JP4680411B2 - Arterial blood pressure measuring method and arterial blood pressure measuring device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an arterial blood pressure measuring method and an arterial blood pressure measuring apparatus for measuring arterial blood pressure, and more particularly to an arterial blood pressure measuring method and an arterial blood pressure measuring apparatus for measuring in real time in a non-invasive manner.
[0002]
[Prior art]
As a non-invasive measurement of arterial blood pressure, currently, a deformable manchette is attached to the body part based on the Riva-rocci method, and when the pressure in the manchette is changed, that is, when the pressure is released from the manchette, Means are taken to correlate the two values of this pressure with systolic pressure and diastolic pressure. In this case, in order to correspond to the systolic pressure and the diastolic pressure, it is based on the blood vessel sound (Korotkoff sound) generated in the blood vessel by the blood when flowing through the artery. However, this method cannot measure arterial blood pressure in real time, for example, during exercise. Therefore, various sensor technologies have been applied to attempt a method for measuring arterial blood pressure non-invasively in real time. For example, in Japanese Patent Publication No. 2750023, sensor means is provided for radiating sound waves or light waves within the measurement range of a body including a single arterial blood vessel and receiving sound waves or light waves scattered from the blood of the artery. ing.
[0003]
[Problems to be solved by the invention]
By attaching these conventional sensors using sound waves and light waves to the body and observing changes in arterial blood pressure, it is possible to measure changes in arterial blood pressure in real time in a non-invasive manner. However, these measurement methods cannot directly measure pressure and measure changes in electrical signals such as voltage and frequency, so the unit representation differs depending on the type of sensor and measurement principle, and the Manchette method or directly in the artery. It is necessary to calibrate the pressure value obtained by the open blood method in which a pressure sensor is inserted (by invasiveness). Also, in order to measure in real time, these sensors are unstable to be fixed to the body as compared with the Manchette method, and there is a problem that the measurement data changes due to noise due to a slight movement of the body.
[0004]
An object of the present invention is to solve the problems of conventional non-invasive, real-time arterial blood pressure measurement methods and measurement devices, and to generate noise in measurement results by a sensor fixing method to a subject, regardless of the type of sensor. It is to provide a non-invasive, real-time arterial blood pressure measuring method and arterial blood pressure measuring device which prevent the above.
[0005]
[Means for Solving the Problems]
In the present invention, since the vibration amplitude of a substance is generally described by its frequency characteristics, the maximum blood pressure and the minimum blood pressure are also the amplitude and the pulse rate is the vibration frequency even in the vibration of a vascular system substance. Based on the viewpoint that it can be considered, the maximum and minimum arterial blood pressure can be expressed by a time function related to one cycle of the arterial waveform and the maximum and minimum values in that cycle. Based on the finding that FIG. 1 shows a period T of each cycle of an arterial waveform, from an arterial waveform obtained by a blood pressure method in which a pressure sensor is inserted (invasively) into an artery of a body to directly measure the intraarterial pressure. The time Ta from the lowest point to the maximum point in the one-beat arterial waveform, the time Tb obtained by subtracting Ta from the T, and the so-called one-minute pulse rate n obtained by converting the T into the vibration frequency per minute are obtained. The maximum blood pressure Ph which is the maximum value of the arterial waveform, the minimum blood pressure Pl which is the minimum value, and their relationship are shown. In FIG. 1A, between the value obtained by the product of the maximum blood pressure Ph and n and the product of Ta and Tb, in FIG. 1B, between the value obtained by dividing the square of n by the minimum blood pressure Pl and the square of Tb. Each has a strong relationship. That is, by selecting an appropriate function, the maximum blood pressure and the minimum blood pressure of the arterial blood pressure can be expressed by a time function related to one period of the arterial waveform and the maximum value and the minimum value in the one period.
[0006]
Therefore, the arterial blood pressure measuring method according to the present invention is an arterial waveform capturing step for capturing an arterial waveform obtained by an arterial waveform detection sensor attached to a test object in the blood pressure measuring method for measuring a maximum blood pressure and a minimum blood pressure of an artery. And using a zero-cross point of the arterial differential waveform for each beat , and one cycle of the arterial differential waveform in one beat The time T from the zero cross point corresponding to the minimum value of the arterial waveform to the zero cross point corresponding to the maximum value, the time Tb obtained by subtracting the Ta from the time T, and the above calculation. using the value of the obtained T, Ta and Tb, seek one minute pulse rate n by n = (60 / T), the maximum blood pressure Ph of each one heartbeat, a, and B constants, L G is as an indication of common logarithm, the {Ph * n = -A * LOG (Ta * Tb) -B} is calculated from the relational expression, diastolic blood pressure Pl of each one heartbeat, C, as a constant and D, { It has a blood pressure calculation step calculated from a relational expression of n * n / Pl = C * (Tb * Tb) ^−D }.
The arterial blood pressure measuring method according to the present invention is an arterial waveform capturing step for capturing an arterial waveform obtained by an arterial waveform detection sensor attached to a test object in the blood pressure measuring method for measuring a maximum blood pressure and a minimum blood pressure of an artery, A TATB calculation step for obtaining a time TA from the lowest value to the maximum value of the captured arterial waveform for each beat and a time TB obtained by subtracting the TA from a time T of one cycle of the arterial waveform in the one beat; Using the values of TA and TB obtained by the above calculation, the pulse rate n per minute is obtained by n = (60 / T), and A and B are constants, and LOG is a common logarithm for the maximum blood pressure Ph per beat. As shown , {n * n / Pl is calculated from a relational expression of {Ph * n = −A * LOG (TA * TB) −B} , and C and D are constants for the minimum blood pressure Pl for each beat. = C (TA * TB) - characterized by having a blood pressure calculation step of calculating the relational expression of ^D}.
[0009]
An arterial blood pressure measurement device according to the present invention is a blood pressure measurement device for measuring arterial maximum blood pressure and minimum blood pressure, sensor means for detecting an arterial waveform to be examined , and arterial waveform for taking in the arterial waveform obtained by the sensor means Using the capturing means, the arterial waveform differentiation calculating means for obtaining an arterial differential waveform by time-differentiating the captured arterial waveform for each beat, and using the zero cross point of the arterial differential waveform for each beat, Zero- cross to obtain a time T of one cycle of the arterial differential waveform at time T , a time Ta from a zero-cross point corresponding to the minimum value of the arterial waveform to a zero-cross point corresponding to the maximum value, and a time Tb obtained by subtracting Ta from the time T by using the operation means, the values of T and Ta and Tb obtained by the calculation to obtain the one minute pulse rate n by n = (60 / T), the maximum blood pressure Ph Nitsu per one heartbeat Te, A, B constants, LOG is as an indication of common logarithm, is calculated from the relational expression of Ph * n = -A * LOG ( Ta * Tb) -B}, the diastolic blood pressure Pl of each one heartbeat, C , D is a constant, and has a blood pressure calculation means for calculating from a relational expression of {n * n / Pl = C * (Tb * Tb) ^−D } .
[0011]
An arterial blood pressure measurement device according to the present invention is a blood pressure measurement device for measuring arterial maximum blood pressure and minimum blood pressure, sensor means for detecting an arterial waveform to be examined , and arterial waveform for taking in the arterial waveform obtained by the sensor means For the captured arterial waveform for each beat, the time TA from the minimum value to the maximum value, and the time TB obtained by subtracting the TA from the time T of one cycle of the arterial waveform in the single beat are obtained. TATB calculation means and TA and TB values obtained by the above calculation are used to obtain a pulse rate n per minute by n = (60 / T), and A and B are constants for the maximum blood pressure Ph for each beat. , LOG indicates the common logarithm, and is calculated from the relational expression {Ph * n = −A * LOG (TA * TB) −B} , and C and D are constants for the diastolic blood pressure Pl for each beat , {N n / Pl = C * (TB * TB) - characterized by having a blood pressure calculating means for calculating the relational expression of ^D}.
[0012]
An arterial blood pressure measuring method and an arterial blood pressure measuring device according to the present invention are provided with a sensor for detecting an arterial waveform in a test object, taking the arterial waveform from the sensor, obtaining the arterial differential waveform by time differentiation of the arterial waveform, The time Ti between zero-cross points in the arterial differential waveform for each beat and the time T of one cycle of the arterial differential waveform for that beat are obtained, and the values of Ti and T are preferably used at this time. Using a time Ta from the zero cross point corresponding to the lowest value to the zero cross point corresponding to the maximum value and a time Tb obtained by subtracting the Ta from the time T of one cycle of the arterial differential waveform at one beat. The function to calculate the maximum blood pressure and the minimum blood pressure is calculated, so that the time measurement can be performed stably regardless of the sensor type, and the arterial differential waveform is zero. By using the measurement of the loss point, preventing the generation of noise on the measurement results due to the method of fixing to the body of the sensor, thereby enabling more stable measurement.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 2 is a block diagram showing an embodiment of the present invention. In FIG. 2, the sensor 2 is attached to an appropriate part capable of detecting an arterial waveform on the body surface of the subject 1, for example, a wrist or an arm in the case of a human body. The terminal of the sensor 2 is connected to the arterial waveform capturing means 3, and further connected to the blood pressure calculating means 6 via the arterial waveform differential calculating means 4 and the zero cross calculating means 5, and the result is output. An example of such a sensor 2 is shown in FIG. Fig.3 (a) is sectional drawing at the time of using an infrared sensor as a sensor. In the infrared sensor 2, a light emitting element 12 having a diameter of about 3 mm and a light receiving element 13 having substantially the same size are arranged on a substrate. A cushion material 14 such as urethane is attached to the back surface of the substrate. FIG. 3B is a plan view thereof, in which four sets of two light emitting elements 12 arranged on both sides and one light receiving element 13 in the center are arranged. FIG. 3C uses the tactile sensor 2 as a sensor, and three piezoelectric conversion elements 15 are arranged on the substrate.
[0014]
The effect | action which concerns on the structure of FIG. 2 is demonstrated. A sensor 2 is attached to the body surface of the subject 1. Taking the sensor 2 shown in FIG. 3 as an example, in FIG. 3A, the infrared sensor 2 has a light-emitting element 12 and a light-receiving element 13 facing the subject 1 so that, for example, from above the cushion material 14 on the back surface. Then, press against the subject 1 with Velcro or an appropriate tape material and stop. When a current flows from the control circuit (not shown) of the infrared sensor 2 to the light emitting element 12, the light emitting element 12 is turned on. For example, infrared wavelength light is transmitted toward the artery 11 inside the subject 1, and the artery 11 is reflected while being influenced by arterial motion, that is, pulse wave, received by the light receiving element 13, and amplified by a control circuit (not shown). An arterial waveform can be obtained by the frequency change at this time. 3A, two light emitting elements 12 are arranged on both sides of one light receiving element 13, and four sets of such light emitting elements 12 and light receiving elements 13 are arranged in FIG. Can receive a wide range of arterial movements. It is the same consideration that three piezoelectric transducers 15 are attached to the tactile sensor 2 in FIG. Therefore, the number can be increased or decreased as necessary. In the upper part of FIG. 4, the waveform of the frequency change of the infrared sensor, and in the lower part, the pressure sensor is inserted into the artery of the subject 1 and the pressure in the artery is directly measured (open blood method). The comparison is shown by matching the time axis. As is clear from FIG. 4, the arterial waveform detected by the sensor 2 appropriately attached to the body surface shows a very good response except for the problem of the unit of the vertical axis. “Apart from the problem of the unit of the vertical axis” in this waveform means that the time axis of the horizontal axis is the same regardless of the sensor 2.
[0015]
The signal data detected by the sensor 2 is captured by the arterial waveform capturing means 3 and processed into continuous arterial waveform data. Next, the arterial waveform differential calculation means 4 calculates the arterial differential waveform of the captured arterial waveform. As such means, a general data acquisition system (DAS) and digital signal differentiation software can be used. FIG. 5A shows the arterial waveform obtained by the infrared sensor method, and FIG. 5B shows the arterial differential waveform. In both cases, the waveform is smoothed.
[0016]
Next, the zero cross calculation means 5 calculates the time Ti between the zero cross points for the arterial differential waveform and the time T of one cycle of the arterial differential waveform for each cycle of the arterial differential waveform. There can be a plurality of Ti. For example, referring to FIG. 5B, several zero cross points are recognized in one cycle of the arterial differential waveform. Among them, the zero-cross point corresponding to the two inflection points before and after the minimum blood pressure to the maximum blood pressure in FIG. 5 (a) is considered to be the most important, and then a little in the process of gradually reaching the minimum blood pressure from the maximum blood pressure. This is followed by a zero cross point corresponding to two inflection points in the period of increased blood pressure. Here, let Ta be the time between zero cross points corresponding to two inflection points before and after the lowest blood pressure considered to be the most important and the highest blood pressure. In addition, since Ta corresponds to the time TA from the lowest blood pressure point to the highest blood pressure point of the arterial waveform in FIG. 5A, it can be directly calculated from the arterial waveform. Also, a so-called one-minute pulse rate n obtained by converting one period T of the arterial differential waveform into a one-minute vibration frequency can be obtained by the following equation (1).
[Expression 1]
n = 60 / T (1)
However, the unit of T is sec.
[0017]
The blood pressure calculation means 6 calculates a function for obtaining the maximum blood pressure Ph and the minimum blood pressure Pl for each beat by using the plurality of Ti obtained by the zero cross calculation means 5 and one period T of the arterial differential waveform. An example of the function form is shown in FIG. FIG. 6 shows a function form obtained from three types of experimental results. The first experimental result shows that the maximum blood pressure Ph and the minimum blood pressure are obtained by a method of blood pressure in which a pressure sensor is inserted into an artery to directly obtain an arterial waveform. The above-described n, T, and Ta are calculated together with Pl, and Tb = T−Ta is calculated, which is the data itself of FIG. In the second experiment, an infrared sensor is attached to an appropriate site where pulsation of arterial blood pressure on the human body surface can be detected, and the above-mentioned n, T, Ta, and Tb are obtained from the arterial waveform observed by the infrared sensor, At the same time, the maximum blood pressure and the minimum blood pressure were measured by the Manchette method, and the third experiment was performed in the same manner as the second experiment using a tactile sensor instead of the infrared sensor. In FIG. 6, the first experimental result is distinguished by a black circle, the second experimental result by a white circle, and the third experimental result by a triangular mark. From the result of FIG. 6A, the maximum blood pressure Ph for each beat is expressed by Expression (2), and from the result of FIG. 6B, the minimum blood pressure Pl for each beat is expressed by Expression (3).
[Expression 2]
Ph * n = −A * LOG (Ta * Tb) −B (2)
However, A and B are constants, Tb = T-Ta, and LOG indicates a common logarithm.
[Equation 3]
n * n / Pl = C * ( Tb * Tb) ^−D (3)
However, C and D are constants.
The results calculated according to the equations (2) and (3) are displayed as the maximum blood pressure Ph and the minimum blood pressure Pl of the arterial waveform for each beat.
[0018]
Moreover, it can be seen from the results of FIG. 6 that the arterial blood pressure measurement method and the arterial blood pressure measurement device according to the present invention can stably measure regardless of the type of sensor. That is, in FIG. 6, there is no significant difference between the result when the LED is used as the sensor and the result when the tactile sensor is used, and the two methods of the Manchette method and the open blood method are used. Can also use one arithmetic expression. This indicates that the arterial blood pressure measurement method and the arterial blood pressure measurement device according to the present invention are time measurement methods, so that there is no difference between the sensor of the infrared sensor method and the tactile sensor method, and measurement can be performed extremely stably. .
[0019]
FIG. 6 shows the application results of the function forms represented by the mathematical expressions (2) and (3) using the most prominent Ta and Tb among Ti. This is because the three points of the minimum blood pressure point, the maximum blood pressure point, and the minimum blood pressure point are set as one cycle as an approximation. By selecting an appropriate Ti, the function forms of the second and third approximations are used. The present invention can be implemented. In addition, various models of arterial waveforms can be derived from consideration of amplitude values and frequency characteristics of vibration characteristics of vascular substances. However, even in this case, the present invention is implemented as long as it is a functional form including T and Ti. it can. That is, even in the variation of the arterial waveform model, the function of T, Ti that does not depend on the output value (vertical axis) of the arterial waveform determined by the type of sensor is calculated using the zero-cross point of the arterial differential waveform, and the model Therefore, the present invention can be implemented by representing the maximum blood pressure and the minimum blood pressure.
[0020]
【The invention's effect】
An arterial blood pressure measuring method and an arterial blood pressure measuring device according to the present invention are provided with a sensor for detecting an arterial waveform in a test object, taking the arterial waveform from the sensor, obtaining the arterial differential waveform by time differentiation of the arterial waveform, The time Ti between zero-cross points in the arterial differential waveform for each beat and the time T of one cycle of the arterial differential waveform for that beat are obtained, and the values of Ti and T are preferably used at this time. Using a time Ta from the zero cross point corresponding to the lowest value to the zero cross point corresponding to the maximum value and a time Tb obtained by subtracting the Ta from the time T of one cycle of the arterial differential waveform at one beat. Since the function for calculating the maximum blood pressure and the minimum blood pressure is calculated, stable measurement can be performed regardless of the type of sensor. In addition, the measurement of the zero-cross point of the arterial differential waveform can be used to prevent the generation of noise in the measurement result due to the method of fixing the sensor to the body, and more stable measurement is possible.
[Brief description of the drawings]
FIG. 1 is a diagram showing the relationship between Ta and Tb of arterial waveform of open blood method and the maximum blood pressure and minimum blood pressure, which is the knowledge of the present invention.
FIG. 2 is a block diagram showing an embodiment of an arterial blood pressure measurement device according to the present invention.
FIG. 3 is an example of a sensor according to an embodiment of the present invention. (A) is sectional drawing of an infrared sensor, (b) is the top view, (c) is a figure which shows a tactile sensor.
FIG. 4 is a diagram showing a waveform of the frequency change of the infrared sensor (upper stage) and a pressure waveform (lower stage) by the blood-opening method.
5A shows an arterial waveform obtained by an infrared sensor method, and FIG. 5B shows an arterial differential waveform in the embodiment of the arterial blood pressure measuring device according to the present invention.
FIG. 6 is a diagram showing various experimental results and function forms derived therefrom in the embodiment of the arterial blood pressure measurement device according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Subject, 2 Sensor, 3 Arterial waveform acquisition means, 4 Arterial waveform differentiation calculating means, 5 Zero cross calculating means, 6 Blood pressure calculating means, 11 Arteries, 12 Light emitting element, 13 Light receiving element, 14 Cushion material, 15 Piezoelectric conversion element, Ph Maximum blood pressure, Pl diastolic blood pressure, time of one cycle of T arterial waveform, Ta time between zero crossing point corresponding to maximal blood pressure point, time of Tb T-Ta, each of zero crossing in Ti arterial differential waveform Time between points, n 1 minute pulse rate.

Claims (4)

In the blood pressure measurement method for measuring the maximum blood pressure and the minimum blood pressure of the artery,
An arterial waveform capturing step for capturing an arterial waveform obtained by an arterial waveform detection sensor attached to a test object;
Arterial waveform differentiation calculation step of obtaining the arterial differential waveform by time differentiation of the captured arterial waveform,
Using the zero-cross point of the arterial differential waveform for each beat, the period T of one cycle of the arterial differential waveform in that beat and the zero-cross point corresponding to the minimum value of the arterial waveform to the zero-cross point corresponding to the maximum value A zero cross operation step for obtaining a time Ta and a time Tb obtained by subtracting the Ta from the time T ;
Using the values of T, Ta, and Tb obtained by the above calculation,
Obtain the pulse rate n per minute by n = (60 / T),
With respect to the maximum blood pressure Ph for each beat , A and B are constants, LOG is a common logarithm, and is calculated from the relational expression {Ph * n = −A * LOG (Ta * Tb) −B},
An arterial characterized by having a blood pressure calculation step for calculating a minimum blood pressure Pl for each beat from a relational expression {n * n / Pl = C * (Tb * Tb) ^−D } , where C and D are constants. Blood pressure measurement method. In the blood pressure measurement method for measuring the maximum blood pressure and the minimum blood pressure of the artery,
An arterial waveform capturing step for capturing an arterial waveform obtained by an arterial waveform detection sensor attached to a test object;
A TATB calculation step for obtaining a time TA from the lowest value to the maximum value of the captured arterial waveform for each beat and a time TB obtained by subtracting the TA from a time T of one cycle of the arterial waveform in one beat; ,
Using the values of TA and TB obtained by the above calculation,
Obtain the pulse rate n per minute by n = (60 / T),
With respect to the maximum blood pressure Ph for each beat, A and B are constants, LOG is a common logarithm, and is calculated from the relational expression {Ph * n = −A * LOG (TA * TB) −B},
For diastolic blood pressure Pl of each one heartbeat, C, as a constant and D, - and wherein Rukoto to have a blood pressure calculation step of calculating the relational expression of {n * n / Pl = C * (TB * TB) D} To measure arterial blood pressure. In a blood pressure measurement device that measures the maximum and minimum blood pressure of arteries,
Sensor means for detecting an arterial waveform to be examined;
And arterial waveform capture means for capturing the resulting arterial waveform by said sensor means,
Arterial waveform differentiation calculation means for obtaining an arterial differential waveform by differentiating the arterial waveform for each captured beat with respect to time,
Using the zero-cross point of the arterial differential waveform for each beat, the period T of one cycle of the arterial differential waveform in that beat and the zero-cross point corresponding to the minimum value of the arterial waveform to the zero-cross point corresponding to the maximum value Zero cross calculation means for obtaining a time Ta and a time Tb obtained by subtracting Ta from the time T ;
Using the values of T, Ta, and Tb obtained by the above calculation,
Obtain the pulse rate n per minute by n = (60 / T),
With respect to the maximum blood pressure Ph for each beat , A and B are constants, LOG is a common logarithm, and is calculated from the relational expression {Ph * n = −A * LOG (Ta * Tb) −B},
An artery having a blood pressure calculating means for calculating a minimum blood pressure Pl for each beat from a relational expression {n * n / Pl = C * (Tb * Tb) ^−D } with C and D as constants Blood pressure measurement device . In a blood pressure measurement device that measures the maximum and minimum blood pressure of arteries,
Sensor means for detecting an arterial waveform to be examined;
Arterial waveform capturing means for capturing the arterial waveform obtained by the sensor means ;
The arterial waveform for each one-heartbeat captured before SL, TATB calculating means for calculating the time TA to a maximum value from the minimum value, the time TB minus the TA from a period of time T of the arterial waveform at its one beat When,
Using the values of TA and TB obtained by the above calculation,
Obtain the pulse rate n per minute by n = (60 / T),
With respect to the maximum blood pressure Ph for each beat , A and B are constants, LOG is a common logarithm, and is calculated from the relational expression {Ph * n = −A * LOG (TA * TB) −B},
An artery having a blood pressure calculating means for calculating a minimum blood pressure Pl for each beat from a relational expression {n * n / Pl = C * (TB * TB) ^−D } , where C and D are constants. Blood pressure measurement device.

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