High frequency electric current. Hardening of metals by high frequency currents. Contraindications to employment with high currents are

High frequency currents (HFC) are considered to be currents for which the quasi-stationarity condition is not satisfied, which results in a strongly pronounced skin effect. For this reason, it flows along the surface of the conductor without penetrating into its volume. such currents exceed 10,000 Hz.

To obtain currents with a frequency of more than several tens of kilohertz, electric machine generators are used, which include a stator and a rotor. On their surfaces facing each other there are teeth, due to the mutual movement of which a pulsation of the magnetic field occurs. The resulting output current is equal to the product of the rotor speed and the number of teeth on it.

Also, to obtain HDTV, oscillatory circuits are used, for example, an electric circuit, which includes inductance and capacitance. To obtain HDTV frequencies in billions of hertz, installations with a hollow oscillatory circuit (BWO, TWT, klystron) are used.

If a conductor is placed in a magnetic field of a coil in which a high frequency flows, then large eddy currents will arise in the conductor, which will heat it up. The temperature and intensity of heating can be adjusted by changing the coils. Due to this property, HDTV is used in many areas of human activity: in induction furnaces, in metallurgy for surface hardening of parts, medicine, agriculture, in household appliances (microwave ovens, various cooking devices), radio communications, radar, television, etc.

Examples of using high frequency currents

With the help of HFC in induction furnaces, you can melt any metal. The advantage of this type of smelting is the possibility of smelting under full vacuum conditions, when contact with the atmosphere is excluded. This makes it possible to produce alloys that are pure in terms of non-metallic inclusions and unsaturated with gases (hydrogen, nitrogen).

On hardening machines with the help of HFC, it is possible to harden steel products only in the surface layer due to the skin effect. This makes it possible to obtain parts with a hard surface that can withstand significant loads and at the same time without reducing wear resistance and ductility, since the core remains soft.

In medicine, high-frequency currents have long been used in UHF devices, where heating of a dielectric is used to heat up any human organs. HFCs of even very high amperage are harmless to humans, since they flow exclusively in the most superficial layers of the skin. Also used in medicine are electric knives based on HDTV, with the help of which blood vessels are “welded” and tissues are cut.

Submerge the stick in the pond. The water level should rise. But this increase is so negligible that it is difficult to detect it. And if you alternately immerse a stick in water and pull it out, then waves will run through the water. They are noticeable at a considerable distance from the place of origin. This mechanical movement of water can be compared to electromagnetic phenomena. A constant electromagnetic field is generated around a constant current conductor. It is difficult to find it far from the current-carrying conductor.

But if an alternating electric current is passed through the conductor, then the electromagnetic forces around the conductor will change all the time, that is, the electromagnetic field around it will be agitated. Electromagnetic waves run from an alternating current conductor.

The distance between the two nearest wave crests on a pond is the wavelength. It is denoted by the Greek letter λ (lambda). The time during which any part of the waving water surface rises, falls and returns to its initial position - this is the period of oscillation - T... The reciprocal is called the vibration frequency and is denoted by the letter f... The vibration frequency is measured in periods per second. The unit for measuring the frequency of oscillations, corresponding to one period per second, is named hertz (hertz) - in honor of Heinrich Rudolf Hertz (1857 - 1894), the famous researcher of oscillations and waves (1,000 hertz \u003d 1 kilohertz, 1 million hertz \u003d 1 megahertz) ...

Wave speed ( from) is the distance the waves propagate in one second. During one period T, the wave motion has time to propagate exactly to the length of one wave X. For wave motion, the following relations are valid:

with T \u003d λ; s / f \u003d λ

These relationships between vibration frequency, wavelength and wave velocity are true not only for water waves, but also for any vibrations and waves.

It is necessary to immediately emphasize one property of electromagnetic oscillations. When they propagate in empty space, then, whatever their frequency, whatever the wavelength, the speed of their propagation is always the same -300 thousand km / sec. Visible light is one of the types of electromagnetic oscillations (with a wavelength of 0.4 to 0.7 nanometers and a frequency of 10 14 - 10 15 Hz). The speed of propagation of electromagnetic waves is the speed of light (3 10 10 cm / sec).

In air and other gases, the speed of propagation of electromagnetic oscillations is only slightly less than in void. And in various liquid and solid media, it can be several times less than in a void; moreover, here it depends on the vibration frequency.

Radiation and emitters

We live in a world of electromagnetic waves. And sunlight, and the mysterious streams of cosmic rays falling on the Earth from interstellar space, and the heat emitted by a hotly heated furnace, and the electric current circulating in power networks - all these are electromagnetic oscillations. All of them propagate in the form of waves, in the form of rays.

Any object, any body that generates waves is called an emitter. The stick that is dangled in the pond is the emitter of water waves. Water resists its movement. It takes power to move a stick. This power transmitted to water is numerically equal to the product of the square of the speed of movement of the stick by the resistance to movement. Part of this power turns into heat - it goes to heating the water, and partly goes to the formation of waves.

We can say that the total resistance experienced by a stick is the sum of two resistances: one of them is the resistance to heat generation, and the other is the resistance to wave formation - the resistance to radiation, as it is commonly called.

The same patterns are observed in electromagnetic phenomena. The power that the electric current consumes in a conductor is equal to the product of the conductor's resistance by the square of the current in it. If we take the current in amperes, and the resistance in ohms, then the power will be obtained in watts.

In the electrical resistance of any conductor (as in the mechanical resistance of water to the movement of a stick), two components can be distinguished: resistance to heat generation - ohmic resistance and resistance to radiation - resistance caused by the formation of electromagnetic waves around the conductor that carry away energy.

Take, for example, an electric hotplate with an ohmic resistance of 20 ohms and a current of 5 amps. The power converted into heat in this tile will be equal to 500 W (0.5 kW). To calculate the power of the waves traveling from the emitter, you need to multiply the square of the current in the conductor by the radiation resistance of this conductor.

Radiation resistance is complexly dependent on the shape of the conductor, on its size, on the length of the emitted electromagnetic wave. But for a single rectilinear conductor, at all points of which there is a current of the same direction and the same strength, the radiation resistance (in ohms) is expressed by a relatively simple formula:

R rad \u003d 3200 (l / λ) 2

Here l is the length of the conductor, and λ is the length of the electromagnetic wave (this formula is valid when l significantly less than λ ).

For rough estimates, this formula can be used for any electrical structures, any machines and devices, for example, for a heating plate, in which the wire is not straight, but coiled into a spiral laid in a zigzag. But as l it is necessary to substitute not the full length of the conductor in the formula for the radiation resistance, but one of the given dimensions of the structure under consideration. For hot plate l approximately equal to the tile diameter.

Central power plants generate alternating current with a frequency of 50 Hz. This current corresponds to an electromagnetic wave 6 thousand km long. Not only an electric stove, but also the largest electrical machines and apparatus and even long-distance power lines are sized l many times smaller than the length of this electromagnetic wave. The radiation resistance of the largest electrical machines and apparatus for a current with a frequency of 50 Hz is measured in negligible fractions of an ohm. Even at currents of thousands of amperes, powers of less than one watt are emitted.

Therefore, in practice, when using an industrial current with a frequency of 50 Hz, it is not necessary to take into account its wave properties. The energy of this current is firmly "tied" to the wires. To connect the consumer (lamps, furnaces, motors, etc.), direct contact with the current-carrying wires is required.

With an increase in the frequency of the current, the length of the electromagnetic wave decreases. For example, for a current with a frequency of 50 MHz it is equal to 3 m. With such a wave, even a small conductor can have significant radiation resistance and, at relatively low currents, emit significant amounts of energy.

According to refined calculations, a conductor with a length of half a wave (l \u003d λ / 2) has radiation resistance R ex. about 73 ohms. With a current of, say, 10 A, the radiated power would be 7.3 kW. A conductor capable of emitting electromagnetic energy is called an antenna. This term was borrowed by electricians at the end of the last century from entomology - an antenna is called an antenna-tentacle in insects.

At the origins of radio engineering

Electromagnetic vibrations occurring at a frequency of a million billion hertz, our vision perceives as light. A thousand times slower vibrations can be felt by the skin as heat rays.

Electromagnetic vibrations, the frequency of which ranges from several kilohertz to thousands of megahertz, are not perceived by the senses, but they are of great importance in our life. These vibrations are capable of propagating, like light and heat, in the form of rays. In Latin, the word "ray" is "radius". From this root the word "radio waves" is formed. These are oscillations generated by high frequency currents. Their main, most important application is wireless telegraph and telephone communications. For the first time in the world, the wireless transmission of signals by radio waves was practically carried out by the Russian scientist Alexander Stepanovich Popov. On May 7 (April 25), 1895, at a meeting of the physics department of the Russian Physicochemical Society, he demonstrated the reception of radio waves.

Nowadays, with the help of radio, you can establish a wireless connection between any parts of the world. New branches of high-frequency technology have emerged - radar, television. Radio engineering began to be used in various industries.

It is right to start the review of high-frequency technology with methods of obtaining alternating currents of high frequency.

The oldest and simplest way to produce high-frequency electromagnetic oscillations is to discharge a capacitor through a spark. The first radio transmitters of A.S. Popov had spark generators with such simple spark gaps in the form of two balls separated by an air gap.

Machine current generator of increased frequency.

At the beginning of this century, improved spark gaps appeared, which gave high-frequency oscillations with a power of up to 100 kW. But there was a great loss of energy in them. Currently, there are more advanced sources of high frequency currents (HFC).

To obtain currents with a frequency of up to several kilohertz, machine generators are usually used. Such a generator consists of two main parts - a stationary stator and a rotating rotor. The surfaces of the rotor and stator facing each other are toothed. When the rotor rotates, the mutual movement of these teeth causes a pulsation of the magnetic flux. In the working winding of the generator, laid on the stator, a variable electromotive force (emf) arises. The frequency of the current is equal to the product of the number of rotor teeth and the number of its revolutions per second. For example, with 50 teeth on the rotor and its rotation speed of 50 rps, a current frequency of 2500 Hz is obtained.

At present, machine HDTV generators are produced with a capacity of up to several hundred kilowatts. They give frequencies from a few hundred hertz to 10 khz.

One of the most widespread modern methods of HDTV production is the use of oscillatory circuits connected to electrically controlled valves.

A variable is a current that periodically changes in magnitude and direction. During one oscillation, the current increases to a maximum, then drops to zero, changing the direction to the opposite, again increases to a maximum and again reaches zero.

The period of time (T) during which one oscillation occurs is called a period. The reciprocal of the period, that is, 1 / T, is called frequency. If the period

T is expressed in seconds, then frequency is the number of oscillations per second. The frequency corresponding to one vibration per second is taken as a unit and in honor of the physicist Herz it was named hertz (Hz).

If the oscillation is performed according to the sine law, then the graphical representation of the oscillatory process is a sinusoid. Such vibrations are called harmonic.

When an alternating current passes through a conductor, electromagnetic oscillations arise around the latter, propagating in space in all directions; they form electromagnetic waves. Electromagnetic waves propagate in a vacuum at the speed of light - 300,000 km / sec (3 * 10 10 cm / sec), and in various media at a slightly lower speed.

The distance that an electromagnetic wave travels during one period is called the wavelength.

Currently, electromagnetic waves of the so-called radio frequency are divided into long - 3000 m and more, medium - from 3000 to 200 m, intermediate - from 200 to 50 m, short - from 50 to 10 m, ultrashort - less than 10 liters, and the latter into meter - from 10 to 1 m, decimeter - from 1 m to 10 cm and centimeter - from 10 to 1 cm.

Currents of any frequency, including high ones, are obtained using an oscillatory circuit, which consists of a capacitor (electrical capacitance - C) and an inductance (wire coil - L, at high-frequency currents without an iron core).

If a charge is imparted to the capacitor of the oscillatory circuit, then it begins to discharge through the inductance: in this case, a magnetic field arises around it due to the energy of the current. When the capacitor is completely discharged, the current should stop, but as the current weakens, the magnetic field energy stored in the inductor is transferred back to the current in the same direction; as a result, the capacitor will be charged again, but the sign of the charge on its plates will change to the opposite. Having received a charge, the capacitor again begins to discharge through the inductance, but its discharge current will already be in the opposite direction. The passage of current through the inductance will again be accompanied by the appearance of a magnetic field, the energy of which, as the discharge current decreases, will be converted into the energy of the induced current in the same direction. The capacitor plates will be charged again, and their charge will be of the same sign as at the beginning. The energy accumulated now in the capacitor is less than the initial one, since part of it is spent on overcoming the ohmic resistance of the circuit. Going first in one direction and then in the opposite direction, the capacitor discharge current makes one oscillation.

Having received a charge again, although less than the initial one, the capacitor will again begin to discharge through the inductor. With each oscillation, the amplitude of the current will decrease. This will continue until all the energy accumulated in the capacitor is spent on overcoming the ohmic resistance of the circuit and partially on the emission of electromagnetic waves - a group of damped oscillations appears. In order for the oscillations to be low-damped or non-damped, it is necessary to periodically supply energy to the oscillatory circuit, to make up for its losses. In modern high-frequency medical devices, this is done with the help of electronic tubes used in generator circuits.

The simplest oscillator tube is a triode. It has 3 electrodes: cathode, control grid and anode. When heated, the cathode releases electrons. If a positive potential is applied to the anode and a negative potential to the cathode, then an electric field arises between the anode and the cathode, under the influence of which negatively charged electrons are attracted to the anode, which has a positive potential. Penetrating between the turns of the control grid located between the cathode and the anode, the electrons reach the anode, as a result of which current flows in the anode circuit. The control grid is located closer to the cathode and has a stronger effect on the electrons than the anode. When there is a positive potential on the control grid, the movement of electrons is accelerated - per unit time, more of them fall on the anode, the current increases; when there is a negative potential on the grid, it repels electrons, not allowing them to pass to the anode - the anode current becomes weaker.

The triode has a number of disadvantages, and this forced the transition to more advanced lamps - tetrodes, beam tetrodes, pentodes, etc. These lamps are used in medical high-frequency generators operating on self-excitation with feedback.

The anode current flowing in the generator lamp circuit charges the capacitor of the oscillating circuit, which leads to the occurrence of electrical oscillations in the anode oscillating circuit. Oscillations of the current create an alternating magnetic field in the inductance coil of the oscillatory circuit, the lines of force of which intersect the turns of the adjacent inductance coil of the control grid, inducing alternating potentials on it. As a result of this, the oscillatory circuit in the anode circuit, through the connection with the lamp grid, begins to control the anode current supplying it. This relationship is called feedback. In the presence of feedback (if you turn on the power to the generator), oscillations occur in the anode oscillatory circuit, the generator is self-excited. This is the principle of operation of the generator on self-excitation.

In practice, in devices of high and ultra-high frequency, the structure of the oscillatory circuit is much more complicated. In high-frequency devices, oscillations initially occur in a low-power master oscillator. The oscillations arising in it are usually transmitted inductively to an intermediate amplifier, and then to an output amplifier assembled on more powerful tubes. The principle of amplification is that oscillations from the previous circuit are fed to the control grids of more powerful lamps of the subsequent circuit, which leads to an increase in the oscillation power.

The therapeutic circuit, which is used for carrying out the treatment procedure, is connected to the previous circuit, which is usually an output amplifier only inductively, in order to protect the patient from the high voltage under which the previous circuits are located.

All circuits must be tuned to resonance, that is, to the same frequency. In this case, the transfer of energy from one circuit to another is carried out most completely.

Previously, spark generators were used to obtain high-frequency currents. They are currently discontinued because they do not generate a stable frequency, which creates radio interference.

Any electric current, including high-frequency, has a thermal effect. This heat arises inside the tissues, and therefore received the name endogenous as opposed to exogenous, when heat penetrates into the tissues from the outside, as it happens when exposed to therapeutic mud, paraffin, heating pad.

In order to understand the reason for the appearance of heat inside tissues at high frequency currents, it is necessary to disassemble the mechanism of their passage through the tissues. In tissue fluids and inside cells there are ions, mainly sodium and chlorine, into which the basic salt contained in the body, sodium chloride, dissociates. In addition to sodium and chlorine ions, the body also contains smaller amounts of other ions (calcium, magnesium, phosphorus, etc.), and also contains protein molecules that carry an electric charge.

In addition to charged particles, the tissues of the body contain polar molecules (dipoles), in which the electric charges inside the molecule are displaced and two poles can be distinguished - positive and negative. Dipole molecules (dipoles) include, in particular, water molecules.

When a high-frequency voltage is applied to the tissues of the body, a high-frequency electric field arises in the space between the electrodes. Under its influence, all charged particles are set in motion: negative ones are directed to the positive, positive ones - to the negative pole. Dipole molecules begin to rotate along the field so that the negative pole is directed towards the positively charged, positive - towards the negatively charged electrode.

As soon as ions and other charged particles have time to move, the direction of the electric field changes, which forces them to reverse the direction of motion. With each period of high-frequency current, this process will be repeated. The charged particles will begin to oscillate with a very small amplitude around the middle position at the frequency of the high-frequency current. Such a current, at which the movement of charged particles occurs, in this case, oscillatory, is called the conduction current.

During their oscillatory movements, charged particles encounter resistance both when they collide with each other and with the surrounding tissue particles, which is accompanied by the formation of heat. The rotation of the dipole molecules also encounters resistance from the surrounding particles and is accompanied by the release of heat (the so-called dielectric losses). The turn in a high-frequency electric field of dipoles carrying charges at their ends is called the displacement current (polarization). Human body tissues have electrical capacitance and ohmic resistance, connected in parallel, which is schematically shown in Fig. 40. There is practically no inductive resistance in tissues.

Cell membranes are dielectrics, although imperfect, and interstitial fluids and protoplasm of cells have ionic conductivity. The result is microscopic capacitors (two conductors separated by a dielectric layer). The total capacity of the human body is quite significant and amounts to 0.01-0.02 microfarads.

At relatively low frequencies (for high-frequency currents up to several million hertz per second), ionic conductivity prevails, a conduction current arises, while at high frequencies (several tens of millions of hertz), the polarization current increases. At ultrahigh frequencies exceeding 1 billion Hz, the polarization current increases even more, the phenomena that are attributed to the oscillatory (oscillatory) action of high frequency currents become more pronounced; these include physicochemical shifts, in particular, an increase in the dispersion of proteins. The ionic composition and the number of polar molecules in different tissues differ from each other, therefore, at the same frequency, and hence the wavelength, an unequal amount of heat will arise in the tissues. In fact, all tissues will be heated, although the one for which the wavelength is closer to the selective (selective) one will be slightly larger. According to N.N. Malov, the wavelength of 2.1 m is selective for muscles, 2.6 m for blood, 6 m for skin, 5.5 m for liver, 11 m for brain, and 35 m for fat. It should be noted that the frequency and, accordingly, the wavelength of the oscillations generated by modern medical devices of high frequency are not sufficiently selective for the tissues of the human body. Despite this, the difference in tissue heating is manifested to one degree or another. Due to the very small shift of ions from the middle position during oscillatory movements, there is no pronounced change in the concentration of ions at the border of cell membranes, both outside and inside the cell; this can explain the absence of the irritating effect of high-frequency current on the tissue.

Pain sensitivity under the action of high-frequency currents decreases, which basically does not depend on the generated heat, but is the result of the oscillatory oscillatory effect of high-frequency currents. It is possible that in this case the connection between the elements of the nerve ending that perceives pain is disrupted, which leads to a decrease in its excitability; the higher the frequency of the current, the more pronounced its analgesic effect.

DEPARTMENT OF EDUCATION AND SCIENCE OF THE KEMEROV REGION

State educational institution of secondary vocational education

Kemerovo Vocational Technical School

High frequency currents.

Prepared by: physics teachers

Shcherbunova Evgeniya Olegovna and

Kolabina Galina Alekseevna

kemerovo

What are high frequency currents?

Currents with a frequency higher than 10,000 Hz are called high frequency currents (HFC). They are received using electronic devices.

If you place a conductor inside a coil through which a high frequency current flows, then eddy currents will arise in the conductor. Eddy currents heat up the conductor. The heating rate and temperature can be easily adjusted by changing the current in the coil.

The most refractory metals can be melted in an induction furnace. To obtain highly pure substances, melting can be carried out in a vacuum and even without a crucible, by suspending the molten metal in a magnetic field. The high heating rate is very convenient when rolling and forging metal. By choosing the shape of the coils, you can solder and weld parts at the best temperature conditions.

Induction Melting Furnace

The current i, flowing through the conductor, creates a magnetic field B. At very high frequencies, the influence of the vortex electric field E, generated by the change in the field B, becomes noticeable.

The influence of the E field increases the current on the surface of the conductor and weakens it in the middle. At a sufficiently high frequency, the current flows only in the surface layer of the conductor.

The method of surface hardening of steel products was invented and proposed by the Russian scientist V.P. Vologdin. At high frequency, the induction current heats only the surface layer of the workpiece. After rapid cooling, a non-fragile product with a hard surface is obtained.

Hardening machine

For more details see here: Induction heating and quenching installations

The action of high frequency currents on dielectrics

Dielectrics are acted upon by a high-frequency electric field, placing them between the capacitor plates. Part of the energy of the electric field is spent in this case for heating the dielectric. Heating with HFC is especially good if the thermal conductivity of the substance is low.

High-frequency heating of dielectrics (dielectric heating) is widely used for drying and gluing wood, for the production of rubber and plastics.

High frequency currents in medicine

UHF therapy is a dielectric heating of body tissues. Direct and low-frequency currents over several milliamperes are deadly for humans. The high frequency current (≈ 1 MHz), even at 1 A, causes only tissue heating and is used for treatment.

"Electroknife" is a high-frequency device widely used in medicine. It cuts tissue and seals the blood vessels.

Other applications of high frequency currents

Grain treated with HDTV before sowing significantly increases the yield.

Induction heating of gas plasma allows high temperatures to be obtained.

A 2400 MHz field in a microwave electric oven cooks the soup right on the plate for 2-3 minutes.

The action of the mine detector is based on the change in the parameters of the oscillatory circuit when the coil is brought to the metal object.

High-frequency currents are also used for radio communications, television and radar.

List of sources:

1. Dmitrieva, V.F. Physics: a textbook for student general educational institutions of secondary vocational education [Text] / V.F. Dmitrieva. –6th edition. stereotype. - M .: Publishing Center Academy, 2005. - 280-288.

Internet resources:

Single window of access to educational resources [Electronic resource]. - Access mode: http:// window. edu. ru/ window, free. - Title from the screen. - (Date of access: 11.11.2014).

Electronic library system "KnigaFond" [Electronic resource]. - Access mode: http://www.knigafund.ru/, for access to information. resources require authorization. - Title from the screen. - (Date of access: 11.11.2014).

Portal of natural sciences ”[Electronic resource]. - Access mode: http://e-science.ru/physics, free. - Title from the screen. - (Date of access: 11.11.2014).

MOTIVATION

The most promising direction of modern physiotherapy should be considered the further improvement of impulse rhythmic effects in the treatment of various pathological conditions, since impulse effects in a certain predetermined mode correspond to the physiological rhythms of functioning organs and their systems.

PURPOSE OF THE LESSON

Learn to use the following methods to treat diseases:

Electrosleep;

Transcranial electroanalgesia;

Short-pulse electroanalgesia;

Diadynamic therapy;

Electrodiagnostics;

Electrostimulation and electropuncture.

TARGETED ACTIVITIES

Understand the essence of the physiological action of impulse currents of low frequency. Be able to:

Determine indications and contraindications for the use of impulse currents of low frequency;

Choose an adequate type of therapeutic effect;

Independently appoint procedures;

Evaluate the effect of impulse currents on the patient's body.

To study the principles of operation of the devices "Electroson-5", "LENAR", "Tonus-3", "Mioritm".

INFORMATION BLOCK

Impulse methods of exposure to physical factors are the most adequate stimuli for the body, and in case of impaired functions, their therapeutic effect is most effective. The main advantages of impulse physiotherapy techniques:

Selectivity of action;

The possibility of a deeper impact;

Specificity;

Lack of quick adaptation of tissues to a physical factor;

Therapeutic effect with the least stress on the body.

Impulse currents consist of rhythmically repetitive short-term changes in electrical voltage or current. The possibility of using a pulsed current for a stimulating effect on various organs, tissues and systems of the body is based on the nature of electrical impulses that mimic the physiological effect of nerve impulses and cause a reaction similar to natural excitement. The action of an electric current is based on the movement of charged particles (ions of tissue electrolytes), as a result of which the usual composition of ions on both sides of the cell membrane changes and physiological processes that cause excitation develop in the cell.

Excitability can be judged by the least strength of the stimulus required for the occurrence of a reflex reaction, or by the threshold current strength, or by the threshold potential shift sufficient for the emergence of an action potential. Speaking of excitability, they use concepts such as rheobase and chronaxia. These concepts were introduced into physiology in 1909 by L. Lapik, who studied the smallest (threshold) effect of excitable tissues and determined the relationship between the current strength and the duration of its action. Rheobase (from the Greek "rheos" - flow, flow and "basis" - course, movement; base) is the smallest DC electric current that causes excitation in living tissues with a sufficient duration of action. Rheobase, like chronaxia, makes it possible to assess the excitability of tissues and organ-

new in terms of the threshold strength of irritation and the duration of its action. Rheobase corresponds to the threshold of irritation and is expressed in volts or milliamperes.

The reobase value can be calculated using the formula:

where I is the current strength, t is the duration of its action, and, b are constants determined by the properties of the tissue.

Chronaxia (from the Greek "chronos" - time and "axia" - price, measure) - the shortest time of action of a direct electric current of doubled threshold force (doubled rheobase), causing tissue excitation. As established experimentally, the magnitude of the stimulus causing excitation in the tissues is inversely proportional to the duration of its action, which is graphically expressed by hyperbole (Fig. 6).

The change in the functional state of cells, tissues and organs under the influence of an external electrical stimulus is called electrostimulation. Within the limits of electrostimulation, electrodiagnostics and electrotherapy are distinguished. In electrodiagnostics, the body's response to electrical stimulation by impulse currents is investigated. It was found that the irritating effect of a single current pulse depends on the steepness of the rise of its leading edge, the duration and amplitude of the pulse. The steepness of the rise of the front of a single pulse determines the acceleration of ions as they move. In addition, the effect of alternating electric current on the body depends significantly on its frequency. At a low pulse frequency (of the order of 50-100 Hz), the displacement of ions is sufficient to irritate the cell. At medium frequencies, the irritating effect of the current decreases. At a sufficiently high frequency (of the order of hundreds of kilohertz), the magnitude of the displacement of ions becomes commensurate with the magnitude of their displacement during thermal motion, which no longer causes a noticeable change in their concentration and does not have an irritating effect.

The value of the threshold amplitude determines the maximum instantaneous displacement of ions and depends on the duration of the pulses. This relationship is described by the Weiss-Lapik equation (see Fig. 6).

Each point of the curve in Fig. 6 and the points above the curve correspond to impulses that cause tissue irritation. Extremely short-term impulses do not have an irritating effect (the displacement of ions is commensurate with the amplitude

Fig. 6.Muscle electrical excitability curve (Weiss-Lapik).

vibrations during thermal motion). With rather long impulses, the irritating effect of the current becomes independent of the duration. Pulse parameters that provide an optimal response to irritation are used for therapeutic electrical stimulation. Modern development of electronics makes it possible to obtain pulse currents with any required parameters. In modern devices, pulses of various shapes are used, with a duration from tens of milliseconds to several seconds, with a repetition rate from fractions of a Hertz to ten thousand Hertz.

Electrosleep

Electrosleep is a method of neurotropic non-pharmacological action on the central nervous system with a constant impulse current of a rectangular configuration, low frequency (1-160 Hz) and low strength (10 mA). The method is notable for its harmlessness, absence of toxic effects, allergic reactions, addiction and cumulation.

It is believed that the mechanism of action of electrosleep is based on the direct effect of current on the structures of the brain. The impulse current, penetrating into the brain through the openings of the orbits, spreads through the vascular and cerebrospinal fluid spaces and reaches the sensitive nuclei of the cranial nerves, pituitary gland, hypothalamus, reticular formation and other structures. The reflex mechanism of action of electrosleep is associated with the effect of low-strength direct current pulses on the receptors of the reflexogenic zone: the skin of the eye sockets and the upper eyelid. In a reflex arc, irritation is transmitted to the subcortical formations, the cerebral cortex, causing the effect of protective inhibition. In the mechanism of the therapeutic effect of electric sleep, an essential role is played by the ability of the nerve cells of the brain to assimilate a certain rhythm of the impulse current.

Acting on the structures of the limbic system, electrosleep restores disturbances in the emotional, vegetative and humoral balance in the body. Thus, the mechanism of action consists of the direct and reflex influence of current impulses on the cerebral cortex and subcortical formations.

Impulse current is a weak stimulus that has a monotonous rhythmic effect on such structures of the brain as the hypothalamus and reticular formation. Synchronization of impulses with biorhythms of the central nervous system causes inhibition of the latter and leads to the onset of sleep. Electrosleep has an analgesic, hypotensive effect, has a sedative and trophic effect.

The electrosleep procedure has two phases. The first is inhibitory, associated with stimulation of subcortical formations by impulse current and manifested by drowsiness, drowsiness, sleep, decreased pulse rate, respiration, decreased blood pressure and bioelectrical activity of the brain. This is followed by the disinhibition phase, associated with an increase in the functional activity of the brain, self-regulation systems and manifested by increased efficiency and improved mood.

Electrosleep has a calming effect on the body, induces sleep that is close to physiological. Under the influence of electrosleep, conditioned reflex activity decreases, respiration and pulse decrease, small arteries expand, blood pressure decreases; the analgesic effect is manifested. In patients with neuroses, emotional stress and neurotic reactions weaken. Electrosleep is widely used in psychiatric practice; at the same time, the disappearance of anxiety and sedation are noted. Indications for the appointment of electrosleep in patients with chronic ischemic heart disease (IHD) and postinfarction cardiosclerosis:

Cardialgia;

Feeling of fear of death;

Insufficient effectiveness of sedatives and hypnotics.

Electrosleep effects:

In the first phase:

❖ anti-stress;

❖ sedative;

❖ tranquilizing;

In the second phase:

❖ stimulating;

❖ relieves mental and physical fatigue.

For carrying out procedures of electrosleep, generators of voltage pulses of constant polarity and rectangular configuration with a certain duration and adjustable frequency are used: "Electroson-4T" and "Electroson-5".

The procedures are carried out in a quiet, darkened room with a comfortable temperature. The patient lies on the couch in a comfortable position. The technique is retromastoidal. Eye electrodes with wetted hydrophilic pads 1 cm thick are placed on closed eyelids and connected to the cathode; the occipital electrodes are fixed on the mastoid processes of the temporal bones and attached to the anode. The strength of the current is dosed according to a slight tingling sensation or painless vibration felt by the patient. If unpleasant sensations appear in the area of \u200b\u200bapplication of the electrodes, the strength of the supplied current should be reduced, usually not exceeding 8-10 mA. The pulse frequency is selected depending on the functional state of the patient. In diseases caused by the development of organic, degenerative processes in the vessels and nervous tissue of the brain, the effect occurs if an impulse frequency of 5-20 Hz is used, and in case of functional disorders of the central nervous system - 60-100 Hz. Simultaneously with electrophoresis, you can carry out electrophoresis of medicinal substances. Procedures lasting from 30-40 to 60-90 minutes, depending on the nature of the pathological process, are carried out daily or every other day; the course of treatment includes 10-20 exposures.

Indications for treatment:

Neuroses;

Hypertonic disease;

Ischemic heart disease (coronary insufficiency of the 1st degree);

Obliterating vascular diseases of the extremities;

Atherosclerosis of cerebral vessels in the initial period;

Bronchial asthma;

Rheumatoid arthritis in the presence of neurasthenia or psychasthenia;

Pain syndrome;

Phantom pain;

Post-traumatic encephalopathy (in the absence of arachnoiditis);

Schizophrenia during asthenization after active drug treatment;

Diencephalic syndrome;

Neurodermatitis;

Toxicosis of pregnancy;

Preparing pregnant women for childbirth;

Violation of menstrual function;

Premenstrual and climacteric syndrome;

Meteotropic reactions;

Logoneurosis;

Stressful states and prolonged emotional stress. Contraindications:

Current intolerance;

Inflammatory and dystrophic eye diseases;

Retinal disinsertion;

High degree of myopia;

Dermatitis of the facial skin;

Hysteria;

Post-traumatic arachnoiditis;

The presence of metal objects in the tissues of the brain and eyeball.

Transcranial electroanalgesia

Transcranial electroanalgesia is a method of neurotropic therapy based on the impact on the central nervous system of pulsed currents of a rectangular configuration with a frequency of 60-2000 Hz with variable and constant duty cycle.

The therapeutic action is based on selective excitation of the endogenous opioid system of the brain stem by low-frequency impulse currents. Pulse currents change the bioelectric activity of the brain, which leads to a change in the activity of the vasomotor center and is manifested by the normalization of systemic hemodynamics. In addition, the release of endogenous opioid peptides into the bloodstream activates regenerative-reparative processes in the inflammation focus.

Transcranial electroanalgesia is a method with pronounced sedative (at a frequency of up to 200-300 Hz), tranquilizing (at 800-900 Hz) and analgesic (above 1000 Hz) effects.

Apparatus and general instructions for performing procedures

For transcranial electroanalgesia procedures, devices are used that generate rectangular pulses with voltage up to 10 V with a frequency of 60-100 Hz, duration 3.5-4 ms: "TRANSAIR", "Etrans-1, -2, -3" - and voltage up to 20 V with a frequency of 150-2000 Hz ("LENAR", "Bi-LENAR"). The strength of the analgesic effect increases with the inclusion of an additional constant component of the electric current. The optimal ratio of direct and impulse current is 5: 1-2: 1.

During the procedure, the patient lies on the couch in a comfortable position. The fronto-mastoid technique is used: a bifurcated cathode with gaskets moistened with warm water or 2% sodium bicarbonate solution is installed in the region of the brow arches, and a bifurcated anode is placed under the mastoid processes. After choosing the parameters of transcranial electroanalgesia (frequency, duration, duty cycle and amplitude of the constant component), the amplitude of the output voltage is gradually increased until the patient develops a tingling sensation and light heat under the electrodes. The duration of exposure is 20-40 minutes. The course of treatment includes 10-12 procedures.

For transcerebral electroanalgesia, sinusoidally modulated currents are also used with the following parameters:

The duration of half periods is 1: 1.5;

Variable mode;

Modulation depth 75%;

Frequency 30 Hz.

The duration of the procedure is 15 minutes. The procedures are carried out daily, the course of treatment includes 10-12 manipulations. During the procedure, an electronic rubber half mask from the electric sleep apparatus is used, replacing the plug with a plug device for the Amplipulse series apparatus.

Indications for treatment:

Neuralgia of the cranial nerves;

Pain due to vertebral pathology;

Phantom pain;

Vegetodystonia;

Exertional angina pectoris I and II functional class;

Peptic ulcer and duodenal ulcer;

Neurasthenia;

Neurodermatitis;

Overwork;

Alcohol withdrawal syndrome;

Sleep disturbance;

Meteopathic reactions. Contraindications:

General contraindications to physiotherapy;

Current intolerance;

Acute pain of visceral origin (angina attack, myocardial infarction, renal colic, childbirth);

Closed brain injury;

Diencephalic syndrome;

Thalamic syndrome;

Violation of the rhythm of the heart;

Damage to the skin at the places of application of the electrodes.

Healing techniques

With hypertension stage I and II and ischemic heart diseasefor electric sleep, the orbital-retromastoidal technique is used using a rectangular pulse current with a frequency of 5-20 Hz, lasting from 30 minutes to 1 hour, daily. The course of treatment consists of 12-15 procedures.

Transcranial electrotranquilization is performed according to the lobnoretromastoidal technique using a rectangular pulse current with a frequency of 1000 Hz, lasting 30-45 minutes daily. The course of treatment consists of 12-15 procedures.

With stable hypertensionapply electrosleep using a rectangular pulse current with a frequency of 100 Hz (the first 5-6 procedures); then they switch to 10 Hz. The duration of the procedures is 30-45 minutes. The course of treatment includes 10-12 daily procedures.

With diencephalic syndrome and neurosesapply electrosleep using a rectangular pulse current with a frequency of 10 Hz for a duration from 30 minutes to 1 hour, every other day. The course of treatment consists of 10-12 procedures.

Transcranial electrotranquilization is carried out according to the frontorethromastoidal technique using a rectangular pulse current with a frequency of 1000 Hz, lasting 30-40 minutes. The course of treatment includes 12-15 daily procedures.

With traumatic encephalopathyelectrosleep is applied according to the ocular-retromastoidal technique using a rectangular pulse current with a frequency of 10 Hz for a duration from 30 minutes to 1 hour, every other day. The course of treatment includes 10-12 procedures.

Short-pulse electroanalgesia

Short-pulse electroanalgesia (percutaneous electroneurostimulation) is an effect on a painful focus with very short (20-500 μs) current pulses, followed by bursts of 20-100 pulses with a frequency of 2 to 400 Hz.

The duration and repetition rate of current pulses used in short-pulse electroanalgesia are very similar to the corresponding parameters of pulses of thick myelinated Ap fibers. In this regard, the flow of rhythmic ordered afferentation created during the procedure excites the neurons of the gelatinous substance of the posterior horns of the spinal cord and blocks the conduction of nocigenic information at their level. Excitation of the interneurons of the posterior horns of the spinal cord leads to the release of opioid peptides in them. The analgesic effect is enhanced by an electric impulse effect on the paravertebral zones and areas of reflected pain.

Fibrillation of smooth muscles of arterioles and superficial muscles of the skin, caused by electrical impulses, activates the processes of utilization of algogenic substances (bradykinin) and mediators (acetylcholine, histamine) released during the development of pain syndrome. Strengthening local blood flow activates local metabolic processes and local protective properties of tissues. Along with this, perineural edema decreases and depressed tactile sensitivity in areas of local pain is restored.

Apparatus and general instructions for performing procedures

For the procedures, the devices "Delta-101 (-102, -103)", "Eliman-401", "Bion", "Neuron", "Impulse-4", etc. are used. During the procedures, electrodes are applied and fixed

in the area of \u200b\u200bthe projection of the painful focus. By the principle of their placement, peripheral electroanalgesia is distinguished, when the electrodes are placed in areas of pain, points of exit of the corresponding nerves or their projection, as well as in reflexogenic zones, and segmental electroanalgesia, in which the electrodes are placed in the region of paravertebral points at the level of the corresponding spinal segment. Most often, two types of short-pulse electroanalgesia are used. In the first case, current pulses with a frequency of 40-400 Hz with a force of up to 5-10 mA are used, causing rapid (2-5 minutes) analgesia of the corresponding metamer, which lasts at least 1-1.5 hours. When exposed to biologically active points (BAP) use current pulses up to 15-30 mA, supplied with a frequency of 2-12 Hz. Hypoalgesia develops in 15-20 minutes and captures, in addition to the area of \u200b\u200bimpact, and neighboring metameres.

The parameters of the impulse currents are dosed in terms of amplitude, repetition rate and duty cycle, taking into account the stage of development of the pain syndrome. Along with this, the appearance of a feeling of hypoalgesia in the patient is taken into account. During the procedure, the patient should not have pronounced muscle fibrillation in the area where the electrodes are located. Exposure time - 20-30 minutes; procedures are carried out up to 3-4 times a day. The duration of the course depends on the effectiveness of pain relief.

Indications for treatment are pain syndromes in patients with diseases of the nervous system (sciatica, neuritis, neuralgia, phantom pain) and musculoskeletal system (epicondylitis, arthritis, bursitis, sprains, sports injury, bone fractures).

Contraindications:

Current intolerance;

General contraindications to physiotherapy;

Acute pains of visceral origin (angina pectoris attack, myocardial infarction, renal colic, labor pains);

Diseases of the membranes of the brain (encephalitis and arachnoiditis);

Neuroses;

Psychogenic and ischemic pain;

Acute purulent inflammatory process;

Thrombophlebitis;

Acute dermatoses;

The presence of metal fragments in the affected area.

Diadynamic therapy

Diadynamic therapy (DDT) is an electrotherapy method based on exposure to a low-frequency pulsed current of a constant direction of a half-sinusoidal shape with an exponential trailing edge of 50 and 100 Hz in various combinations.

DDT has an analgesic effect. The analgesic effect of DDT is due to processes developing at the level of the spinal cord and brain. Irritation by a rhythmic impulse current of a large number of nerve endings leads to the appearance of a rhythmically ordered flow of afferent impulses. This flow blocks the passage of pain impulses at the level of the gelatinous substance of the spinal cord. The analgesic effect of DDT is also facilitated by reflex excitation of the endorphin systems of the spinal cord, resorption of edema and reduction of compression of the nerve trunks, normalization of trophic processes and blood circulation, elimination of hypoxia in tissues.

The direct effect of DDT on body tissues differs little from the effect of galvanic current. The reaction of individual organs, their systems and the body as a whole is due to the impulsive nature of the supplied current, which changes the ratio of ion concentrations at the surface of cell membranes, inside cells and in intercellular spaces. As a result of changing ionic composition and electrical polarization, the dispersion of colloidal solutions of the cell and the permeability of cell membranes change, the intensity of metabolic processes and the excitability of tissues increase. These changes are more pronounced at the cathode. Local changes in tissues, as well as the direct action of the current on receptors, cause the development of segmental reactions. In the foreground is hyperemia under the electrodes due to vasodilation and increased blood flow. In addition, when exposed to DDT, reactions caused by current pulses develop.

Due to the changing concentration of ions at the surface of cell membranes, the dispersion of cytoplasmic proteins and the functional state of the cell and tissue change. With rapid changes in the concentration of ions, the muscle fiber contracts (with a low current strength, it strains). This is accompanied by an increase in blood flow to the excited fibers (and to any other working organ) and an intensification of metabolic processes.

Blood circulation also increases in areas of the body innervated from the same segment of the spinal cord, including the symmetrical region. At the same time, the blood flow to the affected area, as well as the venous outflow, increases, the resorption capacity of the mucous membranes of the cavities (pleural, synovial, peritoneal) improves.

Under the influence of DDT, the tone of the great vessels is normalized and collateral circulation is improved. DDT affects the functions of the stomach (secretory, excretory and motor), improves the secretory function of the pancreas, stimulates the production of glucocorticoids by the adrenal cortex.

Diadynamic currents are obtained by single- and full-wave rectification of alternating mains current with a frequency of 50 Hz. In order to reduce adaptation to influences and increase the effectiveness of treatment, several types of current have been proposed, representing a sequential alternation of currents with a frequency of 50 and 100 Hz or an alternation of the latter with pauses.

Half-wave continuous (OH) half-sinusoidal current with a frequency of 50 Hz has a pronounced irritating and myostimulating properties, up to tetanic muscle contraction; causes a large, unpleasant vibration.

Full-wave continuous (DN) half-sinusoidal current with a frequency of 100 Hz has a pronounced analgesic and vasoactive properties, causes fibrillar muscle twitching, small diffuse vibration.

One-half rhythmic (RR) current, the transmissions of which alternate with pauses of equal duration (1.5 s), has the most pronounced myostimulating effect during the transmission of current, combined with a period of complete muscle relaxation during the pause.

A short-period modulated current (CP) is a sequential combination of OH and DN currents following equal bursts (1.5 s). The alternation significantly reduces the adaptation to the impact. This current first has a neuromyostimulating effect, and after 1-2 minutes - an analgesic effect; makes the patient feel the alternation of a large and soft gentle vibration.

Long-period modulated current (LP) is a simultaneous combination of OH current pulses with a duration of 4 s and

current DN with a duration of 8 s. The neuromyostimulating effect of such currents decreases, but the analgesic, vasodilating and trophic effects gradually increase. The patient's sensations are similar to those in the previous exposure regime.

One-half-wave wave (OF) current is a series of half-wave current pulses with an amplitude that increases from zero to a maximum value for 2 s, remains at this level for 4 s, and then decreases to zero for 2 s. The total duration of the pulse is 8 s, the duration of the entire period is 12 s.

Full-wave wave (DW) current is a series of full-wave current pulses with an amplitude that changes in the same way as that of the OF current. The total duration of the period is also 12 s.

The diadynamic current has an injecting ability, which determines its use in the methods of drug electrophoresis (diadynamophoresis). Yielding to the galvanic current in terms of the amount of the administered drug, it contributes to its deeper penetration, often potentiating its action. It is best to prescribe diadynamophoresis when pain prevails.

Apparatus and general instructions for performing procedures

For DDT procedures, devices are used that generate pulses of different duration, frequency and shape with different duration of pauses between messages, such as "Tonus-1 (-2, -3)", "SNIM-1", "Diadynamic DD-5A" and etc.

When carrying out the DDT procedure, hydrophilic gaskets of electrodes of the required size are moistened with warm tap water, squeezed, metal plates are placed in the pockets of the gaskets or on top of them. Cup electrodes are placed in the area of \u200b\u200bthe most pronounced pain sensations and during the procedure are held by the hand on the handle of the electric holder. An electrode is placed on the painful point, connected to the negative pole of the apparatus - the cathode; another electrode of the same area is placed next to the first at a distance equal to its diameter or more. With electrodes of different areas, the smaller electrode (active) is placed on the painful point, the larger (indifferent) is placed on a significant

distance (in the proximal part of the nerve trunk or limb). With DDT, water can be used as an active electrode on the area of \u200b\u200bsmall joints of the hand or foot: it is filled into a glass or ebonite bath and the bath is connected to the negative pole of the apparatus through a carbon electrode.

Depending on the severity of the pathological process, the stage of the disease, the reactivity of the patient (the property of the tissue to respond differentially to the action of an external stimulus; in this case, the action of a physiotherapeutic factor or changes in the internal environment of the body), individual characteristics of the body and the therapeutic tasks to be solved, one or another type of DDT is used, as well as their combination. To reduce addiction and gradually increase the intensity of exposure, 2-3 types of DDT current are used on the same part of the body.

The strength of the current is selected individually, taking into account the subjective sensations of the patient (slight tingling, burning, feeling of electrode slipping, vibration, intermittent compression or contraction of muscles in the area of \u200b\u200bexposure). With DDT of pain syndrome, the current strength is selected so that the patient feels a pronounced painless vibration (from 2-5 to 15-30 mA). During the procedure, addiction to the action of DDT is noted; this must be taken into account and, if necessary, the intensity of the impact must be increased. The duration of the procedure is 4-6 minutes in one area, the total exposure time is 15-20 minutes. The course of treatment includes 5-10 daily procedures.

Indications for treatment:

Neurological manifestations of osteochondrosis of the spine with pain syndromes (lumbago, radiculitis, radicular syndrome), motor and vascular-trophic disorders;

Neuralgia, migraine;

Diseases and injuries of the musculoskeletal system, myositis, arthrosis, periarthritis;

Diseases of the digestive system (peptic ulcer and duodenal ulcer, pancreatitis);

Chronic inflammatory diseases of the uterine appendages;

Hypertension in the initial stages. Contraindications:

Current intolerance;

General contraindications to physiotherapy;

Acute inflammatory processes (purulent);

Thrombophlebitis;

Non-fixed fractures;

Hemorrhage in the cavity and tissue;

Tears of muscles and ligaments.

Healing techniques

Diadynamic therapy in the treatment of trigeminal neuralgia

Small round electrodes are used. One electrode (cathode) is placed at the exit site of one of the branches of the trigeminal nerve, the second - in the area of \u200b\u200bpain irradiation. Impact with current DN 20-30 s, and then with current KP for 1-2 minutes. The current strength is gradually increased until the patient feels a pronounced painless vibration; the course of treatment includes up to six daily procedures.

Diadynamic therapy in the treatment of migraine

The position of the patient is lying on the side. They act with round electrodes on a hand holder. The cathode is installed 2 cm behind the corner of the lower jaw on the area of \u200b\u200bthe upper cervical sympathetic node, the anode is 2 cm higher. The electrodes are placed perpendicular to the surface of the neck. Apply the DN current for 3 min; the current strength is gradually increased until the patient feels a pronounced vibration. The impact is carried out from two sides. The course consists of 4-6 daily procedures.

Diadynamic therapy for headaches associated with a hypotensive state, cerebral atherosclerosis (according to V.V. Sinitsin)

The position of the patient is lying on the side. Small double electrodes are used on a hand-held holder. The electrodes are placed in the temporal region (at the level of the eyebrow) so that the temporal artery is in the interelectrode space. The KP current is applied for 1-3 minutes, followed by a change in polarity for 1-2 minutes. During one procedure, the right and left temporal arteries are acted upon alternately. The procedures are carried out daily or every other day, the course of treatment consists of 10-12 procedures.

Diadynamic therapy for the gallbladder area

The plate electrodes are positioned as follows: an active electrode (cathode) with an area of \u200b\u200b40-50 cm 2 is placed on the projection area of \u200b\u200bthe gallbladder in front, the second electrode (anode) with a size of 100-120 cm 2 is placed transversely on the back.

OV is used in a constant or variable mode of operation (in the latter, the duration of the period is 10-12 s, the rise time of the leading edge and the fall of the trailing edge is 2-3 s each). The current strength is increased until pronounced contractions of the muscles of the anterior abdominal wall begin under the electrodes. The duration of the procedure is 10-15 minutes daily or every other day, the course of treatment consists of 10-12 procedures.

Diadynamic therapy for the muscles of the anterior abdominal wallElectrodes with an area of \u200b\u200b200-300 cm 2 are placed on the abdominal wall (cathode) and in the lumbosacral region (anode). DDT parameters: OV-current in constant operation mode; the current strength is increased until the appearance of pronounced contractions of the abdominal wall, the exposure time is 10-12 minutes. The course of treatment includes up to 15 procedures.

Diadynamic therapy for the perineal region

Electrodes with an area of \u200b\u200b40-70 cm 2 are positioned as follows:

Above the pubic joint (anode) and on the perineum (cathode);

Above the pubic articulation and on the perineal area under the scrotum (polarity depends on the purpose of exposure);

Above the symphysis pubis (cathode) and on the lumbosacral spine (anode).

DDT parameters: half-wave current in alternating mode of operation, period duration 4-6 s. Syncope rhythm can be used with alternating operation. With good tolerance, the current strength is increased until the patient feels a pronounced vibration. The duration of the procedure is up to 10 minutes daily or every other day, the course of treatment includes up to 12-15 procedures.

The effect of diadynamic therapy on the genitals of a woman

Electrodes with an area of \u200b\u200b120-150 cm 2 are placed transversely above the pubic articulation and in the sacral region. DDT parameters: DN with polarity reversal - 1 min; CP - 2-3 minutes, DP - 2-3 minutes. The procedures are carried out daily or every other day. The course of treatment consists of 8-10 procedures.

Diadynamic therapy for diseases of the shoulder joint

Plate electrodes are placed transversely on the anterior and posterior surfaces of the joint (the cathode is at the site of the projection of pain).

DDT parameters: DV (or DN) - 2-3 min, CP - 2-3 min, DP -

3 min. For pain under both electrodes in the middle of exposure

with each type of current, the polarity is reversed. The strength of the current is increased until the patient feels a pronounced painless vibration. The course is prescribed 8-10 procedures, carried out daily or every other day.

Diadynamic therapy for bruised or sprained joint ligaments

Round electrodes are placed on both sides of the joint at the most painful points. Impact with the current of the DN for 1 min, and then - KP for 2 min in the forward and backward directions. The strength of the current is increased until the patient feels the most pronounced vibration. The procedures are carried out daily. The course of treatment consists of 5-7 procedures.

Electrostimulation

Electrical stimulation is a method of treatment with impulse currents of low and increased frequency, used to restore the activity of organs and tissues that have lost their normal function, as well as to change the functional state of muscles and nerves. Separate impulses are applied; series, consisting of several impulses, as well as rhythmic impulses alternating with a certain frequency. The nature of the reaction caused depends on:

Intensity, configuration and duration of electrical impulses;

The functional state of the neuromuscular apparatus. These factors, closely related to each other, lie in

based on electrodiagnostics, allowing you to select the optimal parameters of the impulse current for electrical stimulation.

Electrical stimulation supports muscle contractility, enhances blood circulation and metabolic processes in tissues, and prevents the development of atrophy and contractures. The procedures, carried out in the correct rhythm and with the appropriate current strength, create a stream of nerve impulses that enter the central nervous system, which in turn contributes to the restoration of motor functions.

Indications

Electrostimulation is most widely used in the treatment of diseases of the nerves and muscles. These diseases include various paresis and paralysis of skeletal muscles, such as flaccidity, caused by disorders of the peripheral nervous system.

we and the spinal cord (neuritis, the consequences of poliomyelitis and spinal injuries with damage to the spinal cord), and spastic, post-stroke. Electrical stimulation is indicated for aphonia due to paresis of the muscles of the larynx, paretic state of the respiratory muscles and diaphragm. It is also used for muscle atrophy, both primary, which developed as a result of injuries of peripheral nerves and spinal cord, and secondary, which arose as a result of prolonged immobilization of the limbs in connection with fractures and osteoplastic operations. Electrical stimulation is indicated for atonic states of smooth muscles of internal organs (stomach, intestines, bladder). The method is used for atonic bleeding, for the prevention of postoperative phlebothrombosis, for the prevention of complications during prolonged physical inactivity, for improving the fitness of athletes.

Electrical stimulation is widely used in cardiology. A single high-voltage electrical discharge (up to 6 kV), the so-called defibrillation, is able to restore the functioning of a stopped heart and bring a patient with myocardial infarction out of a state of clinical death. An implantable miniature device (pacemaker), which delivers rhythmic impulses to the patient's heart muscle, ensures long-term effective heart function when its pathways are blocked.

Contraindications

Contraindications include:

Gallstone and kidney stone disease;

Acute purulent processes in the abdominal organs;

Muscle spasticity.

Electrical stimulation of facial muscles is contraindicated with an increase in their excitability, as well as with early signs of contracture. Electrical stimulation of the muscles of the extremities is contraindicated in case of ankylosis of the joints, dislocations before their reduction, fractures of bones before their consolidation.

General instructions for performing procedures

Electrostimulation procedures are dosed individually according to the strength of the irritating current. During the procedure, the patient should experience intense, visible, but painless muscle contractions. The patient should not experience any discomfort. Absence of muscle contractions or painful sensations indicate improper placement of the electrodes or inadequacy of the applied current. The duration of the procedure

ry is individual and depends on the severity of the pathological process, the number of affected muscles and the method of treatment.

In physiotherapy, electrical stimulation is used mainly to act on damaged nerves and muscles, as well as on the smooth muscles of the walls of internal organs.

Electrodiagnostics

Electrodiagnostics is a method that allows you to determine the functional state of the peripheral neuromuscular apparatus using some forms of current.

When a nerve or muscle is irritated by a current, their bioelectric activity changes and spike responses are formed. By changing the rhythm of stimulation, one can detect a gradual transition from single contractions to serrated tetanus (when the muscle has time to partially relax and contract again under the action of the next current impulse), and then to full tetanus (when the muscle does not relax at all due to the frequent repetition of current impulses). These reactions of the neuromuscular apparatus when irritated by constant and impulse currents formed the basis of classical electrodiagnostics and electrical stimulation.

The main task of electrodiagnostics is to determine the quantitative and qualitative changes in the reaction of muscles and nerves to irritation by tetanizing and intermittent direct current. Repeated electrodiagnostic studies allow to establish the dynamics of the pathological process (restoration or deepening of the lesion), assess the effectiveness of treatment and obtain the necessary information for prognosis. In addition, the correct assessment of the state of electrical excitability of the neuromuscular apparatus allows you to select the optimal parameters of the current for electrical stimulation.

Electrical stimulation maintains contractility and muscle tone, improves blood circulation and metabolism in the affected muscles, slows down their atrophy, and restores high lability of the neuromuscular apparatus. During electrical stimulation, on the basis of electrodiagnostic data, the shape of the pulse current, the pulse repetition rate are selected and their amplitude is adjusted. At the same time, they achieve pronounced painless rhythmic muscle contractions. The duration of the pulses used is 1-1000 ms. The strength of the current for the muscles of the hand and face composition -

it is 3-5 mA, and for the muscles of the shoulder, lower leg and thigh - 10-15 mA. The main criterion for adequacy is obtaining an isolated painless muscle contraction of the maximum size when exposed to a current of minimal force.

Apparatus and general instructions for performing procedures

For carrying out electrodiagnostics, the "Neuropulse" apparatus is used. When electrodiagnostics are used:

Intermittent direct current with a rectangular pulse duration of 0.1-0.2 s (with manual interruption);

Tetanizing current with pulses of triangular configuration, frequency 100 Hz and pulse duration 1-2 ms;

Pulse current of rectangular shape and pulse current of exponential shape with pulse frequency adjustable in the range of 0.5-1200 Hz and pulse duration adjustable in the range of 0.02-300 ms.

The study of electrical excitability is carried out in a warm, well-lit room. The muscles of the study area and the healthy (symmetrical) side should be as relaxed as possible. When carrying out electrodiagnostics, one of the electrodes (guide, with an area of \u200b\u200b100-150 cm 2) with a wetted hydrophilic pad is placed on the sternum or spine and connected to the anode of the apparatus. The second electrode, previously covered with a hydrophilic cloth, is periodically moistened with water. In the process of electrodiagnostics, the reference electrode is placed on the motor point of the nerve or muscle under investigation. These points correspond to the projection of the nerves in the place of their most superficial location or the places of entry of the motor nerve into the muscles. On the basis of special research R. Erb at the end of the XIX century. compiled tables showing the typical location of the motor points, where the muscles contract at the lowest amperage.

For myoneurostimulation, the devices "Miorhythm", "Stimul-1" are used. For insignificantly expressed lesions of nerves and muscles, devices for DDT and amplipulse therapy (in a straightened mode) are also used for electrical stimulation. Internal organs are stimulated using the Endoton-1 apparatus.

The Stimul-1 device generates three types of impulse currents. For electrical stimulation with this device, plate electrodes with hydrophilic pads of various areas are used,

as well as strip electrodes of a special design. In addition, electrodes on a handle with a push-button breaker are used. The location of the points is noted by the doctor during the electrodiagnostics.

For electrical stimulation of nerves and muscles with pronounced pathological changes, a bipolar technique is used, in which two equal-sized electrodes with an area of \u200b\u200b6 cm distal section. In the bipolar technique, both electrodes are placed along the stimulated muscle and fixed with a bandage so that muscle contraction is unobstructed and visible. During electrical stimulation, the patient should not experience unpleasant pain sensations; after muscle contraction, its rest is necessary. The greater the degree of muscle damage, the less frequently the contractions are caused (from 1 to 12 contractions per minute), the longer the rest after each contraction. As muscle movement is restored, the frequency of contractions gradually increases. With active stimulation, when the current is turned on simultaneously with the patient's attempt to make a volitional muscle contraction, the number and duration of impulses are regulated by a manual modulator.

The strength of the current is regulated during the procedure, achieving pronounced painless muscle contractions. The current strength varies depending on the muscle group - from 3-5 mA to 10-15 mA. The duration of the procedure and the course of electrical muscle stimulation depends on the nature of the muscle damage and its severity. The procedures are carried out 1-2 times a day or every other day. The course of treatment is 10-15 procedures.

Indications for electrical stimulation:

Flaccid paresis and paralysis associated with nerve trauma, specific or nonspecific inflammation of the nerve, toxic nerve damage, degenerative-dystrophic diseases of the spine;

Central paresis and paralysis associated with impaired cerebral circulation;

Muscle atrophy with prolonged physical inactivity, immobilization dressings;

Hysterical paresis and paralysis;

Postoperative intestinal paresis, various dyskinesias of the stomach, intestines, biliary and urinary tract, ureteral stones;

Muscle stimulation to improve peripheral arterial and venous circulation and lymph drainage;

Increase and strengthen the muscle mass of athletes. Contraindications:

Current intolerance;

General contraindications to physiotherapy;

Acute inflammatory processes;

Contracture of facial muscles;

Bleeding (other than dysfunctional uterine);

Bone fractures before immobilization;

Dislocation of joints before reduction;

Ankylosis of the joints;

Fractures of bones before their consolidation;

Cholelithiasis;

Thrombophlebitis;

Condition after acute cerebrovascular accident (first 5-15 days);

Suture of a nerve, a vessel during the first month after surgery;

Spastic paresis and paralysis;

Heart rhythm disorders (atrial fibrillation, polytopic extrasystole).