How to administer glucose in parenteral nutrition. Enteral and parenteral nutrition is an effective way to treat the intestines

By volume, parenteral nutrition is divided into complete and partial.

Total parenteral nutrition

Total parenteral nutrition (TPN) consists of intravenous administration all nutritional components (nitrogen, water, electrolytes, vitamins) in quantities and ratios that most closely match the needs of the body at the moment. Such food, as a rule, is necessary with complete and prolonged fasting.

The purpose of PPP is to correct violations of all types of metabolism.

Indications for total parenteral nutrition

As mentioned above, TPN is indicated for patients who cannot, should not, or do not want to eat enterally. These include the following categories of patients:

1. Patients who are unable to take or digest food normally. When diagnosing malnutrition, the presence of muscle wasting, hypoalbuminemia, protein-free edema, a decrease in the thickness of the skin fold and a significant decrease in body weight are taken into account in the patient. But isolated weight loss should not be considered a sign of malnutrition, since the presence of edema or previous obesity may mask the actual degree of endogenous nitrogen depletion.

2. Patients with an initially satisfactory state of nutrition, who temporarily (for one reason or another) cannot eat and, in order to avoid excessive exhaustion, require TPN. This is especially important when pathological conditions accompanied by increased catabolism and tissue depletion (postoperative, post-traumatic, septic patients).

3. Patients suffering from Crohn's disease, intestinal fistulas and pancreatitis. The usual diet in such patients exacerbates the symptoms of the disease and worsens general state sick. Transferring them to PPP accelerates the healing of fistulas, reduces the volume of inflammatory infiltrates.

4. Patients with a prolonged coma, when it is impossible to carry out feeding through a tube (including after operations on the brain).

5. Patients with severe hypermetabolism or significant protein losses, for example, in patients with injuries, burns (even when it is possible to carry out normal nutrition).

6. To provide nutritional support to patients receiving therapy for malignant tumors, especially when malnutrition is due to a decrease in food intake. Often the consequences of chemotherapy and radiation treatment are anorexia and inflammation of the mucous membranes of the gastrointestinal tract, which limits the possibilities of enteral nutrition.

7. It is possible to perform PPP in malnourished patients before the upcoming surgical treatment.

8. Patients with mental anorexia. PPN in such patients is necessary, since theoretically justified tube feeding under anesthesia is fraught with dangers associated not only with complications of anesthesia, but also with the possibility of pulmonary complications due to food or gastric contents entering the respiratory tract.

Partial parenteral nutrition

Partial parenteral nutrition is most often an adjunct to enteral (natural or tube) nutrition if the latter does not fully cover the deficiency nutrients arising due to such reasons as 1) a significant increase in energy costs: 2) a low-calorie diet; 3) inadequate digestion of food, etc.

Indications for partial parenteral nutrition

Partial parenteral nutrition is indicated in cases where enteral nutrition does not give the desired effect due to impaired intestinal motility or insufficient absorption of nutrients in the digestive tract, and also if the level of catabolism exceeds the energy capacity of normal nutrition.

The list of diseases in which partial parenteral nutrition is indicated:

peptic ulcer and peptic ulcer duodenum;

Pathology of the organs of the hepatobiliary system with functional liver failure;

Various forms of colitis;

Acute intestinal infections (dysentery, typhoid fever);

Pronounced catabolism in the early period after large extraperitoneal operations;

Purulent-septic complications of injuries;

Sepsis;

Hyperthermia;

Chronic inflammatory processes (lung abscesses, osteomyelitis, etc.);

Oncological diseases;

Pronounced endo- and exotoxicoses;

Severe diseases of the blood system;

Acute and chronic renal failure.

Parenteral nutrition (PN) is the introduction of nutrients necessary for the normal functioning of the body directly into the vascular bed (or other internal media). This means that nutrients administered as sterile nutritional solutions enter directly into the bloodstream and bypass the gastrointestinal tract.

In this article, we will acquaint you with indications and contraindications, types, options and rules of administration, possible complications and parenteral nutrition products. This information will help you get an idea of ​​this method of nutrient delivery, and you can ask your doctor any questions you may have.

The goals of PP prescription are aimed at restoring and maintaining the acid-base and water-electrolyte balance and providing the body with all the necessary energy and building components, vitamins, micro- and macroelements. There are 3 main concepts of such nutrition. According to the "European concept", created in 1957 by Dr. A. Wretlind, and the "American concept", developed in 1966 by S. Dudrick, various drugs for PP are introduced separately according to different principles. And according to the "all in one" concept, created in 1974, all the necessary fat emulsions, electrolytes, amino acids, vitamins and monosaccharides are mixed before injection. Now, in most countries of the world, experts prefer just such an introduction of funds for PP, and if it is impossible to mix any solutions, their intravenous infusion is performed in parallel with the use of a V-shaped conductor.

Kinds

PP can be:

• complete (or total) - all the necessary substances come only in the form of infusion solutions;
• additional - this method complements tube or oral nutrition;
• mixed - simultaneous combination of enteral and parenteral nutrition.

Indications

PP can be appointed in the following cases:

• the impossibility of administering nutrients by oral or enteral route for a week in stable patients or at a shorter time in patients with malnutrition (usually with impaired functioning of the digestive organs);
• the need to temporarily stop the digestion of food in the intestines (for example, the creation of a "rest mode" with);
• significant protein losses and intense hypermetabolism, when enteral nutrition cannot compensate for nutrient deficiencies.

Contraindications

PP cannot be performed in the following clinical cases:

• there is the possibility of introducing nutritional components in other ways;
• on the drugs used for PP;
• the impossibility of improving the prognosis of the disease by conducting PP;
• a period of electrolyte disturbances, shock reactions or hypovolemia;
• categorical refusal of the patient or his guardians.

In some of the cases described above, the use of PP elements is acceptable for intensive care.

How drugs are administered

For PP, the following routes of administration (or accesses) can be used:

• by infusion into a peripheral vein (through a catheter or cannula) - usually carried out if such a method of nutrition is necessary for 1 day or with additional administration of the drug against the background of the main PP;
• through a central vein (through a temporary or permanent central catheter) - performed if it is necessary to provide a longer PN;
• alternative vascular or extravascular access (peritoneal cavity) - are used in more rare cases.

With a central approach, PP is usually performed through the subclavian vein. In more rare cases, drugs are injected into the femoral or jugular vein.

For PP, the following modes of administration can be used:

• cyclic administration for 8-12 hours;
• prolonged administration for 18-20 hours;
• round the clock introduction.

The main types of drugs

All funds for PP are usually divided into two main groups:

• donators of plastic material - amino acid solutions;
• energy donators - fat emulsions and solutions of carbohydrates.

Osmolarity of drugs

The osmolarity of the solutions administered during PN is the main factor that must be taken into account in this method of nutrition. It must be taken into account in order to avoid the development of hyperosmolar dehydration. In addition, when using high-osmolar solutions, the risk of phlebitis should always be taken into account.

The osmolarity of human plasma is 285-295 mosm/l. This means that only solutions whose osmolarity is close to such physiological parameters can be injected into the peripheral blood. That is why, when performing PP, preference is given to the central veins, since the vast majority of drugs used have higher osmolarity values, and the introduction of substances with an osmolarity of more than 900 mosm/l into the peripheral vein is categorically contraindicated.

Limits of maximum infusions

When conducting PP, the rate of receipt of solutions depends on the patient's condition and is regulated by his body. When prescribing such drugs, the doctor solves the problem assigned to him and strictly observes the maximum daily dosages and the rate of administration of drugs for PP.

The maximum rate of entry of solutions for PP into the vein is as follows:

• carbohydrate - up to 0.5 g / kg / h;
• amino acids - up to 0.1 g / kg / h;
• fat emulsions - 0.15 g / kg / h.

It is desirable to carry out the infusion of such drugs for a long time or use automatic devices - infusion pumps and line machines.

Principles of parenteral nutrition

For an adequate PP, the following rules must be observed:

1. Solutions of drugs should enter the body in the form of components necessary for the metabolic needs of cells (i.e., in the form of such nutrients that have already passed the enteral barrier). For this, proteins, carbohydrates and fats are used in the form of amino acids, monosaccharides and fat emulsions.
2. Infusions of high-osmolar drugs are performed exclusively in the central veins.
3. When conducting an infusion, the rate of administration of infusion solutions is strictly observed.
4. Energy and plastic components are introduced simultaneously (all essential nutrients are used).
5. Systems for intravenous infusion must be replaced with new ones every 24 hours.
6. The fluid requirement is calculated for a stable patient at a dose of 30 ml/kg or 1 ml/kcal. In pathological conditions, the dose is increased.

Amino acid solutions

There are practically no reserves of protein in the body, and under conditions of intense metabolic stress, a person quickly develops protein-energy malnutrition. Previously, protein hydrolysates, blood, plasma and albumin were used to replenish lost proteins, but they had a low biological protein value. Now, solutions of L-amino acids are used to compensate for the lack of proteins in PP.

The body's need for such substances is determined by the severity of metabolic stress, and the dosage of drugs for PP ranges from 0.8-1.5 g/kg, and in some cases reaches up to 2 g/kg. The introduction of higher doses by most specialists is considered inappropriate, since such dosing will be accompanied by adequate utilization of proteins. The rate of administration of these drugs should be 0.1 g/kg per hour.

The volume of administered amino acid solutions is always determined by the need to achieve a positive nitrogen balance. Such substrates are used exclusively as a plastic material, and therefore, when they are introduced, an infusion of energy-donating solutions is necessarily carried out. 120-150 non-protein (fat and carbohydrate) kilocalories of energy carriers are added per 1 g of nitrogen.

Pharmaceutical companies produce amino acid formulations of drugs for PN, guided by different principles. A number of solutions are created on the basis of the “potato-egg” amino acid composition that has the highest biological value, while other preparations contain all the essential amino acids.

Additionally, the composition of amino acid solutions can be introduced:

• electrolytes;
• vitamins;
• succinic acid;
• energy carriers - xylitol, sorbitol.

There are no absolute contraindications for the use of such protein preparations. Their use is relatively contraindicated in the following cases:

• acidosis leading to impaired utilization of amino acids;
• in need of fluid restriction;
• progressive severe liver pathologies (but in such cases only specialized solutions can be used).

Standard amino acid solutions

The composition of such funds includes essential and some non-essential amino acids. Their ratio is dictated by the normal needs of the body.

Usually 10% solutions are used, 500 ml of which contain 52.5 g of protein (or 8.4 g of nitrogen). These standard amino acid solutions include the following drugs:

• Aminoplasmal E;
• Aminosteril KE;
• Vamin.

In some protein preparations, the concentration is from 5.5 to 15%. Low-percentage solutions (Infezol 40, Aminoplasmal E 5% and Aminosteril III) can be injected into peripheral veins.

Specialized amino acid solutions

These drugs contain a modified amino acid composition.

There are such specialized solutions of amino acids:

• with a high content of branched chain amino acids and a low content of aromatic amino acids - Aminoplasmal Hepa, Aminosteril N-Hepa;
• including predominantly essential amino acids - Aminosteril KE-Nefro.

Energy donors

The group of these funds for PP include:

• fat emulsions;
• carbohydrates are alcohols and monosaccharides.

Fat emulsions

These funds are the most profitable energy providers. Typically, the calorie content of 20% fat emulsions is 2.0, and 10% - 1.1 kcal / ml.

Unlike carbohydrate solutions for PP, fat emulsions have a number of advantages:

• less likely to develop acidosis;
• high calorie content even at small volumes;
• lack of osmolar action and low osmolarity;
• reduction of fat oxidation processes;
• the presence of fatty acids.

The introduction of fat emulsions is contraindicated in the following cases:

• shock state;
• DIC;
• hypoxemia;
• acidosis;
• microcirculation disorders.

Three generations of fat emulsions are used for PP:

• I - long-chain emulsions (Lipofundin S, Liposan, Lipovenoz, Intralipid);
• II - medium chain fatty acids (or triglycerides);
• III - emulsions with a predominance of Omega-3 fatty acids (LipoPlus and Omegaven) and structured lipids (Structolipid).

The rate of administration of 20% emulsions should not exceed 50 ml/hour, and 10% - no more than 100 ml/hour. The usual ratio of fats and carbohydrates administered during PP is 30:70. However, this proportion can be changed and brought up to 2.5 g/kg.

The limit of the maximum infusion of fat emulsions must be strictly observed and be 0.1 g / kg / h (or 2.0 g / kg / day).

Carbohydrates

It is carbohydrates that are most often used in the clinical practice of PN. For this, the following solutions can be prescribed:

• glucose - up to 6 g / kg / day at an injection rate of 0.5 g / kg / h;
• Invertase, fructose, Xylitol, Sorbitol - up to 3 g / kg / day at an injection rate of 0.25 g / kg / h;
• Ethanol - up to 1 g / kg / day at an injection rate of 0.1 g / kg / h.

With partial PP, the dosage of carbohydrates is reduced by 2 times. At maximum doses without fail, make a break in the introduction for 2 hours.

Vitamins and trace elements

Correction of the deficiency of such substances is carried out as necessary for various pathologies. The following preparations can be prescribed as vitamin and microelement solutions for PP:

• Vitalipid - is administered together with fat emulsions and contains fat-soluble vitamins;
• Soluvit N - mixed with a solution of glucose and contains a suspension of water-soluble vitamins;
• Cernevit - is administered with a glucose solution and consists of a mixture of water- and fat-soluble vitamins;
• Addamel N is mixed with amino acid solutions Vamin 14 or 18 without electrolytes, Vamin with glucose, Vamin 14 or with glucose at a concentration of 50/500 mg/ml.

Two- and three-component solutions

The composition of such funds includes amino acids, lipids, glucose and electrolytes selected in the required proportions and doses. Their use has a number of significant advantages:

• ease and safety of use;
• simultaneous administration;
• reducing the likelihood of infectious complications;
• economic benefit;
• the possibility of adding additional vitamin and microelement agents.

Such solutions are placed in plastic all-in-one systems and are separated from each other by sections, which, when using the drug, are effortlessly destroyed by the usual twisting of the bag. In this case, all components of the drug are easily mixed with each other and form a milk-like mixture. As a result, all PN solutions can be administered simultaneously.

Two- and three-component solutions for PP include the following drugs:

• Nutriflex special - contains amino acids and glucose solution;
• OliClinomel No 4-550E - intended for administration into peripheral veins, contains electrolytes in an amino acid solution and calcium in a glucose solution;
• OliClinomel No 7-1000E - intended for injection only into the central veins, contains the same substances as OliClinomel No 4-550E;
• OliClinomel - in three sections of the bag contains an amino acid solution, a fat emulsion and a glucose solution, it can be injected into peripheral veins.

Monitoring the patient's condition during parenteral nutrition

Patients on PN are regularly monitored for the following blood test parameters:

• sodium, potassium, chlorine;
• coagulogram;
• creatinine;
• triglycerides;
• albumen;
• urea;
• bilirubin, ALT and AST;
• magnesium, calcium, zinc, phosphorus;
• B12 (folic acid).

The following parameters are monitored in the patient's urine:

• osmolarity;
• sodium, potassium, chlorine;
• urea;
• glucose.

The frequency of analysis is determined by the duration of the PN and the stability of the patient's condition.

In addition, indicators are monitored on a daily basis. blood pressure, pulse and respiration.

Possible Complications

With PP, the following complications may develop:

• technical;
• infectious (or septic);
• metabolic;
• organopathological.

Such a distinction is sometimes conditional, since the causes of complications can be combined. However, the prevention of their occurrence always consists in regular monitoring of homeostasis indicators and strict observance of all the rules of asepsis, technique for setting up and caring for catheters.

Technical complications

These consequences of PP occur when access is incorrectly created for the introduction of nutrient solutions into the vessels. For example:

• and hydrothorax;
• tears in the vein into which the catheter is inserted;
• embolism and others.

To prevent such complications, strict adherence to the technique of installing an intravenous catheter for PN is necessary.

Infectious complications

Such negative consequences of PN in some cases are caused by improper operation of the catheter or non-compliance with asepsis rules. These include:

• catheter thrombosis;
• catheter infections leading to angiogenic sepsis.

Prevention of these complications consists in observing all the rules for caring for an intravenous catheter, using protective films, siliconized catheters, and constantly observing the rules of strict asepsis.

Metabolic Complications

These consequences of PN are caused by improper use of nutrient solutions. As a result of such errors, the patient develops homeostasis disorders.

With improper administration of amino acid compositions, the following pathological conditions may occur:

• respiratory disorders;
• azotemia;
• mental disorders.

With improper administration of carbohydrate solutions, the following pathological conditions may occur:

• hyper or;
• hyperosmolar dehydration;
• glycosuria;
• phlebitis;
• violations of the liver;
• respiratory dysfunction.

With improper administration of fat emulsions, the following pathological conditions may occur:

• hypertriglyceridemia;
• drug intolerance;
• lipid overload syndrome.

Organopathological complications

Incorrect PN can lead to organ dysfunction and is usually associated with metabolic disorders.

The problem of the safety of a critically ill patient today occupies a leading place in all areas of intensive care and anesthesiology, since often not insufficiently effective, but rather insufficiently safe use of intensive care methods nullifies all the efforts of medical personnel to achieve a result.

Of course, nutrition as an integral component of intensive care can also cause harm through various factors. This is especially true for the parenteral route of nutrient administration.

Without a doubt, from the point of view of safety, it is necessary to drink and eat through the mouth, since this is inherent in human physiology, respectively, if possible, the introduction of fluids, electrolytes, macro- and micronutrients should be carried out in a natural way.

• it supports the structure of the intestinal villi;
• stimulates the secretion of brush border enzymes, endopeptides, immunoglobulin A, bile acids;
• preserves the integrity of the joints of the intestinal epithelium;
• reduces the permeability of the intestinal epithelium;
• prevents bacterial translocation.

• intestinal starvation;
• increased frequency of infectious complications;
• metabolic complications;
• immunological complications;
• organ dysfunction.

Obvious problems with total parenteral nutrition (TPN) include hyperglycemia (up to 50% of cases), hypertriglyceridemia (25-50% of cases) and septicemia, which occurs 2.8 times more often with TPN.

According to the latest guidelines European Society parenteral and enteral nutrition (ESPEN), which includes Russia, “starvation or malnutrition of patients in the intensive care clinic increases the mortality rate (category C), respectively, parenteral nutrition can be started in patients who cannot be in the next 24 hours Enteral nutrition is initiated (Category B) and in malnourished patients who cannot receive adequate oral or enteral nutrition (Category C).”

At the beginning of the XXI century. For several years, the topic of death from parenteral nutrition has been discussed in the literature. The authors attributed to parenteral nutrition such problems as atrophy of the gastrointestinal mucosa, bacterial overgrowth, bacterial translocation, atrophy of intestinal lymphoid tissue, and a decrease in the level of immunoglobulin A in secret. respiratory tract, decreased immunity, as well as hepatic steatosis and liver failure.

However, the dangers of parenteral nutrition in general are greatly exaggerated, and here's why. In contrast to animal data, there is no convincing evidence that parenteral nutrition in humans leads to atrophy of the gastrointestinal mucosa, intestinal lymphoid tissue, bacterial overgrowth and translocation, even in critical conditions. In addition, the previously observed negative effects of total parenteral nutrition could be the result of hypercaloric content and excess glucose, as well as the imperfection of parenteral nutrition technology.

It should be noted that the comparison and even more so the opposition of the parenteral and enteral route of administration is incorrect, which was brilliantly demonstrated in the largest European epidemiological study, which included more than 100 thousand patients on parenteral nutrition (including children and newborns) from a sample of more than 11 million case histories for the period 2005-2007. It turned out that patients receiving parenteral nutrition, in all respects, are more likely to die than patients on enteral nutrition. Attention should also be paid to the nosological characteristics of patients on parenteral nutrition.

Conclusion 1. Parenteral and enteral nutrition cannot be compared.

When talking about the dangers of parenteral nutrition, it also seems incorrect to refer to studies that used the strategy of hyperalimentation, providing calories mainly due to glucose, parenteral nutrition preparations of older generations.

Thus, in 2006, a randomized controlled trial (n=326) was conducted, which compared the effect of modern "immune" enteral nutrition with modern parenteral nutrition. According to the results obtained, mortality did not differ between groups, the duration of treatment in the ICU and the incidence of infections were less in the group of patients with "immune" enteral nutrition (17.6 vs 21.6 days and 5 vs 13%, respectively).

Conclusion 2. Speaking about the dangers of parenteral nutrition, it is necessary to remember that nutrients and parenteral nutrition technologies are improving.

Among the reasons for the decrease in the number of complications of parenteral nutrition, the following should be highlighted:

• improved solution formulas;
• application of all-in-one systems;
• applying a glycemic control strategy and limiting glucose use;
• improved vascular access care.

When discussing the safety of parenteral nutrition, the following issues should be highlighted:

1. Calorie safety: how many calories are safe?
2. Composition safety: what is safe to feed?
3. Volume safety: what volume of the formula corresponds to the calorie content and composition?
4. Osmotic and metabolic safety: what is the safe rate of administration?
5. Which is safer: vials or all-in-one systems?
6. Problems of compatibility and stability of solutions for parenteral nutrition: how to safely mix nutrients?
7. What is the optimal level of glycemia and should insulin be administered when using solutions for parenteral nutrition?
8. Infection safety: how to reduce the number of infectious complications when using solutions for parenteral nutrition?

Before considering all the questions raised point by point, I would like to turn to one of the examples of complications of parenteral nutrition - liver dystrophy (Parenteral Nutrition Associated Liver Disease, PNALD). Among its reasons are:

• hypercaloric nutrition (calorie safety);
• excess carbohydrates (composition safety);
• lack of fat (composition safety);
• amino acid imbalance (excess methionine) (composition safety);
• excess phytosterols (composition safety);
• violation of the circulation of bile acids during parenteral nutrition.

Calorie Safety: Isocaloric or Hypocaloric?

One of clear examples The dangerous use of hypercaloric nutrition is the so-called refeeding syndrome (“refeeding syndrome”), which was described even in released prisoners of concentration camps with an active onset and excess enteral nutrition. This syndrome is characterized by the development of severe multiple organ failure, primarily cardiovascular failure with the development of shock, acute respiratory failure, acidosis, rhabdomyolysis, cerebral edema, neurological disorders, muscular dystrophy, thrombocytopenia, etc.

Therefore, the basic principle of calorie safety sounds like this: start low go slow, that is, you should start with an incomplete calculated calorie intake and increase it gradually to the calculated one within 2-3 days.

To date, the harm from hypercaloric nutrition has been reliably established. For example, JP Barret et al., studying the autopsy data of 37 children who died as a result of a burn disease, who used hypercaloric nutrition, in 80% of cases found fatty infiltration of the liver and an increase in its mass 2 times higher than normal, as well as an increase in the incidence of sepsis. (R<0,001).

In the study by S. Dissanaike et al. it was found that hypercaloric parenteral nutrition leads to a significant increase in the frequency of bloodstream infections, and the more calories, the higher the percentage of complications. At the same time, while ensuring the normocaloric content (less than 25 kcal/kg), the frequency of bloodstream infections is low (less than 10%).

There is still no consensus on some issues of calorie safety: is it necessary to monitor metabolic needs on a daily basis and provide calorie intake in accordance with them, or are calculation equations sufficient? Is it necessary to provide 100% of the demand (calculated or measured?) or is it enough to give some smaller amount of food, and if less, then how much (50, 60, 80%?).

Paradoxically, total parenteral nutrition seems to be the most acceptable from the point of view of calorie safety: compared to the natural way of nutrition, enteral nutrition and various combinations (including combinations with parenteral nutrition), the frequency of "underfeeding" and "overfeeding" is minimal when using it.

The greatest "underfeeding" was observed when patients were fed by mouth (up to 80% of patients received less than 80% of the main metabolism), and the greatest "overfeeding" was observed with a combination of oral nutrition and enteral nutrition (up to 70% of patients received more than 110% of the main metabolism).

Not only "underfeeding", but also "overfeeding" is dangerous for the patient, so it is advisable to use strict calorie control, in the absence of calorie control - 20-30 kcal / kg / day (for obesity - calculation for ideal body weight), to ensure isocaloric regimens often require parenteral nutrition or a combination of parenteral and enteral nutrition.

Volume Security

Several well-designed studies have demonstrated that the choice of volume of fluid therapy in the treatment of shock and in the subsequent days of treatment significantly affects the prognosis. Under-infusion in the treatment of shock and excess fluid in the following days results in the worst outcome.

From the point of view of the safety of the volume of parenteral nutrition, there are some points to remember:

• The restrictive strategy of infusion therapy dictates the need to reduce the amount of parenteral nutrition.
• All-in-one systems are preferred when infusion volume is limited.
• Commercial all-in-one systems have different volumes and different ratios of calories and nutrients in one volume!

Osmotic safety

According to the 2009 ESPEN recommendations, the administration of high osmolar parenteral nutrition solutions designed to provide the body with nutrients requires the installation of a central venous access (category C); the installation of a peripheral venous access is considered if the introduction of low-osmolar (<850 мосмоль/л) растворов, предназначенных для проведения парентерального питания с целью частичного удовлетворения нутритивных потребностей и предотвращения возникновения отрицательного баланса энергии (категория С).

Mixtures of solutions with a final osmolarity of more than 850 mosmol / l should be injected into the central veins within 12-24 hours!

Formula safety: glucose and glycemic control

Glucose is an essential macronutrient and without it, adequate nutrition is not possible. Nevertheless, hyperglycemia, which often occurs in critically ill patients and, naturally, is often observed with parenteral administration, is characterized by a number of negative effects, most of which have been studied in patients with diabetes mellitus: impaired wound healing, anastomoses, inhibition of platelet aggregation, thrombocytopenia, glycation of immunoglobulins, decreased phagocytosis, protein catabolism and gluconeogenesis, which are of key importance in metabolic disorders in hyperglycemia.

The main metabolic consequences of hyperglycemia, which ultimately lead to complications and adverse outcomes, should be kept in mind. These effects include protein catabolism, increased hepatic gluconeogenesis from amino acids from degraded muscle, insulin resistance, and a reduced effect of insulin as a muscle anabolic.

In connection with the negative effects of hyperglycemia on the body as a whole and, first of all, on protein synthesis, the following should be remembered to ensure the safe use of parenteral nutrition solutions:

• when conducting parenteral nutrition, the concentration of blood glucose should be monitored;
• to maintain normoglycemia, it is necessary to use insulin infusion;
• the amount of glucose should not exceed 4-5 g / kg / day, and the rate of administration - 0.5 g / kg / h;
• commercial all-in-one systems have different amounts of glucose (different utilization rates, different risk of hyperglycemia, liponeogenesis, and protein catabolism).

Ingredients Safety: Amino Acids and Protein

According to the 2009 ESPEN guidelines, “if a patient is indicated for parenteral nutrition, a balanced amino acid solution should be administered at a rate that provides amino acids in the amount of 1.3-1.5 g/kg of ideal body weight per day, in combination with administration of an adequate amount of energy substrates (class B)”.

The balance of the amino acid solution implies the presence of 19 amino acids, including all essential amino acids, while the essential / nonessential ratio is about 1, the essential / total nitrogen ratio is about 3, the leucine / isoleucine ratio is more than 1.6; the presence of glutamic acid is also important.

The use of a balanced solution of amino acids containing glutamic acid (glutamate) allows you to increase the plasma concentration of the conditionally essential amino acid glutamine and reduce protein catabolism.

According to the 2009 ESPEN guidelines, "if the ICU patient is indicated for parenteral nutrition, the amino acid solution should contain L-glutamine in such an amount that the patient receives 0.2-0.4 g/kg of glutamine per day." Since L-glutamine is a poorly soluble amino acid and precipitates in an amino acid solution, it is possible either to use a balanced amino acid solution containing glutamic acid or to add glutamine dipeptides to the amino acid solution.

In addition, as noted above, ensuring normoglycemia, a positive nitrogen balance, and sufficient amounts of essential nutrients can also eliminate the need for exogenous glutamine.

Formula safety: fat emulsions

Parenteral nutrition of critically ill patients is impossible without the use of fat emulsions. There are several reasons for this.

• First, fat emulsions are the only source of essential fatty acids and phospholipids, which serve as a building material for cell membranes, precursors of mediators and hormones.

• Secondly, being a high-energy substrate, they avoid excess glucose, thus preventing the growth of glycemia and reducing the respiratory quotient (RQ).

• Thirdly, some classes of fatty acids (omega-3) are credited with a number of "healing" properties.

However, in critically ill patients (especially with sepsis), attention should be paid to the following metabolic features: an increase in lipid oxidation compared with patients after elective surgery, in which glucose oxidation predominates.

All this is reflected in the 2009 ESPEN guidelines: “Lipids should be an integral part of parenteral nutrition as a source of energy and a guaranteed supply of essential fatty acids in critically ill patients (category B).”

Doctors with more than 30 years of experience remember what side effects accompanied the parenteral use of fat emulsions: pyrogenic reactions, fat embolism, respiratory distress syndrome, so they often refuse to prescribe drugs of this class.

In this regard, in the medical environment there are a number of myths about the dangers of fat emulsions - myths about fat overload, thermogenesis, ketoacidosis. Fat overload, which can occur with excess linoleic acid, was observed with the first fat emulsions based on cottonseed oil, while using 2nd (MCT / LCT) and 3rd (LCT / MCT / omega-3) fat emulsions of these there are no problems.

A pyrogenic reaction can occur with the introduction of emulsions of all generations in the event of a violation of the rate of administration or a violation of the metabolism of fatty acids (carbohydrate deficiency, hypoxia, shock), when the rate of administration exceeds the rate of utilization in the body. It should be noted that if all the rules for the safe introduction of fat emulsions are observed, these and many other problems do not arise.

Some physicians believe that ketoacidosis occurs with the use of medium chain triglycerides (MCTs), however, studies of the acid-base status with the use of MCT emulsions in all age groups, including preterm infants, have not found a change in acid-base status. An increase in blood ketone bodies when using fat emulsions is a natural phase of their metabolism.

For the safe administration of fat emulsions, it is necessary to remember the maximum dose and the maximum rate of their administration, which should not exceed the rate of utilization from the vascular bed.

According to the 2009 ESPEN guidelines, "intravenous fat emulsions (MCT, LCT, or mixtures of emulsions) may be administered at a dose of 0.7-1.5 g/kg over 12-24 hours", i.e. the rate of administration of the emulsion should not exceed 100 ml/h! The second key aspect of the safe use of fat emulsions is the stability of the solution when mixed with other components of parenteral nutrition.

It should also be remembered that some of the disadvantages of the first generation of fat emulsions containing only long chain triglycerides (LCT) (based on soybean oil) are slow utilization from the bloodstream, excessive load on mononuclear phagocytes, overload of the reticuloendothelial system, overload of the pulmonary circulation in patients with acute respiratory distress syndrome, leading to an increase in pressure in the pulmonary circulation and a decrease in the oxygenation index, liver damage leading to an increase in transaminases, bilirubin, as well as a pro-inflammatory effect and dysfunction of cell membranes due to the dominance of omega-6 fatty acids. Despite these shortcomings, the main role of LCT is to provide the body with essential fatty acids.

Compared to LCTs, medium chain triglycerides (MCTs) (source e.g. coconut oil) have 100 times higher water solubility, are more resistant to lipid peroxidation processes, do not require carnitine and transport proteins to enter the cell, so they are 2 times faster consumed from the bloodstream, do not cause lipid overload, do not disrupt the functions of the reticuloendothelial system and do not create an additional load on the mononuclear system, do not cause damage to the lung endothelium and have a protein-saving effect.

The main role of MST is an energy substrate. The isolated administration of MCT emulsions is not possible because, despite all their advantages, LCT emulsions are a source of essential fatty acids.

The 2009 ESPEN guidelines state: “MCT/LCT fat emulsions are recommended for critically ill patients along with LCT, olive oil and fish oil preparations (category B); there is evidence of better clinical tolerability of MCT/LCT fat emulsions compared to pure LCT emulsions (Category C).”

The recommendations of the German Society for Nutritional Medicine (DGEM) give more preference to emulsions of the 2nd (MCT/LCT) and 3rd (MCT/LCT/fish oil + olive oil) generations: “In critically ill patients, the introduction of MCT/LCT is recommended; in patients with severe sepsis or septic shock, 30-50% of non-protein calories should be supplied from lipids using fat emulsions that are a mixture of LCT and MCT, LCT and olive oil, MCT + olive oil and fish oil.”

Although omega-3 fatty acids have a range of beneficial effects, it should be noted that omega-3s alone (without LCT, LCT/MCT, or LCT/olive oil) are not safe because they are poorly hydrolyzed by lipoprotein lipase and therefore may accumulate in the circulatory system.

Moreover, the combination of omega-3 and LCT emulsions is also unsafe due to inhibition of the release of fatty acid emulsion from soybean oil by omega-3 acids, which can lead to accumulation of the emulsion in the vascular bed. The combination of omega-3 fatty acids and MCT normalizes the hydrolysis of lipoproteins, increases the rate of utilization of fatty acids and prevents the development of fat overload.

That is why the 3rd generation of fatty acids necessarily includes three components: LCT as a source of essential fatty acids, MCT as a rapidly metabolized energy substrate that improves lipoprotein hydrolysis when combined with LCT, and omega-3 fatty acids with an immunomodulatory effect.

Mixing safety of fat emulsions: the problem of stability

One of the fundamental points in terms of the safety of the use of fat emulsions and the use of their combination with other components of parenteral nutrition is the stability of the fat emulsion.

According to one of the strictest pharmacopoeias of the world - American (USP), the average size of a fat globule in a solution for parenteral administration should not exceed 0.5 microns (1/10 of the diameter of the pulmonary capillary), and the proportion of large globules should not exceed 5 microns (PFAT 5) (which is comparable to the diameter of an erythrocyte and the diameter of a pulmonary capillary!) - no more than 0.05%.

It is known that the use of “unstable” lipids, that is, lipids with a violation of the emulsion structure and aggregation of fat globules, leads to blockage of the pulmonary capillaries, damage to the endothelium of the lungs, severe leukocyte infiltration of the lung tissue with the development of acute lung damage.

There are several factors that affect the destabilization of the fat emulsion. Firstly, the destabilization of the emulsion begins when the integrity of the original packaging is violated during the installation of the infusion system (dropper) and progresses over time.

At the same time, the development time of an unstable fat emulsion depends on the qualitative composition of the emulsion. So, emulsions based on soybean oil (first generation - LCT emulsions) or combinations of soybean and safflower oils become unstable after 12 hours and after a day the proportion of large globules reaches 1%, which is 20 times higher than the permissible values. And emulsions based on a combination of MCT and soybean oil or olive and soybean oils remain stable even 30 hours after the start of the infusion!

Secondly, the stability of fat emulsions in glass bottles and plastic bags "all in one" can be fundamentally different. So, in the study by D. F. Driscoll et al. all claimed emulsions in glass vials (Intralipid 10%, ClinOleic 20%, Structolipid 20%, Lipoplus 20%, Lipofundin MCT/LCT 10%, Lipofundin MCT/LCT 20%) were stable (PFAT 5 less than 0.05%), however The stability of fat emulsions in a plastic bag or when mixing emulsions in all-in-one systems exceeded acceptable values ​​if they were based on soybean oil, but remained normal when they contained a combination of MCT/LCT (coconut and soybean oils).

Thirdly, the stability of a fat emulsion in a vial does not mean that it is stable when mixed with other parenteral nutrition components. This applies to both mixing in all-in-one systems and mixing during infusion when using a bottled parenteral nutrition technique.

The main factors affecting the stability of the finished mixture of parenteral nutrition are:

• divalent cations (calcium, magnesium);
• dissolved oxygen;
• daylight;
• trace elements.

For the safe use of parenteral nutrition, the following mixing order must be followed in all-in-one systems:

1. first add electrolytes (if necessary, water-soluble vitamins and trace elements) to the amino acid solution;
2. then add glucose;
3. then add a fat emulsion (if necessary with fat-soluble vitamins added to it, which are safer to administer separately).

The use of "all in one" systems is safer when using fat emulsions of the 2nd and 3rd generations and following the rules for mixing solutions than the "bottle method".

Serious complications of parenteral nutrition include bloodstream infections. All-in-one systems reduce the risk of developing bloodstream infections. So, P. Wischmeyer et al. compared the use of all-in-one systems with the "bottle technique" of parenteral nutrition in 31,129 patients in 182 hospitals: the incidence of bloodstream infections with the "bottle technique" was 8.1% higher than with the use of "all-in" systems. one" (35.1 vs 43.2%, p<0,001).

According to randomized controlled trials, up to 80% of patients receiving parenteral nutrition can be provided with standard parenteral nutrition using all-in-one systems, and only 20% of patients require metabolically oriented nutrition according to an individual modular scheme.

Conclusion

The problem of safety of parenteral nutrition should be considered somewhat broader than the use of certain solutions for parenteral nutrition, as well as the use of special pharmaconutrients.

This issue should address calorie content, the qualitative and quantitative composition of parenteral nutrition, the effect on metabolism, storage, mixing, and infectious safety.

The use of modern all-in-one systems, subject to the rules of storage, mixing and administration of parenteral nutrition and infection control drugs, is safe for the patient.

B. R. Gelfand, A. I. Yaroshetsky, O. A. Mamontova, O. V. Ignatenko, I. Yu. Lapshina, T. F. Grinenko

Enteral nutrition is a type of therapeutic or supplementary nutrition with special mixtures, in which the absorption of food (when it enters through the mouth, through a probe in the stomach or intestines) is carried out in a physiologically adequate way, that is, through the intestinal mucosa. In contrast, parenteral nutrition is distinguished, in which mixtures are injected through a vein into the blood.

Liquid or tube feeding (enteral nutrition) is also called elemental or astronaut nutrition. We are talking about liquid mixtures of various compositions that were developed for space flights. Then these technologies began to be used in the development of special preparations for therapeutic nutrition.

The basis of such a meal is a mixture of products freed from toxins (fiber, cell membranes, connective tissue), crushed to a powdery state, balanced in chemical composition.

They contain various products in the form of monomers, dimers and partly polymers. According to the physico-chemical state, these are partly true, and partly colloidal solutions. The daily portion usually contains all the nutrients necessary for life: proteins, fats, carbohydrates, mineral salts, trace elements and vitamins within the physiological norm.

With this type of nutrition, the principle of mechanical sparing of the intestine is most fully realized. Some elemental diets exclude foods to which an intolerance has been established (cereals, dairy products, yeast).

Now there are mixtures with different tastes and with the presence or absence of ballast substances (fiber). The presence of fiber in mixtures should be paid attention to in case of stenosis (narrowing) of the small intestine, as it can clog the narrow lumen of the intestine.

So-called elemental (low molecular weight) diets are also prescribed. These are easily digestible mixtures that are already absorbed in the upper part of the small intestine. They are used for severe inflammation of the intestine, because the more inflammation, the more the absorption process in it is disturbed.

In elemental mixtures, substances are presented in an already “digested” form. For example, protein is in the form of amino acids. This state of the elements makes them taste unpleasant.

In addition, there are mixtures with a limited fat content. They provide a reduction in their absorption.

When is enteral nutrition used?

This therapy is prescribed during a period of severe exacerbation in inflammatory bowel diseases and in malabsorption diseases.

In an exacerbation of Crohn's disease in children, it has been proven that the use of enteral nutrition (elemental diet) for 6-8 weeks is more effective than treatment with corticosteroids (cortisone). Therefore, in the treatment of children, preference is given to diets. No differences in efficacy were found between low molecular weight and high molecular weight diets.

In adult studies, no superiority of diet over cortisone therapy has been established. In addition, adults are less disciplined and do not follow a strict diet.

The Ministry of Health of the Russian Federation has developed “Instructions for the organization of enteral nutrition ...”, which indicates the following indications for its use:

1. Protein-energy malnutrition when it is impossible to provide adequate intake of nutrients through the natural oral route.
2. Neoplasms, especially localized in the head, neck and stomach.
3. Disorders of the central nervous system: coma, cerebrovascular stroke or Parkinson's disease, as a result of which nutritional status disorders develop.
4. Radiation and chemotherapy in oncological diseases.
5. Diseases of the gastrointestinal tract: Crohn's disease, malabsorption syndrome, short bowel syndrome, chronic pancreatitis, ulcerative colitis, diseases of the liver and biliary tract.
6. Nutrition in the pre- and early postoperative periods.
7. Trauma, burns, acute poisoning.
8. Complications of the postoperative period (fistulas of the gastrointestinal tract, sepsis, anastomotic suture failure).
9. Infectious diseases.
10. Psychiatric disorders: anorexia nervosa, severe depression.
11. Acute and chronic radiation injuries.

Contraindications for use

The same instructions indicate contraindications:

• intestinal obstruction;
• acute pancreatitis;
• severe forms of malabsorption.

Mixture selection principle

The data are given from the instructions of the Ministry of Health of the Russian Federation.

The choice of mixtures for adequate enteral nutrition should be based on data from clinical, instrumental and laboratory examination of patients, associated with the nature and severity of the disease and the degree of preservation of the functions of the gastrointestinal tract (GIT).

• With normal needs and the preservation of the functions of the gastrointestinal tract, standard nutrient mixtures are prescribed.
• With increased protein and energy requirements or fluid restriction, high-calorie nutrient mixtures are prescribed.
• Pregnant and breastfeeding women should be given nutritional formulas designed for this group.
• In critical and immunodeficiency states, nutritional mixtures with a high content of biologically active protein, enriched with trace elements, glutamine, arginine, omega-3 fatty acids, are prescribed.
• Patients with diabetes mellitus type I and II are assigned nutritional mixtures with a reduced content of fats and carbohydrates, containing dietary fiber.
• In case of impaired lung function, nutrient mixtures with a high content of fat and a low content of carbohydrates are prescribed.
• In case of impaired renal function, nutrient mixtures containing highly biologically valuable protein and amino acids are prescribed.
• In case of liver dysfunction, nutrient mixtures with a low content of aromatic amino acids and a high content of branched-chain amino acids are prescribed.
• With partially impaired functions of the gastrointestinal tract, nutrient mixtures based on oligopeptides are prescribed.

Nutrition rules

When using such a nutrition system, a number of rules should be observed in order to avoid complications.

• Start taking the mixture with a small daily portion (250-500 ml per day). With good tolerance, slowly increase it.
• Food should be taken slowly, in small sips through a tube.
• In case of food intolerance, attention should be paid to the presence of these types of elements in the mixture (eg lactose, gluten).
• With a restrictive diet, pay attention to a balanced diet.
• Additional fluid intake is required.
• The prepared mixture should not be stored for more than 24 hours. Store in the refrigerator, then reheat before use.
• In case of impaired absorption of fats, fat-free mixtures or mixtures with easily digestible fats should be taken.
• In severe malabsorption, a low molecular weight diet is recommended.
• If, nevertheless, intolerance manifests itself (increased diarrhea, nausea and vomiting), then the amount of food taken should be reduced and the intervals between meals should be increased. It may also be useful to replace a high molecular weight mixture with a low molecular weight mixture.

How are blends used?

Mixtures are diluted with boiled water and used for nutrition inside as the only source of nutrition (for seriously ill patients during a sharp exacerbation, more often with Crohn's disease) or as an additional source of nutrition along with the use of or 4c, depending on the functional state of the intestine, for patients with underweight, anemia, hypoproteinemia.

Depending on the duration of the course of enteral nutrition and the preservation of the functional state of various parts of the gastrointestinal tract, the following routes of administration of nutrient mixtures are distinguished:

• The use of nutrient mixtures in the form of drinks through a tube in small sips;
• Probe nutrition using nasogastric, nasoduodenal, nasojejunal and dual-channel probes (for aspiration of gastrointestinal contents and intra-intestinal administration of nutrient mixtures, mainly for surgical patients).
• By imposing a stoma: gastro-, duodeno-, jejuno-, iliostomy. Stomas can be placed surgically or endoscopically.

When some mixtures (cosylate, terapine) are ingested, diarrhea may worsen due to the occurrence of hyperosmolarity of the intestinal contents after the mixture has been consumed. The introduction through the tube is usually well tolerated, since the mixture enters the intestine evenly, in small portions. The following mixtures are most commonly used: isocal, cosylate, terapin, ensur, alferek, etc.

When is parenteral nutrition prescribed?

In especially severe cases, for example, with extensive stenosis, fistulas, it is necessary to completely exclude the intestines from the digestion process. In these cases, the mixture is administered by infusion into a vein. In this case, inflammation in the gastrointestinal tract quickly subsides, as it is without load.

In addition, this therapy is prescribed to maintain the balance of nutrients in patients with severe malabsorption (eg, after extensive resection of the small intestine) and inflammatory diseases in cases of very poor general condition, anorexia, with repeated vomiting.

However, with prolonged parenteral (intravenous) nutrition, there is always a change in the mucous membrane of the small intestine (the villi atrophy). Therefore, before resorting to parenteral nutrition, the possibility of enteral nutrition should be explored.

After exiting parenteral nutrition, the patient should begin to take small amounts of liquid mixtures to begin to restore the intestinal mucosa.

Types of parenteral nutrition

• Incomplete (partial) parenteral nutrition.
• Complete (total) parenteral nutrition provides the entire volume of the body's daily need for plastic and energy substrates, as well as maintaining the required level of metabolic processes.

Incomplete (partial) parenteral nutrition

This treatment is auxiliary and is aimed at replenishing those ingredients that are not supplied or absorbed by the enteral route. In addition, it is used as an additional if it is used in combination with the introduction of nutrients through a tube or orally.

Preparations for parenteral nutrition

There is a fairly wide range of drugs for parenteral nutrition.
For the introduction of nitrogen into the body, the following solutions of amino acids are available:

Solutions of amino acids without essential additives:

• aminosteril II (the concentration of amino acids in it is high, but it is a hypertonic solution, therefore it can cause thrombophlebitis);
• aminosteril III (in it the concentration of amino acids is much lower, but it does not lead to thrombophlebitis, as it is an isotonic solution);
• vamin-9, vamin-14, vamin-18, intrafusil, polyamine.

Solutions of amino acids combined:

• solutions of amino acids and ions: vamine-N, infezol-40, aminosteril KE 10%;
• solutions of amino acids, carbohydrates and ions: aminoplasmal 10%, vamine-glucose;
• solutions of amino acids with ions and vitamins: aminosteril L 600, L 800, aminosteril KE forte.

To introduce fats and ensure energy balance, there are fat emulsions: intralipid 10%, 20%, 30%, lipovenosis 10%, 20%, lipofundin MCT / LST.

There are also additives to preparations for parenteral nutrition:

• supplements with trace elements: addamel;
• supplements with vitamins: Vitalipid adult, Soluvite.

The composition of diets for parenteral nutrition also includes 5% glucose solution as a source of carbohydrates, vitamins, salts of potassium, calcium, magnesium and sodium. The need for nutrients is calculated depending on body weight according to the formula for a balanced diet.

Enteral and parenteral nutrition - which is better?

Advantages of enteral nutrition over parenteral nutrition:

• natural form of nutrition;
• cheaper;
• fewer complications;
• it is easier to return to regular products, as there is no atrophy of the villi.

artificial nutrition is today one of the basic types of treatment of patients in a hospital. There is practically no area of ​​medicine in which it would not be used. The most relevant is the use of artificial nutrition (or artificial nutritional support) for surgical, gastroenterological, oncological, nephrological and geriatric patients.

Nutritional Support- a complex of therapeutic measures aimed at identifying and correcting violations of the nutritional status of the body using the methods of nutritional therapy (enteral and parenteral nutrition). It is the process of providing the body with food substances (nutrients) through methods other than regular food intake.

“The failure of the doctor to provide food for the patient should be regarded as a decision to starve him to death. A decision for which in most cases it would be difficult to find an excuse," wrote Arvid Vretlind.

Timely and adequate nutritional support can significantly reduce the incidence of infectious complications and mortality in patients, improve the quality of life of patients and speed up their rehabilitation.

Artificial nutritional support can be complete, when all (or most) of the patient's nutritional needs are provided artificially, or partial, if the introduction of nutrients by enteral and parenteral routes is additional to conventional (oral) nutrition.

Indications for artificial nutritional support are diverse. In general, they can be described as any disease in which the patient's need for nutrients cannot be provided naturally. Usually these are diseases of the gastrointestinal tract, which do not allow the patient to eat adequately. Also, artificial nutrition may be necessary for patients with metabolic problems - severe hypermetabolism and catabolism, high loss of nutrients.

The rule "7 days or weight loss by 7%" is widely known. It means that artificial nutrition must be carried out in cases where the patient cannot eat naturally for 7 days or more, or if the patient has lost more than 7% of the recommended body weight.

Evaluation of the effectiveness of nutritional support includes the following indicators: dynamics of nutritional status parameters; state of nitrogen balance; the course of the underlying disease, the condition of the surgical wound; the general dynamics of the patient's condition, the severity and course of organ dysfunction.

There are two main forms of artificial nutritional support: enteral (tube) and parenteral (intravascular) nutrition.

• Features of human metabolism during fasting

  The primary reaction of the body in response to the cessation of the supply of nutrients from the outside is the use of glycogen and glycogen depots as an energy source (glycogenolysis). However, the stock of glycogen in the body is usually small and depleted during the first two to three days. In the future, the structural proteins of the body (gluconeogenesis) become the easiest and most accessible source of energy. In the process of gluconeogenesis, glucose-dependent tissues produce ketone bodies, which, by feedback reaction, slow down the basal metabolism and begin the oxidation of lipid reserves as an energy source. Gradually, the body switches to a protein-sparing mode of functioning, and gluconeogenesis resumes only when fat reserves are completely depleted. So, if in the first days of fasting, protein losses are 10-12 g per day, then in the fourth week - only 3-4 g in the absence of pronounced external stress.

  In critically ill patients, there is a powerful release of stress hormones - catecholamines, glucagon, which have a pronounced catabolic effect. At the same time, the production or response to anabolic hormones such as somatotropic hormone and insulin is blocked. As is often the case in critical conditions, the adaptive reaction, aimed at destroying proteins and providing the body with substrates for building new tissues and healing wounds, gets out of control and becomes purely destructive. Due to catecholaminemia, the body's transition to using fat as an energy source slows down. In this case (with severe fever, polytrauma, burns), up to 300 g of structural protein per day can be burned. This condition is called autocannibalism. Energy costs increase by 50-150%. For some time, the body can maintain its needs for amino acids and energy, but protein reserves are limited and the loss of 3-4 kg of structural protein is considered irreversible.

  The fundamental difference between physiological adaptation to starvation and adaptive reactions in terminal states is that in the first case, an adaptive decrease in energy demand is noted, and in the second case, energy consumption increases significantly. Therefore, in post-aggressive states, a negative nitrogen balance should be avoided, since protein depletion ultimately leads to death, which occurs when more than 30% of the total body nitrogen is lost.

  • Gastrointestinal tract during fasting and in critical condition

    In critical conditions of the body, conditions often arise in which adequate perfusion and oxygenation of the gastrointestinal tract is impaired. This leads to damage to the cells of the intestinal epithelium with a violation of the barrier function. Violations are aggravated if there are no nutrients in the lumen of the gastrointestinal tract for a long time (during starvation), since the cells of the mucosa receive food to a large extent directly from the chyme.

    An important factor damaging the digestive tract is any centralization of blood circulation. With the centralization of blood circulation, there is a decrease in the perfusion of the intestine and parenchymal organs. In critical conditions, this is aggravated by the frequent use of adrenomimetic drugs to maintain systemic hemodynamics. In time, the restoration of normal intestinal perfusion lags behind the restoration of normal perfusion of vital organs. The absence of chyme in the intestinal lumen impairs the supply of antioxidants and their precursors to enterocytes and exacerbates reperfusion injury. The liver, due to autoregulatory mechanisms, suffers somewhat less from a decrease in blood flow, but still its perfusion decreases.

    During starvation, microbial translocation develops, that is, the penetration of microorganisms from the lumen of the gastrointestinal tract through the mucous barrier into the blood or lymph flow. Escherihia coli, Enterococcus, and bacteria of the genus Candida are mainly involved in translocation. Microbial translocation is always present in certain amounts. Bacteria penetrating the submucosal layer are captured by macrophages and transported to the systemic lymph nodes. When they enter the bloodstream, they are captured and destroyed by the Kupffer cells of the liver. A stable balance is disturbed with uncontrolled growth of the intestinal microflora and a change in its normal composition (i.e. with the development of dysbacteriosis), impaired mucosal permeability, and impaired local intestinal immunity. It has been proven that microbial translocation occurs in critically ill patients. It is exacerbated by the presence of risk factors (burns and severe trauma, broad-spectrum systemic antibiotics, pancreatitis, hemorrhagic shock, reperfusion injury, exclusion of solid food, etc.) and is often the cause of infectious lesions in critically ill patients. In the United States, 10% of hospitalized patients develop a nosocomital infection. That's 2 million people, 580,000 deaths, and about $4.5 billion in treatment costs.

    Violations of the intestinal barrier function, expressed in mucosal atrophy and impaired permeability, develop quite early in critically ill patients and are already expressed on the 4th day of fasting. Many studies have shown the beneficial effect of early enteral nutrition (first 6 hours from admission) to prevent mucosal atrophy.

    In the absence of enteral nutrition, not only atrophy of the intestinal mucosa occurs, but also atrophy of the so-called gut-associated lymphoid tissue (GALT). These are Peyer's patches, mesenteric lymph nodes, epithelial and basement membrane lymphocytes. Maintaining normal nutrition through the intestines helps to maintain the immunity of the whole organism in a normal state.

• Principles of Nutritional Support

  One of the founders of the doctrine of artificial nutrition, Arvid Vretlind (A. Wretlind), formulated the principles of nutritional support:

  • Timeliness.

    Artificial nutrition should be started as early as possible, even before the development of nutritional disorders. It is impossible to wait for the development of protein-energy malnutrition, since cachexia is much easier to prevent than to treat.

  • Optimality.

    Artificial nutrition should be carried out until the nutritional status is stabilized.

  • Adequacy.

    Nutrition should cover the energy needs of the body and be balanced in terms of nutrient composition and meet the patient's needs for them.

• Enteral nutrition

  Enteral nutrition (EN) is a type of nutritional therapy in which nutrients are administered orally or through a gastric (intestinal) tube.

  Enteral nutrition refers to the types of artificial nutrition and, therefore, is not carried out through natural routes. For enteral nutrition, one or another access is required, as well as special devices for the introduction of nutrient mixtures.

  Some authors refer to enteral nutrition only methods that bypass the oral cavity. Others include oral nutrition with mixtures other than regular food. In this case, there are two main options: tube feeding - the introduction of enteral mixtures into a tube or stoma, and "sipping" (sipping, sip feeding) - oral intake of a special mixture for enteral nutrition in small sips (usually through a tube).

  • Benefits of Enteral Nutrition

    Enteral nutrition has several advantages over parenteral nutrition:

    • Enteral nutrition is more physiological.
    • Enteral nutrition is more economical.
    • Enteral nutrition practically does not cause life-threatening complications, does not require compliance with strict sterility conditions.
    • Enteral nutrition allows you to provide the body with the necessary substrates to a greater extent.
    • Enteral nutrition prevents the development of atrophic processes in the gastrointestinal tract.
  • Indications for enteral nutrition

    Indications for EN are almost all situations where it is impossible for a patient with a functioning gastrointestinal tract to meet the protein and energy needs in the usual, oral way.

    The global trend is the use of enteral nutrition in all cases where it is possible, if only because its cost is much lower than parenteral nutrition, and its efficiency is higher.

    For the first time, indications for enteral nutrition were clearly formulated by A. Wretlind, A. Shenkin (1980):

    • Enteral nutrition is indicated when the patient cannot eat food (lack of consciousness, swallowing disorders, etc.).
    • Enteral nutrition is indicated when the patient should not eat food (acute pancreatitis, gastrointestinal bleeding, etc.).
    • Enteral nutrition is indicated when the patient does not want to eat food (anorexia nervosa, infections, etc.).
    • Enteral nutrition is indicated when normal nutrition is not adequate to the needs (injuries, burns, catabolism).

    According to the "Instructions for the organization of enteral nutrition ..." The Ministry of Health of the Russian Federation distinguishes the following nosological indications for the use of enteral nutrition:

    • Protein-energy malnutrition when it is impossible to provide adequate intake of nutrients through the natural oral route.
    • Neoplasms, especially localized in the head, neck and stomach.
    • Disorders of the central nervous system: coma, cerebrovascular stroke or Parkinson's disease, as a result of which nutritional status disorders develop.
    • Radiation and chemotherapy in oncological diseases.
    • Diseases of the gastrointestinal tract: Crohn's disease, malabsorption syndrome, short bowel syndrome, chronic pancreatitis, ulcerative colitis, diseases of the liver and biliary tract.
    • Nutrition in the pre- and early postoperative periods.
    • Trauma, burns, acute poisoning.
    • Complications of the postoperative period (fistulas of the gastrointestinal tract, sepsis, anastomotic suture failure).
    • Infectious diseases.
    • Psychiatric disorders: anorexia nervosa, severe depression.
    • Acute and chronic radiation injuries.
  • Contraindications for enteral nutrition

    Enteral nutrition is a technique that is being intensively researched and used in an increasingly diverse group of patients. There is a breakdown of stereotypes about mandatory fasting in patients after operations on the gastrointestinal tract, in patients immediately after recovery from a state of shock, and even in patients with pancreatitis. As a result, there is no consensus on absolute contraindications for enteral nutrition.

    Absolute contraindications to enteral nutrition:

    • Clinically pronounced shock.
    • intestinal ischemia.
    • Complete intestinal obstruction (ileus).
    • Refusal of the patient or his guardian from the conduct of enteral nutrition.
    • Ongoing gastrointestinal bleeding.

    Relative contraindications to enteral nutrition:

    • Partial bowel obstruction.
    • Severe uncontrollable diarrhea.
    • External enteric fistulas with a discharge of more than 500 ml / day.
    • Acute pancreatitis and pancreatic cyst. However, there are indications that enteral nutrition is possible even in patients with acute pancreatitis in the distal position of the probe and the use of elemental diets, although there is no consensus on this issue.
    • A relative contraindication is also the presence of large residual volumes of food (fecal) masses in the intestines (in fact, intestinal paresis).
  • General recommendations for enteral nutrition
    • Enteral nutrition should be given as early as possible. Conduct nutrition through a nasogastric tube, if there are no contraindications to this.
    • Enteral nutrition should be started at a rate of 30 ml/hour.
    • It is necessary to determine the residual volume as 3 ml/kg.
    • It is necessary to aspirate the contents of the probe every 4 hours and if the residual volume does not exceed 3 ml / hour, then gradually increase the feeding rate until the calculated one is reached (25-35 kcal / kg / day).
    • In cases where the residual volume exceeds 3 ml / kg, then treatment with prokinetics should be prescribed.
    • If after 24-48 hours, due to high residual volumes, it is still not possible to adequately feed the patient, then a probe should be inserted into the ileum using a blind method (endoscopically or under X-ray control).
    • The nursing nurse who provides enteral nutrition should be taught that if she cannot do it properly, then this means that she cannot provide proper care to the patient at all.
  • When to start enteral nutrition

    The literature mentions the benefits of “early” parenteral nutrition. Data are given that in patients with multiple injuries immediately after stabilization of the condition, in the first 6 hours from admission, enteral nutrition was started. Compared with the control group, when nutrition began after 24 hours from admission, there was a less pronounced violation of the permeability of the intestinal wall and less pronounced multiple organ disorders.

    In many intensive care centers, the following tactic has been adopted: enteral nutrition should begin as early as possible - not only in order to immediately achieve replenishment of the patient's energy costs, but in order to prevent changes in the intestine, which can be achieved by enteral nutrition with relatively small volumes of food introduced .

    Theoretical substantiation of early enteral nutrition.

    No enteral nutrition leads to:
    Mucosal atrophy.	Proven in animal experiments.
    Excessive colonization of the small intestine.	Enteral nutrition prevents this in the experiment.
    Translocation of bacteria and endotoxins to the portal circulation.	People have a violation of the permeability of the mucosa during burns, trauma and in critical conditions.

  • Enteral feeding regimens

    The choice of diet is determined by the condition of the patient, the underlying and concomitant pathology and the capabilities of the medical institution. The choice of method, volume and speed of EN are determined individually for each patient.

    There are the following modes of enteral nutrition:

    • Feed at a constant rate.

      Nutrition through a gastric tube begins with isotonic mixtures at a rate of 40-60 ml / h. If well tolerated, the feeding rate can be increased by 25 ml/h every 8–12 hours until the desired rate is reached. When feeding through a jejunostomy tube, the initial rate of administration of the mixture should be 20–30 ml/h, especially in the immediate postoperative period.

      With nausea, vomiting, convulsions or diarrhea, it is required to reduce the rate of administration or the concentration of the solution. At the same time, simultaneous changes in the feed rate and the concentration of the nutrient mixture should be avoided.

    • Cyclic food.

      Continuous drip introduction is gradually "squeezed" to a 10-12-hour night period. Such nutrition, convenient for the patient, can be carried out through the gastrostomy.

    • Periodic or session nutrition.

      Nutrition sessions for 4-6 hours are carried out only in the absence of a history of diarrhea, malabsorption syndrome and operations on the gastrointestinal tract.

    • Bolus nutrition.

      It mimics a normal meal, so it provides a more natural functioning of the gastrointestinal tract. It is carried out only with transgastric accesses. The mixture is administered by drip or syringe at a rate of not more than 240 ml for 30 minutes 3-5 times a day. The initial bolus should not exceed 100 ml. With good tolerance, the injected volume is increased daily by 50 ml. Bolus feeding is more likely to cause diarrhea.

    • Usually, if the patient has not received food for several days, a constant drip of mixtures is preferable to intermittent. Continuous 24-hour nutrition is best used in cases where there are doubts about the preservation of the functions of digestion and absorption.
  • Enteral nutrition mixtures

    The choice of a mixture for enteral nutrition depends on many factors: the disease and the general condition of the patient, the presence of disorders of the patient's digestive tract, the required regimen of enteral nutrition.

    • General requirements for enteral mixtures.
      • The enteral mixture must have sufficient energy density (at least 1 kcal/ml).
      • The enteral mixture should not contain lactose and gluten.
      • The enteral mixture should have a low osmolarity (no more than 300–340 mosm/l).
      • The enteral mixture should have a low viscosity.
      • The enteral mixture should not cause excessive stimulation of intestinal motility.
      • The enteral mixture should contain sufficient data on the composition and manufacturer of the nutrient mixture, as well as indications of the presence of a genetic modification of nutrients (proteins).

    None of the mixtures for complete EN contains enough free water to meet the patient's daily fluid requirement. The daily fluid requirement is usually estimated as 1 ml per 1 kcal. Most mixtures with an energy value of 1 kcal / ml contain approximately 75% of the required water. Therefore, in the absence of indications for fluid restriction, the amount of additional water consumed by the patient should be approximately 25% of the total diet.

    At present, mixtures prepared from natural products or recommended for infant nutrition are not used for enteral nutrition due to their imbalance and inadequacy to the needs of adult patients.

  • Complications of enteral nutrition

    Prevention of complications is strict adherence to the rules of enteral nutrition.

    The high incidence of complications of enteral nutrition is one of the main limiting factors for its widespread use in critically ill patients. The presence of complications leads to frequent cessation of enteral nutrition. There are quite objective reasons for such a high frequency of complications of enteral nutrition.

    • Enteral nutrition is carried out in a severe category of patients, with damage to all organs and systems of the body, including the gastrointestinal tract.
    • Enteral nutrition is necessary only for those patients who already have intolerance to natural nutrition for various reasons.
    • Enteral nutrition is not natural nutrition, but artificial, specially prepared mixtures.
    • Classification of complications of enteral nutrition

      There are the following types of complications of enteral nutrition:

      • Infectious complications (aspiration pneumonia, sinusitis, otitis, infection of wounds in gastoenterostomies).
      • Gastrointestinal complications (diarrhea, constipation, bloating, regurgitation).
      • Metabolic complications (hyperglycemia, metabolic alkalosis, hypokalemia, hypophosphatemia).

      This classification does not include complications associated with the enteral feeding technique - self-extraction, migration and blockage of feeding tubes and tubes. In addition, a gastrointestinal complication such as regurgitation may coincide with an infectious complication such as aspiration pneumonia. starting with the most frequent and significant.

      The literature indicates the frequency of various complications. The wide spread of data is explained by the fact that there are no common diagnostic criteria for determining a particular complication and there is no single protocol for managing complications.

      • High residual volumes - 25% -39%.
      • Constipation - 15.7%. With long-term enteral nutrition, the frequency of constipation can increase up to 59%.
      • Diarrhea - 14.7% -21% (from 2 to 68%).
      • Bloating - 13.2% -18.6%.
      • Vomiting - 12.2% -17.8%.
      • Regurgitation - 5.5%.
      • Aspiration pneumonia - 2%. According to various authors, the frequency of aspiration pneumonia is indicated from 1 to 70 percent.
  • About Sterility in Enteral Nutrition

    One of the advantages of enteral nutrition over parenteral nutrition is that it is not necessarily sterile. However, it must be remembered that, on the one hand, enteral nutrition mixtures are an ideal environment for the reproduction of microorganisms and, on the other hand, there are all conditions for bacterial aggression in intensive care units. The danger is both the possibility of infection of the patient with microorganisms from the nutrient mixture, and poisoning by the resulting endotoxin. It must be taken into account that enteral nutrition is always carried out bypassing the bactericidal barrier of the oropharynx and, as a rule, enteral mixtures are not treated with gastric juice, which has pronounced bactericidal properties. Antibacterial therapy, immunosuppression, concomitant infectious complications, etc. are called other factors associated with the development of infection.

    The usual recommendations to prevent bacterial contamination are: use no more than 500 ml volumes of locally prepared formula. And use them for no more than 8 hours (for sterile factory solutions - 24 hours). In practice, there are no experimentally substantiated recommendations in the literature on the frequency of replacement of probes, bags, droppers. It seems reasonable that for droppers and bags this should be at least once every 24 hours.

• parenteral nutrition

  Parenteral nutrition (PN) is a special type of replacement therapy in which nutrients are introduced into the body to replenish energy, plastic costs and maintain a normal level of metabolic processes, bypassing the gastrointestinal tract directly into the internal environment of the body (usually into the vascular bed) .

  The essence of parenteral nutrition is to provide the body with all the substrates necessary for normal life, involved in the regulation of protein, carbohydrate, fat, water-electrolyte, vitamin metabolism and acid-base balance.

  • Classification of parenteral nutrition
    • Complete (total) parenteral nutrition.

      Complete (total) parenteral nutrition provides the entire volume of the body's daily need for plastic and energy substrates, as well as maintaining the required level of metabolic processes.

    • Incomplete (partial) parenteral nutrition.

      Incomplete (partial) parenteral nutrition is auxiliary and is aimed at selective replenishment of the deficiency of those ingredients, the intake or assimilation of which is not provided by the enteral route. Incomplete parenteral nutrition is considered supplementary nutrition if it is used in combination with tube or oral nutrition.

    • Mixed artificial nutrition.

      Mixed artificial nutrition is a combination of enteral and parenteral nutrition in cases where neither of them is predominant.

  • The main tasks of parenteral nutrition
    • Restoration and maintenance of water-electrolyte and acid-base balance.
    • Providing the body with energy and plastic substrates.
    • Providing the body with all the necessary vitamins, macro- and microelements.
  • Concepts of parenteral nutrition

    Two main concepts of PP have been developed.

    1. The "American concept" - the hyperalimentation system according to S. Dudrick (1966) - implies the separate introduction of solutions of carbohydrates with electrolytes and nitrogen sources.
    2. The "European concept" created by A. Wretlind (1957) implies the separate introduction of plastic, carbohydrate and fat substrates. Its later version is the "three in one" concept (Solasson C, Joyeux H.; 1974), according to which all the necessary nutritional components (amino acids, monosaccharides, fat emulsions, electrolytes and vitamins) are mixed before administration in a single container under aseptic conditions.

       In recent years, all-in-one parenteral nutrition has been introduced in many countries, using 3 liter containers to mix all the ingredients in one plastic bag. If it is not possible to mix "three in one" solutions, the infusion of plastic and energy substrates should be carried out in parallel (preferably through a V-shaped adapter).

       In recent years, ready-made mixtures of amino acids and fat emulsions have been produced. The advantages of this method are minimized manipulations with containers containing nutrients, their infection is reduced, the risk of hypoglycemia and hyperosmolar non-ketone coma is reduced. Disadvantages: sticking of fat particles and formation of large globules that can be dangerous for the patient, the problem of catheter occlusion has not been solved, it is not known how long this mixture can be safely refrigerated.

  • Basic principles of parenteral nutrition
    • Timely start of parenteral nutrition.
    • Optimal timing of parenteral nutrition (until normal trophic status is restored).
    • Adequacy (balance) of parenteral nutrition in terms of the amount of nutrients introduced and the degree of their assimilation.
  • Rules for parenteral nutrition
    • Nutrients should be introduced in a form adequate to the metabolic needs of the cells, that is, similar to the intake of nutrients into the bloodstream after passing through the enteric barrier. Accordingly: proteins in the form of amino acids, fats - fat emulsions, carbohydrates - monosaccharides.
    • Strict adherence to the appropriate rate of introduction of nutrient substrates is necessary.
    • Plastic and energy substrates must be introduced simultaneously. Be sure to use all the essential nutrients.
    • Infusion of high-osmolar solutions (especially those exceeding 900 mosmol/l) should be carried out only in the central veins.
    • PN infusion sets are changed every 24 hours.
    • When carrying out a complete PP, the inclusion of glucose concentrates in the composition of the mixture is mandatory.
    • The fluid requirement for a stable patient is 1 ml/kcal or 30 ml/kg of body weight. In pathological conditions, the need for water increases.
  • Indications for parenteral nutrition

    When carrying out parenteral nutrition, it is important to take into account that in the conditions of cessation or restriction of the supply of nutrients by exogenous means, the most important adaptive mechanism comes into play: the consumption of mobile reserves of carbohydrates, fats of the body and the intensive breakdown of protein to amino acids with their subsequent transformation into carbohydrates. Such metabolic activity, being initially expedient, designed to ensure vital activity, subsequently has a very negative effect on the course of all life processes. Therefore, it is advisable to cover the needs of the body not due to the decay of its own tissues, but due to the exogenous supply of nutrients.

    The main objective criterion for the use of parenteral nutrition is a pronounced negative nitrogen balance, which cannot be corrected by the enteral route. The average daily loss of nitrogen in intensive care patients ranges from 15 to 32 g, which corresponds to the loss of 94-200 g of tissue protein or 375-800 g of muscle tissue.

    The main indications for PP can be divided into several groups:

    • Impossibility of oral or enteral food intake for at least 7 days in a stable patient, or for a shorter period in a malnourished patient (this group of indications is usually associated with disorders of the gastrointestinal tract).
    • Severe hypermetabolism or significant loss of protein when enteral nutrition alone fails to cope with nutrient deficiencies (burn disease is a classic example).
    • The need for a temporary exclusion of intestinal digestion "intestinal rest mode" (for example, with ulcerative colitis).
    • Indications for total parenteral nutrition

      Total parenteral nutrition is indicated in all cases when it is impossible to take food naturally or through a tube, which is accompanied by an increase in catabolic and inhibition of anabolic processes, as well as a negative nitrogen balance:

      • In the preoperative period in patients with symptoms of complete or partial starvation in diseases of the gastrointestinal tract in cases of functional or organic damage to it with impaired digestion and resorption.
      • In the postoperative period after extensive operations on the abdominal organs or its complicated course (anastomotic failure, fistulas, peritonitis, sepsis).
      • In the post-traumatic period (severe burns, multiple injuries).
      • With increased protein breakdown or violation of its synthesis (hyperthermia, insufficiency of the liver, kidneys, etc.).
      • Resuscitation patients, when the patient does not regain consciousness for a long time or the activity of the gastrointestinal tract is sharply impaired (CNS lesions, tetanus, acute poisoning, coma, etc.).
      • In infectious diseases (cholera, dysentery).
      • With neuropsychiatric diseases in cases of anorexia, vomiting, refusal of food.
  • Contraindications for parenteral nutrition
    • Absolute contraindications for PP
      • Period of shock, hypovolemia, electrolyte disturbances.
      • Possibility of adequate enteral and oral nutrition.
      • Allergic reactions to components of parenteral nutrition.
      • Refusal of the patient (or his guardian).
      • Cases in which PN does not improve the prognosis of the disease.

      In some of the listed situations, PP elements can be used in the course of complex intensive care of patients.

    • Contraindications to the use of certain drugs for parenteral nutrition

      Contraindications to the use of certain drugs for parenteral nutrition determine pathological changes in the body due to underlying and concomitant diseases.

      • In hepatic or renal insufficiency, amino acid mixtures and fat emulsions are contraindicated.
      • With hyperlipidemia, lipoid nephrosis, signs of post-traumatic fat embolism, acute myocardial infarction, cerebral edema, diabetes mellitus, in the first 5-6 days of the post-resuscitation period and in violation of the coagulating properties of blood, fat emulsions are contraindicated.
      • Caution must be exercised in patients with allergic diseases.
  • Provision of parenteral nutrition
    • Infusion technology

      The main method of parenteral nutrition is the introduction of energy, plastic substrates and other ingredients into the vascular bed: into the peripheral veins; into the central veins; into the recanalized umbilical vein; through shunts; intra-arterially.

      When conducting parenteral nutrition, infusion pumps, electronic drop regulators are used. The infusion should be carried out within 24 hours at a certain rate, but not more than 30-40 drops per minute. At this rate of administration, there is no overload of enzyme systems with nitrogen-containing substances.

    • Access

      The following access options are currently in use:

      • Through a peripheral vein (using a cannula or catheter), it is usually used when initializing parenteral nutrition for up to 1 day or with additional PN.
      • Through a central vein using temporary central catheters. Among the central veins, preference is given to the subclavian vein. The internal jugular and femoral veins are less commonly used.
      • Through a central vein using indwelling central catheters.
      • Through alternative vascular accesses and extravascular accesses (for example, the peritoneal cavity).
  • Parenteral nutrition regimens
    • Round-the-clock introduction of nutrient media.
    • Extended infusion (within 18-20 hours).
    • Cyclic mode (infusion for 8-12 hours).
  • Preparations for parenteral nutrition
    • Basic requirements for parenteral nutrition products

      Based on the principles of parenteral nutrition, parenteral nutrition products must meet several basic requirements:

      • To have a nutritional effect, that is, to have in its composition all the substances necessary for the body in sufficient quantities and in proper proportions with each other.
      • Replenish the body with fluid, as many conditions are accompanied by dehydration.
      • It is highly desirable that the agents used have a detoxifying and stimulating effect.
      • The replacement and anti-shock effect of the means used is desirable.
      • It is necessary to make sure that the means used are harmless.
      • An important component is ease of use.
    • Characteristics of parenteral nutrition products

      For the competent use of nutrient solutions for parenteral nutrition, it is necessary to evaluate some of their characteristics:

      • Osmolarity of solutions for parenteral nutrition.
      • Energy value of solutions.
      • Limits of maximum infusions - the pace or speed of infusion.
      • When planning parenteral nutrition, the necessary doses of energy substrates, minerals and vitamins are calculated based on their daily requirement and the level of energy consumption.
    • Components of parenteral nutrition

      The main components of parenteral nutrition are usually divided into two groups: energy donators (carbohydrate solutions - monosaccharides and alcohols and fat emulsions) and plastic material donators (amino acid solutions). Means for parenteral nutrition consist of the following components:

      • Carbohydrates and alcohols are the main sources of energy in parenteral nutrition.
      • Sorbitol (20%) and xylitol are used as additional energy sources with glucose and fat emulsions.
      • Fats are the most efficient energy substrate. They are administered in the form of fat emulsions.
      • Proteins - are the most important component for building tissues, blood, synthesis of proteohormones, enzymes.
      • Salt solutions: simple and complex, are introduced to normalize the water-electrolyte and acid-base balance.
      • Vitamins, trace elements, anabolic hormones are also included in the parenteral nutrition complex.
    Read more: Pharmacological group - Means for parenteral nutrition.
  • Assessment of the patient's condition if parenteral nutrition is required

    When conducting parenteral nutrition, it is necessary to take into account the individual characteristics of the patient, the nature of the disease, metabolism, as well as the energy needs of the body.

    • Evaluation of nutrition and control of the adequacy of parenteral nutrition.

      The aim is to determine the type and extent of malnutrition and the need for nutritional support.

      Nutritional status in recent years has been assessed based on the definition of trophic or trophological status, which is considered as an indicator of physical development and health. Trophic insufficiency is established on the basis of anamnesis, somatometric, laboratory and clinical and functional parameters.

      • Somatometric indicators are the most accessible and include the measurement of body weight, shoulder circumference, thickness of the skin-fat fold and the calculation of the body mass index.
      • Laboratory tests.

        Serum albumin. With its decrease below 35 g/l, the number of complications increases by 4 times, mortality by 6 times.

        Serum transferrin. Its decrease indicates the depletion of visceral protein (the norm is 2 g / l or more).

        Excretion of creatinine, urea, 3-methylhistidine (3-MG) in the urine. A decrease in creatinine and 3-MG excreted in the urine indicates a deficiency of muscle protein. The 3-MG / creatinine ratio reflects the direction of metabolic processes towards anabolism or catabolism and the effectiveness of parenteral nutrition in correcting protein deficiency (urinary excretion of 4.2 μM 3-MG corresponds to the breakdown of 1 g of muscle protein).

        Control of blood and urine glucose concentrations: The appearance of sugar in the urine and an increase in blood glucose concentrations of more than 2 g / l requires not so much an increase in the dose of insulin, but a decrease in the amount of glucose administered.

      • Clinical and functional indicators: decrease in tissue turgor, the presence of cracks, edema, etc.
  • Monitoring parenteral nutrition

    The parameters for monitoring homeostasis parameters during complete PN were determined in Amsterdam in 1981.

    Monitoring is carried out over the state of metabolism, the presence of infectious complications and nutritional efficiency. Indicators such as body temperature, pulse rate, blood pressure and respiratory rate are determined in patients daily. The determination of the main laboratory parameters in unstable patients is mainly carried out 1-3 times a day, with nutrition in the pre- and postoperative period 1-3 times a week, with prolonged PN - 1 time per week.

    Particular importance is attached to indicators characterizing the adequacy of nutrition - protein (urea nitrogen, serum albumin and prothrombin time), carbohydrate (

    Alternative - parenteral nutrition is used only when it is impossible to carry out enteral (intestinal fistulas with significant discharge, short bowel syndrome or malabsorption, intestinal obstruction, etc.).

    Parenteral nutrition is several times more expensive than enteral nutrition. When it is carried out, strict observance of sterility and the rate of introduction of ingredients is required, which is associated with certain technical difficulties. Parenteral nutrition gives a sufficient number of complications. There are indications that parenteral nutrition can depress one's own immunity.

    In any case, during complete parenteral nutrition, intestinal atrophy occurs - atrophy from inactivity. Atrophy of the mucosa leads to its ulceration, atrophy of the secreting glands leads to the subsequent occurrence of enzyme deficiency, bile stasis occurs, uncontrolled growth and changes in the composition of the intestinal microflora, atrophy of the lymphoid tissue associated with the intestine.

    Enteral nutrition is more physiological. It does not require sterilization. Enteral nutrition mixtures contain all the necessary components. The calculation of the need for enteral nutrition and the methodology for its implementation are much simpler than with parenteral nutrition. Enteral nutrition allows you to maintain the gastrointestinal tract in a normal physiological state and prevent many complications that occur in critically ill patients. Enteral nutrition leads to improved blood circulation in the intestine and promotes normal healing of anastomoses after intestinal surgery. Thus, whenever possible, the choice of nutritional support should lean towards enteral nutrition.