JPH0755217B2 - Pulse wave detector - Google Patents

Description

TECHNICAL FIELD The present invention relates to a pulse wave detecting device, and more particularly to a pulse wave detecting device capable of non-invasively detecting an aortic wave.

[Conventional technology]

Blood pressure measurement and pulse wave analysis are necessary for the diagnosis of cardiovascular disease. Especially for the diagnosis of heart disease, analysis of aortic waves near the heart is extremely effective. The method of measuring this aortic wave is divided into an open method and a non-open method.
As an open method, a blood vessel catheter measurement method has been conventionally used. This method involves inserting a catheter into the artery,
This is a method of directly measuring the pulse wave at the site by inserting a catheter to the site to be measured. on the other hand,
As a non-invasive method, a method using an ultrasonic wave or a nuclear magnetic resonance method has been developed and put to practical use.

[Problems to be Solved by the Invention]

However, the above-mentioned open blood vessel catheter measuring method is a large-scale method of inserting a catheter into an artery, and it is not preferable because it imposes a great physical and mental burden on the patient. On the other hand, the noninvasive method reduces the burden on the patient, but has the problem that the pulse wave having a specific blood pressure value cannot be measured. That is, only the shape of the pulse wave can be obtained by non-invasive measurement, and the blood pressure value cannot be detected simultaneously. Therefore, the blood pressure value needs to be measured by another method. Simultaneous measurement of pulse waves with specific blood pressure values is essential in the diagnosis of heart disease,
A pulse wave obtained by a conventional non-invasive method is not sufficient for diagnosis.

Therefore, it is an object of the present invention to provide a pulse wave detection device capable of simultaneously detecting a pulse wave and a blood pressure value by a non-invasive method.

[Means for Solving the Problems]

A first invention of the present application is, in a pulse wave detecting device, an ischemic sac having a size required to occlude an upper arm, and a pulse wave passing through the ischemic sac is a pressure generated by collision of the pulse wave. A sash having a detection bag having a size suitable for detecting as fluctuation, a sound wave sensor for detecting Korotkoff sound generated by wearing the sash, and a pressure sensor for detecting pressure fluctuation generated in the detection bag. Then, the reference internal pressure of the ischemic sac and the detection sac is gradually decreased from a sufficiently high value, and when the volume of the Korotkoff sound detected by the acoustic sensor reaches a value indicating diastolic pressure, the reference internal pressure is kept at a constant value. And a pulse wave detecting device for outputting the pressure fluctuation obtained from the pressure sensor as an aortic wave near the heart while the reference internal pressure is maintained at a constant value. And .

The second invention of the present application is, in the above-described pulse wave detecting device, when the volume of the Korotkoff sound is maintained at a substantially constant value despite the decrease of the reference internal pressure, the reference internal pressure is increased in reverse, and the Korotkoff is increased. When the volume of the sound becomes larger than a certain value to some extent, it is determined that the value indicating the diastolic pressure is reached, and the reference internal pressure is maintained at a certain value.

[Operation] The present invention has discovered the basic principle that, when a tie band is wrapped around the upper arm and pressure is applied to the tie band under predetermined conditions, a pulse wave equivalent to the aortic wave is obtained in the upper arm. based on. Applying sufficient pressure to the bandage can block the upper arm. Here, when the pressure of the binding band is gradually reduced, a pulse wave passing through the binding band is detected. This pulse wave is a small wave at first, but gradually increases as the pressure on the bandage decreases. The inventor of the present application has found out that when the pressure of the bandage matches the diastolic pressure DP, the pulse wave detected through the bandage becomes equivalent to the aortic wave in the vicinity of the heart. is there. The pulse wave detection device according to the present invention monitors the Korotkoff sound, and when the Korotkoff sound reaches a predetermined set value, it is determined that the pressure of the binding band has reached the diastolic pressure DP. The pressure control means of this device has a function of maintaining the reference internal pressure of the binding band at a constant value when the Korotkoff sound reaches a set value. Therefore, the pulse wave output by the pulse wave output means during this period is equivalent to the aortic wave in the vicinity of the heart. Thus, a pulse wave equivalent to this can be measured in the upper arm without directly measuring the pulse wave near the heart.

〔Example〕

Hereinafter, the present invention will be described based on illustrated embodiments. FIG. 1 is a block diagram showing the basic configuration of a pulse wave detecting device according to an embodiment of the present invention. This device is roughly divided into two main parts, a device main body 100 (enclosed by a chain line) and a binding band 200. The bandage 200 has an ischemic sac 210 for occluding the upper arm and a detection sac 220 for detecting a pulse wave passing through the ischemic sac. The ischemic sac 210 has a sufficient size for ischemia, and in the case of the present embodiment,
The length l1 of the figure is about 10 cm. Further, the detection sac 220 is made sufficiently smaller than the ischemic sac 210, and in the case of this embodiment, the length l2 in the figure is about 2 cm. If the detection bladder 220 is too large, the air volume becomes large, so that the pulse wave colliding with the detection bladder cannot be sufficiently detected. The blood flow blocking sac 210 and the detection sac 220 are connected to each other at a connecting path 230 on the way,
A conduit 240 for letting air pass extends from the bladder sac 210 to the outside, and a conduit 250 also extends from the detection sac 220 to the outside. The binding band 200 is worn on the upper arm in the orientation shown in FIG.

On the other hand, the device main body 100 has the following configuration. First, in the pipe line 101 to which the conduit 250 is connected, a sound wave sensor
A 110 and a pressure sensor 120 are provided. Here, both of the sensors are, in principle, sensors for measuring the pressure in the detection bag 220 guided through the conduit 250, but the pressure sensor 120 detects the pressure fluctuation in the frequency band of the pulse wave. On the other hand, the sound wave sensor 110 is designed to detect the frequency band of sound waves, particularly the frequency band of Korotkoff sounds (30 to 80 Hz). The analog signal detected by the sound wave sensor 110 is
The signal is amplified by the amplifier 111, converted into a digital signal by the A / D converter 112, and given to the CPU 130. Similarly, the analog signal detected by the pressure sensor 120 is amplified by the amplifier 121, converted into a digital signal by the A / D converter 122, and converted into a CP signal.
Given to U130. An air pump 140 and a leak valve 150 are connected to the pipeline 102 to which the conduit 240 is connected. This air pump 140 and leak valve 150 are CP
Controlled by U130. The conduit 101 and the conduit 102 are connected to each other, and the ischemic sac 210 and the detection sac 220 are connected to each other by a connecting path 230.
Are connected by. Therefore, the ischemic sac 210 and the detection sac 220
Is essentially kept at the same pressure. However,
Due to the large volume of the ischemic sac 210, high frequency pressure fluctuations appear only in the detection sac 220. For this reason, the sound wave sensor 110 and the pressure sensor 120 are preferably connected in the vicinity of the conduit 250. The CPU 130 has a memory 160 for storing data and a display device 17 for displaying data.
A printer 180 for outputting 0 and data is connected.

Now, a brief description will be given of what an aortic wave to be measured by this device is like. FIG. 3 shows the basic waveform of this aortic wave. As shown in this figure, all the pulse waves are shown with the horizontal axis as the time axis and the vertical axis as the pressure axis.
This aortic wave is a wave wave that shows blood pressure fluctuations near the heart, and directly represents the movement of the left ventricular muscle of the heart. In FIG. 3, the heart is in the diastole until time t1, and the pressure becomes the diastole pressure DP. From time t to t2, the heart performs contracting motion, and the pressure rises to the systolic pressure SP. Subsequently, the heart turns into diastolic movement, but at time t3, the aortic valve closes, so that a small peak appears at time t4. This peak is called the aortic valve closure scar. After this, the time
The pressure gradually decreases from t4 to t5 and returns to the diastolic pressure DP again. Such a pressure fluctuation appears for each beat of the heart, and it propagates from the heart through the arteries and is propagated as a pulse wave to the whole body. However, the pulse wave thus generated in the heart changes its waveform as it propagates to the periphery. This is shown in FIG. Waveforms WA to WF are the results obtained by measuring the pulse wave at the site 0 cm to 50 cm away from the position directly above the aortic valve of the heart to the periphery by the vascular catheter measurement method. Here, the waveform WA corresponds to the aortic wave near the heart shown in FIG. In this way, the high-frequency component is increasing as it goes to the periphery, and the maximum blood pressure value TOP
It can be seen that is increasing. It is considered that this is because blood vessels become thinner toward the periphery and resistance increases. In addition, MVP is an aortic closure scar pressure here. In this way, the pulse wave changes its waveform as it goes to the periphery, so the pulse wave normally measured in the upper arm (for example, the pulse wave WF) is considerably different from the aortic wave in the vicinity of the heart. According to this device, a pulse wave equivalent to the aortic wave can be obtained in the upper arm.

FIG. 5 (a) is a graph for explaining the measurement operation by this device, and FIG. 5 (b) is a partially enlarged view thereof. As mentioned above, this device uses an air pump 140 and a leak valve 150.
And can control the pressure in the ischemic sac 210 and the detection sac 220. That is, when increasing the pressure,
When the air pump 140 is operated to send air into the bladder to reduce the pressure, the leak valve 150 can be opened to leak the air in the bladder.

At the time of measurement, a strap 200 is worn on the upper arm of the subject as shown in FIG. 2, and a measurement start switch (not shown) is pressed. The graph in FIG. 5 (a) shows the change in intracapsular pressure after the start of measurement. That is, after the measurement is started, the CPU 130 activates the air pump 140 to send air into the capsule to gradually increase the pressure (point A to the graph).
The ischemic sac 210 gradually squeezes the artery, and eventually reaches a pressure for complete ischemia (point B). FIG. 6 (a) is a cross-sectional view showing the relationship between the bandage 200 (the ischemic sac 210 and the detection sac 220) and the artery 300 at this time. The left side of the figure is the heart, the right side is the periphery, and the pulse wave should be transmitted from left to right.
Due to the high pressure of 0, the pulse wave cannot pass through the ischemic sac 210. Subsequently, the CPU 130 gradually opens the leak valve 150 to gradually reduce the pressure (point C-).
Then, Korotkoff sound is generated at the point D. The waveform K in the graph shows the amplitude of the Korotkoff sound obtained corresponding to each pressure value when the pressure is gradually decreased from the point D. In this way, the Korotkoff sound is generated after passing the point D because a part of the pulse wave starts passing through the ischemic sac 210 against the pressure of the ischemic sac 210, as shown in FIG. 6 (b). Is. The pressure corresponding to this point D is the systolic pressure.
It is known to correspond to SP. When the pressure is further reduced from the point D, the pulse wave becomes easier to pass through as shown in FIG. 6 (c), and the Korotkoff sound becomes maximum at the point E. After that, the Korotkoff sound gradually decreases, and when reaching the point F, the sound becomes very small, and the amplitude is substantially constant.
It is known that the pressure corresponding to this point F corresponds to the diastolic pressure DP, which corresponds to the state of FIG. 6 (d). The feature of this device is that if the pressure is reduced to point F, this pressure DP
Is maintained for a while (points F to G), during which the pulse wave is detected. When the detection of the pulse wave is completed, the pressure is further reduced (point G to point H). The binding band 200 is floated from the artery 300 as shown in FIG. 6 (e). In case of continuing the measurement again, after increasing the pressure from point H to point I, decrease the pressure from point I to point J (diastolic pressure DP) and keep the pressure constant. Then, the pulse wave detection may be performed again. If the diastolic pressure DP is stored when the point F is reached, the pressure is increased to the point I (a pressure slightly higher than the diastolic pressure DP) without increasing the pressure to the point B. After that, if the pressure is reduced to the diastolic pressure DP, remeasurement is possible.

Now, let's explain the pulse wave detection method. Since the pulse wave is a pressure fluctuation in the artery 300, it is measured as a pressure value. As shown in FIG. 6, the pulse wave 310 passing through the ischemic sac 210 collides with the detection sac 220. Since the detection sac 220 has a smaller capacity than the ischemic sac 210, it is possible to delicately detect such a wave having a high frequency and a small amplitude. This subtle pressure fluctuation is detected by the pressure sensor 120. Since the ischemic sac 210 has a large capacity, pressure fluctuation due to the pulse wave is not so much received. Here, focusing on the pressure value itself detected by the pressure sensor 120, it can be seen that two elements are superposed. That is, one is the pressure of the ischemic sac 210 and the other is the pressure fluctuation due to the pulse wave of the detection sac 220. Here, the former will be referred to as a reference internal pressure, and the latter will be referred to as a pulse wave pressure. Since the detection bladder 220 is connected to the ischemic bladder 210 via the connection path 230, when the pulse wave does not collide, the pressure of the detection bladder 220 also becomes the reference internal pressure. The graph shown in FIG. 5 (a) shows this reference internal pressure, and the pressure detected by the pressure sensor 120 is actually the reference internal pressure superposed with the pulse wave pressure. An enlarged view of the portion L of FIG. 5 (a) is shown in FIG. 5 (b). In this enlarged view, the graph of the pressure value in which the pulse wave is superimposed on the reference internal pressure (shown by the broken line in the figure) is shown by the solid line. In the section from point F to point G in the figure, the reference internal pressure is maintained at the diastolic pressure DP as described above, and the pulse wave is on the diastolic pressure DP.

As shown in FIG. 4, the pulse wave in the upper arm (for example, pulse wave WF) is different from the aortic wave (pulse wave WA). However, when the ischemic sac 210 is maintained at the diastolic pressure DP, the pulse wave detected by the detection sac 220 is equivalent to the aortic wave even though it is detected in the upper arm. Was found. Although it is difficult to perform a rigorous theoretical analysis of this reason, the present inventor believes that the high frequency component of the pulse wave is cut because the ischemic sac 210 functions as a low pass filter. As shown in FIG. 4, in the pulse wave, high frequency components are extended toward the periphery due to an increase in vascular resistance. However, when the pulse wave of the upper arm (pulse wave WF) passes through the ischemic sac 210, this high-frequency component is cut, and a wave equivalent to the original aortic wave (pulse wave WA) is filtered out. be able to. Therefore, the width of the ischemic sac 210 (ll in FIG. 1) needs to be wide enough to fulfill the function of this low-pass filter.
In general, it has been experimentally confirmed that this function can be achieved if the distance is 9 cm or more. Since a wave equivalent to the aortic wave is obtained when the pressure of the ischemic sac 210 is equal to the diastolic pressure DP, as shown in FIG. 5 (a), the reference internal pressure is the diastolic pressure.
If the pressure is maintained constant at the point F reaching the DP and the pulse wave is detected in the section from the point F to the point G, the pulse wave can be treated as an aortic wave. In the measurement again, the pulse wave after the point J can also be treated as an aortic wave.

Here, what kind of pulse wave is obtained when the ischemic sac 210 is not in the diastolic pressure DP (that is, the section other than the points F to G) will be described for reference. FIG. 7 is a diagram showing various pulse waves detected in the section from point D to point H in FIG. 5 (a). The waveform shown by the solid line in the figure shows the pulse wave detected by the pressure sensor 120 of this device, and the waveform shown by the broken line shows the pulse wave in the upper arm (pulse wave WF in FIG. 4). Also,
The sign above each pulse wave indicates that each pulse wave is a pulse wave detected at each point in the graph of FIG. The unsigned pulse wave is the pulse wave detected at these midpoints. In this way, when the pressure is gradually decreased from the point D, the amplitude of the detected pulse wave gradually increases. Then, when reaching the point F (to the point G), the amplitude of the pulse wave becomes maximum, and thereafter, the amplitude of the pulse wave decreases. Point F
Comparing the pulse wave of the solid line with the pulse wave of the broken line, it can be seen that the high frequency component is cut. It should be noted that the amplitude of the detected pulse wave is not necessarily proportional to the amplitude of the Korotkoff sound. Fifth
As shown in FIG. 7A, the Korotkoff sound peaks at the point E, but as shown in FIG. 7, the pulse wave does not peak at the point E. At points F to G, a tie belt 20
It is considered that the relationship between 0 and the artery 300 is in the state as shown in FIG. 6 (d). That is, the reference internal pressure of the bandage 200 and the arterial diastolic pressure DP antagonize each other, and the pulse wave causes
It is possible to sufficiently pass 0, and it is possible to give a sufficient impact to the detection bag 220. If the pressure of the binding band 200 is higher than this, the pulse wave cannot sufficiently pass through the ischemic sac 210 and a sufficient impact is applied to the detection sac 220, as shown in FIGS. There is no. If the pressure of the binding band 200 is lower than this, as shown in FIG.
Is separated from the artery 300, so that even if the pulse wave sufficiently passes through the ischemic sac 210, the detection sac 220 is not sufficiently impacted.

As described above, the pressure sensor 120 is provided between the points F and G.
Is detected and the pulse wave is captured by the CPU 130 as a digital signal. In this device, the captured pulse wave data is temporarily stored in the memory 160. Then, as shown in FIG. 5 (b), five consecutive pulse waves are detected between points F and G, and each of the five pulse wave data and the waveform of the average pulse wave are detected. It is output by the printer 180. Also,
The systolic pressure SP value corresponding to the point D, the diastolic pressure DP value corresponding to the point F, and the pulse rate are displayed on the display device 170.

By the way, the CPU 130 controls to maintain the pressure at a constant value when the point F is reached, but it is difficult to accurately determine that the point F is actually reached. As aforementioned,
The determination that the point F has been reached is made by detecting that the Korotkoff sound has become small and the amplitude has not changed, but since the pressure is being reduced at a constant speed, the CPU 130 recognizes that the point F has been reached. When this happens, it is likely that the actual pressure has already passed point F and has become even lower. Therefore, in this device, although the principle of pulse wave detection is performed by the pressure control as shown in the graph of FIG. 5 (a), the pulse control is actually performed as shown in FIG. 8 (a). Wave detection is performed. That is, the pressure is reduced according to the above-described principle from the point D to the point F.
Even after passing the point F, the pressure is further reduced. Here, the amplitude of the Korotkoff sound is constantly monitored, and if the Korotkoff sound amplitude does not change even after the decompression continues for a predetermined time, the decompression is stopped and the pressure is increased on the contrary.
F1). Then, the amplitude W of the Korotkoff sound at this point F1
When the amplitude of the Korotkoff sound increases to kW (k is a predetermined coefficient, for example, k = 1.5), the pressure is kept constant there (point F2). FIG. 8 (b) is an enlarged view of the portion M of FIG. 8 (a), showing this state in more detail. As is clear from this enlarged view, strictly speaking, the point F that gives the diastolic pressure DP is not the first point F0 at which the amplitude of the Korotkoff sound becomes the constant value W, but the point one beat before it. Is. It was confirmed that if the amplitude of the Korotkoff sound at this point F is kW, then k = 1.5. Therefore, if the pressure is reduced to the point F1 as described above, the pressure is increased conversely, and the place where the amplitude of the Korotkoff sound becomes 1.5 times, that is, the point F2 can be treated as a point equal to the diastolic pressure DP. it can. Although the value of the coefficient k varies depending on the patient, no problem occurs in the accuracy of detecting the aortic wave.

Finally, FIGS. 9 and 10 show the aortic waves near the heart detected by this device. FIG. 9 is an aortic wave of a normal person, and FIG. 10 is an aortic wave of a heart diseased person. The aortic wave thus obtained matches the aortic wave invasively measured by the conventional vascular catheter measuring method. In addition, the measured value of blood pressure is obtained on the vertical axis and the actual time value is obtained on the horizontal axis, which is characteristic in that not only the waveform of the pulse wave but the actual blood pressure value is obtained. Thus, knowing the blood pressure value together with the waveform is very useful for comprehensive judgment of heart disease.

Although the present invention has been described above with reference to an embodiment, the present invention is not limited to this embodiment. In short, the present invention is based on the discovery of the basic principle that, when a tie band is wrapped around the upper arm and pressure is applied to the tie band under predetermined conditions, a pulse wave equivalent to the aortic wave is obtained in the upper arm. . Any device configuration may be adopted as long as the pulse wave can be detected based on this basic principle. For example, although the Korotkoff sound recognizes that the tether pressure equals the diastolic pressure DP in the above-described embodiment, other methods of recognition could be used. Further, also in the case of performing recognition by Korotkoff sounds, methods other than those described in the above-described embodiments can be considered. For example, a microphone may be provided near the detection bag and the Korotkoff sound may be detected by this microphone.

Further, the binding band is not limited to the one described in the above embodiment, and another binding band may be used. Figure 11 shows an example of this other binding band. As is clear from comparison with the binding band shown in FIG. 1, only the conduit 250 is led out from this binding band, and no conduit is led out from the ischemic sac 210. FIG. 12 shows a state in which this binding band is attached. Ischemic sac 21
Since 0 is connected to the detection bag 220 via the connection path 230, the pulse wave detection according to the present invention is possible even if only one conduit 250 is used. Rather, it is preferable to use the binding band having only one conduit in this way, because it has the following advantages.

(1) If there are two conduits, a connection error with the device main body 100 (a mistake connecting the two conduits in reverse) will occur, but if there is one, such an error will not occur.

(2) Since only the connecting path 230 serves as an air inlet / outlet port with respect to the ischemic sac 210, the pressure fluctuation detection gain is improved.

(3) Since there is only one conduit, it is possible to reduce the weight and cost.

〔The invention's effect〕

As described above, according to the present invention, since the aortic wave can be detected by attaching the binding band to the upper arm, it is possible to easily measure the waveform and the blood pressure value of the aortic wave in a non-invasive manner. Become.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a pulse wave detecting device according to an embodiment of the present invention, FIG. 2 is a diagram showing a state in which the binding band in the device of FIG. 1 is attached to an upper arm portion, and FIG. Waveform diagram of a general aortic wave, Fig. 4 is a diagram showing the deformation of the pulse wave from the heart to the peripheral area, Fig. 5 is a graph explaining the measurement principle by the device shown in Fig. 1, and Fig. 6 is FIG. 7 is a sectional view showing the relationship between the binding band pressure and the passing state of the pulse wave, FIG. 7 is a waveform diagram showing the relationship between the binding band pressure and the detected pulse wave, and FIG. 8 is an actual view by the device shown in FIG. Fig. 9 shows the first graph for explaining the measurement operation of
FIG. 10 is a waveform diagram showing an aortic wave of a normal person detected by the apparatus shown in FIG. 10, FIG. 10 is a waveform diagram showing an aortic wave of a diseased person detected by the apparatus shown in FIG. 1, and FIG. 11 is another embodiment of the present invention. FIG. 12 is a view showing a binding band used in the example, and FIG. 12 is a view showing a state where the binding band shown in FIG. 11 is attached to an arm portion. 100: device main body, 101, 102 ... conduit, 200 ... binding band, 210
...... Ischemic sac, 220 ...... Detection sac, 230 ...... Connection path, 240,250
…… Conduit, 300 …… Artery, 310 …… Pulse wave, SP …… systolic pressure, DP …… diastolic pressure, K …… Korotokov sound waveform.

Claims (2)

[Claims] 1. An ischemic sac having a size required to occlude an upper arm, and a pulse wave passing through the ischemic sac are suitable for detecting pressure fluctuations caused by collision of the pulse waves. A binding band having a detection bladder having a size, a sound wave sensor detecting a Korotkoff sound generated by wearing the binding band, a pressure sensor detecting a pressure fluctuation generated in the detection bladder, the blood flow blocking sac and the The reference internal pressure of the detection bag is gradually decreased from a sufficiently high value, and when the volume of the Korotkoff sound detected by the sound wave sensor reaches a value indicating diastolic pressure, the reference internal pressure is maintained at a constant value. A pressure control means having a function; and a pulse wave detection device that outputs a pressure fluctuation obtained from the pressure sensor as an aortic wave near the heart while the reference internal pressure is maintained at a constant value. Pulse wave detection device to. 2. The pulse wave detecting device according to claim 1, wherein the reference internal pressure is increased if the volume of the Korotkoff sound is maintained at a substantially constant value despite the decrease of the reference internal pressure. The pulse wave detecting device characterized in that when the volume of the Korotkoff sound becomes larger than the certain value to some extent, it is determined that the value reaches the value indicating diastolic pressure, and the reference internal pressure is maintained at a certain value. .