JPH11178802A - Device and method for measuring biological condition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately estimate central blood pressure by use of simple constitution and calculate a more accurate myocardial load index WP which corresponds to the actual myocardial load. SOLUTION: A microcomputer 4 can accurately estimate central blood pressure while simplifying its constitution, since it calculates an estimate of aortal origin blood pressure on the basis of a circulation kinetic parameter obtained by analyzing a pulse waveform output from a pulse wave detection device 1. The microcomputer 4 detects the pulse rate of a living body and calculates a myocardial load index on the basis of the estimate of the aortal origin blood pressure and the detected pulse rate, and can therefore calculate an optimum myocardial load index under a wider range conditions than it can when calculating the aortal load index by use of peripheral blood pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biological condition measuring device and a biological condition measuring method suitable for measuring the condition of a human body as a living body, and more particularly to a biological condition measuring device and a biological condition measuring device suitable for calculating a myocardial load index. The present invention relates to a biological condition measuring method.

[0002]

2. Description of the Related Art When diagnosing the condition of the circulatory system of the human body, blood pressure, heart rate and the like are most commonly used. However, in order to make a more detailed diagnosis, it is necessary to measure so-called circulatory parameters such as viscous resistance and compliance of blood vessels.

When these circulatory dynamic parameters are modeled and represented, a four-element lumped parameter model is used as a model for describing the behavior of the arterial system. On the other hand, in order to measure the circulatory parameters, it is necessary to measure the pressure waveform and blood flow at the aortic root and the notch. That is, a method of directly measuring by inserting a catheter into an artery or a method of indirectly measuring by ultrasonic waves or the like is adopted.

[0004] The above-described method of directly measuring a patient by inserting a catheter into a pulse involves invasive measurement, which places a heavy burden on the subject, and has a problem that the device becomes large-scale. On the other hand, in the method of indirect measurement using ultrasonic waves or the like, the blood flow in the blood vessel can be observed noninvasively, and the burden on the subject can be reduced. However, there is also a problem that the apparatus for the above is also large-scale.

Therefore, the present inventor has found a method of approximately calculating the parameters of the four-element lumped parameter model by measuring the pulse waveform of the radial artery and the stroke volume.
By using this method, a pulse wave analyzer capable of non-invasively and easily evaluating circulatory dynamic parameters has been proposed (JP-A-6-205747,
Title of invention: pulse wave analyzer).

By the way, in the method of approximately calculating the parameters of the four-element lumped parameter model by measuring the pulse wave waveform and the stroke volume of the radial artery, the compliance of the blood vessel is compared with the central part of the arterial system. It does not adopt a model that handles the peripheral part separately. Therefore, when a circulatory agonist was administered to a patient at the time of exercise or when a circulatory agonist was administered to a patient, the effect could not be evaluated separately for the central part and the peripheral part.

Next, the measurement of the blood pressure will be briefly described. A non-invasive blood pressure measurement device that has been generally used in the past has a cuff (arm band) attached to the upper arm or the like of a subject, applies pressure to the cuff, and detects the subject's pulse wave to measure the blood pressure value. Is measured. As described above, as an apparatus for measuring the blood pressure in the peripheral part of the subject, for example, JP-A-4-276234 is cited. That is, FIG.
As shown in FIG. 9, the cuff 110 is wound around and attached to the upper arm of the subject's upper limb, and the band 138 is attached to the wrist 1.
40, the pulse wave sensor 134 is brought into close contact with the radial artery of the subject, and the pulse wave of the subject is detected. Then, after the cuff 110 is pressurized, the systolic blood pressure value and the diastolic blood pressure value are measured by the well-known oscillometric method at the time of pressure reduction.

When the central blood pressure value and the peripheral blood pressure value in the arterial system of the human body are actually measured, there is a difference between the central blood pressure value and the peripheral blood pressure value, particularly regarding the systolic blood pressure value. Moreover, the degree of this difference varies depending on the shape of the pulse wave observed on the peripheral side. FIG. 22 to FIG. 24 show how the blood pressure value varies depending on the shape of the pulse wave.

These figures show the aortic pressure waveform and systolic / diastolic blood pressure values on the central side, and the radial artery pressure waveform and systolic / diastolic blood pressure values on the peripheral side. In the case of the pulse waveform of the first type shown in FIG. 22, the systolic blood pressure values obtained from the aortic pressure waveform shown by the dotted line and the radial artery waveform shown by the solid line are almost the same although the radial artery side is slightly higher. Good.

However, in the case of the pulse waveform of the second type shown in FIG. 23, the systolic blood pressure difference is 14.9 mmHg, which is different from that in the case of the pulse waveform of the first type shown in FIG. Then it gets pretty big. Furthermore, when the pulse waveform of the third type shown in FIG.
In addition to becoming even larger at 6.1 mmHg, the aortic pressure waveform as a whole greatly exceeds the radial artery waveform, contrary to the first and second types of pulse waveforms.

By the way, it can be seen from FIGS. 22 to 24 that the diastolic blood pressure value on the radial artery side is substantially the same regardless of the shape of the pulse wave. Here, the first
The third type of pulse wave will be briefly described. The first type of pulse waveform is a pulse of a normal healthy person, and the waveform is slow and relaxed, and is characterized by a constant rhythm and little disturbance.

[0012] The second type of pulse wave waveform is characterized in that it rapidly rises and then falls immediately, so that the aortic notch is deeply cut and the subsequent diastolic peak is considerably higher than usual. . The third type of pulse wave waveform is characterized in that it rapidly rises, does not immediately fall, and maintains a high blood pressure state for a certain period of time.

What follows from these illustrated figures is that
Even if the blood pressure on the peripheral side such as the radius and the upper arm is high, the blood pressure on the aortic root, that is, on the central side, may be low, and conversely, the blood pressure on the central side may be low even if the blood pressure on the peripheral side is low. The value can be high. Such a relation differs depending on the shape of the pulse waveform, and these relations appear in the shape of the pulse waveform.

For example, suppose that a hypotensive agent is administered to a patient for the treatment of hypertension, and the effect of the drug is observed based on the blood pressure in the radial artery. In such a case, even if the blood pressure measured on the peripheral side decreases, the blood pressure on the central side may not actually decrease. Therefore, it can be said that there are cases where it is difficult to correctly grasp the medicinal effect only from the peripheral blood pressure.

On the contrary, even if there is no change in blood pressure on the peripheral side, if the aortic pressure waveform changes and the blood pressure on the central side decreases, the burden on the heart is actually light. It is becoming. In such a case, even if the blood pressure on the peripheral side is not forcibly reduced, the effect of the drug is sufficiently exhibited, but it is difficult to judge this from only the blood pressure on the peripheral side.

By the way, conventionally, a myocardial load index (W-Product) has been used as an index for estimating the load on the myocardium. The myocardial load index WP is expressed as follows, where Pperi is the peripheral blood pressure and HR is the heart rate. WP = Pperi × HR

[0017]

As described above, even when the blood pressure on the peripheral side is high, the blood pressure on the aortic root, that is, the blood pressure on the central side may be low. Further, conversely, even when the peripheral blood pressure value is low, the central blood pressure value may be high, and the peripheral blood pressure value is not always linked to the central blood pressure value.

Although the myocardial load index should be used as an index to see how much the burden on the heart should be, the blood pressure value measured on the peripheral side as conventionally performed ( When the myocardial load index is calculated based on the systolic blood pressure, the burden on the heart may be overestimated, or conversely, underestimated.

Accordingly, a first object of the present invention is to provide a biological condition measuring device and a biological condition measuring method capable of accurately estimating a central blood pressure with a simple configuration.

It is a second object of the present invention to provide a biological condition measuring apparatus and a biological condition measuring method capable of calculating a more accurate myocardial load index WP corresponding to an actual myocardial load.

[0021]

According to a first aspect of the present invention, there is provided a measuring means for measuring a state of a living body including a general ejection period based on a pulse wave waveform of a peripheral part of the living body. Analysis means for calculating a circulatory parameter including viscoelasticity of an aorta as a circulatory parameter representing a circulatory dynamic of an arterial system from a central part to a peripheral part of the living body based on the state of the living body; Aortic blood pressure calculating means for calculating an estimated value of the aortic root blood pressure of the living body based on the circulatory parameters, the analyzing means,
In calculating the circulatory dynamic parameters, a left ventricular pressurization time calculated using the approximate ejection period as an initial value is used.

A second aspect of the present invention is an aortic blood pressure calculating means for calculating an estimated value of the aortic root blood pressure of the living body based on the peripheral blood pressure of the living body or the pulse wave waveform of the peripheral part of the living body, Heart rate detecting means for detecting the heart rate of the living body, and a myocardial load index calculating means for calculating a myocardial load index based on the estimated value of the aortic root blood pressure and the detected heart rate. Features.

According to a third aspect of the present invention, there is provided an aortic blood pressure calculating means for calculating an estimated value of the aortic root pressure of the living body based on a predetermined transfer function from a pulse wave waveform of a peripheral part of the living body,
Heart rate detecting means for detecting the heart rate of the living body, myocardial load index calculating means for calculating a myocardial load index based on the estimated value of the aortic root blood pressure and the detected heart rate,
It is characterized by having.

According to a fourth aspect of the present invention, in the first aspect, a heart rate detecting means for detecting a heart rate of the living body, and an estimated value of the aortic root blood pressure and the detected heart rate are used. A myocardial load index calculating means for calculating a myocardial load index.

According to a fifth aspect of the present invention, in the first aspect, a heart rate detecting means for detecting a heart rate of the living body based on the pulse wave waveform, an estimated value of the aortic root blood pressure and A myocardial load index calculating means for calculating a myocardial load index based on the detected heart rate.

According to a sixth aspect of the present invention, there is provided a measuring means for measuring the condition of the living body based on a pulse wave waveform at a peripheral part of the living body, and a central part to a peripheral part of the living body based on the state of the living body. Analysis means for calculating circulatory parameters including viscoelasticity of the aorta as circulatory parameters representing the circulatory dynamics of the arterial system leading to, and calculating an estimated value of the aortic root blood pressure of the living body based on the circulatory parameters Aortic blood pressure calculating means, a heart rate detecting means for detecting the heart rate of the living body, and a myocardial load index calculating means for calculating a myocardial load index based on the estimated value of the aortic root blood pressure and the detected heart rate And, it is characterized by having.

According to a seventh aspect of the present invention, in the configuration of the third aspect, the circulatory parameters include vascular resistance due to blood viscosity at the central portion, inertia of blood at the central portion, and blood inertia at the peripheral portion. It is characterized by including vascular resistance and viscoelasticity of blood vessels in the peripheral part.

According to an eighth aspect of the present invention, in the first aspect, the blood pressure calculating means includes a diode corresponding to an aortic valve,
The first corresponding to the vascular resistance due to blood viscosity in the central part
A first capacitance corresponding to the viscoelasticity of the aorta, a second resistance corresponding to the vascular resistance at the distal portion, A model having a second capacitance corresponding to the viscoelasticity of a blood vessel in the peripheral portion, wherein a series circuit of the diode and the first capacitance is connected between a pair of input terminals, A parallel circuit comprising the second capacitance and the second resistor is inserted between output terminals, and the first resistor and the second resistor are provided between both terminals of the first capacitance and the output terminal. The circulatory dynamics of the arterial system are modeled by a five-element lumped constant model in which a series circuit composed of the inductance is inserted, and the circulatory dynamics parameters are determined, and the voltage between both terminals of the first capacitance is determined. Let the waveform be the aortic pressure waveform , It is characterized in that.

According to a ninth aspect of the present invention, in the configuration according to any one of the first, fourth to eighth aspects, the state of the living body is a pulse wave in a peripheral portion of the arterial system. The calculating means is configured such that, when an electric signal corresponding to the left ventricular pressure of the living body is given between the input terminals, an electric signal corresponding to the pulse wave waveform is obtained from the output terminal. It is characterized in that the value of each element constituting the lumped parameter model is determined.

According to a tenth aspect of the present invention, there is provided the configuration according to any one of the first to fourth aspects, wherein
The state of the living body is a pulse wave in a peripheral portion of the arterial system, and has a strain calculation unit that calculates a strain of the pulse wave from a waveform of the pulse wave. The method is characterized in that the circulatory dynamic parameter is determined based on a correlation with a pulse wave distortion.

According to an eleventh aspect of the present invention, in the configuration according to any one of the first, fourth to tenth aspects, the stroke volume detecting means for detecting the stroke volume of the living body is provided. The blood pressure calculating means has a calculated value of stroke volume obtained from the aortic pressure waveform and an actual measured value of stroke volume measured by the stroke volume measuring means. Thus, the method is characterized in that the value of the circulatory dynamic parameter is adjusted.

According to a twelfth aspect of the present invention, in the configuration according to any one of the first, fourth to eleventh aspects, the work amount for calculating the work amount of the heart of the living body based on the aortic pressure waveform. It is characterized by having calculation means.

According to a thirteenth aspect of the present invention, in the configuration according to any one of the fourth to twelfth aspects, the variation rate of the detected heart rate with respect to a reference heart rate, which is a resting heart rate, is set in advance. A determination unit configured to determine whether or not a reference heart rate variability has been exceeded; wherein the myocardial load index calculating unit determines that the aortic origin is greater than the reference heart rate variability based on the determination. The myocardial load index is calculated based on the head blood pressure and the detected heart rate.

According to a fourteenth aspect of the present invention, in the configuration of the thirteenth aspect, there is provided a peripheral blood pressure detecting means for non-invasively detecting a peripheral blood pressure of the living body, and the myocardial load index calculating means comprises: When the variation rate is less than the reference heart rate variation rate based on the determination, a myocardial load index is calculated based on the peripheral blood pressure and the detected heart rate.

According to a fifteenth aspect of the present invention, in the first aspect, the myocardial load index calculating means is configured to determine the myocardial load index at a predetermined timing of the calculated circulatory parameters. When the rate of change for the reference circulatory parameters that is the circulatory parameters is equal to or greater than a preset parameter reference rate of change,
A myocardial load index is calculated based on the aortic root blood pressure and the detected heart rate.

[0036] According to a sixteenth aspect of the present invention, in the configuration of the fifteenth aspect, there is provided a peripheral blood pressure detecting means for non-invasively detecting a peripheral blood pressure of the living body, and the myocardial load index calculating means comprises: When the variation rate is less than the reference parameter variation rate based on the determination, a myocardial load index is calculated based on the peripheral blood pressure and the detected heart rate. 18. The configuration according to claim 17, wherein a measurement process of measuring a state of the living body including a general ejection period based on a pulse wave waveform of a peripheral part of the living body, and a central part of the living body based on the state of the living body An analysis process for calculating circulatory parameters including viscoelasticity of the aorta as circulatory parameters representing the circulatory dynamics of the arterial system from to the periphery,
Aortic blood pressure calculation process of calculating an estimated value of the aortic root blood pressure of the living body based on the circulatory parameters, the analysis process, when calculating the circulatory parameters, the approximate ejection period It is characterized in that the left ventricular pressurization time calculated as an initial value is used.

[0037] According to an eighteenth aspect of the present invention, there is provided a measuring process for measuring a state of the living body based on a pulse wave waveform of a peripheral part of the living body, and a central part to a peripheral part of the living body based on the state of the living body. An analysis process of calculating circulatory parameters including viscoelasticity of the aorta as circulatory parameters representing the circulatory dynamics of the arterial system, and aortic blood pressure calculating the aortic root pressure of the living body based on the circulatory parameters A calculating process, a heart rate detecting process for detecting a heart rate of the living body, and a myocardial load index calculating process for calculating a myocardial load index based on the aortic root blood pressure and the detected heart rate. It is characterized by.

According to a nineteenth aspect of the present invention, in the configuration of the eighteenth aspect, the variation rate of the detected heart rate with respect to a reference heart rate as a resting heart rate exceeds a preset reference heart rate variation rate. A myocardial load index calculation process, wherein the myocardial load index calculating process, when the fluctuation rate is equal to or more than the reference heart rate fluctuation rate based on the discrimination, the aortic root blood pressure and the detected A myocardial load index is calculated based on the heart rate.

The structure according to a twentieth aspect is characterized in that, in the structure according to the eighteenth aspect, there is provided a peripheral blood pressure detecting process for non-invasively detecting a peripheral blood pressure of the living body. When the variation rate is less than the reference heart rate variation rate based on the determination, a myocardial load index is calculated based on the peripheral blood pressure and the detected heart rate.

According to a twenty-first aspect, in the configuration of the seventeenth aspect, a heart rate detection process for detecting a heart rate of the living body is performed based on the estimated value of the aortic root blood pressure and the detected heart rate. A myocardial load index calculating process for calculating a myocardial load index.

According to a twenty-second aspect of the present invention, in the configuration of the seventeenth aspect, a heart rate detecting process for detecting a heart rate of the living body based on the pulse wave waveform, and an estimated value of the aortic root blood pressure and Calculating a myocardial load index based on the detected heart rate.

According to a twenty-third aspect of the present invention, in the biological condition measuring method according to any one of the seventeenth to twenty-second aspects, the myocardial load index calculating process includes the step of calculating the myocardial load index at a predetermined timing of the calculated circulatory parameters. When the rate of change with respect to a reference circulatory parameter that is a circulatory parameter is equal to or greater than a preset parameter reference change rate, a myocardial load index is calculated based on the aortic root blood pressure and the detected heart rate. And

According to a twenty-fourth aspect of the present invention, in the configuration of the twenty-third aspect, there is provided a peripheral blood pressure detecting process for non-invasively detecting a peripheral blood pressure of the living body, When the variation rate is less than the reference parameter variation rate based on the determination, a myocardial load index is calculated based on the peripheral blood pressure and the detected heart rate.

[0044]

Preferred embodiments of the present invention will now be described with reference to the drawings. First Embodiment Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

[1] Schematic Configuration of Blood Pressure Measurement Apparatus FIG. 1 is a block diagram showing the configuration of a blood pressure measurement apparatus as a biological condition measurement apparatus according to the first embodiment. In the first embodiment, based on the information obtained from the human body by the non-invasive sensor, the circulatory parameters of the arterial system of the human body are evaluated. The blood pressure, myocardial load index, and cardiac work are calculated, and the specific contents of the circulatory parameters will be described later.

As shown in FIG. 2, the pulse wave detecting device 1 detects a radial artery waveform via a pressure sensor S2 attached to the wrist of the subject, and detects the cuff band S1 attached to the upper arm of the subject. Detects the blood pressure of the subject via Then, the measured radial artery waveform is calibrated based on the blood pressure, and is output as an analog electric signal. This analog signal is A
The signal is input to a / D (analog / digital) converter 3 and is converted into a digital signal every predetermined sampling period.

As shown in FIG. 2, the stroke volume measuring device 2 is connected to a cuff band S1, and through this cuff band S1, the amount of blood flowing out of the heart in one pulse. Is 1
The stroke volume is measured, and the measurement result is output as digital stroke data as a digital signal. As this type of measuring device, an apparatus for performing measurement by a so-called systolic area method can be used.

The microcomputer 4 has a built-in waveform memory for storing the pulse waveform taken from the A / D converter 3 and a temporary storage memory as a work area.
The microcomputer 4 performs various processes as shown in FIG. 6 in accordance with a command input from the keyboard 5 which is an input device, and outputs a result obtained from these processes to the output device 6.

Here, only the outline of the processing will be described, and the details of the processing will be described in detail when describing the operation. Pulse Wave Measurement Data Reading Process (Step S1) a) A time-series digital signal of the radial artery waveform obtained via the A / D converter 3 is loaded into a built-in waveform memory (not shown). b) The radial artery waveform fetched into the waveform memory is averaged for each "beat" to obtain a radial artery waveform corresponding to one beat (hereinafter, referred to as an average waveform).

Process of reading stroke volume measurement data (Step S2) Loading of stroke volume data into temporary storage memory built in microcomputer 4 Parameter calculation process (Step S3) Radial artery waveform corresponding to one beat Is calculated, and each parameter of the electrical model corresponding to the arterial system is calculated based on this formula.

Data Calculation Process (Step S 4) A pulse wave waveform at the aortic root is obtained from the obtained circulatory parameters, and the systolic blood pressure, the diastolic blood pressure, the myocardial load index WP, and the heart rate at the aortic root are obtained. Calculate the workload. Output Process (Step S5) The obtained circulatory parameters, systolic blood pressure value, diastolic blood pressure value, myocardial load index WP, and work of the heart are output to the output device 6.

[2] Detailed Configuration of Output Device Next, details of the output device 6 will be described with reference to FIG. The measured blood pressure display unit 61 displays the systolic blood pressure, the diastolic blood pressure, and the average blood pressure that are actually measured based on the radial artery waveform.

The central part estimated blood pressure display part 62 displays the central part average blood pressure E01, systolic blood pressure Em ', and diastolic blood pressure Eo obtained by the processing described later. The warning display unit 63 is configured by a plurality of LEDs arranged in a horizontal line, and these LEDs light up in accordance with the difference between the actually measured systolic blood pressure and the central systolic blood pressure Em ′.

That is, if the difference between the two is ± 10 mmHg or less, the “NORMAL” green LED is turned on, and the difference is ± 1 mmHg.
When it exceeds 0 mmHg, the red LED of "CAUTION" is turned on.

The parameter display section 64 displays the capacitance Cc, the electric resistance Rc, the inductance L, the capacitance C, the electric resistance Rp, the left ventricle pressurizing time ts,
When the time tp of one beat, the stroke volume SV and the cardiac work Ws are supplied, these parameters are displayed. The details of these parameters will be described later. The CRT display 67 displays various waveforms such as a radial artery waveform, a left ventricular pressure waveform, and an aortic pressure waveform.

The printer 65 has a print command button 66
Is pressed, the various data displayed on the measured blood pressure display section 61, the central part estimated blood pressure display section 62, the warning display section 63, the parameter display section 64, and the waveform displayed on the CRT display 67 are printed on paper. Print out.

The myocardial load index display section 68 displays the myocardial load index WP obtained by the processing described later. Here, the significance of performing a warning display on the warning display unit 63 will be described.

As described above with reference to FIGS. 22 to 24, there are three types of the systolic blood pressure difference between the estimated aortic pressure waveform and the radial artery waveform. The subject whose pulse wave waveform is of the first type (FIG. 22) is likely to be a healthy person, and in the case of the second and third types, the subject often has some kind of disease.

For example, the second type (FIG. 23) is caused by abnormal blood flow, and is highly likely to have diseases such as edema, hepatic kidney disease, respiratory disease, gastrointestinal disease, and inflammatory disease. The third type is caused by an increase in the degree of blood vessel wall tension, and is likely to have hepatobiliary disease, skin disease, hypertension, painful disease, and the like.

Therefore, in the present embodiment, when the systolic blood pressure difference is considered to be abnormal, a red LED is turned on to display a warning. In addition,
In the above example, the diagnosis is made based on the systolic blood pressure difference between the aortic pressure waveform and the radial artery waveform. However, the diastolic blood pressure difference or the average blood pressure difference may be used instead of the systolic blood pressure difference. Furthermore, it goes without saying that the diagnosis may be made using all of the systolic blood pressure difference, the diastolic blood pressure difference and the average blood pressure difference.

[3] Five-Element Lumped Parameter Model In the first embodiment, a “five-element lumped parameter model” is newly adopted as an electrical model of the arterial system. In this five-element lumped parameter model, among the factors that determine the behavior of the circulatory system of the human body, Japanese Patent Application Laid-Open No. 6-205747 (Title of Invention:
Inertia due to blood in the central part, blood vessel resistance due to blood viscosity in the central part (viscous resistance), compliance of blood vessels in the peripheral part (viscoelasticity) used in the four-element lumped parameter model disclosed by the pulse wave analyzer) Aortic compliance was added as a new parameter to the four parameters of vascular resistance (viscous resistance)
One parameter is modeled as an electric circuit. Note that compliance is a quantity representing the softness of a blood vessel.

FIG. 3 (a) shows a circuit diagram of a four-element lumped parameter model, and FIG. 3 (b) shows a circuit diagram of a five-element lumped parameter model. Hereinafter, the correspondence between each element and each parameter constituting the five-element lumped parameter model will be described. Capacitance Cc: aortic compliance [cm5 / dyn] Electric resistance Rc: vascular resistance due to blood viscosity at the central part of the arterial system [dyn · s / cm5] Inductance L: inertia of blood at the central part of the arterial system [dyn · s2] / cm5] Capacitance C: blood vessel compliance at the peripheral part of the arterial system [cm5 / dyn] Electric resistance Rp: blood vessel resistance at the peripheral part of the arterial system due to blood viscosity [dyn · s / cm5]

Here, the currents i, ip, ic, and is flowing through the respective parts in the electric circuit correspond to the blood flowing through the corresponding parts.
Flow [cm3 / s]. Among them, the current i is the aortic blood flow, and the current is is the blood flow pumped from the left ventricle.
The input voltage e corresponds to the left ventricular pressure [dyn / cm2], and the voltage v1 corresponds to the aortic root pressure [dyn / cm2]. Further, the terminal voltage vp of the capacitance C corresponds to the pressure [dyn / cm2] at the radial artery. In addition, FIG.
The diode D shown in (b) corresponds to the aortic valve, and is turned on (the valve is open) during the period corresponding to the systole, and off (the valve is closed) during the period corresponding to the diastole. Becomes

As will be described later, in the first embodiment, these five parameters are not calculated at once, but the parameters other than the capacitance Cc are calculated by the four-element concentration disclosed in the above-mentioned document. After the calculation using the constant model, the capacitance Cc is determined. Therefore, first, the behavior of the four-element lumped parameter model shown in FIG. 3A will be theoretically described.

In the four-element lumped parameter model shown in FIG. 11A, the following differential equation is established. v1 = Rci + L (di / dt) + vp (1) Here, the current i can be expressed as follows: i = ic + ip = C (dvp / dt) + (vp / Rp) (2) ) Is transformed as follows: v1 = LC (d2vp / dt2) + {RcC + (L / Rp)} (dvp / dt) + {1+ (Rc / Rp)} vp (3)

As is well known, the general solution of the quadratic constant-coefficient ordinary differential equation represented by the equation (3) satisfies the special solution (stationary solution) satisfying the equation (3) and the differential equation represented by the following equation. Given by the sum of the transient solutions 0 = LC (d2vp / dt2) + {RcC + (L / Rp)} (dvp / dt) + {1+ (Rc / Rp)} vp (4)

Next, the solution of the differential equation (4) is obtained as follows. First, a damped oscillation waveform represented by the following equation is assumed as a solution of the differential equation (4). vp = exp (st) (5) When the equation (5) is substituted into the equation (4), the equation (4) is transformed as follows. [LCs2 + {RcC + (L / Rp)} s + {1+ (Rc / Rp)}] vp = 0 (6)

When equation (6) is solved for s, s = [− {RcC + (L / Rp)} ± {RcC + (L / Rp)} 2-4LC {1+ (Rc / Rp)}] / 2LC (7) In the equation (7), when {RcC + (L / Rp)} 2 <4LC {1+ (Rc / Rp)} (8), the value in the root of the second term is negative, and s is It looks like this: s = [− {RcC + (L / Rp)} ± j} (4LC ｛1+ (Rc / Rp)｝ − {RcC + (L / Rp)｝ 2)] / 2LC = −α ± jω (9)

Here, the attenuation factor is α and the angular frequency is ω, and α = {RcC + (L / Rp)} / 2LC = (L + RpRcC) / 2LCRp (10) ω = [{4LC ｛1+ (Rc / Rp)｝-{RcC + (L / Rp)｝ 2}] / 2LC (11). A1 = LC (12) A2 = (L + RcRpC) / Rp (13) A3 = (Rc + Rp) / Rp (14) Equations (10) and (11) are expressed as follows. be able to. α = (A2 / 2A1) (15) ω = {(A3 / A1) −α2} (16)

As described above, the value of s is determined, and a solution satisfying the differential equation (4) is obtained. Based on the above findings, Equation (5) can be used as an equation that approximates the damped oscillation component included in the response waveform of the four-element lumped parameter model. Next, the pressure waveform at the aortic root is modeled. Generally, the pressure waveform at the aortic root is shown in FIG.
The time tp in the figure is the time for one beat of the waveform, and the time ts is the pressurization time of the left ventricle. In the four-element lumped parameter model, this pressure waveform is approximated by a triangular wave shown in FIG. Assuming that the amplitude and time of the approximate waveform are represented by Eo, Em, tp, tp1 in FIG. 5, the aortic pressure v1 at an arbitrary time t is represented by the following equation. Here, Eo is the diastolic blood pressure (diastolic blood pressure), Em is the pulse pressure, (Eo + Em) is the systolic blood pressure (systolic blood pressure), tp is the time of one beat, tp1 is the pressure from the rise of the aortic pressure to the diastolic blood pressure value. It is time to become. 0 ≦ t
<Section of tp1: v1 = Eo + Em {1- (t / tp1)} (17) Section of tp1 ≦ t <tp: v1 = Eo (18)

The response waveform vp (ie, the radial artery wave) when the voltage v1 represented by the equations (17) and (18) is input to the equivalent circuit of FIG. 3A is as follows.
Section of 0 ≦ t <tp1: vp = Emin + B (1−t / tb) + Dm1exp (−αt) · sin (ωt + θ1) (19) Section of tp1 ≦ t <tp: vp = Emin + Dm2 · exp ｛−α (t −tp1)｝ × sin ｛ω (t-tp1) + θ2｝ (20)

Here, Emin is the lowest blood pressure value in the radial artery waveform measured by the pulse wave detector 1 (see FIG. 11 described later). The third term on the right-hand side in equation (19) and the second term on the right-hand side in equation (20) are the damped vibration components of equation (5), and α and ω in these terms are expressed by equations (15) and ( 16). In addition, B,
tb, Dm1, and Dm2 are constant values calculated according to a procedure described later.

Next, among the constants in the equations (19) and (20), those other than the already determined α and ω will be examined.
First, when the equations (17) and (19) are substituted into the differential equation (3), the following equation is obtained. Eo + Em {1- (t / tp1)} = {1+ (Rc / Rp)} (Emin + B)-(B / tb) @ RcC + (L / Rp) @ t + {LC (.alpha.2-.omega.2) Dm1-.alpha.Dm1@RcC+ (L / Rp)｝ + Dm1 ｛1+ (Rc / Rp)｝｝ exp (-αt) sin (ωt + θ1) + ｛ωDm1 ｛RcC + (L / Rp)｝-2LCαωDm1｝ exp (-αt) cos (ωt + θ1) …(twenty one)

The following conditions are required to satisfy the expression (21). Eo + Em = {1+ (Rc / Rp)} (Emin + B) = Eo + A3B- (B / tb) A2 (22) (Em / tp1) = (B / tb) {1+ (Rc / Rp)} = (A3B / tb) ) (23) LC (α2-ω2) -α {RcC + (L / Rp)} + (1 + Rc / Rp) = 0 (24) RcC + (L / Rp) = 2LCα (25)

Equations (24) and (25) represent α and ω
However, α and ω already obtained by Expressions (15) and (16) satisfy these expressions. On the other hand, when the equations (18) and (20) are substituted into the differential equation (3), the following equation is obtained. Eo = {1+ (Rc / Rp)} Emin + [LC (α2-ω2) Dm2-α−RcC + (L / Rp) pDm2 + ｛1+ (Rc / Rp)｝ Dm2] · exp ・ -α (t- tp1)｝ sin ｛ω (t-tp1) + θ2｝ + [ω ｛RcC + (L / Rp)｝ Dm2-2 LCαωDm2] expｅｘ-α (t-tp1)｝ cos ｛ω (t-tp1) + θ2｝ ... (26)

In order to satisfy the equation (26), it is necessary that the following equation be satisfied in addition to the equations (24) and (25). Eo = {1+ (Rc / Rp)} Emin = A3Emin (27) Next, the conditional expression (22) for establishing the differential equation (3)
The constants of Expressions (19) and (20) are calculated based on (25) and (27).

First, Emin is obtained from equation (27) as follows. Emin = (EO / A3) (28) From equation (23), B is as follows: B = (tbEm) / (tp1A3) (29) By substituting equation (29) into equation (22) and solving for tb, tb = (tp1A3 + A2) / (A3) (30)

Further, the remaining constants Dm1, Dm2, θ1, θ2
Is selected so that the radial artery waveform vp can maintain continuity at t = 0, tp1, tp, that is, a value that satisfies the following condition (1). That vp (tp1) in equation (19) matches vp (tp1) in equation (20) vp (tp) in equation (20) matches vp (0) in equation (19) Equation ( The differential coefficient of t = tp1 in equation (19) and equation (20) agrees with the differential coefficient of equation (19) at t = 0 and t = tp1 in equation (20).
The differential coefficients at tp match

That is, Dm1 and θ1 are selected as follows: Dm1 = √ (D112 + D122) / ω (31) θ1 = tan-1 (D11 / D12) (32) Here, D11 = (vO1−B−Emin) ω (33) D12 = (vO1−B−Emin) α + (B / tp) + (iO1 / C) (34) where vO1 and iO1 are t = Initial values of vp and ic at 0.

Dm2 and θ2 are selected as follows: Dm2 = √ (D212 + D222) / ω (35) θ2 = tan-1 (D21 / D22) (36) Where D21 = (vO2−Emin) · ω (37) D22 = (vO2−Emin) · α + (iO2 / C) (38) where vO2 and iO2 are the initial values of vp and ic at t = tp1 Value.

In this way, the constants of the equations (19) and (20) were obtained. Now, by performing an inverse calculation from the angular frequency ω in the equation (16), the blood vessel resistance RC is as follows: Rc = [L−2Rp {LC (1−ω2LC)}] / CRp (39) Here, the condition that Rc is a real number and positive is as follows: {4Rp2C} / {1+ (2ωRpC) 2} ≦ L ≦ (1 / ω2C) (40)

Generally, Rp is about 10 3 [dyn · s / cm 5],
C is about 10 -4 [cm5 / dyn] and ω is the angular frequency of the vibration component superimposed on the pulse wave, so that 10 (rad / s)
That is all. Therefore, the lower limit of equation (40) can be regarded as approximately 1 / (ω2C). So, for simplicity,
If L is approximately set as follows: L = 1 / (ω2C) (41), Rc becomes Rc = L / (CRp) (42).

From the relationship between the equations (41) and (42), the attenuation constant α in the equation (15) is as follows: α = 1 / (CRp) (43) Using the relations of Equations (41) to (43), α, ω,
When the remaining parameters of the four-element lumped model are represented by L, Rc = αL (44) Rp = (ω2L / α) (45) C = 1 / (ω2L) (46) From these equations (44) to (46), it is clear that the parameters are determined by obtaining α, ω, and L.

Here, as will be described later, α, ω, B, tb
Is obtained from the measured waveform of the radial artery wave, and L is the stroke volume S
It can be calculated based on V. Hereinafter, a calculation procedure of L based on the stroke volume SV will be described. First, the average value E01 of the pressure wave at the aortic root is given by the following equation. E01 = {Eotp + (tp1Em / 2)} / tp (47) On the other hand, the following equation holds among Rc, Rp, α, ω, and L. Rc + Rp = αL + (ω2L / α) = (α2 + ω2) L / α (48)

Since the average current flowing through the four-element lumped parameter model, that is, the average value E01, divided by (Rc + Rp) corresponds to the average value (SV / tp) of the blood flow flowing through the artery due to pulsation. And the following equation holds. SV / tp = (α) / {(α2 + ω2) L} (1 / tp) {Eotp + (tp1Em / 2)} (49)

By solving the equation (49) thus obtained with respect to L, an equation for obtaining L from the stroke volume SV is obtained as follows. L = α ｛{Eotp + (tp1Em / 2)} / {(α2 + ω2) SV} (50) By measuring the blood flow, the average current (1 / tp) ｛Eotp + (tp1Em / 2) A value corresponding to｝ may be determined, and the inductance L may be calculated based on the result. Known devices for measuring blood flow include those based on the impedance method and those based on the Doppler method. In addition, examples of the Doppler blood flow measuring device include a device using an ultrasonic wave and a device using a laser.

[4] Explanation of the Principle of the Method of Calculating the Circulation Kinetic Parameters Next, the principle of the method of calculating the circulatory dynamic parameters based on the five-element lumped parameter model will be described. As mentioned earlier, Rc, Rp, C, L
Is determined using the four-element lumped model, and the value of the capacitance Cc is determined based on these parameters. Therefore, the current i and the current i in FIG.
It is necessary to determine s, voltage v1, voltage vp, and the like.

First, the left ventricular pressure waveform e is approximated by a sine wave as shown in FIG. That is, assuming that ωs = π / ts, the left ventricular pressure waveform e is expressed by the following equation. e = Em 'sinωst (51) where Em' is the systolic blood pressure, and in FIG.
+ Eo). Hereinafter, as shown in FIG.
Will be described separately for a systole of t1 ≦ t <t2 and a diastole of t2 ≦ t <(tp + t1). Here, time t1 and time t2 are times at the intersection of the left ventricular pressure waveform and the aortic pressure waveform.

[4.1] Systole In this case, v1 = e is satisfied, and equations (1) and (2) are satisfied for voltage v1 and current i, respectively. Therefore, the following differential equation is established from Expressions (1) to (3) and Expressions (12) to (14) and Expression (51). A1 (d2vp / dt2) + A2 (dvp / dt) + A3vp = Em'sin ωst (52)

First, a steady-state solution vpst of this differential equation is obtained in the same manner as in the four-element lumped parameter model. For this purpose, a stationary solution vpst is assumed as in the following equation. vpst = E1cosωst + E2sinωst (53) By substituting equation (53) into vp of equation (52) and comparing the coefficients, the following two equations are obtained. (A3.ωs2A1) E1 + ωsA2E2 = 0 (54) −ωsA2E1 + (A3−ωs2A1) E2 = Em ′ (55)

By solving these equations, E1 = (− ωsA2Em ′) / {(ωsA2) 2+ (A3−ωs2A1) 2} (56) E2 = {(A3−ωs2A1) Em ′} / ｛(ωsA2) ) 2+ (A3−ωs2A1) 2｝ (57)

Next, the transient solution vpt of the differential equation of equation (52)
Find r. For this purpose, vptr = exp (λt), and substitutes for vp in the following equation. A1 (d2vp / dt2) + A2 (dvp / dt) + A3vp = 0 (58) Thus, the following equation is obtained. A1λ2 + A2λ + A3 = 0 (59)

Then, when this equation is solved for λ, the following equation is obtained. λ = {-A2 ± {(A22-4A1A3)} /
(2A1) = ｛− A2 / (2A1)｝ ± √ [｛A2 / (2A
1)｝ 2- (A3 / A1)] ... (60)

Here, {A2 / (2A1)} 2 <(A3 / A
If 1) (vibration mode), the following equation is obtained. λ = −A2 / (2A1) ± j√ [(A3 / A1) − {A2 / (2A1)｝ 2] = − β1 ± jω1 (61)

At this time, β1 = A2 / (2A1) (62) ω1 = √ (A3 / A1-β12 (63)

Here, the transient solution vptr is set as in the following equation. vptr = (a1cosω1t + ja2sinω1t) exp (−β1t) (64) Then, since the voltage vp is represented by the sum of the steady-state solution and the transient solution, the voltage vp is given by the following equation by the equations (53) and (64). vp = (E1cosωst + E2sinωst) + (a1cosω1t + ja2sinω1t) exp (−β1t) (65)

The current i is obtained by substituting equation (65) into equation (2) as follows: i = (E1 / Rp + ωsCE2) cosωst + (− ωsCcE1 + E2 / Rp) sinωst + [[｛(1−β1CRp) / Rp｝ cosω1t−ω1Csinω1t] a1 + j [ω1Ccosω1t + ｛(1-β1CRp) / p (1−p) β1t)… (67)

Next, when t = t1, vp and i are respectively set to v0
2, i0 is assumed as follows. i0 = J0 + (a1J1 + ja2J2) exp (-. beta.1t1) ... (68) v02 = P0 + (a1P1 + ja2P2) exp (-. beta.1t1) (69) Then, the following equations are established from the equations (65) to (69). J0 = (E1 / Rp + ωsCE2) cosωst1 + −ωsCE1 + E2 / Rp) · sinωst1 ... (70) J1 = s (1-β1CRp) / Rp ｛cosω1t1−ω1Csinω1t1 ... (71) .. (72) P0 = E1cosωst1 + E2sinωst1 (73) P1 = cosω1t1 (74) P2 = sinω1t1 (75)

Further, when Equations (68) to (69) are solved for a1 and a2, the following is obtained. a1 = [{(v02−P0) J2− (i0−J0) P2} / (J2P1−J1P2)] exp (β1t1) (76) a2 = [（− (v02−P0) J1 + (i0−J0) P1｝ / {j (J2P1-J1P2)}] · exp (β1t1) (77)

Further, it can be seen from the equations (71) to (75) that the following equation holds. J2P1−J1P2 = ω1C (78) Therefore, substituting the equations (76) to (77) into the equation (64),
When equation (78) is used at that time, the following equation is obtained as the transient solution vptr. vptr = [(v02−P0) cosω1 (t−t1) − [{(1−β1CRp) · (v02−P0) −Rp (i0−J0)} sinω1 (t−t1)}] / (ω1CRp)] exp (β1t1) exp (−β1t) ... (80)

Here, B1tr = v02−P0 (81) t ′ = t−t1 (82) B2tr = − {(1−β1CRp) (v02−P0) −Rp (i0−J0)} / (ω1CRp) (83), vptr = (B1trcosω1t ′ + B2trsinω1t ′) exp (−β1t ′) (84)

After all, equation (65) becomes as follows. vp = (E1cosωst + E2sinωst) + (B1trcosω1t ′ + B2trsinω1t ′) exp (−β1t ′) (85)

Next, in the above equation (67), D1st = (E1 / Rp) + ωsCE2 (86) D2st = −ωsCE1 + (E2 / Rp) (87) D1tr = ｛(1-β1CRp) / Rp｝ B1tr + ω1CB2tr .. (88) D2tr = −ω1CB1tr + ｛(1−β1CRp) / Rp｝ B2tr (89)

Then, as the current i, i = (D1stcosωst + D2stsinωst) + (D1trcosω1t ′ + D2trsinω1t ′) exp (−β1t ′) (90) is obtained.

The current is is obtained as follows: is = Cc (dv1 / dt) + i = ωsCcEm'cosωst + i (91)

[4.2] Diastole In the diastole, the diode D is turned off, the left ventricular pressure e is not applied to the circuit on the cathode side of the diode D, and the current flowing through the capacitance CC is the current The magnitude is equal to i and the current is in the opposite direction. Therefore, the voltage v1
Is represented by the above equation (1), and the current i and the current ic are respectively represented by the following equations. i = -Cc (dv1 / dt) (92) ic = C (dvp / dt) (93)

Therefore, the voltage vp is as follows: vp = Rp (i−ic) = − Rp {Cc (dv1 / dt) + C (dvp / dt)} (94)

Since i-ic = ip = vp / Rp, i = vp / Rp + C (dvp / dt) (95)

Next, the following equation is obtained by substituting the equation (95) into the equation (1) and differentiating both sides of the obtained equation with time t.
You. dv1 / dt = LC (d3vp / dt3) + (L / Rp + CRc) (d2vp / dt2) + (Rc / Rp + 1) (dvp / dt) (96)

The following equation is derived from equations (92) and (95). dv1 / dt =-{vp / Rp + C (dvp / dt)} / Cc (97) Then, the following expression is obtained from Expression (96) and Expression (97). LC (d3vp / dt3) + {(L + CRcRp) / Rp} (d2vp / dt2) + {(CcRc + CcRp + CRp) / CcRp} (dvp / dt) + {1 / (CcRp)} vp = 0 ... (98)

Therefore, when this equation is modified, the following equation is obtained. (D3vp / dt3) + A1 '(d2vp / dt2) + A2' (dvp / dt) + A3'vp = 0 (99) where: A1 '= (L + CRcRp) / (LCRp) ... (100) A2' = (CcRc + CcRp + CRp) ) / (LCcCRp) (101) A3 '= 1 / (LCcCRp) (102)

Next, the following equation is obtained by substituting vp = exp (λt) into equation (99). (Λ3 + A1′λ2 + A2′λ + A3 ′) exp (λt) = 0 (103) Furthermore, the following definition is made. p = (A1'2 / 9)-(A2 '/ 3) (104) q = -A1'3 / 27 + (A1'A2') / 6-A3 '/ 2 (105) u = {q +} (Q2−p3)｝ 1/3 (106) v = ｛q−√ (q2−p3)｝ 1/3 (107) α ′ = − (u + v) + A1 ′ / 3 (108) β2 = ( u + v) / 2 + A1 '/ 3 (109) ω2 = (uv) √ (3) / 2 (110) λ1 = −α ′ (111) λ2 = −β2 + jω2 (112) λ3 = −β2− jω2 (113) If (q2−p3)> 0, the vibration mode is set.

The voltage vp is further assumed as follows. vp = b1exp (−α′t) + b2exp {(− β2 + jω2) t} + b3exp {(− β2−jω2) t} (114)

Then, by substituting equation (114) into equation (95), current i is transformed as follows. i = g0b1exp (−α′t) + (g1 + jg2) b2exp {(− β2 + jω2) t} + (g1−jg2) b3exp {(− β2−jω2) t} (115)

Here, g0 = (1−α′CRp) / Rp (116) g1 = (1−β2CRp) / Rp (117) g2 = (ω2CRp) / Rp (118)

Therefore, the voltage v1 is as follows from the equation (115). v1 = − (1 / CC) {idt = f0b1exp (−α′t) + (f1 + jf2) b2exp ｛(− β2 + jω2) t} + (f1−jf2) b3exp {(− β2−jω2) t} (119) )

Here, f0 = g0 / (α′Cc) (120) f1 = (β2g1-ω2g2) / {(β22 + ω22) Cc} (121) f2 = (ω2g1 + β2g2) / {(β22 + ω22) Cc} (122) Next, in order to simplify the calculation, in the following description, the time t2 shown in FIG. 4 is set to t = 0. Assuming that the voltage v1, the voltage vp, and the current i at t = 0 are v01, v02, and i0, respectively, these are expressed by the equations (119) and (11).
4), the following is obtained by setting t = 0 in equation (115). v01 = f0b1 + (f1 + jf2) b2 + (f1-jf2) b3 (123) v02 = b1 + b2 + b3 (124) i0 = g0b1 + (g1 + jg2) b2 + (g1-jg2) b3 (125)

Next, by modifying the second and third terms in equation (114), the voltage vp becomes as follows. vp = b1exp (-α't) + ｛(b2 + b3) cosω2t + j (b2−b3) sinω2t｝ exp (−β2t) = B0exp (−α′t) + (B1cosω2t + B2sinω2t) exp (−β2t) ... (126)

Here, B0 = b1 = v02- (k1g2-k2f2) / (k4g2-k3f2) (127) B1 = b2 + b3 = (k1g2-k2f2) / (k4g2-k3f2) (128) B2 = j ( b2-b3) = (k2k4-k1k3) / (k4g2-k3f2) (129) where k1 = v01-f0v02 (130) k2 = i0-g0v02 (131) k3 = g1-g0 (132) K4 = f1−f0 (133)

Next, by substituting vp in equation (126) into equation (2), the current i becomes as follows. i = D0exp (−α′t) + (D1cosω2t + D2sinω2t) exp (−β2t) (134) where D0 = ｛(1−α′CRp) / Rp｝ B0 (135) D1 = ｛(1−β2CRp ) / Rp｝ B1 + ω2CB2 (136) D2 = −ω2CB1 + ｛(1-β2CRp) / Rp｝ B2 (137)

Therefore, from the equation (134), the voltage v1 is as follows: v1 = − (1 / CC) ∫idt = H0exp (−α′t) + (H1cosω2t + H2sinω2t) exp (−β2t) (138) Here, H0 = D0 / (α′Cc) (139) H1 = (β2D1 + ω2D2) / {(β22 + ω22) Cc} (140) H2 = (− ω2D1 + β2D2) / {(β22 + ω22) Cc} (141)

As described above, in the above description, the time t2
Was set to t = 0. Then, in order to adjust the time scale, t → (tt−2) is replaced. As a result, the voltage v1, the voltage vp, and the current i are calculated by the equations (138) and (1
26) and from equation (134) are obtained as follows. v1 = H0exp {-α '(t-t2)} + {H1cos.omega.2 (t-t2) + H2 sin.omega.2 (t-t2)}. exp {-. beta.2 (t-t2)} = H0exp @-. alpha.' (t-t2) ＋ + [Hmsin ｛ω2 (t-t2) +｝ 21｝] · exp ｛-β2 (t-t2)… (142) vp = B0exp ｛-α '(t-t2) ｛+ ｛B1 cos ω2 (t-t2) + B2 sin ω2 (t−t2)｝ · exp {−β2 (t−t2)} = B0exp {−α ′ (t−t2)} + [Bmsin {ω2 (t−t2) + φ22}] exp {−β2 ( (t−t2)｝ (143) i = D0exp ｛−α ′ (t−t2)｝ + {D1cosω2 (t−t2) + D2sinω2 (t−t2)} · exp {−β2 (t−t2)} = D0exp {−α ′ (t−t2)} + [Dmsin {ω2 (t−t2) + φ23}] exp {−β2 (t−t2)} (144)

Here, Hm = √ (H12 + H22) (145) φ21 = tan-1 (H1 / H2) (146) Bm = √ (B12 + B22) (147) φ22 = tan-1 (B1 / B2) ... (148) Dm = √ (D12 + D22) ... (149) φ23 = tan-1 (D1 / D2) ... (150)

Incidentally, the current is in the diastole is “0”. Next, the theoretical value of the stroke volume SV is determined. Since the stroke volume SV is given by the area of the current is in the systole, it is obtained by integrating the current is expressed by the equation (91) from time t1 to time t2.
That is, SV = {t1t2isdt = {(ωSCCEm ′ + D1st) / ωS} (sinωSt2−sinωSt1) − (D2st / ωS) (cosωSt2−cosωSt1) + [exp ｛−β1 (t2−t1)} / (β12 + ω) {-(Β1D1tr + ω1D2tr) cosω1 (t2-t1) + (ω1D1tr-β1D2tr) sinω1 (t2-t1)} + (β1D1tr + ω1D2tr) / (β12 + ω12) (151)

[5] Operation of Pulse Wave Analysis Apparatus Next, the operation of the pulse wave analysis apparatus according to the present embodiment will be described with reference to FIGS. 6 to 10 are flowcharts showing the operation of the pulse wave analyzer according to the first embodiment.

FIG. 11 shows a waveform chart of an average waveform obtained by the above-mentioned averaging process. Further, in FIG.
FIG. 9 shows a waveform diagram in which a radial artery waveform obtained by a parameter calculation process described later is compared with an average waveform obtained by an averaging process. The operation will be described below with reference to these drawings.

Pulse Wave Measurement Data Reading Processing (Step S1) (a) Pulse Wave Reading Processing When evaluating the circulatory dynamic parameters, the diagnostician in charge of the subject's diagnosis uses the cuff band S1 as shown in FIG. The subject wears the pressure sensor S2 and inputs a command to start measurement from the keyboard 5. The microcomputer 4 sends a pulse wave measurement instruction to the pulse wave detector 1 in response to this command. As a result, the pulse wave detection device 1 detects the radial artery wave, and the A / D converter 3 outputs a time-series digital signal representing the radial artery wave. The microcomputer 4 takes this digital signal into a built-in waveform memory for a fixed time (about one minute). In this manner, the radial memory for a plurality of beats is loaded into the waveform memory.

(B) Averaging Processing Next, the microcomputer 4 superimposes the radial artery waveforms for a plurality of beats on a beat-by-beat basis, and obtains an average waveform per beat for the above-mentioned fixed time. Then, the average waveform is stored in the internal memory as a representative waveform of the radial artery waveform. The representative waveform W1 of the average waveform thus created
Is illustrated in FIG.

Single stroke volume data acquisition process (step S2) Next, the microcomputer 4 sets the stroke volume measuring device 2
To send a stroke volume measurement instruction. As a result, the stroke volume measuring device 2 measures the stroke volume of the subject, and the measurement result is taken into the built-in temporary memory by the microcomputer 4.

Parameter Calculation Process (Step S3) Next, based on the four-element lumped parameter model, of the five circulating parameters constituting the five-element lumped parameter model, the four circulating parameters except the capacitance Cc are obtained. Make a decision.

The microcomputer 4 executes a parameter calculation processing routine shown in FIGS. that time,
Along with the execution of this routine, an α, ω calculation processing routine shown in FIG. 9 is executed (steps S109 and S117).
You. Further, along with the execution of the α, ω calculation processing routine, the ω calculation routine shown in FIG. 10 is executed (step S203).

The processing contents of these routines will be described below. First, the microcomputer 4 is configured as shown in FIG.
For the average waveform of the radial artery as shown in FIG. 7, a time t1 'corresponding to the first point P1 at which the blood pressure becomes maximum, a blood pressure value y1, and a time t2' corresponding to the second point at which the blood pressure temporarily drops after the first point. The blood pressure value y2, the time t3 'corresponding to the third point P3, which is the second peak point, the blood pressure value y3, the time tp for one beat, and the diastolic blood pressure value Emin (the above expression (3) and expression (4) (Corresponding to the first term) (step S101).

If the pulse wave is "smooth" and it is difficult to distinguish the second point P2 and the third point P3, the time of the second point and the time of the third point are each set to t2 '.
= 2t1 'and t3' = 3t1 '. Next, in order to simplify the processing, the blood pressure values y1 to y3 are normalized using the blood pressure value y0 at point A shown in FIG. 13 (step S1).
02, S103), the value of point B is initialized to (y0 / 2) -0.1 (step S104).

Next, B, tb,
Determine the optimal values of α and ω. (A) First, B is changed in the range of "(y0 / 2) to y0", and at the same time, tb is changed in the range of "(tp / 2) to tp". At this time, B and tb are both +0.
Change at one interval. Then, for each of B and tb, α and ω that minimize | vp (t1 ')-y1 |, | vp (t2')-y2 |, and | vp (t3 ')-y3 |

(B) B, tb, obtained in (a)
B, tb, α, and ω in which | vp (t1 ′) − y1 |, | vp (t2 ′) − y2 |, and | vp (t3 ′) − y3 |

(C) On the basis of B and tb obtained in (b), within the range of B ± 0.05 for B and tb ± 0.05 for tb, the above (a) and (b) Re-execute the process.

(D) In the processes (a) to (c),
α is changed in the range of 3 to 10 at intervals of 0.1, and the optimum ω is calculated for each α. Further, ω is obtained by using the dichotomy method for the point where dvp (t2 ′) / dt = 0 at each α (see the flowchart of FIG. 10).

In calculating the value of vp in each of the above-mentioned processes, the initial value vo1 of the equation (33) is set to zero. Through the above processing, B, tb, α, and ω are finally determined.

(E) tp1, Em, and Eo are calculated based on equations (28) to (30) and equations (44) to (46) (steps S123 and S124). (F) Using equation (50), the value of L is calculated based on the measured stroke volume SV (step S125), and the remaining parameters Rc, Rp, and C are calculated using equations (44) to (44). 46) (step S126).

Next, based on the five-element lumped parameter model,
The capacitance Cc, which is the last circulation dynamic parameter, is determined. At this time, a method of determining the capacitance Cc so that the calculated value of the stroke volume SV matches the actually measured value, and a method of determining the capacitance Cc so that the diastolic blood pressure of the calculated pulse wave matches the diastolic blood pressure of the actually measured pulse wave. A method of determining the capacitance Cc is considered. Therefore, each method will be described separately for each case.

-1 Method of Determining the Capacitance Cc (Aortic Compliance) so that the Calculated Value of the Stroke Volume SV and the Measured Value Match First, First, the Calculated Value of the Stroke Volume SV and the Measured Value A description will be given of a specific method for determining the capacitance Cc so as to match. First, the value of the capacitance Cc is calculated based on the capacitance C calculated by the four-element lumped constant model.
It is estimated as in the following equation. The values of other circulatory parameters, ie, Rc, Rp, C, and L, obtained by the four-element lumped model are used. Cc = 10 · C (153) Next, using these circulatory parameters, the calculated value of the stroke volume SV is calculated by the equation (152).

At this time, the left ventricular pressurization time ts is estimated from the following equation from the time tp of one beat obtained by the four-element lumped parameter model. ts = (1.52-1.079tp) tp (154) This relational expression is an empirical expression obtained from the result of measuring the contraction time of the left ventricle by echocardiography, and as shown in FIG. -0.882 is obtained as the correlation coefficient. For the systolic blood pressure Em ', a value obtained by a four-element lumped parameter model is used (see equations (22) and (28)).

The times t1 and t2 can be determined from the relationship of left ventricular pressure = aortic pressure. Further, as described above, v02 and i0 are vp at t = t1,
Since it is the value of i, v02 and i0 can be obtained by substituting t1 into t existing in the equations (85) and (90).
Next, the value of the capacitance Cc is determined so that the calculated stroke volume SV calculated as described above matches the measurement value taken from the stroke volume measuring device 2. That is, the value of the capacitance Cc is changed within a predetermined range from the initial value obtained by the equation (153). And the measured value of stroke volume,
By comparing the calculated value calculated from the value of each capacitance Cc, it is checked whether or not the integer part of the measured value matches the integer part of the calculated value. If a match is found in the integer part, it is considered that the measured value and the calculated value match, and the capacitance Cc
Is determined, and the parameter calculation process ends.

On the other hand, if the measured value and the calculated value of the stroke volume do not agree with each other only by adjusting the value of the capacitance Cc, one of the values of the adjusted capacitance Cc is not included. The value of the capacitance Cc at which the difference between the measured value of the stroke volume and the calculated value is the minimum is defined as the final value. Next, the value of the systolic blood pressure Em 'is changed every 1 mmHg within the range of ± 3 mmHg, and it is checked whether the measured value of the stroke volume matches the calculated value in the same manner as described above. If there is a matching systolic blood pressure Em ', the value is set as the final systolic blood pressure Em', and the parameter calculation process ends.

On the other hand, even if the value of systolic blood pressure Em 'is adjusted,
If the measured value and the calculated value of the stroke volume have not yet been matched, the value of the resistance Rp is further adjusted. Thus, among the adjusted systolic blood pressure values Em ', the value of the systolic blood pressure value Em' in which the difference between the measured value of the stroke volume and the calculated value is the smallest is determined as the final value. Next, the resistance Rp is set to, for example, 10 [d
yn · s / cm5], and the value of the smallest difference between the measured value of the stroke volume and the calculated value is determined as the final value of the resistance Rp.

FIG. 31 shows an example of a flowchart for realizing the above-described process. Note that, for parameters that are varied within a predetermined range in the program, the original parameter name is appended with a subscript “v”.

-2 Method of Determining the Capacitance Cc so that the Diastolic Blood Pressure of the Calculated Pulse Wave and the Diastolic Blood Pressure of the Actually Measured Pulse Wave Are Next. A method of determining the capacitance Cc so that they match will be described. In this case, conventionally, the capacitance Cc is determined using the systolic time QT as an initial value.

As a method of calculating the systolic time QT used as the initial value, conventionally, the systolic time QT is obtained in advance from the subject's electrocardiogram, or the systolic time QT is obtained from the heart rate HR obtained from the electrocardiogram or the pulse wave waveform. Or by using a regression equation for determining Then, the left ventricle pressurization time tsv is set to “QT +
0.1 [sec] ”to“ QT + 0.2 [sec] ”, and at intervals of“ 0.01 [sec] ”, the systolic blood pressure Emv ′ is simultaneously changed from“ Eo + Em−20 [mmHg] ”to“ Eo + Em ”.
+20 [mmHg] ”at intervals of“ 1 mmHg ”, that is, 451 combinations are assumed for each of the left ventricular pressurization time tsv and systolic blood pressure Emv ′. The capacitance C such that the diastolic blood pressure of the pulse wave matches the diastolic blood pressure of the actually measured pulse wave.
It was configured to calculate c.

However, in the above-mentioned conventional method of obtaining the systolic time QT from the electrocardiogram, it is necessary to collect the electrocardiogram in advance, and there has been a problem that the device configuration becomes large and complicated. Further, in the method of obtaining the contraction time QT from the heart rate HR using the regression equation, there is a problem that it is difficult to obtain an accurate regression equation.

FIG. 33 shows a general pulse waveform. By the way, the pulse wave waveform is obtained by measuring the pulsation of the blood flow caused by the contraction and expansion of the heart in the peripheral part, and the waveform shape reflects the movement of the heart. EE in the figure
D (Estimated Ejection Duration) is generally called an ejection period, and is a time during which blood flows from the heart during one heartbeat,
In turn, it corresponds to the systolic time QT.

Therefore, in this embodiment, the approximate ejection time EED (Estimated time) is used instead of the systolic time QT.
Ejection Duration), the approximate ejection time EED
In contrast, the left ventricular pressurization time tsv is set to "EED + 0.1 [se
c] ”to“ EED + 0.2 [sec] ”within the range of“ 0.01
[Sec] ”interval, and at the same time, the systolic blood pressure Emv ′ is changed from“ Eo + Em−20 [mmHg] ”to“ Eo + Em + 20 ”.
[MmHg] ”at intervals of“ 1 mmHg ”.

That is, 451 combinations are assumed for each of the left ventricular pressurization time tsv and the systolic blood pressure Emv '. In each of these combinations, the capacitance Cc is calculated such that the diastolic blood pressure of the calculated pulse wave matches the diastolic blood pressure of the actually measured pulse wave. As a result, since the parameters of the circulatory dynamics can be obtained by using the EED based on the pressure pulse waveform in the peripheral portion of each subject, the apparatus configuration can be simplified, such as the necessity of an electrocardiograph. It is possible to calculate a more accurate circulatory dynamic parameter that reflects.

Next, when the sampling value of the calculated pulse wave in each combination is P1 (t) and the sampling value of the actually measured pulse wave is P2 (t), the waveform average error ε in each combination is obtained by the following equation. Then, the capacitance Cc (aortic compliance) when the waveform average error ε is the smallest is adopted. FIG. 32 shows an example of a flowchart for realizing the process described above. ε = Σt = 0tp (| P2 (t) -P2 (t) |) / (N) (155)

As described above, all the circulatory parameters in which the measured value of the stroke volume and the calculated value match are determined. Here, the values of the circulatory dynamic parameters and the like calculated from the radial artery waveform in the case where a 32-year-old man is a subject are shown below. Capacitance Cc = 0.001213 [cm5 / dyn] Electric resistance Rc = 98.768 [dyn · s / cm5] Inductance L = 15.930 [dyn · s2 / cm5] Capacitance C = 0.0001241 [cm5 / dyn] Electric resistance Rp = 1300.058 [dyn · s / cm5] Left ventricular pressurization time ts = 0.496 [s] One beat time tp = 0.896 [s] Single stroke output SV = 83 0.6 [cc / beat] systolic blood pressure Em '= 117.44 [mmHg] Also, as shown in FIG. 12, it can be seen that the calculated waveform of the radial artery obtained from the calculated parameters and the actually measured waveform match well. .

Data Calculation Process (Step S4) Further, an aortic pressure waveform is obtained based on the values of the circulatory dynamic parameters L, C, Cc, Rc, Rp and the like. That is, by using equation (51) during the systole and using equation (142) during the diastole, the waveform of the voltage v1 is changed for one beat (that is, time 0 to time tp or time t1 to time 1). Only the time (t1 + tp)) is calculated.

Next, the value of the obtained waveform of the origin of the aorta at time t1 is calculated from these equations, and the calculated result is set as the diastolic blood pressure value Eo. Next, the myocardial load index WP is calculated by multiplying the previously determined systolic blood pressure value Em 'by the heart rate HR (= 60 / tp). WP = Em '× HR = Em' × (60 / tp)

Data Output Processing (Step S5) Next, the microcomputer 4 calculates the circulatory dynamic parameters L, C, Cc, Rc, and R obtained by the parameter calculation processing.
p is output to the output device 6 and displayed on the output device. Further, the obtained calculated waveform is output to the output device 6 to display the aortic pressure waveform. Further, the systolic blood pressure value Em 'and the myocardial load index WP are sent to the output device 6 together with the diastolic blood pressure value Eo, and these values are displayed on the output device 6.

[6] Summary of the First Embodiment By the way, in the conventional blood pressure measurement device, the blood pressure is measured on the peripheral side such as the radial artery and the upper arm, and a method of indirectly measuring the burden on the heart. It can be said that there is. However, the change in the burden on the heart is not always reflected in the blood pressure on the peripheral side, and it is not always accurate to see the burden on the heart on the peripheral side.

In view of the above, the first embodiment focuses on the fact that the blood pressure waveform of the central part is particularly important in observing the burden on the heart, and focuses on the aortic root (the central part of the arterial system). The blood pressure waveform is estimated and obtained from the pulse wave waveform measured on the peripheral side. Then, if the systolic blood pressure value, the diastolic blood pressure value, and the myocardial load index WP at the aortic root are calculated from the estimated aortic pressure waveform, these values can be an index directly representing the burden on the heart.

As described above, according to the present embodiment, the systolic blood pressure, the diastolic blood pressure, the myocardial load index, and the aortic pressure waveform on the central side can be shown to the diagnostician and the subject, along with various circulatory parameters.

Since the equation (51) shows the left ventricular pressure waveform itself, the left ventricular pressure waveform may be displayed on the output device 6 instead of the above-described aortic pressure waveform as the central part pressure waveform. good.

Second Embodiment In the first embodiment, the values of the circulatory dynamic parameters are calculated from the radial artery waveform and the stroke volume. However, as described above, in order to detect the stroke volume,
Since the subject needs to wear the cuff band S1, it can be said that the subject is troublesome.

Therefore, in the second embodiment, the blood pressure shape and the like on the central side are estimated by noting the phenomenon that the aortic pressure changes depending on the shape of the radial artery waveform, and representing the waveform shape as a distortion factor. It is. That is, in the present embodiment, the circulatory dynamic parameters are derived based on the distortion rate d obtained from the radial artery waveform.

First, the microcomputer 4 performs a pulse wave reading process and an averaging process in the same manner as in the first embodiment to obtain an average waveform of one radial artery waveform. Next, Fourier analysis of the pulse wave is performed by performing a well-known FFT (fast Fourier transform) process on the average waveform. From the frequency spectrum obtained as a result of the analysis, the amplitude A1 of the fundamental wave, the amplitude A2 of the second harmonic, the amplitude A3 of the third harmonic,..., The amplitude An of the nth harmonic
Ask for. The value of n (n is a natural number) is appropriately determined in consideration of the amplitude of the harmonic. Then, based on these amplitude values, a distortion rate d defined by the following equation is calculated. Distortion d = (A22 + A32 + ... + An2) 1/2 / A1 ... (156)

Next, a circulatory dynamic parameter is estimated from the obtained strain rate d. The estimation is performed based on the finding that there is a considerable correlation between the distortion rate of the radial artery waveform and each value of the circulatory dynamic parameters. That is, the distortion rate d and the circulatory parameters are measured for a large number of subjects in advance, and a relational expression between the distortion rate and each of the circulatory parameters is derived. Here, an example of the correlation between the strain rate d and the measurement results of the circulation dynamic parameters RC, Rp, L, and C is shown in FIGS. In addition,
Although the aortic compliance CC is not shown, a correlation coefficient and a relational expression can be obtained similarly to the other four parameters.

Then, the circulatory dynamic parameters Rc, Rp, L, C, and Cc are calculated based on the distortion factor d calculated by the above equation (156) and the relational equations shown in FIGS. Then, in the same manner as in the output processing of the first embodiment, and from the calculated circulatory dynamic parameters,
A waveform for one beat of the aortic pressure waveform is obtained, and a diastolic blood pressure value Eo, a systolic blood pressure value Em ', and a myocardial load index WP at the aortic root are calculated and displayed on the output device 6.

Third Embodiment In the third embodiment, the systolic blood pressure at the origin of the aorta,
Calculates the work of the heart (hereinafter referred to as cardiac work) from the blood pressure waveform of the aortic root determined in the above manner in addition to the diastolic blood pressure value or the myocardial load index WP and displays the calculated work amount. It is.

This cardiac work is one index indicating the burden on the heart, and is defined by the product of the stroke volume and the aortic pressure.
The cardiac output per minute is converted into the amount of work.
Here, the stroke volume per stroke is defined by the blood flow volume sent out from the heart in one beat, and corresponds to the area of the blood flow waveform coming out of the heart. This stroke volume has a correlation with the systolic area of the aortic pressure waveform, and the stroke volume can be determined by applying the systolic area method to the aortic pressure waveform.

That is, first, the area S of the pulse waveform in the portion corresponding to the systole of the heart is calculated. This will be described with reference to the pulse waveform in FIG. 29. The area of the region from the rising portion of the pulse wave to the depression (notch), that is, the hatched portion in FIG. Next, assuming that a predetermined constant is K, the stroke volume SV can be calculated by the following equation. Stroke volume SV [ml] = area S [mmHg · s] × constant K

On the other hand, the cardiac output is defined by the blood flow sent from the heart in one minute. Therefore, the cardiac output is obtained by converting the stroke volume to one minute. That is, the cardiac output is determined by the product of the stroke volume and the heart rate. In the present embodiment, in the output processing of the first embodiment or the second embodiment, the microcomputer 4
Calculates the amount of cardiac work based on the calculated left ventricular pressure waveform and displays it on the output device 6. Other processes are the same as in the first embodiment or the second embodiment, and a description thereof will be omitted.

Here, the microcomputer 4 calculates the cardiac work Ws by the following procedure. First, ws
Is defined as e · is, this is given by equation (51), equation (90),
It is calculated from equation (91) as follows. ws = e · is = ωsCcEm′2sinωstcosωst + Em′sinωst (D1stcosωst + D2stsinωst) + Em′sinωst (D1trcosω1t ′ + D2trsinω1t ′) exp (−β1157)

Here, the first term and the second term in the equation (157)
Assuming that the term and the third term are w1, w2, and w3, respectively, they are transformed as in the following equations. w1 = (ωsCcEm′2 / 2) sin2ωst (161) w2 = (Em ′ / 2) ｛D1stsin2ωst−D2st (cos2ωst-1)｝ (162) w3 = (Em ′ / 2) [D1tr ｛sin (ωst + ω1t) ') + Sin (ωst-ω1t')｝-D2tr ｛cos (ωst + ω1t ')-cos (ωst-ω1t')｝] exp (-β1t ') (163)

Next, from equation (82), ωst + ω1t ′ = ωst + ω1 (t−t1) = (ωs + ω1) t−ω1t1 = ωat−Φ (164), and ωst−ω1t ′ = (ωs−ω1) t + ω1t1 = ωbt + Φ (165)

That is, ωa = ωs + ω1 (166) ωb = ωs−ω1 (167) Φ = ω1t1 (168)

Then, equation (163) becomes the following equation. w3 = (Em '/ 2) [D1tr {sin (ωat-Φ) + sin (ωbt + Φ)} -D2tr ｛cos (ωat-Φ) -cos (ωbt + Φ)｝] exp (-β1t') (169)

Next, W1, W2, and W3 are defined as follows, and the following equations are derived from equations (161), (162), and (169). W1 = ∫w1dt = − (CcEm′2 / 4) cos2ωst = (CcEm′2 / 4) (1-2 cos2ωst) (173) W2 = ∫w2dt = (Em ′ / 2) [− ｛D1st / (2ωs) {Cos2ωst-D2st {sin2ωst / (2ωs) −t}] = {Em ′ / (4ωs)} (D1st + 2D2stωst) −2cosωst (D1stcosωst + D2stsinωst)} (174) W3 = {E3m2} (−ωaD1tr + β1D2tr) cos (ωat−Φ) − (β1D1tr + ωaD2tr) sin (ωat−Φ)｝ / (β12 + ωa2) + ｛− (ωbD1tr + β1D2tr) cos (ωbt + Φ) + (− β1D1tr + ωb｝ 2t) + (− β1D1tr + ωbω2t) exp (-β1t ') ... (175)

Since the work amount Ws is obtained by converting the sum of the above W1, W2 and W3 into "minutes", it is finally expressed by the following equation. Ws = (W1 + W2 + W3) .times.10 @ -7.times.60 / tp [J / min] (176) In addition to the systolic blood pressure value, the diastolic blood pressure value and the myocardial load index WP at the aortic root, the heart work described above. The meaning of displaying the quantity is as follows.

By calculating the above-mentioned cardiac work based on the aortic pressure waveform, the systolic blood pressure value, the minimum blood value, or the myocardial load index WP at the origin of the aorta is determined as an index representing the burden on the heart. It is also possible to provide useful indicators.
Here, the significance of calculating the amount of cardiac work will be described with reference to examples below.

Now, consider a case in which a hypertensive is treated by administering a hypotensive agent to a patient. Normally, if the drug is effective, the systolic blood pressure value and the diastolic blood pressure value measured in the radial artery change, and the effect of the drug can be confirmed. However, even when the systolic blood pressure value and the diastolic blood pressure value do not change, the medicine is actually effective, and the load on the heart itself may be reduced. This is because the role of the antihypertensive agent is to reduce the load on the heart somewhere in the arterial system, and the blood pressure in the radial artery does not necessarily need to be reduced.

As described above, even when there is no remarkable change in the blood pressure value in the peripheral portion of the arterial system such as the radial artery, the cardiac work calculated from the blood pressure waveform at the aortic root is calculated. This makes it possible to know the true burden of the heart. By the way, such changes in the burden on the heart
Although it can be found by closely examining the blood pressure waveform at the aortic root, the calculation of the cardiac work makes it possible to quantitatively express subtle changes in the waveform.

Therefore, by obtaining and displaying not only the systolic blood pressure value and the diastolic blood pressure value but also the myocardial stress index WP and the cardiac work, the evaluation of antihypertensive therapy can be performed more precisely. . FIGS. 22 to 24 show the results of calculating the cardiac work for each of the above-described first to third types of pulse wave shapes.

Fourth Embodiment In the first to third embodiments described above, the myocardial load index WP is always calculated based on the aortic root blood pressure and the detected heart rate. In the heart rate range where the difference between the peripheral blood pressure and the aortic root blood pressure can be ignored, the form uses the peripheral blood pressure instead of the aortic root blood pressure, and the peripheral blood pressure and the aortic root blood pressure This is an embodiment for reducing the arithmetic processing as a whole by using the aortic root blood pressure in a heart rate range where the difference cannot be ignored.

It is generally known that as the heart rate increases, the difference between the aortic root blood pressure and the peripheral blood pressure increases. Therefore, in the fourth embodiment, when the fluctuation range of the heart rate is within the predetermined reference heart rate fluctuation range, the myocardial load index WP is obtained using the peripheral blood pressure (systolic blood pressure) and the detected heart rate. When the fluctuation range of the heart rate becomes equal to or larger than the reference heart rate fluctuation range, the myocardial load index is determined using the aortic root blood pressure (systolic blood pressure) and the detected heart rate.

More specifically, the variation in the heart rate at rest with respect to the reference heart rate, which is the human heart rate (of course, having individual differences) is about ± 10 [%]. Therefore, for example, if the actual heart rate fluctuation is less than ± 10% relative to the reference heart rate at rest, it is possible to ignore the difference between the peripheral blood pressure and the aortic root blood pressure. Then, the myocardial load index WP is calculated by the following equation based on the peripheral blood pressure Pperi and the heart rate HR. WP = Pperi × HR On the other hand, if the actual heart rate variance is ± 15 [%] or more with respect to the reference heart rate at rest taking into account the measurement error margin, the peripheral blood pressure and the aortic root It is determined that the difference from the blood pressure cannot be ignored, and the myocardial load index WP is calculated by the following equation based on the aortic root blood pressure Pcent and the heart rate HR. WP = Pcent × HR According to the fourth embodiment, if the actual heart rate fluctuation is less than a predetermined range with respect to the reference heart rate at rest,
Since the myocardial load index WP is calculated using the peripheral blood pressure, the processing is simplified and the processing speed is improved as compared with the case where the myocardial load index is calculated always using the aortic root blood pressure. It becomes possible.

If the actual heart rate fluctuation is equal to or more than a predetermined range with respect to the reference heart rate at rest, the myocardial load index WP is calculated using the aortic root blood pressure calculated based on the circulatory parameters. As a result, it becomes possible to calculate a more accurate myocardial load index as compared with the case where the myocardial load index WP is calculated using the peripheral blood pressure. As described above, according to the fourth embodiment, it is possible to always calculate an accurate myocardial load index WP, although the processing can be simplified as a whole.

Fifth Embodiment In the first to third embodiments, the myocardial load index WP is always calculated at a predetermined timing based on the aortic root blood pressure and the detected heart rate. On the other hand, when it is not considered that the aortic root blood pressure has changed much, it is considered that it is not always necessary to continuously calculate the myocardial load index WP.

Therefore, in the fifth embodiment, the myocardial load index WP is newly calculated only when it is considered that the aortic root blood pressure has significantly changed, and it is considered that the aortic root blood pressure has changed much. When there is no myocardial load index WP, this embodiment is an embodiment for holding and displaying the myocardial load index WP obtained last time without calculating the myocardial load index WP, thereby reducing the amount of calculation processing.

By the way, in order to calculate the aortic root blood pressure, it is necessary to calculate the circulatory dynamic parameters prior to the calculation. In this case, if the change (rate of change) of the currently obtained hemodynamic parameters with respect to the previously obtained (or a plurality of previous times) hemodynamic parameters is small, the aortic root that will be obtained by the currently obtained hemodynamic parameters will be obtained. It is also considered that the change (rate of change) of the aortic root blood pressure to the aortic root blood pressure, which may be obtained by the previously obtained circulatory dynamic parameters, is small.

Therefore, in the fifth embodiment, the circulatory dynamic parameter obtained this time is compared with the circulatory dynamic parameter obtained last time, and when the change rate of each circulatory dynamic parameter is smaller than a predetermined reference change rate. Holds the myocardial load index obtained last time (or a plurality of times before) without calculating the aortic root blood pressure and, consequently, the myocardial load index WP, and continues the display.

The circulatory dynamic parameters obtained this time are compared with the circulatory dynamic parameters obtained last time. If the change rate of each circulatory dynamic parameter is equal to or greater than a predetermined reference change rate, the circulatory dynamic parameter obtained this time is compared. Is used to calculate the aortic root blood pressure and the myocardial load index WP.

More specifically, the circulatory parameters obtained this time are compared with the circulatory parameters obtained last time (or a plurality of times before), and the change rate of each circulatory parameter is ± 5% or more. In this case, the calculation of the aortic root blood pressure and the calculation of the myocardial load index WP based on the calculated aortic root blood pressure are performed.

On the other hand, the rate of change of each circulatory dynamic parameter is ±
If it is less than 5%, the calculation of the aortic root blood pressure and the calculation of the myocardial load index WP are not performed, the myocardial load index obtained last time (or a plurality of times before) is retained, and the display is continued. As a result, according to the fifth embodiment, unnecessary calculations need not be performed, the amount of calculation processing can be reduced, the processing can be simplified, and the overall processing speed can be improved.

Modification of Embodiment The present invention is not limited to the above-described embodiment,
For example, various modifications are possible as follows. For example,
A form in which a circulatory dynamic parameter is obtained without measuring the stroke volume SV is also conceivable. That is, according to this embodiment, the inductance L among the circulatory parameters is set to a fixed value, and the values of the other circulatory parameters are calculated based only on the waveform of the radial artery pulse wave measured from the subject. To do it. In this way, the stroke volume measuring device 2 required in the configuration of FIG. 1 can be omitted as shown in FIG. Therefore, the mode of measurement in this embodiment is shown in FIG.
As shown in FIG. 2, the cuff band S1 required in FIG. 2 is unnecessary.

When the value of the inductance L is fixed as described above, the accuracy of the obtained circulatory dynamic parameters is reduced as compared with the method using the actually measured stroke volume. Therefore, to compensate for this, as shown in FIG.
The radial artery waveform (measured waveform) W1 obtained by the measurement and the radial artery waveform (calculated waveform) W2 obtained by the calculation are superimposed and displayed on the output device 6. Then, first, the value of the inductance L is set to the above-mentioned fixed value to obtain a calculated waveform W2, and this waveform is displayed on the output device 6 to display the measured waveform W1.
And the degree of coincidence of the waveforms. Next, the diagnostician determines an appropriate value different from the fixed value as the inductance L, obtains the calculated waveform W2 again, and checks the degree of coincidence with the measured waveform W1 on the output device 6. Thereafter, the diagnostician appropriately determines some values of the inductance L in the same manner as described above, obtains a calculated waveform W2 for each value of the inductance L, and outputs each of the calculated waveforms W2 and the measured waveform on the output device 6. Compare with W1. Then, one of the calculated waveforms W2 that best matches the measured waveform W1 is selected, and the value of the inductance L at that time is determined as the optimum value.

As a model of the pressure waveform at the aortic root, a trapezoidal wave may be used instead of the above-described triangular wave. In this case, since the waveform becomes closer to the actual pressure waveform than in the case where the waveform is approximated by a triangular wave, a more accurate circulatory dynamic parameter can be calculated.

The measurement positions of the pulse wave and the stroke volume are not limited to those shown in FIGS. 2 and 16, but may be any parts of the body of the subject. That is, in the above-described embodiment, the measurement mode is such that the cuff band S1 is attached to the upper arm of the subject. However, considering the convenience of the subject, it is preferable that the cuff band is not used.

As an example, a form in which both the radial artery waveform and the stroke volume are measured at the wrist can be considered. As an example of this type of configuration, as shown in FIG. 18, a sensor 12 composed of a sensor for measuring blood pressure and a sensor for measuring stroke volume is mounted on a belt 13 of a wristwatch 11, and a pulse wave analyzer is provided. Component 10 other than the sensor 12
Is built in the main body of the wristwatch 11. Then, as shown in the figure, the sensor 12 is slidably attached to the belt 13 by the attachment 14, and when the subject puts the wristwatch 11 on the wrist, the sensor 12 is pushed to the radial artery with an appropriate pressure. Is to be applied.

Further, a form in which a pulse wave and a stroke volume are measured with a finger is also conceivable. FIG. 19 shows a configuration example of an apparatus according to this form. As shown in the figure, a sensor 22 composed of a sensor for measuring blood pressure and a sensor for measuring stroke volume is attached to the base of a finger (in this example, the index finger). Components 10 other than the lead wire 2
It is connected to the sensor 22 via 3 and 23.

Furthermore, by combining these two measurement modes, a stroke volume is measured once at the wrist, a pulse wave is measured at the finger, and a pulse wave is measured at the finger.
It is possible to realize a form of measuring the stroke volume and measuring the radial artery wave at the wrist.

[0200] By adopting a configuration without the cuff band as described above, the subject does not have to roll his arm, and the burden on the subject in measurement is reduced. On the other hand, a configuration shown in FIG. 20 can be considered as a mode using only the cuff band. As shown in the figure, a sensor 32 composed of a sensor for measuring blood pressure and a sensor for measuring stroke volume, and a component 10 of the pulse wave analyzer other than the sensor 32 are connected to the upper arm of the subject by a cuff band. It can be seen that the configuration is simpler than that of FIG.

In the above embodiment, the pulse wave is used to calculate the circulatory dynamic parameters. However, the present invention is not limited to this, and it is possible to use other biological conditions. Needless to say. In the above embodiments, the myocardial load index is calculated based on the aortic root blood pressure based on the calculated circulatory dynamic parameters and the detected heart rate. However, the peripheral blood pressure of the living body or the pulse of the peripheral blood of the living body is calculated. Based on the wave shape,
If the estimated value of the aortic root blood pressure of the living body is calculated, the myocardial load index can be similarly calculated based on the estimated value of the aortic root blood pressure and the detected heart rate regardless of the calculation method. It is.

For example, instead of the aortic root blood pressure calculated on the basis of the circulatory dynamic parameters, the living body is determined based on a predetermined transfer function such as a GTF (general transfer function) based on the pulse wave waveform of the peripheral part of the living body. It is also possible to calculate the estimated value of the blood pressure at the aortic root in the aorta, and calculate the myocardial load index based on the calculated estimated value of the blood pressure at the aortic root and the detected heart rate. In this case, the predetermined transfer function is not limited to a general transfer function applicable to all persons, and may be a transfer function obtained by adding a correction unique to a specific living body.

[0203] According to the present embodiment of the embodiment, since the calculated cardiac load index based on the estimated value and the heart rate detected in the aortic root pressure based on the calculated circulatory state parameters, using peripheral portion BP It is possible to calculate the optimal myocardial load index under a wider range of conditions than when calculating the myocardial load index by using the above method.

When the rate of change in heart rate is equal to or higher than the reference rate, the myocardial load index is calculated based on the blood pressure at the aortic root and the detected heart rate. As compared with the configuration in which the myocardial load index is calculated based on the calculated heart rate, the processing can be further simplified and the processing can be speeded up.

Further, according to the configuration in which the myocardial load index is calculated based on the peripheral blood pressure and the detected heart rate when the rate of change of the heart rate is less than the reference rate of heart rate change, an accurate myocardial load index can be obtained. Nevertheless, the processing can be simplified. Furthermore, when the variation rate of the calculated circulatory parameters with respect to the reference circulatory parameters is equal to or more than a preset parameter reference variation rate, the myocardial load index is calculated based on the aortic root blood pressure and the detected heart rate. According to this, in the state where the myocardial load index does not change much, there is no unnecessary calculation processing,
Processing can be simplified.

Further, according to the configuration in which the myocardial load index is calculated based on the peripheral blood pressure and the detected heart rate when the rate of change of the circulatory dynamic parameter is less than the reference parameter change rate, an accurate myocardial load index can be obtained. Nevertheless, the processing can be simplified. Furthermore, based on the peripheral blood pressure of the living body or the pulse wave waveform of the peripheral part of the living body, the estimated value of the aortic root blood pressure of the living body is calculated, the heart rate of the living body is detected, and the estimated value of the aortic root blood pressure and According to the configuration for calculating the myocardial load index based on the detected heart rate, simple,
It is possible to calculate the myocardial load index accurately and quickly.

Further, an estimated value of the blood pressure of the aortic root of the living body is calculated based on the pulse wave waveform of the peripheral part of the living body and a predetermined transfer function, the heart rate of the living body is detected, and the blood pressure of the aortic root of the living body is calculated. According to the configuration for calculating the myocardial load index based on the detected heart rate, the myocardial load index can be calculated simply, accurately, and quickly.

[0208]

According to the present invention, in calculating the circulatory parameters, the left ventricular pressurization time calculated using the above-described approximate ejection period as an initial value eliminates the need for an electrocardiograph. Can be calculated and more accurate hemodynamic parameters reflecting the circulatory dynamics of the subject can be calculated, so that the estimated value of the aortic root blood pressure in the living body can be calculated more accurately based on the obtained circulatory dynamic parameters. can do.

Also, an estimated value of the aortic root blood pressure of the living body is calculated based on the peripheral blood pressure of the living body or the pulse wave waveform of the peripheral part of the living body, the heart rate of the living body is detected, and the blood pressure of the aortic root is calculated. Since the myocardial load index is calculated based on the estimated value and the detected heart rate, the myocardial load index can be calculated simply, accurately, and quickly.

Further, an estimated value of the aortic root blood pressure of the living body is calculated based on the pulse wave waveform of the peripheral part of the living body and a predetermined transfer function, the heart rate of the living body is detected, and the aortic root blood pressure and the detected blood pressure are detected. Since the myocardial load index is calculated based on the determined heart rate, the myocardial load index can be calculated simply, accurately, and quickly.

Further, the myocardial load index is calculated based on the aortic root blood pressure based on the calculated circulatory dynamic parameters and the heart rate detected separately from an electrocardiogram or the like, or the heart rate detected from a pulse wave waveform. It is possible to calculate an optimal myocardial load index under a wider range of conditions than when calculating a myocardial load index by using.

Further, the myocardial load index calculating means calculates the myocardial load index based on the aortic root blood pressure and the detected heart rate when the rate of change of the heart rate is equal to or higher than the reference rate of heart rate change. Compared with the configuration in which the myocardial load index is calculated based on the origin blood pressure and the detected heart rate, the processing can be further simplified and the processing can be speeded up.

Furthermore, the myocardial load index calculating means calculates the myocardial load index based on the peripheral blood pressure and the detected heart rate when the rate of change of the heart rate is less than the reference rate of change of the heart rate. Despite getting the load index,
Processing can be simplified.

The myocardial load index calculating means calculates the myocardial load index based on the aortic root blood pressure and the detected heart rate when the fluctuation rate of the calculated circulatory parameter with respect to the reference circulatory parameter is equal to or greater than a preset parameter reference fluctuation rate. Since the myocardial load index is calculated, in a state where the myocardial load index does not change much, the calculation processing is not performed unnecessarily, so that the processing can be simplified.

Further, the myocardial load index calculating means calculates the myocardial load index based on the peripheral blood pressure and the detected heart rate when the change rate of the circulatory dynamic parameter is less than the reference parameter change rate. Despite being able to obtain, the processing can be simplified.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a pulse wave analyzer according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a measurement mode using a pulse wave detection device and a stroke volume meter in the first embodiment.

FIG. 3A is a circuit diagram showing a four-element lumped parameter model of a human artery system, and FIG. 3B is a circuit diagram showing a five-element lumped parameter model.

FIG. 4 is a diagram showing a left ventricular pressure waveform and a blood pressure waveform at an aortic root.

FIG. 5 is a diagram showing a waveform obtained by modeling a blood pressure waveform at an aortic root.

FIG. 6 is a flowchart illustrating an outline of an operation of the pulse wave analyzer according to the first embodiment.

FIG. 7 is a flowchart illustrating an operation of a parameter calculation process of the pulse wave analyzer according to the first embodiment.

FIG. 8 is a flowchart illustrating an operation of a parameter calculation process of the pulse wave analyzer according to the first embodiment.

FIG. 9 shows α, ω of the pulse wave analyzer according to the first embodiment.
It is a flowchart which shows operation | movement of a calculation process.

FIG. 10 is a flowchart illustrating an operation of a ω calculation process of the pulse wave analyzer according to the first embodiment.

FIG. 11 is a waveform diagram illustrating a radial artery waveform obtained by the averaging process of the pulse wave analyzer according to the first embodiment.

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

FIG. 13 is a diagram illustrating the contents of normalization processing applied to the radial artery waveform obtained by the averaging processing of the pulse wave analyzer according to the first embodiment.

FIG. 14 is a diagram showing a correlation between a left ventricular pressurization time ts and a time tp of one beat.

FIG. 15 is a block diagram illustrating a configuration of a pulse wave analyzer according to a second embodiment.

FIG. 16 is a diagram illustrating a measurement mode using the pulse wave detection device according to the second embodiment.

FIG. 17 is a diagram showing an overlap display of a measured waveform of a radial artery wave and a calculated waveform displayed on the output device in the second embodiment.

FIG. 18 is a perspective view of a form in which components of the pulse wave analyzer except for a sensor are incorporated in a wristwatch, and the sensor is attached to a band of the wristwatch.

FIG. 19 is a perspective view of a form in which components of the pulse wave analyzer except for a sensor are incorporated in a wristwatch, and the sensor is attached to a base of a finger.

FIG. 20 is a configuration diagram of a configuration in which components of the pulse wave analyzer except for the sensor and the sensor are attached to the upper arm by a cuff band.

FIG. 21 is a block diagram illustrating a configuration of a blood pressure measurement device according to a third embodiment of the present invention.

FIG. 22 is a diagram illustrating a relationship between an aortic pressure waveform (dotted line) and a radial artery waveform (solid line) in a first type of pulse wave.

FIG. 23 is a diagram showing a relationship between an aortic pressure waveform (dotted line) and a radial artery waveform (solid line) in a second type of pulse wave.

FIG. 24 is a diagram illustrating a relationship between an aortic pressure waveform (dotted line) and a radial artery waveform (solid line) in a third type of pulse wave.

FIG. 25 is a diagram showing the relationship between central vascular resistance Rc and strain rate d.

FIG. 26 is a diagram showing the relationship between peripheral vascular resistance Rp and strain rate d.

FIG. 27 is a diagram showing a relationship between inertia L and distortion rate d due to blood flow.

FIG. 28 is a diagram illustrating a relationship between compliance C and distortion factor d.

FIG. 29 illustrates the systolic area method.

FIG. 30 is a diagram showing a configuration of a blood pressure measurement device according to a conventional technique.

FIG. 31 is a flowchart of a program for obtaining a capacitance Cc.

FIG. 32 is a flowchart of another program for obtaining the capacitance Cc.

FIG. 33 is an explanatory diagram of a pulse waveform.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 pulse wave detection device 2 1 stroke volume measuring device 3 A / D converter 4 microcomputer 5 keyboard 6 output device 7 monitor 61 measured blood pressure display unit 62 estimated blood pressure display unit in central part 63 warning display unit 64 parameter display unit 65 Printer 66 Print command button 67 CRT display 68 Myocardial load index display

Claims (24)

[Claims] 1. A measuring means for measuring a state of the living body including an approximate ejection period based on a pulse wave waveform of a peripheral part of the living body, and a central part to a peripheral part of the living body based on the state of the living body. Analysis means for calculating circulatory parameters including viscoelasticity of the aorta as circulatory parameters representing the circulatory dynamics of the arterial system leading to, and calculating an estimated value of the aortic origin blood pressure of the living body based on the circulatory dynamic parameters Aortic blood pressure calculation means, wherein the analysis means uses a left ventricular pressurization time calculated using the approximate ejection period as an initial value when calculating the circulatory dynamic parameters. apparatus. 2. Aortic blood pressure calculating means for calculating an estimated value of the aortic root blood pressure of the living body based on the peripheral blood pressure of the living body or the pulse wave waveform of the peripheral part of the living body; A biological state measurement comprising: a heart rate detecting means for detecting; and a myocardial load index calculating means for calculating a myocardial load index based on the estimated value of the aortic root blood pressure and the detected heart rate. apparatus. 3. Aortic blood pressure calculating means for calculating an estimated value of the aortic origin blood pressure of the living body based on a predetermined transfer function from a pulse wave waveform of a peripheral part of the living body, and a heart rate detecting the heart rate of the living body. A biological condition measuring device comprising: a number detecting means; and a myocardial load index calculating means for calculating a myocardial load index based on the estimated value of the aortic root blood pressure and the detected heart rate. 4. The biological condition measuring device according to claim 1, wherein a heart rate detecting means for detecting a heart rate of the living body, and a myocardial load based on the estimated value of the aortic root blood pressure and the detected heart rate. A biological condition measuring device, comprising: a myocardial load index calculating means for calculating an index. 5. The biological condition measuring device according to claim 1, wherein a heart rate detecting means for detecting a heart rate of the living body based on the pulse wave waveform, an estimated value of the aortic root blood pressure and the detected blood pressure. And a myocardial load index calculating means for calculating a myocardial load index based on the heart rate. 6. A measuring means for measuring a state of the living body based on a pulse wave waveform of a peripheral part of the living body, and an arterial circulation from a central part to a peripheral part of the living body based on the state of the living body. As the circulatory parameters representing the kinetics, analysis means for calculating circulatory parameters including viscoelasticity of the aorta and aortic blood pressure calculating means for calculating an estimated value of the aortic root pressure of the living body based on the circulatory parameters, Heart rate detecting means for detecting the heart rate of the living body, and myocardial load index calculating means for calculating a myocardial load index based on the estimated value of the aortic root blood pressure and the detected heart rate. Characteristic biological condition measuring device. 7. The biological condition measuring apparatus according to claim 1, wherein the circulatory dynamic parameters are vascular resistance due to blood viscosity at the central part, inertia of blood, Vascular resistance in the periphery,
A biological condition measuring device, comprising: viscoelasticity of blood vessels in the peripheral part. 8. The biological condition measuring apparatus according to claim 1, wherein the aortic blood pressure calculating means includes a diode corresponding to an aortic valve, and a blood viscosity at the central portion. Resistance corresponding to vascular resistance, inductance corresponding to inertia of blood, first capacitance corresponding to viscoelasticity of the aorta, and second resistance corresponding to vascular resistance at the peripheral portion. Resistance and
A model having a second capacitance corresponding to the viscoelasticity of a blood vessel in the peripheral portion, wherein a series circuit of the diode and the first capacitance is connected between a pair of input terminals, A parallel circuit including the second capacitance and the second resistor is inserted between output terminals, and the first resistor and the second resistor are provided between both terminals of the first capacitance and the output terminal. The circulatory dynamics of the arterial system are modeled by a five-element lumped-parameter model in which a series circuit composed of the inductance is inserted to determine the circulatory dynamics parameter, and the voltage between both terminals of the first capacitance is determined. A biological condition measuring device, wherein the waveform is the aortic pressure waveform. 9. The biological condition measuring device according to claim 1, wherein the biological condition is a pulse wave in a peripheral part of the arterial system, and the blood pressure calculating means includes: The five-element lumped constant model is such that, when an electric signal corresponding to the left ventricular pressure of the living body is given between the input terminals, an electric signal corresponding to the pulse wave waveform is obtained from the output terminal. A biological condition measuring apparatus characterized in that the value of each element constituting (i) is determined. 10. The biological condition measuring apparatus according to claim 1, wherein the biological condition is a pulse wave in a peripheral portion of the arterial system, and the waveform of the pulse wave. From the blood pressure calculating means to determine the circulatory parameters based on the correlation between the circulatory parameters and the pulse wave strain. Biological condition measuring device. 11. The method according to claim 1, wherein the control information is stored in the storage device.
The biological condition measuring device according to any one of claims 1 to 3, further comprising a stroke volume detection unit configured to detect a stroke volume of the living body, wherein the blood pressure calculation unit calculates a stroke volume obtained from the aortic pressure waveform.
The value of the circulatory dynamics parameter is adjusted so that the calculated value of stroke volume matches the actual measured value of stroke volume measured by the stroke volume measuring means. Biological condition measuring device. 12. The method as claimed in claim 1, wherein said first to fourth steps are performed in accordance with a second embodiment.
The biological condition measuring device according to any one of claims 1 to 3, further comprising a work amount calculating unit configured to calculate a work amount of the heart of the living body based on the aortic pressure waveform. 13. The method according to claim 1, wherein the control information is stored in the storage device.
In the biological condition measuring device according to any one of the above, the determining means for determining whether or not the rate of change of the detected heart rate with respect to the reference heart rate, which is the heart rate at rest, exceeds a preset reference heart rate rate of change. The myocardial load index calculating means, when the fluctuation rate is equal to or higher than the reference heart rate fluctuation rate based on the discrimination, based on the aortic root blood pressure and the detected heart rate. The biological condition measuring device characterized by calculating: 14. The biological condition measuring device according to claim 13, wherein the peripheral blood pressure detecting means for non-invasively detecting the peripheral blood pressure of the living body, and the myocardial load index calculating means, based on the determination. The biological condition measuring device, wherein when the variability is less than the reference heart rate variability, a myocardial load index is calculated based on the peripheral blood pressure and the detected heart rate. 15. The method according to claim 1, wherein the control unit comprises:
In the biological condition measuring device according to any one of the above, the myocardial load index calculating means, the predetermined reference of the calculated circulatory dynamic parameters at a predetermined timing relative to a reference circulatory dynamic parameter is a parameter reference. A biological condition measuring device which calculates a myocardial load index based on the aortic root blood pressure and the detected heart rate when the fluctuation rate is equal to or higher than the fluctuation rate. 16. The biological condition measuring device according to claim 15, further comprising a peripheral blood pressure detecting unit that non-invasively detects a peripheral blood pressure of the living body, wherein the myocardial load index calculating unit performs the determination. A biological condition measuring apparatus, wherein a myocardial load index is calculated based on the peripheral blood pressure and the detected heart rate when the fluctuation rate is smaller than the reference parameter fluctuation rate. 17. A measurement process for measuring a state of the living body including a general ejection period based on a pulse waveform of a peripheral part of the living body, and a central part to a peripheral part of the living body based on the state of the living body. An analysis process of calculating circulatory parameters including viscoelasticity of the aorta as circulatory parameters representing the circulatory dynamics of the arterial system up to, and calculating an estimated value of the aortic root blood pressure of the living body based on the circulatory parameters An aortic blood pressure calculation process, wherein the analysis process uses the left ventricular pressurization time calculated using the approximate ejection period as an initial value when calculating the circulatory dynamic parameters. Method. 18. A measurement process for measuring a state of the living body based on a pulse wave waveform of a peripheral part of the living body, and a circulation of an arterial system from a central part to a peripheral part of the living body based on the state of the living body. As a circulatory parameter representing the kinetics, an aortic blood pressure calculation process of calculating an estimated value of the aortic root blood pressure of the living body based on the analysis process of calculating a circulatory parameter including viscoelasticity of the aorta and the circulatory parameter, A heart rate detection process of detecting the heart rate of the living body; and a myocardial load index calculation process of calculating a myocardial load index based on the aortic root blood pressure and the detected heart rate. Biological condition measurement method. 19. The living body condition measuring method according to claim 18, wherein a fluctuation rate of the detected heart rate with respect to a reference heart rate, which is a heart rate at rest, exceeds a preset reference heart rate fluctuation rate. The myocardial load index calculation process, wherein the myocardial load index calculation process, when the fluctuation rate is equal to or more than the reference heart rate fluctuation rate based on the discrimination, the aortic root blood pressure and the detected heart rate A method for measuring a biological condition, comprising calculating a myocardial load index based on the biological condition. 20. The living body condition measuring method according to claim 19, further comprising a peripheral blood pressure detecting process for non-invasively detecting a peripheral blood pressure of the living body, wherein the myocardial load index calculating process includes: And calculating a myocardial load index based on the peripheral blood pressure and the detected heart rate when the fluctuation rate is less than the reference heart rate fluctuation rate. 21. The biological condition measuring method according to claim 17, wherein a heart rate detection process for detecting a heart rate of the living body, and a myocardial load based on the estimated value of the aortic root blood pressure and the detected heart rate. A myocardial load index calculating process for calculating an index; 22. The biological condition measuring method according to claim 17, wherein a heart rate detecting process for detecting a heart rate of the living body based on the pulse wave waveform, an estimated value of the aortic root blood pressure, and the detected A myocardial load index calculating process for calculating a myocardial load index based on the heart rate. 23. The biological condition measuring method according to claim 17, wherein the myocardial load index calculation process is a criterion that is the circulatory dynamic parameter at a predetermined timing of the calculated circulatory dynamic parameter. A biological condition measuring method comprising: calculating a myocardial load index based on the aortic root blood pressure and the detected heart rate when the variation rate of the hemodynamic parameters is equal to or greater than a preset parameter reference variation rate. . 24. The biological condition measuring method according to claim 23, further comprising a peripheral blood pressure detecting process for non-invasively detecting a peripheral blood pressure of the living body, wherein the myocardial load index calculating process includes: And calculating a myocardial load index based on the peripheral blood pressure and the detected heart rate when the fluctuation rate is less than the reference parameter fluctuation rate.