The Association of Pediatric Gastroenterology and Nutrition Nurses
Help & Hope for Children with Digestive Disorders GIKids
Journal of Pediatric Gastroenterology and Nutrition Journal of Pediatric Gastroenterology and Nutrition

Enteral and Parenteral Nutrition

Chapter quoted in part from:
Bentley D, Lifschitz C, Lawson M. Pediatric Gastroenterology and Clinical Nutrition. 2001.
ReMedica Publishing, London U.K. with permission.

Enteral and Parenteral Nutrition

The increased survival of severely ill patients has been made possible in part by the development of techniques that will secure their nutrition [1]. Whenever possible, the oral or enteral route is preferable; however, many patients are unable to receive appropriate calories in this manner and so require intravenous nutrition. This chapter describes these two techniques.

Enteral nutrition

Feeding by the enteral route is more physiologic than that by the parenteral route and consequently has fewer short-term and long-term complications. In addition, it is a less expensive option and easier to manage. The use of the gastrointestinal tract results in superior fluid homeostasis and - based on results from animal studies at least - function of the intestine is better preserved [2]. Feeding also initiates the activity of non-luminal neuronal and hormonal factors, which stimulate the bowel [3]. Consequently, only if the enteral route is precluded through an inability to ingest, digest, absorb, or propulse nutrients, should parenteral nutrition be indicated. Before nutritional supplementation of any kind is implemented, the nutritional status of the patient should be assessed, the goals defined, and the risks and benefits explained to the parents and, if age-appropriate, to the patient. Introducing and maintaining in position a nasogastrictube may be of little relevance to a physician, but constitutes a major trauma to certain patients as well as their families.

Oral supplementation

Oral supplementation is feasible whenever the patient is capable and willing to swallow a liquid formula and retain it in the stomach. In infants, increasing the caloric density of liquid formulas can be achieved by the addition of infant cereal, glucose polymers, and/or oil, depending on the age and tolerance of the patient. In some instances, powder preparations can be dissolved in a smaller volume than that recommended by the manufacturer, thus providing hypercaloric formulas. It needs to be remembered, however, that such modifications increase the osmolality of the preparation and so delay gastric emptying, which can cause vomiting, early satiety, diarrhea, and/or flatulence. At times, these complications will prevent the use of oral supplements even in patients willing to consume them.

Children with prolonged caloric deprivation and consequent growth failure may be unwilling to take significant additional calories over baseline requirements. In this situation, a concentrated preparation may be indicated before tube feeding is initiated.

Tube and gastrostomy feedings

There are many indications for tube feeding. The major ones include:

  • Inability to coordinate suck and swallow (prematurity, brain injury, increased intracranial pressure)
  • Debilitated newborn infants
  • Orofacial malformations
  • Severe respiratory illnesses
  • Cardiopathies [4]
  • Failure to thrive
  • Gastroesophageal reflux [5].

In addition, tube feeding may be indicated in altered sensorium, renal disease [6] , HIV infection [7], short-bowel syndrome [8], Crohn's disease [9], intestinal pseudo-obstruction [10], muscular dystrophy, anorexia nervosa, delayed gastric emptying, nutrient malabsorption, depression, and inappropriate caloric intake.

If oral supplements to food or a complete liquid diet can be taken, then these approaches are preferable to a tube method. Moreover, there are obvious psychological advantages in maintaining oral feeds. Children who will require total or supplemental feedings for a prolonged time and are dependent on a nasogastric tube for that purpose, are good candidates for the placement of a gastrostomy.

Tube feeding is contraindicated in the following conditions:

  • Extreme prematurity
  • Severe respiratory distress
  • Severe cardiac failure
  • Trauma, burns to the face
  • Malnutrition in a severely immunocompromised host
  • Severe vomiting, such as when chemotherapy is administered.

Gastrostomy

In children, gastrostomies can be placed surgically, laparoscopically [11], or percutaneously [12,13]. A percutaneous gastrostomy can be performed under ultrasonic or fluoroscopic control [14], or endoscopically (push or pull technique) [15]. If the patient does not suffer from severe gastroesophageal reflux, a gastrostomy can be carried out without the need for a fundoplication [16], even in neurologically impaired children [17]. However, following placement of a gastrostomy, patients can develop gastroesophageal reflux or delayed gastric emptying.

The technique of percutaneous endoscopic gastrostomy (PEG) was introduced in 1980 as a method requiring neither a laparotomy nor general anesthesia [18]. The technique originally described - the pull method - involves puncturing the apposed gastric and abdominal walls under endoscopic control. A suture is then passed from the exterior into the gastric lumen and grasped with a snare. The suture is pulled out of the mouth, affixed to the end of a gastrostomy tube, and then pulled back down into the stomach. The gastrostomy tube then exits the abdominal wall. Modifications of this technique have included pushing the gastrostomy tube over a guidewire (the push method) and direct puncture of the stomach under endoscopic control with an introducer and outer peel-away sheath. All of these options have been used with good results. The advantage of a percutaneous gastrostomy is that discharge from hospital occurs within 24 h. Although gastrostomies can be performed under conscious sedation and local anesthetic, when the procedure is undertaken in children, general anesthesia is often used.

The gastrostomy provides a transcutaneous and direct approach to the stomach. This method has several advantages:

  • It frees the orofacial area from tubes, tape, and manipulation
  • It avoids accumulation of nasal secretions and obstruction of the internal ear canal
  • It provides the patient with more privacy.

Complications can occur with gastrostomy tubes either at the time of placement or subsequently, and include [19]:

  • Skin infections
  • Leakage
  • Perforation of the colon
  • Separation between the gastric and abdominal wall, with intraperitoneal leak
  • Erosions to the gastric mucosa [20]
  • Aspiration pneumonia
  • Hemorrhage
  • Necrotizing fasciitis.

Children with neurological problems are at risk of aspiration, and tube feedings constitute an additional problem [21]. Contraindications for percutaneous gastrostomies comprise:

  • Massive ascites
  • Need for peritoneal dialysis
  • Portal hypertension
  • Severe coagulopathy
  • Abdominal wall infection.

Methods of tube feeding

Tube tips can be positioned in the stomach or duodenum, or surgically placed distal to an intestinal anastomotic site in the jejunum or ileum. The nutrients can be infused into the stomach by bolus (intermittent feeding regimen), which confers the benefit of simulating a normal pattern of feeding. Bolus feeding may be difficult in some very small preterm infants because of immaturity-associated delayed gastric emptying and poor antroduodenal motility [22]. Difficulties may also arise in those with gastroesophageal reflux or vomiting, as well as in patients receiving ventilatory support with high positive-end expiratory pressure (PEEP).
Alternatively, tube feeding can be used to provide a continuous infusion. Enteral feeding pumps are not as costly or as complex as those used for intravenous therapy. Constant infusions have the advantage of achieving a much higher fluid intake, less gastric distension and aspiration, as well as improved absorption of nutrients [23]. However, it may be better to have drugs infused as a bolus to prevent wastage and inaccuracies in dosages. Nocturnal infusions may interfere less with activity and daytime oral feedings.
Each anatomic position is associated with its own advantages and disadvantages. Tubes placed in the stomach are easy to replace, and feedings can be administered by bolus or gavage. In contrast, those sited in the small bowel can be dislodged and are difficult to reposition, and feedings need to be administered as a constant infusion via a pump. Potential hazards include perforation of the stomach or intestine, and aspiration, which can prove fatal, especially in very young or compromised patients.

Bowel endocrine response to feeding

When selecting the method of enteral nutrition it should be remembered that the gut hormone profile, both in preterm and in term infants, is influenced by the feeding regimen [24]. Postprandial responses are greater when there has been bolus feeding of milk as opposed to continuous intragastric infusions [25-27].
It has been suggested that milk in the gut results in the release of a number of hormones inducing developmental changes in the bowel and pancreas. Hormonal responses to the first extrauterine feed are dissimilar in the preterm and term infant, as the mature newborn is primed to respond to the initial feed with metabolic and endocrine changes. It would seem that developmental changes arise in the final weeks of gestation which prepare the term baby for enteral feeding.

Studies in very small preterm infants (birth weight <900 g) have shown numerous advantages to priming using a nasogastric tube with progressive increments of feeds over 20 days [28,29].

Equipment for tube feeding

Feeding tubes are manufactured from polyurethane, silicone rubber (Silastic), polyethylene, or polyvinyl chloride. Polyurethane and Silastic tubes are used more commonly than the other types as they are softer, cause less discomfort, and can remain in situ for several weeks. However, they have a small internal diameter and hence are not suitable for all types of feeds. In addition, pumps are often required. Usually, it is difficult to aspirate from this type of product, and the unweighted tube is easily dislodged by coughing.
Polyethylene and polyvinyl chloride tubes generally have a wider lumen and can be used for blenderized whole diets or home-prepared feeds. They are more suitable for bolus feeding than the polyurethane or Silastic products, although they, too, can be used for continuous infusion. Furthermore, they are easier to introduce than the softer tubes; however, they harden in situ and have been reported to cause gut perforation unless they are changed frequently (every 3-5 days).

For tubes positioned in the small bowel, radiologic confirmation is useful. For those located in the stomach, air can be injected and the end of the tube auscultated at the presumed site of the opening to ensure that the bronchi have not been cannulated.

Various containers and gavage sets are available when tube feeding is by continuous infusion. All containers must be sterile when the feed is introduced and should be changed every 12-24 h in order to reduce the likelihood of introducing pathogens. Pumps are available to deliver the infusate at a predetermined rate.

Products for tube feeding

Enteral feeds can be classified into three categories:

  • Chemically defined diets
  • Specifically formulated diets
  • Standard polymeric diets.

Chemically defined or elemental diets contain nutrients that require little or no digestion and hence are easily absorbed.  Specially formulated diets are those designed to overcome a specific problem in digestion such as lactose intolerance.

The standard polymeric diet has whole protein rather than amino acids as the nitrogen source and is appropriate where there is normal or near normal gastrointestinal function. Preparations suitable for tube feeding are of three types:

  • Normal food that has been blenderized and sieved
  • Reconstituted powder preparations which require the addition of water or milk>
  • Ready-to-feed products.

Blenderized food has the disadvantage that it is difficult to achieve a uniform consistency that will readily pass through an enteric feeding tube. Home-prepared feeds will block the small lumen of polyurethane or Silastic tubes. Feeds of this type are usually low in energy unless modular fat and carbohydrate are used. Furthermore, liquidized preparations might become contaminated - from the food directly, its processing, or from the use of unclean liquidizing equipment. For a child being fed at home via a gastrostomy, use of home-prepared foods may confer social and emotional benefits to the mother, child, and family; however, these preparations have a limited role in tube feeding.

Complete feeds, either ready-to-use or reconstituted powders, should contain the recommended dietary allowance (RDA) for all nutrients, including vitamins, minerals, and trace elements. If the patient does not tolerate the required calories through the enteral route, supplementary minerals and vitamins will need to be given intravenously. Ready-to-feed powders have advantages over reconstituted feeds in that they are sterile and less liable to preparation errors by hospital staff or parents. Unfortunately, they are both expensive and bulky for transport and storage. 

Modular products containing fat, protein, or carbohydrate can be used to formulate an entire tube feed, thus allowing greater flexibility of content [30]

Feeding different age groups

For those under 6 months of age, breast milk or a standard infant formula should be suitable. If nutrient requirements are high, it may be necessary to supplement with a milk fortifier in the case of breast milk, or with glucose polymers or fat in respect of an infant formula. In situations where an increased protein intake is indicated, formulas designed for preterm infants can be employed. After 6 months of age, infant formulas are generally used. However, beyond the age of 12 months, infant formulas fail to satisfy energy requirements if used as the sole source of nutrition. For infants aged between 12 months and 2 years, a specially designed complete formula is recommended. These formulas contain 1 kcal/ml (30 kcal/oz), equivalent to 1.48 kJ/ml (44.4 kJ/oz). The quantity of formula is determined by the fluid and energy requirements of the patient plus compensation for any energy deficit that may exist.

Energy supplements that provide over 1 cal/ml can cause diarrhea and, in general, should be used only in patients requiring both an increased energy intake and fluid restriction. Hypercaloric formulas, if introduced too rapidly or used in large quantities, may result in diarrhea or gastric retention. Initiation of tube feedings as a constant infusion may be responsible for a small but an increased number of liquid stools. However, this usually resolves within a few days.

Various products exist to meet the requirements of young children. Most powder and ready-to-feed preparations are designed to fulfill adult needs but can be used for children over the age of 2 years. Adult preparations usually supply more than the RDA for protein and sodium; however, provided levels of such are monitored, and vitamin and mineral deficits are supplemented, they offer an acceptable option.

Initiating tube feeding

Enteral feedings must be introduced gradually. Rapid increments can result in problems, particularly if the child has not been fed for more than 24 h or has evidence of gastroesophageal reflux or malabsorption. Generally, the first feeding can be with a formula (diluted to one-quarter to one-half strength) providing all the fluid needs unless the patient is also receiving intravenous fluids. When patients are also on intravenous regimens, increments in the rate of tube feeding should be accompanied by commensurate decreases in the parenteral fluids. Once the total fluid requirement of the half-strength dilution has been given, full-strength feeds can be gradually introduced over 1-2 days. Increasing both the volume and concentration of the feed on the same day often provokes abdominal pain and diarrhea.

Problems associated with tube feeding

Obstruction of the nasogastric tube may occur if it is inadequately rinsed after bolus feeding, especially if the tube is of the narrow-lumen polyurethane or Silastic type. A thick viscous tube feed containing discrete particles or a feed based on meat is the most likely to cause obstruction. Home-prepared feeds, whether derived from homogenized food or reconstituted powders, are more likely to cause obstruction than a commercially available ready-to-feed alternative. A solution with water and meat tenderizer or a cola drink injected through the tube may help resolve the obstruction.

The commonest problems are abdominal pain, flatulence, and diarrhea. Sometimes these features can be resolved by advancing the regimen more gradually. If gastrointestinal symptoms occur, return to half-strength feeds and/or decrease the fluid intake by roughly 15-20%. Gradually increase the volume over the next 3 days, then raise the concentration to three-quarters followed by full strength. If symptoms recur, consider administering the formula as a constant infusion; the rate then can be increased every other hour by 1-3 ml until the desired target - bases on the condition and weight of the patient - is reached.

For young children, the carbohydrate concentration should not be above 10 g/100 ml (10%) and the fat content should not exceed 5 g/100 ml (5%). When such is tolerated, further increments in volume can be made. If the patient is receiving intravenous fluids and has good venous access, it may be easier to provide a low volume of full-strength enteral nutrition and increase the quantity progressively. This avoids wastage of formula if the patient does not tolerate a higher concentration, because the rate can be easily decreased. In contrast, in patients with poor intravenous access, it may be better to secure volume intake through the enteral route, followed by a gradual increase in the concentration.

Delayed gastric emptying may be due to decreased gut motility, as is seen in premature infants, in cases of intestinal inflammation, and in the presence of primarily altered peristalsis. Alternatively, it may be the result of the bolus feeding of an over-concentrated hyperosmolar preparation. In such instances, a continuous infusion should be considered, and the volume and concentration of feeds decreased and subsequently gradually built up.

Overload of fluid and nutrients can occur if care is not taken in calculating the requirements of individual patients. RDAs for protein, fluid, and sodium should be particularly considered - excess protein, fluid retention, and edema secondary to a high sodium intake will cause a raised level of blood urea, especially if the patient has hypoalbuminemia. In those on fluid restriction, the volumes of intravenous fluids and medications need to be added to the tally of fluids administered.

Weaning from enteral nutrition

The transition process varies depending on the age of the patient and the initial indications for the enteral feedings [31]. In premature infants, as their suck and swallow improves [32], and gut motility matures [33], the infant will progressively take more by mouth. In older children, periods of fasting may be necessary to elicit hunger and increase the amount of oral feedings. Tube supplements following the oral intake or nighttime supplementation may aid in the weaning process.

Monitoring

Growth, fluid intake, adjustments for differences in the seasonal ambient temperature, and other nutritional parameters need to be supervised, particularly during the early phases.
Children on tube feeding require a team approach to ensure appropriate nutrition (nutritionist), continuation of development of oromotor skills and intake of nutrients by mouth whenever possible (speech therapist), appropriate support of the equipment and ostomy site (ileostomy/colostomy nurse practitioner), and psychological support whenever necessary [34].

Total parenteral nutrition

Total parenteral nutrition (TPN) has been one of the most innovative techniques to be introduced into pediatrics in the last 50 years. However, because of the development of enteral nutrition - using elemental diets and constant infusion techniques - TPN is nowadays indicated less often than it has been. Although enteral nutrition is the preferred route of feeding, TPN administered through a peripheral or central vein should be instituted without major delay whenever needs cannot be met by the enteral route. Advantages and disadvantages of intravenous nutrition are listed in Table 2.1.

Peripheral TPN is sufficient in certain cases, while in others, central vein access, which allows for greater volumes and high glucose concentrations, is indicated (Table 2.2).

Total intravenous nutrition necessitates considerable clinical and pharmaceutical expertise and laboratory support to minimize biochemical, bacteriological, and surgical complications. Infusates must be prepared aseptically. Experienced nursing care must be available to resolve problems related to the catheter, and the patient must be monitored closely.

Metabolic disturbances and/or dehydration must be corrected before TPN is commenced.

Composition of infusions

The infusate should contain the following:

  • Protein - crystalline amino acids
  • Fat - lipids
  • Carbohydrate - glucose
  • Electrolytes - sodium, potassium, chloride, calcium, phosphate, and magnesium
  • Metals/trace elements - zinc, copper, manganese, chromium, and selenium (the role of iron in parenteral nutrition regimens is controversial)
  • Vitamins - A, C, D, E, K, B1 (thiamine), B2 (riboflavin), niacin, pantothenic acid, B6 (pyridoxine), B12, biotin, choline (cofactor for enzymatic reactions), and folic acid.

Acetate is used to correct metabolic acidemia.

Amino acids

Protein requirements can be met by providing the appropriate amounts of amino acids. The range in adults is from 0.5 to 3.5 g/kg/day. Blood urea, nitrogen, and albumin should be monitored. To obtain information on recent protein synthesis, a serum prealbumin, fibronectin, or retinol-binding protein can be measured.
L-amino acids are preferred to D-amino acids because they are more effective in maintaining nitrogen balance and protein synthesis. There are a number of commercial preparations available. The latest amino acid solutions to be introduced, such as TrophAmine and Aminosyn PF, are formulated to meet the needs of premature infants. At times of specific nutritional needs, the non-essential amino acids may become essential or semi-essential. Furthermore, quite apart from the eight amino acids known to be essential for adults, histidine, proline, and alanine are required by the young infant. Cystine and/or cysteine are also necessary for growth and so become semi-essential or essential, as opposed to non-essential, amino acids.

Nitrogen balance studies allow the clinician to ensure that the protein intake is at a safe level. The balance is the difference between nitrogen intake and nitrogen losses in the urine (as urinary urea), stools, and sweat. Losses can also occur through the skin in burn patients. Starvation and infections result in a state of negative balance, and rapid growth a positive balance.

Lipids

Parenteral lipids provide high energy in a relatively small volume with a low osmolar load and are also a source of the essential fatty acids, linoleic and linolenic acids. Fat emulsion solutions are available as 10% or 20% preparations, with osmolalities of 280 mosmol/kg and 330 mosmol/kg, respectively. They are derived from soybean, safflower, or cotton-seed oil, with the fat mainly present as triglyceride. The ultimate total daily dose of parenteral lipid emulsion should not exceed 4 g/kg [35] and the infusion rate should be less than 0.25 g/kg/h. During the first week of life for low-birth-weight infants, the amount of lipids should not exceed 0.5-1 g/kg/day. The 20% emulsion provides approximately 2 kcal/ml (8.4 MJ/l) and is cleared more rapidly than the 10% solution.

Lipid emulsions are contraindicated in the following chemical/biochemical circumstances:

  • Serum bilirubin >100 µmol/l (6 mg/dl)
  • Serum pH <7.25
  • Serum triglycerides >7.8 mmol/l (300 mg/dl).

Free fatty acids may displace bilirubin from albumin in the neonate, with the risk of kernicterus [36]. Lipids may also interfere with platelet function and should be withheld if the count is less than 50,000 ´ 10 9/l in the face of hypertriglyceridemia.

Infused lipid is hydrolyzed by lipoprotein lipase, an enzyme present in the endothelial cells of blood vessels. Lipids that are not cleared from the circulatory system are at greater risk of being deposited in the lung and brain, especially in the growth-retarded (IUGR) baby. Both the IUGR and the premature baby, as well as septic or severely stressed patients, are impeded in their ability to clear intravenous lipid particles.

Carbohydrate

Glucose is the sole monosaccharide used for intravenous nutrition. A solution with a glucose concentration of more than 10-12.5% is too hyperosmolar for peripheral use, while a concentration of up to 40% can be administered via a central line. The recommended amount of glucose to be infused is 10-20 g/kg/day. Urine must be closely monitored for glucose spillage. Patients who experience glucosuria, such as those who are infected, stressed, or with cystic fibrosis, may benefit from the addition of insulin to the intravenous mixture (one unit of regular insulin per 10 g of glucose). Glycerol present in Intralipid is another source of carbohydrate. Other sugars such as fructose, galactose, and sorbitol have been suggested, but fructose (via lactate and pyruvate) can cause a metabolic acidosis and hypoglycemia. In addition, sorbitol is metabolized to fructose.

Vitamins

A multivitamin preparation, such as Multibionta Infusion (Merck) or MVI Pediatric (Amour), should be given daily. Multibionta given in dextrose saline at a rate of 0.15 ml/kg/day supplies all vitamin requirements. For MVI, the dose depends on the weight/age of the patient:

  • £2.5 kg - 40% (2 ml) of an MVI Pediatric vial per kg per day
  • >2.5 kg to 11 years - 1 vial (5 ml) of MVI Pediatric per day
  • >11 years - 1 vial (10 ml) of MVI-12 + 20 µg of vitamin K per day.

Minerals and Trace Minerals

Iron is not part of the mineral preparation. Whenever needed, iron can be administered as Imferon (Fisons Ltd) in intramuscular (very painful) injections. To avoid leakage along the needle track with subsequent skin staining, a suitable injecting technique must be used. Because of the risk of allergic reactions, tolerance needs to be tested initially by giving small doses of iron under supervision.
Daily intravenous needs of some essential trace elements are listed in Table 2.3.
Aluminium toxicity is no longer a problem with current TPN solutions in term infants and older children, but may still be of concern in preterm infants [37]

Technique of TPN

Because there is a considerable risk of septicemia when using intravenous catheters, especially one which is centrally located, a peripheral or scalp vein should be used whenever possible. A 0.22-µm filter is recommended when using intravenous fluids.

Frequent repositioning of the infusion site (every 2 or 3 days) is advisable to avoid phlebitis. Ultimately, a catheter may need to be sited in a central vein under aseptic conditions.
Options include percutaneously inserted fine Silastic central venous catheters (0.64 mm inner diameter or 0.94 mm outer diameter) - longlines - and surgically placed Broviac catheters. Silicone catheters are inert, soft, and radiopaque, and are thus less likely to cause thrombosis or perforation. Furthermore, they inhibit fibrin formation. The site of the longline must be checked radiologically because, if the tip is within the heart, infusions could produce arrhythmias.

The use of peripherally inserted central venous catheters (PICCs) to provide prolonged intravenous access in children is increasing. PICCs have been shown to provide reliable and safe access for prolonged intravenous therapy in both neonates and children. In one study, 441 PICCs were inserted into 390 patients aged between 0 and 22 years [38]. No insertion complications occurred. Treatment of infectious disease was the most frequent reason (46%) for PICC insertion. The average catheter life was 13 ± 12 days. Similar complication rates with use in and out of hospital suggest that home intravenous therapy can be safely delivered with PICCs, thereby avoiding expensive hospitalization.
           
Day 1: Provide necessary volume to cover fluid requirements. Use:

  • Peripheral-strength (10-12%) glucose solution
  • 20% Intralipid (or 10%) 0.5 g/kg
  • Trophamine (or equivalent amino acid preparation).

Days 2-4: Increase progressively to provide total energy requirements, therefore:

  • Double volume of Intralipid
  • Double concentration of glucose
  • Adjust concentration of amino acids.

Some basic daily clinical measurements are essential whenever TPN is initiated. The patient must be weighed, the total urine volume recorded, and the quantity of any lost body fluids (e.g. via nasogastric or gastrostomy tubes) noted. A state of positive nitrogen balance should be attained because stools will be infrequent during TPN, therefore there is little loss of fecal nitrogen.

Lipids must be monitored by measuring serum triglycerides 4 h after initiation of the infusion, also whenever the rate is increased or if the patient's clinical status deteriorates. Once a given rate of lipid infusion is well tolerated, serum triglycerides should be remonitored less frequently (once a week to once a month).

Precautions and complications

Sepsis is the most frequent serious complication during TPN, resulting in increased morbidity, mortality, and healthcare costs [39]. A meticulous aseptic technique is essential when handling the infusion apparatus, particularly upon injecting into the system. Septicemia is more probable when central catheters are used. Common sources of infection include Staphylococcus aureus, Staphylococcus epidermidis, Candida species, Pseudomonas species, and Escherichia coli.

Sudden termination of TPN can cause hypoglycemia, particularly in malnourished patients. In patients on cyclic TPN, the rate should be halved for 1 h prior to discontinuing it.

Cholestasis and, rarely, cirrhosis leading to liver failure are known hazards of TPN in neonates and children with short-bowel syndrome [40]. There are data to suggest that intravenous amino acid mixtures play a role in the development of cholestasis in the very-low-birth-weight infant [41]. Oral administration of ursodeoxycholic acid (15-45 mg/kg/day divided into two or three doses) may improve cholestasis. Pancreatitis is a rare but possible complication [42]. There is a clear association between complete withdrawal of enteric feeding and intestinal mucosal atrophy as well as pancreatic hyposecretion. Non-enteral feeding causes a reduction in brush-border enzyme activity, therefore an early return to normal feeding is important. Small volumes of oral nutrients should be used whenever possible.

For details of monitoring during TPN, see Table 2.4.

Transitioning to enteral nutrition

Oral feeds should be reintroduced very slowly with full TPN back-up. Feeds should be diluted and given in small frequent doses.

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30. Davis A, Baker S. The use of modular nutrients in pediatrics. J Parenter Enteral Nutr 1996;20:305.

31. Schauster H, Dwyer J. Transition from tube feedings to feedings by mouth in children: preventing eating dysfunction. J Am Diet Assoc 1996;96:277-81.

32. Lemons PK, Lemons JA. Transition to breast/bottle feedings: the premature infant. J Am Coll Nutr 1996;15:126-35.

33. Tawil Y, Berseth CL. Gestational and postnatal maturation of duodenal motor responses to intragastric feeding. J Pediatr 1996;129:374-81.

34. Mascarenhas MR, Redd D, Bilodeau J, Peck S, Liacouras CA. Pediatric enteral access center: a multidisciplinary approach. Nutr Clin Pract 1996;11:193-8.

35. American Academy of Pediatrics Committee on Nutrition. Pediatric Nutrition Handbook, 4th ed. American Academy of Pediatrics,1998.

36. Morris S, Simmer K, Gibson R. Characterization of fatty acid clearance in premature neonates during intralipid infusion. Pediatr Res 1998;43:245-9.

37. Bishop NJ, Morley R, Day JP, Lucas A. Aluminum neurotoxicity in preterm infants receiving intravenous-feeding solutions. N Engl J Med 1997;336:1557-61.

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39. Yeung CY, Lee HC, Huang FY, Wang CS. Sepsis during total parenteral nutrition: exploration of risk factors and determination of the effectiveness of peripherally inserted central venous catheters. Pediatr Infect Dis J 1998;17:135-42.

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42. Dabbas M, Colomb V, de Potter S, et al. Pancreatitis in children on long-term parenteral nutrition. Transplant Proc 1996;28:2782.

Table 2.1 

Advantages and disadvantages of intravenous nutrition.

Advantages

Disadvantages

Guaranteed caloric intake Complete absorption Relatively comfortable Does not worsen gastrointestinal problems High percentage of tolerance Socially acceptable (no visible tubing)

Risk of infection High cost Management requirements Need for sophisticated infrastructure (nursing, medical, technical, and laboratory)

         

Table 2.2  

Indications and requirements for total parenteral nutrition (TPN).

Peripheral TPN

Central TPN

Nutritional status not severely compromised

Poor nutritional status

Patient able to tolerate some nutrition orally or enterally

Patient unable to tolerate any nutrition enterally

Recovery time predicted to be short

Expected prolonged need of nutritional support

Good venous access

Poor peripheral venous access

                                                                                                        

Table 2.3  

Daily intravenous needs of some essential trace elements.

Trace element

Infants weighing <2.5 kg

Older children

Zinc

100-400 µg/kg

4,000 µg

Copper

10-40 µg/kg

1,600 µg

Chromium

0.1-0.4 µg/kg

16 µg

Manganese

2.5-10.0 µg/kg

400 µg

Selenium

1.5-2.0 µg/kg

8 µg

                           

Table 2.4 

Monitoring of total parenteral nutrition (TPN).

 

Neonate

Child/Adolescent

 

Initial*

Subsequently

Initial*

Subsequently

Strict I/O

Daily

Daily

Daily

Daily

Urinary glucose

Every void

Every shift

Every void

Every shift

Electrolytes, BUN

2-3 times per week

Every week

2-3 times per week

Every week

Ca, P, Mg

Every week

Every other week

2 times per week

Every week

Alkaline phosphatase, albumin

None

Every other week

Every week

Every other week

Triglycerides

4 h post initial infusion

With each change

4 h post initial infusion

With each change

Prealbumin

See below

 

See below

 

*First 3-7 days, depending on the patient's stabilityI/O = input and output; BUN = blood urea nitrogen

Prealbumin: Test 24-48 h post TPN initiation to assess adequacy of protein intake. Monitor with any change in status or protein intake, or to assess adequacy of intake. May be falsely elevated with renal disease.

Triglycerides:  If greater than 150 mg/dl (2 mmol/l), halve rate of infusion and retest to assess tolerance. Lipoprotein lipase is an inducible enzyme and tolerance to lipids will generally improve with time. Check baseline triglycerides in septic patients and in those with pancreatitis, renal disease, or diabetes. If markedly elevated, contact the Nutrition Support Team.

Ionized calcium: Check when serum calcium levels are altered by low albumin.

Zinc: Zinc status should be assessed in patients with increased gastrointestinal losses, inflammatory bowel disease, cystic fibrosis, or fistulas.

Transaminases/bilirubin: Check monthly with patients on long-term TPN (greater than 2 weeks) or TPN-dependent patients.