JPS62243534A - Circuit device for recording induced potential - Google Patents

Abstract

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

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention provides an apparatus for recording ABR (audit
The present invention relates to an evoked potential recording circuit device for recording an evoked signal summation waveform such as a brain response signal.

[Problems to be solved by the conventional technology and the invention] When determining brain death based on the brainstem suspension, it is necessary to not only confirm the transition of the brain waves to a flat waveform on recording paper, but also record the respiratory waves. A method of checking the summed waveform of a brain evoked signal such as an ABR signal detected by an evoked 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. Also,
Appropriate materials could not be preserved to later reconsider the decision.

Therefore, the present invention focuses on the fact that there is a close correlation with changes in induced signals in the process of transition to flat electroencephalograms, and the present invention provides an induction method in which at least ABR waveforms are written on the recording paper of the same recording device so that they can be compared with electroencephalograms. An object of the present invention is to provide a circuit device for recording potential.

[Means for Solving the Problems] In order to achieve this object, the present invention provides an evoked potential recording circuit device to be attached to a recording device l for drawing electroencephalogram waveforms, as shown in FIG. It was configured 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 by adding the contents of this memory and the digitized inducing signal output from the inducing signal detection circuit IO and writing the addition result to the memory llb, the inducing signals for multiple audible sound stimuli are accumulated. The triggering signal addition circuit 11 reads the addition triggering signal at a speed slower than the adding and writing speed so that the waveform is easily readable on the recording paper 1a, either directly or through a buffer memory, so as to write the addition triggering signal on the recording paper 1a. It consists of a memory readout control circuit 12 for outputting data, and a recording addition induction signal output circuit 13 that performs analogization, amplification, etc. of the read m-calculation induction signal.

This evoked potential recording circuit device is made into a separate unit and can be attached to the recording section W11 as an option, or is built into the recording section W11. 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 has the addition/write control section of the induced signal addition circuit 11 configured by a CPU, so that
This cPU may also be used, and the induced waveform is drawn in a time-sharing manner on a channel common to the brain waves, or is drawn on a dedicated channel.

In addition, in order to more reliably analyze the induced waveform on the recording paper 1a, a time marker generation circuit 14 is provided to generate a marker for measuring the time width of the added induced waveform in synchronization with the readout of the memory llb. By adding the acquisition/addition count data generation circuit 15 and the amplitude marker generation circuit 1B, it is also possible to generate addition count data and amplitude measurement markers in the same way.

[Effect]

When the stimulation device 2 repeatedly generates stimulation, the induced signal detection circuit is activated each time! At O, 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 trigger signal that has been digitized and stored in the memory llb and the newly input trigger 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 slow speed corresponding to the frequency component ratio of the brain wave and the induced signal. The signal is then converted into an analog signal by the recording addition inducement signal output circuit 13, processed to match the recording device 1, and supplied to the recording device 1. As a result, the induced waveform is written on the recording paper la so that it can be compared with the electroencephalogram waveform. If desired, a time marker generation circuit 14. Markers or other data supplied from the addition count data generation circuit 15 and the amplitude marker generation circuit 1B can also be drawn at the same time.

[Embodiments of the invention]

In FIG. 2, reference numeral 20 denotes a pen-writing type electroencephalograph, which receives detection signals from an electroencephalogram electrode group 2B and a breathing sensor 27, and is composed of an electroencephalograph amplifier section 21 that amplifies the signals, and a pen recording section 22. It is configured. This electroencephalograph 20 has A
BR unit) 30 can be plugged in, and when this unit is attached to the input section 2, the contact 29 opens and the 2-channel brain wave signals are bypassed.

The ABR unit) 30 includes a two-channel ABR signal detection circuit 31.31a consisting of a pass filter, into which the two-channel electroencephalogram signals of the electroencephalogram amplifier section 21 are respectively input, and these output signals. an A/D converter 33 that sequentially digitizes the selected signal; an RA 34 for addition processing; A DMA for data import processing that performs data import processing at high speed and stores it in the RAM 34 for addition processing.
(direct memory access) circuit 3
5 and the addition results for each 200 cumulative stimulations are stored in the RAM 34.
A buffer memory for taking in the data, that is, an output RAM 3B,
Generates pulse-like markers at predetermined time intervals and writes them to the pen recording section 2.
Time marker generation circuit 37 that outputs to the second marker channel
, an addition number data generation circuit 38 that outputs a signal to draw a code representing the cumulative number of stimulations, and a unit amplitude and AB
An amplitude marker generation circuit 33 that generates a digital signal for drawing the start marker of the R waveform; a digital latch circuit 40.40a that holds the two-channel addition ABR signal and the signal from the amplitude marker generation circuit 38; Il/A converts each latched signal into analog
A converter 41.41a, an amplifier 42.42a that adds and amplifies these analogized signals and the output signal of the addition number data generation circuit 38, and drives a speaker 48 at an interval of 100 S to generate an audible sound stimulus. It is composed of a stimulus signal generation circuit 43 that generates a signal, a switch 44 that is switched when an output signal of an amplifier 42, 42a is generated, and a CPU 45.

Further, the ABR unit 30 is attached with an x-Y plotter 43, and by operating a switch thereof, it is possible to draw a waveform of the added ABR signal stored in the output RAM 3B.

CPU4S has built-in ROM, RAM, etc., and first, by running af as an adder, the RAM 34 for addition processing,
DMA circuit 35 for data capture processing and output RAM
3B constitutes an addition circuit for the ABR signal, and reads out the addition results every 200 times from the output RAM 3B in the addition processing time, that is, at a speed of 1/20 for a stimulation period of 100 m5, about 2 seconds. It also constitutes a memory read control circuit, and further includes the respective parts 32.37 to 39.40.43.
．． Controls the operation timing of 44, etc.

As shown in FIG. 3, the breathing sensor 27 has a surface 271 that contacts the midline portion of the upper lip, and a portion 272 that faces both nasal cavities.
273 and a portion 274 facing the oral cavity, the heat-sensitive element holder 270 is integrally formed.
2 to 274, three heat-sensitive elements 2 such as thermistors and thermocouples connected in series or parallel to each other so as to detect respiratory heat and output a composite signal of the detection signals.
76 to 278 are attached, and a lead wire 275 for sending a composite signal is led out from the holder 270. 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 above ABR unit 30 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 together with a pen on the recording paper 22a.

When the ABR unit 30 is set to the input section 28, the contact 29 becomes open and the two channels of brain wave signals are input. (:PU45 is the stimulation signal generation circuit 43
A pulse signal is repeatedly outputted at an interval of 100 s, and a click stimulation sound is generated from the speaker 48. 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 CPt 145 operates the switch circuit 32 in synchronization with the stimulation, and alternately selects two channels of ABR signals at high speed, and converts the A/D converter 33 into a digital ABR signal. The output of the data acquisition processing DMA circuit 35 is the addition ABR signal of each channel read out from the addition processing RAM 34 in synchronization with the aforementioned selection operation, and the C
The PU 45 adds the sum and stores the addition result in the RAM 34. When 200 stimulations are reached, the CPU 45 causes the data in the addition processing RAN 34 to be transferred to the output RAM 3B, and causes the latch circuits 40 and 40a to hold the data of the corresponding channel. Further, the time marker generation circuit 37, the number of addition data generation circuit 38, and the amplitude marker generation circuit 38 are activated at the appropriate timing to correspond to the required display format on the recording paper 22a, and the output signal of the amplifier 42.42a is sent to the switch 44. Let them choose.

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 count data generation circuit 38. Then, the summed ABR signal for about 2 seconds and the amplitude marker B from the amplitude marker generation circuit 38 are output, and at the same time, the time marker D is output to the marker channel. After about 3 seconds, the switch 44 is reset and the brain waves are drawn again, and when about 20 seconds have passed, 400 addition ABR signals are drawn, and the code signal A becomes a code indicating 400 times. While drawing the cumulative result every 200 times, when it reaches 2,000 times, add rX
Finish the e-production and start the measurement at some point.

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 27 facing the user due to nasal congestion or closed mouth.
Even if 6-278 no longer detects breathing air, the remaining heat-sensitive elements are monitored.

Note that the respiratory sensor 27 may have four or more heat-sensitive elements as a whole, such as by arranging two or more heat-sensitive elements along the anastomosis of the lips. A single conventional respiratory sensor may be used as the respiratory sensor, but if the respiratory waves are abnormal, the respiratory sensor must be inspected 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. A
The circuit portion of the BR unit 30 can also be built into the electroencephalograph 20. The summed BR waveform can be drawn on a dedicated channel instead of being drawn in a time-sharing manner with the brain wave waveform. Furthermore, the present invention can be implemented in the same manner even when an evoked potential waveform generated by a ground stimulation method such as electrical stimulation is recorded instead of the audible sound stimulation generated from the speaker 48.

〔Effect of the invention〕

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 drawings]

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 respiratory 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 the recording paper of the same recording device, which records evoked signals induced in electrodes attached to the head in response to stimulation. It has an induced signal detection circuit for detecting, an adder, and a memory, adds the contents of this memory and the digitalized induced signal outputted from the induced signal detection circuit, and writes the addition result to the memory again. an inducing signal addition circuit that sequentially adds the inducing signals in response to a plurality of stimuli by adding the inducing signals; and reading out the addition inducing signals from the memory at a speed slower than the addition and writing speed so as to perform the simultaneous writing. A circuit device comprising a memory read control circuit and a recording addition inducement signal output circuit that converts the read addition inducement signal into an analog signal and outputs the analog signal. (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) The circuit device according to claim 1 or 2, wherein a marker signal for measuring the time width of this signal is output together with the recording addition inducing signal. (4) The circuit device according to any one of claims 1 to 3, wherein a marker signal for amplitude measurement is output together with the recording addition inducement signal. (5) The circuit device according to any one of claims 1 to 4, wherein a signal representing the number of additions is output together with the recording addition inducing signal.