KR100379571B1 - Detecting device of brain signal using the digital brain wave and displaying method thereof - Google Patents

Abstract

The present invention relates to a brain function monitoring system, and the brain blood flow monitoring device using a digital brain wave to remove the noise interference from the operation of a plurality of medical equipment, so that accurate monitoring of the brain blood flow of the unconscious state patient in real time and the brain Disclosed is a method for displaying digital brain waves in a blood flow monitoring apparatus.

In order to monitor the brain ischemia, the present invention extends a single-channel EEG dipole amplifier to multiple channels to effectively remove noise generated from electromyostasis (ESU) or surgical electronic equipment, and to amplify the EEG signal 1000 times. Preamplifier; A main amplifier for performing power amplification and noise removal of a predetermined level or more on the noise passing through the preamplifier, and comprising a filter having a variable frequency band to obtain a desired frequency band; And a control unit for digitally reading the signals amplified by the preamplifier and the main amplification unit from a computer, and extracting and displaying various clinical brain wave parameters. It is easy to obtain an effect that can be comprehensively observed the patient when monitoring the surgical patient.

Description

TECHNICAL DEVICE OF BRAIN SIGNAL USING THE DIGITAL BRAIN WAVE AND DISPLAYING METHOD THEREOF}

The present invention relates to a brain function monitoring system, and more particularly to a brain function monitoring device using a digital brain wave for detecting cerebral ischemia so that accurate monitoring of the cerebral blood flow of an unconscious state patient is supported in real time. A display method of digital brain waves.

In general, cerebral stroke is the leading cause of sudden death syndrome, and many techniques have been developed to prevent it early. Examples are CT, MRI, SPECT using analogue Xenon isotope or analog EEG (Electroencephalogram), EP, etc. Most of the systems show only the brain blood flow status at the time of examination, so the reading of the results is only possible by trained EEG specialists. It is possible. Therefore, the hassle of having an EEG specialist should be resident during the observation period of the patient.

On the other hand, in recent years, the CSA (Compressed Spectral Array) applying the FFT (Fast Fourier Transform) by digitally converting the analog EEG has been developed, and it is possible to easily observe the change state of the brain blood flow even without an EEG specialist. Clinical applications such as coma and hypotension have begun.

Recently, researches on extracting EEG-related parameters by various signal processing of digital EEG have been introduced. Also, a method of analyzing EEG using raw signals and spectrums or using a topographic display technique has been presented in many channels. .

In particular, cerebral ischemia is detected through such EEG analysis during surgery. In order to prevent surgical bleeding, medical devices such as electric meat are generally used. When the electric meat is used, the high frequency current of the electric meat is introduced into the EEG amplifier by the path of the patient's body, and as the human body acts as an antenna, interference is generated from the high frequency signal generated from the electric meat. do.

Therefore, since the interference of the high frequency signal generated from the medical equipment such as electric meats causes a great adverse effect on the EEG monitoring, there is a problem that the efficiency of EEG monitoring is extremely reduced. Therefore, such a large number of EEG monitoring system is a system that enables only the collection and analysis of EEG data, or even using a two-channel EEG is a system that analyzes the activity of each frequency band of EEG but is not a real-time processing, eventually EEG monitoring can only be done empirically by skilled medical staff. This causes a problem of objectivity deterioration in the patient's status information, and the pure EEG detected in the above system is expressed in real time, but spectrum analysis is not supported in real time. The number of channels is too large to be used for the monitoring of cerebral ischemia during monitoring, and because it is an expensive system as a complicated structure, the medical equipment has not been popularized.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an EEG signal amplification circuit so that high frequency generated from an electrical medical device used in performing a surgical operation does not interfere with EEG signal amplification. At the same time, the amplified EEG signals are processed by software so that the brain function monitoring of the patient can be effectively performed, so that monitoring of changes in the brain blood flow and brain function monitoring of the unconscious patient can be supported in real time. The present invention provides a brain function monitoring device using a digital brain wave that enables early diagnosis and treatment, and a display method of digital brain waves in the brain function monitoring device.

The brain function monitoring apparatus using a digital brain wave according to the first aspect of the present invention for achieving the above object, by extending the single-channel brain wave dipole amplifier to multiple channels in order to monitor the cerebral ischemia phenomenon, the electromechanical (ESU) or surgery A preamplifier for effectively removing noise generated by electronic equipment and amplifying the EEG signal 1000 times; A main amplifier for performing power amplification and noise removal of a predetermined level or more on the noise passing through the preamplifier, and comprising a filter having a variable frequency band to obtain a desired frequency band; And a control unit for digitally reading out the signals amplified by the preamplifier and the main amplifier from a computer, and extracting and displaying various clinical EEG parameters.

Specifically, the preamplifier includes a filter for removing the artificial noise of the electric meat and a buffer having a high impedance; A differential amplifier to have a common mode rejection ratio even at a high frequency generated from the electric meat; A low frequency cut filter for removing direct current offset; A high frequency cut filter for removing high frequency noise; An amplifier for amplifying a frequency for brain wave measurement through the high frequency cutoff filter to a predetermined gain; And a separation amplifier for removing the high frequency digital switching noise included in the preamplifier and the power line and the ground of the preamplifier and the main amplifier in transmitting the amplified signal of the amplifier to the main amplifier.

The main amplifier includes a notch filter for removing noise introduced through the preamplifier; A low pass filter for removing noise generated by a signal transmission line in transmitting the signal from the preamplifier to the main amplifier; A DC offset removal filter for removing a DC signal among the EEG signals applied through the low pass filter; Notch filter to remove 60Hz power noise; A variable low pass filter for interfacing the EEG amplified signal with the control unit and variably limiting the signal band according to the sampling band of the computer; A variable high pass filter for variably limiting a direct current signal of the signal passing through the variable low pass filter; And a variable gain controller for amplifying the variable signal output by the variable high pass filter to a predetermined level.

In addition, in the brain function monitoring apparatus using the digital brain waves according to the second aspect of the present invention for achieving the above object is a digital brain wave display method of digitally processing the EEG signal of the patient amplified through the left and right channels, A first display process of displaying the pure EEG generated therefrom on a monitor; A second display process of extracting a spectrum of the digitized pure EEG signal through FFT and averaging and displaying the digitized pure EEG signal in a virtual three-dimensional manner; A third display process of displaying, on a screen, a DSA signal obtained by virtually three-dimensional processing the FFT spectrum power of the pure EEG signal in the form of a color band; A fourth display step of graphically processing and displaying total frequency power (TP) included in 1 kHz to 28 kHz of the left and right respective EEG signals; A fifth display step of displaying a spectral edge frequency (SEF) indicating a time point when the power of the pure EEG signal is accumulated from 1 kHz to 95% of the total frequency power (TP); A sixth display step of displaying an alpha ratio obtained by graphically processing a ratio between the frequency band power of α wave and the frequency band power of θ and δ wave of the EEG signal; A seventh display process of displaying a percentage delta obtained by graphically processing the percentage of power occupied by the δ wave in the entire frequency band; And an eighth display process of graphically processing a difference in total power (DTP) calculated from each of the left and right brain waves, and displaying CSA, DSA, TP, SEF, etc. of a patient state at a specific moment. And a screen capture function for displaying on the screen.

Specifically, by adding the digitized pure EEG data header (Header) to generate an EEG file containing the patient information and file information corresponding to the patient ID to enable the event marking and search (recording) of the record In addition, a ninth display process for managing the patient ID in the form of a hierarchical directory structure is added.

1 is a block diagram showing an EEG signal amplifier of the present invention.

FIG. 2 is a circuit diagram illustrating in detail the function of the preamplifier of FIG. 1.

3 is a circuit diagram additionally showing a noise canceling function of the present invention.

4 is a block diagram showing the main amplifier 103 in one embodiment.

5A and 5B are circuit diagrams illustrating FIG. 4.

FIG. 6 is a circuit diagram for generating a clock signal used in the variable low pass filter of FIG. 5A.

7 is a view for explaining the display structure of the present invention.

8A and 8B are diagrams for explaining data management of FIG.

9A-9E are signal waveforms showing brain wave parameters processed by software.

10 shows a screen display according to the execution of the software of the present invention.

<Description of the symbols for the main parts of the drawings>

101: preamplifier 103: main amplifier

105: control unit 301: current limiting circuit

401, LP1, LP2: Low pass filter 403: DC offset cancellation filter

407: notch filter 409: multiplexer

411 variable low pass filter 413 variable gain controller

601: pulse generator OP1-OP20: op amp

R1-R24: Resistor RR1-RR4: Array Resistor

C1-C20: Capacitor IC, IC1-IC8: IC

Hereinafter, with reference to the accompanying drawings showing an embodiment of the present invention.

1 is a block diagram showing an EEG signal amplifier of the present invention. FIG. 2 is a circuit diagram illustrating in detail the function of the preamplifier of FIG. 1. 3 is a circuit diagram showing a current limiting function added to the present invention. First, the comprehensive brain function monitoring apparatus, referring to FIG. 1, amplifies minute EEG signals introduced through a driving electrode and a reference electrode with high gain, and solves power line noise due to human induced current. A preamplifier 101 to remove the noise component of 60 Hz included in the amplified signal of the preamplifier 101, and a main amplifier 103 for converting the signal into a normal mode signal; The main amplifier 103 comprises a control unit 105 for controlling the system to obtain a predetermined amplification band.

On the other hand, the operation of the present invention according to the above configuration will be described.

The configuration is a multi-channel bipolar EEG amplifier, when introduced into the preamplifier 101 through a driving electrode and a reference electrode, to remove the noise caused by the inflow of an external signal, and then amplify the signal. Here, the amplification ratio may be about 1000 times as an example, and the amplified signal is transmitted to the main amplifier 103.

The main amplifier 103 allows the fine noise included in the amplified signal output from the preamplifier 101 to be removed through a filter and to obtain a predetermined frequency band through the variable frequency filter. Such a predetermined frequency band allows the user to selectively control the EEG signal included in the frequency band signal output from the preamplifier 101 or in the 60 Hz frequency band through a notch filter. .

Then, the analog signal output from the main amplifier 103 is converted into a digitized signal and applied to the control unit 105, and then the control unit 105 outputs the digitized control signal according to the change of the frequency band. . The digitized control signal is converted into an analog signal and applied to the main amplifier 103 to determine the amplification ratio of the main amplifier 103.

In one embodiment of the present invention, the amplification ratio of the main amplifier 103 is set from 1 to 100 times.

The preamplifier 101 will now be described in detail with reference to the accompanying drawings.

First, the preamplifier 101 of FIG. 2 is an artificial noise removing filter for removing artificial noise (artifa -cts) generated from a plurality of surgical equipment among the EEG signals introduced through the driving electrode and the reference electrode corresponding to two channels. (ESU: Artifacts Rejection Filter: 201), a buffer connected to each output electrode of the artificial noise rejection filter 201 for each electrode to minimize the influence from the electrode, and a buffer for each of the buffers ( Differential amplifier (205) for removing noise of the common component and amplifying only the differential component output from 203, and magnetic saturation due to DC deviation, that is, DC-offset in the differential amplifier 205 DC-offset Rejection Filter (207) to prevent the noise, and out of the frequencies passed through the DC Offset Rejection Filter (207), it is unnecessary to extract only the signal of the band suitable for EEG measurement. A high pass filter 209 for removing a high frequency signal, an amplifier 211 for amplifying a frequency for brain wave measurement through the high frequency cut filter 209 with a predetermined gain, and an amplifier 211. An isolation amplifier for removing high frequency digital switching noise flowing from a signal transmission line connected between the preamplifier 101 and the main amplifier 103 in transmitting the amplified signal to the main amplifier 103. 213).

Here, in the artificial noise removing filter 201, the same resistor R1 is connected to each electrode, and a capacitor C1 is connected between the resistors R1. The buffer 203 is composed of op amps OP1 and OP2 to invert the resistance of the artificial noise removing filter 201 to an input impedance, and the differential amplifier 205 is introduced from the buffer 203. The signal is differentially amplified through a resistor (R2) and an op amp (OP3), but the amplification gain is set based on the resistor (R3). In addition, the DC offset elimination filter 207 removes a specific frequency by the capacitor C2 and the resistor R4, and then outputs it through the resistor R6. The high frequency cutoff filter 209 is a frequency suitable for EEG measurement. Op amps for buffers OP4 for blocking only bands below the band, and resistors R7, capacitors C3 and C5, and resistors R8 connected to the input and feedback sides of the op amps OP4. ) And a capacitor C4 are connected to the output terminal of the op amp OP4.

In addition, the amplifier 211 is connected to the op amp (OP5) and the resistors (R9, R10) for setting the gain, the separate amplifier 213 is provided with an input resistor (R11) and IC (IC) main amplifier The signal applied to the unit 103 is made noise free. This is to ensure the safety of the patient during surgery by the separation of the patient and the power line, and to prevent the digital switching noise of the main amplifier 103 is introduced into the preamplifier 101.

Hereinafter, the operation of the preamplifier 101 according to the above configuration will be described.

First, many surgical instruments, including electric meat used in the operation of the patient has a frequency band of several hundred kHz to several MHz, and generates a voltage of several kV, artificial noise is involved in EEG monitoring. The artificial noise removal filter 201 passes through a driving electrode (RAE) and a reference electrode (RRE) (LRE) for detecting frequencies of the right and left brains near the brain of the patient. Is applied.

Artificial noise removing filter 201 is to remove the high frequency 300Hz or more that is induced to the human body from the electric meat. It passes only low frequency through two input resistors R1 and capacitor C1. In the present invention, the resistor R1 and capacitor C1 use 2.6 GHz and 0.1 GHz, respectively. The EEG signals flowing through the resistor R1 are respectively applied to non-inverting input terminals of the op amps OP1 and OP2 constituting the buffer 203. Such an input signal reduces the influence from the electrode having the source impedance. For op amps (OP1, OP2) with an input impedance of about 10 ¹¹ , and high common component rejection ratio, the effect of impedance change of the electrode is not applied.

Accordingly, the EEG signal introduced through the driving electrode RAE or LAE and the reference electrode RRE or LRE has a high input impedance and a high common component removal ratio, and constitutes the op amp OP3 constituting the differential amplifier 205. The inverting terminal and the non-inverting terminal of are respectively input through the resistor R2. The non-inverting differential amplification is performed with a predetermined gain based on the resistor R3. The amplification ratio is set within the range in which the op amp OP3 is not saturated by the DC offset. In this circuit diagram, the resistor R2 and the resistor R3 are set to 200 Hz and 4.99 Hz, respectively, to present an amplification ratio 25 times.

The amplified differential signal is subjected to the low frequency blocking by the RC circuit, that is, the capacitor C2 and the resistor R5, through the DC offset elimination filter 207 described above. Generate the cutoff frequency of. This cuts the DC signal of 0.16 kHz or less, and outputs only the higher frequency through the resistor R6 to the high frequency cut-off filter 209. This is to block the high frequency signal of 250 kHz, and to detect epilepsy, the high frequency of 100 kHz or more is observed and the cerebral ischemia is detected in the low frequency region of 30 ㎐ or less and 0.16 ㎐ or more. The frequency is amplified once more via the amplifier 211.

This is to amplify the EEG signal amplified by 25 times in the differential amplifier 205 40 times, so that the total amplification ratio of the preamplifier 101 is set to 1000 times (25 × 40). That is, the op amp OP5 divides the feedback signal from the resistor R9 and the resistor R10 so that the amplification is 40 times. Accordingly, the resistor R9 is set to 365 mV and the resistor R10 is set to 15 mV to obtain the output value of R10 / R9.

As a result, by amplifying and outputting 1000 times the frequency of 0.16 kHz or more and 250 kHz or less of the EEG signals, the amplified frequency signal is transmitted to the separation amplifier 213 for transmitting without noise to the main amplifier 103.

On the other hand, the preamplifier 101 does not use a body driver circuit commonly used in the conventional biometric amplifier, thereby limiting the influx of oscillation and noise caused by instability due to the feedback loop of the body driver circuit. have.

The separation amplifier 213 separates the power supply and the ground of the preamplifier 101 and the main amplifier 103 by using an element IC using an optical coupling method. This is to remove digital switching noise due to A / D converting when the EEG amplification signal is input to the controller 103, and uses an 'ISO 100' device. The signal output through the device IC is applied to the main amplifier 103.

Here, the preamplifiers (101-1 channel) are paired to monitor the EEG on the left or right side of the patient equally, so the preamplifier (101 '-2 channels) for monitoring the EEG on the right or left side. Will be omitted.

On the other hand, in addition to the plurality of electrodes (RAE, RRE, LAE, LRE) for monitoring the EEG on the left or right of the patient, a terminal (E) for limiting the current flowing into the patient is used, in detail according to the accompanying drawings. The explanation is as follows.

3 is a circuit diagram showing the current limiting circuit section 301 together with the preamplification sections 101 and 101 '. The current limiting circuit unit 301 is to prevent damage to the amplifying unit when a high voltage above the reference value flows through the differential amplifier 205 and the buffer 201 so that the power by the amplifying unit is not exposed to the patient. After the field effect transistors FET1 and FET2 are connected in series, the preamplifier 101 is connected to the common ground GND. Therefore, as the current flowing into the patient is minimized through the electrodes RAE, RRE, LAE, and LRE, the EEG signal of the patient is normally detected at the same time as the patient is stabilized.

On the other hand, when the EEG signal is detected according to a predetermined level amplification, it is to be amplified according to the user's intention through the main amplifier 103, it will be described in detail based on the accompanying drawings.

4 is a block diagram showing the main amplifier 103 in one embodiment. 5A and 5B are circuit diagrams illustrating FIG. 4. First, the main amplifier 103 receives an EEG signal output from the preamplifier 101, that is, a 1-channel EEG signal detected by the left brain and a 2-channel EEG signal detected by the right brain. A low pass filter 401 for removing components, a DC offset filter 403 for removing DC components in signals flowing through the respective low pass filters 401, and an output from the DC offset filter 403. Notch filter (407) for removing an artificial noise frequency corresponding to 60 Hz among the left and right EEG signals, and for selectively selecting the signals output from the notch filter (407) and the buffer (405). A multiplexer 409 and a frequency signal of one side selected by the multiplexer 409 are input, and when the output signal of the notch filter 407 is selected, the digitized signal outputted therefrom is converted into an analog signal. A low pass filter LP1, a variable low pass filter 411 for tuning the frequency applied through the low pass filter LP1 to a frequency corresponding to an external variable clock signal, and the variable low pass filter A low pass filter LP2 for converting the digitized signal output from 411 into an analog signal, and a high pass filter HP for detecting high frequency components of the signals applied through the low pass filter LP2 for each band. And a variable gain controller 413 for selectively adjusting gain of the signal detected by the high pass filter HP.

Each buffer 405 (B) is connected to the output terminals of the DC offset elimination filter 403 and the notch filter 407 to be applied to the multiplexer 409.

On the other hand, the low pass filter 401 has a low-pass circuit consisting of a resistor (R11), a resistor (R12) and a capacitor (C12) is connected to the non-inverting terminal of the op amp (OP11), the resistor (R11) and the capacitor A series circuit composed of C11 is connected to an inverting terminal, and the DC offset elimination filter 403 is composed of a capacitor C13 and a resistor R13, and the buffer 405 is formed of an op amp OP12. The notch filter 407 is provided with an IC IC2 for setting a filtering frequency corresponding to 60 Hz through the terminal CN1, and the buffer B has a resistor R14 around the op amp OP13. R15 is configured.

The multiplexer 409 includes an IC IC6 to receive a selection signal from the terminal CN2. Low-pass filter LP1 is provided with an op amp OP16, a resistor R16 (R17) and a capacitor (C15) is connected to the non-inverting terminal and a resistor (R16) and a capacitor (C14) is connected to the half terminal. . In addition, the variable low pass filter 411 is composed of IC (IC3) (IC3 '), the low pass filter LP2 is a resistor (R18) (R19) and capacitor (C16) (C17) is the op amp (OP17) Each input terminal of is connected. The variable high pass filter HP is provided with an IC IC for allowing a plurality of fixed resistors RR1 to be selected by the terminal CN4 around the capacitor C18, wherein the high pass filtered signal is an op amp. It is made to go through a buffer consisting of (OP18).

The variable gain controller 413 selects one of the plurality of resistors RR2 through one terminal CN5 to select one of the resistors RR2 and one side selected from the IC IC5 and IC5 '. The op amp OP19 whose amplification gain is set by the resistor and the fixed resistor R24, and the op amp OP20 and capacitor performing buffering to output the signal amplified by the op amp OP19 to the controller 105. C19 is provided.

Hereinafter, the operation of the main amplifier 103 according to the above configuration is as follows.

First, the left / right EEG signals detected by the preamplifier 101 are applied to the main amplifier 103 through a signal transmission line of a predetermined length, which is a power source used in the main amplifier 103 and a plurality of external sources. This is to reduce the influence on the EEG signal detected by the preamplifier 101 by the factor. Therefore, when the EEG signal output from the preamplifier 101 flows into the channel 1 and the channel 2 of the main amplifier 103, only the low frequency signal is detected through the two low pass filters 401.

The blocking of the high frequency signal is determined by the resistor R12 or the resistor R11, the capacitor C12, and the capacitor C11, and the blocking frequency is determined and buffered through the op amp OP11 constituting the unit gain amplifier. Here, the resistors R11 and R12 are 4.99 kV, the capacitor C12 is set to 10 kV, and the capacitor C11 is set to 22 kV to block high frequency signals of 2.151 kV or more, and are introduced through the signal transmission line. Eliminates a lot of noise

The removal of the high frequency signal of about 2.151 Hz, that is, about 2 Hz or more is for maximum protection of the EEG signal, and removes the DC component included in the frequency of 2 Hz or less through the DC offset removing filter 403. In this case, the direct current component is defined as a signal of approximately 0.16 dB or less, thereby removing the direct current component flowing through the signal transmission line. Accordingly, the DC offset elimination filter 403 implements a DC offset using 1 kHz and 1 kHz to remove frequencies below 0.16 kHz.

As such, when only a predetermined frequency band is input, the buffer 405 is output through the buffer 405. The op amps introduced through the channel 1 (CH1) and the channel 2 (CH2) are inputted to each op amp using the same circuit. To be buffered by (OP12). Since the output terminal of the op amp OP12 is connected to the input terminal of the notch filter 407, the main amplifier based on a 60 kHz clock signal (supplied by a pulse generator-not shown) applied through the terminal CN1. 60 Hz artificial noise generated from the power supply 105, the signal transmission line, and the like are eliminated. The signal passing through the notch filter 407 flows into the buffer B to be output with the gain 1 from the same resistance value of the resistor R14 and the resistor R15.

The output terminal of the buffer B is simultaneously input to each channel to the output terminal of the buffer 405 and the multiplexer 409. The multiplexer 409 selects the output signal of the buffer 405 or the buffer B by the terminal CN2 and transmits the signal to the low pass filter LP1.

That is, the EEG signals of the channel 1 and the channel 2 applied to the main amplifier 103 can be reviewed in the state including artificial noise, and the notch filter 407 can be used to examine the entire band. It is to detect the EEG signal without distortion while removing artificial noise. The EEG signal is selected based on the terminal CN2 connected to the control panel of the controller 105.

Therefore, the EEG signal selected by the multiplexer 409 filters the frequency of 2.15 kHz from the resistors R16 and R17 and the capacitors C14 and C15 configured in the low pass filter LP1. This is a Butter Worth circuit, similar to the low pass filter described above, and has a cutoff frequency of 715.7 kHz based on a ratio of equal resistance (R16) (R17) of 1.5 'and 0.1 ㎌, 0.22 인, which is the ratio of C14 ≒ 2C15. Get it. The frequency of 2.15 kHz is filtered to 715.7 kHz through an op amp OP16 used as a unit gain amplifier.

Of course, the filtering is performed for each channel and the filtered signal is transmitted to each of the variable low pass filters 411. The variable low pass filter 411 receives a sampling clock signal of up to 6 Hz from a terminal CN3 from a separate pulse generator, and filters each of a plurality of frequency bands based on IC IC3 IC3 '. At this time, the IC IC3 (IC3 ') samples the signals at a plurality of frequencies and outputs them as digitized serial signals.

On the other hand, the pulse generator sets the input frequency to the variable low pass filter 411 from the control panel provided in the control unit 105, which will be described according to the accompanying drawings as follows.

FIG. 6 is a circuit diagram for generating a clock signal used in the variable low pass filter 411 of FIG. 5A. The switch SW performs a key input by a user to set an input frequency, and from the switch SW. The vibrator generates a multiplexer IC7 for selecting one of the plurality of resistors RR3 based on the generated control signal, and a pulse signal corresponding to the tuning value of the capacitor C20 and the resistance obtained from the multiplexer IC7. It consists of (IC6).

Each output terminal of the switch SW is provided with a pull-up resistor RR4.

The pulse generator 601 according to the configuration performs decoding in the multiplexer IC7 when one of the plurality of keys included in the switch SW is selected by the multiplexer IC7. From this, the resistance of one side of the resistor RR3 corresponding to the selection key of the switch SW is set, and the selected resistance value and the tuning frequency by the capacitor C20 are generated.

The tuning frequency by RC is supplied to the vibrator IC6, and the pulse signal shaped by the vibrator IC6 is applied to the variable low pass filter 411 through the terminal CN3.

As a result, the pulse signal supplied to the terminal CN3 is determined by the selection of the switch SW, and the output frequency of the variable low pass filter 411 is determined by the pulse signal applied to the terminal CN3. These frequencies are 30 kHz, 50 kHz, 70 kHz, 100 kHz and 200 kHz, and when transmitting the EEG amplification signal to the control unit 105 to limit the sampling signal band according to the interfacing of the computer.

Accordingly, the filtering signal of the specific frequency band output through the variable low pass filter 411 is applied to the low pass filter LP2. Here, the low pass filter LP2 has a cutoff frequency of 255.6 kHz, so that the maximum filtering frequency 200 kHz output from the variable low pass filter 411 can pass safely.

This low pass frequency is set by resistors R18 (R19) and capacitors C16 (C17), wherein the resistors R18 (R19) are 4.2 GHz, the capacitor C16 is 0.22 kHz, and the capacitor ( C17) is one embodiment of the present invention using 0.1 kHz. Thus, only the frequency of 255.6 kHz or less is passed. As described above, since the output waveform of the variable lowpass filter 411 is a digitized serial signal, the frequency is the maximum value, that is, the edge of the stepped wave signal formed at the output waveform. (Edge) part is output in a gentle curved shape.

Therefore, the output signal of the variable low pass filter 411 which has passed through the low pass filter LP2 is output as an analogized signal. The signal at this time is a unique signal that is not amplified. The op amp OP17 of the low pass filter LP2 is used as a unit gain amplifier having a gain of 1, and the output signal thereof is the variable high pass filter HP. ) Is entered.

The variable high pass filter HP is for removing a DC component signal among the EEG signals output from the low pass filter LP2, and a plurality of fixed resistors RR1 are used to detect mixing of the EEG signals among the DC component signals. By changing the filtering frequency of the high pass. That is, the resistor RR1 is selected through the IC IC4 among the capacitor C18 and the resistor RR1 constituting the high pass filter. The IC IC4 is driven by supplying a switching signal to the terminal CN4 through a key panel provided in the controller 105.

As an example, if the resistor RR1 is set to 30 kV, 150 kV, 300 kV and 1 kV, respectively, and the capacitor C18 is 1 kV, the resistance RR1 is based on the selection data flowing into the terminal CN4. One side is selected to generate a tuning frequency with the capacitor C18. This change in resistance produces approximately 5.3 kHz, 1 kHz, 0.53 kHz and 0.16 kHz and is buffered through the op amp OP18. Of course, this is to buffer each channel, that is, the left EEG signal and the right EEG signal, respectively, is applied to the variable gain controller 413.

The signal input to the variable gain controller 413 is applied to the non-inverting input terminal of the op amp OP19, and a plurality of signals to be selected from the resistor R24 and the IC IC5 included in the inverting input terminal of the op amp OP19. The gain is set by one of the resistors RR2.

That is, a control signal binarized by the terminal CN5, which is generated according to a user's selection by the controller 15, is transmitted to the IC IC5, which is converted into a decimal signal to convert the plurality of resistors ( Select one resistance of RR2). Therefore, the amplification gain of the op amp OP19 is set according to the mutual ratio between the resistor R24 and the selected one resistor.

Such amplification gain is 1, 1.25, 2, 5, 10, 20, 50, 100 times and is used in the embodiment of the present invention.

On the other hand, the amplified EEG signal is output through a buffer having a high input impedance, the buffer using the op amp (OP20) as a unit gain amplifier, thereby reducing the effect of leakage current to the controller 105 to be applied later Let's do it. The EEG amplification signal introduced into the control unit 105 is displayed through a monitor of the pure EEG, alpha ratio (Percent delta), CSA, SEF and DTP of the EEG signal through a software process.

The software is graphically processed based on spectral calculations using the FFT method and adds a header to the EEG data to easily observe such information, which uses an EEG file containing patient information and file information. Then, the structure of the control unit 105 for realizing such a display is as follows.

7 is a view for explaining a display structure according to the present invention. First, an A / D converter 701 for converting an EEG signal output from the main amplifier 103 into a digital signal, and a data manager 705 for collectively managing data supplied from the A / D converter 701. ), A drive 703 for reading / memory a plurality of pieces of data under the control of the data management unit 705, and a buffer 707 for detecting pure EEG signals in the A / D converter 701 and the drive 703. ), A preprocessing unit 709 for detecting CSA and DSA signals from the output signal passing through the buffer 707, and an FFT and an average operation based on the output data of the preprocessing unit 709. And a calculator 711 for extracting a plurality of EEG parameters and a display 713 for displaying a plurality of EEG signals on a monitor.

Hereinafter, the display method of the EEG signal according to the above configuration will be described.

First, the EEG signal flowing through the A / D converter 701 is collectively controlled by the data management unit 705, which is a comprehensive function EEG analysis and data management program, by adding a header to the EEG data. Use EEG files with patient and file information. In order to manage patient information systematically and efficiently, IDs are managed in a hierarchical directory structure, and file names are automatically generated using the date and time of recording.

Such data management of the patient is illustrated in FIG. 8A as an example. For example, if you want to analyze the patient's information in real time, select "OnLine Data Acquisition" and then enter the patient's ID. The CSA, DSA, TP, DTP, Alpha ratio, and percent delta outputted through the pure EEG and operation unit 711 of the patient through the buffer 707 by clicking “Start” are displayed. It is displayed on the monitor. In addition, if you select "OffLine Data Processing" and enter the patient ID, the EEG file name is displayed in the combo box and other information is also shown.

On the other hand, if you want to save the time and content of a particular event of the patient during surgery, click the "EVT" (Event marker) of the control panel shown in Figure 8b with a mouse to record the time and content of the event. In addition to the "EVT", the control panel includes the overall gain of the patient's EEG and gain adjustment for each channel, as well as real-time digital EEG recording and post review of the recorded files during patient monitoring.

In addition to capturing and displaying up to three reference waveforms at the same time for CSA and DSA waveform comparisons, the ability to mark important records during monitoring and to instantly move to the recording section during post-review, and to jump backward and forward through the file It adds essential functions in EEG monitoring and analysis such as function, pause and complete stop function.

In addition to such data management, the display 713 displays a plurality of EEG signals. First, a pure EEG signal is as follows.

Typically, the frequency band of EEG is mainly distributed in the range of 0㎐-60㎐, and in the present invention, 0㎐-3 0 is known as delta wave (δ), 4㎐-7㎐ is known as theta wave (θ), and 8㎐-13㎐. Papa (α) and 14 Hz-28 Hz are classified as beta waves (β). The beta wave (β) is composed of a first beta wave (β1) having a band of 13 Hz-20 Hz, a second beta wave (β2) having a band of 20 Hz-50 Hz, and a gamma wave (γ) having 50 Hz or more. do. The EEG signal configured as described above is allocated to an EEG signal of approximately 95%, and is extracted at a detection frequency of about 255 kHz output from the main amplifier 103.

Of course, the main amplifier 103 detects a high frequency (255 kHz) for the detection of epilepsy, but in order to determine whether the patient's fatal state during surgery corresponding to the delta wave, theta wave, alpha wave and beta wave The state is judged using only signals below 28. Therefore, the controller 105 selects only signals of 28 kHz or less among the signals output from the main amplifier 103, and converts the selected signals into digitized signals through the A / D converter 701.

The digital signal is displayed on one side of the monitor as a raw signal of raw brain waves (raw electron-phalogram). In other words, the left EEG signal output from one channel and the right EEG signal output from two channels are displayed by digitizing the data itself in units of frames over time. The pure EEG signal is illustrated in FIG. 9A.

Meanwhile, after performing FFT (Fast Fourier Transform) and Averaging on the data of the pure EEG signal, the extracted spectra are virtually three-dimensionally processed and then compressed spectral array is processed. ) Makes it easy to observe the state of change in cerebral blood flow. In addition, the CSA designates colors for each frequency band so that δ, θ, α, and β waves of EEG components can be visually displayed.

The CSA signal can be observed in a patient's coma or hypotension, and when the two-channel CSA signal and pure EEG signal are used, it is easy to detect cerebral ischemia in carotid endarterectomy. .

Such a CSA signal is as shown in FIG. 9B, and the spectrum shown in the figure causes a spectral edge frequency (SEF) to be displayed, which is a cumulative sum of the power of the EEG signal from 1 Hz. In Equation 2, the edge frequency at the boundary of the section where the total power is concentrated is used as a parameter to know the power distribution of the EEG signal.

In addition, in the present invention, in displaying the CSA signal, the hourly display and the color-specific display are enabled, and the hourly display is performed for several ten hours at an interval of two seconds in one embodiment. This feature allows for comprehensive observation of the patient's condition and review of the EEG detection data of the patient during patient monitoring.

In addition, the EEG signal is converted into an A / D FFT, and then converted into the CSA signal, and then converted into a DSA (Density Spectral Array). The DSA also becomes a virtual three-dimensional display of a technique such as CSA. The DSA divides the maximum and minimum values of the spectral power into a plurality of grades to give colors for each grade.The DSA is divided into all 14 grades, the frequency range of maximum power is red, and the frequency range of minimum power is ultra blue. In the example.

In displaying the DSA signal on a monitor, the vertical axis is used as the time axis, the horizontal axis is used as the frequency band, and approximately tens of hours or more are simultaneously displayed. This is illustrated by the contrast in FIG. 9C.

On the other hand, a number of parameters can be extracted by the CSA and DSA data, including the total power (TP) for detecting the cerebral activity state of the patient, and the power ratio of alpha wave, theta wave and delta wave. The alpha ratio for detecting and determining the patient's mental stability, the percentage delta for determining the likelihood of brain damage in an unconscious patient through the power of the delta wave and the power of the entire frequency band, and Difference in Total Power (DTP) is used to detect the activity of left and right brain waves.

Here, the total power TP calculates the sum of the signal powers at 1 kHz to 28 kHz, except for the 0 kHz signal, which is a direct current component. That is, the digitalized information obtained by calculating Fourier integrals of the left and right EEG signals flowing into the control unit 105 is displayed on a graph as shown in FIG. 9C. It is indicated by a thick white line. The total power TP is expressed by the following equation.

TP = full power

X (f) = spectral density of energy by frequency

On the other hand, the alpha ratio is to calculate the frequency band power of the alpha wave and the frequency band ratio less than the alpha wave frequency, it is to detect the mental state of the patient through the brain waves. In other words, the stable alpha wave represents the power ratio with the unstable theta wave and the delta wave, which is used as information for the patient in the operating state to determine the stable state of the brain during surgery. The alpha ratio is calculated by dividing the frequency of the alpha fine 8 kHz-13 kHz by the delta and theta fine 1 kHz-7 kHz, and is expressed by the following equation, and displays a signal waveform as shown in FIG. 9D.

P (α) = alpha ratio

The alpha ratio is displayed on the monitor with different colors for each channel, and the percentage delta is a ratio of delta wave and power of the entire frequency band, and the delta wave that may occur during brain injury occupies relatively power in the entire frequency band. Indicates a ratio. Percent delta is also easy to identify by different colors for each channel, the percentage delta is expressed by the following equation.

P (δ) = percent delta

The graph based on the above equation is shown for each channel in FIG. 9E. When the DSA and the TP are displayed for each channel, the difference in spectral power for each channel (Difference in Total Power: DTP) is simultaneously displayed so that the activity of the brain waves can be detected. This calculates a power difference obtained by subtracting the total power of the right brain wave from the total power of the left brain wave. The calculation result is graphically processed in the form of a horizontal bar graph between the two DSAs shown in FIG. 9C, and the calculation process of the DTP is based on the following equation.

LTP = total power of the left brain

RTP = total power of the right brain

DTP = total power difference

As described above, the EEG signal of the patient can be displayed purely, or the EEG signal can be processed and displayed on a monitor as shown in FIG. 10 to facilitate immediate comparison and determination of the brain activity state of the patient during surgery.

According to the present invention, in addition to the hardware design of the EEG amplifier for monitoring EEG, the EEG signal obtained from the EEG amplifier can be displayed or processed purely to enable comprehensive and objective patient observation during surgery. Get

First, EEG data can be reviewed after monitoring by displaying key parameters related to EEG on one screen, and the EEG data can be reviewed afterwards. Easily detect changes in EEG by assigning multiple colors for each frequency of characteristics, and by instantly displaying a number of EEG parameters, it is possible to instantly compare and judge left and right brain activity status and monitor patient during fourth operation. When you want to save CSA, DSA, TP, SEF at a certain moment and compare it with the postoperative state, it displays a lot of information at the top of the screen, making it easy to compare the information data and record the fifth patient's first aid. Equipped with a file management function that can enter the effect of improving the usability of the system have.

Claims (10)

In the brain function monitoring device, An artificial noise removing filter 201 configured as a balanced filter to remove the artificial noise of the electric meat at the first stage of the input; A buffer 203 for the signal flowing from the artificial noise removing filter 201 to have a high impedance; A differential amplifier 205 for differentially amplifying the OPRR with a high CMRR to have a common mode rejection ratio even at a high frequency generated from the electric meat to remove the common mode signal; A low frequency cut filter (207) for removing direct current offset from the signal output from the differential amplifier (205); A high frequency cut filter 209 for removing high frequency noise of 250 kHz or more from a signal flowing through the low frequency cut filter 207; An amplifier 211 for amplifying the EEG measurement frequency through the high frequency cutoff filter 209 with a predetermined gain; And a separation amplifier for removing the high frequency digital switching noise included between the power supply line of the preamplifier 101 and the main amplifier 103 and the ground in transmitting the amplified signal of the amplifier 211 to the main amplifier 103. An amplification unit 101 for monitoring cerebral ischemia through left and right electrodes LAE, LRE, RAE, and RRE; A notch filter 407 for removing artificial noise of commercial power 60 kHz introduced through the preamplifier 101; A low pass filter 401 for removing noise of 2.15 kHz or more generated by the signal transmission line in transmitting the signal from the preamplifier 101 to the main amplifier 103; A DC offset removing filter (403) for removing a DC signal among the EEG signals applied through the low pass filter (401); A multiplexer 409 for selecting one side of signals output from the DC offset elimination filter 403 and the notch filter 407; A variable low pass filter 411 for variably limiting a signal band according to a sampling band of a computer to interface an EEG amplified signal with the controller 105; A variable high pass filter (HP) for variably restricting the DC signal of the signal passing through the variable low pass filter (411) through the terminal (CN4); And a variable gain controller 413 for amplifying the variable signal output by the variable high pass filter HP to a predetermined level from the control signal through the terminal CN5. ); And Brain by using the digital EEG, characterized in that the control unit 105 to read the amplified signal of the preamplifier 101 to adjust the amplification gain of the input signal, to extract a variety of EEG parameters to achieve a multi-dimensional display Function monitor. According to claim 1, wherein the preamplifier 101 is a current limiting circuit for preventing damage to the amplifier and damage to the amplifier when the high voltage above the reference value flows by an internal circuit ( Brain function monitoring device using a digital brain wave, characterized in that it further comprises 301). delete delete The low pass filter LP1 for blocking a frequency of 715.7 Hz or more and the low pass filter LP2 for blocking a frequency of 255.6 Hz or more are respectively provided on an input and output side of the variable low pass filter 411. Brain function monitoring device using a digital brain wave, characterized in that it further comprises. 2. The artificial noise canceling filter (201) according to claim 1, wherein the artificial noise removing filter (201) is connected with the same resistor (R1) to each electrode, and a capacitor (C1) is provided between the resistors (R1); The buffer (203) is connected to the non-inverting terminal of the op amps (OP1, OP2) implemented with the resistor R1 as a unit gain amplifier; The differential amplifier 205 differentially amplifies the signal flowing from the buffer 203 through the resistor R2 and the op amp OP3, and is connected to set an amplification gain based on the resistor R3; The DC offset elimination filter 207 is connected to a DC signal blocking filter by a capacitor C2 and a resistor R4; The high frequency cut-off filter 209 is connected to the op amp (OP4) and the input and feedback side of the op amp (OP4) in order to cut only below a specific frequency in order to extract only the frequency band suitable for EEG measurement. R7), a Butter Worth circuit composed of capacitors C3 and C5, and a low pass filter circuit composed of a resistor R8 and a capacitor C4 connected to the output terminal of the op amp OP4; The amplifier 211 comprises an amplifier op amp OP5 and resistors R9 and R10 for setting the gain of the op amp OP5; The separation amplifier 213 is digital, characterized in that the IC (IC), which is an optical coupling amplification element in order to avoid the signal noise in the signal transmission from the preamplifier 101 to the main amplifier 103 Brain function monitoring device using brain waves. The low pass filter 401 of claim 1, wherein the low pass filter 401 includes a low pass circuit composed of a resistor R11, a resistor R12, and a capacitor C12, connected to a non-inverting terminal of the op amp OP11. A series circuit consisting of R11) and capacitor C11 is connected to the inverting terminal of op amp OP11; The DC offset elimination filter (403) is composed of a capacitor (C13) and a resistor (R13); The notch filter 407 is provided with an IC IC2 for setting a filtering frequency corresponding to 60 Hz through the terminal CN1; The multiplexer 409 is configured to receive a selection signal from a terminal CN2 via an IC IC6; The variable low pass filter 411 is composed of ICs IC3 (IC3 ') which vary the filtering frequency from the pulse signal applied to the terminal CN3; The variable high pass filter HP is provided with an IC IC4 for allowing a plurality of fixed resistors RR1 to be selected by the terminal CN4 around the capacitor C18; The variable gain controller 413 selects one of the resistors RR2 through a terminal CN5 to select one of the resistors RR2 and one resistor selected from the IC IC5 and IC5 '. And an op amp OP19 having an amplification gain set by the fixed resistor R24, and an op amp OP20 that buffers the signal amplified by the op amp OP19 to the controller 105. Brain function monitoring device using a digital brain wave, characterized in that. Digitally processing the EEG signal of the amplified patient through the left and right two channels, and displaying the pure EEG generated therefrom on a monitor; Displaying the digitized pure EEG signal in virtual three dimensions by extracting a spectrum through FFT and averaging; Displaying a DSA signal obtained by virtually three-dimensional processing the FFT spectral power of the pure EEG signal; Displaying a total frequency power (TP: Total Power) included in 1 kHz to 28 kHz of the left and right respective EEG signals; Displaying a spectral edge frequency (SEF) indicating a time point of accumulating the power of the pure EEG signal from 1 kHz to 95% of the total frequency power (TP); Displaying an alpha ratio obtained by graphically processing the ratio of the frequency band power of α wave and the frequency band power of θ and δ wave of the EEG signal; Displaying a percentage delta obtained by graphically processing the percentage of power occupied by the δ wave in the entire frequency band; And Graphically processing the difference in total power (DTP) calculated from each of the left and right brain waves, and capturing and displaying CSA, DSA, TP, SEF, etc. of the patient state at a specific moment on the screen. A method of displaying digital brain waves in a brain function monitoring apparatus using digital brain waves. The method of claim 8, wherein an EEG file including patient information and file information corresponding to a patient ID is generated by adding a header to the pure EEG data, thereby enabling event marking and searching of records. And managing the patient ID in the form of a hierarchical directory structure. The method of claim 8, wherein the displaying in the virtual three-dimensional image is performed by assigning colors to frequency bands of the CSA signal and assigning colors of grade 14 to the spectral power of the DSA signals in the third display process. A method for displaying digital brain waves in a brain function monitoring apparatus using digital brain waves.