RU46419U1 - RETURN NERVE NEUROMONITOR - Google Patents

Abstract

The utility model relates to medical devices for endocrine surgery of the thyroid gland for detection - monitoring of the motor nerves of the vocal cords, at an increased risk of damage during surgery. Achievable technical result is provided by means of additional automation of the device, as well as the organization of the formation of stimulating signals. The neuromonitor of the recurrent nerve is characterized by the presence of: a stimulating active electrode in the form of a search probe with a signal sensor, a neutral passive electrode installed on the patient-monitoring object, an endotracheal tube with sensor electrodes, a control unit and signal generation with functional blocks in its composition: a pulse generator for a stimulus driver for an active electrode and a modulation current driver for a passive electrode, a pulse generator for a driver I time intervals, stimulation pulse modulator, four amplifiers, four differential amplifiers, three half-wave rectifiers, four low-pass filters, four peak detectors, six sample-storage devices, four comparison devices, two counters, four indicators: three light and one sound, located at the outputs of four chains of signal processing units of the electrode sensors. Function blocks are implemented as part of the corresponding electronic boards. The two electrodes on the endotracheal tube are located at an angle of approximately 120 ° to each other, with iridium oxide as the coating of the electrodes. On the front panel there is a mode switch for individual stimulation pulses or bursts of stimulation pulses, a volume control for the sound indicator of nerve identification with automatic shutdown when the active electrode is removed from the controlled area, a light indication of nerve identification and / or excitation of muscle tissue at the touch point of the probe and / or the end of time stimulation with automatic shutdown when the active electrode is removed from the controlled area, light indication of precise balancing electrodes of the endotracheal tube in the middle of the vocal cords. 3 s.p. f-ly. 2 ill.

Description

The utility model relates to medical devices for examining and diagnosing a patient using electric current by measuring the electrical conductivity or resistance of a part of the patient’s body, specifically in endocrine thyroid surgery to detect and monitor the motor nerves of the vocal cords, which are at increased risk of damage during surgery.

State of the art

Currently, in Russia and abroad, the rapid development of endocrine surgery is noted, the number of operations on the thyroid gland is steadily growing. Among the specific complications after thyroid surgery, damage to the recurrent nerve is most common, which inevitably leads to impaired phonation and a change in the timbre of the voice. The only and reliable way to prevent damage to the recurrent nerve during surgery is to detect it and clearly identify it. In some cases, identifying the recurrent nerve can be quite difficult, for example: with thyroid cancer, diffuse toxic goiter, recurrent goiter, etc.

From domestic sources of patent information, there is a known method for diagnosing the function of the recurrent laryngeal nerves for the prevention of intraoperative damage by electro-acupuncture diagnostics, characterized in that active electrodes are installed at certain acopuncture points, and passive on the palmar surface of the left hand and the electric potential is recorded before and during surgery and a decrease in electric potential at a point of more than 2 mA indicates capture by the clamp or ligature of the return laryngeal nerve and the possibility of its subsequent damage.

/ published patent application of the Russian Federation No. 98111216/14 from 1998.06.15, publ. 2000.04.10 /

This method involves the use of a rather complicated electro-puncture technique with the measurement of electrical potentials at specific acopuncture points.

Another principle of nerve search during the operation is possible - detection of the recurrent nerve by detecting the appearance of an electrical signal from the vocal cords when the stimulating signal is directly applied to the recurrent nerve.

With such a principle of operation, devices of the Neurosine 100, Neurosine 400, Neurosine 800 series of Inomed companies (Germany), Magstim (England), the Medtronic neuromonitor have recently appeared abroad (England, Germany) Xomed. Inc. ”, allowing during the operation on the thyroid gland to clearly determine the location of the recurrent nerve and, thereby, avoid damage to it.

The use of these devices is absolutely shown in the following cases:

- with recurrent, diffuse toxic goiter, thyroid cancer and some other cases when the identification of the recurrent nerve is difficult;

- when training novice surgeons to operate on the thyroid gland. Technical and advertising information about these devices is publicly available both in English (for example, the website http://www.magstim.com, the page "Procedure Sheets for use with the Neurosign 100 Nerve Monitor"), and Russian-language websites of foreign countries manufacturers and distributors of their neuromonitors, for example:

Neuromonitors of the Neurosign series are designed to monitor the pathways of the motor nerves that are at increased risk during surgery in the skull, neck (including the thyroid gland) and spinal cord. Surgery in the nerve zone causes associated contractions of the motor groups of muscles. Using this, monitoring of the motor nerve pathways is carried out indirectly by monitoring and clearly interpreting muscle activity, which is recorded by means of needle electrodes introduced into these muscles. In response to the associated contractions of the motor muscle groups, the Neurosine 100 monitor emits a distinctive sound signal whose strength level is proportional to the irritation experienced by the nerve. The sound signal is perceived by the head phones (headphones). Neurosine 400, in contrast to the Neurosine 100 monitor, in response to the associated contractions of the motor muscle groups, not only emits a distinctive sound signal whose strength level is proportional to the irritation experienced by the nerve, but also displays these signals graphically on an electroluminescent display.

/ Internet address: http://medprom.ru/medprom/68507, published January 7, 2004 /. Similar information is also provided at the Internet address: http://www.conus.ru/newmed. Date of publication of information: 02/04/2004.

The Internet address www.conus.ru provides information on the specific technical characteristics of the Neurosine-100 and Neurosine-400 devices, published in 2003:

Technical characteristics of the surgical neuromonitor “Neurosine 100” (Magstim (Magstim), England): Sensors A bipolar sensor is required. Stimulation output: DC 50 μA ... 5 mA. Stimulation frequency: 30 or 3 Hz. Waveform: 200 μs pulse width, negative pulse feed. Sterilization of sensors: Autoclave, gas or chemical sterilization for reusable sensors; also available for non-sterile disposable sensors. Electrodes: Disposable. Sterile, needle electrodes; flexible polyester substrate, laryngeal electrodes Reusable. Uninsulated stainless steel needle electrodes. Sterilized in the appropriate department. Amplifier 2-channel Frequency range from 10 Hz to 10 kHz ± 3 dB Sound compression ratio: 10: 1 Loudspeaker: 6.5 inches (165 mm) Output power: 14 W Display Bar indicator; double 20 segment logarithmic. Range: 30 μV to 20 mV from peak to peak Indicators: Turns on and off the 1st and 2nd channels. Artifact level indicators of the 1st and 2nd channels. Stimulation current, CURRENT CONFIRM indicator. Control Switch for stimulation frequency (30 Hz and 3 Hz). Stimulation current control. Speaker volume control. Headphone volume control. Two switches (on / off) of the amplifier. Switch (on / off) channel identifier. Output ports. Dual EMG output: amplification up to 500 Headphone jack> 16 Ohm impedance. Maximum stimulation current: 1V / mA to download data. Power supply: 230-240 / 100-120 V, alternating current 50-60 Hz; 50 VA. Dimensions: 290 × 260 × 100 mm. Weight: 6 kg

Technical characteristics of the Neurosine 400 surgical neuromonitor (Magstim (Magstim), England): Power supply: 230 V ~ 50/60 Hz 100 VA Stimulator: direct current from 0.05 to 5 mA in steps of 0.05 mA; DC voltage from 0.05 to 5 V in 0.05 V increments Sensors: mono- and bipolar reusable; monopolar disposable. Preamplifier: analog, output voltage range 10 V (peak-to-peak); 4 channels; input signal: from 5 μV to 10 mV peak frequency band: from 10 Hz ... 5 kHz ± 3 dB noise: <10 mV peak-peak output gain: 477 Main unit: sound: 14 W, RMS displays: electroluminescent 125 × 95 mm; 320 × 240 pixels bar indicator range: 30 μV - 30 mV (peak to peak) bar resolution: 18 segments, logarithmic amplitude range: ± 25 μV, ± 50 μV, ± 100 μV, ± 250 μV, ± 500 μV , ± 1 mV, ± 2.5 mV, ± 5 mV error in measuring the amplitude of the signal: ± 10% error in setting the cursor for measuring the amplitude: ± 10 μV

or ± 2% of the scale setting resolution of the amplitude cursor: ± 10 μV range of the time sweep of the wave-like signal: 2.5; 5.0; 10, 20, 40 ms / division Time measurement error: ± 2% Time cursor error: ± 50 μV or ± 2% of scale setting Time cursor resolution: ± 50 μs Signal detection frequency: 20 kHz / channel Signal detection frequency: 20 kHz / channel control system: analog audio channel, microprocessor control system Input and output signals: input signals: preamplifier, external trigger, mute sensor output signals: stimulator, external EMG signals Physical parameters: dimensions: 340 × 210 × 140 mm weight: 8 kg

However, these devices are difficult to use without additional complex automation of their work and cost from 10 to 20 thousand US dollars.

In Russia, analogues of existing foreign devices are unknown to the authors of the proposed utility model, and the proposed utility model has obvious signs of novelty.

Solved technical problems in the proposed utility model - improving security and simplifying the operation of the device, reducing the preoperative and operational time of work with the device.

Utility Model Essence

Achievable technical result is provided by means of additional automation of the device, as well as the organization of the formation of stimulating signals. At the same time, the main differences of the proposed utility model from analogues that provide advantages are as follows:

- automatic change of stimulating signal parameters during monitoring of the motor nerve, from the minimum value and in the direction of its increase to the maximum allowable, which ensures complete safety not to subject the patient to electric shock during surgery. In analogs, the parameters of the stimulating signal are changed manually using the switches and monitoring the set value by indicators, as well as a set of menu options;

- there are no organs for presetting the parameters of the stimulating signal on the front panel of the device, which, unlike analogs, reduces the preparation time for the device and simplifies working with it;

- no additional instruments and devices are required when searching for the recurrent nerve. When using analogs, a device for measuring the impedance (impedance meter) is required. Assessment of the position of the endotracheal tube in relation to the vocal

ligaments provided by the proposed device. Provides automatic control of the position of the tube in relation to the vocal cords during the operation.

- the maximum exposure time to the motor nerve with a stimulating signal does not exceed 1 second, which automatically avoids nerve fatigue. In analogues, the responsibility for the time of exposure to the nerve lies entirely with the surgeon;

- automatic removal (disconnection) of the stimulating signal from the active electrode is provided in case of occurrence (excitation) of muscle artifacts when the electrode comes into contact with muscle tissue.

- separate power supply of the device - from batteries (accumulators), independent of mains power supply in order to ensure the safety of working with the device;

Unlike analog devices, when working with which nerve detection is carried out by medical personnel according to the sound tone, in the proposed neuromonitor, the return nerve is detected by the appearance of a signal from the electrodes of the endotracheal tube by hardware (memory devices, comparisons, etc.).

In essence, the proposed neuromonitor of the recurrent nerve is characterized by the presence of the following structural elements: a stimulating active electrode in the form of a search probe with a signal sensor, a neutral passive electrode installed on the patient-monitoring object, an endotracheal tube with sensor electrodes, a control unit and signal generation with the following functional blocks in its composition, known from a special reference public literature, namely: a pulse generator for pho a stimulator extender for the active electrode and a modulation current driver for a passive electrode, a pulse generator for a time interval shaper, a stimulation pulse modulator, four amplifiers, four differential amplifiers, three half-wave rectifiers, four low-pass filters, four peak detectors, six sampling and storage devices, four comparison devices, two counters, four indicators: three light and one sound, located at the outputs of h tyreh chains signal electrodes sensor processing units.

These blocks are connected to each other as follows: the first output of the first generator is connected to the input of the stimulator former, the output of which is connected to the active probe electrode. The second output of the first generator is connected to the input of the modulation current driver, the output of which is connected to a passive electrode. The input of the pulse shaper is connected to the output of the second generator, and the output

a shaper of temporary pulses to the input of the stimulation pulse modulator, the output of which is connected to the control input of the shaper of the stimulus.

Two signal lines of the signal sensor of the active probe electrode are connected to the inputs of two amplifiers, the outputs of which are connected to the corresponding inputs of the differential amplifier of the first block chain, consisting after the specified differential amplifier from a half-wave rectifier, low-pass filter, peak detector, first sampling-storage device, output which is connected to the input of the second sampling-storage device, the second differential amplifier of the output signals of these sampling-storage devices . The output of the second differential amplifier is further connected to the continuation of the first chain in the form of a comparison device, a counter and at the output of the first chain of the indicator light.

The second block chain after the input of its low-pass filter is connected to the output of the third differential amplifier of the output signals of the amplifiers of the electrode sensors of the endotracheal tube, then in the second block chain after the low-pass filter, a peak detector, two serial sampling and storage devices, and a fourth differential amplifier of the output signals of these sampling devices -storage, comparison device, counter and the output of the second chain of an audio indicator.

The third and fourth identical sequential block chains consist of the same rectifiers, low-pass filters, peak detectors, sample-storage devices, comparison devices, and light indicators, respectively. The input of the third chain is connected to the output of the amplifier of the first endotracheal tube sensor involved in the second chain, the input of the fourth chain is connected to the output of the amplifier of the second endotracheal tube sensor involved in the second chain.

The stimulation pulse modulator is equipped with outputs for zeroing amplifiers at the moment of passage of the stimulation signal, outputs for zeroing peak detectors in refractory periods (control inputs for resetting the corresponding blocks to avoid excessive complication of the circuit diagram are not shown in the figure). The low-pass filter output of the first block chain is connected to the control input of the modulator for the resolution signal generated when the probe electrode touches the object. The outputs of the counters of the first and second chains of blocks are connected to the control inputs of the modulator to stop its operation by signals generated at the time of nerve detection and / or when

excitation of muscle tissue at the touch point of the probe electrode and / or at the end of the stimulation time.

Function blocks are implemented as part of the corresponding electronic boards:

boards with two amplifiers, rectifiers and low-pass filters of signals from the endotracheal tube electrodes, a differential amplifier of the difference signal of the endotracheal tube electrodes with a rectifier and a low-pass filter;

boards for amplifiers of the probe signals, an amplifier of the difference signal coming from the probe signal sensor, composed of a rectifier and a low-pass filter, a peak detector, a sampling-storage device;

memory boards for analog signals with three peak detectors, sampling-storage devices, a device for isolating a difference signal when a stimulation signal changes, a device for extracting a difference signal from a probe electrode signal sensor to detect interference when muscle tissue is excited in the touch zone of the probe electrode;

a stimulation signal generation board with a pulse generator, a voltage-current transformer of the stimulation signal, a voltage-current transformer of the modulation signal of the detected signal from the endotracheal tube electrodes;

stimulation signal modulation board with a device for generating pulse durations and bursts of pulses, an eight-bit multiplexer-switch of analog signals; boards of comparison devices with voltage followers, reference signal conditioners and comparators for generating control and indication commands;

control boards with a periodic signal generator and a shaper of time intervals.

Two electrodes on the endotracheal tube are located at an angle of 120 ° to each other, with iridium oxide as an electrode coating to increase the capacitance of the vocal cord - electrode junction.

On the front panel of the neuromonitor’s device there are sockets for docking cables of electrodes with a control unit, an on / off switch for battery or accumulator power supply with corresponding indication, a switch for individual stimulation pulses or bursts of stimulation pulses,

volume control of a sound indicator of nerve identification with automatic shutdown when the active electrode is withdrawn from the controlled area, light indication of nerve identification and / or excitation of muscle tissue at the touch point of the probe and / or completion of the stimulation time with automatic shutdown when the active electrode is removed from the controlled area, light indication precise balancing of the position of the endotracheal tube electrodes in the middle of the patient’s vocal cords.

List of figures

Figure 1 is a functional block diagram of a device;

Figure 2 - arrangement of elements on the front panel of the neuromonitor.

Information confirming the feasibility of implementing the utility model. In Fig. 1, the numbers indicate the following structural elements and blocks: a stimulating active electrode in the form of a search probe 1 with a signal sensor 2, a neutral passive electrode 3 installed on the monitoring object, an endotracheal tube with sensor electrodes 4, 5, a pulse generator 6 for the stimulus driver 7 for the active electrode and a modulation current driver 8 for the passive electrode, 9 pulse generator for the driver 10 time slots, module torus 11 stimulation pulses, four amplifiers 12-15, four differential amplifiers 16-19, three rectifiers 20-22 half-wave, four low-pass filters 23-26, four peak detectors 27-30, six sampling and storage devices 31-36, four comparison devices 37-40, two counters 41.42, four indicators: three light 43-45 and one sound 46.

All the blocks — purchased items known from the technical manuals, are built into the electronic circuit boards of the control unit of the neuromonitor of the recurrent nerve with the abbreviation “NMVN-01”, and, therefore, the proposed utility model meets the requirements of the criterion of “industrial applicability”.

Composition of boards: - board of the amplifier of detected signals from the electrodes of the endotracheal tube; - A board of amplifiers for probe signals; - board memory analog signals; - stimulation signal generation board; - stimulation signal modulation board; - comparator board; - control board with a periodic signal generator and a shaper of time intervals; - source of power.

The amplifier board of the detected signals from the electrodes of the endotracheal tube is:

- two amplifiers, with rectifiers and low-pass filters (fprop. = 0 ... 10 kHz, Ku = 1.59), signals coming from the left and right electrodes (fprop. = 0 ... 10 kHz, Ku = 32 );

- differential amplifier of the difference signal (Ku = 20) with a rectifier and a low-pass filter (fппп = 0 ... 10 kHz, Ku = 1,59);

The probe signal amplifier board is:

- amplifier of the difference signal coming from the probe, consisting of a rectifier and a low-pass filter (fpro. = 0 ... 10 kHz, Ku = 636);

- peak detector;

- sampling-storage device;

The memory board for analog signals is:

- three peak detectors (storing peak values of the detected signal);

- sampling-storage devices;

- a device for detecting changes in the detected signal (differential signal) when changing the level of the stimulation signal;

- a device for extracting a differential signal from the probe electrode for fixing interference (excitation of muscle tissue) in the touch zone of the probe electrode. The stimulation signal generation board is:

- a pulse generator with a frequency (fgen. = 100 kHz ± 10%);

- voltage-current converter stimulation signal;

- a voltage-current converter modulating the detected signal from the electrodes of the endotracheal tube.

The stimulation signal modulation board is:

- a device for generating the duration of pulses and bursts of pulses (Timp. = 100 μs., 200 μs., 300 μs., 400 μs.);

- eight-digit multiplexer (switch) of analog signals (the formation of the amplitude of a pulse or a pack of current pulse 1 amp. = 0.2 ... 1.6 mA);

The comparator board is a voltage follower, reference signal conditioners, and comparators for generating control and indication commands.

The control board with a periodic signal generator and a shaper of time intervals is:

- a generator of periodic signals with a frequency f = 30 ± 10% Hz;

- shaper of time intervals: T = 50 μs., 100 μs., 200 μs., 300 μs., 400 μs., 1.2 ms, 1.0 sec.

Power source - battery power (or batteries) ± 6V; ± 18V.

Medical and technical characteristics of the device, ensuring the safety of working with the patient: Electrode materials in contact with the patient’s body do not have toxic and / or allergic effects on him and do not cause irritation of the tissues surrounding the electrode. It is possible to expose the electrodes to multiple (at least 10 times) steam sterilization at a temperature of 134 ° C to 140 ° C. The electrodes during operation are resistant to biological fluids and body tissues at a temperature of 32 to 42 ° C. The electrodes are resistant to pre-sterilization cleaning and chemical sterilization methods. The device is safe for medical personnel and the patient from receiving electric shock in case of violation of insulation. The device does not lead to fatigue of motor nerves during their direct stimulation.

Technical characteristics of the proposed device:

Characteristics of the motor nerve stimulation signal:

Stimulation signal in the form of negative impulses:

- the pulse frequency is f = 30 ± 10% Hz;

- pulse duration - 100, 200, 300, 400 μs .;

- the amplitude of the pulses is 0.2; 0.4; 0.6; 0.8; 1.0; 1,2; 1.4; 1.6 mA (discreteness - 8 values for each of the above pulse durations). Stimulation signal in the form of bursts of pulses:

- repetition rate of bursts of pulses - f = 30 ± 10% Hz;

- the duration of the bursts of pulses is 100, 200, 300, 400 μs .;

- the amplitude of the bursts of pulses is ± 0.2; ± 0.4; ± 0.6; ± 0.8; ± 1.0; ± 1.2; ± 1.4; ± 1.6 mA (discreteness of -8 values for each of the above pulse train durations);

- the frequency of filling the packs with pulses - f = 100 ± 10% kHz.

Note. The choice of stimulation signal is determined by the position of the switch on the front panel of the device in figure 2

The number of pulses or bursts of pulses of exposure for one touch on living tissue in the area of the motor nerve search is 32.

The duration of exposure to pulses or packs of pulses per touch on living tissue in the area of the motor nerve search is no more than 1 second.

Duration of the refractory period (time of suppression of artifacts - noise interference):

- during stimulation with negative impulses - 1.2 ... 1.25 ms;

- when stimulated by bursts of pulses - 50 μs. Characteristics of the detected (input) signals:

- the amplitude of the signals is 5 μV ... 50 mV:

- frequency band - 0.1 Hz ... 10 kHz;

- waveform - damped oscillations. The number of measurement channels is two. Indicators and switching bodies:

- switch on / off the device;

- light indication of power on;

- light indication of the balancing position of the electrodes of the endotracheal tube relative to the vocal cords (LEDs - "G. St. Lev."; "G. St. right."; "Balance");

- a light indication of the occurrence of excitation of muscle artifacts when the electrode comes into contact with muscle tissue (it turns off when the active electrode is removed from the controlled area);

- a sound indication of the identification of the motor nerve (should be turned off when the active electrode is removed from the controlled area). The mass of the device is not more than 1 kg (with the mass of the mentioned analog devices 6 ... 8 kg). Terms of Use:

- temperature range in operating mode from 10 to 40 ° C;

- relative humidity from 30% to 80%;

- storage temperature from - 5 to + 30 ° С;

- atmospheric pressure from 60 to 106 kPa.

Principle and method of work

The main features of the proposed device

When the device is turned on and the electrodes are pre-installed for the patient, a weak electrical stimulation signal with frequency f = 100 kHz and current I = 50 μA is supplied between the neutral (passive) electrode and the electrodes of the endotracheal tube. This allows:

- transmit signals from the electrodes of the endotracheal tube and the probe electrode, by modulation-demodulation method, at a remote distance - to the neuromonitor control unit (about 3 m), without the use of a preliminary amplifier;

- carry out the installation of the endotracheal tube in relation to the vocal cords without the use of additional impedance measuring devices;

- automate the process of interrogation and detection of the recurrent nerve.

Stimulation by an electric signal in the form of pulse packets modulated with a frequency f = 100 kHz with a frequency f = 30 Hz of positive - negative polarity is provided. This leads to a decrease in the time of depolarization of the patient’s living tissues and, therefore, reduces the duration of the refractory period (time of suppression of artifacts - noise interference). Reducing the refractory period allows you to fix the signals - the reaction of the vocal cords with lower values of the stimulation signal.

Measurement of weak electrical signals of “excitation” of living tissues in the immediate vicinity of the touch point of the probe electrode is provided. When these signals are detected, the stimulation process at a given point is terminated. The procedure for working with a device that implements a utility model of the device

With the device they work as follows.

To work with the device "NMVN-01", during the surgical operation, it is necessary to install an endotracheal tube and a neutral electrode in the patient. With the “PIT” switch on the “NMVN-01” front panel, turn on the power to the device, and the “PIT” LED should light up. After turning on the power of the device through the patient, between the neutral electrode and the electrodes of the endotracheal tube, an alternating current of 100 kHz (meander) with an amplitude of not more than 50 μA will be passed from the current source of the device.

By turning the endotracheal tube, the LEDs light up. St. Leo. "," G. St. rights. ”and the“ Balance ”LED. These actions allow you to get equal transient resistance (impedance) between each of the vocal cords and the electrode of the endotracheal tube. After that, you can begin to search for the return electrode using the probe electrode.

When the probe electrode touches the living tissue of the patient in the area of the search for the return nerve (during the operation), an enable signal is generated. By the Resolution signal, a stimulation signal is sent to the point of contact. The stimulation signal in the form of negative current pulses (bursts of pulses) automatically changes discretely in amplitude and duration in the sequence:

1. 0.2; → 0.4; → 0.6; → 0.8; →, 0; → 1.2; → 1.4; → 1.6 mA with a duration of 100 μs;

2. 0.2; → 0.4; → 0.6; → 0.8; → 1.0; → 1.2; → 1.4; → 1.6 mA with a duration of 200 μs;

3. 0.2; → 0.4; → 0.6; → 0.8; → 1.0; → 1.2; → 1.4; → 1.6 mA with a duration of 300 μs;

4. 0.2; → 0.4; → 0.6; → 0.8; → 1.0; → 1.2; → 1.4; → 1.6 mA with a duration of 400 μs.

Notes:

1. The permission signal is removed after the electrode is removed from the patient’s living tissue;

2. the error of the amplitude values of the stimulating signal from the above is ± 10%;

3. the error in the values of the duration of pulses or bursts of pulses from the above is ± 10%;

The maximum number of pulses (bursts of pulses) of the stimulating signal passing in one touch is 32, the frequency of the discrete values is f = 30 ± 10% Hz. The maximum stimulation time for one touch is no more than 1 second.

When a detectable signal from the electrodes of the endotracheal tube appears, which corresponds to the identification (detection) of the recurrent nerve, the further growth of the stimulating signal in amplitude and duration stops. When a detected signal appears, the NMVN-01 neuromonitor generates an audio signal that signals the detection of a return nerve. The sound signal stops after the probe electrode is removed from the place of contact with the return nerve.

When muscle tissue is excited in the immediate vicinity of the probe electrode, the “Interference” LED on the front panel of the device lights up, while the stimulation signal is stopped. The probe electrode should be removed from the point of contact with the living tissue of the patient. The “Interference” LED goes out after the probe electrode is removed from the point of contact with the patient’s live tissue.

After completing work with the NMVN-01 device, the PIT switch on its front panel must be turned off.

Thus, the neuromonitor of the recurrent nerve, designed to monitor the motor nerves of the vocal cords, at an increased risk of damage during surgery:

- with repeated operations on the thyroid gland;

- with large volumes of the thyroid gland and diffuse toxic goiter;

- with thyroid cancer, when it is necessary to remove not only the thyroid gland, but also the lymph nodes with fatty tissue;

- It can be used as a teaching aid when teaching young doctors operations on the thyroid gland in medical universities, research institutes and clinics, it has qualitatively better technical and economic characteristics compared to well-known analogues.

Claims (4)

1. The neuromonitor of the recurrent nerve, characterized by the presence of the following structural elements: electrodes in contact with the monitoring object: a stimulating active electrode in the form of a search probe with a signal sensor, a neutral passive electrode, sensor electrodes of the endotracheal tube; a control and signal generation unit with the following functional units: a pulse generator for a stimulus generator for an active electrode and a modulation current generator for a passive electrode, a pulse generator for a time interval generator, stimulation pulse modulator, four amplifiers, four differential amplifiers, three half-wave rectifiers , four low-pass filters, four peak detectors, six sample-storage devices, four comparison devices, two counters, four indicators: three light and one sound, located at the outputs of four chains of signal processing units of the electrode sensors, the blocks being connected to each other as follows: the first output of the generator is connected to the input of the stimulator, the output of which is connected to the active electrode - probe, the second output of the generator is connected to the input of the modulation current driver, the output of which is connected to the passive electrode, the output of the second generator is connected to the input of A time pulse output is connected to the input of the stimulation pulse modulator whose output is connected to the control input of the stimulus; two signal lines of the signal sensor of the active probe electrode are connected to the inputs of two amplifiers, the outputs of which are connected to the corresponding inputs of the differential amplifier of the first block chain, consisting sequentially after the differential amplifier from a half-wave rectifier, a low-pass filter, a peak detector, a sampling-storage device, the output of which connected to the input of the second sample-storage device, and a second differential amplifier of the output signals of these sample-storage devices, the output of the second differential amplifier is further connected to the continuation of the first chain of blocks in the form of a comparison device, a counter and at the output of the first chain of the light indicator; the second block chain with the input of its low-pass filter is connected to the output of the third differential amplifier of the output signals of the signal amplifiers of the sensor electrodes of the endotracheal tube, then in the second block chain after the low-pass filter there is a peak detector, two serial sampling-storage devices, and a fourth differential output signal amplifier devices, a comparison device, a counter, and an audio indicator at the output of the second chain; the third and fourth identical block chains, consisting respectively of rectifiers of low-pass filters, peak detectors, sampling and storage devices, comparison devices, light indicators, the input of the third chain is connected to the output of the amplifier involved in the second chain, the input of the fourth chain is connected to that used in the second chain amplifier output; the stimulation pulse modulator is equipped with outputs for amplifying the amplifiers at the time of passage of the stimulation signal, outputs for zeroing the peak detectors in refractory periods, the output of the low-pass filter is connected to the control input of the modulator for the resolution signal generated when the probe electrode touches the object, the outputs of two counters are connected to the control inputs modulator for stopping the operation of the modulator by signals generated at the moment of detection of a nerve and / or upon excitation of muscle tissue at the point of contact of the electron probe genus and / or at the end of the stimulation time. 2. The neuromonitor according to claim 1, characterized in that the functional blocks are implemented as part of the corresponding electronic boards, namely: boards with two amplifiers, rectifiers and low-pass filters of signals coming from the endotracheal tube electrodes, a differential amplifier of the difference signal of the endotracheal tube electrodes with rectifier and low pass filter; boards for amplifiers of the probe signals, an amplifier of the difference signal coming from the probe, consisting of a rectifier and a low-pass filter, a peak detector, a sampling-storage device; memory boards for analog signals with three peak detectors, sampling and storing devices, a device for isolating a difference signal when a stimulation signal changes, a device for extracting a difference signal from a probe electrode to detect interference when muscle tissue is excited in the touch zone of the probe electrode; stimulation signal generation boards with a pulse generator, a voltage-current converter for stimulation signal, a voltage-current converter for converter of a modulation signal of a detected signal from the endotracheal tube electrodes; stimulation signal modulation board with a device for generating pulse durations and bursts of pulses, an eight-bit multiplexer-switch of analog signals; boards of comparison devices with voltage followers, reference signal conditioners and comparators for generating control and indication commands; control boards with a periodic signal generator and a shaper of time intervals. 3. The neuromonitor according to claim 1, characterized in that the two electrodes on the endotracheal tube are located at an angle of about 120 ° to each other, with iridium oxide as the coating of the electrodes. 4. The neuromonitor according to claim 1, characterized in that on its front panel there are sockets for connecting the electrode cables to the control unit, an on / off switch for battery or battery power supply with appropriate indication, a mode switch for individual stimulation pulses or bursts of stimulation pulses, volume control of the sound indicator of nerve identification with automatic shutdown when the active electrode is withdrawn from the monitored area, light identification indication is not va and / or excitation of the muscle tissue at the point of touch probe and / or completion time of stimulation with automatic tripping when retracting the active electrode from the controlled area, light indication precision balancing electrode position endotrahialnoy middle tube vocal cords.