Vascular endothelial function evaluation system, vascular endothelial function evaluation device, and vascular endothelial function evaluation method

Abstract

The pulse wave measurement unit generates a pulse wave signal on the basis of the measurement result of a pulse wave sensor attached to a site farther from the heart than a site to be pressurized for expelling blood. The peripheral blood pressure index calculation unit calculates a peripheral blood pressure index relating to the gradient of the rise of each beat of the pulse wave signal generated by the pulse wave measurement unit. The vascular endothelial function evaluation unit evaluates the vascular endothelial function on the basis of the calculated value of the peripheral blood pressure index from the point in time at which the expulsive blood has been released until the evaluation time elapses.

Description

Technical Field

[0001] The invention relates to a vascular endothelial function evaluation system, a vascular endothelial function evaluation device and a vascular endothelial function evaluation method. Background Art

[0002] Endothelial cells are used for contraction and relaxation of the vascular wall, adhesion of inflammatory cells to the vascular wall, regulation of vascular permeability, coagulation and fibrinolysis system, etc. These functions of endothelial cells (endothelial function) are reduced due to various lifestyle diseases such as hypertension, diabetes, dyslipidemia, obesity, etc. As evaluation methods for endothelial function, flow-dependent vasodilator response test (FMD), EndoPAT test, etc. are known.

[0003] In addition, a device for evaluating endothelial function using a cuff-type sphygmomanometer is known (Patent Document 1). In this evaluation device, endothelial function is evaluated based on a pulse wave detected by a pressure sensor connected to the cuff of the cuff-type sphygmomanometer in any two intervals before, during, and after pressurization stimulation.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2013-126487 Summary of the invention

[0007] Problem that the invention aims to solve

[0008] The existing endothelial function evaluation device (Patent Document 1) uses the pulse wave obtained by the pressure sensor connected to the cuff to evaluate the endothelial function. The pulse wave obtained by the pressure sensor mainly obtains information about thick blood vessels, but cannot obtain information about thin blood vessels such as arterioles and capillaries.

[0009] An object of the present invention is to provide a vascular endothelial function evaluation system, a vascular endothelial function evaluation device, and a vascular endothelial function evaluation method capable of evaluating the vascular endothelial function including arterioles and capillaries.

[0010] Solutions for solving problems

[0011] According to one aspect of the present invention, there is provided a vascular endothelial function evaluation system comprising:

[0012] a pulse wave measuring unit that generates a pulse wave signal based on a measurement result of a pulse wave sensor installed at a site farther from the heart than a pressurized site to be pressurized for blood removal;

[0013] Output section;

[0014] a peripheral blood pressure index calculation unit that calculates a peripheral blood pressure index related to the steepness of the rise per beat of the pulse wave signal generated by the pulse wave measurement unit; and

[0015] The vascular endothelial function evaluation unit evaluates the vascular endothelial function based on the calculated value of the peripheral blood pressure index from the time point when the blood drainage is released to the time when the evaluation time elapses.

[0016] According to another aspect of the present invention, there is provided a vascular endothelial function evaluation device comprising:

[0017] a pulse wave measuring device that generates a pulse wave signal based on a measurement result of a pulse wave sensor installed at a site farther from the heart than a pressurized site to be pressurized for blood removal; and

[0018] A control terminal calculates a peripheral blood pressure index related to the steepness of the rise of each beat of the pulse wave signal generated by the pulse wave measuring device, evaluates the vascular endothelial function based on the calculated value of the peripheral blood pressure index from the time point when the expulsion blood is released to the time when the evaluation time has passed, and outputs the evaluation result.

[0019] According to another aspect of the present invention, a method for evaluating vascular endothelial function is provided, which comprises the following steps:

[0020] A part of the body is pressurized to drive blood, and then released, and a pulse wave signal of an artery or capillary is obtained from a certain time from the time when the blood is released at a part farther from the heart than the pressurized part;

[0021] Calculating the time variation of the peripheral blood pressure index related to the rising steepness of each beat of the acquired pulse wave signal; and

[0022] The vascular endothelial function is evaluated based on the temporal changes in the peripheral blood pressure index.

[0023] Effects of the Invention

[0024] The peripheral blood pressure index includes blood flow information of peripheral blood vessels such as arterioles and capillaries. The endothelial function is evaluated based on the calculated value of the peripheral blood pressure index from the time of blood drainage to the time of evaluation. Therefore, the endothelial function including the information of peripheral blood vessels can be evaluated. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a block diagram of the vascular endothelial function evaluation system of the first embodiment.

[0026] Figure 2A This is a three-dimensional diagram of a pulse wave measuring device. Figure 2B This is a schematic diagram of a photoelectric pulse wave sensor and biological tissue when the pulse wave measurement device is worn on a finger.

[0027] Figure 3 1 is a flowchart showing the process of the vascular endothelial function evaluation method according to the first embodiment.

[0028] Figure 4 This is a graph showing an example of a pulse wave, a velocity pulse wave, and an acceleration pulse wave.

[0029] Figure 5 This is a graph showing an example of a pulse wave and an accelerated pulse wave.

[0030] Fig. 6A and Figure 6B This is a graph showing the relationship between the value of the peripheral blood pressure index "1 / VE0.5" obtained from the pulse wave measured when the height from the heart to the measured part (finger) is changed, and when the height of the measured part is made consistent with the chest and the vicinity of the elbow on the side where the finger, which is the measured part, is located is cooled, and the systolic blood pressure measured at the wrist.

[0031] Fig. 7A and Figure 7B This is a graph showing the relationship between the value of the peripheral blood pressure index "a / S" obtained from the pulse wave measured when the height from the heart to the measured part (finger) is changed, and when the height of the measured part is made consistent with the chest and the vicinity of the elbow on the side where the finger, which is the measured part, is located is cooled, and the systolic blood pressure measured at the wrist.

[0032] Fig. 8A and Figure 8B This is a graph showing the relationship between the value of the peripheral blood pressure indicator "(ab) / (ad)" obtained from the pulse wave measured when the height from the heart to the measured part (finger) is changed, and when the height of the measured part is made consistent with the chest and the vicinity of the elbow on the side where the finger, which is the measured part, is located is cooled, and the systolic blood pressure measured at the wrist.

[0033] Fig. 9 is a graph showing a pulse wave acquired from a subject A whose blood pressure is within a normal range.

[0034] FIG. 10A to FIG. 10F The figure shows that according to Fig. 9 The graph shown is a graph of the time change of the peripheral blood pressure index obtained from the pulse wave.

[0035] Fig.11is a graph showing the pulse wave acquired from another test subject B whose blood pressure is within the normal range.

[0036] FIG. 12A to FIG. 12F The figure shows that according to Fig.11 The graph shown is a graph of the time change of the peripheral blood pressure index obtained from the pulse wave.

[0037] Fig.13 is a graph showing a pulse wave acquired from a subject C whose blood pressure is outside the normal range.

[0038] Fig.14A , Fig. 14B as well as Fig. 14C It shows that according to Fig.13 The graph shown is a graph of the time change of the peripheral blood pressure index obtained from the pulse wave.

[0039] Fig.15 It shows that the Fig. 9 The pulse wave shown is a graph of the pulse wave of subject A measured in such a way that the blood drainage time is prolonged.

[0040] FIG. 16A to FIG. 16F The figure shows that according to Fig.15 The graph shown is a graph of the time change of the peripheral blood pressure index obtained from the pulse wave.

[0041] Fig.17 : is a flowchart showing the process of the vascular endothelial function evaluation method according to the second embodiment.

[0042] Fig.18 : is a flowchart showing the procedure of the vascular endothelial function evaluation method according to the modification of the second embodiment.

[0043] Fig.19A and Fig.19B It shows that according to Fig.15 The amplitude S( Figure 5 ) and a graph of the time changes of the peripheral blood pressure index "a / S".

[0044] Fig. 20 It is a block diagram of the vascular endothelial function evaluation system according to the fourth embodiment.

[0045] Fig.21 This is a schematic diagram of a user wearing a measurement device when evaluating vascular endothelial function using the vascular endothelial function evaluation system of the fourth embodiment. DETAILED DESCRIPTION

[0046] [First embodiment]

[0047] Reference Figures 1 to 14C The accompanying drawings illustrate the vascular endothelial function evaluation system and vascular endothelial function evaluation method of the first embodiment.

[0048] Figure 1 : is a block diagram of the vascular endothelial function evaluation system of the first embodiment. The vascular endothelial function evaluation system of the first embodiment includes a pulse wave measurement device 20, a control terminal 30, a server 40, and a cuff-type blood pressure meter 50. The pulse wave measurement device 20 includes a communication unit 24, the control terminal 30 includes a communication unit 33, the server 40 includes a communication unit 44, and the cuff-type blood pressure meter 50 includes a communication unit 55. The pulse wave measurement device 20, the control terminal 30, the server 40, and the cuff-type blood pressure meter 50 mutually communicate data via these communication units. For example, in the communication between the pulse wave measurement device 20 and the control terminal 30, and in the communication between the cuff-type blood pressure meter 50 and the control terminal 30, wireless communication based on a short-range wireless communication standard such as Bluetooth (registered trademark) is used. In the communication between the control terminal 30 and the server 40, a wireless LAN or the like is used.

[0049] The pulse wave measurement device 20 includes a photoelectric pulse wave sensor 21, a light emission control unit 22, a pulse wave measurement unit 23, and a communication unit 24. The photoelectric pulse wave sensor 21 includes a light emitting element and a light receiving element. The light receiving element receives light output from the light emitting element and passes through the biological tissue, and measures the intensity of the received light. The light emission control unit 22 controls the light emission of the light emitting element. The pulse wave measurement unit 23 generates a pulse wave signal based on the measured value of the intensity of the light from the photoelectric pulse wave sensor 21.

[0050] The control terminal 30 includes a control unit 31, an output unit 32, and a communication unit 33. As the control terminal 30, for example, a smartphone can be used. By installing an application in the smartphone, the smartphone can be used as the control terminal 30.

[0051] The control unit 31 receives the pulse wave signal from the pulse wave measurement device 20, and transmits the received pulse wave signal to the server 40. The control unit 31 also receives the evaluation result of the vascular endothelial function from the server 40, and outputs the evaluation result to the output unit 32. The output unit 32 includes, for example, a display device for displaying an image. The evaluation result of the vascular endothelial function is displayed on the display device in the form of an image or text.

[0052] The server 40 includes a pulse wave feature quantity calculation unit 41, a peripheral blood pressure index calculation unit 42, a vascular endothelial function evaluation unit 43, and a communication unit 44. The pulse wave feature quantity calculation unit 41 calculates various feature quantities of the waveform of the pulse wave signal received from the control terminal 30 (hereinafter, sometimes simply referred to as "pulse wave"). The peripheral blood pressure index calculation unit 42 calculates a peripheral blood pressure index related to the steepness of the rise of the pulse wave for each beat based on the feature quantity of the pulse wave. The peripheral blood pressure index can be used as an index indicating the magnitude of the peripheral blood pressure. For the peripheral blood pressure index, refer to Figures 4 to 8B The accompanying drawings are described in detail.

[0053] The vascular endothelial function evaluation unit 43 evaluates the vascular endothelial function based on the temporal change of the peripheral blood pressure index, and transmits the evaluation result to the control terminal 30. The vascular endothelial function evaluation unit 43 also stores the evaluation result.

[0054] The cuff-type sphygmomanometer 50 includes a pressurizing unit 51, a pulse detecting unit 52, a control unit 53, a blood pressure calculating unit 54, and a communication unit 55. As the cuff-type sphygmomanometer 50, for example, a cuff-type automatic electronic sphygmomanometer can be used. The control unit 53 receives instructions from the control terminal 30 to perform pressurization control of the pressurizing unit 51. The pressurizing unit 51 includes a cuff. By wrapping the cuff around the user's upper arm and performing pressurization control, blood expulsion can be started and released. The pulse detecting unit 52 detects the pulse of the part around which the cuff is wrapped. The blood pressure calculating unit 54 calculates the blood pressure based on the pressure applied to the cuff and the detection result of the pulse detecting unit 52.

[0055] Figure 2A 2 is a perspective view of the pulse wave measurement device 20. In the first embodiment, a ring-shaped device worn on the user's finger is used as the pulse wave measurement device 20. The photoelectric pulse wave sensor 21 includes two light emitting elements 21A and 21B and one light receiving element 21C. The two light emitting elements 21A and 21B and the one light receiving element 21C are arranged on the inner surface of the ring-shaped wearing member 27. In addition, it is also possible to set a structure including only one of the light emitting elements 21A and 21B.

[0056] When the wearing member 27 is worn on a finger, the light emitting elements 21A and 21B output light toward the finger. The light receiving element 21C is mounted at a position where light reflected by biological tissue inside the finger or light transmitted through the biological tissue enters.

[0057] The light emission control unit 22, the pulse wave measurement unit 23, and the communication unit 24 are also embedded in the wearing member 27. The light emission control unit 22, the pulse wave measurement unit 23, and the communication unit 24 may be formed of a single integrated circuit.

[0058] Figure 2B Schematic diagram of the photoelectric pulse wave sensor 21 and the biological tissue in a state where the pulse wave measurement device 20 is worn on a finger. The light emitting elements 21A, 21B and the light receiving element 21C are in contact with the body surface 70 of the user. The light emitting elements 21A, 21B irradiate the measurement light toward the body surface 70. The irradiated light is absorbed, reflected or scattered (hereinafter sometimes referred to as "reflection") by the epidermal area 71, the arteriole 72 and the capillary 73 in the body surface 70. A part of the light that has passed through the biological tissue such as the epidermal area 71, the arteriole 72 and the capillary 73 is incident on the light receiving element 21C.

[0059] The arteriole 72 is, for example, a thin blood vessel with a diameter of 20 μm or more and 200 μm or less, and exists between the artery and the capillary 73. A plurality of capillaries 73 branch out from the arteriole 72. The capillary 73 is, for example, a thin blood vessel with a diameter of about 10 μm, and connects the artery and the vein. A plurality of capillaries 73 are distributed in an area shallower than the area where the arteriole 72 is distributed. The blood in the artery contains hemoglobin, and hemoglobin has the property of absorbing the light used for measurement. The blood flow changes with the pulsation of the heart, and the amount of light absorbed also changes in accordance with the change in blood flow. Therefore, the intensity of the light received by the light receiving element 21C changes with the pulsation of the heart.

[0060] As the light emitting element 21A, for example, a light emitting element that outputs light in a wavelength range from blue to yellow-green (a wavelength range of 450 nm to 570 nm) is used, and preferably a light emitting element that outputs light in a wavelength range of 500 nm to 550 nm is used. The light emitting element 21B outputs light in a wavelength range from red to near-infrared light, and preferably outputs light in a wavelength range of 750 nm to 950 nm. The light emitting elements 21A and 21B use, for example, light emitting diodes (LEDs), vertical cavity surface emitting lasers (VCSELs), etc. The light receiving element 21C uses, for example, photodiodes (PDs), phototransistors, etc.

[0061] Biological tissue absorbs much light in the wavelength range from blue to yellow-green. Therefore, the pulse wave acquired using light in the wavelength range from blue to yellow-green reflects information about an area shallow from the skin surface, particularly an area shallower than the area where the arterioles 72 are distributed and where the capillaries 73 are mainly distributed. Figure 2B The arrow from the light emitting element 21A toward the light receiving element 21C does not indicate the path of light propagation, but indicates that the light output from the light emitting element 21A passes through the epidermal region 71 and the region where the capillaries 73 are mainly distributed and enters the light receiving element 21C. In order to reflect a large amount of information of the region shallower than the region where the arterioles 72 are distributed and where the capillaries 73 are mainly distributed in the acquired pulse wave, it is preferable to shorten the interval L1 between the light emitting element 21A and the light receiving element 21C. For example, it is preferable to set the interval L1 to be greater than 1 mm and less than 3 mm.

[0062] Light with a wavelength shorter than 450 nm may damage living tissue. In order not to damage living tissue, the wavelength of light used in the measurement of the pulse wave is preferably 450 nm or more.

[0063] The absorption of light in the wavelength range from red to near infrared by biological tissue is less than that in the wavelength range from blue to yellow-green. Therefore, the pulse wave acquired using the light in the wavelength range from red to near infrared reflects information of areas deeper than the skin surface.

[0064] For example, information on the areas where the capillaries 73 and arterioles 72 are distributed is reflected. Figure 2B The arrow from the light emitting element 21B toward the light receiving element 21C does not indicate the path of light propagation, but indicates that the light output from the light emitting element 21B passes through not only the region where the capillaries 73 are distributed but also the region where the arterioles 72 are distributed and enters the light receiving element 21C. In order to reflect a large amount of information on the region where the arterioles 72 and capillaries 73 are distributed in the acquired pulse wave, it is preferable that the interval L2 between the light emitting element 21B and the light receiving element 21C is set to be greater than or equal to 5 mm and less than or equal to 20 mm.

[0065] The absorbance of hemoglobin decreases in a wavelength range longer than 950 nm, so it is preferable to use light in a wavelength range of 950 nm or less to acquire a pulse wave signal.

[0066] exist Figure 2B In the example shown, one light receiving element 21C is arranged for two light emitting elements 21A and 21B, but one light receiving element may be arranged for one light emitting element 21A and another light receiving element may be arranged for the other light emitting element 21B.

[0067] Figure 3 1 is a flowchart showing the process of the vascular endothelial function evaluation method of the first embodiment. Before evaluation, the user wraps the cuff of the cuff-type blood pressure monitor 50 around one upper arm or wrist. Figure 2A ) is worn on the base of the index finger on the same side of the arm around which the cuff is wound. In addition, the finger on which the pulse wave measurement device 20 is worn may also be a finger other than the index finger, or may be worn on a fingertip.

[0068] First, control terminal 30 ( Figure 1 ) controls the pulse wave measuring device 20 ( Figure 1 ), thereby starting the measurement of the pulse wave (step SA1). The measured pulse wave is sent to the server 40 ( Figure 1 ). After that, the control terminal 30 controls the cuff-type blood pressure monitor 50 ( Figure 1 ), thereby starting the blood drive, and releasing the blood drive after a certain period of time (step SA2).

[0069] The pulse wave characteristic quantity calculation unit 41 of the server 40 calculates the pulse wave characteristic quantity of the waveform of the pulse wave from the release time point of the expulsion of blood to the predetermined evaluation time for each beat (step SA3). The length of the evaluation time is preset. Thereafter, the peripheral blood pressure index calculation unit 42 of the server 40 calculates the peripheral blood pressure index for each beat of the pulse wave based on the calculated value of the pulse wave characteristic quantity from the release time point of the expulsion of blood to the evaluation time (step SA4). Thus, the time change of the peripheral blood pressure index within the evaluation time is obtained.

[0070] Next, the endothelial function evaluation unit 43 of the server 40 evaluates the endothelial function based on the plurality of calculated values ​​of the peripheral blood pressure index (step SA5). The endothelial function evaluation unit 43 sends the evaluation result to the control terminal 30. The control unit 31 of the control terminal 30 outputs the evaluation result received from the server 40 to the output unit 32 (step SA6). For example, the endothelial function is evaluated at five levels, namely, level 1 to level 5.

[0071] Next, refer to Figure 4 and Figure 5 Various characteristic quantities of the pulse wave will be described.

[0072] Figure 4 This is a graph showing an example of a pulse wave, a velocity pulse wave, and an acceleration pulse wave.

[0073] The pulse wave feature value calculation unit 41 of the server 40 ( Figure 1 ) The first-order differentiation and the second-order differentiation of the pulse wave are performed. The waveforms obtained by performing the first-order differentiation and the second-order differentiation of the pulse wave are respectively called the velocity pulse wave and the acceleration pulse wave. For example, the intensity of the pulse wave that is discretely distributed at a time interval corresponding to the sampling rate is numerically differentiated at a time interval equivalent to the sampling rate, thereby obtaining the velocity pulse wave. The acceleration pulse wave is also obtained by numerically differentiating the magnitude of the velocity pulse wave.

[0074] Figure 4 The horizontal axis represents time in units of [s], the left vertical axis represents the magnitude of the velocity pulse wave and the acceleration pulse wave normalized with the maximum value being 1, and the right vertical axis represents the magnitude of the pulse wave in arbitrary units. Figure 4 The solid line, long dashed line and short dashed line in the graph shown represent the pulse wave, velocity pulse wave and acceleration pulse wave respectively. Generally speaking, there are five peaks in the acceleration pulse wave in one beat. The first peak, second peak, third peak, fourth peak and fifth peak in one beat are called a wave, b wave, c wave, d wave and e wave respectively.

[0075] The full width at half maximum of the first upward peak of the velocity pulse wave is marked as "VE0.5". The difference between the peak of the a wave and the peak of the b wave is marked as "ab", and the difference between the peak of the a wave and the peak of the d wave is marked as "ad". A concave portion called a notch IC appears slightly behind the maximum peak of the pulse wave.

[0076] Figure 5 : is a graph showing an example of a pulse wave and an accelerated pulse wave. The horizontal axis represents time, the left vertical axis represents the size of the pulse wave in arbitrary units, and the right vertical axis represents the size of the accelerated pulse wave in arbitrary units. The five scales on the horizontal axis are equivalent to 0.2s. The peak value of the a wave of the accelerated pulse wave is marked as "a", and the amplitude of the pulse wave is marked as "S". The amplitude S of the pulse wave is equivalent to the difference between the minimum value and the maximum value after the waveform is corrected in such a way that the minimum values ​​of the pulse waves of two consecutive beats become the same size.

[0077] Next, the peripheral blood pressure index will be described.

[0078] In this specification, "peripheral blood pressure" is defined as the blood pressure in the peripheral arterioles and capillaries. Peripheral blood pressure is sometimes used to mean the blood pressure at the wrist or ankle measured with a cuff-type sphygmomanometer, but the blood pressure at the wrist or ankle is a measurement value at the thick artery (radial artery, etc.), which is different from the peripheral blood pressure defined in this specification. As the blood pressure moves from the thick artery to the arteriole and capillaries, the blood pressure in the blood vessels decreases. The degree of blood pressure reduction varies depending on the measurement site, each person's vascular condition (presence of arteriosclerosis, etc.), mental state (state of the autonomic nervous system, etc.), environment (temperature, presence of noise, etc.), clothing worn, etc.

[0079] Among the characteristic quantities of the pulse wave, an effective index for obtaining the peripheral blood pressure is adopted as the peripheral blood pressure index. The peripheral blood pressure index is considered to have the following characteristics.

[0080] First, when blood vessels are healthy and vascular resistance does not change, the peripheral blood pressure index is positively correlated with the blood pressure at the upper arm and wrist. Second, if the vicinity of the measurement site is cooled to constrict blood vessels, the peripheral blood pressure index decreases. If blood vessels constrict, peripheral vascular resistance increases, so blood pressure at the upper arm and wrist may rise.

[0081] As pulse wave feature quantities reflecting the above-mentioned two features of the peripheral blood pressure index, the following three feature quantities can be cited.

[0082] The reciprocal of the full width at half maximum "VE0.5" (hereinafter, referred to as "1 / (VE0.5)").

[0083] The ratio of the peak value a of the a wave of the acceleration pulse wave to the amplitude S of the pulse wave (hereinafter referred to as "a / S").

[0084] The ratio of the difference "ab" between the peak value of the a wave and the peak value of the b wave of the acceleration pulse wave to the difference "ad" between the peak value of the a wave and the peak value of the d wave (hereinafter, indicated as "(ab) / (ad)").

[0085] In this specification, these characteristic quantities of the waveform of the pulse wave are referred to as “peripheral blood pressure indices.” These peripheral blood pressure indices are related to the steepness of the rise of the pulse wave.

[0086] Fig. 6A and Figure 6B This is a graph showing the relationship between the value of the peripheral blood pressure index "1 / VE0.5" obtained from the pulse wave measured when the height from the heart to the measured part (finger) is changed, and when the height of the measured part is made consistent with the chest and the vicinity of the elbow on the side where the finger, which is the measured part, is located is cooled, and the systolic blood pressure measured at the wrist. Fig. 6A and Figure 6B The light emitting element 21A ( Figure 2A ) outputs green light and in the measurement of the pulse wave, the light from the light emitting element 21B ( Figure 2A ) output near-infrared light. The pulse wave measured using green light mainly reflects the capillary 73 ( Figure 2B ) is reflected in the pulse wave measured using near-infrared light, which is caused by changes in blood flow in the capillaries 73 and arterioles 72 ( Figure 2B ) changes in blood flow.

[0087] Fig. 6A and Figure 6B The horizontal axis of the graph represents the systolic blood pressure at the wrist in units of [mmHg], and the vertical axis represents the systolic blood pressure in units of [s -1 ] is used to represent the peripheral blood pressure index "1 / (VE0.5)". In each graph, the results obtained by measuring three subjects A, B, and C are shown by triangular symbols, square symbols, and circular symbols, respectively. The three hollow symbols shown for each subject respectively show the values ​​of the peripheral blood pressure index "1 / VE0.5" obtained by setting the height of the measured part (finger) to the height of the navel, chest, and forehead. The value of the peripheral blood pressure index "1 / VE0.5" decreases in the order of the height of the measured part to the navel, chest, and forehead. The black-filled symbols shown for each subject show the values ​​of the peripheral blood pressure index "1 / VE0.5" obtained by setting the height of the measured part to the height of the chest and cooling the vicinity of the elbow.

[0088] Although there are differences in degree depending on the subject, it is known that when the height of the measured part is changed, the peripheral blood pressure index "1 / VE0.5" has a roughly positive correlation with the systolic blood pressure at the wrist. And, although there are some exceptions, it is known that the peripheral blood pressure index "1 / VE0.5" decreases when the blood vessels are contracted by cooling the vicinity of the measured part. The appearance of this change is consistent with the characteristics of the assumed peripheral blood pressure index. Therefore, the peripheral blood pressure index "1 / VE0.5" is considered to be an effective index for estimating peripheral blood pressure.

[0089] In addition, according to Fig. 6A and Figure 6B The results shown show that, in the measurement of the peripheral blood pressure index "1 / VE0.5", it is more preferable to use green light than to use near-infrared light. In addition, as an index replacing the peripheral blood pressure index "1 / VE0.5", the reciprocal of the parameter representing the width of the maximum peak of the velocity pulse wave may be used. In addition, the exponent of the parameter representing the width of the maximum peak of the velocity pulse wave may be used with a negative exponent. More generally, the following function may be used as a peripheral blood pressure index, the function using the parameter representing the width of the maximum peak of the velocity pulse wave as a variable, and the value of the function becomes smaller as the width of the peak increases.

[0090] Fig. 7A and Figure 7B This is a graph showing the relationship between the value of the peripheral blood pressure index "a / S" obtained from the pulse wave measured when the height from the heart to the measured part (finger) is changed, and when the height of the measured part is made consistent with the chest and the vicinity of the elbow on the side where the finger, which is the measured part, is located is cooled, and the systolic blood pressure measured at the wrist. Fig. 7A and Figure 7B The measurement results are shown respectively when green light is used for the measurement of the pulse wave and when near-infrared light is used for the measurement of the pulse wave.

[0091] Fig. 7A and Figure 7B The horizontal axis of the graph represents the systolic blood pressure at the wrist in units of [mmHg], and the vertical axis represents the peripheral blood pressure index "a / S" in arbitrary units. Fig. 7A and Figure 7B The meaning of each symbol is Fig. 6A and Figure 6B The symbols in the diagrams shown have the same meaning.

[0092] Fig. 7A and Figure 7B The results of the assays shown are consistent with Fig. 6A and Figure 6BThe measurement results shown in the figure have roughly the same trend. Therefore, the peripheral blood pressure index "a / S" is considered to be an effective index for estimating peripheral blood pressure. Fig. 7A and Figure 7B The results shown show that, in the measurement of the peripheral blood pressure index "a / S", it is more preferable to use green light than to use near-infrared light.

[0093] Instead of the peripheral blood pressure index "a / S", the product of the positive power of the peak value a of the a wave of the acceleration pulse wave and the negative power of the amplitude S of the pulse wave may be used as the peripheral blood pressure index. Alternatively, the peripheral blood pressure index may be calculated based on information related to the peak value of the a wave of the acceleration pulse wave and the amplitude of the pulse wave signal. For example, the following function may be used as the peripheral blood pressure index, which has the peak value a and the amplitude S as variables, and the value of the function increases if the peak value a increases, and the value of the function decreases if the amplitude S increases.

[0094] Fig. 8A and Figure 8B This is a graph showing the relationship between the value of the peripheral blood pressure indicator "(ab) / (ad)" obtained from the pulse wave measured when the height from the heart to the measured part (finger) is changed, and when the height of the measured part is made consistent with the chest and the vicinity of the elbow on the side where the finger, which is the measured part, is located is cooled, and the systolic blood pressure measured at the wrist. Fig. 8A and Figure 8B The measurement results are shown respectively when green light is used for the measurement of the pulse wave and when near-infrared light is used for the measurement of the pulse wave.

[0095] Fig. 8A and Figure 8B The horizontal axis of the graph represents the systolic blood pressure at the wrist in units of [mmHg], and the vertical axis represents the peripheral blood pressure index "(ab) / (ad)". Fig. 8A and Figure 8B The meaning of each symbol is Fig. 6A and Figure 6B The symbols in the diagrams shown have the same meaning.

[0096] Fig. 8A and Figure 8B The results of the assays shown are consistent with Fig. 6A and Figure 6B The measurement results shown have substantially the same tendency. Therefore, the peripheral blood pressure index "(ab) / (ad)" is considered to be an effective index for estimating peripheral blood pressure.

[0097] Instead of the peripheral blood pressure index "(ab) / (ad)", the peripheral blood pressure index may be calculated based on information about the difference between the peak of the a wave and the peak of the b wave of the acceleration pulse wave, and the difference between the peak of the a wave and the peak of the d wave. For example, a function may be used as a peripheral blood pressure index, which uses the difference (ab) between the peak of the a wave and the peak of the b wave, and the difference (ad) between the peak of the a wave and the peak of the d wave as variables, and increases the value of the function when the value of the difference (ab) increases, and decreases the value of the function when the value of the difference (ad) increases.

[0098] Next, refer to Figures 9 to 14C The accompanying drawings illustrate a method for evaluating vascular endothelial function using a peripheral blood pressure index.

[0099] Fig. 9 2 is a graph showing the pulse wave obtained from the subject A whose blood pressure is within the normal range. The horizontal axis represents the time elapsed from the start of pulse wave measurement in units of [s], and the vertical axis represents the photoelectric pulse wave (the pulse wave from the photoelectric pulse wave sensor 21 ( Figure 1 )'s output is inverted). Fig. 9 The solid lines Gr and Ir in the graph of respectively represent the measurement results when green light is used and when near-infrared light is used. The systolic blood pressure of the subject A is 115 mmHg, the diastolic blood pressure is 76 mmHg, and the pulse rate is 65 bpm.

[0100] About 30 seconds after the start of pulse wave measurement, the cuff-type blood pressure monitor 50 starts to pressurize. It takes about ten seconds from the start of pressurization to the start of blood expulsion. When blood expulsion starts, the pulse wave cannot be obtained. About 60 seconds after the start of pulse wave measurement, the pressure in the cuff decreases and the pulse wave can be detected. The period of blood expulsion is marked as Pa. Fig. 9 The blood removal period is indicated in light grey in the middle. The measurement was terminated at a time point when about 120 seconds had passed from the start of the measurement.

[0101] FIG. 10A to FIG. 10F The graphs show temporal changes in peripheral blood pressure indices, and the horizontal axes of these graphs represent the elapsed time in units of [s]. Fig. 10A and Fig. 10D The vertical axis of the graph is in units [s -1 ] to represent the peripheral blood pressure index "1 / VE0.5", Fig. 10B and Fig.10E The vertical axis of the graph represents the peripheral blood pressure index "a / S" in arbitrary units. Fig. 10C and Fig.10F The vertical axis of the graph represents the peripheral blood pressure index "(ab) / (ad)". FIG. 10A to FIG. 10CThe graph shows the peripheral blood pressure index obtained from the pulse wave measured using green light. FIG. 10D to FIG. 10F The graph of shows the peripheral blood pressure index obtained from the pulse wave measured using near-infrared light.

[0102] Fig.11 2 is a graph showing the pulse wave obtained from another subject B whose blood pressure is within the normal range. The horizontal axis represents the time elapsed from the start of pulse wave measurement in units of [s], and the vertical axis represents the photoelectric pulse wave (the pulse wave from the photoelectric pulse wave sensor 21 ( Figure 1 )'s output is inverted). Fig.11 The solid lines Gr and Ir in the graph of respectively represent the measurement results when green light is used and when near-infrared light is used. The systolic blood pressure of the subject B is 104 mmHg, the diastolic blood pressure is 76 mmHg, and the pulse rate is 66 bpm.

[0103] The period of time from the start of pulse wave measurement to the end of pulse wave measurement by the cuff type blood pressure monitor 50 is the same as Fig. 9 The same situation is shown. The period of blood expulsion is marked as Pa. Fig.11 The blood expulsion period is marked in light grey.

[0104] FIG. 12A to FIG. 12F The graphs show temporal changes in peripheral blood pressure indices, and the horizontal axes of these graphs represent the elapsed time in units of [s]. Fig. 12A and Fig.12D The vertical axis of the graph is in units [s -1 ] to represent the peripheral blood pressure index "1 / VE0.5", Fig. 12B and Fig.12E The vertical axis of the graph represents the peripheral blood pressure index "a / S" in arbitrary units. Fig. 12C and Fig.12F The vertical axis of the graph represents the peripheral blood pressure index "(ab) / (ad)". FIG. 12A to FIG. 12C The graph shows the peripheral blood pressure index obtained from the pulse wave measured using green light. FIG. 12D to FIG. 12F The graph of shows the peripheral blood pressure index obtained from the pulse wave measured using near-infrared light.

[0105] Whether it is the peripheral blood pressure index ( FIG. 10A to FIG. 10F ), the peripheral blood pressure index obtained from the pulse wave measured by subject B using green light ( Fig. 12A , Fig. 12B , Fig. 12CWhich of the peripheral blood pressure indicators in the graph of ( ) is lower immediately after the release of blood expulsion than before the start of blood expulsion. When about 10 seconds have passed since the release of blood expulsion, the peripheral blood pressure indicator returns to the value before the start of blood expulsion. In addition, compared with the decrease in the peripheral blood pressure indicator of subject B, the decrease in the peripheral blood pressure indicator of subject A is more significant. The peripheral blood pressure indicator ( Fig.12D , Fig.12E , Fig.12F No significant decrease was observed just after release of the blood drive.

[0106] The mechanism of the decrease in peripheral blood pressure index just after the release of blood expulsion can be considered as follows. When the endothelial function is normal, if blood expulsion is released, the blood vessels will expand due to the endothelial function. The blood flowing into the large blood vessels is consumed to expand the large blood vessels, so the rapid inflow of blood into the downstream capillaries can be suppressed. As a result, the increase in peripheral blood pressure index is suppressed during the period of about 10 seconds from the time of blood expulsion release.

[0107] Fig.13 : is a graph showing a pulse wave acquired from a subject C whose blood pressure is out of the normal range. For this subject, it is believed that the vascular endothelial function is decreased. Fig.13 The horizontal axis of the graph shown in the figure represents the time elapsed from the start of pulse wave measurement in units of [s], and the vertical axis represents the photoelectric pulse wave (the pulse wave from the photoelectric pulse wave sensor 21 ( Figure 1 )'s output is inverted). Fig.13 The solid lines Gr and Ir in the graph of respectively represent the measurement results when green light is used and when near-infrared light is used. The systolic blood pressure of the subject C is 164 mmHg, the diastolic blood pressure is 104 mmHg, and the pulse rate is 59 bpm.

[0108] The period of time from the start of pulse wave measurement to the end of pulse wave measurement by the cuff type blood pressure monitor 50 is the same as Fig. 9 The same situation is shown. The period of blood expulsion is marked as Pa. Fig.13 The blood expulsion period is marked in light grey.

[0109] Fig.14A , Fig. 14B as well as Fig. 14C The graphs of show temporal changes in peripheral blood pressure indices. The horizontal axes of these graphs represent elapsed time in units of [s]. Fig.14A The vertical axis of the graph is in units [s -1 ] to represent the peripheral blood pressure index "1 / VE0.5", Fig. 14B The vertical axis of the graph represents the peripheral blood pressure index "a / S" in arbitrary units. Fig. 14CThe vertical axis of the graph represents the peripheral blood pressure index "(ab) / (ad)". FIG. 14A to FIG. 14C The graph of shows the peripheral blood pressure index obtained from the pulse wave measured using green light. It is not possible to calculate a clear pulse wave feature value from the pulse wave acquired using near-infrared light.

[0110] In either case, the peripheral blood pressure index increases immediately after the exsanguination is released compared to before the exsanguination is started. When about 10 seconds have passed since the exsanguination is released, the peripheral blood pressure index returns to the value before the exsanguination is started. The mechanism of the increase in the peripheral blood pressure index immediately after the exsanguination is released can be considered as follows.

[0111] When endothelial function is reduced, blood vessels do not dilate sufficiently even if blood is released. Blood that has flowed into large blood vessels flows directly into arterioles and capillaries downstream, so peripheral blood pressure indexes are thought to rise.

[0112] like Figures 9 to 14C As shown in the graph of the attached figure, it can be seen that the time change of the peripheral blood pressure index from the time point of blood expulsion release to a certain time is different for people with normal endothelial function and people with decreased endothelial function. In the first embodiment, the difference in the behavior of the peripheral blood pressure index after blood expulsion release is used to evaluate the endothelial function.

[0113] Next, the evaluation method of vascular endothelial function is described. Based on the pulse wave from the time point of blood drainage release to the time point when a certain period of time (hereinafter referred to as evaluation time ET) has passed, the peripheral blood pressure index is calculated. Fig. 10A An example of the evaluation time ET is shown in FIG. The evaluation time is divided into the front period ET 1 and the period ET of the rear side 2 , and calculate the period ET of the front side 1 The mean value of peripheral blood pressure index M 1 The mean value M of the peripheral blood pressure index during the period of the back 2 .

[0114] ET based on the front side 1 The mean value of peripheral blood pressure index M 1 and the period ET of the rear side 2 The mean value of peripheral blood pressure index M 2 To evaluate endothelial function. 1 The mean value of peripheral blood pressure index M 1 Except for the period ET on the back side 2 The mean value of peripheral blood pressure index M 2 The obtained value (in this specification, M 1 / M 2The larger the value of the vascular endothelial function evaluation index (called the vascular endothelial function evaluation index), the more the vascular endothelial function is considered to be reduced. 1 / M 2 The endothelial function can be evaluated in five levels based on the size of 1 With M 2 The difference was used to evaluate endothelial function.

[0115] When the peripheral blood pressure indexes of subjects A, B, and C before blood removal were compared, the peripheral blood pressure index of subject A was the highest, and the peripheral blood pressure index of subject C was the lowest. 1 / M 2 When comparing the size of the vascular endothelial function evaluation index M of subject A 1 / M 2 Minimum, endothelial function evaluation index M of subject C 1 / M 2 It is considered that the peripheral blood pressure index before blood removal tends to be lower in subjects with lower endothelial function.

[0116] As an example, it is preferable to set the evaluation time ET to 40 seconds, and divide the time point at which 10 seconds have passed from the blood release time point into the front period ET 1 and the period ET of the rear side 2 It is preferred to refer to data obtained from many subjects to determine the evaluation time ET and to set the front period ET 1 ET during the period with the back 2 The point in time at which the distinction is made.

[0117] For people whose blood pressure is above the normal range, sometimes Fig.13 As described above, the pulse wave feature cannot be calculated from the pulse wave acquired using near-infrared light. In order to stably calculate the pulse wave feature even for people whose blood pressure is higher than the normal range, it is preferable to acquire the pulse wave using light in the wavelength range from blue to yellow-green.

[0118] Next, the excellent effects of the first embodiment will be described.

[0119] In the first embodiment, the blood flow site of the upstream artery is pressurized to flow blood, and the peripheral blood pressure of the arterioles and capillaries on the downstream side is measured to evaluate the vascular endothelial function. Therefore, the vascular endothelial function from the blood flow site to the arterioles and capillaries can be evaluated.

[0120] Next, a modification of the first embodiment will be described.

[0121] In the first embodiment, as the pulse wave for calculating the peripheral blood pressure index, a photoelectric pulse wave sensor 21 ( Figure 1 ) measured by a photoelectric pulse wave, but a pulse wave measured by another sensor may also be used. For example, a pressure pulse wave may also be used.

[0122] In the first embodiment, the evaluation time ET ( Fig. 10A ) is divided into the front period ET 1 and the period ET of the rear side 2 , and the vascular endothelial function is evaluated based on the ratio of the average values ​​of the peripheral blood pressure indexes in the two periods, but other methods may be used to evaluate the vascular endothelial function. For example, the vascular endothelial function may be evaluated based on a plurality of calculated values ​​of the peripheral blood pressure indexes in the evaluation time ET. For example, the vascular endothelial function may be evaluated based on the trend of the time change of a plurality of calculated values ​​of the peripheral blood pressure indexes in the evaluation time ET.

[0123] In the first embodiment, as the pulse wave measurement device 20 ( Figure 2A ), a ring-shaped device worn on a finger is used, but devices of other shapes may also be used. For example, a clip-shaped device worn on a fingertip may also be used. In addition, as the pulse wave measurement device 20, in addition to using a device worn on a finger, a watch-shaped or bracelet-shaped device worn on a wrist may also be used.

[0124] In the first embodiment, the upper arm is pressurized to drive blood and the pulse wave is measured at the finger, but the blood drive site and the pulse wave measurement site are not limited to this. It is preferred to pressurize a part of the body to drive blood and measure the pulse wave at a site farther from the heart than the pressurized site.

[0125] In the first embodiment, the control terminal 30 ( Figure 1 ) controls the blood flow and release of the cuff-type blood pressure monitor 50, but as a device for blood flow and release, an independent device that does not communicate with the control terminal 30 may be used. For example, a cuff-type blood pressure monitor that does not communicate with the control terminal 30 may be used, or a liquid-free blood pressure monitor may be used. In this case, it is preferred that the user or a person nearby performs the operation of pressurizing and releasing the cuff. The pulse wave feature quantity calculation unit 41 ( Figure 1 ) can detect the start and release time of blood expulsion based on the acquired pulse wave.

[0126] In the first embodiment, if Figure 1As shown, the pulse wave measurement device 20, the control terminal 30 and the server 40 share various functions, but other functions can also be shared. For example, the control terminal 30 can also be used to realize the function of the pulse wave feature amount calculation unit 41. In addition, the control terminal 30 can also be used to realize all the functions of the server 40. Conversely, the server 40 can also be used to realize all the functions of the control terminal 30.

[0127] In the first embodiment, the peripheral blood pressure index calculated from the pulse wave after the exsanguination is used to evaluate the endothelial function. However, the peripheral blood pressure index calculated from the pulse wave for a certain period of time before the exsanguination may be used instead of the peripheral blood pressure index calculated from the pulse wave for a certain period of time before the exsanguination. 2 For example, the average value of the peripheral blood pressure index for a certain period of time before blood removal can be used instead of Fig. 10A The period ET after the evaluation time ET shown 2 That is, the average value of the peripheral blood pressure index during the period ET can also be 1 The average value of the peripheral blood pressure index is compared with the average value of the peripheral blood pressure index for a certain period of time before blood removal.

[0128] In addition, you can also use ET according to the period after blood expulsion release 1 and during ET 2 The endothelial function can be evaluated based on the peripheral blood pressure index calculated from the pulse wave of the blood flow and the peripheral blood pressure index calculated from the pulse wave for a certain period of time before the blood flow. 2 The average value of peripheral blood pressure index and the period ET 1 The peripheral blood pressure index of a certain period of time before blood removal and the average value of ET during the period were used to evaluate endothelial function. 2 The average value of the peripheral blood pressure index can be either a simple average or a value based on the relative period ET. 1 The value obtained by taking the weighted average of the time deviations.

[0129] It can also replace the peripheral blood pressure index and ET during a certain period of time before blood removal. 2 The average value of peripheral blood pressure index is calculated, and the waveform and period ET of peripheral blood pressure index for a certain period of time before blood removal are calculated. 2 The waveform of the peripheral blood pressure index is approximated by a straight line or a curve, and the peripheral blood pressure index and the period ET for a certain period of time before the blood removal are obtained based on the approximate straight line or the approximate curve. 2 The representative value of the peripheral blood pressure index is preferably based on the representative value and the period ET after the exsanguination release. 1The endothelial function is evaluated by taking the average value of the peripheral blood pressure index. As a representative value, for example, the value at the midpoint of the approximate straight line or the approximate curve is preferably used.

[0130] Peripheral blood pressure indexes fluctuate due to exercise, rapid temperature changes, stress, tension, etc. By evaluating endothelial function with reference to the peripheral blood pressure index before blood removal, the influence of fluctuations in peripheral blood pressure indexes caused by various factors can be reduced, thereby improving the evaluation accuracy. Fig. 10A ET during the period shown 2 When the average value of the peripheral blood pressure index in the blood flow meter is greatly different from the average value of the peripheral blood pressure index before blood flow metering, it is preferable to notify the user to measure the pulse wave again.

[0131] In the first embodiment, the control terminal 30 ( Figure 1 ) controls the pulse wave measuring device 20 ( Figure 1 ) and cuff-type blood pressure monitor 50( Figure 1 ), but it is also possible that the pulse wave measurement device 20 communicates directly with the cuff-type blood pressure monitor 50, and the pulse wave measurement device 20 controls the timing of pressurization and release of the cuff-type blood pressure monitor 50.

[0132] Preferably, the pulse wave measuring device 20 measures the pulse wave in synchronization with the timing of pressurization and release of the cuff-type blood pressure monitor 50. Thus, the blood pressure can be measured in parallel with the pulse wave measurement. Since blood expulsion starts after a certain time has passed since the start of pressurization, the control terminal 30 obtains the timing information of pressurization and release from the pulse wave measuring device 20, thereby easily determining the timing of blood expulsion and release.

[0133] [Second embodiment]

[0134] Next, refer to Figures 15 to 17 The vascular endothelial function evaluation system and vascular endothelial function evaluation method of the second embodiment are described with reference to FIG. Figures 1 to 14C The vascular endothelial function evaluation system and vascular endothelial function evaluation method of the first embodiment described in the accompanying drawings are the same as the structure. In the first embodiment, the blood-driving period Pa ( Fig. 9 , Fig.11 , Fig.13 ) is set to about 30 seconds. In the second embodiment, the blood-driving time is further extended.

[0135] Fig.15 It shows that the Fig. 9The pulse wave of the subject A shown in FIG. 1 is measured by extending the blood expulsion time. The horizontal axis represents the time elapsed from the start of the pulse wave measurement in units of [s], and the vertical axis represents the photoelectric pulse wave (the pulse wave from the photoelectric pulse wave sensor 21 ( Figure 1 )). To adjust the blood expulsion time, the pressure site was pressurized using a cuff of an aneroid sphygmomanometer. Fig.15 The solid lines Gr and Ir in the graph of respectively represent the measurement results when green light is used and when near-infrared light is used.

[0136] About 30 seconds after the start of pulse wave measurement, the aneroid sphygmomanometer starts to pressurize. It takes about 10 seconds from the start of pressurization to the start of blood expulsion. When blood expulsion starts, the pulse wave cannot be obtained. About 150 seconds after the start of pulse wave measurement, the air in the cuff is evacuated. The period of blood expulsion is marked as Pa. Fig.15 The blood removal period is indicated in light grey in the figure. The measurement was terminated at a time point when about 300 seconds had passed from the start of the measurement.

[0137] FIG. 16A to FIG. 16F The graphs show temporal changes in peripheral blood pressure indices, and the horizontal axes of these graphs represent the elapsed time in units of [s]. Fig.16A and Fig.16D The vertical axis of the graph is in units [s -1 ] to represent the peripheral blood pressure index "1 / VE0.5", Fig. 16B and Fig.16E The vertical axis of the graph represents the peripheral blood pressure index "a / S" in arbitrary units. Fig. 16C and Fig.16F The vertical axis of the graph represents the peripheral blood pressure index "(ab) / (ad)". FIG. 16A to FIG. 16C The graph shows the peripheral blood pressure index obtained from the pulse wave measured using green light. FIG. 16D to FIG. 16F The graph of shows the peripheral blood pressure index obtained from the pulse wave measured using near-infrared light.

[0138] When the blood-driving time is relatively short, FIG. 10A to FIG. 10F The graph is similar to the one measured under the condition of relatively long blood removal time. FIG. 16A to FIG. 16F When comparing the charts of

[0139] The phenomenon that the peripheral blood pressure index decreases when the exsanguination is released compared to before the exsanguination occurs regardless of the exsanguination time. When the exsanguination time is relatively short, the peripheral blood pressure index returns to its original value in about 10 seconds. In contrast, when the exsanguination time is relatively long, it takes longer for the peripheral blood pressure index to return to its original value. For example, when the green light is used for measurement, it takes about 30 seconds for the peripheral blood pressure index to return to its original value, and when the near-infrared light is used for measurement, it takes about 120 seconds for the peripheral blood pressure index to return to its original value. In addition, if the exsanguination time is extended, the peripheral blood pressure index measured using near-infrared light is significantly reduced compared to the case where the exsanguination time is short.

[0140] The mechanism of the phenomenon that it takes time for the peripheral blood pressure index to return to the original value when near-infrared light is used can be considered as follows. If the large blood vessels dilate during the blood expulsion, the inflow of blood into the capillaries is suppressed, so the peripheral blood pressure index decreases. If the blood expulsion time is long, the blood flow in the capillaries and arterioles decreases, and it takes time until the capillaries are filled with blood. It also takes time for the blood to fill the arterioles.

[0141] In the measurement of pulse waves using green light, the information of blood flow in capillaries is mainly reflected in the pulse wave, while in the measurement of pulse waves using near-infrared light, the information of blood flow in arterioles is easily reflected in the pulse wave in addition to the information of blood flow in capillaries. Therefore, the peripheral blood pressure index measured using near-infrared light returns to its original value at the time when blood fills not only capillaries but also arterioles. Therefore, the time for the peripheral blood pressure index measured using near-infrared light to return to its original value is longer than the time for the peripheral blood pressure index measured using green light to return to its original value.

[0142] Fig.17 1 is a flowchart showing the process of the vascular endothelial function evaluation method of the second embodiment. First, the user determines the blood drainage time (step SB1). The determined blood drainage time is input by the user into the control terminal 30 ( Figure 1 ). The control unit 31 of the control terminal 30 sets the evaluation time according to the input blood removal time (step SB2). Then, the control unit 31 and the first embodiment ( Figure 3 ) Similarly, pulse wave measurement begins (step SA1).

[0143] In the first embodiment ( Figure 3 ), blood expulsion and release are performed based on a fixed blood expulsion time (step SA2). In the second embodiment, blood expulsion and release are performed based on the blood expulsion time set in step SB2 (step SB3). The subsequent steps SA3 to SA5 are the same as those in the first embodiment ( Figure 3 )'s process from step SA3 to step SA5 is the same.

[0144] Next, the excellent effects of the second embodiment will be described.

[0145] In the second embodiment, by extending the exsanguination time compared to the first embodiment, the peripheral blood pressure index after the exsanguination release clearly shows a decrease, so the evaluation accuracy of the vascular endothelial function can be improved. In addition, by extending the evaluation time in accordance with the increase in the exsanguination time, the decrease and recovery changes of the peripheral blood pressure index after the exsanguination release can be stably detected.

[0146] Next, refer to Fig.18 A vascular endothelial function evaluation method according to a modified example of the second embodiment will be described. Fig.18 : is a flowchart showing the procedure of the vascular endothelial function evaluation method according to the modification of the second embodiment.

[0147] In the second embodiment, the user determines the blood drainage time (step SB1), but in this variant, the wavelength of light used in the measurement of the pulse wave is determined (step SC1). Then, the evaluation time is set according to the wavelength (step SC2). The subsequent process is the same as that of the second embodiment.

[0148] like FIG. 16A to FIG. 16F As shown in the graph of , when near-infrared light is used in the measurement of the pulse wave, the time until the peripheral blood pressure index returns to the original value is longer than when green light is used. Therefore, when near-infrared light is used, it is preferable to extend the evaluation time compared to when green light is used. In this modified example, the evaluation time is determined according to the wavelength of light used in the measurement of the pulse wave, so that the decrease and recovery changes of the peripheral blood pressure index after the release of blood expulsion can be stably detected.

[0149] [Third embodiment]

[0150] Next, refer to Fig.19A and Fig.19B A vascular endothelial function evaluation system and a vascular endothelial function evaluation method according to a third embodiment will be described. Hereinafter, descriptions of the same structures as those of the vascular endothelial function evaluation system and the vascular endothelial function evaluation method according to the first embodiment and the second embodiment will be omitted.

[0151] Fig.19A and Fig.19B It shows that according to Fig.15 The amplitude S( Figure 5 ) and a graph of the time changes of the peripheral blood pressure index "a / S". Fig.19A The graph is based on the pulse wave measured using green light. Fig.19B The graph is obtained based on the pulse wave measured using near-infrared light.

[0152] It can be seen that the amplitude S of the pulse wave from the time of blood expulsion release to 60 seconds is significantly greater than the amplitude S of the pulse wave before blood expulsion. In both the case where the measuring light is green light and the case where the measuring light is near-infrared light, there is a significant trend that the amplitude S of the pulse wave increases. The increase in the amplitude S of the pulse wave is presumably due to the increase in blood flow caused by vasodilation.

[0153] When the endothelial function is good, the blood vessels are fully dilated after the exsanguination is released, and the increase in the amplitude S of the pulse wave becomes larger. When the endothelial function is reduced, the dilation of the blood vessels becomes insufficient, and as a result, the increase in the amplitude S of the pulse wave becomes smaller. In this way, the endothelial function can be evaluated based on the increase in the amplitude S of the pulse wave after the exsanguination is released. In the third embodiment, in addition to the calculated value of the peripheral blood pressure index from the time point of the exsanguination release, the endothelial function is evaluated based on the increase in the amplitude S of the pulse wave.

[0154] Next, the excellent effects of the third embodiment will be described.

[0155] In the third embodiment, the vascular endothelial function is evaluated based on the increase in the amplitude S of the pulse wave in addition to the calculated value of the peripheral blood pressure index from the time point of blood drainage release, thereby improving the evaluation accuracy.

[0156] [Fourth embodiment]

[0157] Next, refer to Fig. 20 and Fig.21 A vascular endothelial function evaluation system and a vascular endothelial function evaluation method according to a fourth embodiment will be described. Hereinafter, descriptions of the same structures as those of the vascular endothelial function evaluation system and a vascular endothelial function evaluation method according to the first embodiment will be omitted.

[0158] Fig. 20 1 is a block diagram of a vascular endothelial function evaluation system according to a fourth embodiment. The vascular endothelial function evaluation system according to the first embodiment includes a pulse wave measurement device 20, a control terminal 30, a server 40, and a cuff-type blood pressure monitor 50. In contrast, the vascular endothelial function evaluation system according to the fourth embodiment further includes a reference pulse wave measurement device 60.

[0159] The reference pulse wave measurement device 60 includes a reference photoelectric pulse wave sensor 61, a light emission control unit 62, a reference pulse wave measurement unit 63, and a communication unit 64. The structures and functions of the reference photoelectric pulse wave sensor 61, the light emission control unit 62, the reference pulse wave measurement unit 63, and the communication unit 64 are the same as those of the photoelectric pulse wave sensor 21, the light emission control unit 22, the pulse wave measurement unit 23, and the communication unit 24 of the pulse wave measurement device 20 of the first embodiment. The reference pulse wave measurement unit 63 generates a reference pulse wave signal based on the output from the reference photoelectric pulse wave sensor 61. When a pulse wave sensor of another type is used instead of the photoelectric pulse wave sensor 21 of the pulse wave measurement device 20, a reference pulse wave sensor that measures the pulse wave in the same manner as the photoelectric pulse wave sensor 21 is used instead of the reference photoelectric pulse wave sensor 61.

[0160] Fig.21 This is a schematic diagram of a user wearing a measuring device when evaluating vascular endothelial function using the vascular endothelial function evaluation system of the fourth embodiment. The user wraps the pressurizing portion 51 of the cuff-type blood pressure monitor 50, such as a cuff, around one upper arm. The pulse wave measurement device 20 is worn on the finger of the arm wearing the pressurizing portion 51. The reference pulse wave measurement device 60 is worn on the finger of the opposite arm. In this way, the reference pulse wave measurement device 60 is mounted on a portion of the human body that is symmetrical to the portion where the pulse wave measurement device 20 is mounted.

[0161] When the pulse wave measurement starts, the pulse wave is acquired by the pulse wave measurement device 20, and the reference pulse wave is acquired by the reference pulse wave measurement device 60. The peripheral blood pressure index obtained from the pulse wave acquired by the pulse wave measurement device 20 is compared with the peripheral blood pressure index obtained from the reference pulse wave to evaluate the vascular endothelial function.

[0162] The period ET of the peripheral blood pressure index obtained from the pulse wave acquired by the pulse wave measurement device 20 is 1 ( Fig. 10A ) is marked as M 1 ET, the period of the peripheral blood pressure index 2 The mean value is marked as M 2 The period ET of the peripheral blood pressure index obtained by referring to the pulse wave 1 ( Fig. 10A ) is marked as MR 1 ET, the period of the peripheral blood pressure index 2 The mean value is marked as MR 2 In the first embodiment, based on M 1 / M 2 To evaluate vascular endothelial function, but in the fourth embodiment, based on (M 1 / M 2 ) / (MR 1 / MR 2 ) to evaluate endothelial function.

[0163] Next, the excellent effects of the fourth embodiment will be described.

[0164] Regarding the finger from which the reference pulse wave was obtained, since no blood was drawn, the average value MR 1 With MR 2 However, due to some external factors, sometimes the average MR 2 Relative to the mean MR 1 That is, there is MR 1 / MR 2 The influence of this external factor on M 1 / M 2 In the fourth embodiment, based on (M 1 / M 2 ) / (MR 1 / MR 2 ) is used to evaluate vascular endothelial function, thus almost eliminating the influence of external factors, thereby improving the evaluation accuracy of vascular endothelial function.

[0165] The above-mentioned embodiments are illustrative, and it is self-evident that the structures shown in different embodiments can be partially replaced or combined. The same effects obtained by the same structure of multiple embodiments are not mentioned one by one in each embodiment. In addition, the present invention is not limited to the above-mentioned embodiments. For example, it is obvious to those skilled in the art that various changes, improvements, combinations, etc. can be made.

[0166] Description of Reference Numerals

[0167] 20: Pulse wave measuring device; 21: Photoelectric pulse wave sensor; 21A, 21B: Light emitting element; 21C: Light receiving element; 22: Light emitting control unit; 23: Pulse wave measuring unit; 24: Communication unit; 27: Wearing component; 30: Control terminal; 31: Control unit; 32: Output unit; 33: Communication unit; 40: Server; 41: Pulse wave feature quantity calculation unit; 42: Peripheral blood pressure index calculation unit; 43: Vascular endothelial function evaluation unit; 44: Communication unit; 50: Cuff-type sphygmomanometer; 51: Pressurization unit; 52: Pulse detection unit; 53: Control unit; 54: Blood pressure calculation unit; 55: Communication unit; 60: Reference pulse wave measuring device; 61: Reference photoelectric pulse wave sensor; 62: Light emitting control unit; 63: Reference pulse wave measuring unit; 64: Communication unit; 70: User's body surface; 71: Epidermal area; 72: Arteriole; 73: Capillary.

Claims

1. A vascular endothelial function evaluation system comprising: a pulse wave measuring unit that generates a pulse wave signal based on a measurement result of a pulse wave sensor installed at a site farther from the heart than a pressurized site to be pressurized for blood removal; Output section; a peripheral blood pressure index calculation unit that calculates a peripheral blood pressure index related to the steepness of the rise per beat of the pulse wave signal generated by the pulse wave measurement unit; and The vascular endothelial function evaluation unit evaluates the vascular endothelial function based on the calculated value of the peripheral blood pressure index from the time point when the blood drainage is released to the time when the evaluation time elapses.

2. The vascular endothelial function evaluation system according to claim 1, wherein: The vascular endothelial function evaluation unit evaluates the vascular endothelial function based on both the calculated value of the peripheral blood pressure index before blood drainage and the calculated value of the peripheral blood pressure index after blood drainage is released.

3. The vascular endothelial function evaluation system according to claim 1 or 2, wherein: It also includes a ring-shaped wearing member that is worn on a finger, The pulse wave sensor is mounted on the wearing member.

4. The vascular endothelial function evaluation system according to any one of claims 1 to 3, wherein: It also has a blood pressure cuff monitor. The pressurized area is pressurized by the cuff-type blood pressure monitor.

5. The vascular endothelial function evaluation system according to claim 4, wherein: The cuff-type blood pressure monitor and the pulse wave measurement unit have a function of wirelessly communicating with each other. The cuff-type blood pressure monitor notifies the pulse wave measurement unit of the timing of blood drainage and release, and the pulse wave measurement unit calculates the peripheral blood pressure index in synchronization with the timing of blood drainage and release of the cuff-type blood pressure monitor.

6. The vascular endothelial function evaluation system according to claim 4, wherein: It also has a control terminal, which has the function of wirelessly communicating with the cuff-type blood pressure monitor and the pulse wave measuring unit, controlling the blood expulsion and release actions of the cuff-type blood pressure monitor, and receiving a pulse wave signal from the pulse wave measuring unit and sending the pulse wave signal to the peripheral blood pressure index calculation unit.

7. The vascular endothelial function evaluation system according to any one of claims 1 to 6, wherein: The peripheral blood pressure index includes information on a peak value of an a-wave of an accelerated pulse wave obtained by second-order differentiation of a waveform of a pulse wave signal generated by the pulse wave measurement unit and an amplitude of a waveform of the pulse wave signal generated by the pulse wave measurement unit.

8. The vascular endothelial function evaluation system according to any one of claims 1 to 7, wherein: The peripheral blood pressure index includes information on a difference between a wave peak and d wave peak and a difference between a wave peak and b wave peak of an accelerated pulse wave obtained by second-order differentiation of the waveform of the pulse wave signal generated by the pulse wave measurement unit.

9. The vascular endothelial function evaluation system according to any one of claims 1 to 8, wherein: The peripheral blood pressure index includes information on the width of a peak that first appears in one beat of a velocity pulse wave obtained by first-order differentiation of a waveform of a pulse wave signal generated by the pulse wave measurement unit.

10. The vascular endothelial function evaluation system according to any one of claims 1 to 9, wherein: The vascular endothelial function evaluation unit further uses a temporal change in the amplitude of the pulse wave signal generated by the pulse wave measurement unit from a time point when the blood flow is released to a certain time point when evaluating the vascular endothelial function.

11. The vascular endothelial function evaluation system according to any one of claims 1 to 10, wherein: The pulse wave sensor is a photoelectric pulse wave sensor.

12. The vascular endothelial function evaluation system according to claim 11, wherein: The photoelectric pulse wave sensor uses light contained in the wavelength range from blue to yellow-green.

13. The vascular endothelial function evaluation system according to claim 12, wherein: The photoelectric pulse wave sensor includes a light emitting element and a light receiving element, wherein the light receiving element receives light emitted from the light emitting element and passing through a living tissue, and a distance between the light emitting element and the light receiving element is 1 mm or more and 3 mm or less.

14. The vascular endothelial function evaluation system according to any one of claims 1 to 13, wherein: The vascular endothelial function evaluation unit changes the evaluation time according to the blood flow time.

15. The vascular endothelial function evaluation system according to any one of claims 11 to 13, wherein: The photoelectric pulse wave sensor has the function of radiating light of at least two different wavelengths. The vascular endothelial function evaluation unit changes the evaluation time according to the wavelength of light used to acquire the pulse wave signal.

16. The vascular endothelial function evaluation system according to any one of claims 1 to 15, wherein: further comprising a reference pulse wave measuring unit for generating a reference pulse wave signal based on a measurement result of a reference pulse wave sensor installed at a position symmetrical to the installation position of the pulse wave sensor. The vascular endothelial function evaluation unit further uses the peripheral blood pressure index calculated based on the reference pulse wave signal generated by the reference pulse wave measurement unit when evaluating the vascular endothelial function.

17. A vascular endothelial function evaluation device, comprising: a pulse wave measuring device that generates a pulse wave signal based on a measurement result of a pulse wave sensor installed at a site farther from the heart than a pressurized site to be pressurized for blood removal; and A control terminal calculates a peripheral blood pressure index related to the steepness of the rise of each beat of the pulse wave signal generated by the pulse wave measuring device, evaluates the vascular endothelial function based on the calculated value of the peripheral blood pressure index from the time point when the expulsion blood is released to the time when the evaluation time has passed, and outputs the evaluation result.

18. A method for evaluating vascular endothelial function, comprising the following steps: A part of the body is pressurized to drive blood, and then released, and a pulse wave signal of an artery or capillary is obtained from a certain time from the time when the blood is released at a part farther from the heart than the pressurized part; Calculating the time variation of the peripheral blood pressure index related to the rising steepness of each beat of the acquired pulse wave signal; and The vascular endothelial function is evaluated based on the temporal changes in the peripheral blood pressure index.

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