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During parenteral nutrition of patients, nutrients are administered. Features of parenteral nutrition

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

Of course, nutrition, as an integral component of critical care, can also cause harm due to various factors. This especially applies to the parenteral route of administration of nutrients.

Without a doubt, from a safety point of view, it is necessary to drink and eat through the mouth, since this is inherent in human physiology; therefore, if such a possibility exists, the introduction of fluids, electrolytes, macro- and micronutrients should be carried out naturally.

  • it maintains the structure of the intestinal villi;
  • stimulates the secretion of brush border enzymes, endopeptides, immunoglobulin A, bile acids;
  • preserves the integrity of the intestinal epithelium connections;
  • reduces the permeability of the intestinal epithelium;
  • prevents bacterial translocation.
  • intestinal starvation;
  • increased incidence of infectious complications;
  • metabolic complications;
  • immunological complications;
  • organ dysfunction.

Obvious problems encountered during 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 during TPN.

According to the latest recommendations of the European Society for Parenteral and Enteral Nutrition (ESPEN), of which Russia is also a member, “starvation or malnutrition of patients in the intensive care clinic increases the mortality rate (category C), accordingly, parenteral nutrition can be started in patients who are in the next Enteral nutrition cannot be started within 24 hours (category B), and in patients with nutritional deficiency who cannot receive adequate nutrition orally or enterally (category C).”

At the beginning of the 21st century. The topic of death from parenteral nutrition has been discussed in the literature for several years. The authors attributed problems such as gastrointestinal mucosal atrophy, bacterial overgrowth, bacterial translocation, atrophy of intestinal lymphoid tissue, decreased levels of immunoglobulin A in respiratory secretions, decreased immunity, as well as hepatic steatosis and liver failure to parenteral nutrition.

However, the dangers of parenteral nutrition in general are greatly exaggerated, and here's why. In contrast to experimental data obtained on animals, 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 a consequence of hypercaloric content and excess glucose, as well as imperfect parenteral nutrition technology.

It should be noted that comparison and, even more so, contrast between the parenteral and enteral routes 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 medical histories for the period 2005-2007. It turned out that patients receiving parenteral nutrition were more likely to die in all respects than patients receiving 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.

It also seems incorrect when talking about the dangers of parenteral nutrition to refer to studies that used the strategy of hyperalimentation, providing calories mainly from glucose, and parenteral nutrition drugs of “older” generations.

Thus, in 2006, a randomized controlled trial was conducted (n = 326), 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 lower 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 technologies for parenteral nutrition are being improved.

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

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

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

  1. Calorie safety: how many calories are safe?
  2. Ingredient safety: what is safe to feed?
  3. Volume safety: what volume of the mixture corresponds to the caloric content and composition?
  4. Osmotic and metabolic safety: what is a safe rate of administration?
  5. Which is safer: vials or all-in-one systems?
  6. Compatibility and stability issues for parenteral nutrition solutions: how to safely mix nutrients?
  7. What is the optimal glycemic level and is it necessary to administer insulin when using parenteral nutrition solutions?
  8. Infectious safety: how to reduce the number of infectious complications when using parenteral nutrition solutions?

Before considering all the questions posed 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 (safety of composition);
  • lack of fat (safety of the composition);
  • amino acid imbalance (excess methionine) (composition safety);
  • excess phytosterols (safety of the composition);
  • disruption of the circulation of bile acids during parenteral nutrition.

Calorie safety: isocaloric or hypocaloric nutrition?

One of the striking examples of the dangerous use of hypercaloric nutrition is the so-called refeeding syndrome (“refeeding syndrome”), which was described in released concentration camp prisoners with 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 caloric intake safety is: start low go slow, that is, you should start with an incomplete calculated caloric intake and gradually increase it to the calculated one over 2-3 days.

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

In a study by S. Dissanaike et al. It has been established that hypercaloric parenteral nutrition leads to a significant increase in the incidence of bloodstream infections, and the higher the caloric intake, the higher the percentage of complications. At the same time, if normal caloric intake is ensured (less than 25 kcal/kg), the frequency of bloodstream infections is low (less than 10%).

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

Paradoxically, total parenteral nutrition appears to be the most acceptable from the point of view of caloric safety: in comparison with the natural method of nutrition, enteral nutrition and various combinations (including combinations with parenteral nutrition), when using it, the frequency of “underfeeding” and “overfeeding” is minimal.

The greatest “underfeeding” was observed when patients were fed orally (up to 80% of patients received less than 80% of the basal metabolic rate), 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 basal metabolic rate).

Not only “underfeeding”, but also “overfeeding” poses a danger to the patient, therefore it is advisable to use strict calorie control, in the absence of calorie control - 20-30 kcal/kg/day (for obesity - based on ideal body weight), to ensure isocaloric regimen often requires the use of parenteral nutrition or a combination of parenteral and enteral nutrition.

Volume safety

Several well-designed studies have demonstrated that the choice of volume of fluid therapy during the treatment of shock and in the subsequent days of treatment significantly affects the prognosis. Insufficient infusion when treating shock and excess fluid in the following days lead to the worst outcome.

In terms of safety volume of parenteral nutrition, there are some points to remember:

  • The restrictive strategy of infusion therapy dictates the need to reduce the volume 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

In accordance with the 2009 ESPEN recommendations, the introduction of high-osmolar parenteral nutrition solutions intended to fully provide the body with nutrients requires the installation of a central venous access (category C); installation of 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!

Composition safety: glucose and glycemic control

Glucose is an essential macronutrient, and without it adequate nutrition is impossible. However, hyperglycemia, which often occurs in critically ill patients and, of course, is often observed with parenteral administration, is characterized by a number of negative effects, most of which have been studied in patients with diabetes: 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 during hyperglycemia.

It is important to remember the major metabolic consequences of hyperglycemia, which ultimately lead to complications and poor outcome. These consequences include protein catabolism, increased hepatic gluconeogenesis from amino acids from muscle breakdown, insulin resistance, and a decrease in the effect of insulin as a muscle anabolic.

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

  • during parenteral nutrition, blood glucose concentrations 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 should not exceed 0.5 g/kg/h;
  • commercial all-in-one systems have different amounts of glucose (different rates of utilization, different risks of hyperglycemia, liponeogenesis, and protein catabolism).

Composition safety: amino acids and protein

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

The balance of the amino acid solution assumes the presence of 19 amino acids, including all essential amino acids, with the essential/essential ratio being about 1, the essential/total nitrogen ratio being about 3, the leucine/isoleucine ratio being 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 recommendations, “if parenteral nutrition is indicated for an ICU patient, the amino acid solution should contain L-glutamine in such an amount that the patient receives 0.2-0.4 g/kg 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, positive nitrogen balance, and sufficient essential nutrients may also obviate the need for exogenous glutamine supplementation.

Composition safety: fat emulsions

Parenteral nutrition of patients in critical conditions is impossible without the use of fat emulsions. There are several reasons for this.

  • Firstly, fat emulsions are the only source of essential fatty acids and phospholipids, which serve as building materials for cell membranes, precursors of mediators and hormones.
  • Secondly, being a high-energy substrate, they allow you to avoid excess glucose, thus preventing the rise in glycemia and reducing the respiratory quotient (RQ).
  • Thirdly, certain classes of fatty acids (omega-3) are credited with a number of “healing” properties.

However, in patients in critical conditions (especially with sepsis), attention should be paid to the following metabolic features: an increase in lipid oxidation compared to patients after planned operations, in whom glucose oxidation predominates.

All this is reflected in the 2009 ESPEN recommendations: “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, and therefore often refuse to prescribe drugs of this class.

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

A pyrogenic reaction can occur when introducing emulsions of all generations in the event of a violation of the rate of administration or a disturbance in 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 administration of fat emulsions are followed, these and many other problems do not arise.

Some physicians believe that ketoacidosis occurs with medium-chain triglycerides (MCTs), but studies of acid-base status with MCT emulsions in all age groups, including premature infants, have found no change in acid-base status. An increase in ketone bodies in the blood 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 disposal from the vascular bed.

According to the 2009 ESPEN recommendations, “intravenous fat emulsions (MCT, LCT or mixtures of emulsions) can be prescribed at a dose of 0.7-1.5 g/kg over 12-24 hours”, that is, the rate of administration of the emulsion should not be 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 disadvantages, the primary role of LCT is to provide the body with essential fatty acids.

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

The main role of MCT is as an energy substrate. Isolated administration of MCT emulsions is impossible, since, 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 products (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 greater preference to emulsions of the 2nd (MCT/LCT) and 3rd (MCT/LCT/fish oil + olive oil) generations: “In critically ill patients, the administration 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 number of beneficial effects, it should be noted that isolated administration of omega-3 (without LCT, LCT/MCT or LCT/olive oil) is unsafe, since they are poorly hydrolyzed by lipoprotein lipase and, accordingly, may accumulate in the circulatory system.

Moreover, the combination of omega-3 and LCT emulsions is also unsafe due to the 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 lipoprotein hydrolysis, increases the rate of fatty acid utilization 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 the hydrolysis of lipoproteins when combined with LCT, and omega-3 fatty acids that have an immunomodulatory effect.

Safety of fat emulsions when mixed: stability issue

One of the fundamental points from the point of view of the safety of using 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 most strict pharmacopoeias in the world - American (USP), the average size of a fat globule in a solution for parenteral administration should not exceed 0.5 μm (1/10 of the diameter of the pulmonary capillary), and the proportion of large globules should be more than 5 μm (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 pulmonary capillaries, damage to the lung endothelium, pronounced leukocyte infiltration of lung tissue with the development of acute lung injury.

There are several factors that influence the destabilization of the fat emulsion. Firstly, 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.

In this case, the development time of an unstable fat emulsion depends on the qualitative composition of the emulsion. Thus, emulsions based on soybean oil (first generation - LCT emulsions) or a combination of soybean and safflower oils become unstable after 12 hours and after 24 hours 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 oil remain stable 30 hours after the start of the infusion!

Secondly, the stability of fat emulsions in glass bottles and all-in-one plastic bags can be fundamentally different. Thus, in a study by D. F. Driscoll et al. all declared 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 was above acceptable values ​​when they were based on soybean oil, but remained normal when they contained a combination of MCT/LCT (coconut and soybean oils).

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

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

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

For 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 microelements) to the amino acid solution;
  2. then add glucose;
  3. then add the 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. Thus, P. Wischmeyer et al. their study compared the use of all-in-one systems with the bottle-based parenteral nutrition system in 31,129 patients in 182 hospitals: the incidence of bloodstream infections with the bottle-based method was 8.1% higher than with the all-in-one system. 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 targeted nutrition using an individual modular scheme.

Conclusion

The problem of the 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 problem should address caloric intake, qualitative and quantitative composition of parenteral nutrition, effects on metabolism, storage rules, mixing and infectious safety.

The use of modern all-in-one systems, provided that the rules for storing, mixing and administering parenteral nutrition and infection control drugs are followed, is safe for the patient.

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


Artificial nutrition (enteral or parenteral) is indicated for patients who have not received food for 7–10 days, as well as in cases where independent nutrition is not enough to maintain normal nutritional status.

Parenteral nutrition is used when natural nutrition is impossible or insufficient.

The purpose of parenteral nutrition is to provide the body with plastic materials, energy resources, electrolytes, microelements and vitamins.

The need for parenteral nutrition is associated with the catabolic orientation of metabolism in traumatic injuries, diseases of internal organs, severe infectious processes and in the postoperative period. The severity of the catabolic reaction is directly proportional to the severity of the lesion or disease.

With any injury, hemodynamic and respiratory disorders may occur, leading to hypoxia, disruption of water and electrolyte balance, acid-base status, hemostasis and rheological properties of blood. At the same time, during stress, the basal metabolism is stimulated through the pituitary gland, adrenal cortex, and thyroid gland, energy consumption increases, and the breakdown of carbohydrates and proteins increases.

Glucose reserves in the form of glycogen (in muscles and liver) during fasting are quickly depleted (after 12–14 hours), then their own protein is broken down into amino acids, which are converted into glucose in the liver. This process (gluconeogenesis) is uneconomical (56 g of glucose is produced from 100 g of protein) and leads to rapid protein loss.

Large protein losses negatively affect reparative processes, immunity and create conditions for the development of complications. Malnutrition in surgical patients leads to an increase in postoperative complications by 6 times, and mortality by 11 times (G.P. Buzby and J.L. Mullen, 1980).

Indications for parenteral nutrition can be conditionally combined into 3 groups: primary therapy, in which the influence of nutrition on the disease that caused the nutritional imbalance is assumed; maintenance therapy, which provides nutritional support but does not influence the cause of the disease; indications that are under study (J.E. Fischer, 1997).

Primary therapy:

3. Short bowel syndrome (After extensive resection of the small intestine, total parenteral nutrition is prescribed, then enteral feeding is carried out in small quantities to speed up the intestinal adaptation to the resection. When only 50 cm of the small intestine is preserved, anastomosed with the left half of the colon, parenteral nutrition is used for a long time , sometimes for life, but in some patients, after 1-2 years, sharp hypertrophy of the intestinal epithelium occurs, which forces one to abandon parenteral nutrition (M.S. Levin, 1995).);

Maintenance therapy:

Efficacy has been proven (Randomized prospective studies have been conducted.)

4. Restoration of nutritional status before surgical interventions;

5. Extensive surgical interventions.

Efficacy has not been proven (Randomized prospective studies have been conducted.)

1. Before heart surgery;

2. Long-term respiratory support.

Indications under study:

1. Oncological diseases;

There are no absolute contraindications to the use of parenteral nutrition.

After identifying indications for parenteral nutrition, it is necessary to calculate the necessary components for adequate correction of energy costs, selecting optimal solutions for infusion based on determining the need for protein, fats, carbohydrates, vitamins, microelements and water.


Parenteral nutrition is used when the patient cannot or does not want to eat, and also when nothing can be introduced into the gastrointestinal tract.

Examples of such patients who cannot eat or who cannot have anything administered into the gastrointestinal tract are patients with mechanical or dynamic intestinal obstruction, pancreatitis, or systemic inflammatory response syndrome in generalized sepsis. This group also includes post-operative patients who are expected to be unable to eat for 7 days. This also includes patients with severe vomiting after chemotherapy or pregnancy toxicosis. As a rule, patients with anorexia nervosa or other mental illnesses do not want to eat. The patients described above typically have some degree of malnutrition and dysfunction of various organs and the immune system. Their ability to recover from disease or tolerance to treatment is enhanced by parenteral nutrition.

Pros

The benefits of parenteral nutrition are noted in patients with intestinal obstruction. If it develops in an already malnourished patient, parenteral nutrition should be started immediately to prevent further malnutrition (which plays a role in any intestinal obstruction). If the patient is well-nourished, you can wait up to 5 days before starting intensive nutritional therapy.

Another group of patients in whom the use of parenteral therapy leads to significant improvement are patients with inflammatory bowel diseases. During an exacerbation of the disease, it is necessary to provide rest to the intestine, and therefore the administration of nutrients is carried out intravenously. The timing of support depends on the degree of exhaustion and the presence of systemic sepsis. Another example of intestinal inflammation is radiation enteritis, in which during certain periods it is also necessary to provide rest to the intestine, which implies parenteral nutrition.

Parenteral administration can be used to treat patients with. Often, against the background of intestinal rest, maintenance of good electrolyte levels and nutritional support in the form of parenteral nutrition, the fistulas closed on their own.

Parenteral nutrition also provides enormous benefits to patients with pancreatitis. These patients are characterized by a combination of factors - severe inflammation of the pancreas and the inability to use the intestines. Parenteral nutrition can be used until these problems resolve. If the patient needs it due to pancreatitis, pancreatic necrosis or abscess, then a jejunostomy is formed to switch to enteral nutrition.

Critically ill critical care patients, such as those with sepsis, severe trauma, and burns, may require parenteral treatment early in their hospital stay until dynamic ileus or multiple organ failure associated with such severe conditions resolves.

Parenteral nutrition after surgery requires careful monitoring and a plan to transition the patient to enteral nutrition. Transitional nutrition plays a large role and must be carefully planned specifically for each patient. It is necessary to determine the entire scope of the patient's nutritional needs. Then the dose of parenteral nutrition is reduced and the dose of enteral nutrition is increased. As a result, refeeding syndrome and overfeeding syndrome do not occur. This approach guarantees normal nutrition for patients, while reducing the incidence of infectious complications, and also shortening the length of stay in intensive care and in the hospital in general. Moreover, observations show that parenteral nutrition does not affect patient mortality, but may reduce the incidence of complications in malnourished patients.

Venous access for parenteral nutrition

Parenteral nutrition is administered through an intravenous catheter. Due to the high concentration of parenteral solutions, they are administered through catheters ending in the central vein. Solutions with limited concentrations of amino acids, with or without lipids, can be administered through peripheral veins. Often the duration of catheterization is only a few days, but during this time a large volume of substances is introduced through the nutritional system. On the other hand, catheterization requires central access. The choice of catheterization method depends on the specific clinical situation. The subclavian catheter is most commonly used because it is easy to place (usually on the left side), easy to maintain, and comfortable for the patient. The next most common is an internal jugular catheter. Its placement reduces the risk of lung injury, but it is more difficult to monitor and less comfortable for the patient. Are percutaneous central catheters or PCCs becoming more common? catheters. The advantage of such catheters is that they are inserted peripherally with minimal risk to the patient. This procedure may be performed by a nurse or a special team that performs similar procedures. Patients usually feel fairly comfortable with this catheter, but placement in the cubital fossa should be avoided as catheter occlusion may occur. There is ongoing debate about whether such catheters increase the incidence of venous thrombosis or infectious complications.

Ideally, the parenteral nutrition catheter should not be used to administer other medications. If the catheter has already been used to administer other substances, there are four ways to initiate parenteral nutrition through it:

  1. Use a catheter and monitor for infectious complications.
  2. Use the catheter after flushing with vancomycin and urokinase.
  3. Replace the catheter along the guide.
  4. Use the catheter and replace it only if problems arise.

There is no strong evidence to suggest that either option is superior, but the accepted option should be used as the incidence of catheter-based sepsis is monitored.

Complications of parenteral nutrition

Catheter sepsis is a complication that is often cited as a reason not to resort to parenteral nutrition. One of the problems is the “weakness” of patients receiving parenteral drugs, and therefore their greater tendency to infectious complications. The main risk factor for infectious complications is catheter sepsis, which, if not diagnosed and treated in a timely manner, can lead to septic phlebitis and bacterial endocarditis. It is often quite difficult to make an accurate diagnosis of catheter sepsis, since several components are required for this. For a reliable diagnosis, the patient must have clinical signs of infection, determined microbiologically in the central and peripheral blood of the same microorganism as from the tip of the catheter. If these conditions are met, replace the catheter with a new one, placing it in a different location, and prescribe antibiotic therapy for 14 days. If catheter sepsis is suspected and blood cultures are equivocal, the catheter is changed over the guidewire. If the culture from the tip of the catheter is negative, a new catheter can be placed in the same place, but if microflora is cultured from the tip of the catheter, it must be installed at a different point.

Catheter-induced thrombosis may limit the duration of parenteral nutrition. This depends both on the location of the catheter in the proximal or distal central vein, and on the frequency and severity of complications. In addition, the incidence of this complication is higher in patients whose disease results in a hypercoagulable state (ie, pancreatitis, tumor). Complications of thrombosis of central veins, such as limbs and possible swelling of the head, pulmonary embolism, are life-threatening conditions. Again, thrombosis is more common in the lower extremities than in the upper extremities. A very serious complication of inferior vena cava thrombosis is renal vein thrombosis, leading to renal failure. To avoid these complications, parenteral support mixtures should have low osmolarity and low concentrations of irritants such as potassium; the tip of the catheter should be located in the central vein; Veins of the lower extremities should not be used for parenteral nutrition; low doses of heparin from 10,000 to 12,000 SD per day or a selected dose of Coumadin (warfarin) should be prescribed, ensuring that the INR is 1.5 times higher.

Metabolic complications of enteral nutrition can also occur with parenteral nutrition. In both cases, monitoring the patient’s condition is necessary, and such complications are best prevented. In addition to the complications that arise with enteral nutrition, the following are more typical for parenteral nutrition. Excess carbon monoxide production is a problem in patients whose bodies retain carbon dioxide. This complication is eliminated by reducing the administration of glucose as an energy source and increasing the administration of lipids for these purposes, which allows maintaining the respiratory coefficient of about 0.85. Hepatotoxicity is recognized by an increase in liver function tests. Hepatotoxicity is often a consequence of overnutrition, but can also result from parenteral administration of glucose to patients with stress or sepsis. Reducing the glucose-caloric intake and using a low-calorie diet helps control this problem. Hypoglycemia occurs when parenteral solutions have a high dextrose content and are stopped suddenly. This complication can be avoided by gradual withdrawal of parenteral nutrition.

Parenteral nutrition for various diseases

Liver diseases

Typically, patients with liver failure and malnutrition can receive enteral nutrition, often as an addition to normal meals. In acute hepatitis and/or severe liver failure, severe exhaustion, ascites and complications such as encephalopathy or spontaneous primary peritonitis, better results can be achieved with a course of parenteral nutrition. These patients may have severe malnutrition and are prone to vitamin and mineral deficiencies. Patients with encephalopathy benefit from the addition of branched chain amino acids to parenteral nutrition because it reduces serum levels of aromatic amino acids, which appear to be one of the etiological causes of encephalopathy. Parenteral nutrition for patients with liver failure must be formulated in such a way as to reduce salt and water retention and is therefore carried out in a very limited volume. Patients with liver disease who have undergone liver resection and received parenteral solutions that include branched-chain amino acids have improved surgical outcomes, fewer complications, and a reduced length of hospital stay. In liver failure, it is necessary to limit the administration of lipids to reduce the risk of failure of the reticuloendothelial system.

Parenteral nutrition for pancreatitis

In patients with this diagnosis, the disease can occur either in a mild form, with recovery within a few days, or in an extremely severe form, in which 50% of patients die as a result of pancreatic necrosis and multiple organ failure. Patients with severe forms of pancreatitis require intensive metabolic and nutritional support. Much like in burn patients, pancreatitis-associated intra-abdominal inflammation is characterized by increased metabolism and catabolism. Patients with may have a degree of nutritional deficiency due to protein depletion and lipid malabsorption with vitamin deficiency. It is clear that patients with pancreatitis are highly susceptible to metabolic and hyperglycemic complications of parenteral nutrition. Typically, these patients require early parenteral nutrition to reduce the severity of nutritional deficiencies, especially protein deficiencies. It is important to administer glucose with caution because pancreatitis is characterized by underlying insulin resistance and decreased insulin production. These patients can be fed enterally, with good results and tolerability when formulas are administered below the ligament of Treitz. Gaining access to this section can be quite difficult, therefore, when surgically treating patients with pancreatitis, the advisability of a jejunostomy should always be considered. Enteral nutrition should be designed to limit the introduction of lipids, which can lead to pancreatic insufficiency. If patients have severe steatorrhea, it is advisable to prescribe them medium-chain triglycerides. To reduce exocrine dysfunction, enzyme replacement is effective.

Parenteral nutrition for renal failure

Patients with renal failure are usually characterized by moderate hypermetabolism and catabolism. Catabolism is more severe because protein loss occurs during both hemodialysis and peritoneal dialysis. If such a condition serves as a complication of another disease, then aggravation of nutritional deficiency occurs. It is important to remember that against the background of catabolism, complications of renal failure such as metabolic acidosis, hyperkalemia, and increased levels of creatinine and urea become more severe. Therefore, it is important to promptly diagnose and initiate treatment for expected nutritional problems in patients with renal failure. Parenteral forms must be prescribed with caution, with daily correction to avoid both standard complications and problems associated with excess fluid.

Heart failure

Patients with heart failure may be in a state of cardiac cachexia at the time of initial examination. Enteral support is difficult for patients with heart failure and parenteral nutrition is started. Enteral nutrition should be considered in unstable cardiac patients or those requiring large doses of vasopressor drugs. Care should be taken to avoid refeeding syndrome, particularly in patients with electrolyte disturbances and fluid overload. In a state of failure, the heart needs glucose and calcium, and it is also important to provide nutritional support with a generally small amount of fluid administered. A number of observations indicate that the administration of a combination of glucose, insulin and potassium during a heart attack leads to an improvement in the condition of the myocardium.

Parenteral nutrition for sepsis

Patients with sepsis often have multiple organ failure and systemic inflammatory response syndrome. In such patients, it is important to prevent the development of malnutrition, especially protein malnutrition, which can complicate the course of the disease. Septic patients with systemic inflammatory response syndrome are characterized by increased metabolism, usually within 50% of resting energy expenditure. Patients are characterized by catabolism with losses of urea nitrogen up to 10 g/day. Although enteral nutrition is considered optimal for them, with concomitant dynamic obstruction, enteral nutrition is not tolerated. If enteral administration is not tolerated or must be delayed, intensive parenteral support should be provided. Intensive parenteral nutrition addresses the metabolic disturbances associated with systemic inflammatory response syndrome and also helps reduce nutritional deficiencies, and particularly protein deficiencies. The question of nutritional support for such patients, enteral or parenteral, can be considered only after their general condition and hemodynamics are stabilized. Improvement has been noted when these patients are given medium chain triglycerides and w-3 fatty acids for parenteral nutrition, which are approved for use in Europe and Asia. The administration of w-3 fatty acids reduces the incidence of infectious complications and the overall length of hospitalization, however, work indicating this has been carried out mainly using formulations for enteral administration. It is important to prevent overnutrition syndrome in such patients, which leads to hyperglycemia and cholestasis.

Inflammatory bowel diseases

Patients in this group may experience a spectrum of illnesses with varying degrees of malnutrition. In the most severe forms, patients develop significant wasting, severe weight loss, and life-threatening electrolyte abnormalities associated with diarrhea. Initially, parenteral drugs are prescribed to such patients to combat dehydration and electrolyte disturbances, thereby preventing refeeding syndrome. Over time, these patients can tolerate more volume and, to replace losses, continue to remain on parenteral therapy until adequate enteral nutrition is established. These patients are often on steroid medications and have associated complications, including fluid retention, hypokalemia, hypocalcemia, and hyperglycemia. Nutrition must meet these needs. Another problem for these patients is zinc deficiency.

Toxicosis during pregnancy

This condition can lead to severe exhaustion. Patients often experience secondary electrolyte disturbances caused by vomiting, while nutritional therapy is aimed not only at supporting the pregnant woman, but also the fetus. The patient must be prescribed intensive drug therapy aimed at eliminating toxicosis, however, in case of nutritional deficiency (weight loss of more than 10%), parenteral nutrition is started. In the absence of exhaustion, it is reasonable to treat toxicosis for several days, subject to the correction of water and electrolyte disturbances. Placement of a central catheter should be considered. It is necessary to ensure that the patient receives adequate amounts of vitamins and minerals. It is important, before discontinuing the parenteral route of nutrition, to make sure that the patient receives enough calories from her usual diet.

Parenteral nutrition for cancer patients

Often these patients are severely malnourished, regardless of whether they undergo surgery, chemotherapy or. Patient exhaustion makes treatment less effective. The side effects of radiation and chemotherapy can make the patient seriously ill for several weeks. Concomitant neutropenia makes them more susceptible to infections, including catheter-related sepsis. In patients undergoing bone marrow transplantation, the addition of glutamine to the parenteral route reduces the incidence of septic complications and increases the successful tolerability of the procedure, reducing the overall length of hospital stay. A specially selected diet and traditional cuisine are beneficial for cancer patients. It should not be disputed that nutrition supports the patient, and a tumor should not be a reason to avoid or reduce nutritional support. The inescapable truth is that starving a patient will do little to eliminate the underlying cause.

Intestinal dyskinesia and short bowel syndrome (intestinal dyskinesia)

This condition is becoming increasingly common and has many etiological factors. This group often includes patients receiving parenteral nutrition at home. Patients with short bowel have undergone various types of resection, but this does not mean that they are doomed to constant parenteral nutrition. These patients have a clinical picture of dynamic obstruction involving the small and large intestine, accompanied by pain, nausea, vomiting and bloating. These problems may be associated with chronic use of laxatives and drug addiction, but may also be idiopathic in nature. In acute illness, patients are prescribed parenteral nutrition to eliminate concomitant water and electrolyte disturbances, as well as a lack of proteins and calories. Patients often develop isolated protein wasting, determined by low serum albumin levels. It is very difficult for such patients to switch to enteral nutrition, therefore it is necessary to continue parenteral nutrition to compensate for the lack of nutrition and prevent further malnutrition as a possible cause of dyskinesia. Patients who cannot be transitioned to a normal diet are candidates for parenteral nutrition at home.

Short bowel syndrome develops after resection of a large portion of the intestine due to necrosis, against the background of insufficient blood supply due to embolism of the mesenteric artery, thrombosis of the mesenteric veins, volvulus, and disease. Initially, the patient's condition is severe, but in the future there may be rapid improvement followed by the development of diarrhea. Patients require replenishment of fluid and electrolytes (Na, K, Cl, Ca and P), as well as nutritional support due to protein and energy depletion. As patients recover from the acute phase of the disease, they can be carefully transferred to enteral nutrition, while parenteral nutrition is continued. If this fails, an intestinal rehabilitation program is started. This program uses a combination of glutamine, growth hormone and dietary fiber such as pectin. If all attempts are unsuccessful, the patient requires lifelong parenteral nutrition. In this situation, patients do receive total parenteral nutrition, although this does not mean that they cannot take food by mouth. Such patients eat frequently, although eating causes severe diarrhea, leading to severe fluid and electrolyte disturbances and pharmacological problems.

The article was prepared and edited by: surgeon

Parenteral nutrition (from the Greek para - about + enteron - intestine) is the provision of the body with nutritional ingredients (nutrients) bypassing the gastrointestinal tract. Parenteral nutrition can be complete, when all nutrients are introduced into the vascular bed (the patient does not even drink water), partial (incomplete), when only basic nutrients are used (for example, proteins and carbohydrates), and auxiliary, when oral nutrition is insufficient and requires addition.

Pathophysiology of fasting. In the adult body, the main factor determining the normal balance of metabolic processes is the relationship between food intake and energy expenditure.

If a person is deprived of food, the blood glucose level first decreases and, as a consequence, the secretion of the anabolic hormone insulin. At the same time, the secretion of the catabolic hormone glucagon, which stimulates glycogenolysis in the liver, increases. Thus, glycogen stores in the liver are depleted.

Starting from the second day of fasting, glucagon activates hormone-sensitive lipase, which releases more fatty acids, the oxidation of which increases the level of ketone bodies. If the level of their formation exceeds the rate of utilization, metabolic acidosis develops.

As fasting continues, tissue proteins become energy sources. The labile proteins of the gastrointestinal tract and circulating blood are the first to be mobilized, then the proteins of the internal organs and muscles are broken down, and the last are the proteins of the nervous system.

Thus, fasting in a certain sense can be considered as a state in which the body “devours itself” to satisfy its energy needs.

The main goals of parenteral nutrition are:

  • providing the body with energy (carbohydrates, lipids, amino acids) and plastic material (amino acids);
  • maintaining active protein mass;
  • restoration of existing losses.

Indications for parenteral nutrition. Indications for parenteral nutrition in a hospital include:

  • gastroenterological, When

    a) the patient cannot eat through the mouth (after injuries and interventions in the area of ​​the facial skull, on the digestive tract);

    b) the patient should not eat through the mouth.

Cases of the advisability of enteral nutrition arise in the postoperative period in patients with intestinal obstruction, pancreatic necrosis, after surgical interventions on the gastrointestinal tract, as well as in inflammatory bowel diseases (Crohn's disease, ulcerative colitis, ileus);

  • metabolic(critical conditions accompanied by hypermetabolism), when oral nutrition does not cover the needs of the body of a patient in a critical situation.

This happens with injuries of the skull and brain, severe burns, a state of persistent catabolism after extensive operations and injuries, purulent-destructive processes with the generalization of a highly invasive infection. Parenteral nutrition is recommended for the dystrophic form of congestive heart failure, rehabilitation of deeply asthenized patients, for severe infectious diseases with extreme catabolism, for neurological patients with widespread lesions of the nervous system - from strokes to demyelinating diseases;

  • preoperative preparation in patients to improve the results of surgical intervention in cases where their own protein-energy reserves are limited.

Achieving the described goals is possible only if the following conditions are met: adequate fluid load, a sufficient mass of quickly digestible energy-giving nutrients, ensuring the absorption of a sufficient amount of potassium ions and conditional protein in the form of amino acids in an amount of at least 0.5 g/kg body weight.

Before starting parenteral nutrition, the following measures must be taken:

  • elimination of hemodynamic disorders;
  • replenishment of the deficit of globular volume, plasma volume and circulating blood volume;
  • elimination of severe acid-base disorders;
  • improvement of rheological properties of blood;
  • improvement of macro- and microcirculation.

Calculation of the need for parenteral nutrition. This requires an assessment of the patient's nutrition. To determine the patient’s initial nutritional level, the mass-height index (MHI) is used: MHI = BW (kg)/ m 2 (height).

Normally, MRI is 21-25 kg/m2; less than 20 kg/m2 means a clear decrease in nutrition; 17 kg/m2 – significant reduction in nutrition; less than 16 kg/m2 - extreme exhaustion.

Another indicative indicator of nutritional status is the ratio of actual body weight (FBM) to ideal body weight (BMI), expressed as a %: BMI = Height (cm) - 100.

A decrease in the FMI/BMI ratio to 80% means a mild degree of protein-energy malnutrition; a decrease within 70-80% - moderate deficiency; a decrease to 70% or less—severe degree of protein-energy malnutrition.

One of the most useful biochemical indicators in assessing nutritional status and the effectiveness of nutritional therapy is considered to be creatinine, 98% of which is found in skeletal muscles, mainly in the form of creatinine phosphate. To calculate muscle mass, the creatinine index (CI) is used - the ratio of daily creatinine excretion (g) to height (cm).

Normally IR = 10.5. With a weak degree of protein-energy deficiency, IC = 9.5-8.4.

Determination of energy needs. The minimum energy expenditure of the body under conditions of relatively complete physical and emotional rest (awake, fasting) is defined as basal metabolic rate (BM).

OO = 66.5 + (13.75 x M) + (5 x P) - (6.7 x V) , where M is body weight (kg), P is height (cm), B is age (years).

It is also possible to use a simplified and, accordingly, less accurate formula OO = 25 Ё M.

Calculation of the patient's actual energy requirement (DNE) (kcal/day) is carried out according to the formula

DPE = OO x FA x FU x TF x DMT , where FA is the activity factor: bed rest - 1.1; semi-bed - 1.2; walking - 1.3;

FU factor of injury: after minor operations - 1.1; large operations - 1.3; peritonitis - 1.4; sepsis - 1.5; multiple injuries - 1.6; traumatic brain injury - 1.7;

TF - temperature factor: 38.0°C - 1.1; 39.0°C - 1.2; 40.0°C - 1.3; 41.0°C - 1.4.

The body receives energy mainly from carbohydrates and fats. The oxidation of 1 g of fat releases about 9 kcal (38 kJ), while 1 g of carbohydrate provides about 4 kcal (17 kJ) and 1 g of protein or amino acids provides about 5 kcal (23 kJ).

IN The recommended values ​​for the main components of parenteral nutrition are given. Recommendations for doses of amino acids, glucose, lipids and energy load do not depend on the type of nutrition: total parenteral nutrition, enteral or mixed.

Carbohydrates. In modern parenteral nutrition, glucose is used mainly, although, according to some authors, fructose, sorbitol and xylitol can be used. Considering a number of undesirable effects of glucose in high concentrations (more than 20%) on the acid-base state (acidosis) and myocardium (suppression of its function), the use of glucose solutions in concentrations above 20-25% is not recommended. The maximum rate of glucose utilization during intravenous administration is 0.75 g/kg per 1 hour. Exceeding the noted rate of drug administration leads to osmotic diuresis.

Sorbitol is phosphorylated in the liver to fructose-6-phosphate. Insulin has no effect on either sorbitol or fructose, making them insulin-independent energy sources. When they are used, hyperglycemic acidosis does not occur, which occurs in cases where drugs containing glucose are used for parenteral nutrition.

The daily requirement for glucose ranges from 2 g/kg (no less, otherwise glucose begins to be synthesized from amino acids) to 6 g/kg. Insulin is indicated at the rate of 1 unit per 4-6 g of glucose.

The use of more concentrated glucose solutions (20-40%) is possible for patients who require limiting the volume of infusion.

Amino acids and proteins. Determination of daily protein requirements. Laboratory indicators reflecting protein metabolism include the content of serum albumin, transferrin, prealbumin and retinol-related proteins. The decrease in serum concentrations of these proteins occurs as a result of increased catabolism and decreased protein synthesis. Labile proteins with a short half-life—prealbumin—contain the most information.

Approximately, the following figures for the daily protein requirement are given: the minimum amount is 0.54 g/kg/day, the recommended amount is 0.8 g/kg/day; with increased catabolism (catabolic status) - 1.2 -1.6 g/kg/day.

The adequacy of daily protein intake is judged by the value of nitrogen balance (NA), which determines the difference between nitrogen consumption and losses and is calculated using the following formula:

AB (g) = (amount of protein consumed/ 6.25) - (AM + 4) , where AM is the nitrogen content in urine collected over 24 hours.

The coefficient 6.25 reflects the conversion of nitrogen content into protein content (6.25 g of protein contains 1 g of nitrogen). Amendment 4 takes into account nitrogen excreted not in urine. In case of diarrhea, blood loss or increased rejection of necrotic tissue, extrarenal nitrogen losses are assumed to be 6 g/day.

Knowing the amount of decomposed protein, it is also possible to estimate the daily energy requirement, taking into account that the oxidation of 1 g of protein requires from 150 to 180 kcal.

The modern standard is to use only solutions of crystalline amino acids as the protein component. Protein hydrolysates are currently completely excluded from clinical parenteral nutrition practice.

The total dose of administered amino acids is up to 2 g/kg per day, the rate of administration is up to 0.1 g/kg per hour.

There are no generally accepted requirements (including WHO) for amino acid solutions, but most recommendations for amino acid solutions for parenteral nutrition include the following:

  • solutions must contain all essential amino acids (isoleucine, phenylalanine, leucine, threonine, lysine, tryptophan, methionine, valine, as well as histidine for patients with renal failure and children; tyrosine, cysteine ​​and taurine for children);
  • solutions must contain at least 1/3 of essential amino acids (optimally - about 50%, i.e. the ratio of essential/essential amino acids should be about 1);
  • the leucine/isoleucine ratio should be about 1.6 (no more than 1.6!);
  • for patients with the need to limit the volume of infusion, amino acid solutions with a concentration of 10% or more are preferable;
  • for patients with severe stress, amino acid solutions should contain taurine.

Essential amino acids include isoleucine, phenylalanine, leucine, threonine, lysine, tryptophan, methionine, valine. However, the amino acids listed above are essential only for a healthy and adult body. It should be taken into account that 6 amino acids - alanine, glycine, serine, proline, glutamic and aspartic acids - are synthesized in the body from carbohydrates. Four amino acids (arginine, histidine, tyrosine and cysteine) are synthesized in insufficient quantities.

Amino acids introduced into the body intravenously enter one of two possible metabolic pathways: the anabolic pathway, in which amino acids are linked by peptide bonds into final products - specific proteins, and the metabolic pathway, in which transamination of amino acids occurs.

The amino acid L-arginine promotes the optimal conversion of ammonia to urea, while binding toxic ammonium ions that are formed during protein catabolism in the liver. L-malic acid is necessary for the regeneration of L-arginine in this process and as an energy source for the synthesis of urea.

The presence of non-essential amino acids L-ornithine-aspartate, L-alanine and L-proline in the preparations reduces the body's need for glycine.

Ornithine stimulates glucose-induced insulin production and carbamoyl phosphate synthetase activity, which increases glucose utilization by peripheral tissues, urea synthesis and, in combination with asparagine, reduces ammonia levels.

In addition to “pure” solutions of amino acids, there are solutions with energy and electrolyte additives.

As energy components, in addition to glucose, sorbitol or xylitol can be added, the use of which is not recommended by all authors. Sorbitol is a better solvent for amino acids than glucose, since it does not contain aldehyde and ketone groups and, thus, does not bind to amino groups into complexes that reduce the effect of amino acids.

Thus, Vamin EF contains glucose, aminosol, polyamine and chymix - sorbitol, infezol 40 - xylitol.

A number of standard solutions of amino acids contain Na +, K +, Mg + cations and the Cl - anion.

Sodium ion is the main cation of the extracellular fluid and, together with the chloride anion, is the most important element for maintaining homeostasis. Potassium ion is the main cation of intracellular fluid. It was found that a positive nitrogen balance in the body with total parenteral nutrition can only be achieved by adding potassium ions to the infusion solution.

Magnesium ion is important for maintaining the integrity of mitochondria and for excitation of impulses in the membranes of nerve cells, myocardium and skeletal muscles, as well as for the transfer of high-energy phosphates during the synthesis of adenosine triphosphate. In patients on long-term parenteral nutrition, hypomagnesemia is often accompanied by hypokalemia.

Electrolytes contain the following solutions of amino acids: aminosol, infezol 40 and 100, aminoplasmal E.

The addition of standard solutions of amino acids with B complex vitamins (riboflavin, nicotinamide, panthenol and pyridoxine) is due to their limited reserves in the body and the need for daily administration, especially with long-term total parenteral nutrition.

Specialized solutions of amino acids. In various pathological conditions there are features in the manifestation of metabolic disorders. Accordingly, the quantitative and qualitative need for amino acids changes, up to the occurrence of selective deficiency of individual amino acids. In this regard, for pathogenetically targeted metabolic treatment and parenteral nutrition, special solutions of amino acids (amino acid mixtures of targeted action) have been developed and are widely used in clinical practice.

A distinctive feature of amino acid solutions for patients with liver failure (aminosteryl N-hepa, aminoplasmal hepa (is a decrease in the content of aromatic (phenylalanine, tyrosine) amino acids and methionine with a simultaneous increase in the content of arginine to 6-10 g/l and branched essential amino acids (valine, leucine , isoleucine) - up to 43.2 g/l.

The amount of arginine is increased to ensure the function of the urea cycle and thereby activate ammonia detoxification in the liver and prevent hyperammonemia. The exclusion of aromatic amino acids from mixtures is due to the fact that in case of liver failure, the concentration of aromatic amino acids and methionine in the plasma increases. At the same time, the concentration of branched amino acids decreases. An increase in the transport of aromatic amino acids into the brain enhances the synthesis of pathological mediators that cause symptoms of hepatic encephalopathy. The introduction of drugs with a high content of branched-chain essential amino acids reduces these manifestations. Since these amino acid solutions contain all essential and a wide range of non-essential amino acids, they have a corrective effect on metabolic processes and are used for parenteral nutrition.

For parenteral nutrition and treatment of patients with acute and chronic renal failure, special solutions of amino acids are used: aminosteril KE nephro carbohydrate-free, nephrotect, neframin, with a certain ratio of amino acids. The ratio of essential and non-essential amino acids in such solutions is 60:40. In addition, drugs in this group contain eight essential amino acids and histidine (5 g/l), which makes it possible to reduce azotemia when administered. Due to the interaction of a specially selected spectrum of amino acids with nitrogenous residues, the production of new non-essential amino acids and protein synthesis occur. As a result, uremia decreases. The concentration of amino acids in such solutions is within 57%. There are no carbohydrates and electrolytes or the amount of electrolytes in the solution is minimal.

Fat emulsions. Another source of energy supply is fat emulsions.

Fat emulsions are usually used in long-term nutritional support programs, especially in cases where parenteral nutrition lasts more than 5 days and there is a need to cover the deficiency of essential fatty acids.

Essential fatty acids are structural components of all cell membranes and contribute to the restoration of their structures, permeability and osmotic resistance. In addition, unsaturated fatty acids, as precursors of prostaglandins, thromboxanes and leukotrienes, play an important role in restoring the metabolic and gas exchange functions of the lungs, ensure the transport of fat-soluble vitamins, and are modulators of immune processes.

In addition to the nutritional effect, fat emulsions also perform the following functions:

  • their use resolves the issue of supplying the body with such essential ingredients as unsaturated fatty acids (linoleic and linolenic) and fat-soluble vitamins;
  • fat emulsions suppress excess lipasemia during destructive pancreatitis in the phase of endogenous intoxication, since fat emulsions are destroyed by serum lipase (V.K. Gostishchev et al., 1998);
  • fat emulsions with heparin are used for the restitution of pulmonary surfactants in acute lung injury;
  • studies conducted in the USA (1996) proved the interaction of blood lipoproteins with microbial endotoxins, and the possibility of using exogenous lipoproteins to detoxify the patient’s body with sepsis was established.

There are several types of fat emulsions currently available.

  • Standard (generally accepted) fat emulsions are fat emulsions based on long-chain triglycerides: intralipid, lipovenose.
  • Physical mixtures of emulsions of medium- and long-chain triglycerides (lipovenose, lipofundin MCT/LCT).
  • Fat emulsions based on olive/soybean oils, structured lipids (structolipid).

The clinical effects of using a physical mixture of medium- and long-chain triglycerides do not differ from fat emulsions based on long-chain triglycerides. A meta-analysis by D. Heyland et al (2003) showed the absence of any advantages of a physical mixture of triglycerides over conventional fat emulsions.

Conventional fat emulsions containing long-chain triglycerides with 16-20 carbon atoms should be considered the safest and given preference as a basic fat emulsion, which, depending on the patient’s condition, can be supplemented with an emulsion based on fish oil.

The daily dose of fat emulsions is up to 2 g/kg per day, for liver failure, encephalopathy - up to 1.5 g/kg per day. The rate of administration is up to 0.15 g/kg/hour.

Fat emulsions are contraindicated in cases of lipid metabolism disorders, disorders in the hemostasis system, pregnancy, acute myocardial infarction, various embolisms, unstable diabetic metabolism, shock.

Complications of parenteral nutrition. Among the complications of total parenteral nutrition are mechanical, metabolic, purulent-septic complications and allergic reactions.

Mechanical complications are technical complications of central venous catheterization (pneumothorax, perforation of the subclavian vein/artery, damage to the thoracic lymphatic duct, hemothorax, hydrothorax, paravasal hematoma), various types of embolism, thrombosis and thrombophlebitis.

Metabolic complications include:

  • metabolic disorders: glucose - hyperglycemia, hypoglycemia, hypercapnia; fats - essential fatty acid deficiency syndrome, fat overload syndrome; proteins - hyperammonemia;
  • liver dysfunction;
  • electrolyte disturbances;
  • deficiency conditions (vitamins and microelements);
  • lack of enteral stimulation;
  • endotoxicosis.

Purulent-septic complications involve infection at the site of drug administration and generalization of infection.

Thus, parenteral nutrition can be considered as pharmacotherapy for metabolic disorders and the only way to meet the energy-plastic needs of the body in the post-aggression period, which require specially selected compositions of nutrients.

Literature
  1. Lozhkin S. N., Sviridov S. V. Parenteral nutrition. A new approach to the implementation of parenteral nutrition - “three in one” technology // Consilium medicum. 2005. T. 07(6). www.consilium-medicum.com/media/consilium/05_06/478.shtml.
  2. Kostyuchenko A. L., Kanyuchevsky A. V. Modern possibilities of parenteral nutrition // Bulletin of intensive care. 1998.2 www.medi.ru/doc/8180203.htm.
  3. Paul L. Marino. Intensive care / ed. A. I. Martynova. M.: Geotar Medicine, 1999. P. 471-509.
  4. Materials of the XVI session of the Academic School-Seminar named after. A. M. Ugoleva “Modern problems of physiology and pathology of digestion.” 2001. T. XI. No. 4. pp. 102-109.
  5. AKE Recommendations: Enteral and parental nutritional support in adults. Austrian Society of Clinical Nutrition, 2002.
  6. Sobotka L. (Ed). Basics in clinical nutrition. Edited for ESPEN Courses. Galen 2nd ed., Prague, 2000.
  7. A.S.P.E.N. Board of Directors and the Clinical Guidelines Task Force. Guidelines for the use of parenteral and enteral nutrition in adult and pediatric patients. JPEN 2002; 26: supplement.
  8. French-Speaking Society for Parenteral and Enteral Nutrition. Perioperative artificial nutrition in elective adult surgery. Consensus statement. Clin Nutr 15:223–229.
  9. Heyland D. K., Dhaliwal R. D., Drover J. W. et al. Canadian Clinical Practice Guidelines for Nutrition support in mechanically ventilated, critically ill adult patients // J Parenteral Enteral Nutrition. 2003; 27: 355-373.

V. G. Moskvichev, Candidate of Medical Sciences
R. Yu. Volokhova
MGMSU, Moscow

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Viral hepatitis in children

The lecture “Viral hepatitis in children” presents data on viral hepatitis A, B, C, D, E, F, G in children. All clinical forms of viral hepatitis, differential diagnosis, treatment and prevention that currently exist are presented. The material is presented from a modern perspective and is intended for senior students of all faculties of medical universities, interns, pediatricians, infectious disease specialists and doctors of other specialties who are interested in this infection.