Providing Nutrition Clinically

An overview of the different routes for administration of nutritional support, including total parenteral nutrition and supplemental parenteral nutrition, and their benefits and considerations.

There are three routes for administration of nutritional support:

  • Oral nutritional support - the modification of foods and fluids by fortifying food with protein, carbohydrate and/or fat plus minerals and vitamins (e.g. the provision of snacks and/or oral supplements)
  • Enteral tube feeding - the provision of calories, protein, electrolytes, vitamins, minerals, trace elements, and fluids via an intestinal route
  • Parenteral nutrition (PN) - the provision of calories, amino acids, electrolytes, vitamins, minerals, trace elements, and fluids via an intravenous route.

To determine whether oral, enteral, or parenteral nutrition should be utilized, healthcare professionals should first assess gastrointestinal (GI) function to see if a patient can be fed orally or enterally. The provider will also need to evaluate the state of malnutrition and the level of physiological stress before setting the nutritional goals.

Enteral Nutrition
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Enteral nutrition (EN) is indicated for patients with a functional GI tract whose oral nutrient intake is insufficient to meet estimated needs.1 The most commonly used method of enteral access is the nasoenteric tube, because it can be inserted into the stomach, duodenum, or the jejunum.1 These tubes are indicated for short-term use (<4 weeks), have low complication rates, and are relatively inexpensive.1 Patients requiring long-term EN (>4 weeks), or in whom nasal intubation is impossible should receive a gastrostomy as a method for long-term access, because it eliminates nasal irritation, psychosocial stress of having a tube in the nose, and requirement for an infusion pump (Figure 1).1

Figure 1. Routes of administration in EN

Parenteral Nutrition
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PN administration of nutrients in high concentrations by PN requires central venous access.1 Subcutaneously tunneled percutaneous catheters or implanted subcutaneous infusion ports are mostly used for long-term therapy in a non-hospital setting.1,2 Temporary percutaneously inserted central catheters (PICCs) advanced into the superior vena cava (SVC) are the route of choice for the delivery of PN in hospitalized patients.1 Catheter tip placement must be achieved and verified prior to use. Access to the SVC can be gained through the internal jugular vein or the subclavian vein with a central vein catheter (CVC) (Figure 2).1

Figure 2. Routes of administration in PN

Enteral nutrition in the pediatric setting
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Conditions for which EN may be considered include: immaturity (disorders of sucking and swallowing), infants too sick to nipple-feed, mechanically-ventilated infants, infants whose nutrient and/or calorie needs cannot be met by oral feeding, and infants with conditions such as chronic lung disease, cystic fibrosis, congenital heart disease, alimentary tract disease or dysfunction, renal disease, hypermetabolic states, severe trauma, and neurological disease.3

EN may be delivered pre-pyloric, directly into the stomach, or post-pyloric, distal to the stomach.4 Generally in children, a gastrostomy tube is the most common method used for long-term enteral access. The Committee on Nutrition of the European Society for Paediatric Gastroenterology, Hepatology, and Nutrition (ESPGHAN) recommend that post-pyloric feeding should be avoided in preterm infants, and reported that transpyloric feeding has been associated with increased gastrointestinal disturbance (relative risk [RR] 1.45, 95% confidence interval [CI] 1.05–2.09), and increased mortality (RR 2.46, 95% CI 1.36–4.46) compared to gastric feeding.4 The American Society for Parenteral and Enteral Nutrition (ASPEN) guidelines state that there are insufficient data to recommend the appropriate site (gastric versus post-pyloric/transpyloric) for enteral feeding in critically ill children. Post-pyloric or transpyloric feeds may improve caloric intake when compared to gastric feeds. Post-pyloric feeding may be considered in children at high risk of aspiration, or those who have failed a trial of gastric feeding.5 The ASPEN guidelines state: 'For premature infants weighing <1500 g and at risk for necrotizing enterocolitis (NEC), it is recommended that mothers be encouraged to supply breast milk for their infants.6

EN complications may include: tube malposition, resulting in delivery of nutrients upstream or downstream from intended site of infusion (leading to aspiration or dumping); nasal congestion or erosion with nasogastric tubes; migration of gastrostomy feeding tube; tube occlusion; gastrointestinal complications, such as diarrhea; and oral aversion (long-term tube feeding without nipple feeding). Although less frequent with EN than with PN, metabolic complications can also arise, including refeeding syndrome (resulting in hyperglycemia, hypokalemia, hypophosphatemia, and hypomagnesemia), nutrient deficiencies, and metabolic bone disease.3

Parenteral nutrition in the pediatric setting
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PN is indicated in infants and children who are unable to tolerate adequate enteral feedings to sustain nutritional requirements. This can include: premature infants; infants/children in whom prolonged starvation is anticipated (necrotizing enterocolitis, pancreatitis, graft-versus-host disease or postoperatively); and pediatric patients with inadequate intestinal nutrient absorption (e.g. short-bowel syndrome, intestinal pseudoobstruction, postchemotherapy).3

Umbilical vessels may be directly accessed during the first few days of life in neonates and this route of central venous approach can be used for PN. Due to risk of thrombotic complications, their use as a bridge procedure while awaiting placement of a long-term device is limited.7

Preterm infants often have a physiologically immature GI tract. As a result, EN alone may be insufficient to meet their nutritional needs. These infants may require PN to prevent nutritional deficits and death.7 Since preterm infants have low nutritional reserves and high metabolic needs, it is important that PN is initiated soon after birth (amino acids supplied on the first postnatal day) when it is clear that enteral feeds will not be tolerated or sufficient.7 Indications for PN in neonates are listed in Table 1.

Table 1. Important indications for parenteral nutrition in neonates8

Indication for PN
Diaphragmatic hernia
Hirschsprung disease8
Intestinal atresias8
Meconium ileus8
Meconium peritonitis8
Necrotizing enterocolitis3
Short bowel syndrome

An overview of the PN associated complications detailed in the ESPGHAN guidelines are summarized in Table 2.

Table 2. Parenteral nutrition associated complications.7

Parenteral nutrition associated complications Examples of complications
Central venous catheter- (CVC-) related e.g. Infection, occlusion, central venous thrombosis/pulmonary embolism, phlebitis, accidental removal
Compatibility issues e.g. Drug/medication incompatibility (precipitation)
Metabolic or nutritional e.g. Hypo/hyperglycemia, electrolyte disturbances, hyperlipidemia, acid-base disturbances, refeeding syndrome, hypertriglyceridemia, metabolic bone disease, hepatobiliary complications (e.g. cholestasis, PN--associated liver disease [PNALD]), growth retardation
Stability issues e.g. Storage time, light and oxygen exposure, admixture composition, significant temperature variability
Solution contamination e.g. Contamination by particles, microbes or extraneous material during aseptic technique

Adapted from J Pediatr Gastroenterol Nutr, 41(Suppl. 2), Koletzko B, Goulet O, Hunt J, et al. Guidelines on Paediatric Parenteral Nutrition of the European Society of Paediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) and the European Society for Clinical Nutrition and Metabolism (ESPEN), Supported by the European Society of Paediatric Research (ESPR), pp. S1–S87., Copyright (2005), with permission from ESPGHAN.

Enteral and parenteral nutrition in the adult patient
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Standards of practice (defined as a benchmark representing a range of performance of competent care that should be provided to ensure safe and efficacious nutrition care) from ASPEN for nutritional support in adult hospitalized patients suggest that the route selected for provision of nutritional support therapy should periodically be re-assessed to ensure that it is still adequately meeting the goals of the nutrition care plan (Figure 3).9

Figure 3. Route of administration algorithm9

Ukleja A, Freeman KL, Gilbert K, et al. Nutr Clin Pract (25, 4) pp. 403–414, copyright © 2010 by American Society for Parenteral and Enteral Nutrition. Reproduced by permission of SAGE Publications.

Oral nutrition support should be considered for those at risk of malnutrition who can swallow safely before considering enteral tube feeding or PN.10

Tube feeding should be considered for patients who cannot or will not eat, for patients who have a functional gut, and for whom a safe method of access is possible.11 In elderly patients, EN should be started early, as soon as nutritional risk becomes apparent.12

The timing of PN in ICU patients differs between ASPEN and ESPEN guidelines. ESPEN guidelines state that 'ICU patients who are not expected to be on normal nutrition within 3 days should receive PN within 24–48 h if EN is contraindicated, or if they cannot tolerate EN'.13 ESPEN guidelines also state Supplementary Parenteral Nutrition should be started in all ICU patients receiving less than their targeted enteral feeding after 2 days should be considered.13

ASPEN guidelines state that in the patient who was previously healthy before critical illness, with no evidence of protein-calorie malnutrition, use of PN should be reserved and initiated only after the first 7 days of hospitalization (when EN is not available).14 PN without soy-based lipids may commence in the first week of ICU hospitalization when PN is required and EN is not feasible.14

The most recent and largest meta-analysis of 27 randomized, controlled studies in 1,829 adult patients suggested that enteral feeding was associated with a lower infective risk than PN (RR 0.66; 95% CI 0.56–0.79).15 The risk of nutritional support complications was higher with enteral feeding than PN (RR 1.36; 95% CI 0.96–1.83; P=0.03). Overall, the risk of mortality was similar for enteral feeding compared with PN (RR 0.96; 95% CI 0.55–1.65).15

EN and PN modes of administration and considerations for use in adults are summarized in Table 3.

Table 3: Enteral and parenteral nutrition in the adult setting

Type of clinical nutrition Mode of administration
Enteral Nutrition Nasogastric tube, nasoenteral, PEG1 PEJ, PEG-PEJ16
Total Parenteral Nutrition Percutaneously inserted catheters advanced into the superior vena cava1Accesses:
Through peripheral veins in the arms (peripherally inserted central catheters)1
Through the internal jugular or the subclavian vein (central venous catheters)1

PEG, Percutaneous endoscopic gastrostomy; PEJ, percutaneous endoscopic jejunostomy; JET-PEG, jejunal tube PEG; NCJ, needle catheter jejunostomy

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  10. National Institute for Health and Clinical Excellence (NICE). Clinical guideline 32;London: NICE, 2006.
  11. American Gastroenterological Association. American Gastroenterological Association Medical Position Statement: Guidelines for the use of enteral nutrition. Gastroenterology 1995;108:1280–1301.
  12. Volkert D, Berner YN, Berry E, et al. ESPEN Guidelines on Enteral Nutrition: Geriatrics. Clin Nutr 2006;25:330–360.
  13. Singer P, Berger MM, Van den Berghe G, et al. ESPEN Guidelines on Parenteral Nutrition: intensive care. Clin Nutr 2009;28:387–400.
  14. Martindale RG, McClave SA, Vanek VW, et al. Guidelines for the provision and assessment of nutrition support therapy in the adult critically ill patient: Society of Critical Care Medicine and American Society for Parenteral and Enteral Nutrition: Executive Summary. Crit Care Med 2009;37:1757–1761.
  15. Braunschweig CL, Levy P, Sheean PM, Wang X. Enteral compared with parenteral nutrition: a meta-analysis. Am J Clin Nutr 2001;74:534–542.
  16. Fang JC, Bankhead R, Kinikini M. Enteral access devices. In: Mueller C, ed. The A.S.P.E.N. Adult Nutrition Support Core Curriculum, 1st ed., 2012, American Society of Health-System Pharmacists.