JPH0370489B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a device for measuring the opening propagation velocity when a blocked blood vessel opens due to external pressure, and is mainly used for measuring the degree of arteriosclerosis. It is something that can be done.

(Problems with conventional technology) In order to measure the degree of arteriosclerosis, conventional methods such as
As in the technology described in Japanese Patent Laid-Open No. 57-6930 or Japanese Patent Application Laid-Open No. 57-134141, arterial It is common to measure the degree of arteriosclerosis by measuring the pulse wave propagation velocity from the time difference between pulse wave waveforms measured between two points.

However, when recording an actual pulse wave, two pressure sensors are held in place with fingers and pressed against pulsating areas of arteries that are far apart, such as the carotid artery and femoral artery. Due to the fact that the contact position of the pressure sensor is shifted and the waveform is easily distorted due to the strength of the pressure, it is difficult to accurately record the waveform unless it is done by an experienced person.

In addition, a device that measures blood wave changes while pressing a plurality of piezoelectric elements in tandem against the pulsating part of an artery and diagnoses disorders in various functions of the human body based on the measurement results is particularly well known. It is described in JP-A-52-30086 and JP-A-52-7782.

The technology described in Japanese Patent Application Laid-Open No. 52-30086 is 3
Pulse diagnosis is performed by grasping the pulse at Sun, Kan, and Shaku using piezoelectric elements, and the pulse waves at three locations are recorded on a graph and diagnosis is made based on the ratio of the pulse rate to the respiratory rate at that time or the waveform. It is a pulse diagnosis device that does not claim to measure the opening propagation velocity of occluded blood vessels, much less that it detects rapid pressure changes accompanying the opening of blood vessels using multiple piezoelectric elements arranged in tandem and uses the time difference between them. It does not measure opening speed.

The technique described in JP-A-52-7782 obtains composite wave change signals such as changes in blood pulsation and changes in elasticity of blood vessel walls at multiple locations, separates them from external pressing force, and records them over time. Alternatively, pulse changes are recorded over time while the pressing force is sequentially increased to obtain information for determining the pulse diagnosis, and pulse changes are recorded over time at multiple different locations.
This device is not intended to measure the time difference between opening a blood vessel after it is occluded by pressure, and is not suitable as a device for diagnosing the degree of arteriosclerosis.

However, since the propagation velocity of the pulse wave, which is the basis of measurement in the above-mentioned conventional techniques, is as fast as 7 to 10 msec,
In order to measure with sufficient accuracy, the two measurement points must be approximately 50cm apart, but even when they are 50cm apart, the propagation time is 50 to 70msec.
Therefore, since such a slight time difference of several tens of milliseconds is measured from multiple pulse waves, the phase difference between the waveforms of both pulse waves can be measured by the time difference between the rising points with the most distinct characteristics, which are the inflection points of the waveforms. However, since the width of the inflection point is about 10 msec even at the rising point, a measurement error of 5 to 10% occurs.

Furthermore, it is known that the pulse wave velocity changes in proportion to the internal pressure of the artery, that is, the blood pressure, and changes by about 5 to 10% for a blood pressure of 10 mmHg. To determine the level of blood pressure, it is necessary to specifically measure blood pressure and compare it under the same conditions.

(Objective of the present invention) An object of the present invention is to measure the degree of arterial stiffness based on the slow velocity of vascular opening propagation velocity using simple equipment and simple operations. The objective is to quickly measure the degree of arteriosclerosis.

(Characteristics of the present invention) When a cuff used for blood pressure measurement is wrapped around the upper arm, for example, and the pressure of the cuff is increased above the systolic blood pressure, a part of the artery is pressed and occluded, and the pressure of the cuff becomes higher than the systolic blood pressure. When the blood pressure is low and higher than the diastolic blood pressure, each time the blood pressure becomes higher than the cuff pressure, the blood vessels open sequentially from upstream to downstream as shown in Figure 3a, and blood periodically flows out while repeating the opening movement. It will flow.

It has been found that when pressure sensors are provided at the upstream and downstream portions of the inner periphery of the cuff, pressure with rapid changes is applied to both pressure sensors with a time difference corresponding to the opening timing of the blood vessel.

Based on the above findings, the present invention provides that when a certain section of the artery is appropriately pressed from the outside to occlude it and then the pressure is reduced, the artery opens sequentially from the upstream part to the downstream part. In addition to converting steep pressure change components into pulses and extracting them,
The main feature is that the difference in pulse generation time between upstream and downstream sections is measured.

(Example) Examples of the present invention will be described in detail below with reference to the drawings.

FIG. 1 illustrates the measuring device of the present invention, in which an upstream pressure sensor 2 and a downstream pressure sensor 3 are mounted inside a blood vessel pressurizing means such as a cuff 1 suitable for wrapping around the upper arm. a measuring section M that is attached at regular intervals so that the pulse waveform of the artery and the opening movement of the blood vessel can be detected as electrical fluctuations in the pressure waveform; Cuff pressure control section C for controlling internal pressure and pressure sensors 2 and 3 in measurement section M
a two-channel signal processing unit SP for processing signals from the signal processing unit SP; a data processing unit DP for processing the signals from the signal processing unit SP using a microcomputer;
It consists of a digital display section D provided in association with the data processing section DP, and a printer P that can print hard copies as needed.

The cuff pressure control section C is equipped with a pressure pump 4 and a leak valve 5 that operate according to instructions from the data processing section DP to adjust the air pressure inside the cuff 1. A/D
A converter 7 is provided so that the cuff internal pressure can be obtained as a digital signal and then applied to the data processing section DP, and the signal processing section SP is equipped with an amplifier 8, a high-pass filter 9, and a level setting device 10. A data processing section is provided with a pair of processing circuits consisting of a comparator 11 to process the signals from both pressure sensors 2 and 3 separately and convert them into pulse waves.
Furthermore, a start switch 12 and a print switch 13 are provided in connection with the data processing section DP, and the pressure sensors 2 and 3 provided on the cuff 1 in the measurement section M are thin diaphragm type pressure sensors. A film-type device using a polymeric piezoelectric material in the form of a piezoelectric material or a band-like material is suitable.

If the pressure inside the cuff 1 is made higher than the systolic blood pressure to press and occlude the artery as shown in Figure 1, and then the pressure inside the cuff 1 is moderately lowered, the pressure inside the cuff becomes lower than the systolic blood pressure. When the blood pressure is maintained higher than the diastolic blood pressure, as shown in FIG. It can be seen that the detected pressures a ₁ and a ₂ with steeply rising pressure waveforms can be obtained.

It goes without saying that the cuff 1 may be any other blood vessel pressurizing means capable of applying pressure to the blood vessel from the outside and gradually changing the degree of pressurization.

A case in which the vascular opening propagation velocity is measured using the above device will be described below.

First, when the cuff 1 is wrapped around the upper arm of the person to be measured and the start switch 12 is turned on, the leak valve 5 is closed and the pressurizing pump 4 is started, supplying air into the cuff 1 and closing the cuff. Pressure 1. The pressure inside the cuff during pressurization is measured with the pressure gauge 6, digitized, and then applied to the data processing unit DP, and while being read by the data processing unit DP, pressurization is continued until the preset pressure is reached, and the set pressure is reached. When the data processing unit DP detects that the
to stop. If the blood pressure of the subject is higher than the set value at this point, an impulse to open the blood vessel is generated immediately, and this is processed by the data processing unit.
The DP determines that pressurization is insufficient, and the pressurization pump 4 is started again to increase the pressure of the cuff 1 to a certain degree. Cuff 1
When the pressure is the same as or slightly higher than the patient's systolic blood pressure, only the part of the upstream side of the blood vessel corresponding to the cuff 1 opens and closes, as shown in FIG. 3b.
Furthermore, if the pressure of cuff 1 is increased to make it higher than the patient's systolic blood pressure, the blood vessel in the area corresponding to cuff 1 will become occluded due to the pressure, and within a certain period of time after cuff 1 is pressurized. After confirming that no blood vessel opening pulse is generated, the leak valve 5 is slightly opened to reduce the pressure inside the cuff 1 at a constant speed, and the pressure sensors 2 and 3 detect the pressure change accompanying the blood vessel opening. The pressure waveforms obtained by the pressure sensors 2 and 3 are amplified by an amplifier 8, converted into a pulse waveform by a high-pass filter 9 and a comparator 11, and monitored by a data processing unit DP. Immediately after starting to reduce the pressure inside cuff 1, the pressure inside cuff 1 is higher than the systolic blood pressure of the blood vessels near cuff 1, so the blood vessels under cuff 1 are pressed and occluded by external pressure, and blood flow stops. The state will be as follows.
During the process of gradually reducing the pressure inside the cuff 1 by releasing air through the leak valve 5, when the pressure inside the cuff 1 falls below the maximum blood pressure in the blood vessel, a phase occurs where the pressure inside the blood vessel becomes higher than the outside pressure, resulting in occlusion. Blood vessels open and blood flows.

Intravascular pressure is the pressure generated by the pumping action of the heart, so it changes over time in synchronization with the contraction of the heart. Therefore, intravascular pressure temporarily overcomes external pressure and opens the blocked blood vessel. However, it closes in a short period of time, and such blood vessel opening and closing movements do not occur simultaneously in the entire area of the blood vessels under the cuff 1, but rather open and close from the upstream blood vessels near the heart first, as shown in Figure 3a. After a certain period of time, the blood flow is blocked as it propagates downstream. Cuff 1
Since two pressure sensors 2 and 3 are installed on both the upper and lower sides, first, as shown in Fig. 2, the upstream pressure sensor 2 is set at 10 mm, which indicates the opening of the blood vessel, as shown in b ₁ .
It is possible to obtain an extremely steep waveform that rises at seconds, and the width of the inflection point is 1 to 2 msec, making it possible to pinpoint the position extremely accurately. Next, a similar pressure waveform b ₂ is obtained at the downstream pressure sensor 3, and both waveforms a ₁ indicating the blood vessel opening are obtained at both the upper and lower pressure sensors 2 and 3.
and _a2 have a time difference of 50 to 80 msec, and are converted into pulses by the signal processing unit SP, so that the blood vessel opening time difference can be obtained as the interval between two pulses, as shown by _c1 and _c2 in FIG.

The time difference obtained by the above pulse is the time during which the opening phenomenon of the blood vessel is transmitted under the two pressure sensors 2 and 3, and from the distance between both pressure sensors 2 and 3, the microcomputer in the data processing unit DP calculates the propagation of the opening of the blood vessel. You can find the speed. That is, the time difference T between both impulses is measured by the microcomputer, and the pressure sensors 2 and 3 are
The vessel opening propagation velocity is
= I/T, and since the pressure waveforms detected by both pressure sensors 2 and 3 have steep rising waveforms, highly accurate measurement is possible despite processing by a simple signal processing circuit. The obtained vessel opening propagation velocity is processed by the data processing section.
The data can be stored in the microcomputer in the DP, digitally displayed on the display D after the measurement is completed, and printed in hard copy by the printer P by operating the print switch 13 if necessary.

Waveforms a1 and ₁ obtained during the opening process of the blood vessel
_a2 occurs once per heartbeat when the pressure in the cuff 1 is between the systolic blood pressure and the diastolic blood pressure, so until the pressure in the cuff 1 reaches the same pressure as the diastolic blood pressure due to pressure reduction by the leak valve 5, That is, the propagation velocity can be measured repeatedly in one measurement, and the measurement results can be averaged by a microcomputer to further improve measurement accuracy.

In the process of measuring the vascular opening propagation velocity, the waveform representing the vascular opening obtained initially by starting pressure reduction by slowly releasing air from the leak valve 5 after raising the internal pressure of the cuff 1 above the systolic blood pressure is Since the pressure inside the cuff 1 almost coincides with the maximum value of blood pressure, the pressure inside the cuff 1 at this time is measured by the pressure gauge 6, and the pressure inside the cuff 1 is measured by the A/D converter 7.
It is possible to know the systolic blood pressure by digitizing it, and in the process of reducing the pressure inside the cuff 1, if the pressure inside the cuff 1 becomes below the diastolic blood pressure, 1
Because the intravascular pressure is higher than the external pressure at any point in the heartbeat, the blood vessels are open during all time phases, and no opening/closing phenomenon occurs and no pressure waveform indicating blood vessel opening is generated. Since the point at which the pressure waveform disappears is the point at which the pressure inside the cuff 1 is almost equal to the diastolic blood pressure, the pressure inside the cuff 1 at this point is measured and digitized by the pressure gauge 6 and the A/D converter 7 to find the minimum value. You can know your blood pressure.

After the pressure waveform indicating the blood vessel opening disappears, the pressure waveform obtained by the pressure sensor is a normal pressure pulse wave itself, and the compression pressure at the time of recording is constant, and a waveform with little distortion and large amplitude is obtained. Above, if an A/D converter 14 is separately provided on the output side of both amplifiers 8 and the output signal thereof can be applied to the data processing section DP, the A/D converted waveform can be transmitted to the microcomputer. After the measurement is completed, the waveform can be displayed on the printer P, and can therefore be used as a pulse waveform.

After the recording of the pulse waveform is completed, the leak valve 5 is fully opened to complete the measurement, and the measurement result is digitally displayed on the display section D. Also, print switch 13
Turn on and print the measurement results and pulse waveform.

When measuring blood vessel aperture propagation velocity and blood pressure, noise from external vibrations often enters, making it difficult to distinguish between noise and signals, but with the above device,
There are pressure sensors 2 and 3, and the noise generates pulses in the same phase, so there is no phase shift like in the case of a blood vessel opening waveform, and therefore the pressure waveform detected by both pressure sensors 2 and 3 is Since it can be easily distinguished by the microcomputer in the data processing unit DP, highly accurate measurement is possible.

In addition to the above, the repetition period of the blood vessel opening waveform is
Since it corresponds to the heartbeat period, extremely accurate measurements of the heart rate can be carried out in addition to the measurements described above, i.e. the time from the occurrence of a pulse c ₂ to the occurrence of the next pulse c ₂ shown in FIG. Data processing part DP
It can be measured using a microcomputer.

(Effects) As explained above, according to the present invention, the arteries are pressurized under moderate pressure to cause them to open and close, and the opening phenomenon is detected as an electrical signal by a sensor in each of the upstream and downstream parts. After detection, it is converted into a pulse signal by a signal processing unit with a high-pass filter function, and the vascular opening propagation velocity is measured based on the time difference between both pulse signals.
As a result, measurements can be performed with simple equipment and simple operations, making it extremely easy to diagnose the degree of arteriosclerosis.
Moreover, compared to conventional arteriosclerosis measurement devices based on pulse wave velocity, the propagation time is 10 times longer, the width of the inflection point is 1/10, and the distance between two points for pressure detection is fixed. High-precision measurement is possible because there are no errors, measurement values do not change due to blood pressure, and are not easily affected by noise. Furthermore, measurement operations are simple and data processing after detection is easy. Since it is significantly simpler than conventional measuring devices, measurement results can be obtained in a short time, and the time required is 1/5 of that of conventional devices, allowing for highly efficient measurement. This is possible.

[Brief explanation of drawings]

FIG. 1 is a block diagram illustrating the apparatus of the present invention, FIG. 2 is a waveform diagram for explaining the correlation of each waveform, and FIG. 3 is a longitudinal sectional view for explaining the blood vessel opening process. 1... Cuff as blood vessel pressurizing means, 2... Upstream pressure sensor, 3... Downstream pressure sensor, 4...
Pressure pump, 5... Leak valve, 6... Pressure gauge, 7
...A/D converter, C...cuff pressure control section, M...
Measurement section, SP...signal processing section, DP...data processing section, D...display section.

Claims (1)

[Scope of Claims] 1. An upstream pressure sensor and a downstream pressure sensor are attached to the inner side corresponding to the artery portion at a constant interval, and the degree of pressurization is simultaneously and gradually changed between the two pressure sensors. A blood vessel pressure means configured to occlude the entire area of the corresponding blood vessel is provided between both pressure sensors, and in order to output a steep pressure change signal accompanying the opening of the occluded blood vessel as a pulse, it is equipped with an amplification function and a high-pass A signal processing unit having a filter function is provided to apply the detection signals from both pressure sensors, and
A data processing section built in a microcomputer that monitors the pulses output from the signal processing section and measures the vascular opening propagation velocity from the time difference between the two pulses, and a display section that displays the processing results of the data processing section. Characteristic vascular opening propagation velocity measuring device. 2. An upstream pressure sensor and a downstream pressure sensor are attached to the inner side corresponding to the artery part with a constant interval maintained, and the degree of pressurization can be simultaneously and gradually changed in height between both pressure sensors. A pneumatic blood vessel pressurization means equipped with a pressure pump and a leak valve is provided at the pressure pump, and after the entire area of the blood vessel corresponding to the gap between both pressure sensors is occluded by pressurization by the pressure pump, the blood pressure is lower than the systolic blood pressure. The structure is configured such that the occluded blood vessel can be sequentially opened from the upstream side under a low pressurizing force, and both pressure sensors include a signal processing unit for outputting a steep pressure change signal in the opening process of the blood vessel as a pulse. This signal processing unit has an amplification function, a high-pass filter function that can output steep pressure changes during the blood vessel opening process as a detection signal with an inflection point width of about 1 to 2 msec, and a comparator function. The apparatus further includes a data processing section built in a microcomputer that monitors the pulse output from the signal processing section and measures the vascular opening propagation velocity from the time difference between the two pulses, and a display section that displays the processing results of the data processing section. A blood vessel aperture propagation velocity measuring device characterized by: