JP2011200265A - Arteriosclerosis index measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure an arteriosclerosis index with a simple apparatus while reducing a burden imposed on a subject.SOLUTION: This arteriosclerosis index measuring apparatus includes: an arterial volume sensor 70 that is provided on a cuff 20 to be mounted on a measuring site and detects the volume of the artery at the measuring site; a cuff pressure control section 103 that regulates the cuff pressure by pressurization and depressurization; and an index detection section 104. The index detection section 104 calculates an arteriosclerosis index based on a hysteresis indicated by the arterial volume sequentially detected in a process of applying the cuff pressure at a predetermined speed, and the arterial volume sequentially detected in a process of depressurizing the cuff pressure at a predetermined speed after finishing the pressurizing process.

Description

  The present invention relates to an apparatus for measuring an index of arteriosclerosis, and more particularly to an arteriosclerosis index measuring apparatus for measuring an index of arteriosclerosis based on a change in arterial volume detected while compressing an artery from the outside.

  Arteriosclerosis in which the elasticity of the arterial wall is reduced is a cause of diseases such as cerebral infarction, cerebral hemorrhage, angina pectoris, and myocardial infarction. The arterial wall is hardened mainly with aging, but there are individual differences in blood vessel status even at the same age, so the progression rate varies depending on lifestyle habits such as diet, exercise, smoking, drinking, and stress. . Therefore, presentation of an arteriosclerosis index indicating the degree of arteriosclerosis has been desired for disease prevention.

  As a method for measuring arteriosclerosis that does not impose a burden on the body, a method for noninvasive measurement has been proposed. Pulse wave velocity,% FMD (Flow Mediated Dilation) and the like are used as arteriosclerosis indices by noninvasive measurement. In the method for measuring the pulse wave propagation velocity, a pulse wave is detected at two points away from the body, and an arteriosclerosis index is calculated by analyzing the detected pulse wave (Patent Document 1).

  In the examination of% FMD, the brachial artery is blocked for about 5 minutes, the blood vessel diameter before and after ischemia is measured, the increase rate of the blood vessel diameter is calculated based on the measurement result, and the calculated increase rate is taken as% FMD (Patent Document 2). ).

  A method for measuring bioimpedance has been proposed as a method for simply measuring the rate of increase in blood vessel diameter using the same principle as% FMD (Patent Document 3).

JP-A-6-189917 JP 2003-180690 A JP 2009-388 A

  In the method of Patent Document 1, the apparatus is complicated. In addition, a blood vessel image is used for measurement of the blood vessel diameter in Patent Document 2, and image acquisition and blood vessel diameter recognition are performed by a doctor's hand and eyes. For this reason, reproducibility is low between inspectors and between inspection facilities. In addition, the complexity of the apparatus and the inspection take time, and the burden on the subject is large. Further, in the measurement method using bioimpedance described in Patent Document 3, it takes a long time for the examination, so that the burden on the subject is large.

  SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an arteriosclerosis index measuring apparatus capable of measuring an arteriosclerosis index using a simple device and reducing a burden on a subject.

  According to one aspect of the present invention, an arteriosclerosis index measuring apparatus for measuring an index of arteriosclerosis includes a cuff attached to a measurement site, and pressure detection means for detecting a cuff pressure representing the pressure in the cuff. A volume detection means for detecting the volume of the artery at the measurement site, a cuff pressure adjusting means for adjusting the cuff pressure by pressurization and decompression, and an application for pressurizing the cuff pressure at a predetermined speed. Based on the hysteresis indicated by the volume of the arteries sequentially detected by the volume detection means in the pressure process and the volume of the arteries sequentially detected by the volume detection means in the decompression process of reducing the cuff pressure at a predetermined speed after the pressurization process is completed, Index calculation means for calculating an arteriosclerosis index.

  Preferably, a volume that detects and outputs an arterial volume signal indicating the volume and an arterial volume change signal indicating the change in the volume based on the volume of the artery sequentially detected by the volume detecting unit in accordance with the change in the cuff pressure. Signal detection means is further provided.

  Preferably, the index calculating means includes a value based on the arterial volume signal detected when the amplitude of the arterial volume change signal output from the volume signal detecting means in the pressurizing process indicates the maximum amplitude, and the volume signal in the depressurizing process. The arteriosclerosis index is calculated based on the difference from the value based on the arterial volume signal detected when the amplitude of the arterial volume change signal output from the detection means indicates the maximum amplitude.

  Preferably, the index calculating means includes a value based on an arterial volume signal output from the volume signal detecting means when the pressure detecting means detects a cuff pressure indicating a predetermined pressure in the pressurizing process, and a pressure detecting means in the depressurizing process. The arteriosclerosis index is calculated based on the difference from the value based on the arterial volume signal output by the volume signal detecting means when detecting the cuff pressure indicating the predetermined pressure.

  Preferably, the index calculating means includes a cuff pressure detected by the pressure detecting means when the value based on the arterial volume signal output from the volume signal detecting means indicates a predetermined value in the pressurizing process, and a volume in the depressurizing process. When the value based on the arterial volume signal output from the signal detection means indicates a predetermined value, the arteriosclerosis index is calculated based on the difference from the cuff pressure detected by the pressure detection means.

  Preferably, the index calculating means is a value based on the arterial volume signal output by the volume signal detecting means when the volume signal detecting means starts detecting an arterial volume change signal having an amplitude value equal to or greater than a threshold value in the pressurization process, When the volume signal detection means starts detecting an arterial volume change signal having an amplitude value less than the threshold value during the decompression process, the arteriosclerosis index is calculated based on the difference from the value based on the arterial volume signal output by the volume signal detection means. calculate.

  Preferably, the index calculating means is a value based on the arterial volume signal output by the volume signal detecting means when the volume signal detecting means starts detecting an arterial volume change signal having an amplitude value less than a threshold value during the pressurization process, When the volume signal detection means starts detecting an arterial volume change signal having an amplitude value greater than or equal to the threshold value during the decompression process, the arteriosclerosis index is calculated based on the difference from the value based on the arterial volume signal output by the volume signal detection means. calculate.

  Preferably, the index calculation means includes a value of an arterial volume signal that indicates that the artery has a maximum diameter based on the arterial volume signal detected by the volume signal detection means in the process in which the cuff pressure adjusting means changes the cuff pressure. A difference detection means for detecting a difference from the value of the arterial volume signal indicating that the artery is in an obstructed state, and the difference detection means detects the difference in order to calculate a normalized arteriosclerosis index Divide by the difference.

  Preferably, the index calculating means detects the arterial volume signal indicating that the value based on the arterial volume signal indicates a predetermined value from the time when the pressure detecting means detects the cuff pressure indicating the predetermined pressure in the pressurizing process. And the volume signal detecting means for detecting the arterial volume signal indicating that the value based on the arterial volume signal indicates a predetermined value from when the pressure detecting means detects the cuff pressure indicating the predetermined pressure in the decompression process. The arteriosclerosis index is calculated based on the difference from the time length until the detection.

  An arteriosclerosis index measurement program according to another aspect of the present invention is an arteriosclerosis index measurement program for measuring an arteriosclerosis index while changing a cuff pressure representing a pressure in a cuff attached to a measurement site. Adjusting the cuff pressure by pressurization and depressurization, the arterial volume sequentially detected during the pressurization process of pressurizing the cuff pressure at a predetermined speed, and reducing the cuff pressure at a predetermined speed after finishing the pressurization process And a step of calculating an arteriosclerosis index based on the hysteresis indicated by the volume of the artery sequentially detected during the decompression process.

  According to the present invention, the volume of the artery according to the change in the cuff pressure is sequentially detected and detected in each of the pressurization process in which the cuff pressure is increased at a predetermined speed and the depressurization process in which the cuff pressure is decreased at the predetermined speed after the pressurization process is completed. Since the arterial volume index hysteresis is quantified and used as an arteriosclerosis index, the arteriosclerosis index can be easily measured without providing a special mechanism and without long-term ischemia.

It is an external appearance perspective view of the electronic blood pressure monitor which concerns on each embodiment of this invention. It is a figure showing the concept which controls the cuff pressure in the electronic blood pressure monitor which concerns on each embodiment of this invention. It is a block diagram showing the hardware constitutions of the electronic blood pressure monitor which concerns on each embodiment of this invention. It is a flowchart which shows the measurement process in Embodiment 1 of this invention. It is a detection flowchart of ST5 (ST7) according to Embodiment 1 of the present invention. It is a detection flowchart of ST5 which concerns on Embodiment 2 of this invention. It is a detection flowchart of ST7 which concerns on Embodiment 2 of this invention. It is a detection flowchart of ST5 (ST7) according to Embodiment 3 of the present invention. It is a detection flowchart of ST5 (ST7) according to Embodiment 5 of the present invention. It is a detection flowchart of ST5 (ST7) according to Embodiment 6 of the present invention. It is a graph which shows the correlation with the arteriosclerosis parameter | index detected by this Embodiment 1, and a pulse wave velocity. It is a figure explaining difference (DELTA) V which concerns on Embodiment 1 of this invention. It is a figure explaining difference (DELTA) Pdse which concerns on Embodiment 2 of this invention. It is a figure explaining difference (DELTA) Pdes which concerns on Embodiment 3 of this invention. It is a figure explaining difference (DELTA) Pdc which concerns on Embodiment 4 of this invention. It is a figure explaining difference (DELTA) Pc which concerns on Embodiment 5 of this invention. (A) And (B) is a figure explaining difference (DELTA) T based on Embodiment 6 of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same reference numerals indicate the same or corresponding parts, and description thereof will not be repeated.

  The arteriosclerosis index measuring apparatus according to each embodiment is assumed to be mounted on an electronic sphygmomanometer having a blood pressure measurement function, but may be provided as an apparatus having only an arteriosclerosis index measurement function.

(Concept of measuring arteriosclerosis index)
Since the arterial wall is not a perfect elastic body, the trajectory of the arterial volume change detected in the process of pressurizing the artery does not coincide with the trajectory of the arterial volume change detected in the depressurization process after the pressurization. This is called arterial volume hysteresis. For example, when the degree of arteriosclerosis is low, the arterial wall has sufficient elasticity. Even if the artery is sufficiently compressed by pressurization to form a blood-blocking state (arterial occlusion state), the arterial wall quickly returns to its original state when the pressure is reduced. The blood vessels are fully dilated. As a result, the difference between the arterial volume during pressurization and the arterial volume during decompression is relatively large. When the degree of arteriosclerosis is high, the elasticity of the arterial wall is low, so it takes time for the arterial wall to return to the original state even if the pressure state changes from the reduced pressure state, and the blood vessels do not expand sufficiently. Therefore, the difference between the arterial volume during pressurization and the arterial volume during decompression is relatively small. Thus, even if pressure is applied / depressurized at the same speed, the mechanical characteristics due to the elasticity of the arterial wall are different, and therefore the arterial volume is different. Therefore, the degree of arteriosclerosis can be estimated based on changes in the arterial volume in each of the pressurization process and the decompression process.

(Embodiment 1)
<Appearance of device>
FIG. 1 is an external perspective view of an electronic blood pressure monitor 1 according to each embodiment of the present invention.

  Referring to FIG. 1, an electronic sphygmomanometer 1 includes a main body 10 and a cuff 20 that can be wound around the limb of a person to be measured. The main body 10 is attached to the cuff 20. On the surface of the main body 10, a display unit 40 made of, for example, liquid crystal and an operation unit 41 for receiving an instruction from the measurement subject are arranged. The operation unit 41 includes a plurality of switches.

  In the present embodiment, “limbs” represent portions of the upper limbs and lower limbs excluding their respective fingers. That is, the limb includes a part from the wrist to the base of the arm and a part from the ankle to the base of the foot. In the following description, it is assumed that the cuff 20 is attached to the wrist of the measurement subject. Here, an electronic sphygmomanometer of the type that wraps the cuff 20 around the extremities for measuring the arteriosclerosis index is illustrated, but an electronic sphygmomanometer of the type that wraps the cuff 20 around the finger may be used.

  As shown in FIG. 1, the electronic sphygmomanometer 1 in the present embodiment will be described by taking an example in which the main body 10 is attached to the cuff 20, but as used in an upper arm type sphygmomanometer, The main body 10 and the cuff 20 may be connected by an air tube (air tube 31 in FIG. 3 described later).

  FIG. 2 is a diagram showing the concept of controlling the cuff pressure in electronic blood pressure monitor 1 according to each embodiment of the present invention. FIG. 2 shows a state where the cuff 20 is attached to the wrist 200 of the measurement subject.

  Referring to FIG. 2, a cuff pressure adjusting mechanism including a pump 57 and an exhaust valve (hereinafter simply referred to as “valve”) 52 is disposed in the main body 10.

  The air system 30 including the pump 57, the valve 52, and the pressure sensor 32 for detecting the pressure (cuff pressure) in the air bladder 21 is connected to the air bladder 21 contained in the cuff 20 via the air tube 31. Is done. Thus, since the air system 30 is provided in the main body part 10, the thickness of the cuff 20 can be kept thin.

  Inside the air bladder 21, a light emitting element 71 and a light receiving element 72 are arranged at a predetermined interval. In the present embodiment, the light emitting element 71 and the light receiving element 72 are arranged along the circumference of the wrist when the cuff 20 is attached. However, the present invention is not limited to such an arrangement example.

(Hardware configuration)
FIG. 3 is a block diagram showing a hardware configuration of electronic blood pressure monitor 1.

  Referring to FIG. 3, cuff 20 of electronic sphygmomanometer 1 includes air bag 21 and arterial volume sensor 70. The arterial volume sensor 70 includes the light emitting element 71 and the light receiving element 72 described above. The light emitting element 71 emits light to the artery, and the light receiving element 72 receives the transmitted light or reflected light of the artery irradiated by the light emitting element 71.

  The arterial volume sensor 70 may be any sensor that can detect the arterial volume that changes due to a change in cuff pressure and pulsation, and may detect the arterial volume based on impedance. In that case, it replaces with the light emitting element 71 and the light receiving element 72, and the some electrode for detecting the impedance of the site | part containing an artery is contained.

  In addition to the display unit 40 and the operation unit 41 described above, the main unit 10 centrally controls each unit and performs various arithmetic processes, and a program that causes the CPU 100 to perform predetermined operations. And a memory unit 42 for storing various data, a non-volatile memory (for example, a flash memory) 43 for storing measured data, a power source 44 for supplying power to each unit via the CPU 100, and a current time And a timer 45 that outputs time measurement data to the CPU 100. The operation unit 41 includes a power switch 41A that receives an input of an instruction for turning on or off the power supply, a measurement switch 41B that receives an instruction to start measurement, a stop switch 41C that receives an instruction to stop measurement, and a nonvolatile switch Memory switch 41D for receiving an instruction to read data recorded in the memory 43.

  The main body 10 further includes the air system 30, the cuff pressure adjusting mechanism 50, the oscillation circuit 33, the light emitting element driving circuit 73, and the arterial volume detection circuit 74 described above.

  The adjustment mechanism 50 includes a pump 57, a valve 52, a pump drive circuit 53, and a valve drive circuit 54.

  The pump 57 supplies air to the air bladder 21 in order to increase the cuff pressure. The valve 52 is opened and closed to exhaust or seal the air in the air bladder 21. The pump drive circuit 53 controls the drive of the pump 57 based on a control signal given from the CPU 100. The valve drive circuit 54 performs opening / closing control of the valve 52 based on a control signal given from the CPU 100.

The light emitting element drive circuit 73 causes the light emitting element 71 to emit light at a predetermined timing in response to a command signal from the CPU 100. The arterial volume detection circuit 74 detects the arterial volume based on the signal from the light receiving element 72.
The arterial volume detection circuit 74 has an HPF (High Pass Filter) circuit (not shown). The arterial volume detection circuit 74 receives a volume pulse wave signal indicating a change in the volume of the artery from the arterial volume sensor 70. The volume pulse wave signal is a signal representing the pulse wave as a change in the intravascular volume accompanying the pulsation of the heart. It should be noted that the change in the intravascular volume can be regarded as a change in the amount of blood tissue in the blood vessel. In operation, the arterial volume detection circuit 74 outputs a volume pulse wave signal output from the arterial volume sensor 70 by using an HPF circuit and an arterial volume signal Pd indicating a DC component of the volume pulse wave signal and an arterial volume change signal indicating an AC component. Separated to Pa and output. For example, assuming that the filter constant is 1 Hz, a signal of 1 Hz or less is derived as a DC component, and a signal exceeding 1 Hz is derived as an AC component. The arterial volume change signal Pa indicates the amount of change in the volume of the artery at the measurement site, and more specifically, the amount of change is indicated by the amplitude value of the arterial volume change signal Pa. The arterial volume signal Pd may be detected by averaging the volume pulse wave signal for each beat.

  The pressure sensor 32 is a capacitance-type pressure sensor, and the capacitance value changes depending on the cuff pressure. The oscillation circuit 33 outputs an oscillation frequency signal corresponding to the capacitance value of the pressure sensor 32 to the CPU 100. The CPU 100 detects a cuff pressure by converting a signal obtained from the oscillation circuit 33 into a pressure.

<Functional configuration>
FIG. 3 also shows a functional configuration of the electronic sphygmomanometer 1 according to each embodiment of the present invention.

  Referring to FIG. 3, the CPU 100 includes a cuff pressure control unit 103 for controlling the cuff pressure, an index detection unit 104 for measuring an arteriosclerosis index, and a blood pressure measurement unit 108.

The cuff pressure control unit 103 variably controls the cuff pressure by driving the adjustment mechanism 50.
The index detection unit 104 detects a predetermined target value for detecting an arteriosclerosis index based on the volume pulse wave signal or the cuff pressure detected in the process of changing the cuff pressure, and changes the cuff pressure. Index calculation for calculating an arteriosclerosis index based on the detection results of the arterial volume detection unit 106, the target detection unit 105, and the arterial volume detection unit 106 that detect information on the arterial volume based on the volume pulse wave signal detected in the process Part 107 is included.

  The blood pressure measurement unit 108 includes a constant volume control unit 109 having a servo control unit 110 and a blood pressure determination unit 111 in order to continuously measure blood pressure by the volume compensation method.

(Blood pressure measurement method of blood pressure measurement unit 108)
The constant volume control unit 109 applies an external pressure to the artery at the measurement site from outside the living body when measuring the blood pressure by the volume compensation method, and obtains an optimal servo gain so that the in-vivo pressure (cuff pressure) and the intra-arterial pressure, that is, blood pressure are always balanced. decide. The servo controller 110 servo-controls the pump drive circuit 53 and the valve drive circuit 54 using the determined servo gain.

  That is, after the constant volume control unit 109 sets the cuff pressure to the initial cuff pressure (described later) via the cuff pressure control unit 103, the servo control unit 110 outputs the arterial volume signal output from the arterial volume detection circuit 74. The pump drive circuit 53 and the valve drive circuit 54 are servo-controlled so that Pd matches the control target value V0 detected by the target detection unit 105. Here, the control target value V0 indicates the arterial volume when the intra-arterial pressure and the in-vivo pressure are in equilibrium (the arterial wall is in an unloaded state). Therefore, the control target value V0 is also referred to as an equilibrium control target value V0.

  In the servo control, a servo gain corresponding to the control deviation is determined so as to maintain the arterial volume at the equilibrium control target value V0, and the pump drive circuit 53 and the control amount (voltage signal) according to the determined servo gain are used. The valve drive circuit 54 is feedback controlled. Thereby, the amount of fluid supplied / exhausted in the air bag 21 is controlled so as to maintain the above-described equilibrium state.

  Under such arterial volume constant control using servo control, the blood pressure determination unit 111 detects the extracorporeal pressure (that is, cuff pressure) detected via the pressure sensor 32 and the oscillation circuit 33, Blood pressure can be measured continuously.

  The blood pressure measurement method is not limited to the volume compensation method, and may be another measurement method such as an oscillometric method.

  The operation of each functional block included in the CPU 100 may be realized by executing software stored in the memory unit 42, and at least one of these functional blocks is realized by hardware. Also good. Alternatively, at least one of the blocks described as hardware (circuit) may be realized by the CPU 100 executing software stored in the memory unit 42.

  The flowcharts of FIGS. 4 to 10 to be described later showing processing using these function units are stored in advance in the memory unit 42 as a program, and the CPU 100 reads out and executes this program, thereby realizing the measurement processing function. Is done.

<Overall processing>
Next, the operation of the electronic sphygmomanometer 1 in the present embodiment will be described.

  FIG. 4 is a flowchart showing the measurement process in the first embodiment of the present invention. It is assumed that the person to be measured wears the cuff 20 of the electronic sphygmomanometer 1 on the wrist as the measurement site as shown in FIG. 2 when measuring blood pressure.

  Referring to FIG. 4, CPU 100 detects whether or not power switch 41A is operated (for example, pressed) (step ST (hereinafter simply referred to as ST) 1). If it is detected that the power switch 41A has been operated, the process proceeds to ST2.

  In ST2, the CPU 100 performs an initialization process. Specifically, a predetermined area of the memory unit 42 is initialized, the air in the air bladder 21 is exhausted, and the pressure sensor 32 is corrected.

  When initialization is completed, CPU 100 detects whether or not measurement switch 41B has been operated (for example, pressed) (ST3). Wait until the measurement switch 41B is operated. If it is detected that measurement switch 41B is pressed, the process proceeds to ST4.

  In the processes of ST4 to ST8, a process for detecting an arteriosclerosis finger index is executed. First, in ST4, the cuff pressure control unit 103 controls the valve drive circuit 54 and the pump drive circuit 53 in accordance with an instruction from the index detection unit 104. As a result, the valve 52 is closed and the pump 57 is driven so that the cuff pressure increases at a predetermined speed (for example, 5 mmHg / sec).

  The cuff pressure is gradually increased at a predetermined speed until a predetermined pressure (for example, maximum blood pressure (systolic blood pressure) +30 mmHg) for closing the artery at the measurement site is indicated. In such a pressurization process, the target detection unit 105 detects the initial cuff pressure and the equilibrium control target value V0 (ST5).

  When the pressurizing process is completed, the cuff pressure control unit 103 controls the adjustment mechanism 50 in accordance with an instruction from the index detection unit 104 in ST6. As a result, the pump 57 is stopped, and the valve 52 is set so as to decrease at the same predetermined speed (5 mmHg / sec) as the pressurization process until the cuff pressure indicates a predetermined pressure (for example, 0 mmHg) with the maximum diameter of the artery. Gradually opens. Alternatively, the pump 57 may be driven so that the cuff pressure decreases at a predetermined speed with the valve 52 closed.

  In the process of gradually decreasing the cuff pressure at a predetermined speed (decompression process), the target detection unit 105 detects the initial cuff pressure and the equilibrium control target value V0 (ST7).

  In the above-described process of changing the cuff pressure (pressurization process and decompression process), the arterial volume detection unit 106 determines the maximum value Pdmax and the minimum value of the arterial volume based on the arterial volume signal Pd sequentially input from the arterial volume detection circuit 74. Pdmin is detected.

  Details of detecting the initial cuff pressure and the equilibrium control target value V0 in the process of changing the cuff pressure will be described later. Here, the equilibrium control target value V0 detected in the pressurization process is called V0inf, and the equilibrium control target value V0 detected in the pressure reduction process is called V0def.

  After completing the decompression process, in ST8, the index calculation unit 107 uses the detected equilibrium control target values V0inf and V0def, and the maximum value Pdmax and the minimum value Pdmin of the arterial volume (Expression 1) and (Expression 2). Accordingly, the difference ΔV between the equilibrium control target value V0inf and V0def and the arteriosclerosis index ASIv0 are calculated.

ΔV = V0def−V0inf (Formula 1)
ASIv0 = ΔV / (Pdmax−Pdmin) (Expression 2)
When the arteriosclerosis index is calculated, in ST9, the blood pressure measurement unit 108 measures the blood pressure. In ST10, the CPU 100 associates the measured arteriosclerosis index ASIv0 with the blood pressure and stores it in a predetermined area of the nonvolatile memory 43 and outputs it via the display unit 40.

Thus, the measurement process of the arteriosclerosis index ASIv0 is completed.
FIG. 11 shows that the arteriosclerosis index ASIv0 measured in the present embodiment has a correlation with a pulse wave velocity baPWV, which is one type of well-known arteriosclerosis index. To do.

<V0 detection procedure>
FIG. 5 shows a flowchart for detecting the equilibrium control target value V0 in ST5 (ST7) according to the first embodiment. Referring to FIG. 5, the target detection unit 105 determines whether or not the amplitude of the arterial volume change signal Pa that is sequentially input is maximum in the process of changing the cuff pressure (pressurization process or decompression process). (ST101). When the amplitude is determined to be maximum (YES in ST101), the value (voltage value) of the input arterial volume signal Pd and the cuff pressure detected based on the output of the oscillation circuit 33 are associated with each other in a predetermined area of the memory unit 42 (ST102).

  Target detection unit 105 compares the cuff pressure with a predetermined pressure, and determines whether or not the cuff pressure indicates the predetermined pressure based on the comparison result (ST103). While it is determined that the predetermined pressure is not commanded, that is, it is determined that the cuff pressure is less than the predetermined pressure (NO in ST103), the cuff pressure control unit 103 changes the cuff pressure at the predetermined speed (increase / decrease). To control.

  Until the cuff pressure is determined to indicate a predetermined pressure, the (temporary) maximum value of the amplitude of the arterial volume change signal Pa is detected, and the cuff pressure is detected based on the input signal from the oscillation circuit 33. The detected temporary maximum value and the cuff pressure detected at that time are recorded in a predetermined area of the memory unit 42. The provisional maximum value and the cuff pressure may be overwritten and recorded each time the recorded (provisional) maximum value is updated.

  Until it is determined that the cuff pressure indicates a predetermined pressure (YES in ST103), the above operation is repeated (ST103).

  The above-mentioned predetermined pressure may be a cuff pressure for sufficiently occluding the artery during the pressurization process, and is a value sufficiently higher than the systolic blood pressure measured in advance for the subject (for example, the systolic phase). (Blood pressure + 30 mmHg). In the depressurization process, the predetermined pressure may be a cuff pressure in a state where the artery is sufficiently open (a state indicating the maximum diameter), for example, the cuff pressure may be 0 mmHg. Detection of the predetermined pressure in the decompression process may be performed by a method of confirming that the arterial volume change signal Pa has disappeared.

  The value finally recorded as the maximum value of the amplitude of the arterial volume change signal Pa in the memory unit 42 by the processing of FIG. 5 is determined as the equilibrium control target value V0inf in the pressurization process, and the equilibrium control is performed in the decompression process. The target value V0def is determined. The equilibrium control target values V0inf and V0def are referred to as control target values for servo control. Further, the cuff pressure detected when the amplitude of the arterial volume change signal Pa indicates the maximum value is determined as a reference cuff pressure, that is, an initial cuff pressure at the time of servo control.

  The blood pressure measurement unit 108 sets the cuff pressure to the initial cuff pressure read from the memory unit 42 at the start of blood pressure measurement, and then uses the equilibrium control target value V0inf or V0def read from the memory unit 42 as a control target value to measure blood pressure. Start servo control for.

  The difference ΔV between the equilibrium control target value V0inf and V0def will be described with reference to the graph of FIG. The horizontal axis of the graph of FIG. 12 shows the passage of time (sec) in the cuff pressure changing process, and the vertical axis shows the cuff pressure (mmHg) detected along with the passage of time and the value (voltage: V) of the arterial volume signal Pd. . The change in the cuff pressure is indicated by a broken line, and the change in the arterial volume signal Pd is indicated by a solid line.

  When the artery is in an equilibrium state (no load state), the change in the arterial volume is maximized with respect to the change in the cuff pressure (external pressure), that is, the amplitude of the arterial volume change signal Pa is maximized. Accordingly, as shown in FIG. 12, the target detection unit 105 determines the arterial volume signal Pd detected when the maximum amplitude of the arterial volume change signal Pa is detected in the pressurization process as the equilibrium control target value V0inf. The arterial volume signal Pd detected when the maximum amplitude of the arterial volume change signal Pa is detected in the decompression process is determined as the equilibrium control target value V0def.

  Here, there is an individual difference in the amount of change in the arterial volume signal Pd detected in the process in which the artery changes from the maximum diameter (the arterial volume is the maximum value Pdmax) to the occlusion state (the arterial volume is the minimum value Pdmin). It is desirable to detect the arteriosclerosis index with accuracy that does not vary between subjects, that is, to normalize it.

  There are individual differences in the value of the arterial volume signal Pd and Pdmin to Pdmax due to differences in individual biological characteristics such as the thickness of the blood vessel and the absorbance with respect to the infrared light output from the light emitting element 71. Therefore, even if the degree of arteriosclerosis is comparable, there is a difference in the magnitude of ΔV.

  Therefore, information on individual differences is excluded by standardizing by the difference between Pdmin (at the time of maximum vessel expansion) to Pdmax (a state in which the blood vessel is completely occluded). That is, the arterial volume signal Pd (Pdmin) detected when the cuff pressure at which the artery has the maximum diameter is 0 mmHg and the arterial volume change signal Pa at which the artery is considered to be occluded are detected. The difference in the arterial volume signal Pd (Pdmax) is calculated, and the difference ΔV is divided by the calculated difference (see (Equation 2)), thereby normalizing the arteriosclerosis index ASIv0. By normalization, it is possible to calculate the arteriosclerosis index ASIv0 excluding individual differences.

  In a person who is progressing atherosclerosis, the difference ΔV is small because the elasticity of the blood vessel wall is low, that is, the hysteresis is small. Therefore, it can be said that the arteriosclerosis degree is higher as the arteriosclerosis index ASIv0 is smaller (see FIG. 11). .

  FIG. 11 shows a graph of the correlation between the arteriosclerosis index ASIv0 detected by this embodiment and the pulse wave velocity baPWV (cm / sec). The vertical axis of the graph in FIG. 11 represents the value of the arteriosclerosis index ASIv0, and the horizontal axis represents the pulse wave velocity baPWV (cm / sec). The pulse wave propagation velocity baPWV is a kind of well-known arteriosclerosis index, and indicates the propagation velocity of the pulse wave between the upper arm and the ankle of the subject, and the larger the value, the lower the elasticity of the blood vessel wall. The inventors measured the arteriosclerosis index ASIv0 and the pulse wave velocity baPWV for a plurality of subjects, and the results are shown in the graph of FIG. As shown in the figure, it was found that both have a correlation (correlation coefficient R = 0.37). Therefore, according to the arteriosclerosis index ASIv0 measured in the present embodiment, an arteriosclerosis index can be presented.

  As described above, focusing on hysteresis, the calculation of the arteriosclerosis index is performed when the artery is set to the same predetermined state in the pressurization process at a predetermined speed and the decompression process at the predetermined speed. The calculation using the volume information is not limited to the calculation using the above-described unloaded arterial volume V0. For example, a calculation method according to the following (Embodiment 2) to (Embodiment 6) may be used.

(Embodiment 2)
In the present embodiment, an arterial volume signal Pds detected when the amplitude of the arterial volume change signal Pa begins to appear during the pressurization process, and detected when the amplitude of the arterial volume change signal Pa begins to disappear during the depressurization process. The arteriosclerosis index ASIac is calculated based on the arterial volume signal Pde, that is, based on the arterial volume signal Pd detected when the artery is set to the same predetermined state.

  The difference ΔPdse between the arterial volume signals Pds and Pde will be described with reference to the graph of FIG. The horizontal axis of the graph of FIG. 13 shows the passage of time (sec) in the cuff pressure changing process, and the vertical axis shows the cuff pressure (mmHg) and arterial volume signal Pd (voltage: V) detected with the passage of time. The change in the cuff pressure is indicated by a broken line, and the change in the arterial volume signal Pd is indicated by a solid line.

  After the start of pressurization in the pressurization process, the arterial volume signal Pd detected at the time when the detection of the amplitude of the arterial volume change signal Pa is started is determined as Pds, and the arterial volume change signal Pa is detected in the decompression process after the pressurization process ends. The arterial volume signal Pd detected at the time when the amplitude of the current starts to disappear (no longer detected) is determined as Pde. A difference ΔPdse between the detected arterial volume signals Pds and Pde is calculated. The arteriosclerosis index ASIas can be calculated according to (Equation 2) using the difference ΔPd instead of the difference ΔV. In the present embodiment also, the arterial volume signals Pdmin and Pdmax are detected as in the first embodiment.

(Embodiment 3)
In the present embodiment, an arterial volume signal Pde detected when the amplitude of the arterial volume change signal Pa begins to disappear during the pressurization process, and an arterial volume change signal Pa detected when the amplitude of the arterial volume change signal Pa begins to appear during the depressurization process. The arteriosclerosis index ASIae is calculated based on the arterial volume signal Pds, that is, based on the arterial volume signal Pd detected when the artery is set to the same predetermined state.

  The difference ΔPdes between the arterial volume signals Pde and Pds will be described with reference to the graph of FIG. The horizontal axis of the graph of FIG. 14 shows the passage of time (sec) in the cuff pressure changing process, and the vertical axis shows the cuff pressure (mmHg) and arterial volume signal Pd (voltage: V) detected with the passage of time. The change in the cuff pressure is indicated by a broken line, and the change in the arterial volume signal Pd is indicated by a solid line.

  After the start of pressurization in the cuff pressure pressurization process, the arterial volume signal Pd detected when the amplitude of the arterial volume change signal Pa begins to disappear (can no longer be detected) is determined as Pde, and the decompression after the pressurization process ends In the process, the arterial volume signal Pd detected when the amplitude of the arterial volume change signal Pa begins to appear (starts detection) is determined as Pds. A difference ΔPdes between the detected arterial volume signals Pde and Pds is calculated. The arteriosclerosis index ASIac can be calculated according to (Equation 2) using the difference ΔPdes in place of the difference ΔV. In the present embodiment also, the arterial volume signals Pdmin and Pdmax are detected as in the first embodiment.

(Embodiment 4)
Based on the correlation between the arterial volume and the cuff pressure, the arteriosclerosis index ASIpc is calculated. Specifically, the arterial volume signal Pd (arterial volume signals Pdinf and Pddef) detected when a common predetermined cuff pressure is detected in the pressurization process and the decompression process, that is, when the artery is set to a similar predetermined state. ) To calculate the arteriosclerosis index ASIpc. That is, even when the artery is compressed with a predetermined cuff pressure in each of the pressurization process and the decompression process (that is, when the artery is set to the same predetermined state), the arterial volume is not the same because of the hysteresis of the artery. Without any difference. The arteriosclerosis index can be calculated by paying attention to this difference.

  The difference ΔPdc between the arterial volume signals Pdinf and Pddef will be described with reference to the graph of FIG. The horizontal axis of the graph of FIG. 15 shows the passage of time (sec) in the cuff pressure changing process, and the vertical axis shows the cuff pressure (mmHg) and arterial volume signal Pd (voltage: V) detected with the passage of time. The change in the cuff pressure is indicated by a broken line, and the change in the arterial volume signal Pd is indicated by a solid line.

  After starting the pressurization in the cuff pressure increasing process, the arterial volume signal Pd detected when the cuff pressure indicates the predetermined cuff pressure is determined as Pdinf, and the cuff pressure is detected in the depressurizing process after the pressurizing process ends. The arterial volume signal Pd detected when the pressure is indicated is determined as Pddef. The difference ΔPdc between the detected arterial volume signals Pdinf and Pddef can be calculated, and the difference ΔPdc can be used in place of the difference ΔV to calculate the arteriosclerosis index ASIpc. In the present embodiment also, the arterial volume signals Pdmin and Pdmax are detected as in the first embodiment.

(Embodiment 5)
In the present embodiment, the arteriosclerosis index ASIdc is calculated based on the correlation between the arterial volume and the cuff pressure. Specifically, the arteriosclerosis index ASIdc is calculated based on the difference ΔPc between the cuff pressures Pcinf and Pcdef detected when a common predetermined arterial volume is detected in each of the pressurization process and the decompression process.

  The difference ΔPc between the cuff pressures Pcinf and Pcdef will be described with reference to the graph of FIG. The horizontal axis of the graph of FIG. 16 shows the passage of time (sec) in the cuff pressure changing process, and the vertical axis shows the cuff pressure (mmHg) detected as time passes and the arterial volume signal Pd (voltage: V). The change in the cuff pressure is indicated by a broken line, and the change in the arterial volume signal Pd is indicated by a solid line.

  The cuff pressure detected when the arterial volume signal Pd indicates a predetermined level (predetermined voltage) is started as the cuff pressure Pcinf after the pressurization is started in the pressurization process of the cuff pressure. The cuff pressure detected when the volume signal Pd indicates the predetermined level (predetermined voltage) is determined as the cuff pressure Pcdef. By calculating the difference ΔPc between the detected cuff pressures Pcinf and Pcdef and using the difference ΔPc instead of the difference ΔV, the arteriosclerosis index ASIdc can be calculated according to (Equation 2). In the present embodiment also, the arterial volume signals Pdmin and Pdmax are detected as in the first embodiment.

(Embodiment 6)
In the present embodiment, the arteriosclerosis index ASItm is calculated based on the correlation between the arterial volume and the cuff pressure. In other words, after the artery is compressed with the same cuff pressure in each of the pressurization process and the decompression process, the arterial volume after the elapse of a predetermined time is determined even if pressurization / decompression is performed at a predetermined speed as described above. Because of the hysteresis, they are not the same but different. The arteriosclerosis index can be calculated by paying attention to this difference.

  Specifically, based on the difference ΔT in the required time from the detection of a common predetermined cuff pressure in the pressurization process and the decompression process to the detection of the arterial volume signal Pd at a predetermined level (predetermined voltage value). The arteriosclerosis index ASItm is calculated.

  The difference ΔT in required time will be described with reference to the graph of FIG. The horizontal axis of the graph of FIG. 17 shows the passage of time (sec) in the cuff pressure changing process, and the vertical axis shows the cuff pressure (mmHg) and arterial volume signal Pd (voltage: V) detected with the passage of time. The change in the cuff pressure is indicated by a broken line, and the change in the arterial volume signal Pd is indicated by a solid line. FIG. 17B is an enlarged view of a part of FIG. 17A for explanation.

  After the start of pressurization in the pressurization process, a required time Tinf, which is the length of time from when the predetermined cuff pressure is detected to when the arterial volume signal Pd having a predetermined value is detected, is detected, and the decompression process after the pressurization process ends The required time Tdef which is the length of time from when the predetermined cuff pressure is detected to when the predetermined arterial volume signal Pd is detected is detected. A difference ΔT between the detected required times Tinf and Tdef is calculated, and an arteriosclerosis index ASItm is calculated according to (Equation 2) using the difference ΔT instead of the difference ΔV. In the present embodiment also, the arterial volume signals Pdmin and Pdmax are detected as in the first embodiment.

Next, the detection processing flow according to (Embodiment 2) to (Embodiment 6) will be described.
(Processing flow of Embodiment 2)
The overall processing of the present embodiment is the same as that of FIG. 4 except for the processing of ST5 and ST7, and the description thereof is omitted. The process of ST5 is replaced with the process of FIG. 6, and the process of ST7 is replaced with the process of FIG.

  The detection flow of the arterial volume signal Pds in ST5 will be described with reference to FIG. First, the index detection unit 104 determines whether a pulse wave is detected based on a pulse wave detection flag that is a temporary variable (ST201). The pulse wave detection flag is set to an initial value (OFF) in the initialization process (ST2).

  The pulse wave detection flag is updated to ON only when the amplitude of the arterial volume change signal Pa is detected in the process of changing the cuff pressure. Therefore, it instructs OFF until it is detected.

  Thereafter, the target detection unit 105 compares the amplitude value of the arterial volume change signal Pa detected by the arterial volume detection unit 106 with a threshold value, and determines whether or not the condition (amplitude value ≧ threshold value) is satisfied based on the comparison result. Determine (ST202).

  If it is determined that the condition is satisfied, it is determined that the amplitude of the arterial volume change signal Pa equal to or greater than the threshold value, that is, a pulse wave is detected (YES in ST202), and the arterial volume signal Pd ( The value of the arterial volume signal Pds) and the cuff pressure are associated with each other and stored in the memory unit 42, and the pulse wave detection flag is updated to ON (ST203). Thereafter, in ST204, it is determined whether or not the cuff pressure indicates a predetermined target value in the pressurization (decompression) process. If it is determined to be instructed (YES in ST204), the series of processes ends, but if it is determined not to be instructed (NO in ST204), the process returns to ST201, and the subsequent processes are similarly repeated.

  If it is determined that the condition is not satisfied, it is determined that the amplitude of the arterial volume change signal Pa has not been detected, that is, the pulse wave has not been detected yet (NO in ST202), and the process proceeds to ST204.

  Thereby, when the cuff pressure indicates a predetermined target value (systolic blood pressure + 30 mmHg in the pressurization process, 0 mmHg in the depressurization process), the value of the arterial volume signal Pds is stored in the memory unit 42.

  With reference to FIG. 7, the detection flow of the arterial volume signal Pde in ST7 will be described. First, the index detection unit 104 determines whether or not the pulse wave has disappeared based on the pulse wave disappearance flag that is a temporary variable (ST301). The pulse wave disappearance flag is set to an initial value (OFF) in the initialization process (ST2). The pulse wave disappearance flag is updated to ON only when the amplitude of the arterial volume change signal Pa begins to disappear in the process of changing the cuff pressure. Therefore, it is instructed to turn OFF until it disappears.

  Thereafter, the target detection unit 105 compares the amplitude value of the arterial volume change signal Pa detected by the arterial volume detection unit 106 with a threshold value, and determines whether or not the condition (amplitude value ≧ threshold value) is satisfied based on the comparison result. Determine (ST302).

  If it is determined that the condition is not satisfied, it is determined that the amplitude value of the arterial volume change signal Pa less than the threshold is detected, that is, the pulse wave has not disappeared (NO in ST302), and the process proceeds to ST304. To do. If it is determined that the condition is not satisfied, it is determined that the amplitude of the arterial volume change signal Pa has not been detected, that is, the pulse wave has disappeared (NO in ST302), and the arterial volume signal Pd ( The value of the arterial volume signal Pde) and the cuff pressure are stored in association in the memory unit 42, and the pulse wave disappearance flag is updated to ON (ST303). Thereafter, in ST304, it is determined whether or not the cuff pressure indicates a predetermined target value. If it is determined to be instructed (YES in ST304), a series of processing ends, but if it is determined not to be instructed (NO in ST304), the processing returns to ST301, and the subsequent processing is similarly repeated.

  Thus, when the cuff pressure indicates a predetermined target value (systolic blood pressure +30 mmHg in the pressurization process, 0 mmHg in the depressurization process), the value of the arterial volume signal Pde is stored in the memory unit 42.

(Processing flow of Embodiment 3)
The overall processing of the present embodiment is the same as that of FIG. 4 except for the processing of ST5 and ST7, and the description thereof is omitted. The process of ST5 is replaced with the process of FIG. 7, and the process of ST7 is replaced with the process of FIG. The processing in FIGS. 6 and 7 is as described above.

(Processing flow of Embodiment 4)
The overall processing of the present embodiment is the same as that of FIG. 4 except for the processing of ST5 and ST7, and the description thereof is omitted. The processing of ST5 and ST7 is replaced with the processing of FIG.

  A procedure for detecting the arterial volume signal Pdinf will be described with reference to FIG. The target detection unit 105 detects the cuff pressure in the pressurization process, and compares the detected cuff pressure with a predetermined cuff pressure. If it is determined that the predetermined cuff pressure is not instructed based on the comparison result (NO in ST401), the process proceeds to ST403, but if it is determined to be instructed (YES in ST401), the arterial volume detection is performed at that time. The arterial volume signal Pd detected by the unit 106 is stored in the memory unit 42 as the arterial volume signal Pdinf (ST402). Thereafter, the detected cuff pressure is compared with a predetermined pressurization target value (ST403), and when the detected cuff pressure indicates the pressurization target value (systolic blood pressure + 30 mmHg) based on the comparison result (YES in ST403), The memory unit 42 stores the value of the arterial volume signal Pdinf.

  If it is determined that the pressurization target value is not instructed (NO in ST403), the process returns to ST401, and the subsequent processes are similarly performed.

  Even in the decompression process, the arterial volume signal Pddef can be detected according to the procedure of FIG. In this case, in ST403, the predetermined pressure reduction target value compared with the detected cuff pressure is 0 mmHg, and finally the value of the arterial volume signal Pddef is stored in the memory unit 42. Other processing is as described above.

  Note that the predetermined cuff pressure referred to in ST401 of FIG. 8 may be a predetermined value or detected by the equilibrium control target value V0 of the first embodiment and the arterial volume signal Pds (Pde) of the second embodiment. It may be the cuff pressure detected at the time of being performed.

(Processing flow of Embodiment 5)
The overall processing of the present embodiment is the same as that of FIG. 4 except for the processing of ST5 and ST7, and the description thereof is omitted. The processing of ST5 and ST7 is replaced with the processing of FIG.

  The procedure for detecting the cuff pressure Pcinf will be described with reference to FIG. The target detection unit 105 compares the value of the arterial volume signal Pd detected by the arterial volume detection unit 106 during the pressurization process with a predetermined value. If it is determined that the value of the detected arterial volume signal Pd does not indicate a predetermined value based on the comparison result (NO in ST501), the process proceeds to ST503. If it is determined that the value of the detected arterial volume signal Pd indicates a predetermined value based on the comparison result (YES in ST501), the cuff pressure detected at that time is stored in the memory unit 42 as the cuff pressure Pcinf (ST502). Thereafter, the detected cuff pressure is compared with a predetermined pressurization target value (systolic blood pressure + 30 mmHg), and it is determined whether the detected cuff pressure indicates the pressurization target value based on the comparison result (ST503).

  If it is determined that the pressurization target value is not instructed (NO in ST503), the process returns to ST401, and the subsequent processes are performed in the same manner. However, if it is determined to be instructed (YES in ST503), the series of processes ends. .

  The procedure for detecting the cuff pressure Pcdef is also executed by the procedure shown in FIG. 8 in the decompression process, and the arterial volume signal Pd detected when the detected cuff pressure is determined to indicate a predetermined cuff pressure (0 mmHg) is And stored in the memory unit 42 as the arterial volume signal Pddef.

  The predetermined value referred to in the process of pressurizing (depressurizing) the arterial volume signal Pd referred to in ST501 of FIG. 9 may be a predetermined value or the equilibrium control target value V0 of the first embodiment. It may be the value of the arterial volume signal Pds (Pde) of form 2.

(Processing flow of Embodiment 6)
The overall processing of the present embodiment is the same as that of FIG. 4 except for the processing of ST5 and ST7, and the description thereof is omitted. The processing of ST5 and ST7 is replaced with the processing of FIG.

The procedure for detecting the required time Tinf in the pressurizing process will be described with reference to FIG.
Target detection unit 105 compares the cuff pressure detected in the pressurization process with a predetermined cuff pressure, and determines whether the cuff pressure indicates a predetermined cuff pressure based on the comparison result (ST601).

  If it is determined that the predetermined cuff pressure is instructed (YES in ST601), target detection unit 105 uses timer 45 to update (increment) the value of the timer counter by a predetermined value (for example, +1) (ST602). The timer counter indicates a temporary variable, and it is assumed that an initial value (for example, 0) is set before the processing of FIG. 10 is started.

  The target detection unit 105 compares the value of the arterial volume signal Pd detected by the arterial volume detection unit 106 with a predetermined value, and determines whether the arterial volume signal Pd indicates a predetermined value based on the comparison result ( ST603). If it is determined that a predetermined value is instructed (YES in ST603), the value of the timer counter is stored as a required time Tinf in a predetermined area of the memory unit 42 (ST604), but while it is determined not to be instructed (NO in ST603) ), The process returns to ST602, and the value of the timer counter is updated.

  The procedure for detecting the required time Tdef in the depressurization process is the same as the procedure shown in FIG. 10 in the depressurization process, and the value of the timer counter when it is determined that the arterial volume signal Pd indicates a predetermined value is the required time Tdef. Is stored in a predetermined area of the memory unit 42.

  The predetermined values of the predetermined cuff pressure and the arterial volume signal Pd referred to in FIG. 10 may be values determined in advance, the equilibrium control target value V0 detected in the pressurization process (or the depressurization process), and the arterial volume signal Pds. The value of (or Pde) may be used.

  In FIG. 17, using the arterial volume signal Pds detected in the pressurization process and the cuff pressure Pcs detected at that time, the time until the detected cuff pressure becomes the cuff pressure Pcs and then becomes the arterial volume signal Pds is shown. An example of measurement is shown. In this case, the required time Tinf detected in the pressurizing process is 0, and ΔT = the required time Tdef.

  As described above, for the arteriosclerosis index of (Embodiment 2) to (Embodiment 6), the balance control target value V0 in (Equation 1) is replaced with the value detected in each embodiment, and the difference is obtained. Can be calculated by normalizing the calculated difference according to (Equation 2).

  However, since the arteriosclerosis indices ASIdc and ASItm are not values that are influenced by individual differences in the arterial volume signal variation, normalization according to (Equation 2) is not required. Therefore, the value calculated according to (Equation 1) may be used as an arteriosclerosis index as it is. Even when these are used, when arteriosclerosis is in progress, the hysteresis of the arterial volume under pressure and pressure reduction increases.

Although the method for calculating the arteriosclerosis index from the difference is shown here, it is only necessary to quantify the arterial volume hysteresis due to pressurization and decompression, and a method using the ratio of measured values as shown in (Equation 3) is also possible. . ASIv0 = V0def / V0inf (Expression 3)
In addition, the measuring method of the arteriosclerosis parameter | index of each embodiment can also be provided as a program. Such a program is recorded on an optical medium such as a CD-ROM (Compact Disc-ROM) or a computer-readable non-transitory recording medium such as a memory card and provided as a program product. You can also. A program can also be provided by downloading via a network.

  The program according to the present invention is a program module that is provided as a part of a computer operating system (OS) and calls necessary modules in a predetermined arrangement at a predetermined timing to execute processing. Also good. In that case, the program itself does not include the module, and the process is executed in cooperation with the OS. A program that does not include such a module can also be included in the program according to the present invention.

  The program according to the present invention may be provided by being incorporated in a part of another program. Even in this case, the program itself does not include the module included in the other program, and the process is executed in cooperation with the other program. Such a program incorporated in another program can also be included in the program according to the present invention.

  The provided program product is installed in a program storage unit such as a hard disk and executed. Note that the program product includes the program itself and a storage medium in which the program is stored.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  20 cuff, 70 arterial volume sensor, 103 cuff pressure control unit, 104 index detection unit, 105 target detection unit, 106 arterial volume detection unit, 107 index calculation unit, 108 blood pressure measurement unit.

Claims (10)

An arteriosclerosis index measuring device for measuring an index of arteriosclerosis,
A cuff attached to the measurement site;
Pressure detecting means for detecting a cuff pressure representing the pressure in the cuff;
A volume detecting means provided on the cuff for detecting the volume of the artery of the measurement site;
Cuff pressure adjusting means for adjusting the cuff pressure by pressurization and decompression;
The volume of the artery sequentially detected by the volume detecting means in the pressurizing process for pressurizing the cuff pressure at a predetermined speed, and the volume detecting means in the depressurizing process for reducing the cuff pressure at the predetermined speed after the pressurizing process is finished. An arteriosclerosis index measuring device, comprising: an index measuring means for measuring an arteriosclerosis index based on the hysteresis indicated by the arterial volume detected sequentially.   Volume signal detection for detecting and outputting an arterial volume signal indicating the volume and an arterial volume change signal indicating the change of the volume based on the volume of the artery sequentially detected by the volume detecting means in accordance with the change of the cuff pressure The arteriosclerosis index measuring device according to claim 1, further comprising means. The indicator measuring means is
A value based on the arterial volume signal detected when the amplitude of the arterial volume change signal output from the volume signal detecting means in the pressurizing process indicates a maximum amplitude, and the volume signal detecting means in the depressurizing process. The arteriosclerosis according to claim 2, wherein the arteriosclerosis index is calculated based on a difference from a value based on the arterial volume signal detected when the amplitude of the arterial volume change signal output by A indicates a maximum amplitude. Indicator measuring device. The indicator measuring means is
In the pressurization process, when the pressure detection means detects the cuff pressure indicating a predetermined pressure, a value based on the arterial volume signal output by the volume signal detection means, and in the pressure reduction process, the pressure detection means The artery according to claim 2, wherein the arteriosclerosis index is calculated based on a difference from a value based on the arterial volume signal output by the volume signal detecting means when detecting the cuff pressure indicating the predetermined pressure. Curing index measuring device. The indicator measuring means is
The cuff pressure detected by the pressure detecting means when the value based on the arterial volume signal output from the volume signal detecting means in the pressurizing process indicates a predetermined value, and the volume signal detecting in the depressurizing process. The arteriosclerosis index is calculated based on a difference from a cuff pressure detected by the pressure detection means when a value based on the arterial volume signal output by the means indicates the predetermined value. Apparatus for measuring arteriosclerosis. The indicator measuring means is
A value based on the arterial volume signal output by the volume signal detecting means when the volume signal detecting means starts detecting the arterial volume change signal having an amplitude value greater than or equal to a threshold value in the pressurizing process; And when the volume signal detection means starts detecting the arterial volume change signal having an amplitude value less than the threshold, based on the difference from the value based on the arterial volume signal output by the volume signal detection means, The arteriosclerosis index measuring apparatus according to claim 2, wherein the arteriosclerosis index is calculated. The indicator measuring means is
A value based on the arterial volume signal output by the volume signal detecting means when the volume signal detecting means starts detecting the arterial volume change signal having an amplitude value less than a threshold value in the pressurizing process; And when the volume signal detection means starts detecting the arterial volume change signal having an amplitude value equal to or greater than the threshold, based on the difference from the value based on the arterial volume signal output by the volume signal detection means, The arteriosclerosis index measuring apparatus according to claim 2, wherein the arteriosclerosis index is calculated. The indicator measuring means is
In the process of changing the cuff pressure by the cuff pressure adjusting means, based on the arterial volume signal detected by the volume signal detecting means, the value of the arterial volume signal indicating that the artery is the maximum diameter, and the artery is occluded A difference detecting means for detecting a difference from the value of the arterial volume signal indicating that the state is a state,
The arteriosclerosis index measuring apparatus according to any one of claims 3 to 7, wherein the difference is divided by the difference detected by the difference detecting means in order to calculate the normalized arteriosclerosis index. The indicator measuring means is
In the pressurization process, from when the pressure detection means detects a cuff pressure indicating a predetermined pressure, until the volume signal detection means detects the arterial volume signal in which a value based on the arterial volume signal indicates a predetermined value And the arterial volume signal indicating that the value based on the arterial volume signal indicates the predetermined value from when the pressure detecting means detects the cuff pressure indicating the predetermined pressure in the decompression process. The arteriosclerosis index measuring apparatus according to claim 2, wherein the arteriosclerosis index is calculated based on a difference from a time length until detection by the detection unit. An arteriosclerosis index measurement program for measuring an index of arteriosclerosis while changing the cuff pressure representing the pressure in the cuff attached to the measurement site,
Adjusting the cuff pressure by pressurization and decompression;
The volume of the artery sequentially detected in the pressurizing process for increasing the cuff pressure at a predetermined speed, and the volume of the artery sequentially detected in the depressurizing process for decreasing the cuff pressure at the predetermined speed after the pressurizing process is completed. And a step of calculating an arteriosclerosis index based on the hysteresis shown in FIG.

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