Nutrition parenteral

Parenteral nutrition (PN) provides macro- and micronutrients by central or peripheral venous access to meet specific nutritional requirements of the patient, promote positive clinical outcomes, and improve quality of life. PN is also referred to as total parenteral nutrition or hyperalimentation. 

Identifying candidates and deciding when to initiate PN are difficult decisions because data are conflicting, and published guidelines are not consistent. 

In general, PN should be considered when a patient cannot meet nutritional requirements through use of the GI tract. Consensus guidelines are based on clinical experience and investigations in specific populations 

PN should be considered after suboptimal nutritional intake for 1 day in preterm infants, 2 to 3 days in term infants, 5 to 7 days in well-nourished children, and 7 to 14 days in older children and adults. The route and type of PN depend on the patient s clinical state and expected length of PN 

Optimal nutrition therapy requires defining the patient s nutrition goals, determining the nutrient requirements to achieve those goals, delivering the required nutrients, and assessing the nutrition regimen. 

Hospital patients are becoming increasingly dependent upon nutrition being administered through a vein rather than through the oral route. Currently, some 5% of patients are totally dependent upon parenteral nutrition, sometimes for short-term support whilst they recover consciousness from an intestinal operation, but in the extreme, patients have been returned to a fairly active life totally supported by this means for more than ten years. 

Essentially, all of the requirements for the normal diet such as water, energy sources (amino acids, glucose, protein, phospholipid, and glycerol), nitrogen source (amino acids), minerals (electrolytes, trace elements), vitamins, and even the occasional drug, such as an anticoagulant, have to be mixed into a fluid to be passed into a vein. 

Often the condition leading to the requirement for parenteral nutrition has seriously depleted the trace element stores of the patient concerned and so it is vitally important that adequate amounts of trace elements are present in parenteral nutrition fluids. 

Premature infants are another critical group they often require to be kept on parenteral nutrition for up to three months until they have matured sufficiently to be able to suckle and take in more normal nutrition. 

Particular problems arise from the administration of the electrolytes and trace elements used to ensure that the intravenous fluid is completely isotonic and compatible with the plasma. Such charged species can cause flocculation or even coalescence of the oil-water emulsion. 

Intravenous feeding involves many problems, some of which remain to be solved. The basic problem is the compounding of utilizable nutrients which can be dispersed in a suitable medium and administered without greatly disturbing the fluid distribution, acid-base balance, or metabolic status of the body. Because a major need in intravenous feeding is the provision of suitable energy-yielding food, carbohydrates are important. 

Owing to the high osmotic pressure of hexose solutions in comparison to that of equivalent amounts of carbohydrate as water-soluble polysac- 

Strong evidence is available that the post-eruptive period may be divided into an early period of indefinite length, but perhaps lasting many years, during which the newly exposed surfaces mature. Before complete maturation, the teeth may be much more susceptible to attack and to exchange with components of saliva and blood than in the subsequent period. 

Carbohydrates, then, are of dental interest through any general metabolic effect that they may exert, this effect being primarily operative during the pre-emptive period of the tooth. Once the teeth are erupted, the 

Toverud, S. B. Finn, G. J. Cox, C. F. Bodecker, and J. H. Shaw, A Survey of the Literature of Dental Caries, Publ. 225, National Academy of Sciences, National Research Council, Washington, D. C., 1952. 

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Biomedical Uses. The molybdate ion is added to total parenteral nutrition protocols and appears to alleviate toxicity of some of the amino acid components in these preparations (see Mineral NUTRIENTS) (97). Molybdenum supplements have been shown to reduce iiitrosarnine-induced mammary carcinomas in rats (50). A number of studies have shown that certain heteropolymolybdates (98) and organometaUic molybdenum compounds (99) have antiviral, including anti-AIDS, and antitumor activity (see Antiviral agents Chemotherapeutics, anticancer). 

Impla.nta.ble Ports. The safest method of accessing the vascular system is by means of a vascular access device (VAD) or port. Older VAD designs protmded through the skin. The totally implanted ports are designed for convenience, near absence of infection, and ease of implantation. Ports allow dmgs and fluids to be deUvered directiy into the bloodstream without repeated insertion of needles into a vein. The primary recipients of totally implanted ports are patients receiving chemotherapy, bolus infusions of vesicants, parenteral nutrition, antibiotics, analgesics, and acquired immune disease syndrome (AIDS) medications. 

Manufacture of vitamin C starts with the conversion of sorbitol to L-sorbose. Sorbitol and xyHtol have been used for parenteral nutrition following severe injury, bums, or surgery (246). An iron—sorbitol—citric acid complex is an intramuscular bematinic (247). Mannitol administered intravenously (248) and isosorbide administered orally (249) are osmotic diuretics. Mannitol hexanitrate and isosorbide dinitrate are antianginal dmgs (see Cardiovascular agents). 

K. H. Bressler and K. Schultis, iu H. Ghadimi, ed.. Total Parenteral Nutrition Premises and Promises, John. Wiley Sons, Inc., New York, 1975, pp. 65-83. 

Alimentary biotin deficiency is rare. It may, however, occur in patients on long-term parenteral nutrition lacking biotin or in persons who frequently consume raw egg white. Raw egg white contains a biotin-binding glycoprotein, called avidin, which renders biotin biologically unavailable. Pharmacological doses of the vitamin (1-10 mg/d) are then used to treat deficiency symptoms. There are no reports of toxicity for daily oral doses up to 200 mg and daily intravenous doses of up to 20 mg [2]. 

Panthenol is frequently used in ointments and solutions for the treatment of burns, anal fissures, and inflammation of the conjunctiva. The vitamin has to be substituted in patients on total parenteral nutrition and in those who regularly undergo dialysis. Hypervitamin-osis has not been observed for doses up to 5 g/d (22). Furthermore, the administration of pantothenic acid leads to improved surgical wound healing due to its antiinflammatory properties. 

The composition of body fluids remains relatively constant despite the many demands placed on the body each day. On occasion, these demands cannot be met, and electrolytes and fluids must be given in an attempt to restore equilibrium. The solutions used in the management of body fluids discussed in this chapter include blood plasma, plasma protein fractions, protein substrates, energy substrates, plasma proteins, electrolytes, and miscellaneous replacement fluids. Electrolytes are electrically charged particles (ions) that are essential for normal cell function and are involved in various metabolic activities. This chapter discusses the use of electrolytes to replace one or more electrolytes that may be lost by the body. The last section of this chapter gives a brief overview of total parenteral nutrition (TPN). 

Along with a disturbance in fluid volume (eg, loss of plasma, blood, or water) or a need for providing parenteral nutrition with the previously discussed solutions, an electrolyte imbalance may exist. An electrolyte is an electrically charged substance essential to the normal functioning of all cells. Electrolytes circulate in the blood at specific levels where they are available for use when needed by the cells. An electrolyte imbalance occurs when the concentration of an electrolyte in the blood is either too high or too low. In some instances, an electrolyte imbalance may be present without an appreciable disturbance in fluid balance For example, a patient taking a diuretic is able to maintain fluid balance by an adequate oral intake of water, which... 

When normal enteral feeding in not possible or is inadequate to meet an individual s nutritional needs, intravenous (IV) nutritional therapy or total parenteral nutrition (TPN) is required. Products used to meet the IV nutritional requirements of the patient include protein substrates (amino acids), energy substrates (dextrose and fat emulsions), fluids, electrolytes, and trace minerals (see the Summary Drug Table Electrolytes). 

TPN may be administered through a peripheral vein or through a central venous catheter. Peripheral TPN is used for patients requiring parenteral nutrition for relatively short periods of time (no more than 5-14 days) and when the central venous route is not possible or necessary. Peripheral TPN is used when the patient s caloric needs are minimal and can be partially met by normal... 

Grego, AV and Mingrone, G. Dicarboxylic acids, an alternate fuel substrate in parenteral nutrition An update. Clin Nutr, 1995, 14, 143-148. 

Amino adds find apphcations as ingredients of infiision solutions for parenteral nutrition and individnally for treatment of specific conditions. They are obtained either by fermentation processes similar to those used for antibiotics or in cell-fiee extracts employing enzymes isolated fiom bacteria (Table 25.1). Details of the mar and varied... 

Principles of Parenteral Nutrition (Consult a Nutrition Expert Wherever Appropriate)... 

Patients who require parenteral nutrition for >7 d ° Must be administered through a central vein... 

When discontinuing parenteral nutrition, it is important to taper over several days to prevent hypoglycemia... 

If parenteral nutrition is stopped abruptly, replace with a dextrose 10% in water solution and infuse at the same parenteral nutrition rate... 

Concentrate intravenous medications ° Evaluate maintenance fluids ° Concentrate parenteral nutrition 0 Use concentrated enteral nutrition products Avoid and/or discontinue nephrotoxins wherever possible... 

Parenteral nutrition (amino acid salts) and arginine... 

No specific dietary restrictions are recommended for patients with IBD, but avoidance of high-residue foods in patients with strictures may help to prevent obstruction. Nutritional strategies in patients with long-standing IBD may include use of vitamin and mineral supplementation. Administration of vitamin B12, folic acid, fat-soluble vitamins, and iron may be needed to prevent or treat deficiencies. In severe cases, enteral or parenteral nutrition maybe needed to achieve adequate caloric intake. 

Adjunctive therapy with fluid and electrolyte replacement should be initiated. Nutritional support with enteral or parenteral nutrition may be indicated for patients unable to eat for more than 5 to 7 days.2 Some evidence suggests that enteral nutrition provides anti-inflammatory effects in patients with active CD.40,41... 

In rare instances (0.5% to 2% of pregnancies), NVP progresses to hyperemesis gravidarum.9 Treatment may require the use of enteral or parenteral nutrition if weight loss is present. A corticosteroid such as methylprednisolone may be considered. Methylprednisolone is associated with oral clefts in the fetus when used during the first trimester therefore, corticosteroids should be reserved as a last resort and should be avoided during the first 10 weeks of gestation.9,11... 

Monitor patients for adequate oral intake. If the patient has weight loss, assess whether enteral or parenteral nutrition is needed. 

It is common practice to discontinue oral feedings during an attack of acute pancreatitis. In theory, discontinuation of oral intake will decrease the secretory functions of the pancreas and minimize further complications from the disease. Some patients can be fed with minimal oral intake. Tube feeding delivered via a nasojejunal tube will feed the patient beyond the ampulla of Vater, minimizing stimulation of the pancreas.15,16 If oral intake is discontinued for a protracted period, total parenteral nutrition must be used to maintain adequate nutrition.17,18... 

Marik PE, Zaloga GP. Meta-analysis of parenteral nutrition versus enteral nutrition in patients with acute pancreatitis. BMJ 2004 328(7453) 1407. 

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