JPH06261870A - Pulse wave analyzer, pulse wave sensor and pulse wave detector - Google Patents

Abstract

PURPOSE:To simultaneously execute measurement by a sensor and diagnosis based on the tactile sense of a diagnosing person and to measure a circulating kinelic parameter without damaging the patient's body as well. CONSTITUTION:A microcomputer 4 detects the radial arterial waves of the patient via the pulse wave detector 1 and executes the simulation based on the radial arterial wave form i.e., the processing to as well join the values of the respective elements of electric circuits simulating the system from the central part to the peripheral part of the artery system of the human body in such a manner that the response waveforms when the electric signals corresponding to the pressure waves of the aorta origin part coincide with the radial arterial waves. The values of the respective elements obtd. by such joining is outputted as the circulating constituted of thin rubber globes and a thin strain gage adhered to the rubber globes and, therefore, the diagnosing person is able to simultaneously make the diagnosis based on its own tactile sensor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulse wave evaluation device, pulse wave sensor and pulse wave detection device suitable for use in pulse diagnosis.

[0002]

2. Description of the Related Art When diagnosing a condition of the circulatory system, blood pressure and heart rate are most commonly measured. However, in order to make a more detailed diagnosis, it is necessary to measure hemodynamic parameters such as viscous resistance and compliance (viscoelasticity) of blood vessels. Conventionally, in order to measure such hemodynamic parameters, it is necessary to measure the pressure waveform and blood flow at the aortic root and notch, and the measurement method is to insert a catheter into the artery and measure directly. There was a method of doing it or a method of measuring indirectly with ultrasonic waves.

On the other hand, in Chinese medicine, there is known a method (a mouthpiece method) in which a diagnostician's finger is pressed against the subject's arm at three points (dimension, seki, and scale) along the radial artery to perform pulse diagnosis. Has been. Further, a pulsing device that automatically makes a diagnosis by the sulcus method using a piezoelectric element has also been proposed (Japanese Patent Publication No. S57-57).
-52054). Further, there is also known a technique of pressing the piezoelectric element by air pressure so as to make the pressing force of these piezoelectric elements uniform (Japanese Patent Laid-Open No. 4-9139).

[0004]

However, the method of inserting a catheter into an artery has a problem that an invasive and large-scale device is required. On the other hand, according to the method of indirectly measuring the hemodynamic parameter with ultrasonic waves, the blood flow in the blood vessel can be observed non-invasively,
This method requires skill and there is a problem in that an apparatus for measurement becomes large-scale.

On the other hand, in the pulse diagnostic device disclosed in Japanese Patent Publication No. 57-52054 or Japanese Patent Laid-Open No. 4-9139, it is possible to simply measure the pulse wave, but based on the measurement result. It is not possible to obtain hemodynamic parameters. Furthermore, these pulsing devices have a problem in that it is impossible to simultaneously perform measurement by a sensor and diagnosis based on the sense of touch of a diagnostician.

The present invention has been made in view of the above-mentioned circumstances, and it is an object of the present invention to provide a pulse wave analyzer having an inexpensive structure and capable of non-invasively evaluating hemodynamic parameters. The purpose of 1. A second object of the present invention is to provide a pulse wave sensor capable of simultaneously performing measurement by a sensor and diagnosis based on the sense of touch of a diagnostician, and pulse wave detection suitable for use in this pulse wave sensor. A third object is to provide a device.

[0007]

In order to solve the above-mentioned problems, in the structure according to claim 1, a plurality of pulse wave sensors for detecting a radial artery wave of a subject and a central part of an arterial system of a human body. Is a means for calculating the value of each element of an electric circuit simulating a system from the peripheral part to the peripheral part, and an output signal waveform obtained from the electric circuit when an electric signal corresponding to a pressure wave at the aortic origin is given Is an evaluation means for calculating the value of each element of the electric circuit so that the waveform becomes a waveform corresponding to the radial artery wave.

Further, in the structure according to claim 2,
It is characterized by comprising a thin film member attached to a finger of an examiner and a thin pressure detecting means fixed to the thin film member.

Further, in the structure according to claim 3,
A pulse wave sensor composed of a thin film member attached to the examiner's finger and a thin pressure detecting means fixed to the thin film member, and a direct current component detecting means for detecting a direct current component from the detection signal of the pulse wave sensor. An alternating current component detecting means for detecting an alternating current component from a detection signal of the pulse wave sensor, a storing means for appropriately storing a detection result in the direct current component detecting means, data stored in the storing means and the direct current component detecting means And a subtraction unit that outputs a difference from the detection result in.

[0010]

According to the structure of claim 1, when the pulse wave sensor detects a plurality of radial artery waves of the subject, the value of each element of the electric circuit is calculated by the evaluating means, and the circulatory dynamics of the subject is thereby calculated. Parameters are calculated.

Further, in the structure according to claim 2,
The examiner puts the thin film member on the finger and presses the finger along the pulse of the subject. As a result, the detection signal corresponding to the pulse wave is obtained from the detection means. Furthermore, since the pulse wave is propagated to the fingertips of the examiner through the thin film member, the examiner makes a diagnosis based on his or her sense of touch.

Further, in the structure according to claim 3,
The DC component detection means and the AC component detection means detect the DC component and the AC component of the detection signal of the pulse wave sensor. When the examiner wears the pulse wave sensor on the finger, the examiner stores the detection result of the DC component detecting means in the storage means. Next, when a finger is pressed along the pulse of the subject, a detection signal corresponding to the pulse wave is obtained from the alternating-current component detection means,
A signal corresponding to the pressing force of the finger is obtained from the DC component detecting means.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. <Structure of Embodiment> FIG. 1 is a block diagram showing the structure of a pulse wave analyzer according to an embodiment of the present invention. This device
Based on the information obtained from the human body by a non-invasive sensor, the hemodynamic parameters of the human arterial system are evaluated. The specific contents of the hemodynamic parameters handled in this example will be described later.

In FIG. 1, 1 is a pulse wave detecting device, and 2 is 1.
It is a stroke volume measuring device. Of these, the pulse wave detection device 1
As shown in FIG. 2, the pulse wave sensor S1 attached to the hand of the diagnostician detects the radial artery waveform and the blood pressure of the subject is detected via the cuff band S2 attached to the upper arm of the subject. To do. Then, the radial artery waveform is calibrated with the blood pressure, and the calibrated radial artery waveform obtained as a result is output as an electric signal (analog signal).

The analog signal output from the pulse wave detecting device 1 is input to the A / D converter 3 and converted into a digital signal at every predetermined sampling period. Further, the stroke volume measuring device 2 is connected to the cuff band S2 as shown in FIG. 2, and is the amount of blood discharged from the heart at one beat through the cuff band S2. The stroke volume is measured, and the measurement result is output as stroke volume data (digital signal). As this type of stroke volume measuring device 2, a device for measuring by the so-called systolic area method can be used.

Here, details of the pulse wave sensor S1 will be described with reference to FIG. In the figure, 51 is a rubber glove for surgery, and strain gauges 52 to 54 are adhered to the finger pad of each first segment of the second, third and fourth fingers. The strain gauges 52 to 54 are thin gauges, and the gauge rate is "170",
The resistance is “2 kΩ”, the width is “0.5 mm”, and the length is “4 mm”. Each strain gauge 52-54 is "4 mm x 11 mm"
Is fixed on the flexible thin plate base and is bonded to the rubber gloves 51 together with the thin film base.

Next, the configuration of the pulse wave detecting device 1 will be described with reference to FIG. In the figure, 68 is a known blood pressure monitor, which measures and outputs the blood pressure of the subject through the cuff band S2. A constant current source 61 supplies a constant current to the strain gauge 52. As a result, a voltage V _g according to the physical strain is generated at both ends of the strain gauge 52. This voltage V _g is D
It is amplified through the C amplifier 62 and supplied to the DC cutoff circuit 63 and the averaging circuit 65. Here, the DC amplifier 62
The voltage output from can be expressed as “V ₀ + V _d + ΔV”. Here, the voltage V ₀ is a voltage generated when the diagnostician puts on the rubber glove 51, and the voltage V 0
_d is the voltage generated by the pressing force when the diagnostician's finger is pressed against the subject's arm. The voltage ΔV is an AC voltage generated by the pulse pressure of the subject.

In the DC cutoff circuit 63, the voltage V ₀ ,
The former two of V _d and ΔV which are direct current components are removed,
A voltage ΔV which is an AC component, that is, a pulse wave signal is output.
This pulse wave signal is supplied to the microcomputer 4 through the A / D converter 3 after noise is removed through the low-frequency cutoff filter 64 having a cutoff frequency of “20 Hz”. On the other hand, in the averaging circuit 65, the voltage (V ₀ + V _d
The maximum value of + ΔV) is detected, and the voltage (V ₀ + V _d + ΔV) is averaged over several cycles, with one cycle from the occurrence of one maximum value to the occurrence of the next maximum value. As a result, the voltage ΔV that is the AC component is removed, and the voltage (V ₀ + V _d ) that is the DC component is output. Reference numeral 66 is a level storage circuit, which stores the output voltage level of the averaging circuit 65 at that time when the switch 66a is pressed, and continuously outputs the voltage of the stored level thereafter. Further, 67 is a subtracter, which subtracts the output voltage of the level storage circuit 66 from the output voltage of the averaging circuit 65 and outputs the subtraction result.

In the configuration of FIG. 16, when the diagnostician wears the rubber gloves 51, the DC amplifier 62 outputs the voltage V ₀ . When the switch 66a is pressed in this state, the voltage V ₀ is stored in the level storage circuit 66. Next, when the fingertip is pressed against the subject's arm while wearing the rubber gloves 51, the voltage (V ₀ + V _d ) is output from the averaging circuit 65, and the voltage corresponding to the pressing force is output via the subtractor 67. V _d
Is output. At the same time, the DC cutoff circuit 6
3. The voltage ΔV corresponding to the pulse wave is output through the low-frequency cutoff filter 64 sequentially. Further, since the pulse wave sensor S1 is composed of the thin rubber gloves 51 and the strain gauges 52 to 54, the diagnostician can simultaneously make a diagnosis based on his or her sense of touch. Note that the above components 61 to 67
Is provided in correspondence with the strain gauge 52,
Similar items are provided corresponding to the strain gauges 53 and 54.

The microcomputer 4 has a keyboard 5
Each process listed below is performed according to the command input from. Pulse wave reading process for loading the time-series digital signal of the radial artery waveform obtained via the A / D converter 3 into the built-in waveform memory. Averaging process for averaging a radial artery waveform corresponding to one beat Process for taking in stroke volume data Obtaining a mathematical expression representing the radial artery waveform corresponding to one beat
Parameter calculation processing for calculating each parameter of the electrical model corresponding to the subject's arterial system based on this mathematical expression The parameters obtained by the parameter calculation processing are used as circulatory dynamic parameters via an output device (for example, printer, display device, etc.) not shown. Output processing for outputting as described above The details of these processings will be described in the description of the operation of the present embodiment.

<Regarding the electrical model adopted in this embodiment> A. Four-Element Lumped Constant Model In this embodiment, a four-element lumped constant model is adopted as the electrical model of the arterial system. This four-element lumped constant model is
Among the factors that determine the behavior of the human circulatory system, blood inertia in the central part of the arterial system, vascular resistance (viscous resistance) due to blood viscosity in the central part, vascular compliance (viscoelasticity) in the central part, and peripheral It focuses on four parameters of blood vessel resistance (viscous resistance) in the part and models them as an electric circuit. FIG. 3 shows a circuit diagram of the four-element lumped constant model. Hereinafter, the correspondence relationship between each element constituting the four-element lumped constant model and each of the above parameters will be shown. Inductance L: Inertia of blood in the central part of arterial system [dy
n · s ² / cm ⁵ ] Capacitance C: Compliance (viscoelasticity) of blood vessels in the central part of the arterial system [cm ⁵ / dyn] Note that compliance is a quantity that represents the softness of blood vessels, and That is. Electric resistance R _c : vascular resistance due to blood viscosity in the central part of the arterial system [dyn · s / cm ⁵ ] Electric resistance R _p : vascular resistance due to blood viscosity in the peripheral part of the arterial system [dyn · s / cm ⁵ ] The currents i, i _P , i _c flowing through each part in this electric circuit
Corresponds to the blood flow [cm ³ / s] flowing through each corresponding part. The input voltage e applied to this electric circuit corresponds to the pressure [dyn / cm ² ] at the origin of the aorta. The terminal voltage v _P of the capacitance C is the pressure [dyn / cm
² ].

B. Four-element lumped parameter model and approximate expression of its response characteristic Next, a theoretical explanation will be given of the behavior of the four-element lumped parameter model shown in FIG. First, in the four-element lumped constant model shown in FIG. 3, the following differential equation holds. e = R _c i + L (di / dt) + v _p (1) where the current i is i = i _c + i _p = C (dv _p / dt) + (v _p / R _p ). .. (2) can be represented, so the above formula (1) is represented by the following formula (3)
Can be expressed as e = LC (d ² v _p / dt ² ) + {R _c C + (L / R _p )} (dv _p / dt) + (1+ (R _c / R _p )) v _p ··· (3) As is well known, a general solution of a quadratic constant coefficient ordinary differential equation represented by the above equation (3) is a special solution (steady solution) satisfying the above equation (3) and a transient solution satisfying the following differential equation. Given by the sum of the solution. 0 = LC (d ² v _p / dt ² ) + {R _c C + (L / R _p )} (dv _p / dt) + (1+ (R _c / R _p )) v _p (4)

Here, the solution of the differential equation (4) is obtained as follows. First, a damped oscillation waveform represented by the following equation (5) is assumed as the solution of the differential equation (4). v _p = A exp (st) ··· (5) When this equation (5) is substituted into the equation (4), the equation (4) is expressed as follows. {LCs ² + (R _c C + (L / R _p )) s + (1+ (R _c / R _p ))} v _p = 0 ... (6) Then, solving the above equation (6) for s , S = {− (R _c C + (L / R _p )) ± √ ((R _c C + (L / R _p )) ² −4LC (1+ (R _c / R _p )))} / 2LC ...・ It becomes (7). In the formula (7), if (R _c C + (L / R _p )) ² <4LC (1+ (R _c / R _p )) ... (8), then in the square root √ of the second term Becomes negative, and in this case, s is expressed as follows. s = {− (R _c C + (L / R _p )) ± j√ (4LC (1+ (R _c / R _p )) − (R _c C + (L / R _p )) ² )} / 2LC = −α ± jω ··· (9) α = (R _c C + (L / R _p )) / 2LC = (L + R _p R _c C) / 2LCR _p ··· (10) ω = {√ (4LC (1+ _{(R c / R p))} - (R c C + (L / R p)) 2)} / 2LC ···· (11) _{where, A 1 = LC ···· (12} ) A 2 = ( L + R _C R _P C) / R _p ··· (13) A ₃ = (R _C + R _P ) / R _p ··· (14), the above formulas (10) and (11) are Can be expressed as α = A ₂ / 2A ₁ (15) ω = √ {(A ₃ / A ₁ ) −α ² } (16) In this way, the value of s is determined, and the differential equation (4)
A solution that satisfies is obtained. Based on the above findings, in the present embodiment, the above formula (5) is used as a formula for approximating the damping vibration component included in the response waveform of the four-element lumped constant model.

Next, the pressure waveform at the aortic origin is modeled. Generally, the pressure waveform at the aortic origin is as shown in FIG. Therefore, this pressure waveform will be approximated by the triangular wave shown in FIG. In FIG. 6, assuming that the amplitude and time of the approximate waveform are E _o , E _m , t _P , and t _P1 , the aortic pressure e at an arbitrary time t is expressed by the following equation. E _o is the minimum blood pressure (diastolic blood pressure), E _o + E _m is the maximum blood pressure (systolic blood pressure), t _P is the time of one beat, and t _P1 is the minimum blood pressure value from the rise of aortic pressure. It's time to go. Section of 0 ≦ t <t _P1 : e = E _o + E _m (1- (t / t _P1 )) (17) Section of t _P1 ≦ t <t _P : e = E _o (18) Then, in the present embodiment, the response waveform v _p (corresponding to the radial artery wave) when the electric signal e represented by the equations (17) and (18) is input to the equivalent circuit of FIG. It is approximated as follows. Section of 0 ≦ t <t _P1 : v _P = E _min + B (1-t / t _b ) + D _m1 exp (−αt) sin (ωt + θ ₁ ) ... (19) t _P1 ≦ t <t _P Interval: v _P = E _min + D _m2 · exp {−α (t−t _P1 )} · sin {ω (t−t _P1 ) + θ ₂ } ... (20) Third part on the right side in the above equation (19) And the above equation (2
The second term on the right side in (0) is the damping vibration component (corresponding to the above equation (5)) already described, and α and ω in these terms are given by the above equations (15) and (16).

C. Parameters and radius of four-element concentrated model
Relationship with Bone Arterial Waveform Hereinafter, of the constants in the above equations (19) and (20), those other than the already determined α and ω will be examined. First, by substituting the equations (17) and (19) into the differential equation (3), the following equation (21) is obtained. E ₀ + E _m (1- (t / t _p1 )) = (1+ (R _c / R _p )) (E _min + B) − (B / t _b ) (R _c C + (L / R _p )) t + {LC (α ² −ω ² ) D _m1 −αD _m1 (R _c C + (L / R _p )) + D _m1 (1+ (R _c / R _p ))} exp (−αt) sin (ωt + θ ₁ ) + { ωD _m1 (R _c C + (L / R _p ))-2LCα ωD _m1 } exp (-αt) cos (ωt + θ ₁ ) ... (21) The following conditions are necessary to satisfy this equation (21). Is. _{E 0 + E m = (1+} (R c / R p)) (E min + B) = E 0 + A 3 B- (B / t b) A 2 ···· (22) E m / t p1 = (B _{/ t b) (1+ (R} c / R p)) = B / (t b A 3) ···· (23) LC (α 2 -ω 2) -α (R c C + (L / R p) ) + (1 + R _c / R _p ) = 0 ... (24) R _c C + (L / R _p ) = 2LCα ... (25) In addition, the equations (24) and (25) among the above equations are Although constraining α and ω, α and ω already obtained by the equations (15) and (16) naturally satisfy these equations. On the other hand, by substituting the equations (18) and (20) into the differential equation (3), the following equation (26) is obtained. E ₀ = (1+ (R _c / R _p )) E min + {LC (α ² −ω ² ) D _m2 −α (R _c C + (L / R _p )) D _m2 + (1+ (R _c / R
_p )) D _m2 } exp (-α (t-t _p1 )) sin (ω (t-t _p1 ) + θ ₂ ) + {ω (R _c C + (L / R _p )) D _m2 -2LCαωD _m2 } exp (−α (t−t _p1 )) cos (ω (t−t _p1 ) + θ ₂ ) ... (26) In order for this equation (26) to hold, the above equation (23),
In addition to the condition (24) being satisfied, the following formula (27) must be satisfied. E ₀ = (1+ (R _c / R _p )) E _min = A ₃ E _min ... (27)

Conditional expressions (22) to (25) for realizing the differential equation (3) obtained as described above,
Based on (27), each constant in equations (19) and (20) is calculated. First, E _min is obtained from the above equation (27), E _min = E _o / A ₃ ... (28) Next, from equation (23), B is B = (t _{b Em} ) / (t _P1 A ₃ ) ・ ・ ・ ・ (29). Now solved for by substituting the above equation (29) into the equation _{(22) t b, t b} = become _{(t P1 A 3 + A 2} ) / A 3 ···· (30).

The remaining constants D _1m , D _2m , θ ₁ and θ ₂ are values such that the radial artery waveform v _p can maintain continuity at t = 0, t _p1 , t _p , that is, Condition a
A value that satisfies ~ d is selected. a. V _p (t _p1 ) in equation (19) and v _{p in} equation (20)
match _p (t _p1 ) b. V _p of v _p (t _p) and formula (19) in equation (20) (0)
Must match c. The differential coefficients at t = t _p1 in the equations (19) and (20) match, d. Derivative of t = 0 in equation (19) and equation (20)
I.e. t = t _p in the differential coefficient matching, D _{1 m} and theta _{1 is, D 1m = √ {(D} 11 2 + D 12 2)} / ω ···· (31) θ 1 = D 11 / The value D ₁₂ ... (32) is selected. However, in each of the above formulas, D ₁₁ = (v _O1 −B) ω ··· (33) D ₁₂ = (v _O1 −B) α + (B / t ₀ ) + (i _O1 / C) (34) and v _O1 and i _O1 are initial values of v _P and i _P at t = 0. Further, D _2m and θ ₂ are selected such that D _2m = √ (D ₂₁ ² + D ₂₂ ² ) / ω (35) θ ₂ = D ₂₁ / D ₂₂ (36) . However, in the above equations, D ₂₁ = v _O2 · ω ··· (37) D ₂₂ = v _O2 · α + (i _O2 / C) ··· (38), and v _O2 and l _O2 are t = Initial values of v _P and i _P at t _P1 . In this way, the constants of equations (19) and (20) were obtained.

Now, the blood vessel resistance R _C at the central portion is calculated by back-calculating from the angular frequency ω of the equation (16), R _C = {L-2R _P √ (LC (1-ω ² LC))} / CR It becomes _r・ ・ ・ (39). Here, the conditions R _C is a real number a and positive is ^{_{4R r 2 C / {l +}} (2ωR P C) 2} ≦ L ≦ 1 / ω 2 C ···· (40). Generally, the order of R _P is about 10 ³ (dyn · s / cm ⁵ ), C is about 10 ⁻⁴ (cm ⁵ / dyn), and ω is the angular frequency of the vibration component superimposed on the pulse wave. Because there is 10
(Rad / s) or higher. Therefore, the formula (4
The lower limit of 0) can be regarded as approximately 1 / ω ² C. Therefore, when L is approximately set to L = 1 / (ω ² C) ··· (41) for simplification, R _C is R _C = L / (CR _P ) ··· ( 42). Further, from the relationship between the equations (41) and (42), the damping constant α of the equation (15) becomes α = 1 / (CR _P ) ... (43). Using the relations of equations (41) to (43), if one of α and ω and four constants, for example, the inertia L of blood, is used to represent the remaining parameters, then R _C = αL ... (44) R _P = ω ² L / α (45) C = 1 / (ω ² L) (46) From the above equations (44) to (46), it is clear that the model parameters are determined by obtaining α, ω and L.

Here, α and ω can be obtained from the actually measured waveform of the radial artery wave. On the other hand, L can be calculated based on the stroke volume SV. The procedure for calculating L based on the stroke volume SV will be described below. First, the average value E ₀₁ of the pressure wave at the aortic origin is given by the following equation (47). E ₀₁ = {E ₀ t _p + (t _p1 E _m / 2)} / t _p (47) On the other hand, between Rc, Rp, α, ω and L, the following formula (48)
Is established. R _c + R _p = αL + (ω ² L / α) = (α ² + ω ² ) L / α (48) Then, the average current flowing through the four-element lumped constant model, that is, E ₀₁ is R _c The value divided by + R _p corresponds to the average value (SV / t _p ) of the blood flow flowing through the artery due to the pulsation, and therefore the following equation (49) is established. SV / t _p = 1333.22 (1 / t _p ) {E ₀ t _p + (t _p1 E _m / 2)} (α ² + ω ² ) / (αL) (49) The above equation (49) 1333.32 in) is a proportional constant for converting the unit of pressure value from mmHg to dyn / cm ² .
By solving the equation (49) thus obtained for L, the equation (5
0) is obtained as follows. L = 1333.22 {E ₀ t _p + (t _p1 E _m / 2)} (α ² + ω ² ) / (α · SV) (50) The above equation (49) is obtained by measuring the blood flow. The value corresponding to the average current (1 / t _p ) {E ₀ t _p + (t _p1 E _m / 2)} in () may be obtained, and the inductance L may be calculated based on this result. As a device for measuring blood flow, an impedance method, a Doppler method, and the like are known. In addition, the blood flow measuring device by the Doppler method includes a device using ultrasonic waves and a device using laser.

D. Development of Four-Element Concentrated Model Next, the model shown in FIG. 17 is obtained by developing the model shown in FIG. 3 and considering the respective pressure changes in dimension, function, and scale. In the figure, the pressures at the aortic root, shaku, seki, and kaku are represented by voltages e ₀ , e ₁ , e ₂ and e ₃ , respectively, and between each voltage detecting end, an inductance L ₁ indicating the inertia of blood is obtained. ˜L ₃ , capacitances C _{1 to} C ₃ indicating compliance of each part of the blood vessel, and electric resistances R _{c1 to} R _c3 indicating resistance of each part of the blood vessel are connected.

The electrical resistance R _p in FIG. 3 indicates the vascular resistance further peripheral than the peripheral portion of the arterial system to be measured. Therefore, in the model shown in FIG.
The combined impedance of the circuit located at the stage subsequent to each voltage detection end corresponds to the electric resistance R _p in FIG. For example, in FIG. 17, assuming that the combined impedance of the portion on the right side of the alternate long and short dash line AA ′ is approximated as an electric resistance R _p , the model of FIG. 17 becomes the same as the model of FIG.

Therefore, the model in FIG.
Each circuit constant can be obtained by the same method as the model shown in FIG. That is, first, the dashed line A
Assuming that the combined impedance of the portion on the right side of −A ′ is approximated as an electric resistance R _p , each parameter R _c1 , L ₁ and C is calculated based on the waveforms of e ₀ and e ₁ by the above-described method.
₁ is required. Next, the parameters R _c2, L ₂ and C ₂ is determined based on the waveform of e ₁ and e _2, the parameters on the basis of the waveform of e ₂ and _{e 3 R c3, L 3,} R p3 and C ₃ Is required.

By the way, in the above description, the voltage e
The pressure waveform of each part corresponding to _{1 to} e ₃ can be detected as it is. However, in reality, the pressure waveform generated in the blood vessel of the subject is the strain gauges 52 to 54 (see FIG. 15).
Prior to being detected by, it is transformed as it propagates through the subject's muscles, fat, skin, etc.

Therefore, if more precise measurement is performed, it is necessary to consider the deformation of the pressure waveform. In this case, FIG.
It may be preferable to provide the pressure wave deformation circuits 70 to 72 as shown in FIG. In the circuit 70, 73 is a voltage follower circuit, 74 and 75 are electric resistances, and 76 is a capacitor. Here, the electric resistances 74 and 75 simulate the pressure loss from the portion corresponding to the “scale” of the subject's artery to the strain gauge 54, and the electric resistance 75 and the capacitor 76 are frequency characteristics, that is, a high frequency portion. Simulates the decay at. Further, the voltage follower circuit 73 is provided before the electric resistance 74 because it is considered that the state of muscles, fat, skin, etc. has little influence on the artery itself.

In this model, the voltage e ₁ is deformed by the pressure wave deformation circuit 70 and detected as the voltage e ₁ ′. Therefore, in order to correctly obtain the waveform of the voltage e ₁ , it is necessary to obtain the constants of the respective elements in the pressure wave deformation circuit 70. This can be easily obtained by applying sound waves having various frequencies and waveforms to the arm of the subject and detecting loss or deformation of the sound waves. That is, since the circuit configuration of the pressure wave modification circuit 70 is similar to that of the model of FIG. 3, each constant can be obtained by a similar method. It should be noted that each constant in the pressure wave deformation circuit 70 is not fixed and varies depending on the pressing force of the finger when the diagnostician performs pulse diagnosis, and therefore when applying a sound wave to the arm of the subject, It is preferable to apply various pressing forces and record the pressing force and each constant in association with each other.

The relationship between the radial arterial wave and the stroke volume and the value of each element of the four-element lumped constant model has been described above. The microcomputer 4 in this embodiment calculates the value of each element of the four-element lumped constant model based on the relationship described above.

<Operation of Embodiment> FIGS. 6 to 10 are flowcharts showing the operation of the pulse wave analyzing apparatus. Also, FIG.
1 is a waveform diagram showing a radial artery waveform obtained by the averaging process, and FIG. 9 is a radial artery waveform W2 obtained by the parameter calculation process and a radial artery waveform W1 obtained by the averaging process.
It is a waveform diagram which contrasted with. The operation of this embodiment will be described below with reference to these drawings.

A. Normal measurement process Pulse wave reading process When assessing hemodynamic parameters, the diagnostician
As shown in, the cuff band S2 is attached to the subject, the pulse wave sensor S1 is attached to the hand of the diagnostician, the switch 66a (see FIG. 16) is pressed, and the measurement instruction is input from the keyboard 5.
In response to this command, the microcomputer 4 first sends a measurement instruction to the pulse wave detection device 1. As a result, the pulse wave detection device 1 detects the radial artery wave via the strain gauges 52 to 54, and a time-series digital signal representing the radial artery wave is output from the A / D converter 3 for a fixed time (about It is taken into the microcomputer 4 for 1 minute).
In this way, the microcomputer 4 receives the time-series digital signals of the radial artery waveforms for a plurality of beats.

Averaging process Next, the microcomputer 4 superimposes the radial artery waveforms corresponding to a plurality of beats thus captured for each beat to obtain an average waveform per beat in one minute, and the average The waveform is stored in the built-in memory as a representative waveform of the radial artery waveform (above, step S1). At the same time, the pressing force detected via the subtractor 67 (see FIG. 16) is also averaged. FIG. 11 illustrates a representative waveform W1 of the radial artery waveform stored in the memory in this way.

Stroke Volume Data Acquisition Processing Upon completion of the averaging processing, the microcomputer 4
Sends a measurement instruction to the stroke volume measuring device 2. As a result, 1
The stroke volume of the subject is measured by the stroke volume measuring device 2, and the stroke volume data indicating the result is loaded into the microcomputer 4 (step S2).

Parameter Calculation Processing Next, the processing of the microcomputer 4 proceeds to step S3, and the parameter calculation processing routine whose flow is shown in FIGS. 7 and 8 is executed. Further, along with the execution of this routine, an α, ω calculation routine whose flow is shown in FIG. 9 is executed for each waveform of each of the dimensions, functions, and scales (steps S109, S).
117), along with the execution of this α, ω calculation routine,
The ω calculation routine whose flow is shown in 0 is executed (step S203). In order to simplify the description, in these routines, the voltages e ₁ to
The pressure waveform corresponding to e ₃ was obtained directly from the strain gauges 52 to 54. The processing contents of these routines will be described below.

First, the microcomputer 4 takes the time t ₁ and the blood pressure value y ₁ corresponding to the first point P1 at which the blood pressure becomes maximum, and the blood pressure value y ₁ after the first point, for the radial artery waveform for one beat stored in the memory. , Blood pressure drops once
The time t ₂ corresponding to the point and the blood pressure value y _2, and the time t ₃ corresponding to the third point P3 which is the second peak point.
And the blood pressure value y ₃ are calculated. Further, regarding the radial artery waveform stored in the memory, the time t _P of one beat and the minimum blood pressure value Emin
(Corresponding to the first item of equations (3) and (4)) is calculated (step S101). Through the above processing, the data exemplified below can be obtained as each data necessary for the parameter calculation processing.

First point: t ₁ = 0.104 (s), y ₁ = 123.
4 (mmHg) Second point: t ₂ = 0.264 (s), y ₂ = 93.8
(MmHg) Third point: t ₃ = 0.38. (S), y ₃ = 103.
1 (mmHg) 1 beat time: t _P = 0.784 (s) Minimum blood pressure: E _min = 87.7 (mmHg) Stroke volume data: SV = 90 (cc / beat) Second point In the case of a gentle pulse wave in which it is difficult to distinguish P2 from the third point P3, the blood pressure value at that point is determined by setting the times of the second and third points to t ₂ = 2t ₁ and t ₃ = 3t _1. To do. Then, in order to simplify the calculation, FIG.
The blood pressure value y ₀ at the point A shown in 3 is used to perform normalization processing of y ₁ to y ₃ (steps S102 and S103), and the value of B is initialized to (y ₀ /2)-0.1 (step). S10
4).

Then, the optimum values of B, t _b , α and ω are obtained by the following procedure. a. First, B a is varied in the range of y ₀ / 2~y ₀ changing the t _b in the range of t _p / 2~t _p simultaneously (+0.1 intervals), each B and t _b for v _p (t ₁ ) -y ₁ , vp
(T ₂ ) −y ₂ , v _p (t ₃ ) −y ₃ is determined to be minimum α and ω. b. Among B, t _b , α and ω obtained in a, v
B, t _b , α, and ω that minimize _p (t ₁ ) -y ₁ , v _p (t ₂ ) -y ₂ , v _p (t ₃ ) -y ₃ are obtained. c. B obtained in b, based on the t _{b, B} ± 0.
The above a and b are executed again within the range of 05, t _b ± 0.05.

D. In the processing of the above ac, α is 3 to 10
The range of is changed by 0.1 intervals and the optimum ω for each α
To calculate. ω is dv _p (t ₂ ) / dt for each α
The point where = 0 was obtained using the bisection method (see FIG. 10).
Note that the initial value v _o1 of the equation (33) is set to zero _when calculating the value of v _p in each of the above processes. By such processing, each data is determined as exemplified below. α = 4.2 (s ⁻¹ ), ω = 24.325 (rad / s) B = 27.2 (mmHg), t _b = 0.602 (s)

F. Then, t _P1 , E _m , and E _o are given by equation (28).
To (30) and (44) to (46) (steps S123 and S124). The results illustrated below are obtained. t _P1 = 0.588 (s) E _m = 46.5 (mmHg) E _o = 90.3 (mmHg)

G. Then, using Expression (50), the value of L is calculated from the stroke volume (Step S125), and the remaining parameter values are obtained from Expressions (44) to (46) (Step S126). As a result, the parameters exemplified below are obtained. L = 7.021 (dyn · s ² / cm ⁵ ) C = 2.407 × 10 ⁻⁴ (cm ⁵ / dyn) R _C = 29.5 (dyn · s / cm ⁵ ) R _P = 958.2 ( dyn · s / cm ⁵ ) Moreover, direct current (average) total peripheral vascular resistance TPR is calculated as follows. _{TPR = R C + R P =} 1018.7 becomes ^{(dyn · s / cm 5)} .

Output Processing Upon completion of the parameter calculation processing described above, the microcomputer 4 outputs L, C, _RC and _RP from the output device (step S4). That is, the parameters L _{1 to} L ₃ , C _{1 to} C ₃ and R _{C1 to} R shown in FIG.
_C3 and R _P3 are obtained.

For confirmation, the equation (4
0) is calculated to be 6.969 ≦ L ≦ 7.036, and it can be said that the approximation of the equation (41) is appropriate. Further, as shown in FIG. 12, it can be said that the radial artery waveform calculated using the calculated parameters and the actually measured waveform (average waveform for 1 minute) match very well.

B. Continuous measurement The device according to the present embodiment is equipped with a timer (not shown), and by using this timer, the hemodynamic parameters can be continuously measured for a long time. When performing this continuous measurement, the diagnostician inputs a continuous measurement instruction from the keyboard 5. As a result, after step S4 (output process) in FIG. 6 is completed, the timer is set, and after the timer measures a certain time, execution is started again from step S1 and the circulatory dynamics parameter is measured (step S3) is recorded on recording paper or a storage medium (step S4). In this way, continuous measurement of hemodynamic parameters is performed at regular time intervals.

Furthermore, the diagnostician may appropriately change the pressing force of the finger each time the timer measures a certain time. That is, in a general pulse diagnosis, the diagnostician performs various diagnoses while appropriately changing the pressing force of the finger and collects various information, so that even if such a pulse diagnosis is performed while operating the apparatus of the present embodiment. Good. This makes it possible to collect data according to various pressing forces.

<Modifications> The present invention can be implemented in the modes listed below in addition to the modes described above. (1) Without measuring the stroke volume SV, L is assumed to be a predetermined value, and the hemodynamic parameter is obtained only from the radial artery waveform. In order to compensate for the decrease in calculation accuracy, a monitor is provided to display the radial artery waveform obtained by the calculation and the radial artery waveform obtained by the measurement as shown in FIG. 12, and the diagnostician sets the value of L. You may get it. With this configuration, the diagnostician can set L to an optimum value by trial and error so that the measured radial artery waveform matches the calculated radial artery waveform.

(2) A trapezoidal wave as shown in FIG. 14 is used instead of a triangular wave as a model of the pressure waveform at the origin of the aorta. In this case, since it is closer to the actual pressure waveform than the triangular wave, the circulatory dynamics parameter can be obtained more accurately.

(3) In the above embodiment, the circulatory dynamic parameters were obtained by calculation using mathematical formulas. However, each response waveform of the model when each circulatory dynamic parameter was changed within a predetermined range was obtained by a circuit simulator or the like. It is also possible to perform simulation and select and output a hemodynamic parameter that best matches the actually measured radial artery waveform. In this case, as the electrical model of the arterial system and the model of the pressure waveform at the origin of the aorta, more complicated ones can be used, and the measurement accuracy is further improved.

(4) The measurement points of the radial artery wave and the stroke volume are not limited to those shown in FIG. For example, by attaching a blood pressure sensor to the rubber gloves 51, both the radial artery waveform and the stroke volume may be measured at the wrist. In this case, the subject does not have to wrap his arms, so the burden on the subject is reduced. Similarly, the stroke volume measuring device may be provided on the arm, hand, or finger opposite to the arm on which the pulse diagnosis is performed.

(5) In the above embodiment, for simplification of the description, the pressure waveforms corresponding to the voltages e _{1 to} e ₃ in the model of FIG. 17 are obtained directly from the strain gauges 52 to 54. However, it goes without saying that the diagnosis may be performed using a model including the pressure wave deformation circuits 70 to 72.

[0057]

As described above, in the configuration according to claim 1, when the pulse wave sensor detects a plurality of radial artery waves of the subject, the evaluation means calculates the value of each element of the electric circuit. Therefore, it is possible to evaluate hemodynamic parameters non-invasively with an inexpensive configuration. Further, in the configuration according to claim 2, since the detection signal corresponding to the pulse wave is obtained from the detection means and the pulse wave is propagated to the fingertip of the examiner through the thin film member, measurement by the sensor It is possible to simultaneously perform the diagnosis based on the sense of touch of the diagnostician. Further, in the configuration according to claim 3, since the detection signal corresponding to the pulse wave is obtained from the AC component detecting means, and the signal corresponding to the pressing force of the finger is obtained from the DC component detecting means. It is possible to detect the finger pressing force along with the wave.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a pulse wave analysis device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a measurement mode using a pulse wave detection device 1 and a stroke volume measuring device 2 in the same Example.

FIG. 3 is a circuit diagram showing a basic four-element lumped constant model used as a model of the human arterial system in the same Example.

FIG. 4 is a diagram showing a blood pressure waveform at the aortic root of a human body.

FIG. 5 is a waveform diagram showing a waveform obtained by modeling the blood pressure waveform of the aortic origin.

FIG. 6 is a flowchart showing the operation of the embodiment.

FIG. 7 is a flowchart showing the operation of the embodiment.

FIG. 8 is a flowchart showing the operation of the embodiment.

FIG. 9 is a flowchart showing the operation of the embodiment.

FIG. 10 is a flowchart showing the operation of the embodiment.

FIG. 11 is a waveform diagram illustrating a radial artery waveform obtained by the averaging process of the example.

FIG. 12 is a waveform diagram in which the radial artery waveform obtained by the arithmetic processing of the embodiment and the radial artery waveform obtained by the averaging processing are displayed in an overlapping manner.

FIG. 13 is a diagram illustrating the radial artery waveform obtained by the averaging process of the same example and explaining the contents of the process applied to the waveform.

FIG. 14 is a waveform diagram showing another model of the blood pressure waveform at the aortic root.

FIG. 15 is a perspective view of a pulse wave sensor S1.

FIG. 16 is a block diagram of a pulse wave detecting device 1 of the same embodiment.

FIG. 17 is a circuit diagram showing a four-element lumped constant model used as a model of the human arterial system in the example.

[Explanation of symbols]

 1 pulse wave detection device (evaluation means) 4 microcomputer (evaluation means) 51 rubber gloves (pulse wave sensor, thin film member) 52 strain gauge (pulse wave sensor, pressure detection means) 65 averaging circuit (DC component detection means) 63 DC cutoff circuit (AC component detection means) 66 Level storage circuit (storage means) 67 Subtractor (subtraction means)

[Procedure amendment]

[Submission date] November 26, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0024

[Correction method] Change

[Correction content]

Next, the pressure waveform at the aortic origin is modeled. Generally, the pressure waveform at the aortic origin is as shown in FIG. Therefore, to be approximated by the triangular wave indicating this pressure waveform in FIG. In FIG. 5 , assuming that the amplitude and time of the approximate waveform are E _o , E _m , t _P , and t _P1 , the aortic pressure e at an arbitrary time t is expressed by the following equation. E _o is the minimum blood pressure (diastolic blood pressure), E _o + E _m is the maximum blood pressure (systolic blood pressure), t _P is the time of one beat, and t _P1 is the minimum blood pressure value from the rise of aortic pressure. It's time to go. Section of 0 ≦ t <t _P1 : e = E _o + E _m (1- (t / t _P1 )) (17) Section of t _P1 ≦ t <t _P : e = E _o (18) Then, in this embodiment, the response waveform v _p (corresponding to the radial artery wave) when the electric signal e represented by the above equations (17) and (18) is input to the equivalent circuit of FIG. It is approximated as follows. Section of 0 ≦ t <t _P1 : v _P = E _min + B (1-t / t _b ) + D _m1 exp (−αt) sin (ωt + θ ₁ ) ... (19) t _P1 ≦ t <t _P Interval: v _P = E _min + D _m2 · exp {−α (t−t _P1 )} · sin {ω (t−t _P1 ) + θ ₂ } ... (20) Third part on the right side in the above equation (19) And the above equation (2
The second term on the right-hand side in (0) is the damping vibration part (corresponding to the above equation (5)) already described, and α and ω in these terms are given by the above equations (15) and (16).

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0027

[Correction method] Change

[Correction content]

The remaining constants D _1m , D _2m , θ ₁ and θ ₂ are values such that the radial artery waveform v _p can maintain continuity at t = 0, t _p1 , t _p , that is, Condition a
A value that satisfies ~ d is selected. a. V _p (t _p1 ) in equation (19) and v _{p in} equation (20)
match _p (t _p1 ) b. V _p of v _p (t _p) and formula (19) in equation (20) (0)
Must match c. The differential coefficients at t = t _p1 in the equations (19) and (20) match, d. Derivative of t = 0 in equation (19) and equation (20)
I.e. the derivative of the t = t _p are matched, D _{1 m} and theta _{1 is, D 1m = √ {(D} 11 2 + D 12 2)} / ω ···· (31) θ 1 = tan -1 The value of (D ₁₁ / D ₁₂ ) ... (32) is selected. However, in the above _{formulas, D 11 = (v 01 -B} -E min) ω ···· (33) D 12 = (v 01 -B-E min) α + (B / t b) + (i 01 / C) ... (34) , and v ₀₁ and i ₀₁ are initial values of v _P and i _c at t = 0. Further, D _2m and θ ₂ are D _2m = √ (D ₂₁ ² + D ₂₂ ² ) / ω ··· (35) θ ₂ = tan ⁻¹ (D ₂₁ / D ₂₂ ) ·· (36) Is selected. However, in the above equations, D ₂₁ = (v ₀₂ −E _min ) ω ··· (37) D ₂₂ = (v ₀₂ −E _min ) α + (i ₀₂ / C) ··· (38) , V ₀₂ and i ₀₂ are initial values of v _P and i _c at t = t _P1 . In this way, the constants of equations (19) and (20) were obtained.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0028

[Correction method] Change

[Correction content]

[0028] Now, the vascular resistance R _c at the central portion by backward from the angular frequency omega of the formula _{(16), R c = {} L-2R P √ (LC (1-ω 2 LC))} / CR It becomes _P ... (39). Here, the condition for R _c is a real number a and positive is ^{_{4R P 2 C / {1+ (}} 2ωR P C) 2} ≦ L ≦ 1 / ω 2 C ···· (40). Generally, the order of R _P is about 10 ³ (dyn · s / cm ⁵ ), C is about 10 ⁻⁴ (cm ⁵ / dyn), and ω is the angular frequency of the vibration component superimposed on the pulse wave. Because there is 10
(Rad / s) or higher. Therefore, the formula (4
The lower limit of 0) can be regarded as approximately 1 / ω ² C. Therefore, when L is approximately set to L = 1 / (ω ² C) ··· (41) for simplification, R _c is R _c = L / (CR _P ) ··· (( 42). Further, from the relationship between the equations (41) and (42), the damping constant α of the equation (15) becomes α = 1 / (CR _P ) ... (43). Using the relationships of equations (41) to (43), if one of α and ω and four constants, for example, the inertia L of blood, is used to represent the remaining parameters, R _c = αL ... (44) R _P = ω ² L / α (45) C = 1 / (ω ² L) (46) From the above equations (44) to (46), it is clear that the model parameters are determined by obtaining α, ω and L.

[Procedure amendment 4]

[Document name to be amended] Statement

[Name of item to be corrected] 0037

[Correction method] Change

[Correction content]

<Operation of Embodiment> FIGS. 6 to 10 are flowcharts showing the operation of the pulse wave analyzing apparatus. Also, FIG.
1 is a waveform diagram showing the radial artery waveform obtained by the averaging process, and FIG. 12 is the radial artery waveform W2 obtained by the parameter calculating process and the radial artery waveform W obtained by the averaging process.
It is a waveform diagram which compared with 1. The operation of this embodiment will be described below with reference to these drawings.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0043

[Correction method] Change

[Correction content]

First point: t ₁ = 0.104 (s), y ₁ = 123.
4 (mmHg) Second point: t ₂ = 0.264 (s), y ₂ = 93.8
(MmHg) Third point: t ₃ = 0.38. (S), y ₃ = 103.
1 (mmHg) 1 beat time: t _P = 0.784 (s) Minimum blood pressure: E _min = 87.7 (mmHg) Stroke volume data: SV = 103.19 (cc / beat) In the case of a gentle pulse wave in which it is difficult to distinguish the second point P2 and the third point P3, the time between the second and third points is set to t ₂ = 2t ₁ , t ₃ = 3t _{1 and} the blood pressure value at that point is set. To decide. Then, in order to simplify the calculation, FIG.
With a blood pressure value y _o at point A shown in 3 performs normalization processing of y ₁ ~y ₃ (step S102, S103), initializes the value of B (y _o /2)-0.1 ( Step S10
4).

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0046

[Correction method] Change

[Correction content]

F. Then, t _P1 , E _m , and E _o are given by equation (28).
To (30) and (44) to (46) (steps S123 and S124). The results illustrated below are obtained. t _P1 = 0.588 (s) E _m = 27.4 (mmHg) E _o = 90.3 (mmHg)

[Procedure Amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0049

[Correction method] Change

[Correction content]

For confirmation, the equation (4
0) is calculated to be 6.969 ≦ L ≦ 7.021 , and it can be said that the approximation of the equation (41) is appropriate. Further, as shown in FIG. 12, it can be said that the radial artery waveform calculated using the calculated parameters and the actually measured waveform (average waveform for 1 minute) match very well.

Claims (3)

[Claims] 1. A plurality of pulse wave sensors for detecting a radial artery wave of a subject, and means for calculating values of respective elements of an electric circuit imitating a system from a central part to a peripheral part of an arterial system of a human body. , The value of each element of the electric circuit is calculated so that the output signal waveform obtained from the electric circuit becomes a waveform corresponding to the radial artery wave when an electric signal corresponding to the pressure wave of the aortic origin is given. And a pulse wave analysis device. 2. A pulse wave sensor, comprising: a thin film member attached to a finger of an examiner; and thin pressure detecting means fixed to the thin film member. 3. A pulse wave sensor comprising a thin film member attached to the examiner's finger and a thin pressure detecting means fixed to the thin film member, and a direct current component is detected from a detection signal of the pulse wave sensor. DC component detection means, AC component detection means for detecting an AC component from the detection signal of the pulse wave sensor, storage means for appropriately storing the detection result in the DC component detection means, and data stored in the storage means A pulse wave detecting apparatus comprising: a subtracting unit that outputs a difference from the detection result of the DC component detecting unit.