University Hospital and Medical Faculty of Charles University
Enteral nutrition allows the delivery of nutrients in a natural way, stimulates immunity, reduces overgrowth of intestinal microflora, reduces intestinal permeability and has a positive influence on intestinal peristalsis. The enteral nutrition formulae are nutritionally defined low-osmolar and usually low-residue solutions that do not contain lactose and gluten.
A number of formulae are taste-adjusted, which allows continuous drinking of the nutrition during the whole day (sipping, drink feeding). In diabetic patients, frequent monitoring of glycaemia and ingested saccharides in food and artificial nutrition enable diabetes treatment modification with inclination to insulin administration for its anabolic effect.
The aims of enteral nutrition are:
- Provision of sufficient energy input in order to influence the nutritional state of the patient, support functions of gastrointestinal tract and overcome anatomic or functional deficiencies in the upper gastrointestinal tract. In this case enteral nutrition covers all nutritional needs of the organism.
- Affecting the integrity of gastrointestinal tract. In this case enteral nutrition need not cover the total nutritional needs of the patient.
Indications of enteral nutrition
Enteral nutrition is indicated in patients with malnutrition who cannot or must not eat and drink and/or in patients with digestion and resorption deficiency that practically disables or significantly restricts peroral intake of common food. A summary of the most frequent indications for enteral nutrition is provided in Table 1.
Contraindications of enteral nutrition
Absolute contraindications of enteral nutrition include mechanical obstruction of gastrointestinal tract distally from a stomach, perforation of gastrointestinal tract, paralytic ileus and acute peritonitis. Among relative contraindications from the primary malady and its complications are uncontrollable vomiting, upper intestinal fistulae and defects in intestinal passage. These states represent a reason for postponement of initiation of enteral nutrition or dose reduction.
Ways of administration of enteral nutrition
The nutrition can be administered continually, as a bolus or through continuous delivery with an intermission at night or delivery at night with an intermission during the day when attempting normal food ingestion.
Enteral nutrition can be combined with normal food ingestion (eg, night enteral nutrition, sipping) or with parenteral nutrition (critical state) when the intestine is not able to reabsorb sufficient amount of nutrients in time.(1)
Continuous drinking of nutrition: sipping and drink feeding
It is appropriate to utilise sipping when the patient is not able to consume sufficient amounts of nutrition. It has been proved that oral supplements in the form of sipping increase intake of proteins, energy, minerals and vitamins, and in addition they maintain or even improve the nutritional state of the patients.(1)
Enteral nutrition through a tube
- The nasogastric tube is an elastic tube made of biocompatible plastic material with diameter of CH 6–22 inserted in a stomach. The use of nasogastric tube is temporally limited by the type and material used and is determined by the recommendations of producer.(2,3) When the proposed period of nutritional intervention is longer than 30 days, the access through percutaneous gastrostomy into upper gastrointestinal tract is more appropriate
- The nasojejunal tube differs from nasogastric in length (125–150 cm) and diameter (CH 6–12). The end of nasojejunal tube is usually inserted into proximal jejunum.
- The nasogastro-nasojejunal tube is a double-lumen catheter with one opening leading to jejunum while the other lumen (usually bigger) opens out to a stomach. It is predominantly used for early enteral jejunal nutrition while the gastric opening enables monitoring of residues and their derivation.
- Gastrostomy and jejunostomy provide long-lasting access to upper gastrointestinal tract. It is usually performed using percutaneous method, endoscopic percutaneous gastrostomy (PEG) and endoscopic percutaneous jejunostomy (PEJ).(1)
Systems for administration of enteral nutrition
- A special syringe, usual volume 250 ml, is used for bolus administration of lukewarm enteral nutrition into a stomach. It is not suitable for jejunal application. Prior to every administration of the nutrition it is important to monitor the amount of residues by gastric content aspiration.(4)
- A gravitational system is comprised of a sac or a bottle that are connected to the tube or gastrostomy by an administration set.
- An enteral pump is a device for continuous delivery of enteral nutrition. It usually is equipped with independent power source. It is recommended as standard equipment for outpatient enteral nutrition delivery.
Solutions designated for enteral nutrition
Polymerous or oligomerous nutritionally defined nutritional formulae are composed of peptides, triglycerides and maltodextrin. The solutions have low osmolality and are lactose and gluten-free. Some of them are flavoured and are thus suitable for drinking. A company supply of nutritional formulae is very diverse in energetic dosages (0.8–2 kcal/ml).
The formulae are divided into several groups. Most commonly used are formulae packaged in plastic or paper containers supplied with a straw designed for drinking the nutrition. The feeds designed for enteral nutrition through a tube into stomach are polymerous, and digestive enzymes are thus needed for their digestion. In addition, there are oligomerous formulae for enteral nutrition in the jejunum available on the market. These feeds do not require the presence of digestive enzymes, yet they are quite expensive. There are also formulae enriched with fibre which increase the motility of the gastrointestinal tract. By means of fermentation in the large intestine, short-chain fatty acids arise that serve as an energy source for colonocytes. In recent times, efforts have been made to use modified enteral nutrition as an immunostimulant. Formulae enriched with essential fatty acids, arginine, glutamine, RNA and MTC or omega-3 lipids are being used more and more in patients in critical states and in patients following immunosuppressive treatment.
Enteral nutrition and sipping in diabetic patients
Enteral nutrition in diabetics has certain specificities that arise from the risk of hyperglycaemia, ketoacidosis, hypoglycaemia and fast shift to catabolism upon starvation. The effect of enteral nutrition is modified by the following factors:
- Deterioration of gastric motility (evacuation of a stomach) during hyperglycaemia and diabetic visceral neuropathy.
- Hyperglycaemia associated with glycosuria that leads to abrupt development of protein catabolism, energy loss (glucose) to urine and loss of minerals to urine. The immunocompetence of the organism decreases, and wound healing deteriorates.
- Hypoglycaemia resulting from an inappropriately set treatment algorithm leads to the employment of compensatory mechanisms and subsequent variation in glycaemia and deterioration of the quality of life of the patient.
Enteral nutrition formulae designed for diabetic patients
Diabetic diets are characterised by the effort to decelerate glucose resorption; they thus have a low glycaemic index.(5) Recently, postprandial glycaemia started to be monitored, as a direct relationship between postprandial glycaemia and coronary atherosclerosis has been demonstrated.(6) Postprandial glycaemia depends upon two main factors:(7)
- Individuality of the patient (insulin sensitivity, function of beta-cells, gastrointestinal motility, physical activity, digestion, absorption, utilisation and oxidation of ingested food and diurnal variation of listed parameters).
- Ingested food (amount, state of matter, biological source and speed of polysaccharide digestion, amount of sugars, fats, proteins, fibre, food acidity, manner of food preparation and presence of antinutrients).
The advantages of enteral nutrition utilisation in diabetic patients
- Monitoring of glycaemia: in type 2 diabetics it is acknowledged that division of daily food intake into more doses and utilisation of foodstuffs with low glycaemic index leads to a decrease in postprandial glycaemia, improvement of glycaemic control, reduction of insulinaemia and decrease in level of cholesterol and free fatty acids.(7–9) Continuous supply of saccharides in doses of 15 g of glucose per hour, which corresponds to an intake of 100 kcal of nutrition per hour (see Table 2), can easily be “covered” by continuous insulin infusion or a bolus dose of short-acting insulin four times a day. The insulin treatment is not necessary in a number of type 2 diabetics with adequate energy intake.
- Cholesterol level reduction: enteral nutrition does not contain cholesterol.
- Insulin resistance reduction using continuous saccharide delivery and diet with appropriate caloric content.
Continual drinking of nutrition (sipping in diabetic patients)
Daily intake of 1,500 kcal in sipping corresponds to intake of 200 g of saccharides. Upon commencement of the treatment it is necessary to monitor fasting glycaemia and glycaemia two hours after ingestion of food (postprandially). The content of saccharides in artificial nutrition must be added to the amount of saccharides ingested in normal food. It is practical to realise that ingestion of a cup of enteral nutrition is, in terms of saccharide load, approximately comparable to administration of three cups of milk. The most convenient method is continual delivery of artificial nutrition in dosage of 50–l00 ml per hour. If this regime does not suit the patient, the treatment is transformed to food intake plus sipping in four doses per day. This may be covered by a bolus dose of a short-acting insulin analogue. Insulin is an effective natural anabolic hormone that is preferred to peroral antidiabetic drugs in malnourished patients. Sipping is indicated after meals in order to reduce the impact on sense of taste of the diabetic patient upon consumption of normal food. In type 1 diabetics, sipping is predominantly used during main meals or at times of snacks. In the latter case, short-acting insulin is administered prior to the snack. Replenishment of trace elements, minerals and vitamins, together with energy and protein intake, often leads to improvement of quality of life, riddance of depression and improvement in compliance, which then positively manifests in improvement of glycaemic control.
Enteral nutrition designed for diabetic patients
Enteral nutrition formulae designed for diabetics have recently emerged. These formulae contain less energy and less glucose. They are enriched with amino acids that can stimulate insulin production. Glucose (maltodextrin) is replaced by more slowly metabolised sugars in order to reduce glycaemic index.
At present, enteral nutrition represents a basic means for securing artificial nutrition in patients with malnutrition caused by various diseases. Advances in technical equipment, tubes, administration sets and pumps, as well as development of various nutrition formulae allow its wide utilisation. Enteral nutrition, in comparison with parenteral nutrition, can be realised more easily; it is accompanied by smaller incidence of complications, it is cheaper, and it leads to shortening of hospitalisation.(2,10) Distinct algorithms have been developed for indication of the enteral nutrition in intensive care(11,12) (ESICM statement 1998, ESPEN Guidelines on Enteral Nutrition 2006 ) and in common clinical practice (ESPEN Guidelines on Enteral Nutrition 2006).(12)
- Silk BA. Enteral diet choices and formulations. In: Artificial nutrition support in clinical practice. Great Britain: Edward Arnold; 1995.
- Raff MH, et al. A technique for positioning nasoenteral feeding tubes. JPEN 1987;11:210-3.
- Ugo PJ, et al. Bedside postpyloric placement of weighted feeding tubes. Nutr Clin Pract 1992;7:284-7.
- McClave SA, et al. Use of residual volume as a marker for enteral feeding intolerance: prospective blinded comparison with physical examination and radiographic findings. JPEN 1992;16:99-105.
- Hofman Z, et al. The Glycemic index of standard and diabetes-specific enteral formulas. Asia Pac J Clin Nutr 2006;15:412-7.
- The DECODE study group. Glucose tolerance and mortality: comparison of WHO and American Diabetes Association diagnostic criteria. Lancet 1999;354:617-21.
- Jenkins DJ, et al. Relationship between rate of digestion of foods and post-prandial glycaemia. Diabetologia 1982;35:450-5.
- Edelstein SL, et al. Increased meal frequency associated with decreased cholesterol concentrations. Am J Clin Nutr 1992;55:664-9.
- Jenkins DJ, et al. Metabolic effects of reducing rate of glucose ingestion by single bolus versus continuous sipping. Diabetes 1990;39:775-81.
- Payne-James J, et al. Artificial Nutrition Support in Clinical Practice. London: Edward Arnold; 1995.
- ESICM statement. Working group on nutrition and metabolism. Intensive Care Med 1998;24:848-59.
- ESPEN Guidelines on Enteral Nutrition. Clinical Nutrition 2007;25:177-360.
Supported by Grant of Ministry of Education, Charles University, Prague, Czech Republic CEZ: MSM0021620814.