JPH11347008A - Induced electric potential measuring device and storage medium storing induced electric potential measuring program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten the period of examination, to reduce burden on a subject, and to obtain highly reliable data from the examination. SOLUTION: This induced electric potential measuring device to be disclosed here has a stimulation signal outputting means 2, a display means 7, a period producing means 8, an operation means 9, a standard voltage outputting means 10, and a prediction means 11. When such preparations are made for measuring nervous action electric potential generated by the nerves, the brain, and the muscles of a subject 12, as attaching biological electrodes 14a-14c to the body of the subject 12 or arranging cables 13a-13c to be pulled around, etc., stimulations are applied to the subject 12 with the preparations maintained in the condition, and nervous action electric potential of the subject 12 is measured. Whether the result of the measurement is good or bad is predicted by the prediction means 11 based on the voltage generated at the biological electrodes 14b and 14c without applying stimulations to the subject 12 by the stimulation signal outputting means 2, and the result of the prediction is displayed on the display means 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an evoked potential measuring device and a storage medium storing an evoked potential measuring program, and more particularly, to applying a minute current to a living body as a subject for a short time, showing light for a short time, The evoked potential measurement device and evoked potential measurement program that measure the action potential (nerve action potential) generated by nerves, brains and muscles by stimulating the nerves, brain and muscles of the living body by listening to time sounds It relates to the stored storage medium.

[0002]

2. Description of the Related Art Nerve action potentials generated by nerves, brains, and muscles of a living body in response to a stimulus applied by an evoked potential measuring device are extremely small, so that parts other than nerves, brains, and muscles to be examined are generated. The noise (external noise) generated by the nerve action potential or electrical equipment other than the fluorescent lamp and the evoked potential measuring device may be larger. Therefore, conventionally, the following measures have been taken in order to obtain a desired nerve action potential. First, in order to eliminate the effects of nerve action potentials generated by parts other than the nerve, brain and muscle to be examined, apply periodic stimulation to the nerve, brain and muscle to be examined and synchronize them with the cycle. Only the obtained nerve action potentials were added and averaged based on the averaging method. This averaging method utilizes the fact that when signal components and noise components are mixed, the signal components become clear by addition. A signal obtained by adding k times, where S is the nerve action potential of the nerve, brain, or muscle to be examined, and N is the amplitude of a random noise component such as a nerve action potential generated by a part other than the nerve, brain, or muscle to be examined. While the component is kS, the noise component added k times is averaged to be √k · N. Therefore, as the number of additions k increases, the noise components cancel each other out, and the addition result approaches zero, so that only the addition result of the nerve action potential of the nerve, brain or muscle to be examined is obtained.

[0003] Next, as a main factor in which external noise is mixed into the evoked potential measuring device, an electrode to be attached to the subject's living body to extract a desired nerve action potential from the subject's living body, and an evoked potential measuring device are constituted. It is conceivable that the resistance between the amplifying means for amplifying the nerve action potential to be applied is large. Therefore, in order to reduce the right resistance, only the fluorescent lamp required for the inspection is turned on, the power of other electrical equipment is turned off, and for electrical equipment that can not be turned off, the evoked potential measurement device can I was moving away. In addition, the method of attaching the electrode to a living body of a subject and the routing of a cable connecting the electrode and the evoked potential measuring device have been devised. Various measures were taken to reduce the resistance value displayed on the display means constituting the evoked potential measurement device, and it was predicted whether a good test result could be obtained.

[0004]

However, the above-mentioned conventional evoked potential measuring apparatus has the following drawbacks. If periodic stimulation is applied to the nerve, brain or muscle to be examined, and only the nerve action potentials obtained in synchronization with the cycle are added and averaged, other parts that are changing irregularly are sure. The generated nerve action potential and external noise can be removed, but periodic noise cannot be sufficiently removed. In addition, the noise that is electromagnetically coupled to the cable connecting the electrode attached to the living body of the subject and the amplifying means of the evoked potential measuring device has a causal relationship with the resistance value between the electrode and the amplifying means. Since there is not much, even if the above-described various measures are taken to lower the resistance value, the noise is not always reduced. Therefore, the resistance value does not sufficiently serve as a parameter for predicting whether or not a good inspection result is obtained.

In the end, it is impossible to use the result obtained due to the strong influence of the periodic noise and the external noise, that is, it cannot be said that the data is reliable. After applying the stimulus. Although it depends on the test object, it is usually after adding the obtained values of the nerve action potential several hundred times. For example, in the auditory brainstem response test and the function test of the auditory nervous system, a short sound is
The value of the nerve action potential obtained by listening to the subject in the cycle of z is added about 1000 times. In this case, it takes about 100 seconds to obtain the inspection result. Therefore, when the test result is unusable, the test must be performed taking about 100 seconds more, which takes time and burdens on the subject, particularly the effect on the living body.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and can reduce an examination time, reduce a burden on a subject, and obtain highly reliable data. It is intended to provide a storage medium storing a measurement program.

[0007]

In order to solve the above-mentioned problems, the invention according to claim 1 is to provide an evoked potential for measuring a nerve action potential generated by a nerve, brain or muscle of the subject by applying a stimulus to the subject. According to the measuring device, in a state where the preparation for measuring the nerve action potential is completed, without applying a stimulus to the subject, the stimulus is applied to the subject while maintaining the state based on the voltage generated at the electrode. The present invention is characterized in that it comprises a predicting means for predicting and notifying the quality of the measurement result obtained as described above. In the present invention, the state in which the preparation for measuring the nerve action potential is completed includes, for example, a state in which the electrode is completely attached to the living body of the subject, and a cable connecting the electrode with the evoked potential measurement device. This is a state in which routing has been completed.

According to a second aspect of the present invention, there is provided the apparatus for measuring an evoked potential according to the first aspect, wherein the predicting means determines a difference between a maximum value and a minimum value of the voltage, an effective value of the voltage, or a value of the voltage. The method is characterized in that the quality of the measurement result is predicted based on the maximum value of the absolute value and the nerve action potential measured in advance for each type of test in a measurement environment in which noise can be ignored.

According to a third aspect of the present invention, there is provided a trigger for processing and displaying a nerve action potential generated by a subject's nerve, brain or muscle by applying a stimulus to the subject at predetermined intervals, based on an averaging method. According to a potential measurement device, based on a voltage generated at the electrode without applying a stimulus to the subject in a state where preparation for measuring the nerve action potential is completed, applying a stimulus to the subject while maintaining the state. And a prediction means for predicting and displaying the quality of the measurement result obtained by the method.

According to a fourth aspect of the present invention, there is provided the evoked potential measuring device according to the third aspect, wherein the predicting means includes a difference between a maximum value and a minimum value of the voltage, an effective value of the voltage, or a value of the voltage. Based on the maximum value of the absolute value and the difference between the maximum value and the minimum value, the effective value, or the maximum value of the absolute value of the nerve action potential previously measured for each type of test in a measurement environment where noise can be ignored. The predetermined S of the neural action potential obtained by stimulating the subject while maintaining the above state
It is characterized in that the number of times to be added is calculated by the averaging method in order to obtain the N ratio.

According to a fifth aspect of the present invention, there is provided the evoked potential measuring device according to the third or fourth aspect, wherein the electroencephalogram, pulse,
Alternatively, it is characterized by comprising: detecting means for detecting at least one of respiratory cycles; and cycle setting means for setting a cycle for applying a stimulus to the subject based on a detection result of the detecting means.

According to a sixth aspect of the present invention, there is provided the apparatus for measuring an evoked potential according to any one of the third to fifth aspects, wherein the subject has at least one of coughing, sneezing, body shaking, or body movement. And detecting the detection timing of the detecting means together with the processing result based on the averaging method.

According to a seventh aspect of the present invention, there is provided the apparatus for measuring an evoked potential according to any one of the third to fifth aspects, wherein the subject has at least one of coughing, sneezing, body shaking, and body movement. And detecting a result of masking only the nerve action potential corresponding to the detection timing of the detecting means based on the averaging method.

The storage medium according to the invention of claim 8 is characterized in that an evoked potential measurement program for causing a computer to realize the function of any one of claims 1 to 7 is stored. I have.

[0015]

According to the structure of the present invention, before the stimulus is applied to the subject, the prediction means predicts the quality of the measurement result and informs the user of the result. Therefore, it is not necessary to repeat the measurement, so that the examination time can be shortened and the burden on the subject can be reduced. And highly reliable data can be obtained.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. The description will be specifically made using an embodiment. FIG. 1 is a block diagram showing an electric configuration of an evoked potential measuring device according to one embodiment of the present invention.
Is a flowchart showing the operation of the voltage difference calculating means constituting the evoked potential measuring device, and FIG. 3 is a diagram showing an example of the waveform of a signal output from each part of the evoked potential measuring device. As shown in FIG. 1, the evoked potential measuring device of this example includes period generating means 1 and 8, stimulus signal outputting means 2, amplifying means 3, digitizing and storing means 4, arithmetic means 5,
9, a feature extraction unit 6, a display unit 7, a standard voltage output unit 10, and a prediction unit 11.
The cycle generation means 1 generates a measurement cycle signal ST having a predetermined cycle based on depression of a measurement start switch (not shown) for instructing the start of measurement, and outputs a stimulus signal output means 2 and a digitization / storage means. 4 The stimulus signal output means 2 outputs the measurement cycle signal ST supplied from the cycle generation means 1.
In synchronism with the above, a weak stimulus signal SS for giving a sensory stimulus to the subject 12 is generated, and the cable 13a and the bioelectrode 14 attached to, for example, the left wrist of the subject 12 are generated.
The stimulus signal SS is applied to the subject 12 via a.

The amplifying means 3 is provided, for example, for the subject 12
Bioelectrode 14b and bioelectrode 14c attached to the head
And amplifies the weak nerve action potential supplied via cables 13b and 13c with high sensitivity,
Filtering is performed to remove noise in a frequency band other than the frequency band where the nerve action potential exists. The ground terminal (not shown) of the amplification means 3 is connected to the ground cable 1.
For example, it is connected to an earth band 16 made of a conductor attached to the left arm of the subject 12 through the fifth arm 5. The digitizing / storage means 4 has a sampling circuit, an A / D converter, and a memory, and synchronizes with the measurement period signal ST supplied from the period generation unit 1 and outputs analog neural activity output from the amplification unit 3. After the potential is sampled at a predetermined sampling frequency, it is converted (quantized) into a digital nerve action potential and stored in a memory. The calculating means 5 reads out the digital nerve action potential stored in the memory constituting the digitizing and storing means 4, performs an adding process and an averaging process based on an averaging method, and outputs the calculated result to a CRT display. And a display means 7 comprising a liquid crystal display or the like. The feature extracting means 6 reads out the digital nerve action potential stored in the memory constituting the digitizing / storage means 4, extracts features such as the amplitude of the average peak, and displays the extracted result on the display means 7. indicate. Period generation means 8
Generates a confirmation cycle signal SK (see FIG. 3A) of a predetermined cycle T based on depression of a confirmation switch (not shown) for confirming whether or not measurement can be started. To the means 9. The calculating means 9 has a sampling circuit and an A / D converter, and outputs from the amplifying means 3 in a state where the stimulus signal SS is not applied to the subject 12 in synchronization with the confirmation cycle signal SK supplied from the cycle generating means 8. The sampled analog signal SA (see FIG. 3B) is sampled at the same sampling frequency as the sampling frequency used by the A / D converter constituting the digitizing / storage means 4 and then converted into a digital signal ( Quantization), and furthermore, the maximum value Vmax and the minimum value Vm of the analog signal SA in one cycle of the confirmation cycle signal SK.
The maximum value VDmax and the minimum value VDmin of the digital signal corresponding to “in” (see FIG. 3B) are obtained, and the voltage difference VDD is calculated and supplied to the prediction unit 11.

The standard voltage output means 10 is provided with an inspection code input key (not shown) for inputting a preset code corresponding to the inspection in order to set what kind of inspection is to be performed. Based on the press, the standard voltage VS corresponding to the inspection code is output and supplied to the prediction unit 11. Since the level of the nerve action potential obtained from the living body of the subject 12 varies depending on the type of the test, the standard voltage VS to be compared also varies accordingly. Therefore, the standard voltage output means 10 outputs the standard voltage V corresponding to the input inspection code.
It outputs S. This standard voltage output means 10
For example, the standard voltage VS is stored in advance for each inspection code in a storage device such as a semiconductor memory, or an arithmetic expression for obtaining the standard voltage VS preset for each inspection code is stored. Standard voltage VS corresponding to code
May be configured by an arithmetic unit that obtains based on an arithmetic expression corresponding thereto. Here, the standard voltage VS means, for each type of examination, neural activity obtained when a healthy subject is examined under an ideal measurement environment in which noise input to the amplification means 3 can be ignored. Refers to potential.

The predicting means 11 receives the supplied voltage difference VDD.
Based on the standard voltage VS and the standard voltage VS, the number of additions until a highly reliable addition / average result of the nerve action potential is obtained is calculated and displayed on the display means 7. Here, a method of deriving the number of additions will be described. As described in the background art, in the averaging method, if the amplitude of a signal component is S and the amplitude of a random noise component is N, the signal component added k times becomes kS, whereas the signal component added k times becomes kS. The obtained noise components are averaged to become √k · N. That is, the SN ratio after addition k times (hereinafter referred to as SNk) is improved by Δk from the SN ratio before addition (hereinafter simply referred to as SN). First, since the voltage output from the amplifying unit 3 in a state where the stimulus signal SS is not applied to the subject 12 has almost all noise components, it is assumed that all of the voltages are noise components. In this example, the voltage difference VDD is used as a noise component. On the other hand, for each type of inspection,
Under an ideal measurement environment in which noise inputted to the amplification means 3 can be ignored, a nerve action potential obtained when a healthy subject is examined is obtained in advance, and this is the standard voltage VS. Therefore, SN becomes VDD / VS. By the way, when the nerve action potential, that is, the signal component waveform is displayed on the display means 7, the SN ratio which can be confirmed to be superior to the noise component is usually 10 to 100 (20 to 100).
40 dB). This S / N ratio is the S / N ratio after k additions by the averaging method, that is, SN k. Therefore, the relationship between SN and SNk is expressed by equation (1), and SN is VDD / VS, so the number of additions k is expressed by equation (2). In the equation (2), Int (VS /
(VDD) means an integer part of a value obtained by dividing VS by VDD. Because the number of additions k must be an integer

[0020]

## EQU1 ## SNk = √k · SN (1)

[0021]

K = (SNk · Int (VS / VDD)) ² (2)

For example, assuming that the value of the nerve action potential obtained in the function test of the auditory nervous system is about 0.6 μV, the amplitude of the noise component is about 2 μV, and the desired SNk is 10 (20 dB), the number of additions k is From equation (2), the number of times is 1089. This number of additions substantially coincides with the number of additions generally performed. Therefore, before the stimulus is applied to the subject 1 and the nerve action potential is measured, the number of additions k in the pasting of the current bioelectrodes 14a to 14c and other preparation states is obtained based on the equation (2) and displayed on the display means 7. The display allows the measurer to determine whether the current preparation state is good or not, and in some cases, changes the pasting state of the bioelectrodes 14a to 14c and other preparation states. Here, the number of additions includes the number of times that is generally performed for each type of test. For example, in the above-described function test of the auditory nervous system, 1000 to 2
000 times, and 100 to 200 times in case of somatosensory. Therefore, for each type of inspection, the number of additions generally performed and the SN ratio obtained in this case are calculated by the prediction unit 1.
1 may be stored in advance in the memory of the display unit 1 and displayed on the display unit 7 together with the number of additions k obtained by the above calculation.

Next, the operation of the evoked potential measuring device having the above configuration will be described with reference to FIGS. First,
As shown in FIG. 1, after the measurer attaches the bioelectrodes 14 a to 14 c and attaches the earth band 16 to the head and left arm of the subject 1 and routes the cables 13 a to 13 c and the earth cable 15, A code corresponding to the type of inspection is input using an inspection code input key (not shown), and a confirmation switch (not shown) is pressed. As a result, the amplifying unit 3 provides the subject 12 with the stimulus signal SS from the biological electrode 14a.
Is applied between the bioelectrode 14b and the bioelectrode 14c in a state where no voltage is applied, the weak potential supplied through the cables 13b and 13c is amplified, and only the potential in a predetermined frequency band is converted to an analog signal SA (FIG. 3). (See (b)) and supplies it to the calculating means 9. On the other hand, the cycle generation means 8
Generates a confirmation cycle signal SK (see FIG. 3A) of a predetermined cycle T based on the depression of a confirmation switch (not shown) and supplies the signal to the arithmetic means 9.

Therefore, the calculating means 9 performs a process of calculating the voltage difference VDD according to the flowchart shown in FIG.
The calculating means 9 outputs the analog signal S every time the following operation is performed.
A sampling process and a quantization process of A are performed, but for the sake of simplicity, description will be made on the assumption that these processes have been completed. First, the arithmetic unit 9 proceeds to the processing of step SP1 and checks the confirmation cycle signal SK supplied from the cycle generation unit 8.
Signal S obtained in synchronization with the first rising edge of
After the voltage value VDst of the digital signal corresponding to the voltage value Vst of A (see FIG. 3B) is stored in the maximum value register as the maximum value VDmax, the process proceeds to step SP2. Step S
At P2, the voltage value VDst is stored in the minimum value register as the minimum value VDmin, and the process proceeds to step SP3. In step SP3, after the voltage value VD sampled next to the voltage value VDst is stored in the current value register by the sampling process, the process proceeds to step SP4. In step SP4, it is determined whether or not the value of the voltage value VD stored in the current value register is larger than the maximum value VDmax stored in the maximum value register. If this determination is "YES", the flow proceeds to step SP5. In step SP5, after the voltage value VD stored in the current value register is stored in the maximum value register as a new maximum value VDmax, the process proceeds to step SP6.
On the other hand, if the result of the determination in step SP4 is "NO", that is, if the value of the voltage value VD stored in the current value register is equal to or less than the maximum value VDmax stored in the maximum value register, the process also proceeds to step SP6.

At step SP6, it is determined whether or not the value of the voltage value VD stored in the current value register is smaller than the minimum value VDmin stored in the minimum value register. If the result of this determination is "YES", the flow proceeds to step SP7. In step SP7, after the voltage value VD stored in the current value register is stored in the minimum value register as a new minimum value VDmin, the process proceeds to step SP8. On the other hand, if the determination result in step SP6 is "NO", that is, if the value of the voltage value VD stored in the current value register is equal to or greater than the minimum value VDmin stored in the minimum value register, the process also proceeds to step SP8. In step SP8, the check period signal S
It is determined whether the cycle T of K has elapsed. If the result of this determination is "NO", the process returns to step SP3 and repeats the processing of steps SP3 to SP7 described above. Then, when the cycle T of the confirmation cycle signal SK elapses, step S
The result of the determination at P8 is "YES", and the routine proceeds to step SP9. In step SP9, by subtracting the minimum value VDmin stored in the minimum value register from the maximum value VDmax stored in the maximum value register, the voltage difference VDD is calculated and stored in the voltage difference register, and then the process returns to step SP3. , The maximum value VD of the confirmation cycle signal SK in the next cycle T
The detection of the max and the minimum value VDmin and the calculation of the voltage difference VDD are repeated. The calculation means 9 repeats the above-described processing, for example, until the confirmation switch (not shown) is pressed again, then reads out the voltage difference VDD stored in the voltage difference register and supplies it to the prediction means 11. In this case, the calculating means 9 may be configured to read the voltage difference VDD stored in the voltage difference register and supply the voltage difference VDD to the prediction means 11 in synchronization with the rise of the next cycle T of the confirmation cycle signal SK. .

The predicting means 11 substitutes the voltage difference VDD supplied from the calculating means 9 and the standard voltage VS supplied from the standard voltage output means 10 into equation (2) to calculate the number of additions k, It is displayed on the display means 7. In this case, as for SNk, for example, the operator inputs a desired value out of 10 to 100 using the numeric keypad, and substitutes the input value into equation (2) to calculate the number of additions k. Alternatively, the prediction means 11 may calculate the number of additions k for each value by substituting it into the equation (2) in increments of 10, for example, and display the result on the display means 7. good. When the voltage difference VDD is supplied from the calculating means 9 in synchronization with the rise of each cycle T of the confirmation cycle signal SK, the number of additions k is calculated and displayed on the display means 7 each time. If the number of additions generally performed and the S / N ratio obtained in this case are stored in advance in the memory in the prediction means 11 for each type of inspection, the number of additions k
Is displayed on the display means 7. This allows the measurer to
The number of additions k at which a desired SNk can be obtained in the current preparation state can be known, and the difference from the number of additions that is generally performed can be grasped, so that the quality of the current preparation state can be determined.

When it is determined that the preparation state is good, the measurer depresses a measurement start switch (not shown) to cause the evoked potential measuring device to measure a desired nerve action potential and display it on the display means 7. . Period generating means 1 of the evoked potential measuring device
Generates a measurement period signal ST based on the depression of a measurement start switch (not shown) and supplies it to the stimulus signal output means 2 and the digitization / storage means 4. Thereby, the stimulus signal output unit 2 generates the stimulus signal SS corresponding to the type of examination in synchronization with the measurement period signal ST supplied from the period generation unit 1, and outputs the stimulus signal SS via the cable 13a and the biological electrode 14a. Apply to subject 12. Amplifying means 3 includes subject 1
2 and the bioelectrode 1 attached to the head of
4c, and amplifies the nerve action potential supplied through the cables 13b and 13c, passes only the nerve action potential in a predetermined frequency band, and supplies it to the digitizing and storage means 4. The digitizing / storage means 4 synchronizes with the measurement cycle signal ST supplied from the cycle generation means 1,
After the analog nerve action potential output from the amplifying means 3 is sampled at a predetermined sampling frequency, it is converted (quantized) into a digital nerve action potential and stored in an internal memory. The calculating means 5 reads out the digital nerve action potential stored in the memory inside the digitizing / storage means 4,
Perform addition processing and averaging processing based on the averaging method,
The calculation result is displayed on the display means 7. On the other hand, the feature extracting means 6 reads out the digital nerve action potential stored in the memory inside the digitizing / storage means 4, extracts features such as the amplitude of the average peak, and displays the extraction result. 7 is displayed.

On the other hand, if it is determined that the current preparation state is not good, the measurer changes the position where the bioelectrodes 14a to 14c are attached to the subject 12 or the position where the earth band 16 is attached to the subject 12, or the cables 13a to 13c. The route of the ground cable 13c or the ground cable 15 is changed, or a fluorescent lamp unnecessary for the inspection is turned off, the power of another electric device is turned off, and an electric device that cannot be turned off is moved away. And
The measurer presses the confirmation switch (not shown) again to cause the evoked potential measuring device to perform the above operation, and determines the quality of the preparation state. If it is determined that the preparation state is good, the measurer presses a measurement start switch (not shown) to cause the evoked potential measuring device to measure a desired nerve action potential, and the display means 7
To be displayed. The period generating means 1, the stimulus signal outputting means 2, the amplifying means 3, the digitizing / storing means 4, the calculating means 5 and the feature extracting means 6 of the evoked potential measuring device perform the same operations as described above, and the display means 7 The waveform of the measured nerve action potential and others are displayed.

As described above, according to the configuration of this example, the biological electrode 1 is applied to the subject 12 in a state ready for measurement.
Since the number of additions k can be predicted without applying the stimulus signal SS from 4a, the measurement time can be reduced and the burden on the subject can be reduced. At the preparation stage of the measurement, the influence of noise is reduced as much as possible, so that the reliability of the obtained result is improved.

The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and changes in design and the like can be made without departing from the gist of the present invention. Even if there is, it is included in the present invention. For example, in the above-described embodiment, an example in which a minute current is applied to a living body as a subject in a short time is shown.However, the present invention is not limited to this. Any object may be used as long as it stimulates the nerves, brain and muscles of the living body. Further, in the above-described embodiment, although the reduction of the periodic noise is not particularly described, for the periodic noise related to the electroencephalogram and the pulse of the subject 12, for example, a sensor that can detect the electroencephalogram and the pulse wave, A sensor capable of detecting the respiratory cycle is attached to the living body of the subject 12, and based on the output signals of each sensor, a measurement cycle signal ST at a timing such that there is no effect of brain waves, pulses, or respiration.
May be generated by the cycle generation means 1.
Also, it detects the subject 12 coughing or sneezing, shaking of the body, or detecting that the subject 12 moves his / her body during the measurement although it cannot be said that it is periodic, and displays the detection timing together with the waveform of the nerve action potential and the like. May be displayed. With this configuration, it is not possible to remove noise related to cough and the like from the nerve action potential waveform itself, but it is possible to point out where the influence is, so the measurer considers that point when judging the measurement result. can do. Further, in order to remove noise itself related to cough or the like from the waveform of the nerve action potential, the amplification means 3 may be configured to mask only a portion of the nerve action potential corresponding to the detection timing.

Further, in the above embodiment, the calculating means 9 calculates the maximum value Vmax and the minimum value Vmin of the analog signal SA.
The maximum value VDmax and the minimum value V of the digital signal corresponding to
Although the example in which Dmin is obtained and the voltage difference VDD is calculated is shown, the present invention is not limited to this, and the maximum value of the effective value or the absolute value of the digital signal corresponding to the maximum value of the effective value or the absolute value of the analog signal SA is calculated. You may comprise so that it may calculate. in this case,
For each type of test, it corresponds to the maximum value of the effective value and the absolute value obtained when a healthy subject is tested under an ideal measurement environment in which the noise input to the amplification means 3 can be ignored. Standard voltage output means 1 for maximum value of effective value and absolute value
0 is supplied to the prediction means 11. Accordingly, the prediction unit 11 calculates the number of additions k based on the same equation as the above-described equation (2), and displays the number of additions on the display unit 7 together with SNk, the number of additions generally performed, and the like.

Further, in the above-described embodiment, an example in which each means is constituted by hardware has been described, but the present invention is not limited to this. That is, the above evoked potential measuring device includes a CPU (central processing unit), an internal storage device such as a ROM and a RAM,
FDD (Floppy Disk Driver), HDD
(A hard disk driver), a computer having an external storage device such as a CD-ROM driver, an output unit, and an input unit. 6. Among the standard voltage output means 10 and the prediction means 11, the internal memory and the A / D converter other than the internal memory are constituted by a CPU, and as the evoked potential measurement program, semiconductor memory such as ROM, FD (floppy disk), HD (Hard disk) or a storage medium such as a CD-ROM. In this case, the evoked potential measurement program is read into the CPU from the storage medium, and controls the operation of the CPU. When the evoked potential measurement program is started, the CPU digitizes and stores the data, the calculation means 5, 9, the feature extraction means 6, the standard voltage output means 10, and the prediction means 1.
It functions as 1 and executes the above-described processing under the control of the evoked potential measurement program.

[0033]

As described above, according to the configuration of the present invention, before the stimulus is applied to the subject, the prediction means predicts the quality of the measurement result and informs the user. Can be reduced, the burden on the subject can be reduced, and highly reliable data can be obtained. Further, according to the configuration of the invention described in claims 5, 6, and 7, the influence of periodic noise can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an electrical configuration of an evoked potential measuring device according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating a flow of an operation of a calculation unit included in the evoked potential measuring device.

FIG. 3 is a waveform chart showing an example of a waveform of a signal output from each unit of the evoked potential measuring device.

[Explanation of symbols]

 2 stimulus signal output means 7 display means 8 cycle generation means (prediction means) 9 calculation means (prediction means) 10 standard voltage output means (prediction means) 11 prediction means 12 subjects 13a to 13c cables 14a to 14c bioelectrodes

Claims (8)

[Claims] Claims: 1. A stimulus is applied to a subject,
An evoked potential measuring device that measures a nerve action potential generated by a brain or a muscle, and in a state where preparation for measuring the nerve action potential is completed, without applying a stimulus to the subject, a voltage generated at the electrode is measured. An evoked potential measurement device, comprising: a prediction unit for predicting and reporting the quality of a measurement result obtained by applying a stimulus to the subject while maintaining the state. 2. The method according to claim 1, wherein the predicting unit determines a difference between a maximum value and a minimum value of the voltage, an effective value of the voltage, or a maximum value of an absolute value of the voltage and a type of the test under a measurement environment in which noise can be ignored. Based on the nerve action potential measured in advance for each
2. The evoked potential measuring device according to claim 1, wherein the quality of the measurement result is predicted. 3. An evoked potential measuring device which processes and displays a nerve action potential generated by a nerve, a brain or a muscle of a subject obtained by applying a stimulus to the subject at predetermined intervals based on an averaging method. A measurement result obtained by applying a stimulus to the subject while maintaining the state based on a voltage generated at the electrode without applying a stimulus to the subject in a state where preparation for measuring the nerve action potential is completed. An evoked potential measuring device comprising a predicting means for predicting and displaying the quality of a test. 4. The method according to claim 1, wherein the predicting means determines a difference between a maximum value and a minimum value of the voltage, an effective value of the voltage, or a maximum value of an absolute value of the voltage, and a type of the test under a measurement environment in which noise can be ignored. The neural action potential measured in advance for each, based on the difference between the maximum value and the minimum value, the effective value, or the maximum value of the absolute value, is obtained by applying a stimulus to the subject while maintaining the state. 4. The evoked potential measuring device according to claim 3, wherein the number of times to be added is calculated by the averaging method in order to obtain a predetermined SN ratio of the nerve action potential. 5. A detecting means for detecting at least one of the subject's brain waves, pulse, or respiratory cycle, and a cycle setting means for setting a cycle for applying a stimulus to the subject based on a detection result of the detecting means. The evoked potential measuring device according to claim 3 or 4, further comprising: 6. A detecting means for detecting at least one of the subject's cough, sneezing, body tremor, and body movement, and the detecting timing of the detecting means is based on the averaging method of the nerve action potential. The evoked potential measurement device according to claim 3, wherein the evoked potential measurement device is displayed together with a processing result. 7. A detecting means for detecting at least one of the subject's cough, sneezing, body tremor, or movement of the body, wherein only a portion of a nerve action potential corresponding to a detection timing of the detecting means is masked. 7. The evoked potential measuring device according to claim 3, wherein the result is processed based on an averaging method. 8. A storage medium storing an evoked potential measurement program for causing a computer to realize the function according to claim 1.