Types of parenteral nutrition. Parenteral nutrition in therapeutic practice Advantages of parenteral nutrition

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

Total parenteral nutrition

Total parenteral nutrition (TPN) consists of intravenous administration of all nutritional components (nitrogen, water, electrolytes, vitamins) in quantities and ratios that most closely correspond to the body's needs at the moment. Such nutrition is usually needed during complete and prolonged fasting.

The purpose of PPP is to correct disorders 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 feed enterally. These include the following categories of patients:

1. Patients who are unable to eat 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 is 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 nutritional status who are temporarily (for one reason or another) unable to eat and, in order to avoid excessive malnutrition, 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. Normal nutrition in such patients aggravates the symptoms of the disease and worsens the general condition of the patients. Transferring them to PPP accelerates the healing of fistulas and reduces the volume of inflammatory infiltrates.

4. Patients with a prolonged coma, when feeding through a tube is impossible (including after brain surgery).

5. Patients with severe hypermetabolism or significant protein losses, for example in patients with injuries, burns (even in cases where normal nutrition is possible).

6. To provide nutritional support to patients receiving therapy for malignant tumors, especially when malnutrition is due to decreased food intake. Often the consequences of chemotherapy and radiation treatment is 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 debilitated patients before upcoming surgical treatment.

8. Patients with mental anorexia. TPN 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 the entry of food or gastric contents into the respiratory tract.

Partial parenteral nutrition

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

Indications for partial parenteral nutrition

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

List of diseases for which partial parenteral nutrition is indicated:

Gastric 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);

Severe catabolism in the early period after major extraperitoneal operations;

Purulent-septic complications of injuries;

Sepsis;

Hyperthermia;

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

Oncological diseases;

Severe endo- and exotoxicosis;

Severe diseases of the blood system;

Acute and chronic renal failure.

For quotation: Kotaev A.Yu. Principles of parenteral nutrition // RMZh. 2003. No. 28. S. 1604

MMA named after I.M. Sechenov

P Nutrition is an important component of the treatment of many diseases and traumatic injuries.

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 and diseases internal organs, heavy 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, disturbances in water-electrolyte balance, acid-base status, hemostasis and rheological properties blood. At the same time, during stress, through the pituitary gland, adrenal cortex, thyroid gland basal metabolism is stimulated, 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 loss squirrel.

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).

Nutritional status assessment

Many methods have been proposed for assessing nutritional status. Some of them are shown in Table 1.

Anamnesis (lack of appetite, nausea, vomiting, weight loss) and examination of the patient (muscle atrophy, loss of subcutaneous fat layer, hypoproteinemic edema, symptoms of vitamin deficiency and deficiency of other nutrients) are important for assessing nutrition.

Choosing the optimal method of nutritional support

Artificial nutritional support for patients can be provided in the form of parenteral and/or enteral nutrition.

There are total parenteral nutrition, in which nutrients are provided only by intravenous infusions (usually central veins are used) and additional parenteral nutrition through peripheral veins (prescribed for a short period as an addition to enteral nutrition).

The algorithm for rational choice of nutritional support is presented in Figure 1.

Indications for parenteral nutrition

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:

Proven effectiveness ()

1. Intestinal fistulas;
2. Renal failure (acute tubular necrosis);
3. Short bowel syndrome (After extensive resection small intestine Total parenteral nutrition is prescribed, followed by small amounts of enteral feeding to speed up the intestinal adaptation to 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) .) ;
4. Burns;
5. Liver failure (acute decompensation in liver cirrhosis).

Efficacy not proven (Randomized prospective studies were conducted.)

1. Crohn's disease (In Crohn's disease affecting the small intestine, total parenteral nutrition leads to remission in most patients. In the absence of intestinal perforation, the remission rate is 80% (including long-term remission - 60%). The probability of fistula closure is 30-40%, the effect is usually stable. In ulcerative colitis and Crohn's disease affecting the colon, total parenteral nutrition has no advantage over regular meals.) ;
2. Anorexia nervosa.

Maintenance therapy:

Proven effectiveness (Randomized prospective studies were conducted.)

1. Acute radiation enteritis;
2. Acute intoxication during chemotherapy;
3. Intestinal obstruction;
4. Restoration of nutritional status before surgical interventions;
5. Extensive surgical interventions.

Efficacy not proven (Randomized prospective studies were conducted.)

1. Before heart surgery;
2. Long-term respiratory support.

Indications under study:

1. Oncological diseases;
2. Sepsis.

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

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

Calculation of energy needs

Energy costs depend on the severity and nature of the disease or injury (Table 2).

For a more accurate calculation of energy costs, the basal metabolic rate is used.

Basal metabolism represents the minimum energy requirements under conditions of complete physical and emotional rest, comfortable temperature and 12-14 hour fasting.

The amount of basal metabolism is determined using Harris-Benedict equations (Harris-Benedict):

for men: OO = 66 + (13.7xW) + (5xP) - (6.8xW)

for women: OO = 655 + (9.6xW) + (1.8xP) - (4.7xW)

BT = basal metabolic rate in kcal, BT = body weight in kg, P = height in cm, B = age in years.

Normally, true energy expenditure (IRE) exceeds basal metabolism and is estimated using the formula:

IRE = ООхАхТхП, Where

A - activity factor:

T - temperature factor (body temperature):

P - damage factor:

On average, proteins account for 15-17%, carbohydrates - 50-55% and fats - 30-35% of the energy released (depending on specific metabolic conditions and diet).

Calculation of protein needs

Nitrogen balance is used as an indicator of protein metabolism (the difference between the amount of nitrogen entering the body with proteins and lost in various ways) (Table 3).

The determination of nitrogen loss by the urea content in daily urine is also used (urea in grams x 0.58).

The loss of nitrogen corresponds to the loss of protein and leads to a decrease in body weight (1 g nitrogen = 6.25, protein = 25 g muscle mass)

The main purpose of introducing proteins is to maintain a balance between protein intake and consumption in the body. At the same time, if enough non-protein calories are not supplied at the same time, protein oxidation increases. Therefore, the following ratio between non-protein calories and nitrogen should be observed: the number of non-protein calories/nitrogen in grams = 100-200 kcal/g.

The nitrogenous component in the parenteral nutrition diet can be represented by protein hydrolysates and amino acid mixtures obtained by synthesis. The use of undigested protein preparations (plasma, protein, albumin) for parenteral nutrition is ineffective due to the too long half-life of the exogenous protein.

Protein hydrolysates used for parenteral nutrition are solutions of amino acids and simple peptides obtained by hydrolytic breakdown of heterogeneous animal proteins or plant origin. Protein hydrolysates are less efficiently utilized by the body (compared to amino acid mixtures) due to the presence of high molecular weight peptide fractions in them. It is more justified to use amino acid mixtures, from which specific organ proteins are then synthesized.

Amino acid mixtures for parenteral nutrition must meet the following requirements: contain an adequate and balanced amount of essential and essential amino acids; be biologically adequate, i.e. so that the body can transform amino acids into its own proteins; don't call adverse reactions after they enter the vascular bed.

Contraindications to the administration of protein hydrolysates and amino acid mixtures:

1. impaired liver and kidney function - liver and kidney failure (special amino acid mixtures are used);

2. any forms of dehydration;

3. states of shock;

4. conditions accompanied by hypoxemia;

5. acute hemodynamic disorders;

6. thromboembolic complications;

7. severe heart failure.

Calculation of carbohydrates

Carbohydrates are the most accessible sources of energy for the patient's body. Their energy value is 4 kcal/g.

For parenteral nutrition, glucose, fructose, sorbitol, and glycerol are used. The minimum daily requirement of tissues for glucose is about 180 g.

It is optimal to administer a 30% glucose solution with the addition of insulin (1 unit of insulin per 3-4 g of dry matter of glucose). In elderly patients, in the first 2 days after surgery, it is advisable to reduce the glucose concentration to 10-20%.

The administration of glucose reduces gluconeogenesis, so glucose is included in parenteral nutrition not only as an energy carrier, but also to obtain a protein-saving effect.

Excessive glucose administration, however, can cause osmotic diuresis, with loss of water, electrolytes and the development of hyperosmolar coma. An overdose of glucose leads to increased liponeogenesis, in which the body synthesizes triglycerides from glucose. This process occurs mainly in the liver and adipose tissue and is accompanied by very high production of CO 2, which leads to a sharp increase in minute tidal volume and, accordingly, respiratory rate. In addition, fatty infiltration of the liver may occur if hepatocytes are unable to remove the resulting triglycerides into the blood. Therefore, the glucose dose for adults should not exceed 6 g/kg body weight per day.

Fat calculation

Fats are the most beneficial source of energy (energy value is 9.3 kcal/g).

Fats account for 30-35% of daily calorie intake, most of which are triglycerides (esters consisting of glycerol and fatty acids). They are a source of not only energy, but also essential fatty acids, linoleic and a-linolenic acids - precursors of prostaglandins. Linoleic acid takes part in the construction of cell membranes.

The optimal dose of fat in clinical settings is 1-2 g/kg body weight per day.

The need for fats during parenteral nutrition is provided by fat emulsions.

The administration of fat emulsions in isolated form is impractical (ketoacidosis occurs), therefore, simultaneous administration of a solution of glucose and a fat emulsion is used with a calorie ratio of 50:50 (normally 70:30; for polytrauma, burns - 60:40).

The most widely used drugs in our country are Intralipid and Lipofundin. The advantage of Intralipid is that at 20% concentration it is isotonic with plasma and can be administered even into peripheral veins.

Contraindications for the administration of fat emulsions are basically the same as for the administration of protein solutions. It is not advisable to administer fat emulsions to patients with lipid metabolism disorders, diabetes mellitus, thromboembolism, acute myocardial infarction, pregnancy.

Water calculation

The need for water during parenteral nutrition is calculated based on the amount of losses (urine, feces, vomit, breath, drainage, fistula, etc.) and tissue hydration. Clinically, this is assessed by the amount of urine and its relative density, skin elasticity, tongue moisture, presence of thirst and changes in body weight.

Normally, water requirements exceed diuresis by 1000 ml. In this case, the endogenous formation of water is not taken into account. Loss of proteins, electrolytes and glucosuria significantly increase the body's need for exogenous water.

For parenteral nutrition, it is recommended to administer 30-40 ml of water per 1 kg of body weight for adults. It is believed that the digital number of kilocalories administered should correspond to the digital value of the volume of fluid transfused (in milliliters).

Calculation of electrolytes

Electrolytes are integral components of total parenteral nutrition. Potassium, magnesium and phosphorus are necessary for optimal nitrogen retention in the body and for tissue formation; sodium and chlorine - to maintain osmolality and acid-base balance; calcium - to prevent bone demineralization (Table 4).

To cover the body's need for electrolytes, the following infusion media are used: isotonic sodium chloride solution, balanced solutions of electrolytes (lactosol, acesol, trisol, etc.), a solution of 0.3% potassium chloride, solutions of chloride, calcium gluconate and lactate, lactate and magnesium sulfate.

Calculation of vitamins and microelements

Parenteral nutrition involves the use of vitamin complexes and microelements. An amount of vitamins and microelements sufficient to meet daily requirements should be added to the basic solution for parenteral nutrition (Tables 5 and 6). The use of vitamins in the diet is justified with full amino acid supply, otherwise they are not absorbed and are excreted mainly in the urine. Excessive amounts of fat-soluble vitamins (A, D) should not be administered due to the risk of hypercalcemia and other toxic effects.

For parenteral nutrition, special mixtures of vitamins and microelements are used.

IN last years produce combined preparations containing amino acids, mineral elements and glucose.

Conditions for the effectiveness of parenteral nutrition

Before parenteral nutrition, the patient’s condition must be stabilized and hypoxia eliminated, since complete absorption of the components of parenteral nutrition occurs only in aerobic conditions. Therefore, in the first hours after major operations, trauma, burns, in terminal conditions and shock, only glucose solutions can be used to centralize the blood circulation.

The rate of administration of drugs should correspond to the rate of their optimal absorption (Table 7).

When calculating the daily calorie content of parenteral nutrition, the contribution of protein should not be taken into account, because otherwise the lack of energy will lead to the burning of amino acids and the synthesis processes will not be fully realized.

The introduction of parenteral nutrition should begin with a solution of glucose with insulin (1 unit per 4-5 g of dry matter of glucose). After infusion of 200-300 ml of glucose solution, an amino acid preparation or protein hydrolysate is added. Subsequently, the amino acid mixture or protein hydrolysate is administered along with glucose, electrolytes and vitamins. It is advisable to administer amino acids, protein hydrolysates and 30% glucose at a rate of no more than 40 drops per minute. Fat emulsions are allowed to be poured together with solutions of amino acids and hydrolysates. It is not recommended to administer them simultaneously with electrolytes, since the latter contribute to the enlargement of fat particles and increase the risk of fat embolism. The rate of administration of the fat emulsion should initially not exceed 10 drops per minute. If there is no reaction, the speed can be increased to 20-30 drops per minute. For every 500 ml of fat emulsion, 5000 units of heparin are administered.

For timely correction of parenteral nutrition, clinical and laboratory methods nutritional effectiveness assessments.

Features of artificial nutrition in some conditions

Kidney failure

For patients with renal failure, the volume of fluid administered, the amount of nitrogen and electrolytes are of particular importance. For acute renal failure If dialysis treatment is not carried out, total parenteral nutrition is carried out with concentrated solutions (70% glucose, 20% fat emulsion, 10% amino acid solution), which reduces the volume of fluid and provides a sufficient amount of energy. The nitrogen content in the nutritional mixture is reduced (when calculating the daily protein requirement, the norm is 0.7 g/kg), and the content of potassium, calcium, magnesium and phosphorus is also reduced.

During dialysis treatment, the amount of protein can be increased to 1.0-1.5 g/kg/day.

Liver failure

With liver failure, all types of metabolism are affected, and primarily protein metabolism. Impaired urea synthesis leads to the accumulation of ammonia and other toxic nitrogenous compounds in the blood. Artificial nutrition should meet the body's needs for proteins and other nutrients, but not be accompanied by the appearance or intensification of encephalopathy.

Total parenteral nutrition with reduced nitrogen content is used; when calculating the daily protein requirement, the norm is 0.7 g/kg of weight. With ascites, in addition, the volume of the nutritional mixture is limited and the sodium content is reduced.

Disorders of protein metabolism in liver failure lead to amino acid imbalance (increased concentrations of aromatic acids phenylalanine and tyrosine, as well as decreased concentrations of branched amino acids isoleucine, leucine and valine) (J.E. Fischer et al., 1976). These disorders cause encephalopathy and, along with protein restriction, are main reason high catabolism in such patients.

With a decrease in liver function and shunting of portal blood, the balanced amino acid composition in the plasma is disrupted (especially amino acids - precursors of central monoamine neurotransmitters), which is accompanied by a decrease in the level of neurotransmitters in the central nervous system and is one of the causes of encephalopathy.

Correction of amino acid imbalance is achieved by introducing an adapted amino acid mixture, in which the fraction of aromatic amino acids is reduced and the fraction of branched amino acids is increased. Because these amino acid solutions contain all essential amino acids and a wide range of non-essential amino acids, they can also be used for parenteral nutrition in liver failure.

Parenteral nutrition for liver failure is recommended in the following doses: adapted amino acids - up to 1.5 g/kg body weight per day, glucose - up to 6 g/kg body weight per day and fats - up to 1.5 g/kg body weight per day .

Heart and respiratory failure.

In case of heart failure, sodium intake is limited and the volume of the nutritional mixture is reduced. Patients with respiratory failure nutritional mixtures with a low glucose content and a high fat content are prescribed. Replacing the energy source from carbohydrates to fats reduces CO 2 production and the risk of hypercapnia. Fat has a lower respiratory quotient than carbohydrates (0.7 and 1.0, respectively). Patients with hypercapnia should receive 40% of their energy in the form of fat emulsion.

Complications of parenteral nutrition

With parenteral nutrition, as with other types of infusion therapy, allergic and post-transfusion reactions are possible.

In addition, there are several other types of complications of parenteral nutrition:

1. Technical (5%):
- air embolism;
- artery damage;
- damage to the brachial plexus;
- arteriovenous fistula;
- perforation of the heart;
- catheter embolism;
- catheter displacement;
- pneumothorax;
- thrombosis of the subclavian vein;
- damage to the thoracic duct;
- damage to veins.
2. Infectious (5%):
- infection at the venipuncture site;
- “tunnel” infection;
- catheter-associated sepsis.
3. Metabolic (5%):
- azotemia;
- excessive fluid administration;
- hyperglycemia;
- hyperchloremic metabolic acidosis;
- hypercalcemia;
- hyperkalemia;
- hypermagnesemia;
- hyperosmolar coma;
- hyperphosphatemia;
- hypervitaminosis A;
- hypervitaminosis D;
- hypoglycemia;
- hypocalcemia;
- hypomagnesemia;
- hyponatremia;
- hypophosphatemia.
4. Liver dysfunction.
5. Gallstone disease.
6. Metabolic disorders bone tissue.
7. Micronutrient deficiency.
8. Respiratory failure.

Parenteral nutrition is used when it is impossible or impossible to meet the body's needs naturally, feeding through the mouth or tube. Indications: toxic conditions: intractable vomiting, burn disease, multiple combined injuries, maxillofacial trauma, cachexia, anorexia, in oncology, etc.

Artificial nutrition (solutions and mixtures) is considered one of the key types of therapy during the resuscitation period. It is in demand in all medical fields: surgery, gastroenterology, oncology, and so on. The composition of artificial nutrition mixtures includes nutritional microcomponents (amino acids). The remedies are concentrated on correcting all kinds of damage in the patient’s body. There are two types of nutritional treatment: enteral and parenteral.

What is parenteral nutrition?

Parenteral nutrition (PN) is the introduction of extremely important nutrients and amino acids into the blood of a sick person. An artificial type of nutrition (mixtures and solutions) is administered intravenously. The drug can complement oral food intake, and can also serve as a remedy that is used in small portions, depending on the test results of the patient per day. If the doctor indicates complete PN, the solution is administered intravenously in exactly the amount that meets the patient’s daily need for it.

In addition to the fact that sick people receive different kinds parenteral drugs (amino acids) in hospital settings, patients currently have the opportunity to administer some types of parenteral mixtures at home. This will help them lead a somewhat fulfilling lifestyle.

Artificial parenteral nutrition (mixtures and solutions) allows for a long time to meet the patient's needs for energy, amino acids and protein in sufficient quantities. The composition of the types of solutions and mixtures in different age groups has significant differences. Correct and timely use of artificial means of PN can reduce the mortality of patients (indications of medical reports), and also reduces the time of stay of patients in a hospital.

Indications for the use of parenteral nutrition drugs

Indications for the use of parenteral artificial drugs can be total, that is, all amino acids and other components of the drug enter the blood intravenously, or mixed, when parenteral solutions and mixtures are combined with the administration of other nutritional agents. Medical indications for switching to special artificial mixtures and drugs are all diseases and various pathological conditions that are associated with a violation of the organic or functional failure of the gastrointestinal tract. Indications may also include preparing a patient with severe malnutrition for surgery, radiation, chemotherapy, and so on. In most cases, such situations occur with intestinal ischemia or complete obstruction. It is important to know that parenteral nutrition is never prescribed as the only means of nutrition.

Reason for appointments artificial species mixtures (amino acids) - test indications about severe protein deficiency in patients; it occurs in the following indications:

• catabolic reaction of the patient to surgery, the result of the reaction is the breakdown of protein under the influence of hyperproduction of hormones of the adrenal cortex;
• as the body’s energy requirement increases, protein breakdown actively occurs;
• in the postoperative period, intravascular protein is lost into the wound cavity and through drainages;
• if there is evidence of a nutritional factor in the postoperative period, this is also the cause of protein breakdown.

The most important purpose of the indications for artificial PN is the restoration of the destroyed metabolism of the gastrointestinal tract.

Patients who are administered artificial parenteral solutions are also prescribed various types of drugs and mixtures that are sources of energy (amino acids, carbohydrates, alcohols, fats). For example, in cases of severe dysproteinemia, peritonitis, acute pancreatitis and others.

Contraindications to prescribing drugs peri

Relative contraindications to the use of artificial nutrients are:

• intolerance to individual components of the mixture or solution;
• the patient's state of shock;
• overhydration.

Methods for using certain types of PP products

There are three main types of nutrients used in PN: triacylglycerol, glucose and amino acids. The solutions are combined in such a way as to ensure a normal level of metabolism in the patient’s body.

The drug is injected into a vein slowly. Fluid balance is maintained with 5% glucose solution. At the same time, other types of nitrogen and energy preparations are administered. Simple insulin is also added to the nutrient solution.

The use of the drug involves daily blood tests, body weight, urea levels, glucose, accurate fluid balance and others. Kidney tests should be taken twice a week to determine the amount of protein in the blood plasma. Complications during the administration of PN drugs are manifested by chills, increased body temperature, and allergic manifestations become more active.

Parenteral nutrition (PN) is prescribed to patients who are unable to feed themselves or for additional nutritional support. PP preparations are used for injection into a vein, bypassing digestive tract. They enter the blood and lead to quick elimination violations.

The amount of solution of administered amino acids for parenteral nutrition is calculated for each person individually, taking into account the severity of the condition, age, and specific pathology. In the future, their number and composition will be adjusted. The use of parenteral nutrition as part of complex therapy significantly improves well-being.

Enteral nutrition is less expensive than parenteral nutrition, which causes more complications, suppresses the immune system, and significantly increases the risk of infection.

What is parenteral nutrition?

PN involves the introduction through a vein of all necessary nutrients (components) to alleviate the patient’s condition in case of insufficient supply of necessary proteins, fats, carbohydrates, vitamins and minerals from the outside. This maintains internal homeostasis - the constancy of the acid-base and water-electrolyte composition of the blood. At the same time, the body receives the required amount of all nutrients.

PN is of particular importance in patients with diseases of the digestive tract who require resuscitation care. Severe pathology is accompanied by a significant deficiency of proteins, especially after suffering. Increased breakdown of proteins occurs due to:

• high energy needs of the body;
• large loss of protein through the wound surface and drainages;
• low amount of proteins supplied with food - after surgery the patient cannot eat properly, and their absorption is impaired;
• hormones of the adrenal cortex that are intensively produced after surgery in response to injury.

At chronic diseases the absorption of all food components is impaired.

The clinical effect of parenteral nutrition is aimed at correcting all emerging disorders. With PN, all components are introduced ready-made in sufficient quantities and are immediately absorbed. For injuries with large blood loss and in cancer patients, a blood substitute and injectable iron preparations (Likferr, Ferinject) are used. Pregnant women and when feeding a child should administer these medications with caution due to the high risk of allergic reactions.

Basic principles and types of parenteral nutrition

For successful complex therapy, which includes PN, the following principles of administering nutrient solutions are applied:

• timely start;
• continuity of administration until the final restoration of impaired functions;
• adequacy in composition, volume of injected liquid, ratio of components, their energy value.

A classification is used according to which all PPs are divided:

• full – all components are introduced into the vascular bed, the patient does not even drink water;
• partial - only the missing components (amino acids or carbohydrates) are administered parenterally;
• auxiliary - hyperalimentation - necessary excess nutrition for severely ill patients, enteral (through the mouth) or parenteral, when regular food is not enough and the administration of solutions is required;
• combined - combination with probe.

More often, nutrition through a vein is required for a short time (from 2–3 weeks to 3 months), but long-term intestinal pathology can significantly weaken the body, especially in children. The period of use of PP increases beyond 3 months.

Parenteral nutrition products

Drugs used for intravenous nutrition should:

• have the required amount and ratio of nutrients;
• simultaneously flood the body;
• have a detoxifying, detoxifying and stimulating effect;
• be harmless and easy to administer.

For parenteral nutrition, mixtures are used that include all the required proteins, fats and carbohydrates.

Since proteins are absorbed in a split form, the main source of protein during PN is the amino acids of protein hydrolysates: Polyamine, Levamin-70, Vamin.

Fat emulsions: Intralipid, Lipofundin, Lipozin.

Carbohydrates:

• glucose - with a solution concentration of 5–50%;
• fructose (10 and 20%), which, compared to glucose, irritates the vein walls to a lesser extent.

This is an incomplete list of ready-made artificial mixtures that can be purchased at a pharmacy as prescribed by a doctor.

Indications and contraindications

Parenteral nutrition is the primary method of nutrition primarily for those undergoing surgery. PP is prescribed for negative nitrogen balance. After surgery, it is 15–32 g of protein per day, which corresponds to a loss of 94–200 g of tissue proteins or 375–800 g of muscle protein. This is data for calculating nutrition for patients in need of intensive care. They are indicated for complete PN due to a pronounced negative nitrogen balance and the inability to obtain food naturally, which results in increased catabolism (tissue breakdown) and inhibition of anabolism (the construction of new cells).

In addition to the postoperative period, indications for complete PN are:

• starvation or damage to the digestive tract;
• extensive burns;
• pathology of the liver, kidneys, pancreas, intestines, hyperthermia, when increased protein breakdown occurs;
• infections with severe dehydration and malabsorption due to intestinal damage (cholera, dysentery);
• mental illness (anorexia);
• coma or prolonged unconsciousness.

According to the “7 days or 7% weight” rule, PN is prescribed to a patient who has not eaten for 7 days or has lost 7% of weight during daily weighing in the inpatient department. With a loss of body weight of more than 10%, cachexia develops as a consequence of loss of calories and protein.

After radiation or chemotherapy, PN is prescribed to enhance adaptation and eliminate the harmful effects of these treatments. The prescription of PN occurs individually for each patient.

In general, indications for PP come down to three points:

• inability to feed naturally in stable patients for 7 days, in depleted patients - in a shorter period of time;
• the need to create functional rest in case of damage to any digestive organ (pancreas, intestines, stomach);
• hypermetabolism, in which normal nutrition does not meet the body's needs for essential nutrients.

PP is not carried out in the following cases:

• patient refusal;
• lack of improvement in prognosis when using PN;
• the possibility of introducing nutrition in other ways, covering the needs for necessary substances.

Parenteral nutrition through veins

The main route of administration of PP is intravenous. Manipulation is carried out through a peripheral or central vessel.

In the first case, the infusion is carried out through a dropper - through a needle, cannula or catheter inserted into the vessel. It is used if PN is needed during the day or in the case of PN being used as an additional method of nutrition.

In the second case, the solution is infused through a catheter inserted into the central vessel. This need arises for long-term PN, when the patient is in serious condition or coma. Mixtures are administered through the subclavian vein, less often - the femoral vein, and even less often - the jugular vein.

Peripheral veins cannot be used to administer hypertonic concentrated solutions. Their small diameter, low blood flow speed, and soft walls lead to phlebitis or thrombosis. In large highways, these mixtures, due to the larger size of the vein and high blood speed, are diluted and do not cause such changes.

The osmolarity of solutions during intravenous administration is also taken into account in order to avoid the development of dehydration. Solutions that are close to physiological in density should be injected into the peripheral blood. Normal blood plasma osmolarity is 285–295 mOsm/L, and for most PN solutions it is significantly higher than these figures - 900 mOsm/L. Infusion of such substances (exceeding 900 mOsm/l) into a peripheral vessel is strictly prohibited.

When conducting PP, you must follow some rules:

1. Proteins, lipids, carbohydrates are introduced only in the form of their components, which immediately enter the tissues: amino acids, fat emulsions, monosaccharides.
2. High osmolarity mixtures are injected only into large veins.
3. The system for administering the drug is changed to a new one once a day.
4. Compliance with the infusion rate and volume, the determination of which takes into account the patient’s weight: 30 ml/kg in a stable condition. For a severe patient the numbers increase.
5. All irreplaceable components of PP are used simultaneously.

Intravenous infusion of solutions is divided according to duration:

• to cyclic (within 8 hours);
• extended (12-18 hours);
• constantly throughout the day.

Catheter placement

For long-term PN, solutions and mixtures are administered through large central veins, for example, the subclavian vein. Seldinger catheterization is widely used.

Algorithm for installing a venous catheter:

• puncture of the vessel with a needle;
• passing the conductor through the needle into the vein and removing the needle;
• threading the catheter onto the guidewire;
• insertion of a catheter into a vessel, removal of a guidewire.

The surgical field is pre-treated with an antiseptic. Before the procedure, the treatment is carried out again. In this case, the patient lies on his back with his head down to prevent air embolism.

Energy balance

PP power supply schemes are calculated taking into account energy needs. They depend on age, gender, and degree of catabolism.

There is a special formula for calculation - Harris-Benedict. It is used to calculate the main metabolism - resting energy expenditure (REC). With a sedentary lifestyle or small height and body weight, the obtained indicators turn out to be overestimated.

Formula for calculating energy metabolism:

• in men: 66 + (13.7 x B) + (5 x P) - (6.8 x age);
• in women: 655 + (9.6 x B) + (1.8 x P) - (4.7 x age).

B - weight in kg, P - height in cm.

To calculate the energy requirement per day, the EDP is multiplied by the metabolic activity factor: these are ready-made figures, and are calculated for different pathologies:

• surgical (1–1.1);
• several fractures at the same time (1.1–1.3);
• infectious (1.2–1.6);
• burn (1.5–2.1).

The approximate calculated value of EZP is 25 kcal/kg/day. When multiplied by the metabolic activity factor (on average 1.2–1.7), the result is 25–40 kcal/kg/day.

Protein requirement

Anyone should consume 0.8 g/kg body weight of protein per day. The need for protein depends on the severity of the patient’s condition: it increases to 2.5 g/kg of weight in pathology.

When carrying out PP, amino acids, which are components of protein, are used mainly as building materials in anabolic processes, and not as a source of energy. Only in case of burns and sepsis is protein used by the body simultaneously for two purposes. This is due to low absorption of lipids and carbohydrates in such patients. In this pathology (severe injuries, septic conditions), catabolic processes predominate, so the introduction of solutions with a branched chain amino acid composition is effective:

• leucine;
• isoleucine;
• valine

Thanks to their use:

• blood counts normalize faster;
• the number of delayed-type allergies decreases.

Nitrogen balance

The nitrogen balance is determined by the nitrogen received from proteins and the nitrogen consumed. Accordingly, the balance can be:

• zero – with equal intake and consumption of nitrogen in the body;
• negative – when nitrogen decomposition exceeds its intake;
• positive – when the supply of nitrogen is greater than its consumption.

A positive balance is considered when the body’s energy needs are fully covered. U healthy person This condition is observed even with zero energy supply due to the body’s reserves of nutrients.

A negative nitrogen balance occurs:

• with severe stress (sometimes it does not even recover to zero, despite low energy expenditure);
• in patients.

Creating a positive nitrogen balance is the golden rule of parenteral nutrition: 1 g of nitrogen is contained in 6.25 g of protein (16%). Having determined the amount of nitrogen, the required amount of protein is calculated based on the allocated nitrogen.

Nutrients

The software must include all the necessary components:

• carbohydrates;
• lipids;
• proteins;
• electrolyte solutions;
• vitamin preparations;
• microelements.

These nutritional constituents must be monitored daily.

Parenteral Nutrition Supplements

For PP, a solution is used that does not contain other components. They are added to the mixture if necessary based on the patient’s condition to maintain homeostasis. Electrolytes that should be present in the solution for intravenous infusion: sodium, potassium, calcium, phosphorus. If necessary, vitamins and microelements are also added.

Electrolytes

The mixtures introduced must have mineral composition, including the main necessary elements.

Potassium is found in large quantities inside the cell. It is lost during forced diuresis, and when metabolism is activated, the need for it increases sharply. With PP, the amount of potassium increases - hyperglycemia is determined. Due to the presence of glucose in the composition of PP, the amount of insulin in the blood increases. This activates K+ Na+ - ATPase and the flow of K+ ions from the intercellular fluid into the cell.

Sodium is the main element of intercellular fluid. It is determined in blood plasma. It is injected into a vein in the form of salts: chloride, bicarbonate, acetate. Acetate is necessary to prevent the development of acidosis; when it enters the body, bicarbonate is formed from it.

Magnesium is involved in the creation of muscle cells and bone structure. It is excreted from the body in large quantities in the urine, so it is important to calculate diuresis when replenishing it and take into account renal blood flow. Magnesium deficiency develops with alcoholism, exhaustion, pathology of the parathyroid glands, and taking aminoglycosides due to the increased excretion of magnesium in the urine against its background. In case of severe deficiency, it is administered intravenously in solutions, since hypomagnesemia causes a reduced calcium level in the blood.

Calcium is also included in the mixture, especially in sepsis and trauma, when increased calcium loss occurs. The calcium contained in the bones is consumed, and a decrease occurs with hypovitaminosis D. This also occurs with hypoalbuminemia, since calcium is associated with this protein fraction (approximately 50-60%).

Phosphates are present in red blood cells, are part of amino acids, phosphate proteins and lipids, and participate in metabolic processes in bone tissue. With severe pathology and prolonged fasting, exhaustion develops, which leads to hypophosphatemia. Parenteral nutrition enhances this process, since glucose, as in the case of potassium, transfers phosphorus from the extracellular fluid into the cell.

Vitamins

Vitamin preparations A, D, E in their water-soluble form, group B, ascorbic acid, folic acid, biotin are added to PP. They are used in dosages that significantly exceed the daily requirement indicated in the instructions. Vitamin K is administered once every 7-10 days, except for those patients who are prescribed anticoagulants. A hemodialysis patient should receive folic acid- is added without fail, since it is washed out after the procedure. When he is transferred to enteral nutrition, he receives multivitamins in tablets.

Microelements

Essential micronutrients (chromium, manganese, copper, selenium and zinc) are added to the intravenous nutritional formula daily.

Heparin

Heparin is added to improve the patency of veins and catheters at a dose of 1000 units per 1 liter of solution.

Albumen

Albumin is used for severe protein deficiency (if its content in the serum< 2,0 г/л).

Insulin

There is no need to use insulin in patients with unimpaired carbohydrate metabolism. It is needed for diagnosed diabetes.

Parenteral nutrition program for pancreatitis

PP is used in resuscitation for oncological neoplasms of the pancreas, after surgical operations.

Purpose protein nutrition, fats and carbohydrates are made by a nutritionist who determines:

• caloric intake;
• compound;
• daily amount of essential nutrients.

Parenteral nutrition does not enhance production, thereby creating functional rest for the organ. Therefore, PN is included in the complex therapy of pancreatitis, which begins immediately after the restoration of homeostasis and recovery from shock. Lipid emulsions increase the inflammatory process in the parenchyma of the gland and are contraindicated in acute pancreatitis.

Start of PP, amendments and termination

There is a basic protocol for nutritional support for patients with, which provides a detailed list of the necessary mixtures, their names, instructions for preparation for each of medicines and the amount that needs to be administered to patients depending on the severity and vital signs. Treatment in a hospital setting is carried out in accordance with the existing manual with methodological instructions, which contains a description of therapy using PN on a daily basis, depending on the identified pathology, duration of use of nutrient solutions, changes in their administration in doses and volume, and conditions for termination, according to homeostasis indicators. Also described modern technique PP, which is based on the principles:

• transfusion from various containers;
• all-in-one technologies.

The latter is developed in two versions:

• “two in one” - a two-chamber bag with glucose, electrolytes and amino acid preparations (Nutriflex);
• “three in one” - one bag contains all 3 components: carbohydrates, lipids, protein components (Kabiven): such a container has additional opportunity introduction of vitamins and microelements - this ensures a balanced composition of the mixture.

Monitoring the patient

After discharge from the hospital, the patient is observed at his place of residence. During this period he needs:

• organization of a rational diet;
• biochemistry monitoring.

Both the child and the adult must periodically undergo general medical checkup. In the event of a sharp deterioration of the condition, with the appearance of pain and high temperature It is recommended to call a doctor at home.

The patient stays for a long time:

• on hard according to Pevzner (fatty, spicy, fried, smoked foods are excluded; food is taken often and in small portions, warm);

Complications with parenteral nutrition

With PP, complications may develop:

• technical (vein rupture, embolism, pneumothorax);
• infectious (thrombosis in the catheter or infections in it, causing sepsis);
• metabolic (disorders of homeostasis due to improper administration of PP, leading to the occurrence of phlebitis, dysfunction respiratory system, liver);
• organopathological (early and late).

Early consequences appear:

• allergies;
• hyperhidrosis;
• shortness of breath;
• dizziness, severe weakness;
• hyperthermia;
• lumbar pain;
• inflammation at the injection site.

Late organopathological complications of PP are the result of improper use of fatty emulsions:

• cholestasis;
• hepatosplenomegaly;
• thrombocytopenia and leukopenia.

To avoid complications, before use, it is necessary to study the bottle or package with the dry drug, the release date, and other data, to clearly understand the pharmacology and compatibility of the prescribed mixtures, their ability to penetrate the histohematic barriers of the liver, lungs, and brain.

Only with careful observance of all indications and rules for the administration of PN, treatment is successful and the patient is gradually transferred to the usual regimen.

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

Nutritional support– a set of therapeutic measures aimed at identifying and correcting disturbances in the nutritional status of the body using nutritional therapy methods (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 a doctor to provide food to a patient should be regarded as a decision to starve him to death. A decision for which in most cases it would be difficult to justify,” wrote Arvid Vretlind.

Timely and adequate nutritional support can significantly reduce the incidence of infectious complications and mortality of 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 met artificially, or partial, if the introduction of nutrients by the enteral and parenteral routes is additional to the usual (oral) nutrition.

Indications for artificial nutritional support are varied. In general, they can be described as any disease in which the patient’s need for nutrients cannot be met naturally. Usually these are diseases of the gastrointestinal tract that 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 “7 days or 7% reduction in body weight” rule is widely known. It means that artificial nutrition must be carried out in cases where the patient has been unable to eat naturally for 7 days or more, or if the patient has lost more than 7% of the recommended body weight.

Assessing the effectiveness of nutritional support includes the following indicators: dynamics of nutritional status parameters; state of nitrogen balance; course of the underlying disease, 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 body's primary reaction in response to the cessation of the supply of nutrients from the outside is the use of glycogen and glycogen stores as an energy source (glycogenolysis). However, the glycogen reserve in the body is usually not large and is depleted within the first two to three days. In the future, the body's structural proteins (gluconeogenesis) become the easiest and most accessible source of energy. During the process of gluconeogenesis, glucose-dependent tissues produce ketone bodies, which, through a feedback reaction, slow down the basal metabolism and the oxidation of lipid reserves as an energy source begins. Gradually, the body switches to a protein-saving mode of functioning, and gluconeogenesis resumes only when fat reserves are completely depleted. So, if in the first days of fasting protein loss is 10–12 g per day, then in the fourth week it is only 3-4 g in the absence of pronounced external stress.

  In patients in critical condition, there is a powerful release of stress hormones - catecholamines, glucagon, which have a pronounced catabolic effect. In this case, the production is disrupted or the response to hormones with an anabolic effect such as growth hormone and insulin is blocked. As often happens 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. Catecholaminemia slows down the body's transition to using fat as an energy source. In this case (with severe fever, polytrauma, burns), up to 300 g of structural protein per day can be burned. This condition was called autocaniballism. Energy consumption increases 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 conditions is that in the first case there is an adaptive decrease in energy requirements, and in the second, energy consumption increases significantly. Therefore, in post-aggression 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 critical illness

    In critical illnesses, conditions often arise in which adequate perfusion and oxygenation of the gastrointestinal tract are disrupted. This leads to damage to intestinal epithelial cells with disruption of barrier function. The problems get worse if long time there are no nutrients in the lumen of the gastrointestinal tract (during fasting), since the cells of the mucous membrane receive nutrition to a large extent directly from the chyme.

    An important factor damaging the digestive tract is any centralization of blood circulation. With centralization of blood circulation, perfusion of the intestine and parenchymal organs decreases. In critical conditions, this is further aggravated by the frequent use of adrenomimetic drugs to maintain systemic hemodynamics. In terms of 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 disrupts the supply of antioxidants and their precursors to enterocytes and aggravates reperfusion injuries. The liver, due to autoregulatory mechanisms, suffers somewhat less from a decrease in blood flow, but its perfusion still decreases.

    During fasting, 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 quantities. Bacteria penetrating into 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 Kupffer cells of the liver. The stable balance is disrupted with uncontrolled growth of intestinal microflora and changes in its normal composition(i.e. with the development of dysbacteriosis), impaired mucosal permeability, impaired local intestinal immunity. It has been proven that microbial translocation occurs in critically ill patients. It intensifies in the presence of risk factors (burns and severe trauma, systemic antibiotics wide range, pancreatitis, hemorrhagic shock, reperfusion injuries, exclusion of solid foods, 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. This is 2 million people, 580 thousand deaths and treatment costs of about 4.5 billion dollars.

    Disorders of the intestinal barrier function, expressed in mucosal atrophy and impaired permeability, develop quite early in critically ill patients and are expressed already on the 4th day of fasting. Many studies have shown the beneficial effect of early enteral nutrition (the 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 maintain the immune system of the whole body in a normal state.

• Principles of nutritional support

  One of the founders of the doctrine of artificial nutrition, Arvid Wretlind (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. You cannot wait for the development of protein-energy malnutrition, since cachexia is much easier to prevent than to treat.

  • Optimality.

    Artificial nutrition must be carried out until the nutritional status stabilizes.

  • Adequacy.

    Nutrition must cover the body's energy needs and be balanced in the composition of nutrients and meet the patient's needs for them.

• Enteral nutrition

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

  Enteral nutrition is a type of artificial nutrition and, therefore, is not carried out through natural routes. To carry out enteral nutrition, one or another access is required, as well as special devices for administering nutritional mixtures.

  Some authors consider enteral nutrition only methods that bypass oral cavity. Others include oral feeding 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” (sip feeding) - oral administration of a special mixture for enteral nutrition in small sips (usually through a tube).

  • Benefits of Enteral Nutrition

    Enteral nutrition has a number of advantages over parenteral nutrition:

    • Enteral nutrition is more physiological.
    • Enteral nutrition is more economical.
    • Enteral nutrition practically does not cause life-threatening complications and does not require strict sterility.
    • 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 when 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 to use enteral nutrition in all cases where this is possible, if only because its cost is significantly lower than parenteral nutrition, and its effectiveness 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 and 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 organizing enteral nutrition..." the Ministry of Health of the Russian Federation identifies the following nosological indications for the use of enteral nutrition:

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

    Enteral nutrition is a technique that is being intensively studied and used in an increasingly diverse group of patients. Stereotypes are being broken about mandatory fasting in patients undergoing operations on the gastrointestinal tract, in patients immediately after recovery from 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 to provide enteral nutrition.
    • Continued gastrointestinal bleeding.

    Relative contraindications to enteral nutrition:

    • Partial intestinal obstruction.
    • Severe intractable diarrhea.
    • External small intestinal fistulas with discharge 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 with a distal tube position 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 (feces) in the intestines (essentially intestinal paresis).
  • General recommendations for enteral nutrition
    • Enteral nutrition should be given as early as possible. Provide 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 value 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 feed the patient adequately, then a probe should be inserted into the ileum in a blind manner (endoscopically or under X-ray control).
    • It should be conveyed to the nurse providing enteral nutrition that if she cannot provide it properly, 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 is provided that in patients with multiple injuries, enteral nutrition was started immediately after stabilization of the condition, in the first 6 hours from admission. Compared to the control group, when nutrition began after 24 hours from admission, a less pronounced disturbance of the permeability of the intestinal wall and less pronounced multiple organ disorders were noted.

    In many resuscitation centers, the following tactics have been adopted: enteral nutrition should begin as early as possible - not only in order to immediately replenish the patient’s energy costs, but in order to prevent changes in the intestines, which can be achieved by enteral nutrition with relatively small volumes of administered food .

    Theoretical basis for early enteral nutrition.

    Lack of enteral nutrition leads to:
    Atrophy of the mucous membrane.	Proven in animal experiments.
    Excessive colonization of the small intestine.	Enteral nutrition prevents this in the experiment.
    Translocation of bacteria and endotoxins into the portal bloodstream.	People have impaired mucosal permeability due to burns, trauma, and critical conditions.

  • Enteral nutrition regimens

    The choice of diet is determined by the patient’s condition, 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.

    The following modes of enteral nutrition are available:

    • Power supply at constant speed.

      Feeding through a gastric tube begins with isotonic mixtures at a rate of 40–60 ml/hour. If well tolerated, the feeding rate can be increased by 25 ml/hour every 8–12 hours until the desired rate is achieved. 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.

      In case of nausea, vomiting, cramps or diarrhea, it is necessary to reduce the rate of administration or the concentration of the solution. In this case, simultaneous changes in the feeding rate and concentration of the nutrient mixture should be avoided.

    • Cyclical nutrition.

      The continuous drip is gradually “compressed” to a 10–12 hour overnight period. Such nutrition, convenient for the patient, can be provided through a gastrostomy tube.

    • Periodic or session nutrition.

      Nutrition sessions of 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 imitates a normal meal, therefore ensuring a more natural functioning of the gastrointestinal tract. It is performed only with transgastric access. The mixture is administered dropwise or by syringe at a rate of no more than 240 ml in 30 minutes 3-5 times a day. The initial bolus should not exceed 100 ml. If well tolerated, the injected volume is increased daily by 50 ml. Diarrhea develops more often during bolus feeding.

    • Usually, if the patient has not received nutrition for several days, continuous drip administration of mixtures is preferable to periodic administration. 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 formula for enteral nutrition depends on many factors: the disease and general condition of the patient, the presence of disorders of the patient’s digestive tract, and the required enteral nutrition regimen.

    • General requirements requirements for enteral formulas.
      • The enteral mixture must have sufficient energy density (at least 1 kcal/ml).
      • Enteral formula should be lactose and gluten free.
      • The enteral mixture should have low osmolarity (no more than 300–340 mOsm/L).
      • The enteral mixture should have a low viscosity.
      • Enteral formula should not cause excessive stimulation of intestinal motility.
      • The enteral formula must contain sufficient information about the composition and manufacturer of the nutritional formula, as well as indications of the presence of genetic modification of nutrients (proteins).

    None of the mixtures for complete EN contain sufficient free water to meet the patient's daily fluid requirements. The daily fluid requirement is usually estimated as 1 ml per 1 kcal. Most formulas 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 nutrition.

    Currently, formulas 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 incidence of complications of enteral nutrition.

    • Enteral nutrition is carried out in severe 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

      The following types of complications of enteral nutrition are distinguished:

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

      This classification does not include complications associated with enteral nutrition techniques - self-extraction, migration and blockage of feeding tubes and feeding 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 no uniform diagnostic criteria to determine a particular complication and there is no uniform protocol for managing complications.

      • High residual volumes - 25%-39%.
      • Constipation - 15.7%. With long-term enteral nutrition, the incidence of constipation can increase 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 different authors, the frequency of aspiration pneumonia is indicated from 1 to 70 percent.
  • About sterility during 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 proliferation of microorganisms and, on the other hand, in the departments intensive care there are all conditions for bacterial aggression. The danger is represented by both the possibility of infection of the patient with microorganisms from the nutritional 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. Other factors accompanying the development of infection include: antibacterial therapy, immunosuppression, concomitant infectious complications, etc.

    Common recommendations to prevent bacterial contamination are to use no more than 500 ml of locally prepared mixture. 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, and droppers. It seems reasonable that for IVs 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 to replenish energy, plastic costs and maintain normal level metabolic processes are introduced into the body, bypassing 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 functioning that are 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 selectively replenishing the deficiency of those ingredients, the supply or absorption of which is not ensured by the enteral route. Incomplete parenteral nutrition is considered as additional nutrition if it is used in combination with tube or oral administration of nutrients.

    • Mixed artificial nutrition.

      Mixed artificial nutrition is a combination of enteral and parenteral nutrition in cases where none of them is predominant.

  • Main objectives 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 necessary vitamins, macro- and microelements.
  • Parenteral Nutrition Concepts

    Two main concepts of PP have been developed.

    1. The “American concept” - the hyperalimentation system according to S. Dudrick (1966) - involves the separate introduction of solutions of carbohydrates with electrolytes and nitrogen sources.
    2. The “European concept”, created by A. Wretlind (1957), involves the separate introduction of plastic, carbohydrate and fatty 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, many countries have begun to use the all-in-one parenteral nutrition technique, using 3-liter containers to mix all the ingredients in one plastic bag. If it is impossible to mix three-in-one solutions, infusion of plastic and energetic 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 manipulation of containers containing nutrients, their contamination is reduced, and the risk of hypoglycemia and hyperosmolar non-ketone coma is reduced. Disadvantages: sticking of fatty particles and the 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 stored in the refrigerator.

  • Basic principles of parenteral nutrition
    • Timely initiation of parenteral nutrition.
    • Optimal timing of parenteral nutrition (until restoration of normal trophic status).
    • Adequacy (balance) of parenteral nutrition in terms of the amount of nutrients introduced and the degree of their absorption.
  • Rules for parenteral nutrition
    • Nutrients must be administered in a form adequate to the metabolic needs of the cells, that is, similar to the entry of nutrients into the bloodstream after passing 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 energetic substrates must be introduced simultaneously. Be sure to use all 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 conducting a complete PN, the inclusion of glucose concentrates in the mixture is mandatory.
    • The fluid requirement for a stable patient is 1 ml/kcal or 30 ml/kg 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 conditions of cessation or limitation of the supply of nutrients by exogenous routes, the most important adaptive mechanism comes into play: the consumption of mobile reserves of carbohydrates, body fats and the intensive breakdown of protein into amino acids with their subsequent conversion into carbohydrates. Such metabolic activity, although initially expedient and 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 body’s needs not through the breakdown of its own tissues, but through 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 a loss of 94-200 g of tissue protein or 375-800 g of muscle tissue.

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

    • Inability to take oral or enteral food 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 dysfunction of the gastrointestinal tract).
    • Severe hypermetabolism or significant protein loss, when enteral nutrition alone does not cope with nutrient deficiency (a classic example is burn disease).
    • The need to temporarily exclude 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 increased 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 organ surgery abdominal cavity or its complicated course (anastomotic leakage, fistulas, peritonitis, sepsis).
      • In the post-traumatic period (severe burns, multiple injuries).
      • With increased protein breakdown or disruption of its synthesis (hyperthermia, failure of liver, kidney, etc.).
      • In intensive care patients, when the patient does not regain consciousness for a long time or the activity of the gastrointestinal tract is sharply disrupted (damage to the central nervous system, tetanus, acute poisoning, comatose states, etc.).
      • At infectious diseases(cholera, dysentery).
      • For neuropsychiatric diseases in cases of anorexia, vomiting, food refusal.
  • Contraindications to parenteral nutrition
    • Absolute contraindications to PN
      • 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, elements of PN can be used during 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 are determined by pathological changes in the body caused by the underlying and concomitant diseases.

      • In case of liver or kidney failure, amino acid mixtures and fat emulsions are contraindicated.
      • In case of 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 cases of violation of the coagulating properties of blood, fat emulsions are contraindicated.
      • Caution must be exercised in patients with allergic diseases.
  • Providing 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 recanalized umbilical vein; through shunts; intra-arterially.

      When carrying out parenteral nutrition, infusion pumps and electronic drop regulators are used. The infusion should be carried out over 24 hours at a certain speed, 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 used:

      • Via 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 central vein using temporary central catheters. Among the central veins, preference is given to the subclavian vein. Less commonly used are the internal jugular and femoral veins.
      • Through the central vein using indwelling central catheters.
      • Through alternative vascular accesses and extravascular accesses (for example, the peritoneal cavity).
  • Parenteral nutrition regimens
    • 24-hour administration of nutrient media.
    • Extended infusion (over 18–20 hours).
    • Cyclic mode (infusion over 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:

      • Have a nutritional effect, that is, contain all the substances necessary for the body in sufficient quantities and in proper proportions to each other.
      • Replenish the body with fluid, as many conditions are accompanied by dehydration.
      • It is highly desirable that the products used have a detoxifying and stimulating effect.
      • It is desirable to have a substitutive and anti-shock effect of the drugs used.
      • It is necessary to ensure that the products used are harmless.
      • An important component is ease of use.
    • Characteristics of parenteral nutrition products

      To correctly use nutrient solutions for parenteral nutrition, it is necessary to evaluate some of their characteristics:

      • Osmolarity of solutions for parenteral nutrition.
      • Energy value of solutions.
      • The limits of maximum infusions are the rate or rate of infusion.
      • When planning parenteral nutrition, the required doses of energy substrates, minerals and vitamins are calculated based on their daily needs and level of energy consumption.
    • Parenteral nutrition components

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

      • Carbohydrates and alcohols are the main sources of energy during parenteral nutrition.
      • Sorbitol (20%) and xylitol are used as additional energy sources with glucose and fat emulsions.
      • Fats are the most effective energy substrate. They are administered in the form of fat emulsions.
      • Proteins are the most important integral part for the construction of tissues, blood, synthesis of proteohormones, enzymes.
      • Saline solutions: simple and complex, are introduced to normalize water-electrolyte and acid-base balance.
      • Vitamins, microelements, and anabolic hormones are also included in the parenteral nutrition complex.
    More details: Pharmacological group- Means for parenteral nutrition.
  • Assessing the patient's condition if parenteral nutrition is necessary

    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.

    • Nutrition assessment and monitoring of parenteral nutrition adequacy.

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

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

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

        Serum albumin. When it decreases below 35 g/l, the number of complications increases 4 times, mortality increases 6 times.

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

        Excretion of creatinine, urea, 3-methylhistidine (3-MG) in urine. A decrease in creatinine and 3-MG excreted in urine indicates a muscle protein deficiency. 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).

        Controlling the concentration of glucose in the blood and urine: the appearance of sugar in the urine and an increase in the concentration of glucose in the blood more than 2 g/l requires not so much an increase in the dose of insulin as a decrease in the amount of administered glucose.

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

    Parameters for monitoring homeostasis during complete PN were defined 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, arterial pressure and respiratory rate are determined in patients daily. Determination of basic laboratory parameters in unstable patients is usually carried out 1–3 times a day, with nutrition in the pre- and postoperative period 1–3 times a week, with long-term PN - 1 time a 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 enteral nutrition is impossible (intestinal fistulas with significant discharge, short bowel syndrome or malabsorption, intestinal obstruction, etc.).

    Parenteral nutrition is several times more expensive than enteral nutrition. When carrying out it, strict adherence to sterility and speed of introduction of ingredients is required, which is associated with certain technical difficulties. Parenteral nutrition produces a fair number of complications. There are indications that parenteral nutrition may suppress one's own immunity.

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

    Enteral nutrition is more physiological. It does not require sterility. Enteral nutrition mixtures contain all the necessary components. Calculation of the need for enteral nutrition and the methodology for its implementation are much simpler than for parenteral nutrition. Enteral nutrition allows you to maintain the gastrointestinal tract in a normal physiological state and prevent many complications that arise in patients in critical condition. 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 favor enteral nutrition.