What causes acute gastrointestinal illness?

Predisposing factors for the development of acute gastrointestinal diseases

Group I. Anatomical and physiological features of the gastrointestinal tract

Stomachin an infant it is functionally immature. The fundus of the stomach, in the mucous membrane of which pepsin and hydrochloric acid are produced, is insufficiently developed, the pH of the gastric contents does not fall below 4.0 and only by the age of one year is 1.5-2.0. Low enzymatic activity of the stomach allows the child to digest only food that is ideal in quality and quantity, otherwise digestive disorders develop, which leads to dysfunction of the gastrointestinal tract. Low bactericidal properties of the gastric contents facilitate the development of intestinal infections.

Intestines.The main biological role of the intestinal mucosa cells is the transport of the plastic and energy ingredients of food necessary for the body. Enterocytes synthesize a large number of enzymes - lactase, invertase, maltase, esterase, ATPase, dipeptidases and others. This is a glycocalyx that covers the microvilli and, together with the enzymes associated with the microvilli membrane, plays the role of an "enzyme filter" with the help of which intensive hydrolysis and absorption occurs. With inadequate nutrition or infection of the gastrointestinal tract, small children develop a syndrome of "shorn" villi, which causes a violation of hydrolysis and absorption. In addition, the cells of the intestinal mucosa synthesize biologically active substances - serotonin, triglycerides, glycogen, some polypeptides. The gastrointestinal mucosa is a powerful organ for the transport of water and electrolytes. Urea, drugs, endogenous poisons, etc. are excreted through the gastrointestinal tract. Disruption of the latter functions in acute gastrointestinal diseases in young children leads to the development of water-electrolyte disorders and endogenous intoxication.

Blood circulation in the gastrointestinal tract is provided by a powerful vascular network. The total surface area of the intestinal capillaries alone is 10 times greater than the total surface area of the capillaries of the entire skeletal muscles. The presence of numerous anatomical shunts, an abundance of pores in the venous part of the capillaries and other features of the gastrointestinal circulation ensure complete absorption, and on the other hand, facilitate the occurrence of edema. And with edema of the interstitial space of the intestinal mucosa, diarrhea always occurs.

At the same time, the intestine is one of the organs most sensitive to oxygen starvation. It has been established that with the slightest oxygen deficiency, the absorption of glucose, amino acids and fats decreases. This explains the occurrence of digestive disorders when the systems responsible for providing tissues with oxygen - the respiratory and cardiovascular systems - are affected.

It has been established that circulatory disorders in the intestines lead to similar disorders in other organs; for example, vascular spasm may develop in the lungs and atelectasis may even occur.

Group II. Nature of feeding

The risk of getting sick with artificial feeding is 2.5-3 times higher than with natural feeding, and the mortality rate from OZhKZ with artificial feeding is 25 times higher. With mixed and artificial feeding, errors in food preparation technology are most often made, creating conditions for its microbial contamination. Almost half of children transferred to artificial feeding, during the first two months after changing the nature of nutrition, suffer from acute gastrointestinal diseases.

This group of predisposing factors also includes situations where excessive demands are placed on the enzymatic systems of the gastrointestinal tract - quantitative and qualitative overfeeding, violation of the principle of gradual introduction of new products, violation of the diet, insufficient fluid intake, etc.

Group III. State of reactivity

Features of the immune system in early childhood:

1. Imperfections of immune systems.
2. Low titer of antibodies to various microorganisms.
3. Incomplete phagocytosis.

Premature babies and those with low birth weight are especially vulnerable.

Rickets and dystrophy predispose to acute gastrointestinal diseases. These children have not only impaired defense mechanisms, but also systems regulating water-salt, carbohydrate, protein, and fat metabolism, and there are significant changes in the digestive organs, circulatory system, and central nervous system.

Frequent acute gastrointestinal diseases are observed in children suffering from immunodeficiency conditions (primary and secondary), allergies, and dysbacteriosis.

Causes and pathogenesis of acute gastrointestinal diseases

Parenteral dyspepsia is associated with acute diseases outside the gastrointestinal tract (pathology of the respiratory, cardiovascular, urinary and other systems), when the gastrointestinal tract is affected by intoxication, hypoxia, circulatory disorders, changes in the central nervous system and autonomic nervous system, impaired motility, and intestinal dysfunction appears.

Dyskinesia (spasm, atony) of various parts of the gastrointestinal tract is usually a consequence of a violation of the regulation of the tone of muscle structures in pathology of the nervous system in children, especially in perinatal encephalopathy.

The spectrum of pathogens causing intestinal infections is wide - these include bacterial flora, fungi, viruses, and recently the importance of opportunistic flora for the development of acute gastrointestinal diseases1 has been proven.

For children in the first year of life, etiological factors by frequency of detection in intestinal infections are distributed as follows:

1. rotavirus;
2. salmonella;
3. enteropathogenic Escherichia coli;
4. Proteus, Klebsiella, Cytobacter, Enterobacter, Pseudomonas;
5. Shigella.

After a year:

• shigella;
• salmonella;
• enteropathogenic E. coli; 4) rotavirus;
• campylobacter.

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Pathogenesis of acute gastrointestinal diseases

The trigger mechanism is the breakdown products of unabsorbed food ingredients (histamine-like substances, biogenic amines) in dyspepsia or microbial toxins in intestinal infections. They affect the cells of the mucous membrane, intestine, disrupt their basic functions (transport, synthesis, excretion), the activity of a number of enzymes is inhibited, "shorn villi" are formed, the process of parietal digestion is disrupted. Toxins lead to denaturation of proteins of cell membranes, which increases the permeability of the cellular barrier. This facilitates the penetration of toxins and biologically active substances formed in the intestinal lumen deep into the intestinal wall. They have a strong effect on microcirculation, first locally, and then at the level of the whole organism. Toxins increase the permeability and fragility of capillaries, congestion, submucous hemorrhages occur. Due to the resulting ischemia, oxidative processes in tissues are disrupted. The result of this is the accumulation of incomplete combustion products, lactic acid, in the outflowing blood, which leads to the development of metabolic acidosis. Similar changes in microcirculation occur in the liver. They lead to a disruption of its functions, and above all, the detoxification, barrier. Toxins pass through this barrier and flood the entire body - toxemia occurs.

As a result of blood stagnation and increased vascular permeability in the intestinal microcirculation system, water, some mineral salts and plasma albumins begin to leak from the vascular bed into the intercellular space and then into the intestinal lumen. This is the origin of loose stools in children with intestinal toxicosis, this explains the frequent watery stools, almost without feces, in children who do not receive food.

Due to water loss, dehydration of the body occurs due to circulatory, extracellular fluid, changes in the cardiovascular system appear, and hemodynamics are disrupted.

The body seems to be "looking for water" - a spasm of the skin vessels, muscles occurs - the so-called "victim of the periphery", water is extracted from the interstitial and intracellular space and "obtained" from the outside - thirst, increased reabsorption of water in the kidneys, decreased diuresis. But due to toxemia and a decrease in the volume of circulating blood, the kidneys also begin to suffer, which aggravates acidosis. Compensation for acidosis begins to be carried out by the lungs, acidotic breathing appears.

Under the influence of toxemia, hypoxia, acidosis, the function of the central nervous system suffers, the child's behavior is sharply disrupted. Hypovolemic shock may occur.

Classification of gastrointestinal diseases in young children proposed by G. N. Speransky.

1. Diseases of functional origin.

• Simple dyspepsia.
• Toxic dyspepsia.
• Parenteral dyspepsia (not registered as an independent disease).
• Pylorospasm.
• Atony of various parts of the gastrointestinal tract.
• Spastic constipation.

2. Diseases of infectious origin.

• Bacterial dysentery.
• Amoebic dysentery (amebiasis).
• Salmonellosis.
• Intestinal coli infection.
• Intestinal form of staphylococcal, enterococcal, fungal infections.
• Viral diarrhea.
• Intestinal infection of unknown etiology. 3. Malformations of the gastrointestinal tract.
• Pyloric stenosis, megaduodenum, megacolon.
• Atresia (esophagus, intestinal sections, anus).
• Other vices.

Acute course is typical for various types of dyspepsia of functional origin and for gastrointestinal diseases of infectious origin.

Currently, the infectious factor plays a major role in the occurrence of acute gastrointestinal diseases.