JPS6335232A - Circuit apparatus for recording induced potential - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Field of Application in Industry -■-] The present invention is capable of recording ABR (audit
The present invention relates to an evoked potential recording circuit device for recording an evoked signal addition waveform such as a brain stem response signal.

[Problems to be solved by the conventional technology and the invention] When determining brain death based on brain stem dysfunction, it is necessary to not only confirm the transition of brain waves to a flat waveform on recording paper, but also record respiratory waves or induce A method of checking the summed waveform of brain-evoked signals such as ABR signals detected by a potential monitoring device using an X-Y plotter is well known. However, simultaneous and continuous measurement of evoked signals and electroencephalograms has placed a heavy burden on medical institutions both operationally and economically.

Therefore, it is difficult to make the waveforms of the three elements correspond to each other over time, which poses a problem in terms of diagnostic accuracy. Furthermore, it was not possible to preserve appropriate materials for later reconsidering the decision.

Therefore, the present invention focuses on the fact that there is a close correlation with changes in evoked signals during the transition process to flat brain waves, and at least records ABR waveforms along with brain waves on the recording paper of the same recording device for comparison. The object of the present invention is to provide a circuit device for recording evoked potentials.

[Means for solving problems]

In order to achieve this purpose, we have already applied for patent application No. 61-8704.
No. 8 proposes a circuit device for recording evoked potentials that outputs an analog signal. In contrast, the present invention is based on the premise that waveforms can be recorded in a digital recording device using a line-shaped dot printing element, etc., and as shown in FIG. The evoked potential recording circuit device was constructed as follows. That is, an induced signal detection circuit 10 that detects an induced signal such as an ABR signal induced in an electrode 3 attached to the head in response to stimulation such as sound or electricity from the stimulation device 2, an adder 11a, and a memory. llb, and adds the contents of this memory to the digitalized inducing signal output from the inducing signal detection circuit IO and writes the addition result to the memory Ilb, thereby accumulating the inducing signals for multiple stimulations. The signal addition circuit 11 and the memory 11 are used to write data on the recording paper 1a at the same time.
A memory read control circuit 12 reads out the addition triggering signal at a speed S lower than the addition and writing speed so that the waveform b is easily readable on the recording paper directly or through a buffer memory, and a memory readout control circuit 12 reads out the addition triggering signal at a speed S lower than the addition and writing speed, and converts the read addition triggering signal into a digital type. It consists of a recording output circuit 13 that converts and outputs a digital signal compatible with a recording device.

This circuit arrangement for recording evoked potentials can be made into a separate unit and can be attached as an option to the digital recording device 1, or can be built into it. The evoked signal detection electrode 3 may be used in common with the electrode for electroencephalogram measurement, or a dedicated electrode may be separately attached to the head. The memory read control circuit 12 may be configured with a CPU as the addition/write control section of the induced signal addition circuit 11, so that this CPU may also be used.The induced waveform may be drawn in a time-sharing manner on the same channel as the brain waves. , or on a dedicated channel. Also, recording paper! By adding a 1-hour marker generation circuit 14 to more reliably analyze the induced waveform at point a, it is possible to generate a digital marker signal for measuring the time width of the addition induced waveform in synchronization with the readout of the memory Ilb. By adding an addition number data generation circuit 15 and an amplitude marker generation circuit 16, it is also possible to similarly generate addition number data and digital signals for amplitude measurement markers.

[Effect]

When the stimulation device 2 repeatedly generates stimulation, the induced signal detection circuit is activated each time! 0, an induced signal with a higher frequency component than the brain waves is detected. Each induced signal is generated by an induced signal addition circuit 11.
The triggering signal that has been digitized and stored in the memory Ilb and the newly input triggering signal are added to the adder 11a.
An addition triggering signal is obtained by adding the signals and storing them in the memory llb again. This addition induced signal is read out by the memory readout control circuit 12 at a speed corresponding to the frequency component ratio of the brain wave and the induced signal. Then, the recording output circuit 13 converts it into the interface conditions of the digital recording device 1 and sends it out. Here it is, recording paper!
The evoked waveform is also written in al- so that it can be compared with the electroencephalogram waveform. If desired, markers or other data supplied from the time marker generation circuit 14, addition number data generation circuit 15, and amplitude marker generation circuit 16 can also be drawn at the same time.

[Embodiments of the invention]

In FIG. 2, 20 is a thermal electroencephalograph equipped with a thermal head in which line-shaped dot printing elements are arranged. The electroencephalogram amplifier section 21, its output signal, and a specially provided interface 22d (
The recording section 22 generates a digital print signal based on an output signal from a device (to be described later) and records the waveform on recording paper. This recording section includes a multiplexer 22a that repeatedly selects the amplified output of a plurality of channels of the electroencephalogram amplifier section 21, an A/D converter 22b that digitizes the selected signal, and temporarily stores the digitized amplified output. an interface 22d that transfers a digital output signal from the recording output circuit 42 of the ABR unit 30 and a control signal to the CPU 4+ (both will be described later); Buffer RAM22
a CPU 22e that sequentially converts the digital signal stored in the RAM into dot data for each print line; and a dot print signal generation circuit 22f that converts this dot data into a dot print signal for driving the thermal head. and a drive circuit 22g which is supplied with this dot data and drives the corresponding printing element of the thermal head to draw a waveform in a dot manner on the recording paper 22h.

The ABR unit 30 includes a two-channel ABR signal detection circuit 31 consisting of a bandpass filter to which two channels of electroencephalogram signals from the electroencephalogram amplifier section 21 are bypass-input.
．． 31a, a switch circuit 32 that alternately selects these output signals at high speed, an A/D converter 33 that sequentially digitizes the selected signals, and a RAM for addition processing.
34 and the RAM 3 for addition processing by performing data acquisition processing for the output signal of the A/D converter 33 at high speed.
4 DMA for data import processing (dir
ect memory access) circuit 35, a time marker generation circuit 37 that generates pulsed markers at predetermined time intervals for the marker channel of the recording section 22, and an addition number data generation circuit that outputs a signal for drawing a code representing the cumulative number of stimulations. circuit 38, an amplitude marker generation circuit 39 that generates a digital signal for waveform-drawing a start marker of a unit amplitude and ABR waveform, and a stimulation signal generation circuit 39 that generates an audible sound stimulus by driving a speaker 44 at intervals of 100 layers S.
o By incorporating Q 40, CPU 41, and RAM, 20 channels of addition processing RAM 34 can be used.
Addition result for each cumulative stimulation of 0 times 1 hour marker generation circuit 3
7. The recording output circuit 42 takes in the output signals of the addition count data generation circuit 38 and the amplitude marker generation circuit 39 and compiles digital signals in a predetermined time series format.

Furthermore, an x-y plotter 43 is attached to the BR unit 30, and by operating a switch thereof, a waveform of the BR signal can be plotted on the addition stored in the RAM of the recording output circuit 42.

The CPU41 has built-in ROM, RAM, etc.
The addition processing RAM 34.
Configures an ABR signal addition circuit together with the RAM of the data capture processing DMA circuit 35 and the recording output circuit 42,
It also constitutes a memory read control circuit that reads out the addition results every 200 times from the addition processing RAM 34 in approximately 2 seconds, which is slower than the addition processing time, and further includes the respective sections 22c,
The control w4 of the operation timing from 32.37 to 39.40 is performed.

As shown in FIG. 3, the breathing sensor 27 includes: 1; a contact surface 271 to each inner part; and a facing part 272 to both nasal cavities;
．． 273 and a portion 274 facing the oral cavity, the heat-sensitive element holder 270 is integrally formed, and the three facing portions 2
Attaching heat-sensitive elements 278 to 278 such as three thermistors or thermocouples connected in series or parallel to the base so as to detect the respiratory heat at 72 to 274 and output a composite signal of the detection signals, respectively, The holder 270 is configured by leading out a lead @ 275 for sending out a composite signal. The contact surface 271 is then fixed to the midline of the upper lip with adhesive tape or the like, and the lead wire 275 supplies one channel of input signals to the electroencephalogram amplifier section 21.

The operation of the brain function monitoring device configured using the ABR unit 30 described above is as follows.

In the electroencephalograph 20, the multi-channel electroencephalogram induced by the electroencephalogram electrode group 2B and the l-channel respiratory wave synthesized and detected by the respiratory sensor 27 are usually written on the recording paper 22b.

When the ABR unit 30 is set in the electroencephalograph 20, the two channels of electroencephalogram signals are inputted, and the recording output circuit 42 outputs a recording digital signal.

The CPU 41 repeatedly outputs a pulse signal to the stimulation signal generation circuit 40 at intervals of 1001S, and causes the speaker 44 to generate a click stimulation sound. As a result, the brain wave signal on which the ABR signal is superimposed is input to the ABR signal detection circuit 31.31a, and the brain wave component is removed. The cpuit operates the switch circuit 32 in synchronization with the stimulation, causes the AC RF to select the two-channel BR signal at high speed, and converts it into a digital ABR signal by the A/R) converter 33.

The output of the data acquisition processing DNA circuit 35 is added by the CPU 41 to the addition ABR signal of each channel read from the addition processing RAM 34 in synchronization with the aforementioned selection operation, and the addition result is stored in the RAM 34. 20
When 0 stimulations are reached, the CPU 41 transfers the data in the addition processing RAM 34 to the recording output circuit 42, and operates the 1-hour marker generation circuit 37, addition number data generation circuit 38, and amplitude marker generation circuit 39.

The recording output circuit 42 has 512 ABRs in the time axis direction.
A digital signal corresponding to a predetermined time-division display format of the recording paper 22h-1- is created by taking in the data, start marker, amplitude marker, and addition count data for two channels and the time marker of the dedicated channel. CP■2
2e is an interface 22d from the output circuit 42 for electroencephalogram signals and recording of each channel stored in the RAM 22c;
The signals from the dots are taken in and converted into dot data for each line, and the converted dot print signals are sequentially printed on the recording paper 22h by the dot print signal generation circuit 22''.

As a result, as shown in FIG. 4 (only one channel of the ABR waveform and the marker channel are shown), a code signal A indicating 200 times and a start marker C are generated from the addition number data generation circuit 3B. . Next, the summed ABR signal for about 2 seconds and the amplitude marker B from the amplitude marker generation circuit 39 are output, and at the same time, the time marker D is output to the marker channel. After about 3 seconds have elapsed, the acquisition of the signal from the interface 22d is interrupted and the brain waves are drawn again, and when about 20 seconds have elapsed, an ABR signal of 400 additions is drawn, and the code signal A becomes a code that means 400 times. . 2.00 while drawing the cumulative result every 200 times.
When the number reaches 0, the addition operation is ended and a new measurement is started.

As a result, normal brain waves, ABR waveforms, and respiratory waves are drawn on the same recording paper over time. Respiratory waves are caused by the heat-sensitive element 276 facing the face due to nasal congestion or mouth closing.
Even if 278 no longer detects breath air, those of the remaining heat sensitive elements are monitored.

Note that the respiratory sensor 27 is connected to two measuring tools 1- along the lip anastomosis.
The total number of heat-sensitive elements can be increased to four or more by arranging a number of heat-sensitive elements. As a respiration sensor, a single conventional respiration sensor may be used, but if the respiration wave is abnormal,
The breathing sensor will need to be checked or replaced. Alternatively, if multiple locations are to be monitored simultaneously, it is necessary to derive corresponding lead wires and display waveforms on multiple channels.
The circuit portion of the ABR unit 30 can also be built into the electroencephalograph 20. The added ABR waveform can be drawn in a dedicated channel instead of being drawn in a time-sharing manner with the electroencephalogram waveform. Furthermore, the present invention can be implemented in the same manner even when an evoked potential waveform generated by a stimulation method such as electrical stimulation is recorded instead of an audible stimulation generated from the speaker 44.

〔Effect of the invention〕

Below-1-1 According to the present invention, the minimum required items for determining brain death, such as electroencephalograms, respiratory waves, and evoked potential waveforms, can be measured and recorded simultaneously and economically with one device. This allows for easy and highly accurate monitoring of brain function, including brain death determination, and is also useful as material for post-mortem reexamination.

[Brief explanation of the drawing]

FIG. 1 is a circuit configuration diagram of an evoked potential recording circuit device according to the present invention, FIG. 2 is a circuit configuration diagram when the present invention is implemented as a brain function monitoring device, and FIG. 3 is a perspective view and a diagram of the respiration sensor. FIG. 4 is a diagram of the recorded waveform.

Claims (5)

[Claims] (1) An evoked potential recording circuit device for recording at least an evoked waveform along with an electroencephalogram on a common recording paper of a digital recording device that records waveforms using digital print signals, which It has an induced signal detection circuit that detects an induced signal induced in the attached electrode, an adder, and a memory, and adds the contents of this memory and the digitized induced signal output from the induced signal detection circuit. an inducing signal addition circuit that sequentially adds the inducing signals that respond to a plurality of stimulations by rewriting the addition result to the memory; It comprises a memory read control circuit that reads at a speed slower than the addition and writing speed, and a recording output circuit that converts the read addition triggering signal into a digital signal matching the digital recording device and outputs it. circuit device. (2) The circuit device according to claim 1, wherein the electrode for detecting the evoked signal is used in common with the electroencephalogram recording electrode. (3) By providing a time marker generation circuit, the recording output circuit outputs a digital marker signal for measuring the time width of this signal together with the digital addition trigger signal. circuit device. (4) The circuit according to any one of claims 1 to 3, wherein the recording output circuit outputs a digital marker signal for amplitude measurement together with a digital addition inducement signal for recording by including an amplitude marker generation circuit. Device. (5) The circuit according to any one of claims 1 to 4, wherein the recording output circuit outputs a digital signal representing the number of additions together with the recording digital addition inducement signal by providing the addition number data generation circuit. Device.