JP3533122B2 - Pulse wave monitor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulse wave monitor for observing a pulse wave by applying vibration to a blood vessel in a living body and detecting the vibration propagated in the blood vessel.

[0002]

2. Description of the Related Art Conventionally, as a method of monitoring a pulse wave, a "pulse wave detecting device" disclosed in Japanese Patent No. 2572088 is known. This device includes a pressing member that presses against the body surface of the human body, a plurality of contactors to which the pressure of the pulse wave from the body surface is transmitted while the pressing member is pressed against the body surface, and the contactor. A pressure sensor for detecting the pressure vibration and a driving unit for moving the pressure sensor are provided, and the pulse wave is detected by the pressure sensor.

In addition, as a method for continuously measuring biological parameters non-invasively by applying vibration to a blood vessel in a living body and detecting and analyzing the vibration propagated in the blood vessel, there is a method disclosed in Japanese Patent Publication No.
"Apparatus and method for measuring induced perturbation to measure physiological parameter" is disclosed in Japanese Patent Publication No. 506024. This device, including blood pressure,
It analyzes and tracks vascular wall compliance, ventricular contraction strength, vascular resistance, blood volume, cardiac output, myocardial contractility and many other physiological parameters. In this device, in order to continuously measure a patient's physiological parameters, periodic calibration measurements representing the patient's physiological parameters are obtained. An exciter is placed on the patient's artery to induce an oscillating wave in the arterial blood. Then, a vibration detector is arranged at another position on the artery to detect a vibration wave, and a signal representing a blood parameter is obtained. The processor processes the calibration measurements and the vibration detector signal to continuously measure the patient's physiological parameters.

[0004]

However, in the device disclosed in Japanese Patent Registration No. 2572088, in order to detect the pulse wave, in addition to the pressure sensor, a plurality of contactors and the contactors thereof are used. A pressing member for pressing is required. Moreover, the scale of the pressing member for pressing the pressure sensor is large, and since the air pressure must be used for pressing, the living body mounting section becomes large and the burden on the patient is large. However, there is a problem that complicated control is required to press the pressure sensor.

Further, Japanese Patent Publication No. 9-506024 discloses that a signal of a vibration detector is A / D converted and the data is processed by a processor in order to continuously measure a physiological parameter of a patient. Have been described. In the processing of the processor, it is necessary to carry out multiplication of trigonometric functions, etc., which causes a problem that the scale of the apparatus and software becomes large and processing time is long.

The long processing time poses a serious problem when measuring biological information in real time. For example, when the blood pressure waveform measured by the device disclosed in Japanese Patent Publication No. 9-506024 is simultaneously monitored with the electrocardiogram waveform measured by another device, the former blood pressure waveform is always delayed. Recently, high-speed microprocessors have been put into practical use, but in order to perform the processing disclosed in Japanese Patent Publication No. 9-506024, a delay is always generated no matter how high-speed processing is performed. This delay can be a major clinical impediment.

The present invention has been made in order to solve the above-mentioned conventional problems, and detects the pulse wave by a simple method of mounting an exciter and a vibration detector with double-sided tape or the like. Provide an excellent pulse wave monitor capable of displaying a pulse wave signal without delay with a simple configuration of detecting a phase difference between a reference signal and a vibration detection signal without A / D converting the signal or processing with a processor. To do.

[0008]

A pulse wave monitor according to the present invention is an oscillator that oscillates a signal at an arbitrary frequency and amplitude, an exciter that oscillates an artery in a living body by the oscillation signal of the oscillator, and the exciter. A sticking means for sticking to the living body, a vibration detector for converting the vibration from the exciter propagating on the artery into an electric signal, a sticking means for sticking the vibration detector to the living body, and oscillated by the oscillator. A phase comparator that detects a phase difference between the signal and the electric signal converted by the vibration detector, a phase difference voltage converter that converts the output of the phase comparator into a voltage indicating a phase difference, and the phase difference voltage converter And a pulse wave waveform display means for displaying the pulse wave signal output from the low pass filter. To have. With this configuration, the output from the vibration detector can be output by a simple configuration that displays the pulse wave signal by detecting the phase difference between the signal transmitted from the exciter and the signal propagating on the arterial blood vessel detected by the vibration detector. A
The pulse wave signal can be displayed and observed without delay with the minimum component configuration without performing D / D conversion.

The pulse wave monitor according to the present invention comprises an exciter voltage comparator for comparing the oscillation signal from the oscillator with a preset voltage level and outputting the result of the comparison, and an electric signal converted by the vibration detector. And a detection signal voltage comparator which outputs a result of comparison with a preset voltage level, wherein the phase comparator includes an output signal from the exciter voltage comparator and an output signal from the detection signal voltage comparator. It has a configuration of detecting a phase difference. With this configuration, the signal transmitted from the generator and the signal propagating on the arterial blood vessel detected by the vibration detector are compared with the preset voltage level, and are binarized. The rising edge of the detected signal is clear, the phase detection capability is improved, and stable phase comparison can be performed.

In the pulse wave monitor according to the present invention, the pulse wave signal output from the low pass filter is converted into a digital signal.
A / D converter for D / A conversion, waveform memory for storing the A / D converted digital signal, and D / A conversion for D / A converting the digital signal stored in the waveform memory into a pulse wave signal And a pulse wave waveform display means for displaying the D / A converted pulse wave signal and the pulse wave signal output from the low pass filter, and the A / D converter, the D / A converter and the waveform memory. And a processor that operates. With this configuration, since the measured pulse wave waveform can be stored in the memory, the stored waveform can be arbitrarily redisplayed on the pulse wave waveform display means.

The pulse wave monitor according to the present invention comprises a blood pressure measuring means for measuring a systolic blood pressure and a diastolic blood pressure, a blood pressure calculating means for converting the A / D converted pulse wave signal into a continuous blood pressure waveform, and the blood pressure calculating means. And a continuous blood pressure waveform display means for displaying the continuous blood pressure waveform calculated in. With this configuration, the pulse wave waveform can be displayed as a continuous blood pressure waveform by performing the calibration by the blood pressure calculation means using the systolic blood pressure and the diastolic blood pressure measured by the blood pressure measurement means, so that the continuous blood pressure can be displayed non-invasively. The waveform can be measured.

To summarize the above-mentioned present invention, a pulse wave monitor according to the present invention comprises an oscillator for transmitting a signal for vibrating an artery, an exciter for converting the transmitted signal into a vibration and vibrating an artery in a living body, A vibration detector that detects the vibration propagating on the artery and converts it into an electric signal, a sticking means that sticks the exciter and the vibration detector to the living body stably and easily, and a signal oscillated by the oscillator and the vibration detector. A phase comparator that detects the phase difference from the signal converted to an electrical signal, a phase difference voltage converter that converts the output indicating the phase difference from the phase comparator into a voltage, and a phase difference voltage converter A low-pass filter that passes only the low-frequency component of the signal and a pulse wave waveform display unit that displays the output of the low-pass filter as a pulse wave signal are provided.

According to the present invention, which is configured as described above, it is possible to easily attach the exciter and the oscillator to the living body with a double-sided tape or the like, and to utilize the fact that the elasticity of the blood vessel changes according to the change of the pulse wave, By vibrating the arterial blood vessel with the exciter and detecting the vibration propagating in the blood vessel with the vibration detector, measuring the speed of the vibration propagating through the blood vessel as a phase change, and measuring the phase change as a pulse wave and displaying it. , The detected signal is A
An excellent pulse wave monitor capable of displaying a pulse wave without delay can be obtained with a simple configuration that does not perform D / D conversion or processing by a processor.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, based on FIG. 1 to FIG.
The first to third embodiments of the present invention will be described in detail.
First, a pulse wave monitor according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 5.

First, the configuration of the pulse wave monitor according to the first embodiment of the present invention will be described with reference to FIG. In FIG. 1, a vibration oscillator 1 is a vibration oscillator capable of oscillating a signal at an arbitrary frequency and amplitude that are most effective for a subject of several Hz to several 1000 Hz. The signal oscillated from the vibration oscillator 1 is applied to the subject (living body) by the exciter 2.
Vibrates the arterial blood vessels. Suitable elements for the vibration oscillator 1 include a piezoelectric ceramic element that can efficiently convert an electric signal into vibration. Vibration detector 3
Is a sensor that detects the vibration from the exciter 2 propagated through the arterial blood vessel of the subject and converts it into an electric signal. Suitable elements for the vibration detector 3 include a piezoelectric ceramic element that can efficiently convert vibration into an electric signal, PVDF (polyvinylidene fluoride), and the like. The sticking means 20 is the exciter 2.
When the vibration detector 3 is attached to the living body, it is attached to the skin to set the exciter 2 and the vibration detector 3 there. The phase comparator 4 uses the signal from the vibration oscillator 1 as a reference signal and detects the phase difference from the signal from the vibration detector 3. The phase difference voltage converter 5 converts the phase difference signal detected by the phase comparator 4 into different voltages based on the phase difference. The low pass filter 6 removes the high frequency component of the phase difference signal converted into the voltage. The signal from which this high frequency component is removed becomes the pulse wave signal. The pulse wave waveform display means 7 displays the waveform of the pulse wave signal thus detected.

Next, with reference to FIG. 2, the mounting state of the exciter 2 and the vibration detector 3 on the living body will be described. FIG. 2 shows a state in which the exciter 2 and the vibration detector 3 are mounted on the radial artery of the wrist 21 as an example thereof. Both the exciter 2 and the vibration detector 3 are attached to the skin of the wrist 21 via the attaching means 20. A preferable example of the attaching means 20 is a double-sided tape.

It has been described above that the exciter 2 and the vibration detector 3 are preferably piezoelectric ceramic elements or the like, but the size effective in the first embodiment of the present invention is, for example, 1 cm to 2 cm in diameter. The element itself has a thickness of less than 1 mm, and even if a case is attached, the thickness is about 5 mm. Since the weight is also about 10 g, it can be sufficiently attached to the wrist 21 or the like with the double-sided tape, and the burden on the wearer is small.

Next, the principle of pulse wave measurement in the present invention will be described with reference to FIG. FIG. 3 shows a state in which the exciter 2 and the vibration detector 3 are attached from above the skin onto the radial artery 22 of the wrist 21 by the attaching means 20. The vibration waveform 23 propagating in the artery shown in FIG. 3 schematically represents the vibration propagating on the radial artery 22.
The vibration induced by the exciter 1 propagates in the radial artery 22, and the vibration propagated in the radial artery 22 is detected by the vibration detector 3. The pulse wave is measured by detecting the phase difference between the vibration detected by the vibration detector 3 and the vibration induced by the exciter 2.

Next, with reference to FIGS. 4 and 5, a method for detecting a phase difference between the vibration detected by the vibration detector 3 and the vibration induced by the exciter 2 in the first embodiment of the present invention. explain. The phase difference between these two vibrations is detected by the phase difference detector 4, the phase difference voltage converter 5, and the low pass filter 6.
Is performed using. That is, FIG. 4 shows an example of a circuit for realizing the respective functions of the phase difference detector 4, the phase difference voltage converter 5, and the low-pass filter 6, and FIG. 5 shows the phase comparison function and its result. 3 is a timing chart showing the above.

First, in FIG. 4, the signal from the vibration oscillator 1 is input to the phase comparator 4 as the reference signal a, and the signal from the vibration detector 3 is input to the phase comparator 4 as the comparison signal b. In the vibration oscillator 1 and the vibration detector 3, the signal levels of the reference signal a and the comparison signal b are scaled so as to match the input level of the phase comparator 4.

The two input signals (reference signal a and comparison signal b) to the phase comparator 4 are, as shown in FIG.
It is preferable to use Schmitt trigger inputs for the two inputs to the phase comparator 4 shown in FIG. 4, because a signal with an unclear edge such as a sine wave may be input.

The phase comparator 4 detects the rising difference between the reference signal a and the comparison signal b and inputs it to the phase voltage converter 5. The phase difference voltage converter 5 has a function generally called a charge pump, and together with the capacitor C of the low pass filter 6, converts the phase difference detected by the phase comparator 4 into a voltage and outputs the phase difference signal p. .

The operation of the phase difference voltage converter 5, that is, the charge pump in the first embodiment of the present invention will now be described with reference to FIG. Reference signal a and comparison signal b
When the output x of the phase comparator becomes the “H” level as a result of the phase comparison of, the FET Q1 of the phase difference voltage comparator 5 is turned on, and the capacitor C of the low pass filter 6 is charged. On the other hand, when the output y of the phase comparator becomes "H" level, F
ETQ2 is turned on and the capacitor C is discharged. When the two outputs x and y both become "H" level, FETQ
Both 1 and Q2 are turned off and become floating. In this way, the phase difference signal p as shown in FIG. 5 is output by charging / discharging the capacitor C or floating it by the phase difference between the reference signal a and the comparison signal b.

Further, as shown in FIG. 5, since the phase difference signal p is the output of the charge pump circuit by the phase difference voltage converter 5, it contains harmonic noise. Therefore, the low pass filter 6 removes this harmonic noise.
The signal from which the harmonic noise is removed by the low-pass filter 6 is the pulse wave signal m as the measurement result to be obtained in the present invention.
Is.

As described above, in the first embodiment of the present invention, the fact that the elasticity of the blood vessel changes according to the change of the pulse wave is utilized to vibrate the arterial blood vessel by the exciter 2 to propagate the blood vessel. The vibration is detected by the vibration detector 3, the speed of the vibration propagating through the blood vessel is measured as a phase change, and the phase change is measured as a pulse wave.

As described above, according to the first embodiment of the present invention, by simply attaching the exciter 2 and the vibration detector 3 with a double-sided tape or the like, the reference signal a and the comparison signal are added. Only by detecting the phase difference of b, it is not necessary to perform A / D conversion of the signal detected by the vibration detector 3 or to perform a processor operation, so that the pulse wave signal can be detected by the minimum component configuration and there is no delay. It has the effect that it can be displayed. According to the first embodiment of the present invention,
The elastic properties of blood vessels can also be measured at the same time, and it can be used for diagnosis of the progress of arteriosclerosis.

Next, a pulse wave monitor according to the second embodiment of the present invention will be described with reference to FIGS. 6 to 8. In FIG. 4, the vibration oscillator 1, the exciter 2, the vibration detector 3, the phase comparator 4, the phase difference voltage converter 5, the low-pass filter 6, the pulse wave waveform display means 7, and the pasting means 20 are the first.
It has the same function as that described in the embodiment.

The exciter voltage comparator 8 is a comparator for comparing the signal transmitted from the vibration oscillator 1 with a preset voltage level. The signal transmitted from the vibration oscillator 1 is binarized and converted into a signal represented by a digital level. The reference signal a is output. The detection signal voltage comparator 9 is a comparator for comparing the signal detected by the vibration detector 3 with a preset voltage level, and binarizes the signal detected by the vibration detector 3 to convert it into a signal represented by a digital level. And outputs the compared signal b.

Here, the exciter voltage comparator and the detection signal voltage comparator (comparator) in the second embodiment of the present invention will be described in detail with reference to FIG. In FIG. 7, U1 is an operational amplifier or an IC dedicated to a comparator, a capacitor C1 is a capacitor for cutting a DC component from the vibration oscillator 1 or the vibration detector 3, and an electrolytic capacitor of about several tens of μF is suitable. R1 and R2 are resistors that determine the DC offset of the input signal with the DC component cut off. If R1 and R2 are selected to be the same value, the amplitude of the input signal will be set centered on the voltage value of 1/2 of the power supply voltage + V. . R3 and R4 are resistors for setting the comparison voltage of the comparator, and if R1, R2, R3, and R4 are selected to have the same value, it can be set to perform the voltage comparison at the center of the voltage level of the input signal. R5 is a feedback resistor for giving a hysteresis characteristic to the operation of the comparator.

Next, with reference to the timing chart of FIG. 8, detection of a pulse wave by phase comparison in the second embodiment of the present invention will be described. The waveforms of the reference signal a and the comparison signal b, which are the outputs of the exciter voltage comparator 8 and the detection signal voltage comparator 9, respectively, are binarized into digital signals as shown in FIG. The rising edges of a and the comparison signal b are clear. Therefore, it is clearly understood that the voltage of the phase difference signal p changes depending on whether the rising edge of the comparison signal b is in the advanced phase or the delayed phase with respect to the rising edge of the reference signal a, and the speed thereof. By removing the high frequency component of the phase difference signal p with the low pass filter 6, a pulse wave signal m as shown in FIG. 8 is obtained. By thus binarizing the reference signal a and the comparison signal b, the phase comparator 4 can operate stably.

As described above, according to the second embodiment of the present invention, in addition to the effect described in the first embodiment, the reference signal a and the comparison signal b are binarized into a digital signal. By doing so, there is an effect that the phase detection capability of the phase comparator 4 can be improved.

Next, a pulse wave monitor according to the third embodiment of the present invention will be described with reference to FIGS. 9 and 10. FIG. 9 is a block diagram showing the configuration of a pulse wave monitor according to the third embodiment of the present invention, and FIG. 10 is a block diagram showing the configuration of another pulse wave monitor according to the third embodiment of the present invention. In FIG. 9, a vibration oscillator 1, an exciter 2, a vibration detector 3, a phase comparator 4, a phase difference voltage converter 5, a low pass filter 6, a pulse wave waveform display means 7, an exciter voltage comparator 8 and a detection signal voltage. The comparator 9 has the same function as that described in the first and second embodiments.

In FIG. 9, the A / D converter 10 A / D converts the pulse wave signal from the low pass filter 6. The waveform memory 11 stores A / D converted pulse wave signal data. The D / A converter 12 D / A converts the pulse wave signal data stored in the waveform memory 11. Then, the pulse wave waveform display means 7 displays the D / A converted pulse wave signal data and the output of the low-pass filter 6 as a pulse wave signal. In this way, the waveform stored in the waveform memory 11 can be arbitrarily displayed. The processor 13 is an A / D converter 10,
The waveform memory 11 and the D / A converter 12 are controlled.

In FIG. 10, the blood pressure measuring means 14 measures the maximum blood pressure and the minimum blood pressure using a cuff (not shown). The continuous blood pressure calculating means 15 converts the pulse wave waveform detected by the phase comparison into a continuous blood pressure waveform by calibrating the pulse wave waveform with the systolic blood pressure and the diastolic blood pressure measured by the blood pressure measuring means 14. The blood pressure measuring means 14 may be the same device as the processor 13. Further, the continuous blood pressure waveform display means 16 displays the continuous blood pressure waveform output from the continuous blood pressure calculation means 15. The continuous blood pressure waveform display means 16 may be the same device as the pulse wave waveform display means 7.

As described above, according to the third embodiment of the present invention, in addition to the effects described in the first and second embodiments, the measured pulse wave waveform is stored in the memory. It is possible to display the stored waveform arbitrarily. Further, by calibrating the pulse wave waveform detected by the phase comparison with the systolic blood pressure and the diastolic blood pressure, there is an effect that a continuous blood pressure waveform can be measured without using a catheter.

[0036]

The present invention is configured as described above, and in particular, it is easy to attach the exciter and the vibration detector with double-sided tape or the like, and only detects the phase difference between the reference signal and the comparison signal. The A / D signal detected by the vibration detector.
Since there is no need to perform conversion or processor calculation, the pulse wave signal can be detected and displayed without delay with the minimum component configuration, and at the same time, the elastic properties of blood vessels can be measured. Thus, it is possible to provide a pulse wave monitor having an excellent effect that it can be used for diagnosis of the progress of arteriosclerosis.

Further, the present invention has an effect that the measured pulse wave waveform is stored in the memory, so that the stored waveform can be arbitrarily redisplayed, and the calibration is performed at the systolic blood pressure and the diastolic blood pressure. By doing
It is possible to provide a pulse wave monitor having an excellent effect that a continuous blood pressure waveform can be measured without using a catheter.

[Brief description of drawings]

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

FIG. 2 is a diagram showing a state where the exciter and the vibration detector according to the first embodiment of the present invention are attached to a living body;

FIG. 3 is a diagram for explaining the principle of pulse wave measurement according to the present invention;

FIG. 4 is a diagram for explaining pulse wave detection by phase comparison according to the present invention;

FIG. 5 is a timing chart illustrating detection of a pulse wave signal by phase comparison according to the first embodiment of the present invention,

FIG. 6 is a block diagram showing a configuration of a pulse wave monitor according to a second embodiment of the present invention,

FIG. 7 is a circuit diagram showing in detail a voltage comparator according to a second embodiment of the present invention,

FIG. 8 is a timing chart illustrating detection of a pulse wave by phase comparison according to the second embodiment of the present invention,

FIG. 9 is a block diagram showing a configuration of a pulse wave monitor according to a third embodiment of the present invention,

FIG. 10 is a block diagram showing the configuration of another pulse wave monitor according to the third embodiment of the present invention.

[Explanation of symbols]

1 Vibration oscillator 2 exciter 3 Vibration detector 4 Phase comparator 5 Phase difference voltage converter 6 low pass filter 7 Pulse wave waveform display means 8 Exciter voltage comparator 9 Detection signal voltage comparator 10 A / D converter 11 Waveform memory 12 D / A converter 13 processors 14 Blood Pressure Measuring Means 15 Continuous blood pressure calculation means 16 Continuous blood pressure waveform table means 20 Attachment means 21 wrist 22 radial artery 23 Vibration waveform propagating in artery a Reference signal b Comparison signal p Phase difference signal m pulse wave signal x, y Phase comparator output signal C capacitor R, R1, R2, R3, R4, R5 resistors Q1, Q2 FET C1 capacitor U1 comparator

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-11-318839 (JP, A) JP-A-11-226011 (JP, A) JP-B 57-5538 (JP, B2) JP-A 9- 506024 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) A61B 5/02-5/03 A61B 8/00-8/12

Claims (4)

(57) [Claims] 1. An oscillator that oscillates a signal at an arbitrary frequency and amplitude, an exciter that oscillates an artery in the living body by the oscillation signal of the oscillator, a sticking means that sticks the exciter to the living body, and A vibration detector that converts the propagated vibration from the exciter into an electric signal, a sticking unit that sticks the vibration detector to a living body, a signal oscillated by the oscillator, and an electric signal converted by the vibration detector. , A phase comparator for detecting the phase difference, a phase difference voltage converter for converting the output of the phase comparator into a voltage indicating the phase difference, and a low-frequency component of the output signal from the phase difference voltage converter. A pulse wave monitor comprising: a low-pass filter for outputting a pulse wave signal according to claim 1, and a pulse wave waveform display means for displaying the pulse wave signal output from the low pass filter. 2. An exciter voltage comparator for comparing an oscillation signal from the oscillator with a preset voltage level and outputting a comparison result, and an electric signal converted by the vibration detector with a preset voltage level. A detection signal voltage comparator for comparing and outputting a comparison result, wherein the phase comparator detects a phase difference between the output signal from the exciter voltage comparator and the output signal from the detection signal voltage comparator. The pulse wave monitor according to claim 1, wherein: 3. An A / D converter for A / D converting the pulse wave signal output from the low pass filter into a digital signal,
A waveform memory for storing the A / D converted digital signal; a D / A converter for D / A converting the digital signal stored in the waveform memory into a pulse wave signal;
A / A converted pulse wave signal and pulse wave waveform display means for displaying the pulse wave signal output from the low-pass filter;
The pulse wave monitor according to claim 1 or 2, further comprising a / D converter, a D / A converter, and a processor that controls a waveform memory. 4. A blood pressure measuring means for measuring a systolic blood pressure and a diastolic blood pressure, a blood pressure calculating means for converting the A / D converted pulse wave signal into a continuous blood pressure waveform, and a continuous blood pressure calculated by the blood pressure calculating means. The pulse wave monitor according to claim 3, further comprising a continuous blood pressure waveform display means for displaying a waveform.