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.
- The choice of nutritional supplement depends on the degree
of inability to meet nutritional needs by diet alone, presence or absence
of dysphagia, taste preference or sensitivity to taste fatigue, availability
of labor and resource for preparation or presence of other safety and cost
concern, degree of tolerance to lactose, sucrose or glucose or other dietary
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.
- The use of enteral feeding is increasing because of
- The development of simple and low risk procedures for placement
of tubes in GI tract particularly percutaneous endoscopic gastrostomies
- The availability of wide variety of commercial enteral
- Enteral nutrition is generally less expensive than parenteral
- It is important to realize that enteral and parenteral
nutritional supports should not be viewed, as substitutes for each other
as both these methods are complementary rather than competitive.
Goals of feeding
- Selection of an appropriate formula
- Formula delivery
- Indications of nutritional status
- Signs of feeding intolerance
Specific conditions for which nutrition indicated
for adults and children shown in table 1
Table 1. Indications for nasoenteric Tube
feeding for adults
- Severe Head injuries
- Cerebrovascular accidents
- Coma due to any cause
- Neoplasms: Advanced primary and secondary intracranial
- Dysphagia associated with neurological disorders
1. Postoperative major surgery
3. Trauma Burns Organ transplant acquired immune
- Facial and jaw surgeries
- Head & Neck surgeries
- Oropharyngeal surgeries
- Pharyngoesophageal surgeries
- Polytrauma associated with extensive abdominal surgeries
- Patients with burns for surgeries unable to take oral nutrition
- Surgery complicated with sepsis
Gastrointestinal (GI) disease
- 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.
- Inflammatory bowel disease
- Minimal GI tract fistula output ( less than 500mL/d)
- Esophageal obstruction
- Oral malignancies
- Oropharyngeal malignancies
- Nasopharyngeal malignancies
- Head and neck malignancies
- Esophageal malignancies
- Gastric malignancies
Resistance to oral intake
- Severe depression
- Protein energy malnutrition with inadequate oral intake for at least 5
- Malnutrition preoperatively and postoperatively
- Malnutrition in cancer patients
- Malnutrition in-patients with Acquired Immune Deficiency Syndrome (AIDS)
unable to take oral nutrition.
- Malnutrition in debilitated aged patients
Organ system failure:
- Respiratory failure
- Renal failure
- Cardiac failure
- Central nervous system failure
- Hepatic failure
- Multiple organ system failure
Transition from parenteral nutrition
- Failure to thrive
- Disorders of absorption, digestion, excretion, utilization,
or storage of nutrients
- Malfunctioning of GI tract or conditions requiring extended
- Insufficient absorptive capacity of intestinal tract e.g.
short-bowel syndrome ( intestinal span suggested for sufficient absorption
- Mechanical obstruction of GI tract
- Prolonged ileus
- Severe GI hemorrhage
- Severe diarrhea
- Intractable vomiting
- High output GI tract fistula (> 500 ml/ day)
- Severe enterocolitis
- 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
- Provides good nutritional care plan
- Nourishing child who can not take adequate nutrients orally
- 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.
- The recommended dietary allowances serve as initial guidelines
in the selection and modification of a formula
- All nutrients of the final formula should be calculated
and compared with RDA for age or for the developmentally delayed child
for height age
- Vitamin mineral supplementation may be needed
- The disease process itself indicates whether the requirements
- Drug induced nutritional deficiencies may develop from long-term
use of medication that affects
- nutrient function and metabolism
- decrease nutrient absorption or synthesis
- Feeding tube
The small-caliber tubing requires a finely
dispersed product with low viscosity whereas the gastrostomy tube can accommodate
- Fluid requirement
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.
- 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.
- Protein quality attributed to amino acid profile: an amino
acids of at least 40% amino acids as essential amino acids is suggested
- Predominant sources of protein include soy and casein.
- 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)
- Primary differences in carbohydrate components are related
to the form and concentration of carbohydrate
- The most predominant form of carbohydrate found in enteral
formula is hydrolyzed cornstarch or maltodextrin
- Fat components
Components of fat are polyunsaturated fatty
acids (PUFA), medium chain triglycerides (MCT) and saturated fatty acids
- Fat enhances palatability and flavor of formula
- Vegetable oil contains variable amount of essential fatty
- Suggested EFA intake specially linoleic acid is 3% to 4%
total calorie needs.
- Sources of fat commonly found in formulas include a variety
of vegetable oils
- Fiber components
Component of fiber is insoluble
(cellulose, noncellulose: hemicellulose), or soluble fiber (pectin, mucilage,
algal polysaccharide, gum).
- Content of fiber-supplemented formula ranges from 5 to
14 g of fiber per liter.
- Recommended intake of dietary fiber is approximately 20
to25 g / day
- 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.
- Most predominantly used from of fiber in enteral formulas
is soy polysaccharide.
- Quantity water in the enteral formulas is often described
as water content or moisture content
- Quantity of water ( frequently reported in milliliters
of water per 1000 ml of formula or milliliters of water per liter of formula)
- 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
Caloric density (kcal/ml formula)
Water content (ml/1000 ml formula)
1.0 – 1.2
- Vitamin and minerals
- Most nutritionally complete commercial formulas contain
adequate vitamin and minerals when a sufficient volume of formula to meet
energy and macronutrient needs is provided.
- Some disease specific formulas are nutritionally incomplete
in relation to vitamin and mineral content
- Liquid vitamins and mineral supplements may be indicated
for patients receiving nutritionally incomplete or diluted formulas for
- 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
- Definition: function of size and quantity of ionic and
molecular particles (protein, carbohydrate, electrolytes, and minerals )
within a given volume
- Unit of measure for osmolality is mOsm/kg of water Vs
unit of measure of osmolality mOsm/L.
- Factors affecting osmolality are:
- Minerals/electrolytes: due to dissociation properties and
- Protein: more hydrolyzed components such as amino acids
have greater osmotic effect than larger molecular weight component such
as intact protein.
- Carbohydrate: more hydrolyzed components such as glucose
have a greater osmotic effect than larger molecular weight such as starch;
- Formulas with greater hydrolyzed nutrient components have
proportionately higher osmolalities.
- Effect of osmolality on GI tolerance: gastric retention,
abdominal distention, diarrhea, nausea, and vomiting.
- Gastric motility is reportedly slowed with solution lower
than pH 3.5.
- The pH level of most commercial formulas is > 3.5.
- Calorie and nutrient density : gastric emptying time
may be slowed by formulas containing higher calorie-nutrient density
Classification of formulas
- Polymeric formulas:
- Most of patients who are critically ill may be enterally
fed with polymeric formulas.
- 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.
- 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.
- Partially hydrolyzed formulas:
- Macro-nutrients may be partially or completely hydrolyzed
via enzymatic activity into smaller components (e.g., free amino acids and
- Some formulas may have unpleasant odors and taste,
- Most of the formulas are expensive.
- Composition may vary in free amino acids and peptides, type
and quantity of fat, content of carbohydrate content.
- 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.
- 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
- Modular formulas:
- One purpose for using modular formulas is supplemental use
- May add calorie or protein density
- Tailor tube feeding to individual nutritional needs as a
supplement to commercial enteral formulas.
- Another advantage is that it can be de novo formulated for
individualized designed of nutrient formula to meet specific nutrient needs
of an individual.
- Advantages of de novo enteral formulation include
- Customizing the formula to meet specific nutrient composition
of the patient
- Select cases using de novo formulas have reported
- Disadvantages of de novo formula include
- Complexity of ordering specific nutrient composition as
well as the method and rate of tube feeding administration unless a standardized
orders form is used.
- Increased cost of labor
- Complexity of calculating nutrient composition
- Potential risk of bacterial contamination from excessive
handling of formulas
- Potential physical incompatibilities with insoluble components.
Determining an optimal access route for enteral nutrition
- Anticipated duration of enteral feeding
- 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
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.
- Determine the calorie content of the formula by multiplying
the total volume (cc) calorie/cc of the formula.
Example 1800 cc X 1.06 kcal/cc = 1908
- 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.
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
- Determine the actual calories and protein provided
by multiplying the calories and protein per liter by the strength of
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
100 cc / kg for the first 10 kg
50 cc / kg for the next 10 kg over 10
20 cc / kg for the number of kg over
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
(Final fluid requirement will be
depend upon disease condition)
Initiation of feeding
- Prior to initiating enteral feeds, tube placement must
- Placement can be confirmed by the aspiration of gastric
- 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.
- If gastric content can not be aspirated through the tube,
then radiographic confirmation of tube location should be done.
- 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.
- If intolerance develops at any time appropriate adjustment
should be made.
- 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.
- Strength and rate should not be advanced concurrently.
Determining the method for the tube feeding
- The method selected depend upon
- Central access route
- Stability of the patient (whether patient is critically
ill or not.)
- Gastric emptying rate
- GI tolerance of tube feeding
- Type of formula use
- Calorie and protein needs
- Ease of administration
- Patients mobility.
- The Feeds are given either by continuous drip, intermittent
infusions, and bolus feed.
- 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.
- 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.
- 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:
- Solution can be administered chilled if they are infused
by continuous drip
- Decreased incidence of GI side effects may occur if intermittent
and bolus feedings are allowed to reach room temperature prior to administration.
- Use close feeding containers to decrease risk of organism
- Extension tubing administration set and bag should be changed
- Never add new formula to old formula.
- Prepared formulas should be refrigerated if not used immediately.
- Feeding solutions should not be allowed to hang for longer
than 8 to 12 hrs.
Prevention of aspiration:
- Placement of tube should be checked prior to feeds.
- Head of bed should be elevated at least 30 to45 degrees.
- Few drops of food color may be added to enteral formulas.
This will help in detection of aspirated of tube feeding from pulmonary
secretions but does not protect against aspiration.
- The technique of aspirating gastric residuals via the feeding
tube is common practice although not based on scientific studies. Tube position
or mechanical difficulty may give inaccurate assessment. In general the
practice is limited to larger bore feeding tubes. The smaller tubes collapse
when aspiration is attempted. Generally feeds are held if aspirate is between
75 to 150 cc.
- Feeding tube should be irrigated every shift washed with
40 to 50 cc of warm water after its use.
- Even after each feed stopped, tube should be flushed with
40 – 50 cc of warm water.
- In case of clogging flush the tube, using a syringe containing
30 to 50 cc of warm water.
- Medicine should be liquid if it has to pass through tube.
The tube should be flushed with 20cc water before and after administration
- Complications associated with enteral tube feeding may be
prevented and managed with appropriate monitoring.
- Monitoring schedules are diversified because of patients
stability, institutional protocol, and feeding duration.
- Tube position confirmation prior to initiation of feeding
or prior to intermittent feeding
- Daily weight
- Daily intake and output of urine fractionals every six
hours until maximal tube feeding rate is established.
- Patients with history of diabetes mellitus should have
urine fractionals daily until therapy terminated.
- Record of gastric residuals every four hours when feeding
- Record of bowel movements/consistency
- Weekly serum electrolytes and blood count
- Weekly profile of liver function tests, phosphorus, calcium,
and magnesium, total protein albumin, nitrogen balance.
- Weekly reassessment of nutritional indices with appropriate
readjustment in energy and protein provisions needed.
- Prevention of mechanical, GI, and infectious complications
of tube feeding
- Total quality care of tube feeding patients requires interdisciplinary
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
Family can take an active part in food preparation for
Commercially prepared products can be 10% to 50% more
Cost of commercial products is not always reimbursable.
Payment is depend upon necessity of use as dictated by
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.
- Measure all ingredients accurately. Pour into large mixing
bowl and stir contents to combine.
- Blender method; add three cups of mixture to blender. Set
at medium speed for three minutes. Pour into separate large bowl. Repeat
above procedure until formulas have been thoroughly mixed.
- Mixer method: using an electric mixer, blend at medium
speed five minutes or until thoroughly mixed
- If mixture is thick, thin with water until the desire consistency
- Pour formula into individual jars. Cover and refrigerate
immediately. Discard any unused formula within 24 hours
- Take individual serving out one hour before needed and allow
it to warm to room temperature before use. Always keep it covered.
- The patient/caretaker should follow the direction given to
him regarding feeding