Enteral Feeding

Compared with enteral feeding, parenteral nutrition was associated with selectively enhanced activation of the coagulation system (plasma concentrations of thrombin-antithrombin III complexes) during endotoxemia.

From: Meyler's Side Effects of Drugs (Sixteenth Edition) , 2016

Enteral Feeding

D.L. Waitzberg , R.S. Torrinhas , in Encyclopedia of Food and Health, 2016

Formulation

The EN can be administered intermittently or continuously. Selection of pathway for EN administration and the type of infusion to be adopted will influence its formulation design. This also involves determining the total period for diet administration, the volume to be infused, infusion rate, if gravity drip will be used, and in which form it will be provided (infusion pump or by bolus). Table 2 outlines the programming of EN according to feeding tube positioning in pre- or postpyloric location.

Table 2. Programming of EN according to feeding tube positioning

Tube feeding position Volume Osmolality Fractionation Administration time
Stomach Allows high-volume supply Hyperosmolar solutions are tolerated, but the higher solution osmolality the slower stomach emptying Depends on the total volume/day and patient tolerance. Lower fractionation (four to six times per day) and higher volume in each supply may be used About 120 drops per min (or time (min)   =   total volume (ml)/6) from the beginning of therapy
Postpyloric During intermittent supply, the volume should not exceed 300   ml   h−   1 in adapted patients Better tolerance for formulations with less than 550   mOsm   l−   1; dripping of hyperosmolar solutions should be strictly controlled by using infusion pump Continuous or intermittent fractionation, generally between six and eight supplies per day in each 3   h Initial phase: 60 drops/min (or time (min)   =   total volume (ml)/3); 'adapted' phase: 120 drops per min (or time (min)   =   total volume (ml)/6)

Enteral formulations should be nutritionally complete when used as exclusive nutrition or as a supplement to patients with normal oral ingestion; or nutritionally incomplete when used only as a supplement nutrition. The evaluation of the digestive and absorptive capacity of the patient should be performed for better enteral formula selection ( Scheme 2 ).

Scheme 2. Planning for selection of enteral diets.

Several enteral formulations are based on fresh food, processed food, or both fresh and processed food. Therefore, nutrients comprising EN are generally the same constituents of a normal diet, consumed by the oral route, including carbohydrate (40–60% total energy needs), protein (14–20% total energy needs), fat (15–30% energy needs), and fiber (40–20   g   l−   1). Different factors should be considered to facilitate the choice of the most appropriate enteral formulation for patients with EN indication, such as caloric density, osmolarity and osmolality, administration pathway, source and complexity of nutrients, and disease.

The EN caloric density (kcal   ml−   1) should be based on the patient's total calorie needs versus the volume of enteral diets to be administered per day. Enteral diets with higher energy density have a lower amount of water, which can range from 690 to 860   ml   l−   1 diet. The categorization of enteral formulas, according to its energy density, is shown in Table 3 .

Table 3. Categorization of enteral formulas according to its energy density

Energy density Value (kcal   ml−   1) Formula
Very low <   0.6 Sharply hypocaloric
Low 0.6–0.8 Hypocaloric
Standard 0.9–1.2 Normocaloric
High 1.3–1.5 Hypercaloric
Very high >   1.5 Sharply hypercaloric

Vitamin and mineral supply varies according to the specific needs of the patients and their disease. In the specific nutritional needs, you should evaluate the indication of additional micronutrient supplementation, even when the formulation, per se, achieves those values recommended by the Recommended Dietary Allowance (RDA). Clinical nutritional patient evaluation should include objective and/or subjective indicators to identify, as early as possible, any risk of specific micronutrient deficiency for it to be immediately corrected and/or prevented.

Some specialized and very specific formulations to particular clinical situation (e.g., renal failure) are insufficient in some vitamin and mineral supply. Therefore, EN dietary planning attends to the need for supplementation or not of these micronutrients. For the long-term use of incomplete enteral feeding, the supplemental vitamins and minerals should be indicated.

In patients with malabsorption syndromes, investigate the possible fat soluble vitamins (A, D, E, and K) deficiency to correct it shortly. There is a lack of specific vitamin and mineral recommendations for critically ill patients. However, in such a condition, the needs of antioxidant nutrients are increased due the oxidative stress, and it is recommended to supplement vitamins A, C, and E, zinc, and selenium.

EN osmolality (mmol   l−   1 solution) and osmolality (mOsm   kg−   1 water) are associated with its digestive tolerance. Although the stomach tolerates diets with higher osmolality, more distal portions of the gastrointestinal tract respond better to isosmolares formulations. Therefore, hyperosmolar diets infused by gastrostomy or nasogastric feeding tube have better digestive tolerance when compared with administration by postpyloric or jejunal probes.

The nutrients that most affect the osmolality of a solution are simple carbohydrates (mono- and disaccharides), which have greater osmotic effect than the higher molecular weight carbohydrates (starch); minerals and electrolytes, due the property of its dissociation into smaller particles (e.g., sodium, potassium, and chloride); hydrolyzed proteins; crystalline amino acids; as well as medium-chain triglycerides, because they are more soluble than long-chain triglycerides. The more hydrolysates components contains the formulation, the higher its osmolality.

Enteral diets should not exceed the value of the renal solute load tolerated by the kidneys (800–1200   mOsm, in normal situation). Renal solute load can be calculated by adding 1   mOsm for each mEq of sodium/potassium/chloride, and 5.7   mOsm (adults) or 4   mOsm (children) for each gram of protein from its formula. Special attention should be given to critical clinical situations, such as sepsis, postoperative, polytrauma, and severe burn, where the urine becomes very dense, with high osmolality (around 500–1000   mOsm   kg−   1), even under appropriate hydration.

Importantly, the influence of the medication osmolality is usually neglected. The mean osmolality of liquid medications administered orally or by feeding tube ranges from 450 to 10   950   mOsm   kg−   1 water. Certain manifestations of gastrointestinal intolerance may be related to the medication, although it is often attributed to enteral formulation.

In specific clinical situations, there may be demands for change in the types of nutrients used; the quantity and/or form these should be presented. In such cases, nutritional therapy becomes more specialized. These adaptations involve changes from simple source of nutrients used until its physicochemical and structural modifications. Thus, specialized formulations for enteral use may provide different sources of vitamins, minerals, carbohydrates, lipids, and proteins, and these nutrients may be presented in their entirety or hydrolyzed (wholly or partly) structure.

Some specialized EN formulations are part of immunonutrition. The immunonutrition is a nutritional intervention that explores the particular activity of various nutrients in alleviating inflammation and modulating the immune system, in which are included the omega-3 fatty acids, arginine, glutamine, nucleotides, and antioxidants. There is a current consensus that perioperative immunonutrition can beneficiate elective surgical patients, especially those malnourished patients submitted to major gastrointestinal surgery. In these patients, administration of enteral diets containing n-3 PUFA, nucleotides and arginine contributes to decrease postoperative infectious and noninfectious complications and must be initiated 5–7 days preop (500–1000   ml day−   1) and maintained in the postoperative period.

Although the benefit of using this enteral formula combining different nutrients with immunomodulatory functions is well established in surgical patients, data are lacking to confirm or guide the effective and safe use of enteral diets containing isolated immunonutrients in different clinical populations, including arginine and glutamine. In hemodynamically stable condition, arginine may offer immunologic and metabolic benefits, but its participation in the synthesis of nitric oxide may constitute a potential risk for septic patients. Enteral glutamine should be considered to treat burn patients and trauma victims, but there is not sufficient evidence for its use in critically ill patients with failure of multiple systems.

Other nutrients that may compose specialized EN formulations include the branched chain amino acids (BCAAs). BCAAs provide primary fuel for skeletal muscle during stress and sepsis. Therefore, leucine, isoleucine, and valine may be added to specialized EN formulas as supplemental metabolic sources to attend the metabolic needs of skeletal muscle during hypermetabolic conditions.

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Nutrition and Cystic Fibrosis

Zhumin Zhang , ... HuiChuan J. Lai , in Nutrition in the Prevention and Treatment of Disease (Fourth Edition), 2017

b Enteral Feedings

Enteral feeding can be initiated when oral supplementation does not improve growth and nutritional status significantly. The goals of enteral feeding should be explained to the patient and family, that is, as a supportive therapy to improve quality of life and outcome, and their acceptance and commitment to this intervention should be realistically assessed.

Enteral feeding can be delivered via nasogastric tubes, gastrostomy tubes, and jejunostomy tubes. The choice of enterostomy tube and technique for its placement should be based on the expertise of the CF center. Nasogastric tubes are appropriate for short-term nutritional support in highly motivated patients. Gastrostomy tubes are more appropriate for patients who need long-term enteral nutrition. Jejunostomy tubes may be indicated in patients with severe GERD; use of predigested or elemental formula may be needed with jejunostomy feeding.

Standard enteral feeding formulas (complete protein, long-chain fat) are typically well tolerated. Calorically dense formulas (1.5–2.0   kcal/mL) are usually required to provide adequate energy. Nocturnal infusion is encouraged to promote normal eating patterns during the day. Initially, 30–50% of EER may be provided overnight. Pancreatic enzymes should be given with enteral feeding. However, optimal dosing regimen is unclear with overnight feeding.

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NUTRITIONAL SUPPORT | Adults, Enteral

K.N. Jeejeebhoy , in Encyclopedia of Human Nutrition (Second Edition), 2005

Optimizing Enteral Nutrition and Reducing Risk of Aspiration Pneumonia

Enteral feeding is associated with several factors that may result in reflux of gastric contents and aspiration: the supine position of the patient, the presence of a nasogastric tube, gastric contents, and delayed emptying of the stomach. Intuitively, placing the tip of the feeding tube into the intestine rather than the stomach should reduce aspiration, and the Canadian clinical practice guidelines recommend postpyloric feeding. On the other hand, a meta-analysis comparing gastric and postpyloric feeding did not show any significant difference in the incidence of pneumonia between patients fed into the stomach and those fed beyond the pylorus. Although enteral feeding is widely practiced as the route of choice, in a study of 103 patients admitted to an ICU who were observed prospectively for the development of nosocomial pneumonia, there was evidence that feeding contributed to pneumonia. In that study, a multivariate analysis concluded that continuous enteral feeding, but not the nasogastric tube, was an independent risk factor for nosocomial pneumonia and patients who developed pneumonia had a significantly higher mortality of 43.5% compared to 18.8% for those who did not develop pneumonia. Clearly, more studies need to be done to determine the best approach to prevent pneumonia.

The use of prokinetics is another way of promoting gastric emptying. In a placebo controlled randomized trial of 305 patients receiving enteral feeding, giving metoclopramide did not reduce the incidence of pneumonia. Erythromycin, a motilin receptor agonist, is another powerful prokinetic agent. In a randomized controlled trial the benefit of erythromycin was questionable. There was no difference in the rate of pneumonia between the placebo and erythromycin-treated patients. The previous studies unfortunately involved small numbers of patients, and there is a need for larger trials of small bowel feeding and prokinetics to establish their role in promoting enteral feeding and reducing the risk of aspiration.

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Nutritional Support: Adults, Enteral

A.K. Fischer , ... G.E. Mullin , in Encyclopedia of Human Nutrition (Third Edition), 2013

Adults, Enteral

Definition

Enteral feeding is a method of providing nutrients directly into the gastrointestinal (GI) tract when a person cannot receive food orally. It is used in patients who have an adequate functional GI tract and can digest and absorb food but in whom oral intake is inadequate to maintain or restore optimal nutritional status. Also known as tube feeding, enteral nutrition (EN) delivers nutrients directly to the stomach or intestines through a thin flexible tube. It is administered through a nasogastric tube placed via the nose, or a percutaneous tube placed into the stomach (gastrostomy) or the small intestine (jejunostomy). EN is generally considered safer and the preferred method of delivering nutritional support over parenteral nutrition. In this article, the use of enteral feeding is reviewed.

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LUNG DISEASES

A. MacDonald , in Encyclopedia of Human Nutrition (Second Edition), 2005

Enteral nutrition

Enteral feeding is more commonly used in teenagers and adults, reflecting their deterioration in nutritional status. It is considered if the patient is less than 85% expected weight for height, the patient's weight has declined by two centile positions, the patient has failed to gain weight over a 6-month period, or the patient has a BMI less than 19. Enteral feeding is associated with improvements in body fat, height, lean body mass, muscle mass, increased total body nitrogen, improved strength, and development of secondary sexual characteristics. To produce lasting benefit, numerous studies have demonstrated that enteral feeding should be continued long term. The choice of route used is influenced by the duration of feeding and the preference of the patient and family, but gastrostomies, sited by endoscopic placement, are usually chosen for long-term feeding ( Table 4 ).

Table 4. Advantages and disadvantages of enteral feeding routes

Method Advantages Disadvantages
Nasogastric Short-term feeding Tube reinsertion may be
Distressing to patient/caregiver/nurse
Easily removed
Risk of aspiration
Discomfort to nasopharynx
Psychosocial implications
Nasojejunal Less risk of aspiration Difficulty of insertion
Short-term feeding Radiographic check of position
Easily removed
Risk of perforation
Abdominal pain and diarrhoea unless continuous infusion of feed
Discomfort in nasopharynx
Reflux of bile is facilitated
Gastrostomy Cosmetically more acceptable Increase reflux if present
Long-term feeding Local skin irritation
Infection
Granulation tissue
Leakage
Gastric distension
Stoma closes within a few hours if accidentally removed
Jejunostomy Reduced risk of aspiration Surgical/radiology procedure
Long-term feeding Risk of perforation
Must be constant infusion of feed
Bacterial overgrowth
Dumping syndrome can occur

Adapted from MacDonald A, Holden C, and Johnston T (2001) Paediatric enteral nutrition. In Payne-James J, Grimble G, and Silk D (eds.) Artificial Nutrition Support in Clinical Practice, pp. 347–366. London: Greenwich Medical Media.

It is common practice to give enteral feeding for 8–10   h overnight, with at least 40–50% of the estimated energy requirement given via the feed. Most patients tolerate an energy-dense polymeric feed providing at least 1.5   kcal/ml with additional pancreatic enzymes. However, there is some support for the use of chemically defined elemental or short-chain peptide feeds. These are generally low in fat and are administered without the use of pancreatic enzymes, although there is little evidence to support this practice and it is disputed by some. Monitoring for glucose intolerance is important. Patients receiving supplemental feeds who demonstrate repeated blood sugar levels higher than 11.1   mmol/l during the feed may benefit from insulin given before the feed.

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Nutrition in the Hospitalized Elderly

Wafaa Mostafa Abd-El-Gawad , Doha Rasheedy , in Molecular Basis of Nutrition and Aging, 2016

Enteral Nutrition

Enteral feeding is used to meet the nutritional needs of patients with a functional gastrointestinal tract but who are unable to safely swallow [70]. It is usually started through a nasogastric tube, however, in elderly patients in whom EN is anticipated for longer than 4 weeks, placement of a percutaneous endoscopic gastrostomy tube is recommended [71].

Enteral feeding is always favored over parenteral nutrition (PN) because the failure to maintain normal oral nutrition is associated with immunological changes and impairment of the gut associated lymphatic system (GALT), which in turn makes the intestine a source of activated cells and pro-inflammatory stimulants during gut starvation through lymphatic drainage [72].

In addition, EN carried lower risk of infection with increased secretory IgA, minimal or no risk of refeeding syndrome, mechanical and metabolic derangement, and it is more cost effective compared to PN [72]. The data regarding effect of EN on survival, length of hospital stay, and QOL remain conflicting [71].

The EN provided by the gastric route is more physiologic, is easier to administer (ie, bolus feeding with no need for delivery devices for continuous administration), and allows for a larger volume and higher osmotic load than the small intestine. While, postpyloric feeding may be beneficial in patients at high risk of aspiration, severe esophagitis, gastric dysmotility or obstruction, recurrent emesis, and pancreatitis [70].

The complications of EN in elderly are similar to those in other age groups [71]. The most prevalent complications related to enteral feeding are abdominal bloating, vomiting, high gastric residual volume, and increased risk of aspiration especially in mechanically ventilated patients [72].

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Enteral nutritional support

Stanley L. Marks , in Oral and Maxillofacial Surgery in Dogs and Cats, 2012

Rationale for enteral nutritional support

Enteral feeding is indicated in patients who cannot ingest adequate amounts of calories, but have sufficient gastrointestinal function to allow digestion and absorption of feeding solutions delivered into the gastrointestinal tract via an enteral feeding device. The rationale for prescribing enteral nutrition rather than parenteral nutrition (TPN) is based on the superior maintenance of intestinal structure and function, safety of administration, and reduced cost of enteral alimentation. The average daily cost of TPN for maintaining the caloric requirements of a 20-kg dog at the University of California, Davis, Veterinary Medical Teaching Hospital, is US$50.00 (excluding catheter costs) compared with US$5.00 for a commercial liquid enteral formula (Hill's Prescription diet® a/d, Hill's Pet Nutrition, Topeka, KS), and US$3.00 for a commercial canned diet (Hill's Prescription diet® canine p/d, Hill's Pet Nutrition, Topeka, KS). The most important stimulus for mucosal cell proliferation is the direct presence of nutrients in the intestinal lumen. Bowel rest due to starvation or administration of TPN leads to villous atrophy, increased intestinal permeability, and a reduction in intestinal disaccharidase activities. 1,2 Prolonged fasting in the stressed, critically ill patient can lead to intestinal barrier failure and increased permeability to bacteria and endotoxins.

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Enteral and Parenteral Nutrition

Stanley L. Marks , in Canine and Feline Gastroenterology, 2013

Rationale for Enteral Nutritional Support

Enteral feeding is indicated for animals unable to ingest adequate amounts of calories, but that have sufficient gastrointestinal function to allow digestion and absorption of feeding solutions delivered into the gastrointestinal tract via an enteral feeding device. The rationale for prescribing enteral nutrition rather than parenteral nutrition (PN) is based on the superior maintenance of intestinal structure and function, 2 reduced infection rates, 3 and reduced cost of enteral alimentation. The average daily cost of total parenteral nutrition (TPN), hereafter referred to as central parenteral nutrition (CPN), for maintaining the caloric requirements of a 20-kg dog at the University of California, Davis, Veterinary Medical Teaching Hospital, is approximately five to 30 times greater (excluding catheter costs) than the cost of a commercial liquid enteral formula, and 60 times greater than the cost of a commercial canned diet for intestinal disorders. The most important stimulus for mucosal cell proliferation is the direct presence of nutrients in the intestinal lumen. 4 Bowel rest as a consequence of starvation or administration of CPN leads to villous atrophy, 5 increased intestinal permeability, and a reduction in intestinal disaccharidase activities. 6 Prolonged fasting in the stressed, critically ill animal can lead to intestinal barrier failure and increased permeability to bacteria and endotoxins. However, enteral nutrition may have shortcomings including underfeeding, perceived intolerance, aspiration, access-related complications, and diarrhea. 7

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Feeding management pre- and post-surgery

Tim Mair , in Equine Applied and Clinical Nutrition, 2013

Intestinal surgery in foals

Enteral feeding of foals with colic or abdominal distension is contraindicated and intravenous fluid and dextrose therapy is required to prevent fluid and electrolyte imbalances, and hypoglycemia. Nursing from the mare can be prevented by separating the mare and foal by a partition or by the use of a muzzle. Following intestinal surgery, similar considerations to the adult are needed to determine the optimum time to reintroduce oral feeding, but in most cases with intestinal distension, enteritis or intestinal resection, enteral rest for at least 48 hours is recommended; earlier return to oral feeding may induce ileus. Parenteral nutritional support is required if enteral rest for longer than 48 hours is necessary. When feeding is reintroduced, approximately 100 ml of water or dextrose solution is administered every 2 hours. The volume offered is slowly increased until a volume of 350–400 ml is administered. Once this volume is achieved and assuming that the foal tolerates this volume, a 50 : 50 mixture of water and milk/milk replacer is given. The strength of the milk solution is slowly increased over several feeds until full strength milk/milk replacer is used.

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Enteral Nutrition

Laura Eirmann DVM, DACVN , Kathryn E. Michel DVM, MS, DACVN , in Small Animal Critical Care Medicine (Second Edition), 2015

Oral Intake Versus Enteral Feeding Device

When enteral feeding is appropriate, the clinician selects the mode of nutrient delivery, sets a caloric goal, and chooses an appropriate diet. Enteral feeding as far proximal in the GI tract as the patient can tolerate is preferred. Voluntary oral intake has distinct advantages. It requires no special equipment or techniques and allows the owner to participate in patient care. If the oral route is selected, the clinician must write specific feeding orders. The technical staff offers the amount written on the feeding orders and records the amount consumed. The clinician then determines if the nutrition goal was met. If intake does not meet the goal, the clinician reassesses the patient, diet, and environment. The clinician may change the diet (e.g., more palatable diet, warming the food) or change the environment (e.g., quieter ward, owner feeding the pet). Syringe feeding a liquid or blenderized pet food may be attempted for 1 to 2 days but often becomes too stressful and time consuming. If the patient shows any signs of nausea, oral feeding should be discontinued immediately, because this can lead to a learned food aversion. Medication to ameliorate nausea and an alternative feeding method should be considered. Appetite stimulants such as cyproheptadine or mirtazapine may be considered after careful patient assessment. The effectiveness of the treatment must be closely monitored by recording daily caloric intake and any possible side effects. Pharmacologic stimulation of appetite does not replace the need for daily nutritional assessment nor negate consideration of enteral feeding devices. If adequate intake is not achieved or side effects occur, the plan must be revised to meet the patient's nutritional needs.

An enteral feeding tube removes the variable of voluntary intake. The technical staff delivers a prescribed amount of a specific diet via the feeding tube according to orders written by the veterinarian. These tubes are well tolerated by veterinary patients and, when anticipated, can be placed while the patient is sedated or anesthetized for a diagnostic or therapeutic procedure. A retrospective owner survey concluded that owners were comfortable managing their cats at home with esophagostomy and percutaneous endoscopic gastrostomy tubes. 8 Enteral feeding device placement usually requires sedation or anesthesia and technical skill. Technicians and owners must be taught how to use feeding devices and monitor for complications. Table 129-1 outlines advantages and disadvantages of the various forms of enteral access used in veterinary patients.

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