ELEKTROGASTROGRAFIYA

From Big Medical Encyclopedia

ELEKTROGASTROGRAFIYA [+ gaster a stomach + grapho to write, represent electro-(from «electricity»)] — a method of a research of motor activity of a stomach by means of registration of its electric potentials.

Fig. 1. Elektrogastrogramma (EGG) and in parallel the registered mekhanogastrogramma (MGG), the dogs reflecting motility of peloric department of a stomach, being in conditions of physiological hunger: synchronism of peristaltic waves on a mekhanogastrogramma and phase electric fluctuations on an elektrogastrogramma is noted; change of size of amplitudes (mV) of electric fluctuations corresponds to dynamics of changes of force of gastric reductions; points designated the intervals equal 1 min.
Fig. 2. Elektrogastrogramma, written down from a body surface of the person in 30 min. after reception of a trial breakfast, is normal also at a pyloric stenosis (the active electrode is established on an abdominal wall, in a stomach, on a midline): and — normal each tooth corresponds to a separate peristaltic wave, a rhythm of waves — 3 waves in 1 min., the average arithmetic size of amplitudes is equal to 0,3 mV; — at the patient with a pyloric stenosis (the delay of evacuation is followed by compensatory strengthening of a vermicular movement, the average arithmetic size of amplitudes is equal to 0,6 mV). Points designated the intervals equal 1 min.; at the left — calibration tension (0,25; 0,5; 1 mV).

In a wedge. to practice the elektrogastrografiya is used for identification of disturbances of motor function of a stomach at various diseases which are especially leading to a pyloric stenosis for overseeing of normalization of motor function of a stomach during treatment, differential diagnosis of a number of diseases (e.g., a pylorospasm and an inborn pylorostenosis at children), for overseeing by a physical activity of a stomach in the postoperative period. Data E. use during the studying of reactions of a stomach on patol. processes in other bodies of a digestive tract. Elektrogastrografiya in a complex with other methods of a research is applied to studying of reaction of an organism of the healthy and sick person to change of a food allowance, by exercise stresses, stay in various extreme conditions. Contraindications for E. no.

The idea of studying of secretion of a stomach on changes of biopotential of his mucous membrane belongs to V. Yu. Chagovtsu (1926). Entering a dog through a fistula of a stomach not polarized electrode, it in the course of sham feeding registered reduction of force of the entering current (Chagovts's method).

In a crust. time an elektrogastrografiya is used generally for studying of motor function of a stomach. For the first time convincing proofs of synchronous changes of mechanical and electric activity of a stomach were submitted in 1919 by the Czech physiologist I. Chermak. As a result of the researches conducted on single muscle fibers of a stomach the complexes of electric fluctuations including bystry (spaykovy) potentials are revealed (see Bioelectric potential). Further E. carried out by means of the electrode entered into a gastric cavity through a fistula or the probe. Recently as a result of development of new techniques by M. A. Sobakin E. became possible to conduct researches of motor activity of a stomach at animals in conditions hron. experience by means of the electrodes implanted in a wall of a stomach.

For a research of motor function of a stomach at people electrodes establish on a body surface, without resorting to sounding (Sobakin's method). Pilot studies are conducted on an empty stomach and during all process of digestion. At the same time synchronism of the peristaltic waves and phase electric fluctuations registered in a peloric part of a stomach is noted. Also accurate correlation between depth of peristaltic waves and amplitude of slow electric fluctuations (fig. 1) is observed. Dependence of changes E comes to light. from use various by quantity and quality of food irritants, and also from change mode and a food allowance.

In a wedge, the practician E. make by means of elektrogastrograf (EGS-1, EGS-2, EGS-3) — single-channel figurative devices with mains supply of alternating current, the main blocks to-rykh are the amplifier and the chart recorder. In a crust. time release the modernized elektrogastrograf of brand EGS-4m who is brought together according to the photocompensation scheme using the photo-electric amplifier, with double T-obrazny Bridge in a chain of a negative feed-back, having high resistance to hindrances. The eight-channel elektrogastrograf is created, to-rogo amplifiers and the filters allowing not to distort a phase ratio of the electric fluctuations which are taken away from different sites of the epigastric area that gives the chance authentically to carry out the analysis of characteristics of electric potentials of various departments of a stomach and to define localization of disturbance are a part.

Before E. investigated on an empty stomach give a trial breakfast — 100 — 150 g of white loaf, a glass of sweet to tea and one drink of suspension of barium (registration of «hungry» periodic activity of a stomach at the person by means of E. it is not effective). Then in a prone position to it carry out rentgenol. the research for the purpose of definition of the place of imposing of an active electrode, a cut shall correspond to the field of crossing of a midline of a body with a shadow of a peloric part of a stomach; sometimes the active electrode is imposed on an abdominal wall in the place of a projection of a body of a stomach or even on a hand. Depending on the provision of an active electrode register electric activity of the relevant department of a stomach; at an arrangement of an active electrode on a hand total electric activity not only a stomach, but also other internals is registered. The second electrode is imposed on the right shin. Skin in the field of imposing of electrodes is carefully degreased alcohol. During the use of EGS-1, EGS-2 and EGS-3 devices surely on the left shin of the patient impose the third (neutral) electrode on purpose zazy the line. During the use of an elektrogastrograf EGS-4m grounding of the device is made by means of the special clamp attached to it; it is strictly forbidden to ground record the patient. Keep within 30 min. in the range from 1/2 to 2 hours after reception of a trial breakfast.

At normally proceeding process of digestion electric fluctuations adequately reflect peristaltic reductions of a wall of a stomach in an elektrogastrogramma; the rhythm of electric activity precisely corresponds to a rhythm of peristaltic activity of a stomach. The healthy person has an amplitude of teeth reflecting force of reductions of a stomach in the course of digestion, varies from 0,2 to 0,4 mV. Frequency is equal 3±0,2 fluctuations in 1 min. (fig. 2, a). At various patol. states change of amplitude of teeth is observed, height to-rykh can increase to several millivolts or decrease to zero. The rhythm of electric fluctuations is stabler and, as a rule, does not undergo essential changes (fig. 2, b). According to E. it is possible to judge also evakuatorny activity of a stomach. If the steepness of increase of separate electric fluctuation is more or less steepness of his recession, then, respectively, the termination of each peristaltic wave is followed by opening or closing of the gatekeeper. Therefore, the wave in the first case will correspond to evacuation of food from a stomach, and — only to reflect hashing of contents of a stomach in the second. On dominance of this or that total activity it is possible to judge evakuatorny ability of a stomach.

On the basis of E. techniques of an elektrokolografiya, an elektroenterografiya, the electrocholecystography are developed.

Bibliography: Sobakin M. A. An experimental technique of an electrographic research of motor activity of a stomach at digestion, Bulletin ekspery. biol. and medical, t. 36, No. 3(9), page 76, 1953; it, Physical fields of a stomach, Novosibirsk, 1978; Modern questions of an elektrogastrografiya, under the editorship of M. A. Sobakin, Novosibirsk, 1975; Physiology and pathology of the alimentary system, under the editorship of V. V. Larin, M., 1963; Physiology of digestion, under the editorship of A. V. Solovyov, etc., L., 1974; Chagovets V. Yu. Observations over electric currents of a mucous membrane of a stomach of a dog, Works of the 2nd Vsesoyuz. congress fiziol., page 282, L., 1926; Tschermak A. V. Bioelektrisсhe Studien an der Magenmuskulalur, Das Elektrogastrogramm (Egg) bei Spontanrhythmik des isolierten Froschmagens, Pflugers Arch. ges. Physiol., Bd 175, S. 165, 1919.

M. A. Sobakin.

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