JP2007202791A - Vascular pulse wave measuring apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make a precise measurement of vascular pulse waves without being affected by various external factors during the measurement. <P>SOLUTION: An optical probe A1 of a photoplethysmogram measuring device A for measuring the pulse waves of peripheral blood vessels is mounted on a finger tip of a subject E, and a cuff B1 is mounted at an upstream position of the measuring point of the photo probe A1 for constricting blood vessels to stop the blood flow therein. The vascular pulse wave measurement is made by the photoplethysmogram measuring device A/optical probe A1 after the blood flow was stopped by driving the cuff B1 for a certain time. A DC (blood flow) component signal (2), an AC (pulse wave) component signal (1) and an acceleration plethysmogram signal (3) are input to a control D respectively, and displayed on a display C after signal processing in the control D. The control D also display the cuff pressure signal (4) input to a cuff pressure controller B on the display C. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a blood vessel pulse wave measuring apparatus for measuring information related to blood vessel pulse waves.

  The blood flow sent out from the heart is transmitted to the periphery as a wave and is modified by the heartbeat and the state of the arteriole system to cause waveform distortion. Attempts have been made to evaluate the distortion of the waveform and evaluate the cardiovascular system.

  As a method for measuring a pulse wave, there are conventionally known a volume pulse wave measuring method that captures volume fluctuations in blood flow and a method of measuring a change in arterial pressure as a pressure pulse wave.

  There are various methods for measuring the volume pulse wave of the former, and fingertip photoelectric tube volume pulse wave meters that capture the amount of hemoglobin absorbed as a blood flow fluctuation have been widely used. This fingertip plethysmograph can estimate the pressure pulse wave of the nearby artery fairly accurately, and has been used mainly as a test that reflects peripheral blood circulation dynamics and autonomic nerve function.

  In recent years, an acceleration pulse wave that has been further differentiated from the primary differential waveform of the volume pulse wave to obtain a secondary differential waveform has been proposed, and by evaluating the waveform, an index of blood vessel age that reflects the sclerosis of the entire arterial system and (Patent Document 1 below).

  In addition, as a method for measuring changes in arterial pressure as a pressure pulse wave, wrist radial arterial pressure measurement method is used to measure the intra-arterial pressure (pulse wave) by removing the blood vessel wall tension by compressing the artery with a cuff (Manchette) or the like. Has been developed (Patent Document 2 below).

According to this technique, it is possible to measure the ejection wave and the reflected wave of the peripheral arterial blood vessels generated by the blood pumped from the heart, and it is considered that arteriosclerosis can be estimated by analyzing the waveform.
JP 2000-511166 A Japanese Patent No. 3184349

  Vascular pulse waves depend on both vascular organic flexibility (age and arteriosclerosis) and vascular physiological tension. The physiological tension of blood vessels is always maintained by contraction or dilation of blood vessels due to autonomic nerves or substances in the blood.

  Therefore, in order to measure only the organic flexibility of a blood vessel, it is necessary to measure the vascular pulse wave excluding these vascular tone. There are many external factors that affect autonomic nerves and substances in the blood, such as temperature, stress, drugs and exercise, bathing, meals, and biorhythms.

  For example, in the conventional volume pulse wave acceleration measurement method and wrist radial artery pressure measurement method, measurement results indicating high blood vessel age and arteriosclerosis are apparently output due to external factors such as cold water load, smoking, and simple standing load. There was a possibility.

  For this reason, in the prior art, it is necessary to always measure the subject under constant measurement conditions, but it is extremely difficult to eliminate the influence of the above external factors only by controlling the measurement conditions. There was a problem that a large and accurate diagnosis could not be made.

  In view of the above problems, an object of the present invention is to enable highly accurate vascular pulse wave measurement without being affected by various external factors during measurement.

  In order to solve the problem, in the present invention, a pulse wave measuring means for measuring a blood vessel pulse wave of a peripheral blood vessel, and a blood flow stopping means for constricting a blood vessel upstream of a measurement site of the pulse wave measuring means to stop blood flow. Then, after the blood flow is stopped by the blood flow stopping means for a predetermined time, a configuration including a control means for performing blood vessel pulse wave measurement by the pulse wave measuring means is adopted.

  According to the above configuration, when performing vascular pulse wave measurement, cuff pressure is applied at the upstream portion of the measurement site to stop the blood flow for a predetermined time, and control to perform pulse wave measurement after opening the blood vessel physiology. Highly accurate vascular pulse wave measurement can be performed without being influenced by various external factors such as the state of static tension and the presence or absence of smoking behavior.

  Hereinafter, as an embodiment of the present invention, a configuration based on photoelectric fingertip blood volume measurement and a configuration based on wrist radial artery pressure measurement are shown.

  In this embodiment, a configuration for performing pulse wave measurement based on fingertip blood volume measurement is illustrated. The fingertip blood volume measurement of the present embodiment irradiates the fingertip with light having an absorption wavelength of blood (hemoglobin) and measures the transmitted light or reflected light to measure the fingertip blood vessel pulse wave. There are advantages that can be implemented.

  As a cuff for stopping or resuming peripheral blood flow, a manual cuff or an automatic cuff used for blood pressure measurement is used. Furthermore, a measuring device such as an automatic sphygmomanometer in which the pulse wave measuring device and the cuff are integrated is also possible.

  FIG. 1 shows the configuration and measuring method of the pulse wave measuring apparatus of this embodiment.

  The apparatus of this embodiment uses a photoelectric fingertip volume pulse wave measuring apparatus A and a cuff pressure control apparatus B that controls the compression / opening (opening) of the cuff B1.

  The optical probe (A1) having a wavelength of 940 nm (absorption wavelength of blood hemoglobin) of the photoelectric fingertip volume pulse wave measurement device (A) is attached to the finger of the subject E, and the portion closer to the heart of the subject E, for example, the wrist Wear cuff B1.

  The cuff pressure control device B and the cuff B1 automatically press the blood vessel by increasing / decreasing the air pressure of the cuff B1 to automatically stop and restart the blood flow, and are used in a known automatic sphygmomanometer or the like. The configuration can be used as it is. This cuff pressure signal is displayed on the display.

  The photoelectric fingertip volume pulse wave measuring device A is a device that measures a change in blood volume of a finger of a subject E wearing the optical probe A1 as a change in light absorption amount. A known hardware configuration can be used as it is for the photoelectric fingertip volume pulse wave measuring device A and the optical probe A1.

  As schematically shown in FIG. 3, the signal output from the optical probe A1 includes an AC component signal 1 having a frequency of 0.1 Hz to 10 Hz corresponding to a pulse wave and a frequency 0 (DC) to 0. It is separated into two DC component signals 2 in the range of 1 Hz.

  As shown in FIG. 3, the original waveform (0) of the signal obtained through the optical probe A1 is obtained by the high-pass filter and the low-pass filter circuit, respectively, with the pulse wave component (1) (AC component) and the original waveform average (2) (DC Ingredients).

  Note that although the optical probe A1 measures the volume of blood, this information may be interpreted as blood flow, and therefore the signal (2) may be interpreted as average blood volume.

  The pulse wave signal (1) is input to the secondary differentiating circuit F to obtain the second-order differentiated acceleration pulse wave signal (3).

  The DC (blood flow) component signal (2), the AC (pulse wave) component signal (1), and the acceleration pulse wave signal (3) are respectively input to the control unit D, and are input to the display C through the signal processing of the control unit D. Is displayed. The control unit D also displays the cuff pressure signal (4) input to the cuff pressure control device B on the display C. For the control unit D and the display C, hardware such as a PC (personal computer) may be used. The control unit D is caused to execute software for performing blood flow stop / release control and measurement processing, which will be described later.

  In the above configuration, after the measurement of the pulse wave of the subject E is started, the blood flow is stopped for a certain time by constricting the blood vessel by applying the cuff pressure by the cuff pressure signal (4). The stop of the blood flow can be verified by the examiner on the display C as the disappearance of the pulse wave signals (1 and 3) and the decrease of the DC component (blood flow) signal (2).

  When the blood flow is stopped by the cuff B1, the blood volume of the measurement site decreases, so the amplitude of the pulse wave component of the original waveform decreases to 0, and naturally the average signal (2) of the original waveform also decreases to 0. And decrease.

  The stop time of blood flow performed by controlling the cuff pressure signal (4) is the time during which the increase in blood flow (approximately DC component signal 2) that occurs immediately after resumption of blood flow, that is, immediately after the cuff pressure is reduced to zero, is maximized. Set or set a time when the amplitude of the pulse wave of the pulse wave signal 1 is maximum.

  This is because when the blood flow becomes maximum, the blood vessel expands to the maximum, and the amplitude of the pulse wave shows the maximum value. When the measurement site is a fingertip, the blood flow stop time is considered to be about 30 to 90 seconds. The blood flow stop operation is performed for 30 seconds, 60 seconds, and then 90 seconds, and the average blood flow ( The time when the signal (2)) or the amplitude of the pulse wave (signal (1) or (3)) is maximized is selected.

  The apparatus may be configured so that an appropriate blood flow stop time can be selected by performing the blood flow stop operation for 30 seconds, 60 seconds, and then 90 seconds for each subject and measuring the blood flow. The device may be configured to use an appropriate blood flow stop time as a default from the measurement example obtained by performing the measurement, and a fixed blood flow stop time such as 30 seconds, 60 seconds, and 90 seconds may be detected. The apparatus may be configured so that it can be selected at the discretion of the person.

  Alternatively, a plurality of sets of blood flow stop / measurement of blood flow at a fixed blood flow stop time of 30 seconds, 60 seconds, 90 seconds, and subsequent blood vessel pulse wave measurement processing described below are executed, and blood flow measurement of each set is performed. Based on the result, an appropriate set of blood vessel pulse wave measurement results may be output.

  In this example, the blood flow stop operation and blood flow measurement were performed for each subject using the average blood flow as an index, and the blood flow stop time was selected.

  In the actual pulse wave measurement performed thereafter, for example, an average waveform is obtained by averaging five acceleration pulse waves before stopping blood flow. Next, an average waveform is obtained by averaging the five acceleration pulse waves measured at the time when the blood flow after the blood flow resumes becomes maximum.

  That is, for each of the amplitudes a, b, c, and d of the acceleration pulse wave shown in FIG. 2, the average amplitude value prePP of the five pulse waves before stopping the blood flow is used as the average amplitude of the five pulse waves after resuming the blood flow. A value S = (prePP / postPP) × 100 divided by the value postPP is obtained.

  FIG. 2 shows a typical pattern of the acceleration pulse wave signal (3). In FIG. 2, b / a, c / a, d / a, and e / a are indices correlated with arteriosclerosis and aging. As aging and arteriosclerosis progress, the value of b / a increases and the values of d / a and e / a decrease.

  In this example, b / a was calculated and used as an index of arteriosclerosis or blood vessel age at the measurement site. Table 1 shows the measurement results when applying various loads to the subject E.

表１から明らかなように、喫煙、呼吸停止、過呼吸などにより、カフ加圧前のｂ／ａ値（ｐｒｅｂ／ａ）は大きく変動するのに対し、カフ圧開放後のｂ／ａ値（ｐｏｓｔｂ／ａ）は変動が少ないことがわかる。

As is apparent from Table 1, the b / a value (preb / a) before cuff pressurization greatly fluctuates due to smoking, respiratory arrest, hyperventilation, etc., whereas the b / a value after cuff pressure release ( It can be seen that postb / a) varies little.

  Therefore, when performing vascular pulse wave measurement as in this embodiment, by applying cuff pressure at the upstream portion of the measurement site to stop the blood flow for a predetermined time and controlling to perform pulse wave measurement after opening, A highly accurate vascular pulse wave measurement can be performed without being affected by various external factors at the time of measurement.

  As in this embodiment, after the blood vessel is stenotic for a certain period of time to stop the blood flow, the blood flow through the blood vessel is more transient than the amount before the stenosis when the stenosis is suddenly released and the blood flow is resumed. To increase. This is a phenomenon called reactive hyperemia and is a state in which the physiological tension of blood vessels has disappeared. Therefore, by analyzing the pulse wave when the blood flow is increased after stopping the blood flow, only the organic flexibility (age and arteriosclerosis) of the blood vessel that does not depend on the physiological tension state of the blood vessel It becomes possible to measure.

  That is, according to the present embodiment, only the organic flexibility (blood vessel age and arteriosclerosis) of blood vessels can be measured without depending on the physiological state and measurement environment of the subject, and diagnosis of lifestyle-related diseases such as arteriosclerosis can be performed. There is an advantage that can be performed more accurately.

  When blood vessel pulse wave measurement is performed for the purpose of evaluating the flexibility of blood vessels as in the above embodiment, the change in pulse pressure is observed by rapidly decreasing the cuff pressure after stopping blood flow. By gradually lowering the cuff pressure later, the maximum blood pressure, the minimum blood pressure, and the average blood pressure can be measured.

  Therefore, it is possible to measure the systolic blood pressure, the diastolic blood pressure, the average blood pressure Pmean and the like of the subject E by this apparatus, and so-called normal blood pressure measurement can also be performed.

  For this reason, for example, the blood vessel pulse wave measurement function of the present embodiment can also be implemented as an additional function of an existing automatic blood pressure monitor, and the blood vessel pulse wave measurement result is obtained as the degree of arteriosclerosis or arterial age, for example. Can be displayed to the examiner.

  In the above description, the PC is used for the display C and the control unit D, but it goes without saying that the display of the automatic sphygmomanometer and the hardware of the control unit can be used as apparent from the above.

  Further, by comparing the amplitude of the pulse wave before stopping blood flow with the amplitude of the pulse wave after resuming blood flow, the degree of vascular tone of the subject E can be evaluated.

  In this embodiment, the pulse wave measurement is performed using the radial artery pressure measurement device P instead of the photoelectric fingertip volume pulse wave measurement device A in the first embodiment.

  In this embodiment, as shown in FIG. 4, the probe P1 (pressure sensor) of the radial artery pressure measuring device P is attached to the wrist of the subject E.

  The radial artery pressure measuring device P measures the pressure change of the radial artery at the wrist of the subject E via the probe P1, and the AC component signal (1) corresponding to the pulse wave and the DC component signal (2) corresponding to the average blood pressure. Is output.

  The display C and the control unit D are configured in the same manner as in the first embodiment. Under the control of the control unit D, the AC (pulse wave) component signal (1) and the DC (mean blood pressure) component signal (2) are displayed on the display C. indicate.

  The cuff pressure control device B and the cuff B1 are also configured in the same manner as in the first embodiment, but in this embodiment, the cuff B1 is attached to the upper arm of the subject E, presses the blood vessel by increasing or decreasing the air pressure, and stops the blood flow. Reopening is performed automatically. The cuff pressure signal (4) output from the control unit D to the cuff pressure control device B is also displayed on the display.

  After the measurement of the pulse wave of the subject E is started, the blood flow is stopped for a certain time by constricting the blood vessel by applying a cuff pressure. The stoppage of blood flow can be verified on the monitor display C as the disappearance of the pulse wave signal (1) and the decrease of the DC component (mean blood pressure) signal (2).

  Also in the present embodiment, blood flow is stopped by the cuff B1, and then the blood vessel pulse wave is measured by the radial artery pressure measuring device P.

  The blood flow stop time by the cuff B1 is set to a time when the increase in the amplitude of the pulse wave that occurs after the blood flow is resumed immediately after the cuff pressure is made zero.

  Regarding the control of the blood flow stop time by the cuff B1, the method described in the first embodiment can be used. In this example, the blood flow stop time was set to 1 minute (60 seconds).

  In the measurement, the pulse wave before the blood flow stoppage by the cuff B1 is input, and the five measured pulse waves are averaged to obtain an average waveform, and then the blood flow is stopped by the pressure of the cuff B1. An average waveform is obtained by averaging the five pulse waves measured at the time when the blood flow after resuming blood flow becomes maximum.

  FIG. 5 shows a typical pattern of the pulse wave signal (1) measured by the present embodiment. In FIG. 5, AI = P2 / P1 particularly represents the magnitude of the load applied to the heart and the aorta and can be used for evaluating the state of the blood vessel as being equivalent to the stiffness of the artery. The value of AI = P2 / P1 increases with arteriosclerosis and age.

  Here, Table 2 shows the vascular pulse wave measurement results obtained by applying various loads to the subject E in the apparatus of this example.

表２から明らかなように、喫煙、呼吸停止、過呼吸などにより、カフ加圧前のｂ／ａ値は大きく変動するのに対し、カフ圧開放後のｂ／ａ値は変動が少ないことがわかる。

As is apparent from Table 2, the b / a value before cuff pressurization greatly fluctuates due to smoking, respiratory arrest, hyperventilation, etc., whereas the b / a value after cuff pressure release is small. Recognize.

  Also in this example, when performing blood vessel pulse wave measurement, the cuff pressure is applied at the upstream portion of the measurement site to stop the blood flow for a predetermined time, and control to perform the pulse wave measurement after opening for various measurements. The blood vessel pulse wave can be measured with high accuracy without being influenced by the external factors, and the same effect as the above-described embodiment can be expected.

  The present invention essentially requires a cuff (manchette) capable of stopping blood flow. Therefore, as described above, the blood vessel pulse wave measurement function of the present invention is an optical probe (hardware) such as an automatic sphygmomanometer. 1) Alternatively, by adding a pressure probe (Embodiment 2), it can be implemented simply and inexpensively as an additional function of the product.

It is explanatory drawing which showed the structure of the vascular pulse wave measuring apparatus which employ | adopted this invention (Example 1). It is the wave form diagram which showed the acceleration pulse wave signal measured in the structure of FIG. FIG. 2 is a waveform diagram showing characteristics of a pulse wave signal measured in the configuration of FIG. 1. It is explanatory drawing which showed the different structure of the vascular pulse wave measuring apparatus which employ | adopted this invention (Example 2). FIG. 5 is a waveform diagram showing characteristics of a pulse wave signal measured in the configuration of FIG. 4.

Explanation of symbols

A Photoelectric fingertip volume pulse wave measurement device A1 Optical probe B Cuff pressure control device B1 Cuff C Display D Control unit P Radial artery pressure measurement device P1 Probe

Claims (3)

A pulse wave measuring means for measuring a blood vessel pulse wave of a peripheral blood vessel;
A blood flow stopping means for constricting a blood vessel upstream of the measurement site of the pulse wave measuring means to stop the blood flow;
A blood vessel pulse wave measuring apparatus comprising: a control unit that causes blood pulse measurement by the pulse wave measuring unit after the blood flow is stopped by the blood flow stopping unit for a predetermined time.   The vascular pulse wave measuring apparatus according to claim 1, wherein the pulse wave measuring unit measures an amplitude or a pulse pressure of the vascular pulse wave as information on the vascular pulse wave.   The blood flow stop time at which an increase in blood flow or an increase in pulse wave amplitude that occurs after the blood flow is stopped and resumed is used as the blood flow stop time by the blood flow stop means. Blood vessel pulse wave measuring device.

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