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Pediatric
Tube Feeding
Enteral
Feeding
Enteral tube feeding is the delivery of liquid nutrients
through a tube directly into the gastrointestinal tract.
In pediatric cases, it is used for children and infants
with a functioning gastrointestinal (GI) tract who are
not able to orally ingest adequate nutrients.
Conditions indicating tube feeding can include:
- Gastrointestinal
disorders of absorption, digestion, uptake and utilization,
secretion, or storage of nutrients, including congenital
anatomical or metabolic disorders, severe allergies,
severe gastroesophageal reflux, and food refusal behavior.
- Neuromuscular
disorders, such as cerebral palsy, muscular dystrophy,
spinal cord defects, or damage to the central nervous
system.
- Cardiopulmonary
disorders and conditions of hypermetabolism (e.g.,
burns, some forms of cancer).
- Prematurity
and/or failure to thrive.
It is important to distinguish between enteral and parenteral
feeding:
-
Enteral feeding delivers digestible
nutritive formula through a tube into an intact, functioning
gastrointestinal system, bypassing problems with normal
oral ingestion.
- Parenteral
feeding, also called total parenteral nutrition (TPN),
delivers a more elemental formula intravenously, directly
into the circulatory system, when the gastrointestinal
system is malfunctioning or otherwise compromised,
bypassing both ingestion and digestion.
The types of enteral tube feeding are classified according
to the point from which the tube enters the body and
the point to which the nutrient formula is delivered:
- Nasogastric
(NG) from the nose to the stomach.
- Nasoduodenal
from the nose to duodenum (the first or upper part
of the small intestine, immediately below the stomach).
- Nasojejunal
from the nose to jejunum (the next or middle part
of the small intestine, and before the much longer
ileum).
- Gastrostomy
(GT) from a surgical opening in the skin, through
the abdominal wall, and directly into the stomach.
- Jejunostomy
(JT) from a surgical opening in the skin, through
the abdominal wall, and directly into the jejunum.
Digestive
System Diagram
A physician’s choice of which type of tube feeding
to use depends on anatomical, digestive, and feeding
behavior factors, as well as expected duration of the
tube feeding. Nasogastric and gastric tube feeding are
the most commonly used.
Nasogastric
Tube Feeding (NG tube)
Nasogastric intubation is a medical process not requiring
surgery by which a flexible tube is passed through the
nose, down through the throat and esophagus, and into
the stomach. Its main purpose is for feeding and for
administration of drugs or other medically indicated
oral agents.
Nasogastric intubation is not advisable for patients
with facial trauma, skull fracture, esophageal abnormalities
or certain deformities, problematic mental state, or
an impaired airway.
Typically minor complications can include sore throat,
sinusitis, or nose bleeds. Rarely, more significant
complications may require immediate medical attention
and consideration of surgical alternatives to nasal
insertion.
Sometimes the goal of short-term enteral feeding in
patients with gastroparesis or other contraindications
must be to deliver the enteral solution beyond the pylorus
of the stomach. Endoscopic methods allow the precise
location of the tube in the small intestine, either
the duodenum or the jejunum. Complications can be feeding
tube migration back into the stomach during the withdrawal
of the endoscope or by inadvertent shifting during feeding,
but it is correctable. Unlike nasogastric intubation,
these procedures are not suitable for a trained parent
or caregiver.
Gastric
Tube Feeding (G Tube)
The most common surgical procedure for insertion of
a feeding tube into the stomach is percutaneous endoscopic
gastrostomy (PEG). An endoscope is directed through
the mouth and esophagus into the stomach of the sedated
patient. The endoscope provides a powerful light source
to reveal its position in the stomach as viewed from
outside the body. A soft guide wire or suture is inserted
through a small incision, grasped by the endoscope,
and pulled up through the esophagus. The PEG tube can
then be pulled back down into the stomach and out through
the incision, with the delivery end of the tube retained
in the stomach by a balloon tip or retention dome. The
surgery is simple, involves little risk or discomfort,
and takes about 20 minutes. Feeding tubes placed in
this manner are not painful and when not in use can
be taped to the skin to prevent moving around under
clothing.
Gastric tubes are favored for long-term use, last up
to six months and can be replaced without additional
surgery.
In patients for whom the stomach as the point of delivery
is problematic, the jejunum or duodenum are alternate
targets for percutaneous placement of feeding tubes,
similar to PEG but by jejunostomy or duodenostomy.
As with all types of feeding tubes, the physician’s
choice or PEG must consider all patient-specific factors.
Contraindications include existing peritonitis or abdominal
wall infection, high risk of aspiration, or unusual
GI anatomy (such as malrotation).
Complications that may result from percutaneous insertion
include cellulitis (infection around the incision point),
peritonitis (infection within the abdominal cavity),
gastric separation, and tube migration within the GI
tract or back into the abdominal cavity.
Tube
Feeding Administration
Tube feedings of infants and children can be administered
by continuous gravity drip, regulated infusion pump,
periodic bolus, or some combination. When oral feeding
is also possible, the best combination is a regular
schedule of normal and tube feeding that fits the needs
and routines of the child and the family.
For periodic bolus feeding, the enteral formula is delivered
at regular times each day, with each feeding lasting
up to half an hour. Bolus refers to the discrete volume
of nutrient material moving through the GI tract. Advantages
of bolus feeding include reduced expense, convenience,
freedom of movement between feedings, and similarity
to a normal eating schedule. Disadvantages can include
an increased possibility of aspiration compared to continuous
drip feeding, and in some cases diarrhea, bloating,
and cramping when the necessary volume is too large.
For continuous drip feeding, a direct gravity system
is normally used, with the container of enteral formula
placed higher than the patient’s stomach. While
enteral formula may be delivered 24 hours a day, this
is not advisable as it limits the child’s freedom
of movement and may contribute to hypoglycemia. Typically,
continuous drip is administered for several hours during
the night so that smaller regular bolus or oral feedings
can be administered during the day. Gravity drip may
be inconsistent in delivery rate and must be frequently
monitored.
For regulated infusion pump feeding, an electronic pump
is used to control and measure the intake without any
interruption, and as with gravity drip, may be administered
during the night to reduce interference with normal
daytime activities. It is the most expensive option.
Enteral
Formula
The choice of an enteral formula is specific to the
patient, and a range of prepared formulas are available
commercially. Home formula preparation is also an option.
The selection of an enteral formula should be with by
the direction and guidance of a doctor or nutritionist.
The condition and capacity of the GI tract, any underlying
disease, allergies or food intolerance, and age must
be considered in determining an appropriate formula.
Likewise, the type of tube and its placement are considered
for effects of viscosity, tonicity, and amount and frequency
of administration.
Osmolality
and Tonicity
Osmolality is a measure of the concentration of chemical
compounds (amino acids, carbohydrates, electrolytes)
present (by weight) that affect the osmotic behavior
of the formula. Tonicity is a measure of the osmotic
behavior relative to the normal body fluids. A formula
with a higher effective osmolality (hypertonicity) than
normal body fluids will draw water into the GI tract
to dilute the concentration. Too much water in the GI
tract can cause nausea, cramping, distention, and diarrhea.
If the effective osmolality is too low (hypotonicity),
affected cells will swell or even burst causing serious
inflammation and other complications. The preferred
condition is isotonicity, in which the enteral formula
and the cells of the GI tract are in osmotic equilibrium
until acted on by normal digestive processes.
Types
of enteral formulas include:
- Standard
formulas are nutritionally complete, intended for
patients with normal GI-tract who cannot ingest adequate
nutrients and calories. They are usually isotonic,
convenient and sterile.
- Home-prepared
formulas are more time-consuming but less expensive
than commercial standard formulas. Infant formula
or milk is often used as a base for blenderizing a
complete dietary formula as directed by a doctor or
nutritionist. These formulas are more effectively
delivered through a gastric tube (G tube), since they
can tend to be too viscous to pass through the narrower
nasogastric tube (NG tube) without clogging.
-
Elemental formulas contain predigested
nutrients and essential vitamins and minerals. Their
advantage is that little digestion is required and
excretion of stool is minimal. Their disadvantage
is high molality, and if infused too rapidly can cause
osmotic diarrhea. They are also more expensive.
- Modular
formulas contain specific nutrients, to be added to
commercial or home-prepared formulas to meet special
nutritional needs.
- Specialized
formulas are designed for special cases identified
by a doctor or nutritionist, usually involving prematurity
or congenital errors of metabolism.
The
nutrient composition of complete enteral formulas will
include:
- Carbohydrate
sources must be water soluble and easily digestible
or absorbed in the GI tract. Common carbohydrate sources
include corn syrup solids, hydrolyzed cornstarch,
maltodextrin (starch-derived polysaccharide), and
other forms of glucose (monosaccharide or simple sugar).
- Lipids
are a high calorie energy source. Corn or soybean
oil are commonly used. Fat content provided by lipids
is adjusted as, for example, glucose intolerance calls
for higher fat content while intestinal malabsorption
calls for lower fat content.
- Proteins
may delivered intact or partially predigested, or
as free amino acids. Common sources are caseinates
(a form of dairy protein) or soy protein. Polymeric
formulas use intact proteins. Oligomeric formulas
contain enzymatically hydrolyzed (predigested) proteins.
Monomeric formulas contain free amino acids.
- Water,
as the enteral formula solute and essential for hydration,
determines the caloric density of the formula. Lower
caloric density is about 85% water; higher caloric
density is about 70% water.
- Micronutrients,
in adequate volume, insure complete nutrition as 100%
of RDA (recommended daily allowance) for vitamins
and minerals. The volume required varies greatly among
products and among patients by age and weight. Some
disease-specific formulas are not nutritionally complete.
- Fiber,
usually insoluble soy polysaccharide, is added to
control stool consistency. Sources of soluble fibers
including oat fiber, guar gum, and pectin are also
used. Fiber can be a complication for patients on
restricted fluids or with delayed GI motility.
Some widely available commercially prepared pediatric
enteral formulas include: Compleat Pediatric, Neosure,
Nutren Junior, Pediasure, Peptamen Junior, Pediatric
Peptinex, Resource Just for Kids, among others. Most
of these brand labels provide a range of formula options,
including additional fiber.
Links
to key .org and .gov sites
Gaining and Growing: Enteral Feeding for Children
depts.washington.edu/growing/Nourish/Tubekids.htm
National Center for Biotechnology Information
(NCBI)
ncbi.nlm.nih.gov/
NCBI Nasogastric Intubation Videos
ncbi.nlm.nih.gov/pubmed/16641390
North American Society for Pediatric Gastroenterology,
Hepatology, and Nutrition (NASPGHAN)
naspghan.org/
Pediatric Nutrition Practice Group (PCPG)
pediatricnutrition.org/pdfs/PNPGReferenceList.pdf
Selected
Citations
“Enteral Formula Selection: A Review of Selected
Product Categories” Practical Gastroenterology:
Nutrition Issues in Gastroenterology, Series #28, June
2005
“Pediatric Enteral Nutrition” JPEN: Journal
of Parenteral and Enteral Nutrition, Jan/Feb 2006, Axelrod
et. al.
Baker, Baker, and Davis (1994). Pediatric Enteral Nutrition.
Jones & Bartlett Publishers.
Multiple sources for “pediatric tube feeding”
and “pediatric enteral feeding” at pubmed.gov
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