Nutrition Support: Enteral Nutrition

Feeding through the GI tract via a tube, catheter, or stoma (opening) that delivers
nutrients distally (below) the oral cavity
Indications

Patients with a functioning GI tract that
Contraindications

Patient has serious medical
can’t feed themselves adequately such
conditions that affect the GI tract
as those with
such as
o Altered mental status
o Diffuse peritonitis –
o Swallowing dysfunction
inflammation of the
o Disorders of the upper GI
peritoneal lining of the
tract – can be bypassed by
inserting the tip of the
abdominal cavity
o Intestinal obstruction that
feeding tube below the area
prevents intestinal contents
of dysfunction
from passing through the
intestine
o Intractable vomiting not
responsive to medical
treatment
o Paralytic ileus – prevents
GI contents from passing
through the GI tract
o Intractable diarrhea that is
not controlled by
medications
o Gastrointestinal ischemia –
insufficient blood flow to GI
tissues
Advantages
 Cost effective
 Reduced rate of infections in
critically ill patients
 Improved wound healing
 Reduced surgical intervention
 Maintenance of GI tract functions
Disadvantages
 Difficult to administer
 Poor tolerance
 Difficulty of meeting nutritional
requirements of some patients
 Discomfort of the patient
GI Access
1. Nasogastric Feeding tube  A tube that is inserted through the nose into the
stomach
o Most common
o Easiest to achieve
o Easiest to maintain
o Least expensive
o Can be used in various conditions
Disadvantages:
o Can be easily dislodged
o May need to be replaced frequently
2. Orogastric Feeding tube
o Tube that is inserted through the mouth to the stomach
3. Nasointestinal Feeding tube
o Tube that is inserted through the nose into the intestine bypassing the
stomach to reside in the duodenum or jejunum used in cases of

Gastroparesis – delayed gastric emptying

Gastric outlet obstruction

Previous gastric surgery preventing feeding into the stomach
o Minimizes risk of accidental aspiration of formula into lungs
Tubes entering through the nose or mouth are used for short term therapy (<6 weeks)
More permanent feeding tube methods
4. Gastrostomy
o Tube delivering feeds to the stomach
5. Jejunostomy
o Tube delivering feeds through the abdominal wall into the jejunum
Both methods involve placement of the tube by the following procedures:
Surgical Gastrostomy
o Physician places permanent feeding tubes when the patient is sedated
Percutaneous Gastrostomy
o Feeding tubes placed through the skin without a surgical incision
Percutaneous Endoscopic Gastrostomy (PEG)
o Inserting a feeding tube through the skin into the stomach using an
endoscope
Formulas
Depends on where the tip of the tube is and on osmolality – number of water attracting
particles per kg.
1. Protein

Derived from soy or casein

Most formulas require enzymes to split intact proteins into peptides before
absorption – standard formulas

Some contain proteins from peptides used in patients with enzyme deficiency or
other conditions resulting in maldigestion – elemental or hydrolyzed formulas

Specialized amino acid formulas – elemental formulas - are used for
o Renal failure
o Hepatic failure
o Stress
o Inborn errors of metabolism
2. CHO

Large molecules (monosaccharides, oligosaccharides, dextrin, maltodextrins)

Most have insoluble fibres (i.e. soy polysaccharides)
o Less hydrophilic

Some have soluble fibre added to improve bowel functions
o Only small amounts as these formulas are hydrophilic – attracts water

Causes formula to thicken and form a gel when added
3. Lipids

Derived from corn and soy oil – long and medium chain fatty acids
4. Vitamins/Minerals

Most provide DRIs for vitamins and minerals for adults within a specified volume (i.e.
1500 mL in 24 hours)
5. Fluid/Nutrient Density

Some patients are unable to tolerate large volumes of fluid as they have impaired
functions
o Cardiac
o Renal
o Pulmonary

Nutrient density determined by kcal/mL
o Standard is 1 kcal/mL

EN may be the sole source of fluid intake – monitor patient’s ins and outs to check
for dehydration

Precise water content of formulas are determined by the free water content
o 80% water for 1 kcal/mL
o 65 % water for 2 kcal/mL

Partially hydrolyzed formulas have higher Osmolality
o Number of water attracting particles per weight of water in kgs (mOsm/kg)

Iso-osmolar – formulas that have the same osmolality of body fluids (300 mOsm/kg)
o Was used to minimize the effects of dumping syndrome – diarrhea resulting
from rapid movement of fluids into the GI tract to dilute hyperosmolar or
concentrated fluids

Typically most formulas have moderate osmolality (300 – 600 mOsm/kg)
Feeding Techniques
1. Bolus Feeds

Rapid administration of 250 – 500 mL of formula several times daily using a syringe
2. Intermittent Feeds

Administered several times daily over 20 – 30 minutes

Typically requires a pump to control flow rate or can use gravity feeds if container is
suspended above the patient
3. Continuous Feeds

Administered over 10 – 24 hours daily using a pump to control feeding rate preferred method in hospitals or nursing homes
o May improve tolerance

Can be restrictive on mobility
Most polymeric, isotonic formulas can be initiated at 10 – 40mL/ hour
-
Rate is advanced in increments of 10 – 25mL/ hour every 4 - 8 hours until goal rate
is reached
Complications
Mechanical

Clogged, twisted or kinked tubes – flush with water
Gastrointestinal

most common is diarrhea
o abnormal looseness of stool with increased liquidity or decreased consistency
o output > 200 g/day for adults and 20 kg/day for children

can be caused by medications – antibiotics containing sorbitol

also due to infections by bacteria or viruses
Aspiration

fluid is inspired into the lungs

common in patients who are
o sedated
o have endotracheal tubes – tube allowing oxygen into the lungs of patients
receiving mechanical ventilation
o have swallowing difficulties
-
elevate patient’s head about 45 during feeding
-
determine GI emptying by calculating residual volumes of liquid in stomach
o stop EN if residual > 400 mL
Tube Feeding Syndrome

hyperosmolar-nonketotic dehydration over a short 2 to 4 day period caused by
insufficient fluid intake in patients with EN
Electrolyte Imbalances

patients with organ failure require lower levels of electrolytes

IV supplementation of electrolytes are preferred
Underfeeding

Delays nutritional repletion and wound healing

May assist in preventing acute and respiratory complications in some patients
Overfeeding

Ureagenesis
o Inability to clear by-products of protein breakdown resulting in toxicity

Hyperglycemia
o Impaired wound healing

Hypertriglyceridemia

Hepatic Steatosis – fatty liver
o Due to an increase of liver enzymes that promotes increased storage of fatty
acids
o Congestion of the reticular endothelial system – increased serum tryglycerides

Prolonged mechanical ventilation
o Increased CO2 production due to increased metabolism of CHO
Refeeding Syndrome

Metabolic alterations that occur during the nutritional repletion of starved patients
o In starved patients, major energy source is from fatty acids used to produce
ketones resulting in decreased BMR

Reintroduction of CHO results in shift of energy source from ketones to glucose

Glucose requires large quantities of phosphorus to be metabolized
o Magnesium, potassium and thiamin needs may increase as well

Serum phosphate decreases (hypophosphatemia) resulting in
o Hemolysis
o Impaired cardiac function
o Impaired respiratory function
o Death

Serum potassium decreases (hypokalemia) resulting in
o Cardiac abnormalities

Serum magnesium decreases (hypomagnesemia) results in
o Tremors
o Twitching muscles
o Cardiac arrythmias
o Paralysis
Patients at highest risk are:

Malnourished

Have a history of long-term inadequate oral intake

Have had minimal intake for several day
Parenteral Nutrition

Administration of nutrition directly into the circulatory system via IV – intravenously
Central Parenteral Nutrition

Administration of concentrated macronutrients, vitamins, minerals and electrolytes
into a large central vein so that the volume of blood flow is sufficient to immediately
dilute the concentrated PN solution
Peripheral Parenteral Nutrition

Administration of large volumes of dilute solutions of nutrients into a vein in the arm
or the back of the hand

Usually used for short-term
Indications:

Patient unable to meet needs by EN or oral intake

Inability to digest and absorb nutrients – malabsorption
o Massive bowel resection
o Short bowel syndrome
o Intractable vomiting
o GI tract obstruction
o Impaired GI motility
o Abdominal trauma, injury or infection
Venous Access
Short Term:
1. Central Venous Catheter
o IV access inserted into large veins at the centre of the body such as the

Subclavian

Jugular

Femoral veins
2. Peripherally inserted central catheter (PICC)
o IV access inserted into the arm and threaded into a subclavian vein to the
vena cava
o Threaded from smaller veins to larger veins
o Inserted bedside – doesn’t need surgical placement
Long Term
1. Tunneled Catheters
o IV access placed in a vein on the upper chest wall and exits the body near the
xyphoid process, axilla or abdominal wall
o Surgically inserted directly into the superior vena cava
o Better suited for long-term support

Patient can use both hands to access it

Less chance of displacement as it is sutured in place
2. Implantable Ports
o IV access that is completely under the skin
o Placed in the vein on the upper chest wall and exits the body near the xyphoid
process, axilla or abdominal wall