JP4013366B2 - Arterial stiffness measuring device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an arterial stiffness measuring device for measuring the stiffness of a living artery.
[0002]
[Prior art]
Measuring arterial stiffness is important in diagnosing living arteriosclerosis. Further, since the stiffness of the artery is closely related to the state of the circulatory organ and the autonomic nerve, the state of the circulatory organ and the autonomic nerve can be diagnosed from the hardness of the artery. In addition, since the blood pressure is difficult to control if the artery is stiff, if the arterial hardness can be known before surgery, the degree of difficulty in blood pressure management during surgery can be known. Further, during the operation, when blood pressure fluctuation occurs, it can be determined whether or not the factor is on the blood vessel side (peripheral side), that is, the factor of fluctuation is the heart side (central side) and the blood vessel side ( The stiffness of the arteries is important medical information, such as whether it is located on the peripheral side.
[0003]
[Problems to be solved by the invention]
However, the arterial hardness represents the degree of arterial vessel wall hardness, and thus it was difficult to easily measure from above the skin.
[0004]
The present invention has been made in the background of the above circumstances, and an object of the present invention is to provide an arterial stiffness measuring device capable of easily measuring the stiffness of an artery from the skin. .
[0005]
[Means for Solving the Problems]
The present inventor has conducted various studies against the background described above, and as a result, the relationship between the blood pressure value of the living body and the pulse pressure obtained from the blood pressure value is, for example, the relationship between the average blood pressure value and the pulse pressure in FIG. As shown, it showed a proportional relationship, and it was found that the slope of the straight line indicating the proportional relationship changes depending on the stiffness of the artery. That is, it has been found that an index representing the stiffness of an artery can be expressed based on a ratio between a pulse pressure and a blood pressure value. The present invention has been made based on such findings.
[0006]
That is, the gist of the present invention is an arterial stiffness measuring device for measuring arterial stiffness in a living body, and (a) a compressing device that compresses the artery of the living body, and (b) the compressing device. A blood pressure value determining means for determining the blood pressure value of the living body based on the compression of the artery by the device; and (c) a pulse pressure determination for determining the pulse pressure of the living body from the blood pressure value determined by the blood pressure value determining means. means and, (d) and pulse pressure determined by the pulse pressure determining means, arterial stiffness index determining means for determining the ratio between the blood pressure values determined by the blood pressure determining means as the arterial stiffness index of the living body Is to include.
[0007]
【The invention's effect】
In this way, the blood pressure value determining means determines the blood pressure value based on the compression of the biological artery by the compression device, and the pulse pressure determining means determines the pulse pressure from the blood pressure value determined by the blood pressure value determining means. In the arterial stiffness index determining means, the arterial stiffness index of the living body is determined based on the ratio between the pulse pressure determined by the pulse pressure determining means and the blood pressure value determined by the blood pressure value determining means. Arterial stiffness can be easily measured from above the skin.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Here, preferably, the compression device is a cuff that is wound around a part of the living body and compresses a part of the living body, and the blood pressure value determining means determines a compression pressure by the cuff in advance. The blood pressure value of the living body is determined by increasing the pressure to a predetermined target compression pressure and then decreasing the pressure at a predetermined speed. In this way, the configuration of the compression device is simplified, and there is an advantage that the arterial stiffness index is determined based on a highly reliable blood pressure value using a cuff.
[0009]
Preferably, the arterial stiffness measuring device further includes an activation unit that activates the blood pressure value determining unit at every preset blood pressure value determining period. In this way, since the blood pressure value determining means is started every predetermined blood pressure value determining cycle by the starting means, the arterial stiffness index is determined in the arterial stiffness index determining means every blood pressure value determining cycle. Is determined. Therefore, there is an advantage that the arterial stiffness index can be obtained periodically.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram illustrating the configuration of an arterial stiffness measuring device to which the present invention is applied.
[0011]
In FIG. 1, a cuff 10 has a rubber bag in a cloth band bag and is wound around, for example, an upper arm 12 of a patient. A pressure sensor 14, an exhaust control valve 16, and an air pump 18 are connected to the cuff 10 via a pipe 20. The exhaust control valve 16 is in a pressure supply state that allows supply of pressure into the cuff 10, a slow exhaust pressure state that gradually exhausts the inside of the cuff 10, and a rapid exhaust pressure state that rapidly exhausts the inside of the cuff 10. It is configured to be switched to three states. When pressure is supplied into the cuff 10 by the exhaust control valve 16, the cuff 10 compresses the brachial artery (not shown) of the upper arm 12, and therefore the cuff 10 functions as a compression device in this embodiment.
[0012]
The pressure sensor 14 detects the pressure in the cuff 10 and supplies a pressure signal SP representing the pressure to the static pressure discrimination circuit 22 and the pulse wave discrimination circuit 24, respectively. Static pressure filter circuit 22 includes a low pass filter, the cuff pressure signal SK via the A / D converter 26 and discriminating the cuff pressure signal SK representative of a steady pressure or cuff pressure P _C is included in the pressure signal SP This is supplied to the electronic control unit 28.
[0013]
The pulse wave discriminating circuit 24 includes a band-pass filter, frequency-discriminates the pulse wave signal SM ₁ that is a vibration component of the pressure signal SP, and the pulse wave signal SM is electronically controlled via an A / D converter 29. 28. The cuff pulse wave represented by the pulse wave signal SM is a pressure vibration wave, that is, a pressure pulse wave, which is generated from a brachial artery (not shown) and transmitted to the cuff 10 in synchronization with the heartbeat of the patient. The pulse wave discrimination circuit 24 functions as a pressure pulse wave detection device.
[0014]
The electronic control unit 28 includes a CPU 30, a ROM 32, a RAM 34, and a so-called microcomputer provided with an I / O port (not shown). The CPU 30 has a storage function of the RAM 34 according to a program stored in the ROM 32 in advance. By executing the signal processing while using it, the drive signal is output from the I / O port to control the exhaust control valve 16 and the air pump 18 and the display content of the display 36 is controlled.
[0015]
Start cycle setter 38 is operated to set the blood pressure measurement activation period T _B to start the blood pressure measurement using the cuff 10. The activation switch 40 supplies a signal to the electronic control device 28 that instructs manual activation of blood pressure measurement using the cuff 10.
[0016]
FIG. 2 is a functional block diagram for explaining a main part of the control function of the electronic control device 28 in the arterial stiffness measuring device. In FIG. 2, a blood pressure measuring means 50 functioning as a blood pressure value determining means applies a compression pressure of the cuff 10 wound around the upper arm of the living body by the cuff pressure control means 52 to a predetermined target pressure value P _CM (for example, about 180 mmHg). It is well known based on the change in the amplitude of the pulse wave represented by the pulse wave signal SM that is sequentially sampled during the slow pressure reduction period in which the pressure is gradually increased to about 3 mmHg / sec. oscillometric method systolic blood BP _SYS using a mean blood pressure value BP _mEAN, and the like to determine the diastolic blood pressure value BP _DIA, the determined systolic blood pressure BP _SYS, the mean blood pressure value BP _mEAN, and a diastolic blood pressure BP _DIA or the like is displayed on the display 36.
[0017]
The pulse pressure determining unit 54 determines the pulse pressure PM from the blood pressure value BP determined by the blood pressure measuring unit 50. That is, the difference between the maximum blood pressure value BP _SYS and the minimum blood pressure value BP _DIA determined by the blood pressure measurement unit 50 is calculated. Since the pulse pressure PM is based on the pressure pulse wave generated from the brachial artery (not shown) and transmitted to the cuff 10, it mainly represents the pulse pressure of the brachial artery (not shown).
[0018]
Based on the ratio between the pulse pressure PM determined by the pulse pressure determination means 54 and the blood pressure value BP measured by the blood pressure measurement means 50, the arterial stiffness index determination means 56 The arterial stiffness index _Ia is determined. For example, the pulse pressure PM determined by the pulse pressure determining means 54 and the blood pressure value BP measured by the blood pressure measuring means 50 (any one of the maximum blood pressure value BP _SYS , the average blood pressure value BP _MEAN , and the minimum blood pressure value BP _DIA ). ) as the ratio between calculated as arterial stiffness index I _a. As shown in FIG. 3, the cuff pulse wave is a synthesized wave in which a first pulse wave that is a traveling wave and a second pulse wave that is a reflected wave are synthesized. When the blood vessel becomes hard, the blood pressure regulation function due to the elasticity of the blood vessel becomes impossible, so the second pulse wave (reflected wave) increases, resulting in an increase in blood pressure. This increase in blood pressure has a large effect on the systole when the amount of blood delivered from the heart increases, and has little effect on the diastole. Therefore, when the blood vessel becomes hard, the pulse pressure increases. Therefore, the arterial stiffness index I _a as determined by the arterial stiffness index determining means 56, as shown in FIG. 6, even blood pressure BP is the same, the larger arteries is hard. That is, when the artery becomes hard due to arteriosclerosis, or when vasoconstriction occurs due to the action of autonomic nerves or drugs, the arterial stiffness index _Ia increases.
[0019]
Arterial stiffness index display means 58, the arterial stiffness index I _a, which is determined by the arterial stiffness index determining means 56, to be displayed on the display 36 that the measured blood pressure values BP has been displayed by the blood pressure measuring means 50 . Activation means 60, the activation period setter 38 blood pressure measurement period T each _B set by, and by a signal supplied from the activation switch 40 to activate the blood pressure measurement by the blood pressure measuring means 50.
[0020]
FIG. 4 is a flowchart for explaining a main part of the control operation in the electronic control device 28 of the arterial stiffness measuring device. In FIG. 4, first, in S1 (hereinafter step is omitted), the content of the timer t is cleared.
[0021]
Next, S2 to S3 corresponding to the activation means 60 are executed. First, in S2, it is determined whether or not a signal for instructing blood pressure measurement activation is manually input, that is, whether or not the activation switch 40 is pressed. If the determination in S2 is no, the subsequent S3, whether the contents of the timer t exceeds the blood pressure measurement activation period T _B which is set by the activation cycle setter 38 is determined. If the determination in S3 is denied, by the after S2 is repeatedly executed, or activation switch 40 is pressed, the contents of the timer t is made to wait until after the blood pressure measurement activation period T _B.
[0022]
When the determination of S2 or S3 is affirmed, S4 to S5 corresponding to the cuff pressure control means 52 are executed. That is, in S4, after the exhaust control valve 16 is switched to the pressure supply state and the inside of the cuff 10 in which the air pump 18 is driven is increased to a preset target compression pressure P _CM (for example, a pressure of about 180 mmHg), the air is The pump 18 is stopped. In subsequent S5, the exhaust control valve 16 is switched to the slow exhaust state, whereby the pressure in the cuff 10 is lowered at a moderate speed of about 3 mmHg / sec.
[0023]
Subsequently, S6 to S9 corresponding to the blood pressure measuring means 50 are executed. First, by executing S6, it is determined whether the pulse wave signal SM is read and one pulse wave is detected. If this determination is negative, the above S6 is repeatedly executed, but if the determination is affirmative, the blood pressure value determination routine of S7 is executed. In this blood-pressure determining routine, the cuff pressure P _C the slow based on the sequentially detected amplitude variation of the pulse wave step-down process of the well-known oscillometric method systolic blood BP _SYS in accordance blood pressure determining algorithm The minimum blood pressure value BP _DIA and the average blood pressure value BP _MEAN are determined. In subsequent S8, it is determined whether or not the blood pressure measurement has been completed. If the blood pressure measurement has not been completed, S6 to S8 are repeatedly executed.
[0024]
When the blood pressure measurement is completed and the determination in S8 is affirmed, S9 is executed, so that the maximum blood pressure value BP _SYS , the average blood pressure value BP _MEAN , and the minimum blood pressure value BP _DIA determined in S7 are obtained. Are stored in a predetermined storage area in the RAM 34 and displayed on the display 36. In subsequent S10, the exhaust control valve 16 is switched to the rapid exhaust pressure state, and the pressure in the cuff 10 is released.
[0025]
In S11 corresponding to the subsequent pulse pressure determining means 54, the difference between the systolic blood pressure value BP _SYS and the systolic blood pressure value BP _DIA measured in S7, that is, the pulse pressure PM is calculated. In S12 corresponding to the following arterial stiffness index determining means 56, the arterial stiffness index _Ia is calculated by dividing the pulse pressure PM calculated in S11 above by the average blood pressure value BP _MEAN determined in S7. , in S13 corresponding to the subsequent arterial stiffness index display means 58, the arterial stiffness index I _a calculated at S12 above is displayed on the display 36 the blood pressure value BP is displayed in the S9. In S13, when the arterial stiffness index _Ia is displayed on the display unit 36 together with the blood pressure value BP periodically, that is, when the blood pressure value BP is an abnormal value, the cause of the abnormality is on the blood vessel side. It can be determined whether or not there is, and can be used as a guide for treatment.
[0026]
As described above, according to the present embodiment, the blood pressure measurement unit 50 (S6 to S9) determines the blood pressure value BP based on the compression of the artery of the living body by the cuff 10, and the pulse pressure determination unit 54 (S11) The pulse pressure PM is determined from the blood pressure value BP measured by the blood pressure measuring means 50 (S6 to S9), and the pulse determined by the pulse pressure determining means 54 (S11) is determined by the arterial stiffness index determining means 56 (S12). the pressure PM, since the ratio of mean blood pressure BP _mEAN measured by the blood pressure measuring means 50 (S6 to S9) is determined as arterial stiffness index I _a, be easily measured arterial stiffness over the skin Can do.
[0027]
Further, according to the present embodiment, the cuff 10 wound around the upper arm portion 12 and compresses the upper arm portion 12 functions as a compression device, and the blood pressure measuring means 50 (S6 to S9) is compressed by the cuff 10 after boosting to the target compression pressure P _CM which is predetermined pressure, since what determines blood pressure values BP by stepped down by a predetermined rate, the configuration of the compression apparatus is simplified, the cuff 10 There is an advantage that the arterial stiffness index _Ia is determined based on the highly reliable blood pressure value BP used.
[0028]
Further, according to this embodiment, the activation means 60 (S2 to S3), since the blood pressure measuring means 50 (S6 to S9) is to activate a preset blood pressure measurement start each period T _B, the blood pressure measurement each activation period T _B, since the arterial stiffness index I _a is determined in the arterial stiffness index determining means 56 (S12), periodically the advantage of arterial stiffness index I _a is obtained.
[0029]
As mentioned above, although the Example of this invention was described in detail based on drawing, this invention is applied also in another aspect.
[0030]
For example, the blood pressure measurement means 50 (S6 to S9) of the above-described embodiment is configured to measure the blood pressure value BP by a so-called oscillometric method, but based on the cuff pressure at the time of occurrence and disappearance of Korotkoff sound. The blood pressure may be measured by the so-called K sound method for measuring the blood pressure value BP.
[0031]
In the above-described embodiment, the cuff 10 wound around the upper arm portion 12 functions as a compression device, and the blood pressure measurement means 50 is a living body based on the cuff pulse wave detected in the changing process of the compression pressure of the cuff 10. The blood pressure value BP was measured, but as a compression device, it was attached to the wrist or foot to detect the pressure pulse wave of the radial artery or the dorsal artery, and the radial artery or the dorsal artery with a predetermined pressure. A pressure pulse wave detection device that compresses the blood pressure, and the blood pressure value determining means sequentially determines the maximum blood pressure value and the minimum blood pressure value of the living body based on the pressure pulse wave sequentially detected by the pressure pulse wave detection device It may be.
[0032]
Further, the arterial stiffness index determining means 56 in the illustrated embodiments (S12), but the ratio between the pulse pressure PM and the blood pressure values BP (PM / BP) has been considered as arterial stiffness index I _a, the ratio ( PM / BP) and on the basis of a previously obtained relationship between arterial stiffness index I _a (wherein, the graph), be those arterial stiffness index I _a is determined from the ratio (PM / BP) May be. FIG. 5 is a diagram showing an example of the relationship obtained in advance, showing the relationship between the ratio (PM / BP _MEAN ) between the pulse pressure PM and the average blood pressure value BP _MEAN and the arterial stiffness index I _a. ing. Further, the arterial stiffness index _Ia may be calculated based on a ratio (BP / PM) of the blood pressure value BP to the pulse pressure PM or a relationship obtained in advance from the ratio (BP / PM). Good.
[0033]
Further, in the illustrated embodiment, although the blood pressure measurement activation period T _B was composed as set by the activation cycle setter 38, or may be set to a predetermined constant value.
[0034]
The present invention can be modified in various other ways without departing from the spirit of the present invention.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of an arterial stiffness measuring apparatus according to an embodiment of the present invention.
2 is a functional block diagram illustrating a main part of a control function of the electronic control device in the embodiment of FIG. 1; FIG.
FIG. 3 is a diagram for explaining a cuff pulse wave transmitted to the cuff of the embodiment of FIG. 1;
4 is a flowchart illustrating a main part of a control operation of the electronic control device in the embodiment of FIG. 1; FIG.
FIG. 5 is a diagram showing an example of a relationship between _a ratio (PM / BP _MEAN ) and an arterial stiffness index Ia.
[6] the relationship between the mean blood pressure and pulse pressure is a diagram illustrating the changing arterial stiffness index I _a.
[Explanation of symbols]
10: Cuff (compression device)
50: Blood pressure measuring means (blood pressure value determining means)
54: Pulse pressure determining means 56: Arterial stiffness index determining means 60: Starting means

Claims (1)

An arterial stiffness measuring device for measuring arterial stiffness in a living body,
A compression device for compressing the living artery;
A blood pressure value determining means for determining the blood pressure value of the living body based on the compression of the artery by the compression device;
Pulse pressure determining means for determining the pulse pressure of the living body from the blood pressure value determined by the blood pressure value determining means;
A pulse pressure which is determined by該脈pressure determining means, and arterial stiffness index determining means for determining the ratio between the blood pressure values determined by the blood pressure determining means as the arterial stiffness index of the body, in that it comprises A characteristic arterial stiffness measuring device.

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