ENTERAL NUTRITION

Nutrition plays an important role in the prevention and management of many diseases. None today would challenge the concept that nutritional support is an integral and essential element in the care of the patient who is critically ill nutritionally, depleted or both. Patients unable to consume necessary nutrients orally require alternative form of nutritional support. Chronic illness is associated with many complications such as anorexia, hypermetabolism, malabsorption, atrophy of muscles, liver, kidney, gastrointestinal tract heart, impaired cell mediated immunity, susceptibility to infection, poor wound healing, anemia, death. Hence it is important to correct caloric and nutrient deficiencies whenever possible. By definition the term enteral means "within or by the way of the gastrointestinal (GI) tract." In common practice however, commercially available liquid nutritional supplements are generally referred to as " oral supplements and " enteral feeding" and "tube feeding" are used interchangeably. History of enteral feeding dates back to 18th century. In 1790 John Hunter cured a case of paralysis for which had fed through a tube made of whalebone. Stengel and Ravdin used Nesoenteric route for the first time in 1939. The feeding was introduced through the nose and advanced into the jejunum for Post-operative nutritional support. There are primarily two routes of access for aggressive nutritional support i.e. enteral and parenteral. The majority of patients are given oral diets to provide for nutrient needs. When patient does not consume adequate nutrients it is supplied by increasing the amount of food or by giving snacks in between meals. Liquid supplementation is often useful, because food is easier to drink than to eat. Psychologically liquid seem to be less filling, and they are much easier to digest for debilitated patients to handle. Selection of feeding can be done stepwise. First step regular or modified diet, 2.Regular or modified diet and supplements. 3. Tube feeding.

In-patients where the gastrointestinal tract (GI) cannot be used, nutrition should be provided by the parenterally. The enteral route partly or wholly must feed patients with a gastrointestinal tract functional. Frequently it is quoted "when the gut works and can be used safely use it".

Enteral feeding is the method of nutrient solutions fed into gastrointestinal (GI) tract through a tube. Enteral nutrition is the optimal method for meeting nutritional needs of a child who has a functioning gut and is unable or unwilling to achieve oral intake.

    1. The development of simple and low risk procedures for placement of tubes in GI tract particularly percutaneous endoscopic gastrostomies and jejunostomies.
    2. The availability of wide variety of commercial enteral feeding formulas.
    3. Enteral nutrition is generally less expensive than parenteral nutrition.

Goals of feeding

    1. Selection of an appropriate formula
    2. Formula delivery
    3. Indications of nutritional status

Indications

Specific conditions for which nutrition indicated for adults and children shown in table 1

Table 1. Indications for nasoenteric Tube feeding for adults

Neurological indications:

    1. Severe Head injuries
    2. Cerebrovascular accidents
    3. Coma due to any cause
    4. Neoplasms: Advanced primary and secondary intracranial tumors
    5. Dysphagia associated with neurological disorders

Hypermetabolism:

1. Postoperative major surgery

2. Sepsis

3. Trauma Burns Organ transplant acquired immune deficiency syndrome

Surgical indications:

    1. Facial and jaw surgeries
    2. Head & Neck surgeries
    3. Oropharyngeal surgeries
    4. Pharyngoesophageal surgeries
    5. Polytrauma associated with extensive abdominal surgeries
    6. Patients with burns for surgeries unable to take oral nutrition
    7. Surgery complicated with sepsis

Gastrointestinal (GI) disease

    1. Short-bowel syndrome (if absorptive capacity of remaining bowel is sufficient e.g. approximately a minimum of 100 cm jejunal and 150 cm of ileal length of functioning small bowel with ileocecal value intact.
    2. Inflammatory bowel disease
    3. Minimal GI tract fistula output ( less than 500mL/d)
    4. Pancreatitis
    5. Esophageal obstruction
    6. Malabsorption
    7. Fistulas

Cancer

    1. Oral malignancies
    2. Oropharyngeal malignancies
    3. Nasopharyngeal malignancies
    4. Head and neck malignancies
    5. Esophageal malignancies
    6. Gastric malignancies
    7. Chemotherapy
    8. Radiotherapy

Resistance to oral intake

    1. Anorexia
    2. Dysphagia
    3. Severe depression

Malnutrition

    1. Protein energy malnutrition with inadequate oral intake for at least 5 days
    2. Malnutrition preoperatively and postoperatively
    3. Malnutrition in cancer patients
    4. Malnutrition in-patients with Acquired Immune Deficiency Syndrome (AIDS) unable to take oral nutrition.
    5. Malnutrition in debilitated aged patients

Organ system failure:

    1. Respiratory failure
    2. Renal failure
    3. Cardiac failure
    4. Central nervous system failure
    5. Hepatic failure
    6. Multiple organ system failure

Transition from parenteral nutrition

For children

  1. Malnutrition
  2. Malabsorption
  3. Hypermetabolism
  4. Failure to thrive
  5. Prematurity
  6. Disorders of absorption, digestion, excretion, utilization, or storage of nutrients

Contraindications:

  1. Malfunctioning of GI tract or conditions requiring extended bowel rest

  1. Harm may exceed benefit for incompetent patients with end-stage illness, minimal levels of consciousness, and lack of advance directives, whose anticipated benefits may be uncertain or short-term; is likely against the patient’s best interests.

Advantages of enteral feeding

  1. Provides good nutritional care plan
  2. Nourishing child who can not take adequate nutrients orally
  3. Helps family and health care professionals to see enteral alimentation as positive and optimal way rather than a punitive and optimal way of nourishing the malnourished child.

Nutritional requirements

  1. The recommended dietary allowances serve as initial guidelines in the selection and modification of a formula

  1. The disease process itself indicates whether the requirements are changed
  2. Drug induced nutritional deficiencies may develop from long-term use of medication that affects

  1. Feeding tube
  2. The small-caliber tubing requires a finely dispersed product with low viscosity whereas the gastrostomy tube can accommodate blenderized feed

  3. Fluid requirement

Enteral formulas

Selection of an appropriate enteral formula requires assessment of patient’s digestive and absorptive capacity as well as the knowledge of the substrate source and form.

  1. Protein components:

Components of protein are intact protein (larger molecular weight protein), partially hydrolyzed protein (protein enzymatically hydrolyzed into shorter polypeptide fragments such as oligopeptide), dipeptides and tripeptides (type of partially hydrolyzed proteins to di and tri-peptide fragment.

    1. Protein quality attributed to amino acid profile: an amino acids of at least 40% amino acids as essential amino acids is suggested for anabolism.
    2. Predominant sources of protein include soy and casein.

  1. Carbohydrate components

Components of carbohydrate are starch, glucose polymers (derived from partially hydrolyzed corn starch), disaccharide (sucrose: glucose – fructose; maltose (glucose – glucose; lactose: glucose – galactose), monosaccharides (glucose: dextrose; fructose)

    1. Primary differences in carbohydrate components are related to the form and concentration of carbohydrate
    2. The most predominant form of carbohydrate found in enteral formula is hydrolyzed cornstarch or maltodextrin

  1. Fat components

Components of fat are polyunsaturated fatty acids (PUFA), medium chain triglycerides (MCT) and saturated fatty acids (SFA)

    1. Fat enhances palatability and flavor of formula
    2. Vegetable oil contains variable amount of essential fatty acids (EFA).
    3. Suggested EFA intake specially linoleic acid is 3% to 4% total calorie needs.
    4. Sources of fat commonly found in formulas include a variety of vegetable oils

  1. Fiber components

Component of fiber is insoluble (cellulose, noncellulose: hemicellulose), or soluble fiber (pectin, mucilage, algal polysaccharide, gum).

    1. Content of fiber-supplemented formula ranges from 5 to 14 g of fiber per liter.
    2. Recommended intake of dietary fiber is approximately 20 to25 g / day
    3. Preliminary studies have shown that fiber intake of less than 30 g / day did not seem to impair vitamin, mineral or drug bioavailability in the gut.
    4. Most predominantly used from of fiber in enteral formulas is soy polysaccharide.

  1. Water

    1. Quantity water in the enteral formulas is often described as water content or moisture content
    2. Quantity of water ( frequently reported in milliliters of water per 1000 ml of formula or milliliters of water per liter of formula)
    3. Most of enteral formulas contain water in the general range of 690 to 860 ml per 1000ml of enteral formula. Standard infant formulas are 0.67 calories/cc. Whereas adult formulas are either 1 calorie/cc or 1.5 to 2.0 calories/cc

Table 6 water content of enteral formula for adults

Caloric density (kcal/ml formula)

Water content (ml/1000 ml formula)

Water content

1.0 – 1.2

800-860

80-86

1.5

760-780

76-78

2.0

690-710

69-71

  1. Vitamin and minerals

    1. Most nutritionally complete commercial formulas contain adequate vitamin and minerals when a sufficient volume of formula to meet energy and macronutrient needs is provided.
    2. Some disease specific formulas are nutritionally incomplete in relation to vitamin and mineral content
    3. Liquid vitamins and mineral supplements may be indicated for patients receiving nutritionally incomplete or diluted formulas for prolonged periods
    4. Fat-soluble vitamins such as vitamin K may be indicated for patients with fat absorption or for patients with vitamin K deficiency; vitamin K deficiency is rare in as much as vitamin K is synthesized by intestinal flora, and most commercial formulas includes vitamin K.

Physical characteristic of enteral formula

  1. Osmolality

    1. Definition: function of size and quantity of ionic and molecular particles (protein, carbohydrate, electrolytes, and minerals ) within a given volume

    1. Factors affecting osmolality are:

    1. Formulas with greater hydrolyzed nutrient components have proportionately higher osmolalities.
    2. Effect of osmolality on GI tolerance: gastric retention, abdominal distention, diarrhea, nausea, and vomiting.

2. pH

    1. Gastric motility is reportedly slowed with solution lower than pH 3.5.
    2. The pH level of most commercial formulas is > 3.5.

    1. Calorie and nutrient density : gastric emptying time may be slowed by formulas containing higher calorie-nutrient density

Classification of formulas

  1. Polymeric formulas:

  1. Most of patients who are critically ill may be enterally fed with polymeric formulas.
  2. Nitrogen balance has been reported to be similar for patient with normal digestive and absorptive capacity who were fed intact protein, partially hydrolyzed protein, and amino acids with approximately the same amino acid profiles.
  3. Intrajejunal digestion, nutrient absorption, and nitrogen balance have been reported to be similar between intact protein and polymeric formulas compared with partially hydrolyzed (small peptides and amino acids) formulas in jejunal feedings in under nourished patients.

  1. Partially hydrolyzed formulas:

  1. Characteristics:

  1. Composition may vary in free amino acids and peptides, type and quantity of fat, content of carbohydrate content.
  2. Indicated for patients with partial digestive and absorptive capacity; patients with resolved acute illness might be capable of transition form partially hydrolyzed formulas to polymeric formulas.

  1. Disease-specific formulas: some formulas are designed for specific organ dysfunction and some are for metabolic stress. Efficacy of the disease specific formulas is controversial
  2. Modular formulas:

  1. One purpose for using modular formulas is supplemental use

  1. Another advantage is that it can be de novo formulated for individualized designed of nutrient formula to meet specific nutrient needs of an individual.
  2. Advantages of de novo enteral formulation include

  1. Disadvantages of de novo formula include

Determining an optimal access route for enteral nutrition depends upon

    1. Anticipated duration of enteral feeding
    2. Risk of pulmonary aspiration, e.g.. In patients with diminished mental status or esophageal reflux

Guidelines for selection of product:

Substrate source individual requirements and ability to tolerate various sources of intact or elemental carbohydrate protein and fiber.

Calorie concentration The calorie-to –volume ratio will affect the volume required to meet nutritional requirements. Increasing the calorie-to-volume ratio will affect the osmolality of the solution.

Available feeding equipment – The size of the feeding tube, drip chamber, and availability of pumps may affect the choice of solution. Blenderized feeding and those containing soy polysaccharide fiber usually require pumps for the infusion through smaller bore tubes due to higher viscosity.

1. Determine total volume for adult man per day

a] Continuous feedings: example- formula to run at 75 cc/hr.

75 cc/hr X 24hrs = 1800 cc or 1.8 liters

b] Intermittent feeding: Example – formula to be given in volume of

400cc 5 times a day i.e. 400cc X 5 = 2liters.

    1. Determine the calorie content of the formula by multiplying the total volume (cc) calorie/cc of the formula.
    2. Example 1800 cc X 1.06 kcal/cc = 1908

    3. Determine the protein content either per cc or per liter. This can be calculated by multiplying the total volume in liters by protein per liters or per cc.
    4. Example 1.8 liters X 37 g protein per liter = 67 g protein.

      Or 1.8 liters X 0.037 g protein per cc = 67 g protein

    5. Determine the actual calories and protein provided by multiplying the calories and protein per liter by the strength of formula.

1 /4 strength = 0.25 1/2 strength = 0.5 3 /4 strength = 0.75

1/3 strength = 0.33 2/3 strength = 0.67 full strength = 1.0

2. Method of estimating fluid needs for children

100 cc / kg for the first 10 kg

50 cc / kg for the next 10 kg over 10 kg

20 cc / kg for the number of kg over 20 kg

Example: child weighing 35 kg

First 10 kg = 100 X 10 =1000

Next 10 kg = 50 X 10 = 500

Remaining 15 kg = 15 X 20 = 300

Total fluid requirement = 1800 cc

(Final fluid requirement will be depend upon disease condition)

Initiation of feeding

    1. Prior to initiating enteral feeds, tube placement must be verified.
    2. Placement can be confirmed by the aspiration of gastric contents.

    1. It is recommended that a small syringe (10 to 30 cc) be used when checking small bore tubes to prevent exerting negative pressure and collapsing the tube.
    2. If gastric content can not be aspirated through the tube, then radiographic confirmation of tube location should be done.

    1. Isotonic solution can be initiated full strength at a rate of 25 to 50 cc per hour and advanced every 12 to 24 hours until the desired rate is achieved.
    2. If intolerance develops at any time appropriate adjustment should be made.
    3. Rate of the feeding is advanced to desired volume and then strength of the formula is gradually increased until calorie and protein needs are achieved.
    4. Strength and rate should not be advanced concurrently.

Determining the method for the tube feeding administration

  1. The method selected depend upon

    1. Central access route
    2. Stability of the patient (whether patient is critically ill or not.)
    3. Gastric emptying rate
    4. GI tolerance of tube feeding
    5. Type of formula use
    6. Calorie and protein needs
    7. Ease of administration
    8. Patients mobility.

  1. The Feeds are given either by continuous drip, intermittent infusions, and bolus feed.

    1. Continuous drip- Tube feedings are administered at constant, steady rate usually over 24 hrs of period. Use of an infusion pump is recommended, as accuracy of volume delivered is assured. However most enteral feeding is administered by gravity of force.
    2. Intermittent infusions- Tube feeds are administered at specific intervals through out the day. The volume of desired feeding is divided into equal portion and been fed 4 to 6 hourly per day. The feedings are usually given by gravity drip over period of 30 min. to 1 hour.
    3. Bolus feed – Rapid installation of feeding into GI tract by syringe or funnel. The majority of patients tolerate this method of feed.

For optimal results of enteral feeding the following points to be considered:

Temperature:

Bacterial contamination:

Prevention of aspiration:

Patency:

Monitoring:

  1. Complications associated with enteral tube feeding may be prevented and managed with appropriate monitoring.

    1. Monitoring schedules are diversified because of patients stability, institutional protocol, and feeding duration.

  1. Prevention of mechanical, GI, and infectious complications of tube feeding
  2. Total quality care of tube feeding patients requires interdisciplinary team management.

Home blend formulas

Occasionally patient requests or is required to prepare tube feeding at home. Though this is possible and does have some benefits, there are some significant points to be consider when home blend formulas are prescribe to the patient. The table no will show the advantages and disadvantages of home blend formulas.

Advantages and Disadvantages of home blenderized tube feeding

Advantages

Disadvantages

Family can take an active part in food preparation for patient

Less costly

Commercially prepared products can be 10% to 50% more expensive

Cost of commercial products is not always reimbursable.

Payment is depend upon necessity of use as dictated by disease process

Increased amount of fiber can be provided

Sense of " being different " is lessened since the patient can enjoy the same table food as his or her family

 

 

Manipulation of individual nutrients is easier in blenderized feedings than with commercial products

Unpleasant taste from eructations is less likely to occur

Blenderized feeding require more time and energy to prepare than commercial products

Special equipment is needed i.e. blender or food processor, measuring utensils, access to refrigeration etc

 

Special care must be taken to liquefy the contents of the blender completely, as food particles can clog the feeding tube

 

Feeding must be prepared daily

Daily ingredient selection should be carefully made to ensure nutrition adequacy of diet.

May need vitamin and mineral supplementation

Extra amount of blenderized feed must be kept refrigerated and must slightly warmed before feeding.

Higher incidence of bacterial contamination may occur.

Clean food preparation technique must be emphasized

 

Blenderized feeding are difficult to sue if the patient is away from home

The home tube feeding recipes is a teaching tool for use by either the patient or the primary caretaker. The content of feeding are determined by the dietician to provide the requirement of the nutrients such as protein, calories, carbohydrate fat, vitamins, minerals and water. The feeding can be prepared either by blender or using hand mixer.

Directions:

  1. Measure all ingredients accurately. Pour into large mixing bowl and stir contents to combine.

  1. If mixture is thick, thin with water until the desire consistency is achieved.
  2. Pour formula into individual jars. Cover and refrigerate immediately. Discard any unused formula within 24 hours
  3. Take individual serving out one hour before needed and allow it to warm to room temperature before use. Always keep it covered.
  4. The patient/caretaker should follow the direction given to him regarding feeding

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