JP2003245256A - Dicrotic notch detector and pulsation propagation speed information detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dicrotic notch detector which can detect the timing of the generation of dicrotic notches even when the dicrotic notches are not clearly recognizable in pulsation. <P>SOLUTION: Locations in the generation of the dicrotic notches contained in the pulsation are determined by a location of generation decision means 66 based on the mean P<SB>av</SB>of waveforms calculated by a mean calculation means 64 and even when the dicrotic notches DN are not clearly recognizable in the pulsation, the timing of the generation of the dicrotic notches DN can be detected accurately. In other words, physiologically, this utilizes the fact that the terminal sytolic pressure can be approximated by the average blood pressure of the artery involved and the portion equivalent to the average blood pressure in the pulsation is defined as the timings of the generation of the dicrotic notches DN. Thus, even if the timings of the generation of dicrotic notches DN corresponding to the closure timing of the aortic valve may not be clearly recognized in the shape of the pulsation, the timings can be determined. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dichroic notch detection device for detecting a dichroic notch generation location of a pulse wave generated from an artery of a living body, and a pulse wave propagation velocity information detection device using the dichroic notch detection device.

[0002]

2. Description of the Related Art A pulse wave generated from an artery of a living body includes small nicks or small waveforms called dichroic notches associated with closure of an aortic valve. Such dichroic notch is used for PEP (Pre Eject
It is used as a reference point for measurement of ion period) and blood ejection time ET (Ejection Time), and is also used as a reference point for measurement of a time difference for calculating a pulse wave velocity between two parts of a living body.

[0003]

By the way, depending on the pulse wave detection part of the living body and the pulse wave detection method, it is unavoidable that the detected pulse wave is rounded or distorted and is included in the pulse wave. Since the dichroic notch may not be clearly recognized, the above-mentioned precursor time PEP and ejection time E
There is a possibility that T, pulse wave velocity, etc. cannot be measured accurately, and sufficient diagnostic accuracy cannot be obtained. For example, from the rising point of the pulse wave obtained from the artery to the generation point of the dichroic notch is measured as the blood ejection time ET, and the dichroic notch is generated from the S wave of the electrocardiographically induced waveform or the 1st sound of the heart sound. Precursor time PEP by subtracting the ejection time ET from the time to the point
Is measured, the ejection time ET and the precursor time PE if the dichroic notch cannot be clearly recognized.
The accuracy of P cannot be obtained. Also, when the pulse wave velocity is determined from the time difference between the dichroic notches generated in the pulse waves detected from two parts of the living body and the distance between the detected parts, if the dichroic notches cannot be clearly recognized, , The accuracy of the pulse wave velocity cannot be obtained.

The present invention has been made in view of the above circumstances. A first object of the present invention is to accurately determine the timing of occurrence of a dichroic notch even when the dichroic notch cannot be clearly recognized in a pulse wave. It is to provide a dichroic notch detection device that can detect the above. A second object of the present invention is to provide a pulse wave velocity information detecting device which can obtain the accuracy of the pulse wave velocity even when the dichroic notch cannot be clearly recognized in the pulse wave.

[0005]

[Means for Solving the Problem] The gist of the first invention for achieving the first object is to include the pulse wave generated from an artery of a living body and to correspond to the closure of the aortic valve. A dichroic notch detection device for detecting a dichroic notch that is a waveform, (a) an average value calculation means for calculating the average value of the waveform of a predetermined section in the pulse wave, (b) the average value calculation An occurrence location determination means for determining the occurrence location of the dichroic notch contained in the pulse wave based on the average value of the waveform calculated by the means,
To include.

[0006]

With the above arrangement, the occurrence location determining means determines the occurrence location of the dichroic notch contained in the pulse wave based on the average value of the waveform calculated by the average value calculating means. Even when the dichroic notch cannot be clearly recognized in the pulse wave, the time when the dichroic notch occurs can be accurately detected. That is, physiologically, the fact that the end-systolic blood pressure in an artery can be approximated by the mean blood pressure in that artery is used,
By setting the part of the pulse wave that corresponds to the mean blood pressure value as the dichroic notch occurrence time, it is not possible to clearly recognize the dichroic notch occurrence time corresponding to the aortic valve closing time in the pulse wave shape. Is also determined.

Here, the average value calculating means calculates the average value P _av of the pulse wave by dividing the integrated value of the pulse wave in a predetermined section of the pulse wave by the length of the section.
The timing of occurrence of the dichroic notch DN is accurately determined.

[0008]

[Second Means for Solving the Problem] The gist of the second invention for achieving the second object is to provide a first cuff and a second cuff wound around two parts of a living body. A first cuff pulse wave detection device and a second cuff pulse wave detection device that detect a first cuff pulse wave and a second cuff pulse wave that are pressure oscillations generated in the first cuff and the second cuff, respectively. The pulse wave based on the time difference between the reference point of the first cuff pulse wave detected by the first cuff pulse wave detection device and the reference point of the second cuff pulse wave detected by the second cuff pulse wave detection device A pulse wave propagation velocity information detecting apparatus for detecting propagation velocity information, comprising: (a) an average value calculating means for calculating an average value of waveforms of a predetermined section in the first cuff pulse wave and / or the second cuff pulse wave. , (B) Based on the average value of the waveform calculated by the average value calculation means, A reference point generator location determination means for determining a first cuff pulse wave and / or place of occurrence of the second dicrotic notch included in the cuff pulse wave as the reference point Te is to contain.

[0009]

In this way, the reference point occurrence place determining means determines the occurrence place of the dichroic notch contained in the pulse wave based on the average value of the waveform calculated by the average value calculating means. Therefore, even when the dichroic notch cannot be clearly recognized in the pulse wave, the generation timing of the dichroic notch can be accurately detected. That is, physiologically, the fact that the end-systolic blood pressure in an artery can be approximated by the mean blood pressure of that artery is used, and the part of the pulse wave corresponding to that mean blood pressure value is defined as the time of dichroic notch occurrence. By doing so, the generation timing of the dichroic notch corresponding to the closure timing of the aortic valve can be determined even if the pulse wave shape cannot be clearly recognized. Therefore, the pulse wave propagation velocity information is accurately calculated based on the time difference between the dichroic notches determined as described above in the pulse waves generated from the arteries of two parts of the living body as reference points. To be done. For example, if the rising point is used as the reference point, the shape of the valley of the pulse wave (near the lower peak) is gradual, so sufficient reproducibility and accuracy cannot be obtained in signal processing technology, and the upper peak generation point is In the case of using the reference point, the control as the reference point could not be obtained because the peak is shifted by the influence of the reflected wave even if sufficient accuracy is obtained in the signal processing technique.

[0010]

[Other Aspects of the Second Invention] Preferably, the first cuff is wound around the upper limb of the living body so that the first cuff is
The cuff pulse wave detecting device is for detecting an upper limb cuff pulse wave generated from an artery of the upper limb, and the second cuff is wound around the lower limb of the living body, thereby the second cuff pulse wave detecting device. Is for detecting a lower limb pulse wave generated from an artery of the lower limb, and the pulse wave velocity information detecting device detects pulse wave velocity information between the artery of the upper limb and the artery of the lower limb. Is. With this configuration, the pulse wave velocity is based on the time difference between the reference point of the cuff pulse wave from the first cuff wrapped around the upper limb and the reference point of the pulse wave from the second cuff wrapped around the lower limb. The pulse wave obtained from the first cuff or the second cuff for which information is accurately calculated tends to have a blunt waveform, and the dichroic notch cannot be clearly recognized in many cases. By determining, the accurate propagation velocity information can be obtained even with the pulse wave obtained from the first cuff or the second cuff.

Further, preferably, the reference point generation place determining means is calculated by the average value calculating means at a two-dimensional coordinate consisting of a time axis and a cuff pulse wave axis indicating the magnitude of the cuff pulse wave. The point where the line indicating the average value of the waveform and the cuff pulse wave intersect is determined as the location where the dichroic notch occurs. By doing this, physiologically, the end-systolic blood pressure in an artery can be approximated by the average blood pressure of that artery, and the portion of the pulse wave corresponding to that average blood pressure value is dichroic. By setting the notch generation time, the dichroic notch generation location can be accurately determined even when it is difficult to recognize the dichroic notch generation location.

Also, preferably, the average value calculating means is
Since the average value P _av of the pulse wave is calculated by dividing the integral value of the pulse wave in the predetermined section of the pulse wave by the length of the section, the generation timing of the dichroic notch DN is accurately determined, and the pulse The accuracy of the wave propagation velocity information is improved.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram illustrating the configuration of a pulse wave velocity information detection device 10 with a dichroic notch detection function to which the present invention is applied.

The pulse wave velocity information detector 10 shown in FIG.
A left ankle cuff 18L and a right ankle cuff 18R are wound around the left ankle 12L and the right ankle 12R of the patient 16, respectively.
The left arm cuff 20L and the right arm cuff 20R are wound around the upper left arm 14R and the upper right arm 14L of the patient 16, respectively. These cuffs 18L, 18R, 20L, 20R are
This is a compression band that compresses the wound portion, and has a rubber bag inside a band-shaped outer bag made of a non-extensible material such as cloth or polyester.

The left and right upper arm cuffs 20L and 20R are pipes 2.
2b and 22a are connected to the pulse wave detector main body portions 24b and a, respectively, and the left and right ankle cuffs 18L and 18R are connected to the pulse wave detector main body portions 24d and c via the pipes 22d and c, respectively.
Respectively connected to.

These four pulse wave detector main body portions 24a,
Since b, c, and d have the same configuration as each other, the pulse wave detecting device main body 24b connected to the left upper arm cuff 20L is connected.
As an example, the configuration of the pulse wave detection device main body 24 will be described.
The pulse wave detecting device main body 24b includes a pressure regulating valve 26b, a pressure sensor 28b, a static pressure discriminating circuit 30b, a pulse wave discriminating circuit 32b,
A pipe 34b and an air pump 36b are provided, and the pipe 22b is connected to a pressure sensor 28b and a pressure regulating valve 26b. Further, the pressure regulating valve 26b is connected to the air pump 36b via the pipe 34b.

The pressure regulating valve 26b regulates the pressure of the high-pressure air generated by the air pump 36b and supplies it to the upper left arm cuff 20L, or supplies the air in the upper left arm cuff 20L. By exhausting the air, the pressure inside the cuff 20L for the upper left arm is adjusted.

The pressure sensor 28b is a cuff 20L for the upper left arm.
The internal pressure is detected and a pressure signal SP _b representing the pressure is supplied to the static pressure discrimination circuit 30b and the pulse wave discrimination circuit 32b, respectively. Static pressure filter circuit 30b includes a low-pass filter, steady pressure or left upper arm cuff 20L of compressive pressure contained in the pressure signal SP _b (hereinafter, referred to as the left upper arm cuff pressure PC _b the pressure) the cuff pressure signal representative of the SK _b is discriminated and the cuff pressure signal SK _b is supplied to the electronic control unit 38 via an A / D converter (not shown).

The pulse wave discrimination circuit 32b is a bandpass filter.
Equipped with pressure signal SP_bLeft arm pulse wave signal, which is the vibration component of
SM_bBy discriminating the frequency of the left upper arm pulse wave signal SM_bThe figure
Supply to the electronic control unit 38 via an A / D converter not shown
To do. This left arm pulse wave signal SM _bIs for the upper arm cuff 20L
Left upper arm pulse wave WB from the artery of left upper arm 14L, which is compressed more
_LRepresents the cuff 20L for the upper left arm and the pulse wave detection device.
The main body 24b functions as the left upper arm pulse wave detecting device 40.
It

[0020] Similarly, right brachial pulse wave signal SM _a to be discriminated by the pulse-wave filter circuit 32a is a right brachial pulse wave WB _R, right brachial cuff 20R and the pulse wave detection device body 24a is right brachial pulse wave It functions as the detection device 42. The left ankle pulse wave signal SM _d discriminated by the pulse wave discriminating circuit 32 _d is the left ankle pulse wave WA _L , and the left ankle cuff 18 L and the pulse wave detector main body 24 d are the left ankle pulse wave detector 44. Function. The right ankle pulse wave signal SM _c discriminated by the pulse wave discriminating circuit 32c is the right ankle pulse wave WA _R , and the right ankle cuff 1
8R and the pulse wave detecting device main body 24c function as the right ankle pulse wave detecting device 46. Also, the upper left Udemyakuha WB _L, the right brachial pulse wave WB _R, ankle pulse wave WA _L, functions as a first pulse wave and the second pulse wave any two of the pulse wave of the right ankle pulse wave WA _R Then, the pulse wave detecting device that detects the pulse wave functions as the first pulse wave detecting device and the second pulse wave detecting device.

The electronic control unit 38 includes a CPU 48, R
The CPU 48 is configured by a so-called microcomputer including an OM 50, a RAM 52, and an I / O port (not shown), and the CPU 48 executes signal processing while utilizing the storage function of the RAM 52 according to a program stored in advance in the ROM 50. Thus, a drive signal is output from the I / O port to control the air pump 36 and the pressure regulating valve 26.
The CPU 48 controls the air pump 36 and the pressure regulating valve 26 to control the cuffs 18L, 18R, 20L, 20R.
Control the pressure inside and cuff 18L, 18R, 20
The blood pressure of the region where L and 20R are wound, that is, the left ankle 12L, the right ankle 12R, the upper left arm 14L, and the upper right arm 14R is measured according to, for example, the oscillometric method. CPU
At 48, a lower limb upper limb blood pressure index (for example, lower limb maximum blood pressure / upper limb maximum blood pressure) ABI for determining, for example, arterial stenosis is calculated based on the blood pressures of the right ankle 12R, the left upper arm 14L, and the right upper arm 14R. In addition, the CPU4
Numeral 8 executes arithmetic processing based on the signal supplied to the electronic control unit 38, so that the respective cuffs 18L, 18R, 20L, 2L are maintained at a pressure lower than the minimum blood pressure value.
The arterial waveforms of the left and right regions generated at 0R are detected and displayed on the display 54, and 2 of them are detected.
The first pulse wave and the second pulse wave, which are two cuff pulse waves, for example, the left and right pulse waves obtained from the upper arm are displayed on the display 54 in a state of being overlapped with each other.

FIG. 2 is a functional block diagram for explaining a main part of the control function of the CPU 48. Cuff pressure control means 60
An air pump 36a provided in the pulse wave measuring device 40, 42, 44, 46, 36b, 36c, 36d and the pressure regulating valve 26a, 26b, 26c, by controlling the 26 d, the cuff pressure PC _a, PC _b , PC _c , PC _d are controlled to a predetermined pulse wave detection pressure. Here, the pulse wave detection pressure is a pressure lower than the minimum blood pressure value at the site where the cuffs 18L, 18R, 20L, and 20R are attached, and the pulse wave signal discriminated by the pulse wave discriminating circuit 32. The pressure is such that the SM has a sufficient signal strength, and is set to, for example, 50 mmHg.

The left upper arm pulse wave detecting device 40, the right upper arm pulse wave detecting device 42, the left ankle pulse wave detecting device 44, and the right ankle pulse wave detecting device 46 are operated by the cuff pressure control means 60 for each cuff 18.
L, 18R, 20L, 20R of the cuff pressure PC _a, PC _b, PC
_{With c} and PC _d maintained at the pulse wave detection pressure,
Upper left arm 14L, upper right arm 14R, left ankle 12L, right ankle 1
A CPU 4 that detects arterial waves generated from the 2R arteries in synchronization with each other, that is, an upper left arm pulse wave, an upper right arm pulse wave, a left ankle pulse wave, and a right ankle pulse wave, and functions as a storage device.
The data is stored in the RAM 52 in the RAM 8.

The dichroic notch detecting means 62 is
Left upper arm pulse wave detection device 40, right upper arm pulse wave detection device 4
2. Left ankle pulse wave detector 44, right ankle pulse wave detector 46
When the cuffs 18L, 18R, 20L, and 20R each detect a pulse wave P (t) that is a pressure vibration that occurs in synchronization with the heartbeat and pulsates every beat, the dichroic notch detecting means 62 detects the pulse wave P (t). The position of the dichroic notch of each pulse wave is detected. That is, the dichroic notch detection means 62 calculates the average value Pav of the waveform of a predetermined section in each pulse wave P (t).
And an occurrence location determining means 66 for determining the occurrence location of the dichroic notch contained in the pulse wave based on the average value Pav of the waveform calculated by the average value calculating means 64.
And detecting the generation position DN of the dichroic notch included in each pulse wave P (t).

In the average value calculating means 64, for example,
The signals representing the first pulse wave and the second pulse wave are P ₁ (t) and P
₂ (t), the pulse wave P ₁ (t) and P ₂ (t) from a predetermined time t _a to a predetermined time t _b thereafter (t _b −
by dividing each by t _a) the integral value at ∫P ₁ (t) and ∫P ₂ (t) the time interval (t _b -t _a), the mean value P _av1 and P _av2 waveform of the pulse wave, respectively It is calculated. For example, if the pulse wave P ₁ (t) and P ₂ where (t) is represented respectively by the digital value of the time-discrete system the predetermined sampling period, 1 of the pulse wave P ₁ (t) and P ₂ (t) The integral value of the pulse wave ∫ in the time section that is an integer (including 1) times the wavelength
By dividing P ₁ (t) and ∫P ₂ (t) by the wave number included in the time interval, average values P _av1 and P _av2 of the pulse wave are calculated, respectively. Here, if the pulse waves P ₁ (t) and P ₂ (t) are calibrated with the blood pressure measurement value using the cuff 18L and are pressure pulse waves representing the pressure in the artery, The average values P _av1 and P _av2 of the waveform of the pulse wave are values indicating the average blood pressure.

In the place of occurrence determining means 66, as shown in FIG. 3, for example, in the two-dimensional coordinates consisting of the time axis 68 and the pulse wave axis 70 indicating the magnitude of the cuff pulse wave, the mean value calculating means 64 is used. The _points where the broken _lines showing the average values P _av1 and P _av2 of the calculated waveforms and the falling portions of the cuff pulse _waves P ₁ (t) and P ₂ (t) intersect are the dichroic notch generation points DN ₁ and DN. Determined as ₂ .

The pulse wave velocity information calculating means 72 uses the first pulse wave P ₁ (t) as the dichroic notch occurrence locations DN ₁ and DN ₂ determined by the occurrence location determining means 66.
And used as a reference point of the second pulse wave P ₂ (t), of the dicrotic notch of the first pulse wave P ₁ generates a dicrotic notch (t) where DN ₁ and the second pulse wave P ₂ (t) Occurrence location D
The time difference DT with N ₂ (= t ₂ −t ₁ ) is calculated, and the pulse wave is calculated based on the time difference DT from the relationship (PWV = L / DT, L is the distance between the detection positions) stored in advance. The propagation velocity PWV is calculated. The display control means 74 causes the display 54 to display the pulse wave velocity information calculated by the pulse wave velocity information calculating means 72, that is, the time difference DT and / or the pulse wave velocity PWV.

FIG. 4 is a flow chart for explaining a main part of the control operation of the CPU 48 shown in FIG. 4, in step (hereinafter, step is omitted) S1, it is determined whether or not the activation condition of the pulse wave velocity detection operation is satisfied, for example, after the cuffs 18L, 18R, 20L, 20R are attached to the limbs, the activation push is performed. It is determined whether or not a button operation has been performed. While the determination of S1 is denied, that S1
When the determination is affirmative, the pressures of the cuffs 18L, 18R, 20L, and 20R are rapidly increased substantially simultaneously in S2 corresponding to the cuff pressure control means 60. In the following S3, four 1s
It is determined whether or not all the cuff pressures P _{C of} 8 L, 18 R, 20 L, and 20 R have exceeded a preset target compression pressure P _CM at a value set to exceed the systolic blood pressure of the patient, for example, about 180 mmHg. It When the determination in S3 is denied, the cuff pressure P _C continues to be increased by repeatedly executing the above S2 and subsequent steps.

If the determination in S3 is affirmative, the subsequent S4
At the air pumps 36a, 36b, 36c, 36d
Are stopped and pressure regulating valves 26a, 26b, 26c, 26d
Each cuff 18L, 18R, 20L, 20R
The internal pressure is a predetermined slow-down pressure rate, for example 3 mmHg
It can be lowered at a slow speed of about / sec. Then, the blood pressure of the limbs is measured by executing the blood pressure value determination routine of S5 corresponding to the blood pressure value determination means in such a gradual step-down process. That is, the amplitude of the cuff pulse wave represented by the pulse wave signal SM ₁ sequentially supplied from the pulse wave discrimination circuit 36 is determined for each beat, and the well-known oscillometric blood pressure value is determined based on the change in the amplitude. The first systolic blood pressure value BP1 _RSYS, etc. on the right foot side is determined according to the determination algorithm, and similarly, the pulse wave discrimination circuits 32a, 32b, 3
Based on the change in the amplitude of the cuff pulse wave represented by the pulse wave signal SM ₂ supplied from 2c and 32d, the systolic blood pressure value BP _{SYS and the} like are determined according to the oscillometric blood pressure value determination algorithm. When the blood pressure measurement by the blood pressure value determination routine of S5 is not completed, the above S4 and subsequent steps are repeatedly executed.

However, the blood pressure value determination routine of S5 is
When completed, the process proceeds to S6 corresponding to the cuff pressure control means 60.
The pressure regulating valves 26a, 26b, 26c and 26d are controlled.
Cuffs 18L, 18R, 20L, 20
Cuff pressure PC in R_a, PC_b, PC _c, PC_dIs the lowest blood, for example
Pulse wave detection set to about 50 mmHg, which is sufficiently lower than the pressure value
The pressure is maintained. Then, the pulse wave velocity information calculation of S7
The exit routine is executed as shown in FIG.

In FIG. 5, in S71, a pulse wave detecting device is used.
The pulse wave supplied from 40, 42, 44, 46 respectively
At least one beat, preferably a predetermined number of beats are read
It Subsequently, S72 corresponding to the average value calculating means 64.
Then, for each pulse wave read in S71, the waveform
Average value P of_avAre calculated respectively. Then the occurrence
In S73 corresponding to the place determining means 66, each pulse wave
And the average value P of the above waveform _avAnd the falling part of the waveform
The intersecting part is the position of the dichroic notch DN
Will be decided.

Next, the pulse wave velocity information calculating means 7
In S74 corresponding to 2, the pair of pulse waves among the above pulse waves, for example, the first pulse wave that is the pulse wave of the upper arm 14L and the ankle 1
The time difference DT between the dichroic notches DN ₁ and DN ₂ in the second pulse wave that is the 2 L pulse wave is calculated. Next, in S75, which similarly corresponds to the pulse wave velocity information calculating means 72, the relationship (PWV = L) stored in advance is stored.
/ DT, L is the distance between the detection positions), and the pulse wave velocity PWV is calculated based on the time difference DT.

Returning to FIG. 4, in S8, based on the blood pressure value measured in S5, for example, the lower limb (ankle) systolic blood pressure value is divided by the upper limb (upper arm) systolic blood pressure value to obtain the lower limb upper limb blood pressure index ABI ( Ankle Brachium Blood Pressur
e Index) is calculated. Then, the display control means 74
In S9 corresponding to, the pulse wave velocity PWV calculated in S7 and the lower limb upper limb blood pressure index ABI calculated in S8 are displayed on the display 54.

As described above, according to the present embodiment, the average value calculating means 64 is caused by the occurrence place determining means 66 (S73).
Since the place where the dichroic notch DN included in the pulse wave is generated is determined based on the average value P _av of the waveform calculated in (S72), even if the dichroic notch cannot be clearly recognized in the pulse wave, The generation timing of the notch DN is accurately detected. That is,
Physiologically, the fact that the end-systolic blood pressure in an artery can be approximated by the mean blood pressure of that artery is used, and the part of the pulse wave corresponding to that mean blood pressure value is taken as the time of occurrence of the dichroic notch DN. As a result, the generation timing of the dichroic notch DN corresponding to the closure timing of the aortic valve is determined even if the pulse wave shape cannot be clearly recognized. Therefore, the pulse wave propagation velocity information PWV is determined based on the time difference DT between the dichroic notches DN determined as described above in the pulse waves generated from the two arteries of the living body as reference points. Is accurately calculated. For example, if the rising point is used as the reference point, the shape of the valley of the pulse wave (near the lower peak) is gradual, so sufficient reproducibility and accuracy cannot be obtained in signal processing technology, and the upper peak generation point is In the case of using the reference point, the control as the reference point could not be obtained because the peak is shifted by the influence of the reflected wave even if sufficient accuracy is obtained in the signal processing technique.

Further, according to this embodiment, the reference point (dichrotic notch DN ₁ ) of the cuff pulse wave from the cuff 14L or 14R wound around the upper arm 14 (upper limb) and the ankle 1 are provided.
The pulse wave propagation velocity information PWV is accurately calculated based on the time difference DT from the reference point (dichroic notch DN ₂ ) of the pulse wave from the cuff 18L or 18R wound around 2 (lower limbs). The pulse wave obtained from the first cuff or the second cuff tends to have a blunt waveform, and the dichroic notch cannot be clearly recognized in many cases. Therefore, the dichroic notch is determined as described above. 1
Accurate propagation velocity information can be obtained even with a pulse wave obtained from the cuff or the second cuff.

Further, according to the present embodiment, the generation place determining means 66 (S73) calculates the average value in the two-dimensional coordinates consisting of the time axis 68 and the cuff pulse wave axis 70 indicating the magnitude of the cuff pulse wave. The point at which the broken line showing the average value of the waveform calculated by the means 64 (S72) and the cuff pulse wave intersect is determined as the generation place DN of the dichroic notch, and therefore physiologically, in the artery. By utilizing the fact that the end-systolic blood pressure can be approximated by the mean blood pressure of the artery, the site corresponding to the mean blood pressure value in the pulse wave is determined as the dichroic notch DN occurrence time. Even if it is difficult to recognize the location of the DN, the location of the dichroic notch DN is accurately determined.

Further, according to the present embodiment, the average value calculating means 64 (S72) divides the integrated value of the pulse wave in a predetermined section of the pulse wave by the length of the section to average the pulse wave. Since the value P _av is calculated, the generation timing of the dichroic notch DN is accurately determined.

Although the embodiments of the present invention have been described above with reference to the drawings, the present invention can be applied to other aspects.

For example, the average value calculating means 64 (S72) of the above-mentioned embodiment divides the integrated value of the pulse wave in a predetermined section of the pulse wave by the length of the section to obtain the average value P _av of the pulse wave. However, the average value P _AV is calculated based on the maximum value P _S and the minimum value P _D of the pulse wave from the relationship [P _AV = (P _S −P _D ) / 3 + P _D ] stored in advance. It may be calculated.

Further, in the above embodiment, four pulse wave detecting devices 40, 42, 44, 46 were provided, but the number of pulse wave detecting devices other than four such as one or two. May be. In addition, these pulse wave detection devices 40, 42, 44,
Although all of 46 detect the pulse wave using the cuffs 18L, 18R, 20L, and 20R, a pressure pulse wave detecting device that detects the pulse wave using a pressure sensor that presses the artery may be used. . Further, as a pulse wave detection device, a photoelectric pulse wave detection probe for measuring oxygen saturation, a pressure pulse wave sensor of a type that detects a pressure pulse wave by pressing a predetermined artery such as a radial artery from above the epidermis, an arm An impedance pulse wave sensor that detects the impedance of a fingertip or the like through an electrode, a photoelectric pulse wave sensor that is attached to a fingertip or the like for pulse detection, or the like may be used.

The mounting position of the pulse wave detecting device is not limited to the upper arm or the ankle. For example, the pulse wave detecting device may be attached to the ankle joint instead of the ankle. Alternatively, a cuff may be attached to the thigh and a pulse wave detection device that detects a pulse wave from the cuff may be used. If pulse waves are detected in the thigh and ankle, arterial stenosis between the thigh and ankle can be determined.

In the above embodiment, in the pulse wave,
The intersection of the average value P _{AV of the} waveform and the falling portion of the pulse wave P (t) was determined as the occurrence point DN of the dichroic notch, but the value derived from the average value P _AV, for example, the average value of the waveform The intersection point of P _AV + α or the average value P _AV −β of the waveform and the falling portion of the pulse wave P (t) may be determined as the generation point DN of the dichroic notch.

The embodiments of the present invention have been described in detail above with reference to the drawings. However, this is merely an embodiment, and the present invention includes various modifications and improvements based on the knowledge of those skilled in the art. Can be implemented in.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating the configuration of a pulse wave velocity information detection device with a dichroic notch detection function to which the present invention is applied.

FIG. 2 is a functional block diagram illustrating a main part of a control function of the CPU of FIG.

FIG. 3 is a time chart explaining the operation of the dichroic notch detecting means of FIG.

FIG. 4 is a flowchart illustrating a main part of control operation of the CPU of FIG. 1, that is, a routine for detecting pulse wave velocity information of a living body and a lower limb upper limb blood pressure index detection routine.

5 is a flowchart illustrating an operation of a pulse wave velocity calculation routine of FIG.

[Explanation of symbols]

10: Pulse wave velocity information detector with dichroic notch detection function 40: Upper left arm pulse wave detector (pulse wave detector) 42: Upper right arm pulse wave detector (pulse wave detector) 44: Left ankle pulse wave detector Device (pulse wave detection device) 46: Right ankle pulse wave detection device (pulse wave detection device) 62: Dichroic notch detection means 64: Average value calculation means 66: Occurrence location determination means 72: Pulse wave propagation velocity information calculation means

Claims (6)

[Claims] 1. A pulse wave generated from an artery of a living body,
A dichroic notch detection device for detecting a dichroic notch that is a waveform corresponding to the closure of an aortic valve, wherein an average value calculation means for calculating an average value of a waveform of a predetermined section in the pulse wave, and the average value A dichroic notch detection device, which includes an occurrence location determination means that determines the occurrence location of the dichroic notch included in the pulse wave based on the average value of the waveform calculated by the calculation means. 2. The average value calculating means calculates the average value of the pulse wave by dividing an integral value of the pulse wave in a predetermined section of the pulse wave by the length of the section. Pulse wave velocity information detector. 3. The first wound on each of two parts of the living body
A first cuff pulse wave detecting device and a second cuff pulse which respectively include a cuff and a second cuff, and detect a first cuff pulse wave and a second cuff pulse wave which are pressure oscillations generated in the first cuff and the second cuff. Wave detection device, generation time difference between the reference point of the first cuff pulse wave detected by the first cuff pulse wave detection device and the reference point of the second cuff pulse wave detected by the second cuff pulse wave detection device A pulse wave velocity information detecting device for detecting pulse wave velocity information on the basis of, wherein an average value is calculated for calculating an average value of waveforms in a predetermined section in the first cuff pulse wave and / or the second cuff pulse wave. Means and a criterion for determining, as the reference point, a location where a dichroic notch included in the first cuff pulse wave and / or the second cuff pulse wave is generated based on the average value of the waveform calculated by the average value calculating means. The point occurrence place determining means, Pulse wave velocity information detection apparatus is Dressings. 4. The first cuff is wound around the upper limb of the living body, whereby the first cuff pulse wave detecting device detects an upper limb cuff pulse wave generated from an artery of the upper limb. Since the second cuff is wound around the lower limb of the living body, the second cuff pulse wave detection device detects a lower limb pulse wave generated from an artery of the lower limb, and the pulse wave propagation velocity information. The pulse wave velocity information detecting device according to claim 3, wherein the detector detects pulse wave velocity information between the artery of the upper limb and the artery of the lower limb. 5. The reference point occurrence place determining means is an average of the waveforms calculated by the average value calculating means in a two-dimensional coordinate consisting of a time axis and a cuff pulse wave axis indicating the magnitude of the cuff pulse wave. The pulse wave velocity information detecting apparatus according to claim 3 or 4, wherein a point where a line indicating a value and the cuff pulse wave intersect is determined as a place where the dichroic notch occurs. 6. The average value calculating means calculates the average value of the pulse wave by dividing an integral value of the pulse wave in a predetermined section of the pulse wave by the length of the section. The pulse wave velocity information detection device according to any one of 1 to 5.