http://www.fda.gov/Drugs/DevelopmentApprovalProcess/DevelopmentResources/ucm049867.htm.
Fluid requirements and calories normalized to body weight are much
greater in very small children than in older children and adults. It is
important to understand how to calculate the normal fluid and caloric
needs of children, and how fluid and caloric needs change with changes
Human milk is the ideal food for a human infant. In addition to meeting
the infant’s nutritional requirements, human milk provides the infant with
protection against a wide variety of infectious diseases and
noninfectious disorders. Solid foods are generally introduced at 4 to 6
months of age, and pure cow’s milk is generally introduced after 1 year.
Infant formula is available in three different formulations: cow’s milk
hydrolysate formulas are primarily intended for infants who are
intolerant of cow’s milk-based formulas. Other therapeutic formulas are
available or can be made for infants with disease states that preclude
the use of one of these three main types of formula.
Growth assessment is an important focus of pediatric health care,
especially during the first year of life. With the exception of the
intrauterine period, the most rapid growth occurs during the first year.
Parenteral nutrition in infants and children is usually initiated below
estimated caloric needs and advanced as tolerated over the course of 3
or more days until goal caloric needs are met.
Parenteral nutrition can be used to supply sufficient nutrients to promote
healing and a normal rate of growth in sick infants and children.
However, parenteral nutrition is associated with clinically significant
Specialized pediatric amino acid solutions are available for infants
younger than 1 year of age. These products were designed to produce
plasma amino acid patterns closely matching those of human milk-fed
Irreversible liver damage can occur with long-term parenteral nutrition.
Parenteral nutrition-associated liver disease usually presents as an
elevated direct (conjugated) hyperbilirubinemia and can occur as early
as 2 weeks after beginning parenteral nutrition.
A number of modifications can be made to the patient’s parenteral
nutrition regimen to alleviate or slow the progression of cholestasis. The
initiation of enteral feeding, even if limited to low-volume trophic
feeding, appears to be the most effective method for preventing
Adequate nutrition is an essential component of the health maintenance of children
and, in part, has been responsible for the dramatic reduction of infant mortality seen
in the United States during the 20th century. Clinical experience has confirmed the
value of optimal nutrition in resisting the effects of disease and trauma and in
improving the response to medical and surgical therapy. The metabolic demands of
rapid growth and maturation, in addition to the low nutritional reserves present
during infancy, make the potential benefit of good nutrition to critically ill pediatric
Breast-feeding is the ideal method of feeding an infant and should be continued for
at least the first year of life whenever possible. When this is not feasible, various
infant formulas are available that provide appropriate nutrients for infants using the
oral route. A pediatric patient who has a functioning intestinal tract, but is unable to
achieve adequate oral intake, can be fed enterally using a tube inserted into the
stomach or small intestine. Indications for providing specialized enteral nutrition
include malnutrition, malabsorption, hypermetabolism, failure to thrive, prematurity,
and disorders of absorption, digestion, excretion, or utilization of nutrients.
Despite the many formulas and feeding techniques available, several medical and
gastrointestinal (GI) dilemmas that limit the use of the GI tract for nutritional support
can occur in infants and children. Premature infants with severe respiratory disease,
congenital abnormalities of the GI tract, or necrotizing enterocolitis are typical
candidates for support with parenteral nutrition (PN). Older children with short
bowel syndrome, severe malnutrition, intractable diarrhea, or inflammatory bowel
disease have been treated successfully with PN therapy. Pediatric patients receiving
chemotherapy for the treatment of malignancies or bone marrow transplant and
children with severe cardiac failure also have been successfully rehabilitated with
Many disorders that adversely affect nutrient intake or absorption also have an
adverse impact on fluid and electrolyte status. Consequently, fluid, electrolyte, and
nutrient management should be approached in an integrated manner. This chapter
reviews selected aspects of fluid and electrolyte management and nutrition therapy
FLUID AND ELECTROLYTE MAINTENANCE
Management of fluid and electrolyte disturbances involves providing normal daily
maintenance requirements and replacing deficits and ongoing losses. To design
rational fluid therapy, it is necessary to know the normal composition of body water
and to understand the routes through which water and solutes are lost from the body
NaCl). Normal saline contains 154 mEq/L of sodium chloride.
Calculation of Maintenance Fluid and Electrolyte
electrolytes include the following:
General recommendations for calculating maintenance fluid have not changed
significantly since first outlined by Holliday and Segar in 1957.
electrolyte and nutrient replacement is still based on guidelines published in 1988 by
2 Fluid, electrolyte, and nutrient requirements on the basis of weight are
provided in Table 103-1. Although a commercially available intravenous (IV)
solution will be used, each component of the solution can be calculated separately.
Using the guidelines in Table 103-1, P.J.’s maintenance requirements can be
Fluid and electrolyte requirements can be met by infusing a solution of 5%
dextrose with one-quarter NS (38 mEq/L) and 20 mEq/L of KCl at 15 mL/hour. This
provides 12 mEq (3.4 mEq/kg/day) of NaCl and 7 mEq (2 mEq/kg/day) of KCl in
360 mL (103 mL/kg/day) of fluid per day.
Additionally, fluid and electrolyte requirements can also be altered when fluid and
electrolyte losses are increase or when excretion is impaired. When abnormal fluid
losses are present, they must be given back to the patient daily. Replacement fluid is
generally 1 mL for every 1 mL lost, but can be more or less based on the patient’s
clinical status. In general, NS can be initially used for most replacement fluids.
The requirements for fluid and calories normalized to body weight are much
greater in very small children than in older children and adults as can be seen in
Table 103-1. This is because infants have a much larger body surface area relative to
weight, lose more fluid through evaporation, and dissipate more heat per kilogram
than their older counterparts. Furthermore, very low-birth-weight (VLBW) infants
cannot concentrate urine and are at increased risk for dehydration if inadequate fluids
today. Her vitalsigns are as follows:
Pulse, 140 beats/minute (normal, 80–130 beats/minute)
Respiratory rate, 30 breaths/minute (normal, 30–35 breaths/minute)
Blood pressure (BP), 80/45 mm Hg (normal, 80–115 mm Hg systolic and 50–80 mm Hg diastolic)
Daily Parenteral Nutrient Requirements in Children
Nutrient Weight/Age Requirement
10–20 kg 1,000 mL + 50 mL/kg for each kg >10 kg
>20 kg 1,500 mL + 20 mL/kg for each kg >20 kg
Calories Up to 10 kg 100 kcal/kg
20 kg 1,000 kcal + 50 kcal/kg for each kg >10 kg
>20 kg 1,500 kcal + 20 kcal/kg for each kg >20 kg
Adolescents and older 1.0–1.5 g/kg
b Infants and children Initially 0.5–1 g/kg and then increase by
0.5–1 g/kg (maximum of 3 g/kg in preterm
neonates, 4 g/kg older infants and children)
(≥4% of calories as linoleic acid)
>50 kg One 500-mL bottle (100 g fat)
Sodium Infants and children 2–4 mEq/kg
Potassium Infants and children 2–3 mEq/kg
Chloride Infants and children 2–4 mEq/kg
Magnesium Preterm and term infants 0.25–0.5 mEq/kg
Children >1 year (or >12 kg) 4–12 mEq
Calcium Preterm and term infants 2–3 mEq/kg
Children >1 year (or >12 kg) 10–20 mEq
Phosphorus Preterm and term infants 1.0–1.5 mmol/kg
Children >1 year (or >12 kg) 10–20 mmol
Zinc Preterm infants 400 mcg/kg
Children 50 mcg/kg (up to 5 mg)
Copper Infants and children 20 mcg/kg (up to 300 mcg)
Manganese Infants and children 1 mcg/kg (up to 50 mcg)
Chromium Infants and children 0.2 mcg/kg (up to 5 mcg)
Selenium Infants and children 2 mcg/kg (up to 80 mcg)
patients predisposed to sepsis and preterm infants) or 2 to 3 times weekly.
insufficiency may require none to low amounts of potassium, calcium, phosphorous, and magnesium.
Am J Clin Nutr. 1989;50(3):560]. Am J Clin Nutr. 1988;48(5):1324–1342.
H.S.’s lethargy, decreased urine output, tearless crying, dry mucous membranes,
dry skin with fever, sunken eyes, mild tachycardia with low normal blood pressure,
and poor skin turgor are all signs of dehydration. This is consistent with her 2-day
history of vomiting and poor intake. Her weight loss of 1.5 kg gives a further clue to
the extent of dehydration. Dehydration or fluid loss is determined most accurately by
weight loss. Because 1 g of body weight is approximately equal to 1 mL, her fluid
deficit is estimated to be 1,500 mL. The percentage dehydration is estimated using
Mild <5 Normal Slight Normal to
Moderate 6–10 Irritable Moderate Dry ± ± ± Increased
Intense Parched Absent Sunken Tenting Greatly
If recent weights are unavailable, the extent of dehydration can be approximated
from physical findings as described in Table 103-2. Tachycardia and marginal blood
pressure dictate the need for immediate IV rehydration. Normal serum sodium
concentration ranges from 135 to 145 mEq/L of sodium; thus, normal saline
approximates the sodium concentration of plasma and is often used as a volume
expander. In this patient, 10 to 20 mL/kg of normal saline (12.9 kg × 10–20 mL/kg =
129–258 mL) should be infused as rapidly as possible to establish normal blood
pressure. For symptomatic patients, including those with seizures, the serum sodium
concentration should be increased acutely only to the degree necessary to abate
CASE 103-2, QUESTION 2: Calculate H.S.’s fluid and electrolyte needs and provide recommendations for
her fluid orders to the team. Her serum electrolyte results were as follows:
Sodium, 128 mEq/L (normal, 135–145 mEq/L)
Potassium, 3.1 mEq/L (normal, 3.5–5 mEq/L)
Chloride, 88 mEq/L (normal, 102–109 mEq/L)
, 30 mEq/L (normal, 22–29 mEq/L)
In addition to normal maintenance fluids, H.S. must be provided with fluids and
electrolytes to replace her deficit secondary to dehydration and compensate for
increased insensible water loss because of fever. Each component of the fluid can be
calculated separately, using Equations 103-5 to 103-7.
where CD is the concentration of sodium desired (mEq/L), CO is the concentration
is the apparent distribution factor as a fraction of body weight
(Table 103-3), and weight is the baseline weight before illness (kg). In consideration
of both maintenance needs and current deficits, fluid and electrolyte requirements for
H.S. would be estimated as follows.
Electrolytes and Apparent Distribution
H.S. has a mild metabolic alkalosis as evidenced by her serum chloride of 88 mEq/L
and her serum bicarbonate of 30 mEq/L. This is most likely because of the loss of
hydrogen and chloride in her vomitus. Thus, both the sodium and potassium
replacements should be administered as chloride salts.
Potassium is primarily an intracellular ion. It moves in and out of cells in exchange
for hydrogen ions to maintain a normal blood pH. Therefore, in metabolic alkalosis,
the intracellular shift of potassium will decrease the serum potassium concentration.
When the pH normalizes, as will occur with rehydration, the hydrogen ions will
move intracellularly and the potassium will move extracellularly, thus causing the
serum potassium concentration to increase. Additionally, potassium is also excreted
by the kidney in exchange for hydrogen ion conservation. These factors make the
serum potassium concentration difficult to interpret. Intravascular volume depletion
causes hypoperfusion of the kidney and can result in acute renal failure; therefore, the
prudent approach is to give no potassium until urine output is clearly established.
Then, only maintenance doses of potassium should be administered until a normal
acid–base and fluid status are established and the serum potassium can be assessed
more accurately. Hence, H.S. should receive approximately 26 to 39 mEq of
potassium (2–3 mEq/kg × 12.9 kg) once urine flow is established.
Administration of Fluid Requirements
How should these calculated needs be given?
Requirements for the first 24 hours of parenteral fluid therapy should provide
approximately 2,875 mL of fluid to account for maintenance fluid needs, fever
replacement, and deficit replacement. In addition to fluid, at least 93 mEq of sodium
(maintenance needs plus deficit replacement) should be provided in the first 24
hours. It is important to provide sufficient amounts of sodium and water.
Rehydration fluids are usually dispensed in volumes less than the 24-hour
requirement. This is to prevent wasting IV fluids caused by changes in electrolyte
needs during replacement therapy. Because this patient requires approximately 3 L of
fluid, only 1 L would be prepared initially, and this would likely consist of dextrose
5% and 0.2% NS (or greater). Approximately 15 mEq/L of potassium would be
added to the next liter of IV solution if the patient had a reasonable urine output.
The infusion rate should be calculated to provide one-third of the daily
maintenance fluid plus one-half of the deficit replacement during the first 8 hours.
The remainder of the maintenance fluid (adjusted for fever) and deficit replacement
should be administered during the next 16 hours. Usually, serum electrolytes are
monitored every 6 to 8 hours during rehydration therapy to ensure that appropriate
electrolytes are being provided. Usually, the concentration of serum electrolytes is
monitored frequently during fluid replacement therapy of deficits. In general, the
serum sodium concentration should not be increased by more than 10 to 12
mEq/L/day. After the initial fluid deficits are replaced, the infusion rate of the IV
fluid would be decreased to 48 mL/hour (1,152 mL or approximately maintenance
Dehydration Associated with Diarrhea
Pulse, 110 beats/minute (normal, 80–160 beats/minute)
Respirations, 45 breaths/minute (normal, 20–40 breaths/minute)
BP, 100/58 mm Hg (normal, 75–105 mm Hg systolic and 40–65 mm Hg diastolic)
Blood urea nitrogen (BUN), 22 mg/dL
Correlate S.B.’s history and physical findings with the reported laboratory values.
Diarrheal fluid losses commonly contain high concentrations of bicarbonate,
accounting for S.B.’s metabolic acidosis. This, in turn, has resulted in a rapid
respiratory rate as the body attempts to compensate for the acidosis by eliminating
carbon dioxide. The increased insensible water losses of fever and tachypnea have
resulted in the loss of water in excess of sodium, producing hypernatremia.
CASE 103-3, QUESTION 2: How should S.B.’s dehydration be managed?
S.B. has relatively normal vital signs and will not require rapid fluid replacement
to correct hypotension. Hypernatremia in S.B. indicates fluid losses in excess of
sodium and this should be corrected. With hypernatremia, the central nervous system
(CNS) increases intracellular osmolarity load to prevent intracellular dehydration of
cells in the CNS. Rapid correction of hypernatremia can cause excessive movement
of water into the cells of the CNS and has been associated with seizures. Therefore,
S.B.’s fluid and electrolyte deficits should be corrected over the course of 2 to 3
days at a consistent rate, rather than rapidly. In general, serum sodium should not be
decreased more than 2 mEq/hour (maximum, 15 mEq/L/day).
S.B.’s requirements are estimated using the same methods described previously.
First, the approximate extent of dehydration must be estimated. S.B.’s weight of 6 kg
at the time of his well-child visit at 3 months of age was at the 50th percentile. If his
growth has continued at this rate, his current pre-illness weight should be
3 This weight should be used to calculate his maintenance
requirements. Thus, his water deficit is approximately 0.6 L, or 9%. Using this
approximation, his fluid and electrolyte requirements can be estimated as follows.
As discussed in Case 103-2, Question 2, the serum potassium value of 3.3 mEq/L
may not be indicative of S.B.’s total body potassium status. A metabolic acidosis in
S.B. should have facilitated the movement of hydrogen ions into the cells and the
movement of potassium from the intracellular to the extracellular space. Thus, the
serum potassium of 3.3 mEq/L probably indicates a total body deficit. Therefore, a
maintenance potassium dosage of 13 to 20 mEq/day (approximately 2 to 3 mEq/kg)
of potassium should be added to the intravenous fluid. Serum electrolytes should be
measured every 8 to 12 hours, and the intake of all electrolytes should be readjusted
With metabolic acidosis, bicarbonate should be administered as well. No
maintenance amount is customarily given, but deficit replacement is calculated in a
manner similar to that used for sodium (Table 103-3). The volume of distribution of
bicarbonate is 0.5 L/kg. For S.B., the bicarbonate deficit is as follows:
Initially, about half this amount should be added to the intravenous fluid and
replaced during the first 8 to 12 hours. His serum electrolytes then should be
reassessed, and the dosages adjusted accordingly. The entire bicarbonate deficit need
not be replaced at once because other compensatory mechanisms will contribute to
endogenous bicarbonate sparing.
CASE 103-3, QUESTION 3: Recommend an appropriate replacement fluid for S.B.’s therapy.
S.B.’s fluid and electrolyte maintenance requirements and deficits should be
corrected with dextrose 5% and approximately 0.2% NS with half as the chloride
. An infusion of this solution at 43 mL/hour should correct
approximately one-half the calculated fluid and bicarbonate deficits within 24 hours
in addition to his normal daily doses. After he urinates, 15 mEq/L KCl can be added
to the next liter of solution to provide approximately 2.6 mEq/kg/day to this patient.
The concentration of serum electrolytes should be measured often, and the
concentration of electrolytes in the replacement fluid should be adjusted every 8 to
12 hours based on laboratory results. The amount of fluid replacement should be
modified based on whether this patient’s diarrhea has resolved and fever has
Rehydration of the dehydrated patient may be achieved by either the oral or
intravenous route. In some patients, vomiting may preclude effective oral rehydration.
If the losses are diarrheal and no problem with vomiting exists, the oral route may be
a cost-effective alternative to the parenteral route. Various solutions have been used
to rehydrate children orally. In an asymptomatic dehydrated child, the sodium
concentration of an oral rehydration fluid should contain at least 70 mEq/L of
The composition of several products is shown in Table 103-4. A glucose
concentration of 2% optimizes water and electrolyte absorption from the GI tract
more concentrated glucose solutions can worsen rather than ameliorate diarrhea. Use
of the oral route and the more concentrated sodium solutions may allow safe
rehydration of hypernatremic dehydration in a shorter time frame than the 2 to 3 days
Caloric requirements of infants can be estimated using the formula provided in Table
103-1. The American Heart Association has suggested that infant feeding be divided
In the nursing period, only liquids are provided. During the
transitional period, solid foods are introduced, but human milk, or commercially
prepared infant formula, still provides the major source of the infant’s caloric and
nutrient supply. In the modified adult period, most nutrition is derived from the solid
foods consumed by other household members.
At birth, the human GI tract is adapted for the consumption of a human milk-based
diet. Intestinal lactase is present from 36 weeks’ gestation and exhibits its maximal
activity during infancy. Pancreatic amylase secretion is low, and the bile salt pool is
decreased relative to that of older persons, resulting in decreased fat absorption.
Human milk provides nutrients in their most usable form for the developing GI tract.
nutritional implications of this decision for M.E.?
Human milk is the ideal food for a human infant and should be encouraged to be
continued for the first year of life as long as mutually desired by both mother and
7 There are three phases to human milk production. During the first 5 days of
lactation, a viscous, yellow liquid known as colostrum is produced. Colostrum is
rich in protein, minerals, and other substances (e.g., immunoglobulins). During the
next 5 days, transitional milk is produced; in the last phase, mature human milk is
produced. The exact nutritional content of human milk varies from mother to mother;
however, mature human milk provides sufficient protein, minerals, and calories
regardless of the mother’s nutritional status. Mature human milk generally provides
70 kcal/100 mL, and fat accounts for more than 50% of the caloric content.
human milk is highly digestible and absorbable.
8 An additional 40% of calories is
provided as carbohydrates, primarily in the form of lactose, and the remaining 10%
is provided as protein. Whey and casein are the two primary proteins in mature
human milk, with whey being the major protein component (whey-to-casein ratio of
9 Human milk is of such biologic quality and bioavailability that adequate
growth can be attained with a lower overall intake of protein than is provided by
commercially prepared infant formulas, which contain lower whey-to-casein ratios.
The iron content of human milk is inadequate for term infants; however,
supplementation generally is unnecessary in the breast-fed infant.
maternal status, the vitamin D content of human milk is inadequate. Thus, M.E. will
require 400 international units of vitamin D while she is exclusively breast-fed.
Additionally, human milk provides the infant with protection against a wide
variety of infectious diseases, including otitis media, diarrhea, pneumonia, and
bronchiolitis. Evidence further suggests that human milk provides protection against
contains immunologically active cellular components and antibodies. These include
secretory IgA, both T and B lymphocytes, macrophages, and neutrophils.
lipases and amylase present in human milk may facilitate digestion of fat and
carbohydrates in the still developing GI tract. Proteins present in human milk serve
as carriers for trace minerals and facilitate their absorption.
glycopeptides may promote the colonization of the GI tract by Lactobacilli and
decrease colonization by Bacteroides, Clostridia, enterococci, and gram-negative
rods, all of which may be pathogenic.
Composition of Oral Rehydration Products
Product Na+ (mEq/L) K+ (mEq/L) Cl− (mEq/L)
Enfalyte 50 25 45 34 citrate 3
Rehydralyte 75 20 65 30 citrate 2.5
Pedialyte 45 20 35 30 citrate 2.5
WHO salts 75 20 65 10 bicarbonate 2
WHO, World Health Organization.
CASE 103-4, QUESTION 2: What potential complications are associated with breast-feeding? What
instructions should be given to M.E.’s mother?
Complications associated with breast-feeding are few; however, there are some
potential problems. “Breast milk jaundice” associated with an indirect
(unconjugated) hyperbilirubinemia can occur in the breast-fed infant during the first
week of life and generally resolves by the fourth week of life. Although the infant’s
skin, sclera, and palate become yellow, this is generally not a dangerous condition.
Nevertheless, if the bilirubin level becomes too high, the infant could develop an
encephalopathy known as kernicterus. However, it is generally not necessary for the
mother to stop breast-feeding while the infant has jaundice. The American Academy
of Pediatrics (AAP) recommends that infants nurse at least 8 to 12 times daily while
12 Some maternal infections have the potential to be transmitted to the
maternal infections with these viruses are contraindications to breast-feeding.
Other viruses, such as herpes simplex virus, can be transmitted if contact with active
lesions occurs during breast-feeding. Similarly, some medications taken by the
mother are detectable in her breast milk. Only a few agents (e.g., antineoplastics,
radiopharmaceuticals, ergot alkaloids, iodides, atropine, lithium, cyclosporine,
chloramphenicol, bromocriptine), however, are absolute contraindications to breastfeeding.
CASE 103-4, QUESTION 3: M.E.’s mother suffers from migraine headaches, which have increased in
frequency since M.E.’s birth. M.E.’s mother takes an ergot alkaloid for the acute management of her
these products prepared and how do they differ from human milk?
Because of the excretion of ergot alkaloids into breast milk and the risk for toxicity
to the infant, it is advisable to either select an alternative medication or discontinue
breast-feeding and use an infant formula. Examples of infant formulas are provided in
Table 103-5. According to AAP guidelines for commercially prepared infant formula
composition, formula should provide 20 kcal/ounce, osmolality should be between
300 and 400 mOsm/L, protein quantity should be a minimum of 1.8 g/100 kcal and
should not exceed 4.5 g/100 kcal, and fat quantity should be between 3.3 and 6 g/100
kcal, supplying between 30% and 54% of calories. Infant formulas generally begin
with a cow’s milk base; however, intolerance to pure cow’s milk has resulted in
several modifications. The predominant protein in cow’s milk is casein, which is
more difficult for infants to digest than the human milk protein, whey. Consequently,
infant formulas generally have less casein than cow’s milk, although not to the level
replaced by one of several vegetable oils, allowing for easier digestion. Last, the
carbohydrate source in cow’s milk-based formula is supplemented with lactose or
sucrose because the lactose content of cow’s milk is only 50% to 70% of that in
human milk. Soy-based and protein hydrolysate formulas are available for infants
who are intolerant of cow’s milk-based formulas.
Soy-based formulas use soybean as the protein source.
enhance protein digestibility and improve the bioavailability of some nutrients.
Although nutrients, such as methionine, zinc, and carnitine, are still present, their
concentrations are relatively low. Therefore, the manufacturer routinely adds
methionine to all soy-based formulas. Zinc and carnitine may not be added, and
exogenous supplementation may be necessary. Soy-based formulas substitute sucrose,
corn syrup, or a combination of the two for lactose as the carbohydrate source.
Additionally, soy protein formulas are more expensive than cow’s milk-based
formulas. The AAP recommends that the use of soy-based formula be limited to
patients with primary lactase deficiency (galactosemia), patients with secondary
lactose intolerance from enteric infections or other causes, vegetarian families in
which animal protein formulas are not desired, and infants who are potentially cow’s
milk protein allergic, but who have not demonstrated clinical manifestations of
allergy. Long-term use of soy-based formulas in premature and low-birth-weight
infants should not be recommended. Soy-based formulas have aluminum
contamination and have been associated with the development of rickets. Soy-based
formulas are also not recommended for infants with documented allergic reactions to
cow’s milk protein because of the potential for cross-antigenicity between the two
proteins. Additionally, soy protein formulas are not recommended for the routine
Elemental formulas, made with hydrolysate formulas, are another option for infants
who are intolerant of cow’s milk-based formulas. The milk proteins (i.e., casein and
whey) are heat-treated and enzymatically hydrolyzed to enhance digestibility of
protein hydrolysate formulas, which are fortified with additional amino acids that are
lost during processing. As with soy protein formulas, protein hydrolysates substitute
sucrose, tapioca, or corn syrup for lactose as the carbohydrate source. Protein
hydrolysate formulas often include significant amounts of medium-chain triglycerides
because they are easily absorbed. Because the proteins are extensively hydrolyzed,
these formulas probably are the least allergenic of the infant formulas and, therefore,
may be appropriate for infants with true allergy to cow’s milk protein. Nevertheless,
prospective studies on the safety of such a substitution in human infants have not been
undertaken because it would be unethical to intentionally expose infants with
documented allergies to a potential allergen. Protein hydrolysate formulas are the
least palatable of the available pediatric formulas and are more costly than other
Protein Hydrolysate, Elemental,
Enfamil with iron Isomil Alimentum
Similac with iron Nursoy Nutramigen
Gerber Good Start ProSobee Pregestimil
Gerber Soy Plus Neosure Advance
Similac Sensitive Enfamil Premature
Infant formula is available from the manufacturers in three forms: ready-to-feed
formula, powder for reconstitution, and concentrated liquid. The ready-to-feed form
is the most convenient but also the most expensive. The powder and the concentrated
liquid are less expensive; however, both require that predetermined amounts of
boiled water be added before use. To save money, some parents will dilute infant
formula to a greater extent than is recommended to make the formula last longer. This
practice should be discouraged because excessive free water intake by infants
younger than 1 year of age may result in hyponatremia and, ultimately, seizures.
Similarly, supplementing an infant’s diet with free water, for whatever reason, may
also result in hyponatremia and seizures and should be discouraged. Periodically,
manufacturing problems can occur, resulting in the recall of a product from the
15 Therefore, it is important for the patient’s healthcare providers to stay
abreast of manufacturers’ recalls.
Introduction of Pure Cow’s Milk
CASE 103-4, QUESTION 4: At 2 months of age, M.E. is found to have a hematocrit (Hct) of 33% (normal,
Pure cow’s milk, straight from the dairy counter in the grocery store, is not
recommended for infants younger than 1 year of age. Unlike human milk, the iron in
cow’s milk is present in inadequate concentrations and absorbed poorly from the
human GI tract. For this reason, most infant formulas are fortified with iron. Cow’s
milk has been associated with GI blood loss in infants younger than 140 days of
16 When the milk is heated to a higher temperature than the usual pasteurization
temperature, as it is in formula preparation, the association of cow’s milk with GI
bleeding is no longer present; therefore, the component responsible for the blood loss
appears to be a heat-labile protein. Furthermore, cow’s milk contains excessive
amounts of solute that cannot be eliminated by the immature kidney. Also, cow’s milk
does not contain taurine, an amino acid that is important in retinal development.
To treat M.E.’s anemia, iron should be added to her diet. This can be done by
changing back to an iron-fortified infant formula, feeding her an iron-fortified cereal,
or giving a therapeutic ferrous sulfate liquid medication. The appropriate iron
replacement dose for severe anemia is 4 to 6 mg/kg/day of elemental iron in divided
doses with follow-up of the infant’s hemoglobin and hematocrit.
into M.E.’s diet. How should the clinician respond?
Human milk or commercially prepared infant formula provides adequate nutrition
for an infant for the first 12 months of life. Introduction of solid foods before the age
of 4 months, although common in the past, is discouraged because the younger infant
is unprepared to swallow foods other than liquids. Solids (first cereals, then fruits,
and vegetables) should be introduced when the child has good control of the head and
neck movements (i.e., usually at the age of 4–6 months).
should be introduced at a time, at 1-week intervals, to allow assessment of food
QUESTION 1: L.B. is a 2-week-old infant whose newborn screen is positive for phenylketonuria (PKU).
with inborn errors of metabolism. How should L.B.’s diet be modified?
Inborn errors of metabolism are disorders in which an enzyme or its cofactor is
absent or insufficient to meet metabolic demands.
precursor compounds in a metabolic pathway can accumulate before the defective
step. Correspondingly, one or more metabolic products that normally would have
been generated after the defective step in the metabolic pathway are not sufficiently
The dietary management of metabolic errors is based on the following strategies:
Reduce the intake of a precursor compound that cannot be metabolized.
Supplement the deficient compounds that would have been produced if the normal
metabolic pathway had not been blocked.
Add a substrate that provides an alternative pathway for elimination of an
Therapeutic formulas are designed to reduce the intake of precursor compounds or
to provide the deficient metabolic end product.
When hydroxylation of phenylalanine to tyrosine does not take place,
phenylalanine accumulates in the blood and results in mental retardation. Because
PKU has been diagnosed in L.B., his diet should be modified using a formula
containing little or no phenylalanine. The tyrosine deficiency of PKU also can be
managed by the addition of tyrosine to the phenylalanine-free therapeutic formulas
that are available for patients with PKU. When L.B. progresses to solid foods, it will
be important to limit or avoid foods that contain high levels of protein such as eggs
Other metabolic errors present in infancy include galactosemia (galactose cannot
be metabolized to glucose), homocystinuria (methionine is not converted to cysteine),
urea cycle disorders (ammonia detoxification is impaired), and maple syrup urine
disease (metabolism of the branched-chain amino acids leucine, isoleucine, and
These metabolic errors are managed by manipulating the diet.
the carbohydrate source should not contain galactose
or lactose. In homocystinuria, methionine should be present only in quantities
sufficient to meet basic requirements, and cysteine should be supplemented. In the
urea cycle disorders, protein often is provided only as essential amino acids, and a
high-energy diet is provided to maximize the formation of nonessential amino acids
from nitrogen and to minimize ammonia production. In maple syrup urine disease,
natural protein is fed in small quantities to provide the minimal requirement of
branched-chain amino acids, and a branched-chain amino acid-free supplement is
added to provide adequate protein intake.
Nutritional support using the GI tract is the preferred approach when possible.
Enteral nutrition provides several advantages. First, interposition of the GI mucosa
between the nutrient supply and the circulation allows absorptive function to provide
a homeostatic control. Second, the flow of nutrients from the GI tract to the liver via
the portal circulation before reaching the systemic circulation also assists
homeostatic control. Third, the lack of enteral nutrition allows normal GI tract flora
to overgrow and translocate into the blood, ultimately resulting in bacteremia.
Finally, the intestinal mucosa depends on intraluminal absorption for much of its
energy supply. Hence, provision of at least a small amount of enteral feeding,
referred to as trophic feeds, helps to ensure a healthy GI tract and may facilitate
advancement to full enteral feedings at the appropriate time.
Normal oral feeding is the most basic method for patients who are willing and
able to eat or drink. Patients whose GI motility, structure, and function are normal but
whose oral feeding is prevented by an altered state of consciousness, uncoordinated
sucking and swallowing, or other conditions that prevent adequate oral ingestion can
be fed by a GI tube in intermittent boluses or by continuous infusion.
Bolus tube feedings more closely mimic the normal state. They periodically
distend the stomach, which aids in gastric secretion and emptying. When bolus tube
feeding is undertaken, the volume of formula or expressed breast milk required to
provide sufficient calories for a 24-hour period is administered through the tube in
equal aliquots every 2, 3, 4, or 6 hours. The frequency of administration depends on
the patient’s age, gastric capacity, and the infant’s ability to maintain a normal serum
glucose concentration between feedings. In general, younger and more premature
infants require more frequent feedings. Intolerance to bolus tube feedings can be
manifested as diarrhea, gastroesophageal reflux with emesis, or poor motility. Poor
motility usually is apparent when large volumes of feeding, referred to as residuals,
remain in the stomach when the next feeding is due.
Continuous tube feedings can be given at a constant rate of infusion by pump into
the stomach or duodenum when bolus feedings have failed. This approach may be
better tolerated by premature infants and children with diarrhea.
Patients with intrinsic GI disease (Table 103-6) or malabsorption may require
total or supplemental PN. Concurrent administration of low-volume, trophic enteral
feedings may provide important nutrients to the gut mucosa even when the parenteral
route supplies all of the necessary systemic nutrients.
18 Administration of PN into a
peripheral vein is limited to those patients expected to require parenteral feeding
only for a short time (i.e., 2 weeks) because the amount of nutrients that can be safely
infused peripherally is limited. In patients who require long-term PN, the IV solution
is more concentrated and must be administered into a central vein.
his diarrhea and weight loss and for fluid and nutritional management.
Weight, 6.5 kg (50th–75th percentile)
Length, 62 cm (50th percentile)
Albumin, 3.8 g/dL (normal, 4–5.3 g/dL)
Prealbumin, 7 mg/dL (normal, 20–50 mg/dL)
How would you assess T.C.’s nutritionalstatus?
Growth assessment is an important focus of pediatric health care, especially
during the first year of life. With the exception of the intrauterine period, the most
rapid growth occurs during the first year. On average, a normally growing infant
gains approximately 30 g/day. Typically, healthy infants weigh approximately 3 times
their birth weight by their first birthday.
The patient’s nutritional status should be assessed before beginning a nutritional
support regimen and reassessed at regular intervals during the course of treatment. If
the patient previously was well nourished, the goal is to maintain that status until a
normal diet can be resumed. In a child who was previously malnourished, an effort
should be made to promote “catch-up” growth and to normalize the biochemical
nutritional measures. One in five children admitted to the hospital experience acute
19 Malnutrition in children is a risk factor for decreased
social skills and impaired intellectual development.
Factors used to determine nutritional status in children include dietary history,
weight, height, and visceral protein measurements (e.g., albumin, prealbumin). Other
measurements used in adults, such as 24-hour creatinine excretion, 24-hour nitrogen
excretion, and nitrogen balance, are reserved for older children because complete
collections of urine are difficult to obtain and because the percentage of non-urea
nitrogen present in urine is variable in infants.
Anthropometric measurements can also be used to assess T.C.’s nutritional status.
Height, weight, and head circumference are used to determine nutritional status in
infants and children. Standards for these measurements have been derived from
pediatric patients in the United States and compiled into graphs referred to as growth
curves (http://www.cdc.gov/growthcharts).
3 An individual patient’s measurements
are compared with the graph of normal values for that specific age group. As
prematurely born infants age, a standard growth curve adjusted for prematurity can be
used. Using these measurements, comparisons with standards are possible: weight
for age, height for age, and weight for height.
3 A weight that is below the fifth
percentile for the patient’s height is considered an indication of acute malnutrition.
Similarly, a height and weight that are below the fifth percentile for the patient’s age
indicate chronic malnutrition. It is important to consider the height and weight of the
child’s parents because genetics are important determinants of the height and weight
that a child may ultimately achieve. Additionally, the revised growth charts include
the body mass index (BMI) for age for children older than 2 years. The BMI helps
identify children at risk for obesity and type 2 diabetes, two problems that have
recently become concerns in children.
Common Indications for Parenteral Nutrition Support
Omphalocele (herniation of viscera into the umbilical cord base)
Gastroschisis (defect of abdominal wall, any location except umbilical cord)
Congenital diaphragmatic hernia
Abdominal trauma involving viscera
Adverse effects of treating neoplastic disease
Stomatitis, glossitis, and esophagitis
aOther indications for parenteral nutrition may exist.
Numerous biochemical indices are also used in the assessment of nutritional status.
Of these, the most readily available and widely used is the serum albumin
19 makes it an insensitive indicator for
developing and resolving malnutrition.
Prealbumin can also function as a biochemical marker of nutritional status.
Because of its shorter half-life, prealbumin has the advantage of being more sensitive
than albumin to acute nutritional changes, and it is still useful when exogenous
should T.C.’s enteral diet be initiated?
A prompt decrease in stool output when enteral intake is stopped is typical of
infants with chronic diarrhea. Nonetheless, evaluation of bowel function and
adaptation has shown that enteral nutrition is superior to PN with regard to histologic
recovery, improvement of D-xylose absorption, protein absorption, and
In fact, improvement in histology or absorptive function
might not occur until enteral nutrients are given.
18 Thus, for T.C., every effort should
be made to provide some nutrition enterally.
The enteral regimen should be initiated with a lactose-free formula, such as an
elemental formula or a soy-based formula. Although any soy-based formula would be
appropriate, Isomil DF is a soy-based formula with added fiber that is indicated for
infants with diarrhea. Infants with chronic diarrhea can have small bowel mucosal
damage and decreased disaccharidase activity.
4 Carbohydrate absorption depends on
digestion of disaccharides and polysaccharides to monosaccharides through
disaccharidase activity in the intestinal lumen. Substitution of free glucose orally may
overcome the problem of carbohydrate digestion and absorption. Administration of
large amounts of oral glucose should be limited, however, because of its osmotic
effect and potential to worsen diarrhea. Furthermore, incompletely absorbed
carbohydrate is available to colonic bacteria for fermentation, the end products of
which can produce diarrhea through colonic irritation.
Unlike carbohydrate, protein rarely causes diarrhea, but the mucosal damage
present in patients with chronic diarrhea, such as T.C., can reduce the absorptive
surface area so that protein malabsorption may occur. This can be minimized through
the administration of a formula containing protein in the form of dipeptides and
tripeptides, which are absorbed more efficiently than free amino acids.
Dilution of hypertonic formulas to half strength may improve formula tolerance.
The concentration is increased in a stepwise fashion to full strength if there is no
carbohydrate malabsorption and if stool output is not excessive. Tolerance may be
improved by continuous infusion of the enteral product. If enteral refeeding results in
the return of diarrhea, fluid and electrolytes must be replaced with an equal volume
of an IV solution of similar electrolyte composition to the stool loss.
Malabsorption or formula intolerance can be assessed by stool studies, which
would include assessing for the presence of reducing substances and stool pH.
Lactose is a reducing sugar and its presence in stool is an assessment of carbohydrate
absorption. The bacterial fermentation products of malabsorbed carbohydrates can
result in a decreased stool pH, which suggests malabsorption. To further evaluate
carbohydrate absorption, D-xylose may be given orally; a blood sample is drawn 4 to
5 hours later to determine the amount absorbed. This test may be of initial prognostic
value in predicting which patients will require prolonged courses of treatment.
More than 5% of ingested fat in a stool collection (typically obtained for 3 days) is
indicative of fat malabsorption. All these tests can be evaluated during outpatient
visits to guide the refeeding process.
Once the diarrhea has resolved, standard infant formula feedings should be
established using an enteral elemental or soy-based formula. Regardless of the time
chosen, a gradual stepwise conversion is suggested. A small volume of standard
substituted for an equal volume of elemental or soy-based formula, and the
substitution volume is increased daily until the elemental or soy-based formula is
eliminated completely from the regimen. If a specific nutrient intolerance has been
identified, a standard formula that does not contain that nutrient must be selected. For
example, a patient with cow’s milk protein intolerance may require a soy protein
formula or an elemental formula.
Pediatric Parenteral Nutrition
The basic requirements for a parenteral nutrient regimen are listed in Table 103-1.
These guidelines for the initiation of a nutrient regimen should be individualized to
specific patient needs. The correct regimen for any specific patient is that which
supplies sufficient nutrients to promote a normal rate of growth without toxicity. In
particular, patients with ongoing, abnormal nutrient losses may require much larger
doses of certain nutrients. Individualization of the nutrient prescription cannot be
overemphasized. Many of the requirements listed in Table 103-1 apply to nutrients
administered by the enteral route as well. In some instances, the absorption of a
particular nutrient from the GI mucosa is incomplete, and enteral requirements are
substantially higher. This is particularly true of the major minerals (calcium,
magnesium, and iron) and trace elements.
Parenteral nutrition is indicated for any infant or child unable to take in sufficient
nourishment to maintain normal growth. Some specific indications are listed in Table
Extremely premature or VLBW infants require specialized nutritional support for two
distinct reasons. First, the third trimester in utero is a time of rapid growth and
accumulation of protein, glycogen, fat, and minerals.
22 The infant born in the very
early stages of the third trimester does not accumulate these stores and, therefore,
must receive nutrients earlier than a more mature infant. Second, extreme prematurity
is associated with poor coordination of the suck and swallow reflex, poor GI
motility, and incomplete absorption. Therefore, enteral nutrients may need to be
administered via an orogastric or nasogastric tube, and PN supplementation probably
will be needed. PN, especially of amino acids, should be initiated soon after birth to
duplicate intrauterine growth and prevent a catabolic state in the first few days of
life. The fetus has a continuous supply of amino acids that is immediately stopped
23 A standardized solution containing amino acids and dextrose
can be used for infants weighing less than 1 kg in the first 24 hours of life. There has
been some reluctance to administer amino acids this soon after birth because of
increased risk of hyperammonemia, uremia, and metabolic acidosis. Several studies,
however, have shown early introduction of amino acids is safe, provides a positive
nitrogen balance, and promotes better health outcomes.
Respiratory distress may preclude the ability to consume sufficient nutrients enterally
because high respiratory rates prevent coordinated breathing and swallowing. In
infants who are hypoxic, or at high risk for hypoxia, aggressive enteral feedings
during the acute phase of their illness can increase the likelihood of bowel ischemia.
Often, these situations are resolved in 3 to 5 days, but this can rarely be predicted at
the outset. Trophic feedings (1–5 mL/hour) are often implemented to maintain GI
tract integrity. Nutritional support in such cases is initiated by giving parenteral
fluids, which provide dextrose as a caloric source. This allows the infant to conserve
endogenous energy substrates, an important consideration for the VLBW infant whose
entire body composition may contain as little as a 3- to 4-day energy supply.
should be initiated as soon as it becomes clear the enteral feeding will not be
possible for at least 3 to 5 days, or when several days have elapsed and no clear time
frame can be determined for the establishment of enteral feeding. Although a short
course (5 days or less) of PN may be used, the quantity of nutrients supplied during
the process of initiation and gradual increase to full requirements is so low that
extremely short courses may be difficult to justify. Peripheral PN using fat emulsion
as a significant source of calories, however, can provide up to 70 kcal/kg and, with
appropriate types and amounts of protein, result in modest weight gain and nitrogen
Infants with GI anomalies often require PN because the implementation of enteral
feedings may be delayed. For example, GI tract atresia or stenosis can obstruct, or
partially obstruct, the lumen of the GI tract. This prevents or slows the passage of
fluids and nutrients and can result in vomiting, depending on the location of the
obstruction. Similarly, infants with necrotizing enterocolitis have zones of ischemic
bowel and are at risk for bowel perforation if fed enterally.
disorders need PN until the viability of the entire GI tract can be assured.
CHRONIC RENAL FAILURE AND HEPATIC DISEASE
Chronic renal or hepatic disease requires modification of a normal diet to account for
the impaired elimination of nitrogenous waste or impaired protein metabolism.
Careful caloric supplementation with a reduced amount of protein may permit normal
growth while minimizing excess urea production in an infant with renal failure.
of his disease may alter specific nutrient needs?
When initiating PN, the protein (amino acids), glucose (dextrose), fat (lipids or fat
emulsion), fluid, and electrolyte, mineral, and vitamin components of the regimen are
managed as separate entities. In addition, the route of PN delivery is important to
consider because the amount of glucose, potassium, and calcium must be limited if
the infusion is given peripherally. In general, 12.5% dextrose, 40 mEq/L potassium,
and 10 mEq/L calcium are the maximal amounts that should be provided by infusion
into a peripheral vein. These nutrients can be increased if a central venous catheter is
placed. The fluids, electrolytes, minerals, and vitamins are initiated at full daily
maintenance doses after correction of any preexisting abnormalities. Protein should
be initiated at full daily doses in term infants and children with normal renal and
hepatic function. Glucose and fat are started at lower doses and increased daily until
Protein should be started in T.C. at full daily requirements of 2 to 3 g/kg/day.
Azotemia and acidosis have occurred in infants receiving more than 4 g/kg/day of
protein; however, these complications are rare at the recommended dosage.
Parenteral glucose administration is initiated at 5 to 8 mg/kg/minute (7.2–11.5
g/kg/day). At normal maintenance fluid rates, 10% dextrose represents a generally
well-tolerated starting solution for patients of virtually any age or size, except the
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