JPH05207978A - Instrument for measuring fluctuation in blood pressure in non-restrained training - Google Patents

Abstract

PURPOSE:To measure the fluctuation in blood pressure in training without restraining at every one heart beat. CONSTITUTION:The light beams cast at prescribed cycles from light sources 1, 2 of different wavelengths are absorbed and reflected by the superficial blood vessels of a living body. The respective reflected beams are detected by a common photodetector 3 and the electric signal corresponding to the photodetected quantity is sent to a multiplexer 5. The multiplexer 5 separates the electric signal by each of the respective wavelengths and the separated electric signal are sent to variable gain amplifies 6, 7, by which the electric signals PR and PIR are obtd. These electric signals are inputted to band-pass filters 8, 9, from which pulse wave signals DELTAPR, DELTAPIR having the fluctuation component and disturbance component of the reflected beams by the blood vessel pulse wave are obted. These signals are inputted to a differential amplifier 10 to obtain a pulse wave signal PS from which the disturbance is removed. This signal is inputted to a differentiator 11, by which a differential pulse wave signal deltaPS is obtd. A differential electrocarbiograph waveform deltaCG is obtd. from an electrode 13 and an electrocardiograph 14. A pulse wave propagation velocity is obtd. from the both. The propagation velocity is sent from a transmitter 21 to a receiver. The blood pressure value of every one heart beat is estimated from this pulse wave propagation velocity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring blood pressure fluctuation during unrestrained exercise.

[0002]

2. Description of the Related Art Conventionally, as a non-invasive blood pressure measuring method, an oscillometric method using a minute pressure displacement in a compression zone (cuff), a volume vibration method and a volume compensation method using a photoelectric pulse wave signal, a Korotkoff sound There are auscultation methods and the like, which have been used for exercise load measurement using a treadmill, an ergometer, and the like.

[0003]

However, in these measuring methods, the movement of the subject using a treadmill, an ergometer, etc. can be measured only with an exercise load, and in that case, the movement of the subject is considerably limited. .. Therefore, measuring blood pressure fluctuations during exercise load in the original sense (during exercises such as marathon and ball game) is because these methods are vulnerable to disturbance due to body movements and any of these methods presses the measurement site. Since a cuff, a pressure source (pump) and the like have to be used, the sensor unit and the measuring device themselves are large in size, and it has been impossible to measure blood pressure fluctuations without restraint.

[0004]

An apparatus for measuring blood pressure fluctuation during unconstrained exercise according to the present invention includes a portable data transmitter mounted on the body for collecting and transmitting a biological signal, and receiving the transmitted biological signal. In an apparatus for measuring blood pressure fluctuation during unrestrained exercise, which comprises an interface section for performing arithmetic processing and displaying the result or transmitting the result to another biological signal display monitor, the data transmitting section uses the pulse wave of the superficial artery as a photoelectric pulse wave signal. As a pulse wave sensor section consisting of a photoelectric element taken out from the measurement site, an electrode section for obtaining an electrocardiographic signal used to obtain a pulse wave velocity, and a disturbance due to body movement is removed from the photoelectric pulse wave signal of two wavelengths. A disturbance removing unit, an arithmetic control unit that obtains a pulse wave transit time by differentiating the photoelectric pulse wave signal and the electrocardiographic signal, and a transmitting unit that sequentially transmits each of these data to the interface unit, By serial interface uses pulse wave velocity in each one heartbeat, and comprises a calculation control unit for estimating the blood pressure values for each one heartbeat.

[0005]

The present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention (data transmission section).
5 is a block diagram showing the configuration of an embodiment (interface unit) of the present invention, FIG. 3 is an external view of an optical sensor, FIG. 4 is an explanatory diagram showing the principle of disturbance removal, and FIG.
FIG. 6 is an explanatory diagram showing an example of the relationship between the blood vessel pressure and the pulse wave velocity, and FIG. 6 is an explanatory diagram showing an example of how to obtain the pulse wave velocity.

First, the outline of the present invention will be described.

The present invention pays attention to the fact that the pulse wave velocity changes depending on the intravascular pressure, and the differential waveform of the photoelectric pulse wave signal and the differential waveform of the electrocardiographic waveform or the photoelectric pulse wave signal of a portion different from the measurement site The pulse wave velocity is calculated from the time difference of the differential waveform and the anatomical blood vessel length, and the blood pressure value measured in advance in the exercise load and the conversion curve that converts the pulse wave velocity to the intravascular pressure are used to measure the blood vessel for each heartbeat. Estimate the internal pressure.

According to this method, it is possible to reduce the number of sensors to be attached to the living body, and further to reduce the restriction of exercise due to the attachment of the measuring device by using wireless for data transmission. In addition, when the photoelectric pulse wave signal is obtained, the difference in the transfer characteristics into the living body depending on the wavelength of light is used, multiple wavelengths are used for the light emitting element, and time-division measurement is performed. By taking the difference between the waveforms, it is possible to extract only the photoelectric pulse wave signal component due to the blood volume change, and it is possible to remove the body movement disturbance due to exercise.

Referring to FIG. 1, which is a diagram showing a data transmission section, a light source 1 emits red light having a wavelength of about 660 nm, and a light source 2 emits near infrared light having a wavelength of about 804 nm. It emits light. Light emitted from the light sources 1 and 2 is absorbed and reflected by a superficial blood vessel of a living body (not shown), and each reflected light is received by the common light receiving element 3 shown in FIG. In addition, these light sources 1 and 2,
It is turned on alternately in a predetermined cycle. The light-receiving element 3 is composed of, for example, a wide-wavelength phototransistor or photodiode having sensitivity in the emission wavelength range of the light-emitting elements 1 and 2, and outputs an electric signal PS having a magnitude corresponding to the amount of received light to the multiplexer 5. To do. The multiplexer 5 is switched based on a switching signal MP, which will be described later, corresponding to lighting signals R and IR, which will be described later, so that the electric signal PR corresponding to red light is supplied to the variable gain amplifier 6 and the electric signal PR corresponding to near infrared light is supplied. The signal PIR is output to each variable gain amplifier 7. The variable gain amplifiers 6 and 7 amplify the electric signals P and PIR corresponding to the pulse wave, and output the electric signals PRD and PIRD to the band pass filters 8 and 9, respectively. Band pass filter 8, 9
Is a low frequency from the input electric signals PRD, PIRD.
The pulse wave signals ΔPR and ΔPIR having the fluctuation component and the disturbance component of the reflected light due to the pulsation are removed respectively from the high frequency components, and these pulse wave signals ΔPR and ΔPIR are input to the differential amplifier 10.

In the differential amplifier 10, the pulse wave signals ΔPR, Δ
The pulse wave signal ΔPS from which the difference of PIR is taken and the disturbance is removed is input to the differentiating circuit 11 to obtain the differential pulse wave signal δPS. This differential pulse signal δPS is passed through the A / D converter 12 to I /
It is supplied to the O port 17.

The I / O port 17 is further provided with a plurality of electrodes 13 mounted on the subject's chest or the like, and an electrocardiograph 14 for detecting an electrical signal generated in association with the activity of the heart.
Are connected. The electrocardiograph 14 inputs the electrocardiographic waveform CG to the differentiating circuit 15. A differential electrocardiographic waveform δCG is obtained from the differentiating circuit 15. The differential electrocardiographic waveform δCG is supplied to the I / O port 17 via the A / D converter 16.

The I / O port 17 includes a CPU 18, a ROM 19, a RAM 20 and a transmitter 2 via a data bus line.
1 is connected to each. CPU18 is RAM2
The signal processing is executed according to a predetermined program in the ROM 19 while utilizing the memory function of 0, and the lighting signals R and IR are respectively supplied to the light sources 1 and 2 through the I / O port 17 and the lighting signals R and IR are supplied. The switching signal SW is supplied to the multiplexer 5 corresponding to IR, and
Based on the output pulse wave signal ΔPS of the differential amplifier 10, the gain switching signals RG and IRG are respectively supplied to the variable gain amplifiers 6 and 7 in a direction in which the influence of disturbance is reduced.
The pulse wave transit time is determined according to a predetermined algorithm from the differential pulse wave signal δPS and the differential electrocardiographic waveform δCG, and the pulse wave transit time is transmitted from the transmitter 21.

FIG. 2 is a diagram showing the interface unit of the present invention. The receiver 22 receives the data from the transmitter 21, and sends the data to the CPU 23 and RO via the data bus line.
M24, RAM25, I / O port 26, display 27,
The external interface 28 and the input device 29 are respectively connected. The CPU 23 executes signal processing according to a program predetermined in the ROM 24 while utilizing the storage function of the RAM 25, and the blood pressure value uniquely determined from the relationship between the blood pressure value of the subject and the pulse wave velocity that are input in advance. Via the I / O port 26
Or output to the external interface 28 for each heartbeat.

Next, the principle of removing the disturbance due to the body motion and the principle of estimating the blood pressure value obtained from the pulse wave velocity are as follows.

First, regarding the principle of disturbance removal by body movement, FIG. 3 is an external view of an optical sensor including light emitting elements 1 and 2 and a light receiving element 3. The partial view (A) of FIG. 3 is a view seen from the surface worn on the human body, and the partial view (B) is the surface worn on the human body on the lower side. The shield 4 removes the influence of direct light from the light emitting element 3. Light emitting elements 1 and 2 having different wavelengths are used, and the light emitting elements 1 and 2 and the light receiving element 3 are installed so that the geometrical positional relationship is the same. This optical sensor is closely fixed to the surface of the living body with an adhesive tape or the like so as to sandwich the superficial blood vessel between the light emitting elements 1 and 2 and the light receiving element 3. If the photoplethysmographic signal can be observed even in a place where there is no superficial blood vessel, the measurement by this method is possible.

FIG. 4 shows the principle of disturbance removal by body movement. It is known that the transfer characteristics of light into a living body greatly differ depending on the wavelength. Therefore, it suffices to perform measurement using a plurality of wavelengths having different transmission characteristics into the living body and perform an operation so as to separate only the measurement target, for example, 2
When measuring by wavelength, the wavelength λ2, which is not greatly affected by blood flow modulation, detects body movement disturbance due to relative position fluctuations, and the influence of modulation due to scattering and absorption by blood flow and the disturbance due to body movement. It is possible to remove the influence of the disturbance due to the body movement by taking the difference from the detection information by the wavelength λ1 including the. It should be noted that the gain coefficients of the variable gain amplifiers 6 and 7 for removing the disturbance due to the body movement are changed by the gain switching signals RG and IRG calculated by a predetermined program at any time so that the influence of the disturbance due to the body movement is minimized. Is set.

The blood pressure value estimation principle obtained from the pulse wave velocity is as follows. FIG. 5 shows the relationship between pulse wave velocity and defect internal pressure. As shown in the figure, the pulse wave velocity is slow when the intravascular pressure is low, and is high when the intravascular pressure is high. However, the pulse wave velocity is also affected by the properties of the blood vessel wall, and the curve differs for each individual, so measure the pulse wave velocity at some blood pressure value in advance and convert it for each individual. You need to know the curve. By using this conversion curve, the intravascular pressure can be estimated from the pulse wave velocity. Further, if this is performed for each heartbeat, it is possible to follow the blood pressure fluctuation for each heartbeat. FIG. 6 is an explanatory diagram for obtaining the pulse wave velocity from the differential pulse wave signal δPS and the differential electrocardiographic waveform δCG. The use of the differential waveform instead of the original waveform is used to clarify the rising points of the Q wave and the photoelectric pulse wave of the electrocardiogram. Furthermore, in order to prevent erroneous recognition of the waveform due to disturbances other than the rising point of the pulse wave, the pulse wave generally appears about 50 to 300 ms after the Q wave, so the gate is opened only in this section. Only in this section, the rising point of the differential pulse wave will be searched. In this way, the time difference between the rising points of the Q wave and the pulse wave is obtained, and division is performed by this and the anatomical blood vessel length between the median line and the photoelectric pulse wave measurement point estimated in advance to obtain the pulse wave propagation velocity. Incidentally, instead of the differential electrocardiographic waveform, it is possible to obtain the pulse wave velocity by a similar method by using the differential pulse wave simultaneously measured at a site different from the above-mentioned measurement site, and thereby the blood pressure value can be obtained. Can be estimated.

[0019]

As described above, the apparatus for measuring blood pressure fluctuation during unrestrained exercise according to the present invention can measure the fluctuation for each heartbeat by using the pulse wave velocity in order to obtain the blood pressure fluctuation. Since the cuff for compression and the pump are not used, it is easy to downsize the sensor unit and the portable device, and it is possible to manufacture a device that does not restrict the movement of the subject.

Furthermore, since a plurality of wavelengths having different transmission characteristics into the living body are used, a photoelectric pulse wave waveform free of disturbance caused by body movement can be obtained, and stable measurement is possible even during exercise. In this sense, the blood pressure fluctuation for each heartbeat during the exercise load can be measured without restraint, and the effect of the exercise load or the heart disease test under the exercise load can be performed.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment (data transmission unit) of the present invention.

FIG. 2 is a block diagram showing the configuration of an embodiment (interface unit) of the present invention.

[Figure 3] External view of the optical sensor

FIG. 4 is an explanatory diagram showing the principle of disturbance removal.

FIG. 5 is an explanatory diagram showing an example of the relationship between intravascular pressure and pulse wave velocity.

FIG. 6 is an explanatory diagram showing an example of how to obtain a pulse wave velocity.

[Explanation of symbols]

 1, 2 Light emitting element 3 Light receiving element 6,7 Variable gain amplifier 8,9 Band pass filter 10 Differential amplifier 11,15 Differentiator 21 Transmitter

Claims (2)

[Claims] 1. A portable data transmitter mounted on the body for collecting and transmitting a biological signal, and receiving the transmitted biological signal to perform arithmetic processing to display the result or transmit it to another biological signal display monitor. In an apparatus for measuring blood pressure fluctuation during unrestrained exercise, which comprises an interface section, the data transmission section includes a pulse wave sensor section including a photoelectric element that extracts a pulse wave of a superficial artery as a photoelectric pulse wave signal from a measurement site, and pulse wave propagation. An electrode section for obtaining an electrocardiographic signal used to obtain a velocity, a disturbance removing section for removing a disturbance due to body movement from a photoelectric pulse wave signal of two wavelengths, and a pulse by differentiating the photoelectric pulse wave signal and the electrocardiographic signal. A calculation control unit for obtaining a wave propagation time and a transmission unit for sequentially transmitting each of these data to the interface unit, wherein the interface unit uses the pulse wave velocity for each heartbeat According to another aspect of the present invention, there is provided an arithmetic control unit for estimating a blood pressure value for each heartbeat, which is an apparatus for measuring blood pressure fluctuation during unrestrained exercise load. 2. The electrocardiographic signal is differentiated to detect the Q wave of the electrocardiographic signal from the differential, and the gate at the output is opened and the gate is closed after a predetermined time has elapsed. The blood pressure fluctuation measuring device under unrestrained exercise load according to claim 1.