TOTAL PARENTERAL NUTRITION MANAGEMENT
Category: Child Health
Abstract : TOTAL PARENTERAL NUTRITION MANAGEMENT Goals for nutrition management The
primary goal is to provide energy and nutrients in sufficient quantities to
allow normal growth and development. Although the goal is to have growth rates
that follow either the intrauterine growth curve for premature infants or the
postnatal growth curve for term infants, this is rarely achieved during the
ac
TOTAL PARENTERAL NUTRITION MANAGEMENT
Goals for nutrition management
The
primary goal is to provide energy and nutrients in sufficient quantities to
allow normal growth and development. Although the goal is to have growth rates
that follow either the intrauterine growth curve for premature infants or the
postnatal growth curve for term infants, this is rarely achieved during the
acute phase of an infant's illness.
Calculations
When calculating FEN
requirements, most practitioners use an infant's birth weight until the infant
has regained the birth weight. Thereafter, daily weight is used in calculations.
Total parenteral nutrition (TPN) can be started on the first or second day of
life in infants who are not likely to achieve total enteral nutrition within the
first week of life. Especially in infants who are ill, protein is required to
decrease or prevent catabolism, and starting TPN on the first day is
important.
The goal for TPN is to provide 90-100 kcal/kg/d with 2.5-3
g/kg/d protein.
• Fluid requirement: Calculate the infant's daily fluid
(water) requirement. Then, determine the delivery method, either parenteral (IV)
or enteral (OG/PO).
• Energy requirement: Calculate the amount of energy
required.
o Determine the specific amounts and sources of carbohydrates and
lipids.
o Determine the amount of protein to deliver based on the total
number of calories to be provided. Keep in mind that an infant needs an adequate
number of nonprotein calories (150-200 kcal/g nitrogen) to have a positive
balance of nitrogen. Most practitioners start at 1.5 g/kg/d of protein on the
first or second day and increase daily by 0.5-1.0 g/kg/d, as tolerated. Various
amino acid preparations are commercially available for use in the neonate (eg,
TrophAmine).
• Determine the amounts of vitamins and trace elements to
deliver.
Carbohydrate
IV dextrose provides most of the energy in TPN.
The caloric content of aqueous dextrose is 3.4 kcal/g glucose, which is equal to
34 kcal/100 mL of D10W. As a result of the high osmolarity of concentrated
dextrose solutions, the maximum dextrose concentration that can be delivered
safely through a peripheral vein is 12.5%. Even with central venous access, a
dextrose concentration exceeding 25% usually is not required.
A glucose
infusion rate expressed in mg glucose/kg/min is the most appropriate way to
express glucose administration, since the rate accounts for both the glucose
concentration and rate of infusion. Very small premature infants weighing less
than 1500 g demonstrate impaired glucose tolerance. For this reason, in infants
weighing less than 1 kg, start at an infusion rate of 6 mg/kg/min. In infants
weighing 1-1.5 kg, start at 8 mg/kg/min. If the glucose infusion rate is
excessive, hyperglycemia develops. If blood glucose levels are greater than
150-180 mg/dL, glucosuria occurs, producing an osmotic diuresis and dehydration.
This can be controlled either by decreasing the glucose infusion rate or by
treating the infant with insulin.
Fat
At least 3% of the total energy
should be supplied as essential fatty acids (EFA). This can be accomplished by
providing Intralipid 0.5 g/kg/d 3 times per week. Parenteral fat usually is
provided as a 20% lipid emulsion made from soybeans (eg, Intralipid). Intralipid
is a concentrated source of energy with a caloric density of 2 kcal/mL (for 20%
Intralipid). Most practitioners start with 0.5-1.5 g/kg/d on the first day and
increase steadily to 3-3.5 g/kg/d. Limiting Intralipid infusions in infants with
sepsis and severe lung disease is generally recommended.
Neonates with
hyperbilirubinemia who are on phototherapy often have Intralipid intake
restricted to less than 2 g/kg/d (especially if bilirubin levels are rising
while on phototherapy) because some evidence exists that high lipid-emulsion
intake may decrease bilirubin binding (Spear, 1985). Many practitioners monitor
triglyceride levels and adjust infusion rates to maintain triglyceride levels of
less than 150 mg/dL.
Protein
Term infants need 1.8-2.2 g/kg/d along
with adequate nonprotein energy for growth. Preterm VLBW infants need 3-3.5
g/kg/d along with adequate nonprotein energy for growth. Usually, providing more
than 4 g/kg/d of protein is not advisable. Infants under stress or who have
cholestasis usually are limited to 2.5 g/kg/d of protein because it has been
observed that the severity of TPN-induced cholestasis may depend on the duration
of TPN and the amount of amino acids infused (Sankaran, 1985; Yip,
1990).
Protein supplementation should be started early, as soon as FE
requirements have stabilized. Very high protein intake, at greater than 5-6
g/kg/d, may be dangerous. Maintain a nonprotein-to-protein calorie ratio of at
least 25-30:1. The current role of supplements, such as additional glutamine,
inositol, and carnitine, is under investigation. Although a physiologic
rationale exists for their use, they have not yet been shown to be of benefit in
large randomized controlled trials; however, to date, small clinical trials are
promising.
Minerals (other than sodium, potassium, chloride)
• Calcium
and phosphorus (Ca and P): Once protein intake has been started, calcium and
phosphorous should be added to the TPN. Take care to ensure that solubility is
not exceeded. If this happens, calcium and phosphorous may precipitate
spontaneously.
• Magnesium (Mg): Supplemental Mg should be added to TPN
once protein has been added. Vitamins and trace elements
• Vitamins A, D,
E, and K are fat soluble.
• Vitamins B-1, B-2, B-6, B-12, C, biotin,
niacin, pantothenate, and folic acid are water soluble.
• Vitamin
supplementation should be started as soon as protein is added to the TPN. The
addition of a commercially available neonatal vitamin preparation provides
appropriate quantities of all vitamins, except possibly vitamin A. Evidence
exists that therapeutic doses of vitamin A (5000 IU administered IM 3 times/wk)
may reduce the incidence of chronic lung disease and other long-term adverse
outcomes in ELBW infants.
• The trace elements zinc, copper, selenium,
chromium, manganese, molybdenum, and iodine also should be added to TPN once
protein is started. This can be easily accomplished by the addition of a
commercially available solution containing trace elements.
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