JP2011136018A - Pulse wave analysis apparatus and pulse wave analysis program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pulse wave analysis apparatus capable of suppressing inaccuracy in detecting pulse waves caused by the nonlinearity of the change of the pressure/volume of blood vessels, and more accurately acquiring the amplitude of an ejection waves and a reflection wave of the pulse waves. <P>SOLUTION: In the pulse wave analysis apparatus, a pressure control part 8 of a vascular internal/external pressure difference control part 2 controls the difference between the internal pressure and external pressure in the blood vessels in one region so that the amplitude of the pulse waves detected by a pulse wave amplitude information detecting part 7 is in a range in which the relation with the difference between the internal pressure and external pressure in the one region detected by a pulse wave detecting part 1 can be considered approximately as linear by controlling the external pressure applied to the blood vessels in the one region detected by the pulse wave detection part 1. As a result, the variation in the amplitude of the pulse waves relative to the variation of the internal pressure of the blood vessels can be linear and large, and the amplitude of the ejection wave and reflection wave of the pulse waves can be more accurately detected by a pulse wave amplitude detection part 6. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a pulse wave analysis device and a pulse wave analysis program for accurately identifying ejection waves and reflected waves contained in a pulse wave of a living body.

  It is known that the pulse wave has various important information for grasping the state of the circulatory system of a living body. For example, AI (Augmentation Index) is used for quantitative evaluation of the degree of arteriosclerosis in the whole body, estimation of central arterial pressure, etc. by calculating the ratio of the ejection wave component and the reflected wave component contained in the pulse wave. It is used.

  In order to obtain the AI, it is necessary to specify each of the ejection wave component and the reflected wave component included in the pulse wave, and a technique for that purpose is disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 2004-313468) and the like. Has been. In Patent Document 1, the ejection wave component and the reflected wave component are obtained by waveform analysis based on the differentiation of the pulse wave.

  In addition, regarding the pulse wave velocity obtained by measuring the pulse wave at two measurement sites, the ejection wave and the reflected wave are separated, and the time difference between the ejection wave and the reflected wave is used to determine the velocity at one measurement site. Japanese Patent Laid-Open No. 2003-010139 discloses a technique for identifying the pulse wave velocity from the pulse wave.

  By the way, as a method for detecting a pulse wave, there is a volume pulse wave method for detecting a volume change of a blood vessel due to a wave, and a photoelectric volume pulse wave using light is generally used. This method can be constituted by an LED (light emitting diode) and a PD (photodiode), and a pulse wave detection system can be constructed at a relatively low cost.

  Further, the blood vessel has a three-layer structure of an inner membrane, a middle membrane, and an outer membrane, and it is known that the elastic characteristics of the blood vessel change depending on the pressure acting on the blood vessel. That is, the pressure-volume characteristic of the blood vessel shows a strong non-linearity and does not show a volume change proportional to the pressure change. For example, as shown in Patent Document 3, a method for modeling a pressure-volume characteristic of a blood vessel with a sigmoid curve is disclosed.

  By the way, as described above, Patent Literature 1 and Patent Literature 2 disclose a technique for separating ejection waves and reflected waves. In particular, Patent Literature 1 classifies the waveforms of pulse waves to obtain respective waveforms. A technique is disclosed in which the ejection wave and the reflected wave can be appropriately separated by performing appropriate waveform analysis.

  However, even in the plethysmogram, even if the temporal positional relationship within one pulse wave can be correctly identified for each of the ejection wave and the reflected wave, the non-linearity of the pressure-volume change of the blood vessel When comparing the amplitudes of the ejection wave and the reflected wave, it cannot be accurately compared.

JP 2004-313468 A JP 2003-10139 A JP 2008-228934 A

  Therefore, an object of the present invention is to suppress the inaccuracy of pulse wave detection caused by the nonlinearity of the pressure-volume change of the blood vessel and to obtain the amplitude of the pulse wave and the reflected wave with higher accuracy. An object is to provide a pulse wave analysis device and a pulse wave analysis program capable of performing the above.

In order to solve the above problems, a pulse wave analysis device according to the present invention includes a pulse wave detection unit that detects a pulse wave in a certain part of a living body,
An area in which the amplitude of the pulse wave is detected from the pulse wave at the partial position detected by the pulse wave detection unit, and the relationship of the amplitude of the pulse wave with respect to the difference between the internal pressure and the external pressure of the partial blood vessel is approximately linear Intravascular / external pressure difference control unit that controls the difference between the internal pressure and the external pressure of the partial blood vessels so as to enter,
A reference for detecting a reference time for specifying the ejection wave component included in the pulse wave at the partial position detected by the pulse wave detection unit and a reference time for specifying the reflected wave component included in the pulse wave A time detector;
The amplitude of the pulse wave corresponding to the reference time of the ejection wave component detected by the reference time detection unit is detected and the pulse wave corresponding to the reference time of the reflected wave component detected by the reference time detection unit is detected. And a pulse wave amplitude detector for detecting the amplitude.

  According to the pulse wave analyzing apparatus of the present invention, the intravascular / external pressure difference control unit is configured to enter the region in which the relationship of the amplitude of the pulse wave with respect to the difference between the internal pressure and the external pressure of the partial blood vessels can be regarded as substantially linear. The difference between the internal pressure and the external pressure of the blood vessel at one site is adjusted. As a result, the change in the amplitude of the pulse wave with respect to the change in the internal pressure of the blood vessel can be linearly increased, and the amplitude of the ejection wave and the reflected wave of the pulse wave can be detected with higher accuracy by the pulse wave amplitude detection unit. it can.

  Further, in the pulse wave analysis device of one embodiment, the region in which the relationship of the amplitude of the pulse wave with respect to the difference between the internal pressure and the external pressure of the partial blood vessel is substantially linear is the internal pressure and the external pressure of the partial blood vessel. A region in which the change in the amplitude of the pulse wave with respect to the change in the difference is maximum is included.

  According to the pulse wave analysis device of this embodiment, the intravascular / external pressure difference control unit includes a region where the change in the amplitude of the pulse wave is maximized with respect to the change in the difference between the internal pressure and the external pressure of the partial blood vessels. In addition, the difference between the internal pressure and the external pressure of the partial blood vessel is adjusted so that the relationship of the amplitude of the pulse wave with respect to the difference between the internal pressure and the external pressure of the partial blood vessel is in a substantially linear region. Thereby, the change of the amplitude of the pulse wave with respect to the change of the internal pressure of the blood vessel can be maximized, and the amplitude of the ejection wave and the reflected wave of the pulse wave can be detected with higher accuracy by the pulse wave amplitude detection unit. .

In the pulse wave analysis device of one embodiment, the information indicating the amplitude of the pulse wave obtained from the internal / external pressure difference control unit by changing the difference between the internal pressure and the external pressure of the blood vessel by the internal / external pressure difference control unit and the blood vessel A blood pressure-volume change characteristic modeling unit for obtaining in advance the pressure-volume change characteristic of the blood vessel based on information representing the difference between the internal pressure and the external pressure of
The pulse wave amplitude detector is
The blood pressure-volume change characteristic obtained by the blood vessel pressure-volume change characteristic modeling unit, information indicating the difference between the internal pressure and the external pressure of the blood vessel from the internal / external pressure difference control unit, and the pulse wave detection unit Based on the detected pulse wave, the amplitude of the pulse wave corresponding to the reference time is obtained.

  According to the pulse wave analysis device of this embodiment, the blood vessel pressure-volume change characteristic modeling unit is configured to output the blood vessel based on the information indicating the amplitude of the pulse wave and the information indicating the difference between the internal pressure and the external pressure of the blood vessel. The pressure-volume change characteristic of is determined in advance. Therefore, the pulse wave amplitude detection unit includes information representing a difference between the pulse wave detected by the pulse wave detection unit, the pressure-volume change characteristic of the blood vessel, and the internal pressure and external pressure of the blood vessel from the internal / external pressure difference control unit. Based on the above, the amplitude of the pulse wave corresponding to the reference time can be obtained more accurately.

  In the pulse wave analysis device of one embodiment, the internal / external pressure difference control unit controls the internal pressure of the blood vessel by controlling the internal pressure of the blood vessel by controlling the height of the pulse wave detection unit with respect to the heart of the living body. Controls the difference from external pressure.

  According to the pulse wave analysis device of this embodiment, the internal / external pressure difference control unit controls the internal pressure of the blood vessel by controlling the height of the pulse wave detection unit with respect to the heart of the living body, and the internal pressure of the blood vessel. The difference from the external pressure can be controlled.

  In the pulse wave analysis device according to an embodiment, the internal / external pressure difference control unit controls the difference between the internal pressure and the external pressure of the blood vessel by controlling the external pressure applied to the blood vessel by the pulse wave detection unit.

  According to the pulse wave analysis device of this embodiment, the internal / external pressure difference control unit can control the difference between the internal pressure and the external pressure of the blood vessel by controlling the external pressure applied to the blood vessel by the pulse wave detection unit.

In the pulse wave analysis program of one embodiment, the amplitude of the pulse wave is detected from the pulse wave at a certain part of the living body, and the pulse wave is detected with respect to the change in the difference between the internal pressure and the external pressure of the blood vessel at the part. Intravascular / external pressure difference control function for controlling the difference between the internal pressure and the external pressure of the blood vessels in the above-mentioned part of the region where the change in amplitude can be regarded as linear,
A reference time deriving function for obtaining a reference time for specifying the ejection wave component included in the pulse wave at the partial position and a reference time for specifying the reflected wave component included in the pulse wave;
A computer is caused to execute a pulse wave amplitude deriving function for obtaining an amplitude of the pulse wave corresponding to the reference time of the ejection wave component and obtaining an amplitude of the pulse wave corresponding to the reference time of the reflected wave component.

  According to the pulse wave analysis program of this embodiment, the relationship between the amplitude of the pulse wave with respect to the difference between the internal pressure and the external pressure of the partial blood vessels falls within a region where the difference can be regarded as substantially linear by the intravascular external pressure difference control function. The difference between the internal pressure and the external pressure of the partial blood vessels is adjusted. Thereby, the change of the amplitude of the pulse wave with respect to the change of the internal pressure of the blood vessel can be maximized, and the amplitude of the pulse wave ejected wave and the reflected wave can be detected with higher accuracy by the pulse wave amplitude deriving function. .

  Further, in the pulse wave analysis program of one embodiment, the region in which the relationship of the amplitude of the pulse wave with respect to the difference between the internal pressure and the external pressure of the partial blood vessel is substantially linear is the internal pressure and the external pressure of the partial blood vessel. A region in which the change in the amplitude of the pulse wave with respect to the change in the difference is maximum is included.

  According to the pulse wave analysis program of this embodiment, the intravascular external pressure difference control function includes a region in which the change in the amplitude of the pulse wave with respect to the change in the difference between the internal pressure and the external pressure of the partial blood vessels is maximized. At the same time, the difference between the internal pressure and the external pressure of the partial blood vessel is adjusted so that the relationship of the amplitude of the pulse wave with respect to the change in the difference between the internal pressure and the external pressure of the partial blood vessel falls within a substantially linear range. Thereby, the change of the amplitude of the pulse wave with respect to the change of the internal pressure of the blood vessel can be maximized, and the amplitude of the pulse wave and the reflected wave can be detected with higher accuracy by the pulse wave amplitude detection function. .

In the pulse wave analysis program of one embodiment, the information indicating the amplitude of the pulse wave obtained from the internal / external pressure difference control function by changing the difference between the internal pressure and the external pressure of the blood vessel by the internal / external pressure difference control function and the blood vessel Based on the information representing the difference between the internal pressure and the external pressure of the blood vessel, the computer executes a blood vessel pressure-volume change characteristic modeling function for obtaining the blood pressure-volume change characteristic in advance,
Information indicating the difference between the blood pressure-volume change characteristic of the blood vessel obtained by the blood vessel pressure-volume change characteristic modeling function and the internal pressure and the external pressure of the blood vessel from the internal / external pressure difference control function by the pulse wave amplitude derivation function Based on the above, the pulse wave amplitude corresponding to the reference time is obtained.

  According to the pulse wave analysis program of this embodiment, based on the information indicating the amplitude of the pulse wave and the information indicating the difference between the internal pressure and the external pressure of the blood vessel by the blood vessel pressure-volume change characteristic modeling function, The pressure-volume change characteristic of the blood vessel is obtained in advance, and the pulse wave amplitude detection function is used to detect the pulse wave and information indicating the difference between the blood pressure-volume change characteristic of the blood vessel and the internal / external pressure from the internal / external pressure difference control unit. Based on the pulse wave detected by the unit, the amplitude of the pulse wave corresponding to the reference time can be obtained more accurately.

In the pulse wave analysis program of one embodiment, the internal / external pressure difference control function is
The difference between the internal pressure and the external pressure of the blood vessel is controlled by controlling the internal pressure of the blood vessel by controlling the height of the biological wave with respect to the heart of the living body by detecting the pulse wave at a certain part of the living body. .

  According to the pulse wave analysis program of this embodiment, the internal / external pressure difference control function controls the internal pressure of the blood vessel by controlling the height of the pulse wave detector with respect to the heart of the living body to The difference from the external pressure can be controlled.

In the pulse wave analysis program of one embodiment, the internal / external pressure difference control function is
The difference between the internal pressure and the external pressure of the blood vessel is controlled by controlling the external pressure with respect to the blood vessel of the partial position by the pulse wave detection unit that detects the pulse wave at a certain partial position of the living body.

  According to the pulse wave analysis program of this embodiment, the difference between the internal pressure and the external pressure of the blood vessel can be controlled by controlling the external pressure of the pulse wave detecting unit with respect to the blood vessel by the internal / external pressure difference control function.

  According to the pulse wave analysis apparatus of the present invention, the intravascular / external pressure difference control unit enters a region in which the relationship of the amplitude of the pulse wave to the difference between the internal pressure and the external pressure of a certain partial blood vessel of the living body can be regarded as substantially linear. The difference between the internal pressure and the external pressure of the partial blood vessels is adjusted. Thereby, the change in the amplitude of the pulse wave with respect to the change in the internal pressure of the blood vessel can be linearly increased, and the amplitude of the pulse wave ejection wave and the reflected wave can be detected with higher accuracy by the pulse wave amplitude detector.

1 is a block diagram showing a first embodiment of a pulse wave analysis device of the present invention. FIG. 4 is a waveform diagram showing a pulse wave waveform detected by the pulse wave detection unit of the embodiment in a column (A) and an acceleration waveform of the pulse wave in a column (B). It is a wave form diagram which shows the 3rd derivative waveform of the pulse wave detected by the above-mentioned pulse wave detection part in the (A) column, and shows the 4th derivative waveform of the above-mentioned pulse wave in the (B) column. It is a waveform diagram showing the pulse wave amplitude and pulse wave amplitudes W1 and W2 at the reference points Q1 and Q2 of the pulse wave. It is a characteristic view which shows the relationship between the difference of the internal pressure of a blood vessel, and an external pressure, and the blood vessel volume. 7 is a graph illustrating pressure P and pulse wave amplitude W applied to a portion where the pulse wave is measured by the pressure control unit 8 when searching for a pulse wave amplitude maximum point. It is a block diagram which shows 2nd Embodiment of the pulse-wave analyzer of this invention. It is a block diagram which shows 3rd Embodiment of the pulse-wave analyzer of this invention. It is a schematic diagram explaining the internal pressure control part of the said 2nd Embodiment. It is a flowchart explaining the operation | movement which searches the point where the pulse wave amplitude becomes the maximum by the intravascular external pressure difference control part of the said 1st Embodiment. It is a graph for demonstrating the process in which the vascular pressure-volume change characteristic modeling part 29 produces the said blood pressure-volume change characteristic in the said 2nd Embodiment. It is a graph which shows the relationship between the internal / external pressure difference (mmHg) and the amplitude per 1 mmHg (V / mmHg) for demonstrating the said process. It is a graph for demonstrating the process in which the said pulse wave amplitude detection part 26 detects the pulse wave amplitude in the reference time T2 of a reflected wave component in the said 2nd Embodiment. It is a figure which shows typically a pulse wave waveform for demonstrating the said process.

  Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

(First embodiment)
FIG. 1 is a block diagram of a first embodiment of the pulse wave analysis apparatus of the present invention. The pulse wave analysis device 10 of the first embodiment includes a pulse wave detection unit 1 that detects a pulse wave in a certain part of a human living body, an intravascular external pressure difference control unit 2, and ejection wave / reflected wave characteristic information. And an extraction unit 3.

  As the pulse wave detection unit 1, for example, a device using a photoelectric volume pulse wave method in which the degree of reflection or absorption of infrared light output from a light emitting element according to the blood volume in a blood vessel is measured by a light receiving element is used. There is. In addition, the body part for measuring the pulse wave by the pulse wave detector 1 is not particularly limited, but is preferably a non-invasive / non-constrained part. -Wrist and earlobe are preferred.

  The ejection wave / reflected wave feature information extraction unit 3 includes a reference time detection unit 5 and a pulse wave amplitude detection unit 6. The reference time detection unit 5 specifies a reference time for specifying the ejection wave component included in the pulse wave at the partial position detected by the pulse wave detection unit 1 and the reflected wave component included in the pulse wave. And a reference time for detecting. The detection of the reference time will be described later. The pulse wave amplitude detector 6 detects the amplitude of the pulse wave corresponding to the reference time of the ejection wave component detected by the reference time detector 5 and detects the amplitude detected by the reference time detector 5. The amplitude of the pulse wave corresponding to the reference time of the reflected wave component is detected.

  The intravascular / external pressure difference control unit 2 includes a pulse wave amplitude information detection unit 7 that detects the amplitude of the pulse wave from the pulse wave at the partial position detected by the pulse wave detection unit 1, and the internal pressure of the partial blood vessel. A pressure control unit 8 for controlling a difference from the external pressure. The pressure control unit 8 is configured so that the pulse wave amplitude detected by the pulse wave amplitude information detection unit 7 falls within a region where the relationship between the difference between the internal pressure and the external pressure of the partial blood vessels can be regarded as substantially linear. The difference between the internal pressure and the external pressure of the blood vessel at the site is controlled. A method for controlling the difference between the internal pressure and the external pressure of the partial blood vessels will be described later.

  In the pulse wave analyzing apparatus 10 having the above configuration, an example of a process in which the reference time detection unit 5 obtains the reference time will be described below.

  First, an example of a pulse wave waveform detected by the pulse wave detector 1 is shown in the (A) column of FIG. 2A. The vertical axis in the column (A) of FIG. 2A represents the measured voltage value (V) corresponding to the pressure (mmHg) corresponding to the amplitude of the pulse wave. In the pulse wave propagation velocity measuring apparatus 10 of this embodiment, as an example, the voltage value (V) measured by the pulse wave detector 1 with the blood pressure (mmHg) measured by a general cuff sphygmomanometer is the pulse wave. Correction (calibration) of how to correspond to the pressure (mmHg) corresponding to the amplitude of. As will be described later, this correction (calibration) is performed by the pressure controller 8 at a site where the intravascular pressure difference controller 2 controls the pressure controller 8 and the pulse wave detector 1 measures the pulse wave. It may be performed after the external pressure to be applied is set so as to be close to the internal pressure of the blood vessel in the region, and the result of the calibration may be used in the subsequent measurement.

  For example, when the pulse wave is Type C of the blood pressure waveform classification by Murgo et al., The reference time detection unit 5 is the time of the systolic maximum point Q1 in the pulse wave waveform shown in the (A) column of FIG. 2A. T1 is detected as the reference time T1 of the ejection wave component. The (B) column of FIG. 2A shows the acceleration wave of the pulse wave, and the (A) column of FIG. 2B shows the triple differential wave of the pulse wave. For example, when the pulse wave is Type C of blood pressure waveform classification by Murgo et al., The reference time detection unit 5 performs the third zero cross of the fourth-order differential wave of the pulse wave shown in the (B) column of FIG. 2B. The point Q2 is detected as the reference time T2 of the reflected wave component. The third zero-cross point Q2 means a point at which the fourth differential waveform shown in FIG. 2B (B) zero-crosses downward for the third time after the pulse wave shown in FIG. 2A (A) has reached the minimum value. To do.

  In the above description, the case where the detected pulse wave is Type C of the blood pressure waveform classification has been described. However, when the detected pulse wave has a waveform shape other than Type C of the blood pressure waveform classification, If there is a method that can suitably specify the reference time of the ejection wave component of the pulse wave and the reference time of the reflected wave component, it may be adopted. For example, if the pulse wave does not show a large blood pressure fluctuation, it basically does not show a very large waveform change, so by superimposing a plurality of measured pulse waves (addition averaging), the pulse wave detection accuracy can be improved. It becomes possible to plan.

  In addition, since the pulse wave shows various waveform shapes depending on the noise level, age, sex, presence / absence of disease, physical condition, etc., the reference time of the ejection wave component of the pulse wave and the reflected wave component are more preferably If there is a method that can specify the reference time, it may be adopted. For example, it is possible to improve the accuracy of specifying the reference time of the ejection wave component of the pulse wave and the reference time of the reflected wave component by leaving the detected pulse wave as a history together with the state of the measurement subject at that time. .

  Further, the pulse wave amplitude detector 6 included in the pulse wave analyzer 10 corresponds to the reference time T1 of the ejection wave component detected by the reference time detector 5 as illustrated in the waveform diagram of FIG. The amplitude W1 of the pulse wave S is detected, and the amplitude W2 of the pulse wave S corresponding to the reference time T2 of the reflected wave component detected by the reference time detector 5 is detected. In this way, a method for obtaining the amplitudes W1 and W2 of the pulse wave S corresponding to the reference time T1 and T2 of the ejection wave component and the reflected wave component of the pulse wave S has recently been used as a diagnostic index for the circulatory system. It is a technique adopted in the AI (Augmentation Index).

  Further, in this pulse wave analysis device 10, the pressure control unit 8 included in the intravascular / external pressure difference control unit 2 converts the amplitude of the pulse wave detected by the pulse wave amplitude information detection unit 7 into the internal pressure and the external pressure of the partial blood vessels. An example of a method for controlling the difference between the internal pressure and the external pressure of the partial blood vessels so as to fall within a region where the relationship with the difference can be regarded as substantially linear will be described below.

  FIG. 4 is a characteristic diagram showing the relationship between the difference between the internal pressure and the external pressure of the blood vessel and the blood vessel volume. As shown in FIG. 4, the relationship between the difference between the internal pressure and the external pressure of the blood vessel and the blood vessel volume is a non-linear relationship as a whole. The external pressure is a pressure applied to the blood vessel by the pulse wave detector 1.

  In FIG. 4, for example, region (a) corresponds to the case where the external pressure is weak and the external pressure is smaller than the internal pressure, and region (c) corresponds to the case where the external pressure is strong and the external pressure is greater than the internal pressure. Yes. The region (b) corresponds to the case where the external pressure and the internal pressure are close to each other as compared with the regions (a) and (c). Moreover, the dashed-dotted line shown with the code | symbol J has shown the case where an external pressure and an internal pressure are equal.

  In the region (a) in FIG. 4 where the external pressure is weak, it can be seen that the change in volume of the blood vessel exhibits nonlinear characteristics with respect to the change in internal pressure applied to the blood vessel. Further, even in the region (c) in FIG. 4 where the external pressure is strong, the change in the volume of the blood vessel exhibits nonlinear characteristics with respect to the change in the internal pressure applied to the blood vessel. The region (c) where the external pressure is large is a region where the blood vessel is almost crushed and the volume of the blood vessel hardly changes.

  On the other hand, in the region (b) of FIG. 4, the difference between the external pressure and the internal pressure is small, and when this internal / external pressure difference is around 0 mmHg, the change in blood vessel volume with respect to the change in internal pressure is the largest. That is, this region (b) is a region where the blood vessel is soft. Further, when the internal / external pressure difference is around 0 mmHg, it can be assumed that the volume change with respect to the pressure change is almost linear. Therefore, by adjusting in advance the external pressure applied by the pressure control unit 8 to the part where the pulse wave detecting unit 1 measures the pulse wave, and setting the external pressure close to the internal pressure of the blood vessel, The relationship between the difference between the internal pressure and the external pressure and the blood vessel volume can be placed in a region that can be regarded as being substantially linear as shown in region (b) of FIG.

  For example, as described below with reference to the flowchart of FIG. 9, the pressure (external pressure) applied to the portion for measuring the pulse wave by the pressure control unit 8 is changed, and the pulse wave amplitude information detection unit 7 is changed. To search for a point where the pulse wave amplitude is maximum. Further, FIG. 5 illustrates a waveform indicating the pressure (external pressure) P applied to the portion where the pulse wave is measured by the pressure control unit 8 and the pulse wave amplitude W during the search. In addition, as a method of changing the external pressure by the pressure control unit 8, the cuff pressure is controlled as in the oscillometric method conventionally used for measuring the blood pressure value.

  First, in step S1 shown in the flowchart of FIG. 9, the initial pressure applied to the blood vessel by the pressure control unit 8 is set. Next, in step S2, the pulse wave is detected from the pulse wave detected by the pulse wave detection unit 1 at the initial pressure. The amplitude information detector 7 calculates amplitude information. Next, in step S3, the intravascular / external pressure difference control unit 2 records the amplitude information and the external pressure information. Next, in step S4, the pressure control unit 8 increases the external pressure applied to the blood vessel by a predetermined value. Next, in step S5, the intravascular / external pressure difference control unit 2 records amplitude information and external pressure information on the increased external pressure. Next, in step S6, the intravascular external pressure difference control unit 2 determines whether or not the pulse wave amplitude based on the current pulse wave information from the pulse wave detection unit 1 is smaller than the pulse wave amplitude based on the previous pulse wave information. If it is determined that it is small, the process proceeds to the next step S7, and if it is not small, the process returns to step S4. In step S7, the external pressure applied to the part where the pressure control unit 8 measures the pulse wave is set to a pressure value corresponding to the previous pulse wave amplitude.

  In this way, the pressure control unit 8 maintains the pressure (external pressure) applied to the pulse wave measurement site at the point where the pulse wave amplitude is maximized, and thus the pressure-volume change characteristic is shown in the region (b) of FIG. It is possible to set a linear region as shown in FIG. By setting the pressure-volume change characteristic in this linear region (b), the ratio of the amplitude of the ejected wave such as AI and the reflected wave can be accurately detected. Is possible.

  As described above, the intravascular / external pressure difference control unit 2 detects the amplitude of the pulse wave from the pulse wave at a certain partial position of the living body, and the pulse with respect to the difference between the internal pressure and the external pressure of the partial blood vessel is detected. An intravascular / external pressure difference control function for controlling the difference between the internal pressure and the external pressure of the partial blood vessels so that the relationship of wave amplitudes can be regarded as substantially linear, and the reference time detection unit 5 includes the reference times T1 and T2 And a pulse wave amplitude deriving function in which the pulse wave amplitude detection unit 6 obtains the amplitudes W1 and W2 of the pulse wave S corresponding to the reference times T1 and T2 is executed by a computer using a pulse wave analysis program. You may let them.

(Second embodiment)
FIG. 6 is a block diagram of a second embodiment of the pulse wave analyzer of the present invention. The pulse wave analysis device 20 according to the second embodiment includes a pulse wave detection unit 21 that detects a pulse wave in a certain part of a human body, an intravascular external pressure difference control unit 22, and ejection wave / reflected wave characteristic information. An extraction unit 23 and a vascular pressure-volume change characteristic modeling unit 29 are provided. The pulse wave detection unit 21 included in the pulse wave analysis device 20 of the second embodiment has the same configuration as the pulse wave detection unit 1 included in the first embodiment.

  In addition, the intravascular external pressure difference control unit 22 included in the pulse wave analysis device 20 of the second embodiment detects pulse wave amplitude information from the pulse wave at the partial position detected by the pulse wave detection unit 21. It has a detection unit 27 and an internal pressure control unit 28 that controls the internal pressure of the blood vessel by controlling the height of the pulse wave detection unit 21 with respect to the heart of the living body.

For example, as shown in FIG. 8, the internal pressure control unit 28 controls the height h of the living body heart 81 with respect to the living body heart 81 by moving the pulse wave detection unit 21 attached to the living body arm 80 up and down with an elevating device 83. I can do it. The internal pressure control unit 28 changes the intravascular pressure using the hydrostatic pressure change caused by changing the height h of the pulse wave detection unit 21 with respect to the heart 81 by the lifting device 83. Note that pulse pressure = (maximum blood pressure−minimum blood pressure) and average blood pressure (minimum blood pressure + pulse pressure / 3) are calculated from the maximum blood pressure and minimum blood pressure obtained in advance. The internal pressure is changed based on the calculated average blood pressure and pulse pressure information.
Although the height is controlled using an elevating device as the internal pressure control unit, if there is a method that can control and detect the height more suitably, it may be adopted. For example, an acceleration sensor is mounted on the pulse wave detector, and the height of the heart can be estimated from the arm length and the output value of the acceleration sensor.

Then, the vascular pressure-volume change characteristic modeling unit 29 obtains information representing the height h from the heart 81 of the pulse wave detection unit 21 from the internal pressure control unit 28, and from the change amount Δh of the height, The internal pressure change amount ΔPin of the blood vessel is calculated by the following equation (1).
ΔPin = ρ × g × Δh (1)

In the above equation (1),
ΔPin: change in internal pressure of blood vessel ρ: density of blood g: acceleration of gravity Δh: change in height from the heart to the measurement site.

  In this embodiment, since the external pressure (pressure applied by the pulse wave detection unit 21 to the blood vessel) is a constant value, the internal pressure change calculated by the blood vessel pressure-volume change characteristic modeling unit 29 using the above equation (1). The amount ΔPin is the amount of change in the intravascular / external pressure difference.

  Therefore, the vascular pressure-volume change characteristic modeling unit 29 changes the intravascular external pressure difference and the pulse wave amplitude change detected by the pulse wave amplitude information detection unit 27 corresponding to the intravascular external pressure difference. From the above information, a relational characteristic between the change amount of the intravascular external pressure difference and the change amount of the pulse wave amplitude is created. Then, the vascular pressure-volume change characteristic modeling unit 29 creates the pressure-volume change characteristic of the blood vessel from the relational characteristic between the change amount of the intravascular external pressure difference and the change amount of the pulse wave amplitude.

Here, a process in which the vascular pressure-volume change characteristic modeling unit 29 obtains the vascular pressure-volume change characteristic from the relational characteristic between the change amount of the intravascular external pressure difference and the change amount of the pulse wave amplitude will be described. .
As shown in FIG. 10, the pulse wave amplitude (V) as a difference from the measured value (V) of the pulse wave waveform at each internal pressure change amount Pv (ΔPin) to the minimum value of the pulse wave is obtained. Ask. Next, the pulse wave amplitude (V) is divided by the previously obtained pulse pressure = (maximum blood pressure−minimum blood pressure). Thereby, the amplitude (V / mmHg) per 1 mmHg in a certain internal / external pressure difference (mmHg) is obtained.
When the relationship between the internal / external pressure difference (mmHg) thus obtained and the amplitude per 1 mmHg (V / mmHg) is graphed, the graph shown in FIG. 11 is obtained. The graph of FIG. 11 is a graph obtained by differentiating the model expression of the pressure-volume change characteristic of the blood vessel. For example, the following equation (3) is obtained by differentiating a model equation based on a sigmoid function as shown in the following equation (2). Then, the coefficients A, α, and β are obtained by performing curve fitting on the graph shown in FIG. 11 with the following equation (3). As a result, the coefficients A, α, and β of the model equation (2) of the blood pressure-volume change characteristic are derived. In the following equation (2), P is the internal / external pressure difference (mmHg), and V (P) is a signal value corresponding to the blood vessel volume.
V (P) = A / (1 + exp (α · P + β)) (2)
dV / dP = Aαexp (α · P + β) / (1 + exp (α · P + β)) ² (3)

  The information of the model expression (2) of the pressure-volume change characteristic specified by the vascular pressure-volume characteristic modeling unit 29 is obtained from the vascular pressure-volume characteristic modeling unit 29 by the ejection wave / reflected wave characteristic information. This is input to the pulse wave amplitude detector 26 of the extractor 23.

  In the ejected wave / reflected wave feature information extraction unit 23, the reference time detection unit 25 performs the pulse wave detection by the pulse wave detection unit 21 in the same manner as the reference time detection unit 5 of the first embodiment described above. The reference time T1 of the ejection wave component and the reference time T2 of the reflected wave component are detected. The pulse wave amplitude detector 26 receives a pressure signal representing a pressure corresponding to the amplitude of the pulse wave detected by the pulse wave detector 21. The pulse wave amplitude detector 26 calculates the intravascular external pressure difference P from the pressure represented by the pressure signal at the reference time T1 of the ejection wave component of the pulse wave. Further, the pulse wave amplitude detection unit 26 sets the pulse wave amplitude value at the reference time T1 of the ejection wave component as the pulse pressure (maximum blood pressure−minimum blood pressure). As described above, this pulse wave amplitude value is calibrated to correspond to a pressure signal based on blood pressure (mmHg) measured in advance with a general cuff sphygmomanometer.

Further, the pulse wave amplitude detector 26 uses the expression (2) as the pressure-volume change characteristic to reflect the pressure represented by the pressure signal at the reference time T2 of the reflected wave component of the pulse wave. The pulse wave amplitude at the reference time T2 of the wave component is detected.
Here, referring to FIGS. 12 and 13, the pulse wave amplitude detection unit 26 uses the model expression (2) of the blood pressure-volume change characteristic by the sigmoid function to calculate the reflected wave component reference time. The process of deriving the pulse wave amplitude value at T2 will be described.
(i) First, an internal / external pressure difference (Pmax−Pex) is obtained by subtracting an external pressure Pex applied to a measurement site from a pre-obtained maximum blood pressure value Pmax. Next, the internal / external pressure difference (Pmax−Pex) is substituted as the internal / external pressure difference P (mmHg) into the model equation (2) of the blood pressure-volume change characteristic obtained by the pressure-volume change characteristic modeling unit 29. Thus, a signal value Vf corresponding to the blood vessel volume is obtained (see FIG. 12).
(ii) Next, as shown in FIG. 13, a value obtained by subtracting the measured voltage value mr of the reflected wave component from the measured voltage value mf of the ejected wave component obtained from the ejected wave / reflected wave feature information extraction unit 23. ms (= mf−mr) is obtained. The measured voltage value mr of the reflected wave component corresponds to the pulse wave amplitude detected by the pulse wave detector 21 at the reference time T2. The measured voltage value mf of the ejection wave component corresponds to the pulse wave amplitude detected by the pulse wave detector 21 at the reference time T1.
(iii) Next, the difference measurement value ms obtained in the previous item (ii) is subtracted from the signal value Vf corresponding to the blood vessel volume obtained from the model equation (2) of the blood pressure-volume change characteristic in the previous item (i). The subtraction value (Vf−ms) is substituted into V (P) of the model equation (2) of the blood pressure-volume change characteristic to obtain the internal / external pressure difference Ptmr. Finally, by subtracting the minimum blood pressure from this internal / external pressure difference Ptmr, it is possible to determine how many mmHg of blood pressure the reflected wave amplitude corresponds to.

  Thus, according to the pulse wave analysis device 20 of the second embodiment, the pulse wave amplitude detection unit 26 is a model of the pulse wave detected by the pulse wave detection unit 21 and the pressure-volume change characteristic of the blood vessel. Based on the pressure-volume change characteristic of the blood vessel as expressed by the equation (2), the amplitude of the pulse wave corresponding to each of the reference times T1 and T2 can be obtained more accurately.

  The intravascular / external pressure difference control function corresponding to the intravascular / external pressure difference control unit 22 and the vascular pressure / volume change characteristic modeling function corresponding to the vascular pressure / volume change characteristic modeling unit 29 are computerized by a pulse wave analysis program. May be executed.

(Third embodiment)
FIG. 7 is a block diagram of a third embodiment of the pulse wave analyzer of the present invention. The pulse wave analysis device 70 according to the third embodiment includes a pulse wave detection unit 71 that detects a pulse wave in a certain part of a human body, an intravascular external pressure difference control unit 72, and ejection wave / reflected wave characteristic information. An extraction unit 73 and a vascular pressure-volume change characteristic modeling unit 75 are provided. The pulse wave detection unit 71 included in the pulse wave analysis device 70 of the third embodiment has the same configuration as the pulse wave detection unit 1 included in the first embodiment.

  Further, the intravascular external pressure difference control unit 72 included in the third embodiment includes a pulse wave amplitude information detection unit 77 that detects the amplitude of the pulse wave from the pulse wave at the partial position detected by the pulse wave detection unit 71, and the above A pressure control unit 78 for controlling the difference between the internal pressure and the external pressure of the blood vessel at one site. The pressure control unit 78 has the same configuration as the pressure control unit 8 of the first embodiment described above. Therefore, the pressure control unit 78 uses the pulse wave amplitude detected by the pulse wave amplitude information detection unit 77 in the same way as the pressure control unit 8 of the first embodiment described above to determine the internal pressure and external pressure of the partial blood vessels. The difference between the internal pressure and the external pressure of the partial blood vessels is controlled such that the relationship with the difference is within a region that can be regarded as substantially linear.

  In the third embodiment, the pressure controller 78 gradually increases the pressure applied to the blood vessel by the pulse wave detector 71 under the control of the pulse wave amplitude information detector 77. As a result, the pressure control unit 78 pressurizes the intra-vascular external pressure difference to a region where the blood vessel collapses (region where the pulse wave amplitude is minimized). During this pressurization period, the intravascular / external pressure difference control unit 72 measures the intravascular / external pressure difference and the corresponding pulse wave amplitude.

The pressure control unit 78 changes the external pressure applied to the blood vessel measurement site by, for example, changing the cuff pressure applied to the blood vessel measurement site. The value of the external pressure can be detected by using the cuff control value. Then, the intravascular / external pressure difference control unit 72 calculates the intravascular / external pressure difference by subtracting the value of the external pressure detected using the cuff control value from the previously calculated blood pressure value. The blood pressure value calculated in advance is a blood pressure value (mmHg) measured in advance with a general cuff sphygmomanometer, as described above.
Here, a process in which the vascular pressure-volume change characteristic modeling unit 75 obtains the vascular pressure-volume change characteristic from the relational characteristic between the change amount of the intravascular external pressure difference and the change amount of the pulse wave amplitude will be described. .
The vascular pressure-volume change characteristic modeling unit 75 calculates the pulse wave amplitude (mV) as a difference from the measured voltage value (V) of the pulse wave waveform at each external pressure change amount to the maximum value to the minimum value of the pulse wave. ) Next, the pulse wave amplitude (mV) is divided by the previously obtained pulse pressure = (maximum blood pressure−minimum blood pressure). Thereby, the amplitude (V / mmHg) per 1 mmHg in a certain internal / external pressure difference (mmHg) is obtained.
When the relationship between the internal / external pressure difference (mmHg) thus obtained and the amplitude per 1 mmHg (V / mmHg) is graphed, a graph as shown in FIG. 11 similar to that described in the second embodiment is obtained. The graph of FIG. 11 is a graph obtained by differentiating the model expression of the pressure-volume change characteristic of the blood vessel. For example, the following equation (3) is obtained by differentiating a model equation based on a sigmoid function as shown in the following equation (2). Then, the coefficients A, α, and β are obtained by performing curve fitting on the graph shown in FIG. 11 with the following equation (3). As a result, the coefficients A, α, and β of the model equation (2) of the blood pressure-volume change characteristic are derived. In the following equation (2), P is the internal / external pressure difference (mmHg), and V (P) is a signal value corresponding to the blood vessel volume.
V (P) = A / (1 + exp (α · P + β)) (2)
dV / dP = Aαexp (α · P + β) / (1 + exp (α · P + β)) ² (3)

  The information of the pressure-volume change characteristic model equation (2) obtained by the pressure-volume characteristic modeling unit 75 is sent from the pressure-volume characteristic modeling unit 75 to the ejection wave / reflected wave characteristic information extraction unit. 73 is input to the pulse wave amplitude detector 79.

  In the ejected wave / reflected wave feature information extraction unit 73, the reference time detection unit 76 performs the pulse wave detection by the pulse wave detection unit 1 in the same manner as the reference time detection unit 5 of the first embodiment described above. The reference time T1 of the ejection wave component and the reference time T2 of the reflected wave component are detected. The pulse wave amplitude detector 79 receives a pressure signal representing a pressure corresponding to the amplitude of the pulse wave detected by the pulse wave detector 71. The pulse wave amplitude detector 79 calculates the intra-vascular external pressure difference P from the pressure represented by the pressure signal at the reference time T1 of the ejection wave component of the pulse wave. Further, the pulse wave amplitude detection unit 79 sets the pulse wave amplitude value at the reference time T1 of the ejection wave component as the pulse pressure (maximum blood pressure−minimum blood pressure). As described above, this pulse wave amplitude value is calibrated to correspond to a pressure signal based on blood pressure (mmHg) measured in advance with a general cuff sphygmomanometer.

  Further, the pulse wave amplitude detector 79 uses the model equation (2) of the pressure-volume change characteristic to express the pressure represented by the pressure signal at the reference time T2 of the reflected wave component of the pulse wave. The pulse wave amplitude at the component reference time T2 is detected. The process in which the pulse wave amplitude detecting unit 79 derives the pulse wave amplitude value at the reflected wave component reference time T2 using the model equation (2) of the blood pressure-volume change characteristic by the sigmoid function is as follows: The second embodiment described above is the same as that described with reference to FIGS.

  Thus, according to the pulse wave analysis device 70 of the third embodiment, the pulse wave amplitude detection unit 79 is a model equation for the pulse wave detected by the pulse wave detection unit 71 and the pressure-volume change characteristic ( Based on the pressure-volume change characteristic of the blood vessel as represented by 2), the amplitude of the pulse wave corresponding to each of the reference times T1 and T2 can be obtained more accurately.

  The intravascular / external pressure difference control function corresponding to the intravascular / external pressure difference control unit 72 and the vascular pressure / volume change characteristic modeling function corresponding to the vascular pressure / volume change characteristic modeling unit 75 are computerized by a pulse wave analysis program. May be executed. In the second and third embodiments, the sigmoid function shown in the following equation (2) is adopted as the model of the pressure-volume change characteristic. Of course, the present invention is not limited to the sigmoid function, and other desirable desired model formulas can be adopted.

  The pulse wave analysis device of the present invention is suitable for an application where it is required to identify the ejection wave and the reflected wave included in the pulse wave of a living body with high accuracy. This is useful for obtaining new biometric indices. As an example, by calculating the ratio of the ejection wave component and the reflected wave component contained in the pulse wave, the AI (used for quantitative evaluation of the degree of arteriosclerosis in the whole body, estimation of central arterial pressure, etc. (Augmentation Index) can also be used to obtain a biological index useful for grasping the state of the living body.

1, 21, 71 Pulse wave detection unit 2, 22, 72 Intravascular / external pressure difference control unit 3, 23, 73 Ejection wave / reflected wave feature information extraction unit 5, 25, 75 Reference time detection unit 6, 26, 79 Pulse wave Amplitude detectors 7, 27, 77 Pulse wave amplitude information detectors 8, 78 Pressure controller 10, 20, 70 Pulse wave analyzer 28 Intravascular pressure controller

Claims (10)

A pulse wave detector for detecting a pulse wave in a certain part of the living body;
An area in which the amplitude of the pulse wave is detected from the pulse wave at the partial position detected by the pulse wave detection unit, and the relationship of the amplitude of the pulse wave with respect to the difference between the internal pressure and the external pressure of the partial blood vessel is approximately linear Intravascular / external pressure difference control unit that controls the difference between the internal pressure and the external pressure of the partial blood vessels so as to enter,
A reference for detecting a reference time for specifying the ejection wave component included in the pulse wave at the partial position detected by the pulse wave detection unit and a reference time for specifying the reflected wave component included in the pulse wave A time detector;
The amplitude of the pulse wave corresponding to the reference time of the ejection wave component detected by the reference time detection unit is detected and the pulse wave corresponding to the reference time of the reflected wave component detected by the reference time detection unit is detected. A pulse wave analysis device comprising: a pulse wave amplitude detection unit for detecting an amplitude. In the pulse wave analysis device according to claim 1,
The region in which the relationship of the amplitude of the pulse wave with respect to the difference between the internal pressure and the external pressure of the partial blood vessel can be regarded as substantially linear is the change in the amplitude of the pulse wave with respect to the change in the difference between the internal pressure and the external pressure of the partial blood vessel. A pulse wave analysis device characterized by including a region where the maximum is. In the pulse wave analysis device according to claim 1 or 2,
Information indicating the amplitude of the pulse wave obtained from the internal / external pressure difference control unit by changing the difference between the internal pressure and the external pressure of the blood vessel by the internal / external pressure difference control unit and information indicating the difference between the internal pressure and the external pressure of the blood vessel Based on the vascular pressure-volume change characteristic modeling unit for obtaining the blood pressure-volume change characteristic in advance,
The pulse wave amplitude detector is
The pulse wave detected by the pulse wave detection unit, the blood pressure-volume change characteristic of the blood vessel obtained by the blood vessel pressure-volume change characteristic modeling unit, and the internal pressure and external pressure of the blood vessel from the internal / external pressure difference control unit A pulse wave analysis device characterized in that an amplitude of a pulse wave corresponding to the reference time is obtained based on information representing a difference. In the pulse wave analysis device according to any one of claims 1 to 3,
The internal / external pressure difference control unit
A pulse wave analyzing apparatus characterized by controlling a difference between an internal pressure and an external pressure of the blood vessel by controlling a height of the pulse wave detecting unit with respect to the heart of the living body to control an internal pressure of the blood vessel. In the pulse wave analysis device according to any one of claims 1 to 3,
The internal / external pressure difference control unit
A pulse wave analysis device that controls a difference between an internal pressure and an external pressure of the blood vessel by controlling an external pressure applied to the blood vessel by the pulse wave detection unit. The amplitude of this pulse wave is detected from the pulse wave at a certain part of the living body, and the relation of the amplitude of the pulse wave with respect to the difference between the internal pressure and the external pressure of the blood vessel at the part of the living body is in a region that can be regarded as substantially linear. Intravascular / external pressure difference control function for controlling the difference between the internal pressure and external pressure of a blood vessel in one site,
A reference time deriving function for obtaining a reference time for specifying the ejection wave component included in the pulse wave at the partial position and a reference time for specifying the reflected wave component included in the pulse wave;
A pulse wave amplitude deriving function for obtaining the amplitude of the pulse wave corresponding to the reference time of the ejection wave component and obtaining the amplitude of the pulse wave corresponding to the reference time of the reflected wave component is executed by a computer. A pulse wave analysis program. In the pulse wave analysis program according to claim 6,
The region in which the relationship of the amplitude of the pulse wave with respect to the difference between the internal pressure and the external pressure of the partial blood vessel can be regarded as substantially linear is the change in the amplitude of the pulse wave with respect to the change in the difference between the internal pressure and the external pressure of the partial blood vessel. A pulse wave analysis program characterized by including a region in which is maximized. In the pulse wave analysis program according to claim 6 or 7,
Information indicating the amplitude of the pulse wave obtained from the internal / external pressure difference control function by changing the difference between the internal pressure and the external pressure of the blood vessel by the internal / external pressure difference control function and information indicating the difference between the internal pressure and the external pressure of the blood vessel Based on the above, the computer is caused to execute a blood pressure-volume change characteristic modeling function for obtaining the blood pressure-volume change characteristic in advance,
Information indicating the difference between the blood pressure-volume change characteristic of the blood vessel obtained by the blood vessel pressure-volume change characteristic modeling function and the internal pressure and the external pressure of the blood vessel from the internal / external pressure difference control function by the pulse wave amplitude derivation function Based on the above, the pulse wave analysis program for obtaining the amplitude of the pulse wave corresponding to the reference time. In the pulse wave analysis program according to any one of claims 6 to 8,
The internal / external pressure difference control function
The difference between the internal pressure and the external pressure of the blood vessel is controlled by controlling the internal pressure of the blood vessel by controlling the height of the biological wave with respect to the heart of the living body by detecting the pulse wave at a certain part of the living body. A pulse wave analysis program characterized by that. In the pulse wave analysis program according to any one of claims 6 to 8,
The internal / external pressure difference control function
A pulse wave analysis characterized by controlling a difference between an internal pressure and an external pressure of the blood vessel by controlling an external pressure with respect to the blood vessel of the partial position by a pulse wave detection unit that detects a pulse wave at a certain partial position of the living body. program.

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