiring an impedance pulse wave is a known technique, description here is abbreviate | omitted. For example, the impedance pulse wave can be detected by extracting a component having a heartbeat-synchronous component as a fundamental wave from the measured impedance by filtering.

  Thus, when a high frequency constant current is supplied to the electrodes 111b and 121b, a current flows between the electrodes 111b and 121b. Since the current value flowing through the electrodes 111b and 121b is a constant current, the voltage value varies depending on the blood ejected from the heart as described above. The impedance pulse wave measurement unit 140 detects this change in voltage value with a voltmeter, and obtains an impedance pulse wave (aortic pulse wave P2) based on the change.

  As described above, according to the present embodiment, the blood pressure pulse wave measurement unit 130 as the peripheral artery pulse wave / blood pressure measurement unit for measuring the pulse wave and blood pressure of the peripheral artery, and changes in the electrical impedance of the aorta are measured. Thus, the impedance pulse wave measurement unit 140 as an aortic pulse wave measurement unit that measures the pulse wave of the aorta of the subject, the peripheral artery pulse wave P1 measured by the blood pressure pulse wave measurement unit 130, and the impedance pulse wave measurement unit By providing the control / calculation unit 160 as a central blood pressure estimation unit that estimates the central blood pressure using the aortic pulse wave P2 measured by 140, the tidal wave P1X is clear on the peripheral arterial pulse wave P1. Even if it does not appear as a change point, the tidal wave P1X can be detected with high accuracy from the tidal wave (main peak) P2X of the aortic pulse wave P2. As a result, it is possible to measure the aortic pressure with high accuracy.

  In the above-described embodiment, the case where the impedance pulse wave (aortic pulse wave P2) is measured by providing an electrode on the cuff has been described. However, the measurement method of the impedance pulse wave (aortic pulse wave P2) is described here. The point is not limited to the above, and it is only necessary to measure the pulse wave of the aorta by measuring a change in electrical impedance of the aorta.

  Moreover, although the case where the peripheral artery pulse wave and blood pressure were measured using the cuff was described in the above-described embodiment, the peripheral artery pulse wave may be measured using something other than the cuff. The peripheral arterial pulse wave can be measured by, for example, a tonometry method, a photoelectric pulse wave method, a strain sensor method, an ultrasonic method, or the like.

  The above-described embodiments are merely examples of implementation in carrying out the present invention, and the technical scope of the present invention should not be construed as being limited thereto. That is, the present invention can be implemented in various forms without departing from the gist or the main features thereof.

  The present invention can compare the peripheral arterial pulse wave and the aortic pulse wave measured for each beat for each beat, and obtain the central blood pressure for each beat. Further, the present invention can be used for a 24-hour blood pressure monitor or a blood pressure monitor for a biological information monitor. When used for a 24-hour sphygmomanometer, a state in which the central blood pressure is high can be monitored for each time zone by monitoring for 24 hours. On the other hand, when used for a biological information monitor, for example, it is possible to detect that the central blood pressure is high and present an alarm of a high central blood pressure value.

  As the peripheral arterial pulse wave, it is desirable to use a volume pulse wave of a cuff pressurized with a pressure larger than the systole or pressurized with a pressure smaller than the diastole. In particular, the volume pulse wave of the cuff pressurized with a pressure greater than the systole is a pulse wave waveform with a small amplitude but a clear shape (in focus), so the central blood pressure is estimated by shape matching. It is suitable for use in the apparatus and method of this embodiment. In this way, the central blood pressure can be estimated with higher accuracy by using the volume pulse wave of the cuff pressurized with a pressure larger than the systole.

  The present invention can be applied to an apparatus for measuring central blood pressure, which is blood pressure of an aorta.

DESCRIPTION OF SYMBOLS 10 Subject 11 Peripheral artery 12 Aorta 100 Biological information measuring device 110, 120 Cuff 111, 121 Electrode 130 Blood pressure pulse wave measurement unit 140 Impedance pulse wave measurement unit 160 Control / calculation unit P1 Peripheral artery pulse wave P2 Aortic pulse wave P1X, P2X Tidal Wave

Claims (5)

A central blood pressure measuring device that measures central blood pressure, which is the blood pressure of the aorta,
A peripheral arterial pulse wave / blood pressure measuring unit for measuring the peripheral arterial pulse wave and blood pressure of the subject;
An aortic pulse wave measuring unit for measuring the aortic pulse wave of the subject by measuring a change in electrical impedance of the aorta;
A central blood pressure estimating unit that estimates the central blood pressure using the peripheral arterial pulse wave measured by the peripheral arterial pulse wave / blood pressure measuring unit and the aortic pulse wave measured by the aortic pulse wave measuring unit;
A central blood pressure measuring device. The central blood pressure estimation unit detects a feature point in the aortic pulse wave, and estimates a central blood pressure based on a blood pressure level of the peripheral artery pulse wave at a position corresponding to the feature point;
The central blood pressure measurement measure according to claim 1. The characteristic point is a tidal wave in the aortic pulse wave.
The central blood pressure measuring device according to claim 2. The feature point is a main peak in the aortic pulse wave.
The central blood pressure measuring device according to claim 2. A central blood pressure measurement method for measuring central blood pressure, which is the blood pressure of an aorta,
Peripheral artery pulse wave and blood pressure measurement step for measuring the pulse wave and blood pressure of the peripheral artery of the subject,
An aortic pulse wave measuring step for measuring a pulse wave of the aorta of the subject by measuring a change in electrical impedance of the aorta;
A central blood pressure estimating step for estimating the central blood pressure using the peripheral arterial pulse wave measured in the peripheral arterial pulse wave / blood pressure measuring step and the aortic pulse wave measured in the aortic pulse wave measuring step;
A central blood pressure measurement method including:

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