Currently, the state of the art of parenteral nutrition is providing individualized prescription of nutrients for each patient every day. This is accomplished using automated equipment that combines amino acids, dextrose, lipids, electrolytes, vitamins and trace elements in a specific formula. The chemicals are properly trained in the capacity to provide electrolytes in parenteral nutrition at levels sufficient to replace ongoing losses or to meet the increased needs. This reduces interruptions in the infusion, minimizes the risk of infection and saves time for care. A number of drugs but limited, such as insulin and H2 receptor antagonists of histamine, can be added to total parenteral nutrition.

At present, there are numerous guides to select patients for parenteral nutrition. The following table is a summary of these guidelines. Each of these assumes that the patient's gastrointestinal tract is not functional. In addition the patient must be at nutritional risk defined as the loss of more than 10% of premorbid weight requirement or nothing by mouth for more than five to seven days.

Guidelines for Parenteral Nutrition

• Parenteral nutrition is unlikely to benefit patients whose malignant disease does not respond to chemotherapy or radiotherapy.
  
  
• The total parenteral nutrition may be beneficial for those cancer patients whose treatment is expected to produce gastrointestinal toxicity preventing oral intake for more than a week.

Perioperative period

• The preoperative total parenteral nutrition is no longer so widely used unless patients are severely malnourished or are expected and not allowed orally for more than seven to ten days.

Inflammatory bowel disease

• Useful in the presence of high-flow fistulas.
  
  
• Can the remission in 60% to 80% of acute illnesses.
  
  
• No influence on disease activity in acute exacerbations of ulcerative colitis.

Renal Disease

• Total parenteral nutrition is useful in renal failure.
  
  
• The amino acid solutions containing only essential amino acids are no longer recommended.

Hepatic dysfunction

• Parenteral nutrition is recommended for patients with nutritional compromise with advanced chronic liver failure.
  
  
• Formulas with branched chain amino acids are used only when conventional therapy with lactose and neomycin does not prevent or reduce hepatic encephalopathy.

Pancreatitis

• The total parenteral nutrition may be preferred to avoid pancreatic stimulation or when there is an increased flow fistulas.
  
  
• The lipid emulsions are safe in pancreatitis but is recommended to keep triglycerides below 400 mg / dl.

Intensive Care

• Total parenteral nutrition is indicated if the hypermetabolic phase is estimated to last more than 4 to 5 days.
  
  
• The branched-chain amino acids have shown no benefit.

S.I.D.A.

• The use of total parenteral nutrition should be very careful because of the high risk of infection.

Short bowel syndrome

• May be required indefinitely when there is less than 60 cm of small intestine.

Respiratory syndrome

• The handling of the relationship of carbohydrate-lipids can reduce CO2 production but probably not alter the respiratory quotient or benefit patients who are not hypernutrition.
  
  
• Parenteral lipids should be administered carefully in patients with severe defects in oxygenation.

Eating disorders

• The total parenteral nutrition may be useful in patients with eating disorders with severe malnutrition who can not stand the enteral nutrition for physical and emotional.
  
  
• Is indicated gradual onset of total parenteral nutrition-risk due to complications.
  
  
• Parenteral nutrition is safe in pregnancy.
  
  
• Total parenteral nutrition is recommended in patients with neurological problems.
  
  
• Total parenteral nutrition is useful in intestinal pseudo.

Adherence to these guidelines will undoubtedly improved patient care and cost savings in institutions where total parenteral nutrition has been overused.

The role of clinical nutritional support parenteral nutrition is to promote a safe and effective way to reduce the cost conscious as possible. Clinicians working with patients, physicians and administrators in order to balance the technology and costs in order to provide a status of total parenteral nutrition.

Composition of parenteral nutrition

Intravenous feeding competence should contain protein (as amino acids), carbohydrates, lipids, vitamins, electrolytes, minerals and water charm, quality and proportion similar to those given by the gastrointestinal tract.

• Carbohydrates.
  
  All human cells have the ability to oxidize glucose, and this has been used widely in parenteral nutrition and is today the main source of energy. The energy requirements of a normal person is given 60% glucose, 30% as fat and 10% as protein.
  
  Have been used other caloric sources different from glucose, fat and protein in parenteral nutrition. Those that have been tested are fructose, maltose, sorbitol, xylitol, glycerol and ethanol.

• Fat emulsions.
  
  Fats for parenteral administration currently in use have the following characteristics:
  
  Emulsion is the mixture of lipids and water in which the lipid particles remain dispersed in the aqueous emulsifying agents, such as polar lipids, which form a surface layer that separates the main mass of non-polar aqueous phase and keep them stable and dispersed.
  
  The emulsifier used in all the preparations in use is the lecithin in egg yolk. Employees fatty acids are extracted and purified vegetable oils and are mainly long-chain fatty acids, linoleic, linolenic, oleic and palmitic medium chain mainly capric, lauric and caproic. The Intralipid and Liposyn contain long chain fatty acids and Lipofundin contains medium chain fatty acids (50%) and long chain (50%)
  
  The instability of the emulsion is characterized by flocculation or aggregation of fat particles making them larger. These particles migrate to the surface of the emulsion and form a layer of brown fat.
  
  This instability occurs in the presence of increasing ionic strength given by monovalent cations, but especially divalent cations like Ca and Mg, and trivalent Cr and as an acid pH (<5.5). Thus, the addition of large amounts of divalent cations or acidic solutions may break the emulsion. Lipids should be added at the end, after the mixture of amino acids and dextrose which buffers the acidic pH of dextrose. 3 in 1 mixes packaged in PVC bags after 24 hours release toxic plasticizers in the walls of the bags. 24 hours before its use is safe. EVA bags do not exhibit this problem. 3 in 1 bags should be refrigerated at 4 C when being prepared.
  
  Instructions. Lipid emulsions can be administered by low osmolarity peripheral or central route. Is given alone or in combination with amino acids and dextrose mixtures 3 calls 1. They should not add any medication to the bottle of emulsion by the possibility of physical instability disorders. The intermittent administration is preferable to the continuous use since the immune system involvement is higher in continuous infusions.

• Amino Acids.
  
  The standard amino acid mixtures has been developed trying to mimic the composition of proteins of high biological level. Some requirements for the development of amino acid solutions for parenteral nutrition are:

• Contain all the essential amino acids and preferably all non-essential.
  
  Contain the right proportions of amino acids.

• There should be inbalances, antagonism, or toxicity.
  
  Contain additives (sodium acetate, potassium or magnesium) to adjust pH.

• May or may not contain electrolytes.

How to use:

• May be given alone or in combination with glucose and lipids.
  
  
• You can add electrolytes, vitamins and drugs in accordance with established standards.
  
  
• May be infused by central or peripheral venous line.

Minerals and vitamins *

The substitution of minerals, electrolytes and water in parenteral nutrition is an individual problem that can be the substitution of amino acids, carbohydrates and fats. The requirements of these nutrients must be established according to general, but depend on the exact dosage and serum determinations of estimated losses from fistulas, secretions, urine, etc.., And the evaluation of the particular pathology, the degree stress and nutritional status.

By definition, vitamins are vital and must be included when considering the full intravenous feeding.

Dietary components are essential for growth, maintenance and normal body functions. These nutrients act as enzymatic cofactors in a wide variety of vital metabolic pathways, since use of energy, protein synthesis, maintenance of the host defense, wound healing, and so on.

In cases where parenteral nutrition is indicated partial substitution of vitamins is subject to specific requirements according to pathology.

The parenteral vitamin therapy in artificial nutrition is still uncertain because there is a general concept regarding accurate dosing. However, in certain diseases such as cancer, extensive burns and sepsis need extra doses of certain vitamins essential for healing and amino acid transport

Therefore, vitamins should be included in any system of artificial nutrition in adequate amounts to avoid signs of deficiency.

Vascular access for parenteral nutrition

Parenteral nutrition can be administered by peripheral veins or at the level of the pit, near the mouth of the right atrium. The choice of one route or another, depends on several factors:

• Chemical Factors
  
  Iso-osmolar solutions, hypoosmolar or slightly hyperosmolar relative to plasma can be given by peripheral veins. However, in most cases nutrient solutions are hyperosmolar and to bring them into contact with the vessel walls occurs endothelial injury, thrombosis, phlebitis and therefore they must be infused into the cellar where high flow dilutes its hyperosmolarity.
  
  The additives and components of these solutions can, regardless of the osmolarity, injure the endothelium and these factors must be taken into account in choosing the route of administration.

• Physical factors.
  
  The characteristics of the catheters and cannulas will be reviewed later. Despite the progress of design and development of new materials using peripheral cannulas or catheters that access the central circulation through peripheral venipuncture, leading to thrombophlebitis in a short time, 3 to 5 days, which prevents higher frequency the use of the peripheral route. Good results have been reported in the peripheral route, with the use of silicone catheters

• Duration of cannulation.
  
  Parenteral nutrition therapy is a medium to long term, 8 to 10 days at least. This facilitates the development of phlebitis when using peripheral venous circulation. Central access, by contrast, allows prolonged use without complications.

• Experience of the operator in central cannulation.
  
  For any access the physician should ascertain the chemical characteristics of the solutions and additives, and the characteristics of the catheters. If you chose the peripheral route should follow the rules to reduce infectious complications. The parenteral solution administration via peripheral responsibility in all aspects of nutritional support group.

Piggyback method for parenteral nutrition

Is to take an intermittent intravenous drip of a second solution, the reconstituted active on the site of a primary IV set. This can be seen that the P.A. or nutrient vein enters the "set" in the primary IV fluid. This technique eliminates the need for punching another vein, but also gets the dilution of PA peak blood levels are reached in a relatively short time, usually 30 to 60 minutes. The dilution of the PA helps to reduce irritation.

Parenteral Dosage in hospital pharmacy

To maintain the characteristics of sterile products is essential to be handled in an aseptic environment, using appropriate techniques.

• ENVIRONMENT. There must be clean or aseptic areas, environmental and physical controls similar to those used in the manufacture of IV solutions, this means: Class 100, injection rate of 30 meters per minute, HEPA filters, humidity control.

• PERSONAL. Is required to have highly trained pharmacists in hospital pharmacy (dosing and process control). Strict sanitary controls of staff.

• PROCESSES. Validation of the processes involved in dosing and monitoring of IV.

• DOCUMENTATION. There must be documentary evidence to ensure the reliability of processes.

Standards for the preparation of mixtures

• Check the prescribed formula and make sure that all elements are at hand.
  
  
• Register on the label of the solutions the following information

Patient's name.

Room Number

Concentration and amount of dextrose

Concentration and amount of amino acids and specifying whether or not it comes with electrolytes

Total amount of the mixture in milliliters

Signature of person preparing the mix and date

If there is a particular concentration of electrolytes, specify in a notice apart.

• Prepare the elements for the preparation of the mixture on the table chosen.

• Clean with Betadine caps of bottles and the necks of the vials before opening.
  
  
• Upon verification with the formula, add to the bag or bottle ordered substances, following the manufacturers instructions for handling these bags or bottles.
  
  
• Follow an order adding the substance as follows: first container dextrose, amino acids and then finally lipids. After the addition of each substance shake the solution. Dispose of syringes, vials and ampoules that have been used.
  
  
• The cocks should be closed at the beginning of the catheters and should be doing two knots to the catheter near the key, cutting with sterile scissors extra line.
  
  
• Dispose of empty bags.
  
  
• If there was contamination of the bag or jar with mixture solutions, using a sterile gauze soaked in water to clean and dry the bag also with sterile gauze.
  
  
• Place the appropriate label.
  
  
• Place the bag of TPN also labeled on the box labeled with the patient's room number.
  
  
• The prepared solutions should be stored in their boxes, preferably in cold room (4 ° C) until use.
  
  
• At the end of preparation, clean the area of preparation.

Management of parenteral nutrition solutions to prevent contamination

Parenteral nutrition solutions are excellent culture media and therefore must take extreme caution in handling to avoid cross-contamination and compromise the patient's health. The most important factors to be taken into account in controlling the contamination of parenteral nutrition mixtures are:

• Ambient Air Quality.
• Teams
• Staff
• Packaging

The primary source of microbial contamination in any environment is ultimately controlled personnel working in them. Employees engaged in the preparation of parenteral nutrition, nurse or a pharmacist, must receive prior training to prepare and manage parenteral nutrition mixtures.

To prepare the technician must register Clothing designed for this purpose that includes a hat, boots, clothing and face mask. After hand washing with soap is placed using sterile gloves during the preparation process. This dress can not be used outside the sterile area.

Will pharyngeal and stool cultures technicians on a regular and annual medical checkup to rule out infectious disease that could be the source of contamination in their work.

Parenteral nutrition solutions can become contaminated:

• During storage
• During the preparation
• During the administration to the patient

Solutions are discarded

• Having fulfilled due date
• That are outside their sealed containers
• What are cloudy or have foreign material, precipitates, etc..
• With the lids open
• Outdated or broken bottles

Are discarded bottles with parenteral nutrition:

• When worn over 24 hours.
  
  
• When removal has been discontinued and a solution. Use a new solution.
  
  
• When the solution has been dampened extravasation and healing in the area of the catheter, it is healing and change IV tubing.
  
  
• When the solution or the IV tubing is contaminated with pus or contaminated materials, the solution is discarded and the infusion tubing.
  
  
• If you suspect infection, the patient signs and symptoms (fever, chills, shock exit of pus at the site of catheter insertion, erythema in this area, tachycardia, lethargy) and laboratory (WBC, elevated ESR, hyperglycemia not related to sudden changes in the rate of infusion of the solution, jaundice).

Parenteral incompatibility

When combined with one or more PA IV fluid, the presence of all of them can change the intrinsic characteristics of the PA present and cause an incompatibility parenterally. These are classified into three:

• THERAPEUTIC. These are the most difficult to observe because the combination creates an antagonistic or synergistic pharmacological activity undesirable.
  
  
• PHYSICAL. These are the most easily observed and detected by changes in the appearance of a mixture, a color change, formation of a precipitate or gas evolution. The physical incompatibilities often be predicted by knowing the chemical characteristics of the PA participants.
  
  
• CHEMICAL. A breakdown of PA by a combination of parenteral dosage forms is called chemical incompatibility, although this classification is arbitrary, and that chemical changes produce physical changes. Most of these inconsistencies are due to hydrolysis, oxidation, reduction, or complexation, and only can be detected with analytical methods.

An important factor that causes incompatibility is a change in acid-base environment. As the pH of the solution is changed, the effect can alter the stability of a PA The change in pH of a solution can alert to a mismatch, especially one that affects the stability of the PA, because this is not evident in all cases.