High frequency therapy

, medical expert
Last reviewed: 23.04.2024

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The main active factor in all methods of high-frequency therapy is considered to be an alternating current that either directly enters the patient's body (darsonvalization, ultratonotherapy) or occurs in the tissues and media of the organism under the influence of alternating high-frequency electromagnetic fields or their constituents (i.e. Electric and magnetic fields) high, ultra-high and ultra-high frequency.

Electromagnetic waves with a wavelength of 0.05 mm to 10,000 m (frequency less than 6 × 1012 Hz) are called radio waves (radio waves are known to be used for wireless data transmission over long distances). Thus, high-frequency therapy can be called radio wave therapy. Classification of methods using high-frequency currents and electromagnetic fields, based on spectral characteristics.

The physiological and therapeutic effect of high-frequency oscillations is based on their interaction with charged particles of biological tissues, including not only ions, but proteins, low-molecular metabolites, polar heads of phospholipids, nucleic acids. Since the aforementioned charged molecules have different sizes, their motion will occur at different resonant frequencies.

Under the action of high-frequency fields, oscillations and collisions of free carriers occur, which in living tissues are ions. This effect is the basis of the conduction current. A molecule can be neutral, but at the same time there will be charges on its ends (simply in the sum they will give zero). Such a molecule, called a dipole, will rotate in an alternating field, which also results in the release of heat. The amount of generated heat depends both on the parameters of the acting factor (current intensity, its frequency), and electrical properties of the tissues themselves. Therefore, high-frequency therapy is selective.

In practice, this means that by changing the frequency, it is possible to achieve selective heating of certain tissues. Since the heating of tissues is caused by the absorption of certain resonance frequencies, it is carried out from the inside, and the sensitive sensors on the skin do not feel heat. The increase in the temperature of the tissues is accompanied by hyperemia, increased permeability of histohematological barriers and microcirculation, as well as by stimulation of metabolic processes.

Ultrasound therapy is widely and successfully used in dermatology and cosmetology for the treatment of: diathesis, eczema, neurodermatitis, acne, furuncles, for the removal of warts, post-operative scars and skin lesions. Increasing the effectiveness of treatment is facilitated by the preliminary application of medicinal or cosmetic products.

Darsonvalization is a method of electrotherapy based on the use of variable high-frequency pulse current (50-110 kHz), high voltage (up to 25 kV) and low power (up to 0.02 mA), modulated with short pulses (50-100 μs) the modulation frequency is 50 Hz. The method was proposed in 1892 by the French physiologist and physicist J.-A. D'Arsonval, in whose honor he was named. The active factor is the electrical discharge that occurs between the electrodes and the patient's body.

The intensity of the discharge can be changed from "quiet" to spark. During darsonvalization under the influence of discharges, ozone and nitrogen oxides are formed in small amounts, with which a bacteriostatic and bactericidal effect is associated. Unlike ultrathonotherapy, with darsonvalization due to low current strength and impulsive nature of the action, in which pauses significantly exceed the pulse time, the thermal effect is almost absent.

Darsonvalization is used mainly for local procedures.

Under the influence of D'Arsonval currents, the sensitivity thresholds of the skin receptors (pain, tactile, temperature, etc.) rise to external stimuli. Numerous signals come from the receptors of the zone of influence to the central nervous system and its vegetative centers, as a result, a reduction or cessation of pain, itching, paresthesia is observed.

Local darsonvalization, in addition, increases the turgor and elasticity of the skin, stimulates the proliferative activity of embryonic cells of the hair bulb, enhances hair growth, prevents the development of wrinkles and hair loss. The beneficial effect of darsonvalization on the condition of the skin explains its wide popularity in dermatology and cosmetology.

Inductothermy (syn: shortwave diathermy, shortwave therapy) is a method of electrotherapy, which involves exposure to certain areas of the patient's body with a high-frequency (usually 13, 56 MHz) alternating magnetic field. In this method, a high frequency current flows through the patient's cable or spiral (inductor), resulting in an alternating magnetic field. This field induces in conductors, which are mainly liquid media (blood, lymph), as well as well-blood-supplying tissues (muscles), chaotic eddy currents (Foucault currents).

Eddy currents warm the tissues from the inside, increasing their temperature by 2-5 ° C at a depth of 8-12 cm. The main factor that has a therapeutic effect with inductothermia is heat, and the effect of this heat is much stronger than the heat supplied from the outside. Inductothermy, heat is formed in the depths of tissues, mainly in muscles, thereby greatly reducing the effectiveness of thermoregulatory mechanisms, most of whose receptors are located in the surface tissues.

As a result of the increase in the temperature of the tissues, the blood vessels expand, the lympho- and blood circulation increases, the number of functioning capillaries increases, a slight decrease in arterial pressure is observed, the blood supply of the internal organs in the affected area improves, and the formation of arterial collaterals and anastomoses in the microcirculatory bed accelerates. Inductothermy has a positive effect on immunity: the synthesis of antibodies is stimulated, the content of humoral immunity in the blood increases, the phagocytic activity of leukocytes and macrophages increases, and fibroblasts become more active.

Inductothermia can be combined with drug electrophoresis (this method is called inductothermoelectrophoresis), which will ensure a deeper penetration of drugs and in larger quantities.

Ultrafrequency therapy (UHF therapy) is the influence of the electrical component of a variable (continuous or pulsed) electromagnetic field of ultrahigh frequency (from 30 to 300 MHz). For continuous oscillations, a significant contribution is made by thermal effects, the magnitude of which is due to the average field power (Figures II-2-6). In the pulsed mode of generating an electric field, the thermal effects are small, since the pauses are a thousand times greater than the pulse duration. Thus, the pulsed mode serves to enhance the specificity of the effect of the electromagnetic field on molecules.

Microwave therapy (ultrahigh-frequency electrotherapy, microwave therapy) includes the effect of electromagnetic waves of decimeter (from 1 m to 10 cm, decimeter wave (DMV) therapy) and centimeter (from 10 cm to 1 cm, centimeter-wave (SMV) therapy) ranges . Microwaves occupy an intermediate position between electromagnetic waves of the ultrahigh-frequency range and infrared rays. Therefore, for some of their physical properties, they approach the light energy.

When reflecting microwaves, especially tissues with different electrical conductivity, the incoming and reflected energy can add up, which forms so-called "standing waves", creating a threat of local overheating of tissues, for example, the subcutaneous fat layer. Part of the energy absorbed by the tissues of microwaves passes into heat and has a thermal effect.

Along with this, there is a specific oscillatory effect. It is associated with the resonant absorption of electromagnetic energy, since the vibration frequency of a number of biological molecules (amino acids, polypeptides, water) is close to the frequency range of microwaves. As a result, under the influence of microwaves, the activity of various biochemical processes increases, biologically active substances (serotonin, histamine, etc.) are formed.

In the physiological effect of the action of microwaves, two types of reactions are distinguished: local, caused mainly by local heating of tissues, and neurohumoral as a manifestation of adaptive-adaptive reactions. The maximum heat formation occurs with SMV therapy in the skin and subcutaneous fat, where the temperature can rise by 2-5 ° C. In DMV therapy, mostly water-rich tissues are heated, where the temperature can increase by 4-6 ° C with a relatively low heating of subcutaneous fat.

Local heating leads to the expansion of blood vessels, increases blood flow, reduces spasm of smooth muscles, which helps to eliminate stagnant phenomena and reduce edema. The analgesic and antipruritic effect of microwaves is associated more with the reduction of edema and the elimination of ischemia. Microwave therapy also has anti-inflammatory, antispasmodic, hyposensitizing effects. Microwave therapy is indicated for inflammatory skin diseases (furuncles, carbuncles, hydradenitis, trophic ulcers, postoperative infiltrates).

Millimeter (MMV-therapy), or extremely high-frequency (EHF-therapy) therapy is based on the use of electromagnetic waves in the millimeter range (frequency from 30 to 300 GHz, wavelength - from 10 to 1 mm). EHF-therapy is a relatively new physiotherapy method introduced into medical practice on the initiative of Academician of the Russian Academy of Sciences N.D. Devyatkova, who was one of the first to pay attention to the unusual biophysical properties of millimeter waves.

Millimeter waves are well absorbed by tissues, especially rich water, or by various hydrated molecules and supramolecular structures. Because of this, unlike decimeter and centimeter waves, millimeter waves have a low penetrating ability (up to 1 mm), which is why the primary effect of this factor is exclusively local.

In the skin, millimeter waves are capable of inducing conformational rearrangements in various structural elements, primarily in receptors, nerve conductors, and mast cells. Therefore, with EHF-therapy, preference is given to the effects on the reflexogenic zones and acupuncture points.

With EHF-therapy activation of the body's antioxidant system, which blocks the processes of lipid peroxidation, which play a key role in damage to cell membranes, is noted.

The greatest positive effect of EHF-therapy in dermatology was registered in the treatment of long-term non-healing wounds, bedsores, trophic ulcers, allergic dermatoses.

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