Nutrition
Diane M. Anderson
Brenda B. Poindexter
Camilia R. Martin
KEY POINTS
Human milk is the best nutrition for term and premature infants.
Early nutrition influences childhood growth and neurodevelopment.
Growth assessment is essential to ensure optimal nutrition.
Following birth, term infants rapidly adapt from a relatively constant intrauterine supply of nutrients to intermittent feedings of milk. Preterm infants, however, are at increased risk for nutritional compromise. These infants are born with limited nutrient accretion and reserves due to their premature delivery, immature metabolic pathways, and increased nutrient demands. In addition, medical and surgical conditions commonly associated with prematurity have the potential to alter nutrient requirements and complicate adequate nutrient delivery. As survival for these high-risk newborns continues to improve, current data suggest that early nutrition can improve both short- and long-term outcomes.
I. GROWTH
A. Fetal body composition changes throughout gestation, with accretion of most nutrients occurring primarily in the late second and throughout the third trimester. Term infants will normally have sufficient glycogen and fat stores to meet energy requirements during the relative starvation of the first days after birth. In contrast, preterm infants will rapidly deplete their limited nutrient reserves of glycogen and nitrogen, becoming both hypoglycemic and catabolic unless appropriate nutritional therapy is provided. In practice, it is generally assumed that the severity of nutrient insufficiency is inversely related to gestational age at birth and birth weight.
B. Postnatal growth varies from intrauterine growth in that it begins with a period of weight loss, primarily through the loss of extracellular fluid. The typical postnatal weight loss in the term infant is 5% to 10% of birth weight. Historically, in preterm infants, this postnatal weight loss can be as much as 15% of birth weight, with the nadir by 4 to 6 postnatal days and a regain to birth weight by 14 to 21 days. This postnatal weight loss pattern, however, can be attenuated in most preterm infants with optimized, early nutrition. Although currently, there is no widely accepted measure of neonatal growth that captures both the weight loss and subsequent gain characteristic of this period, in general, the goals in practice are to limit the degree and duration of initial weight loss in preterm infants and to facilitate regain of birth weight within 7 to 10 postnatal days.
C. After achieving birth weight, intrauterine growth and nutrient accretion rate data are used as reference standards for assessing growth and nutrient requirements for the growing preterm infant. Goals for weight gain are 15 to 20 g/kg/day for infants <2 kg and 20 to 30 g/day for larger infants. Approximately 1 cm/week in length and 1 cm/week in head circumference are used as a goal for growth in these parameters. Although these goals may not be initially attainable in some ill preterm infants, replicating growth of the fetus at the same gestational age remains an appropriate goal as recommended by the American Academy of Pediatrics (AAP). Efforts to minimize cumulative postnatal nutrient deficits begin in the first postnatal days and require a combined approach with parenteral and enteral nutrition.
D. Serial measurements of weight, head circumference, and length plotted on growth curves provide valuable information in the nutritional assessment of the preterm infant. Gender-specific growth charts are available based on intrauterine growth curves for weights, lengths, and head circumferences. The Revised Fenton growth charts1 combine intrauterine growth with the World Health Organization (WHO) chart to construct a growth chart from 22 to 50 weeks’ postmenstrual age (PMA). Preterm growth is taken from six countries, and the growth curve is smoothed from the preterm to the term WHO curve. The smoothing reflects the rapid growth demonstrated by preterm infants (Figs. 21.1A,B). The Olsen growth curves2 are drawn from a large, contemporary, racially diverse U.S. sample (Figs. 21.2A-D). Infants can be plotted from 23 to 42 weeks’ PMA on gender-specific weight, length, and head circumference curves. Postnatal growth curves and body mass index (BMI) curves are also available. Postnatal growth curves follow the same infants over time (i.e., longitudinal growth curves) and are available from a number of single-NICU studies and from the National Institute of Child Health and Human Development (NICHD) multicenter study (2000). These curves, however, show actual, not ideal growth. Intrauterine growth remains the gold standard for comparison.
E. When an infant is in full-term-corrected gestational age, the Centers for Disease Control and Prevention (CDC) recommends the WHO Child Growth Standards 2006 be used for monitoring of growth. Infants should be plotted by corrected age and followed for catch-up growth. The charts can be downloaded from http://www.cdc.gov/growthcharts/who_charts.htm.
II. NUTRIENT RECOMMENDATIONS
A. Sources for nutrient recommendations for preterm infants include the American Academy of Pediatrics, Committee on Nutrition (AAP-CON), the European Society for Paediatric Gastroenterology, Hepatology and Nutrition Committee on Nutrition (ESPGHAN-CON), and in the textbook Nutritional Care of Preterm Infants: Scientific Basis and Practical Guidelines (page 298) (Table 21.1). These recommendations are based on (i) intrauterine accretion rate data, (ii) the nutrient content of human milk, (iii) the assumed decreased nutrient stores and higher nutritional needs in preterm infants, and (iv) the available data on biochemical measures reflecting
adequate intake. However, due to the limitations of the currently available data, the goals for nutrient intake for preterm infants are considered to be recommendations only.
adequate intake. However, due to the limitations of the currently available data, the goals for nutrient intake for preterm infants are considered to be recommendations only.
 Figure 21.1. A: Fenton growth chart for girls. (From Fenton TR, Kim JH. A systematic review and meta-analysis to revise the Fenton growth chart for preterm infants. BMC Pediatr 2013; 13:59. http://www.ucalgary.ca/fenton. Accessed June 23, 2016.) |
 Figure 21.1. B: Fenton growth chart for boys. (From Fenton TR, Kim JH. A systematic review and meta-analysis to revise the Fenton growth chart for preterm infants. BMC Pediatr 2013; 13:59. http://www.ucalgary.ca/fenton. Accessed June 23, 2016.) |
 Figure 21.2. A: Olsen weight chart for girls. (Reproduced with permission from Olsen IE, Groveman S, Lawson ML, et al. New intrauterine growth curves based on United States data. Pediatrics 2010;125:e214-e224. http://www.nursing.upenn.edu/media/infantgrowthcurves/Documents/Olsen-NewIUGrowthCurves_2010permission.pdf. Accessed June 23, 2016. Copyright 2010 by the American Academy of Pediatrics. Data source: Pediatrix Medical Group.) |
 Figure 21.2. B: Olsen length and head circumference chart for girls. (Reproduced with permission from Olsen IE, Groveman S, Lawson ML, et al. New intrauterine growth curves based on United States data. Pediatrics 2010;125:e214-e224. http://www.nursing.upenn.edu/media/infantgrowthcurves/Documents/Olsen-NewIUGrowthCurves_2010permission.pdf. Accessed June 23, 2016. Copyright 2010 by the American Academy of Pediatrics. Data source: Pediatrix Medical Group.) |
 Figure 21.2. C: Olsen weight chart for boys. (Reproduced with permission from Olsen IE, Groveman S, Lawson ML, et al. New intrauterine growth curves based on United States data. Pediatrics 2010;125:e214-e224. http://www.nursing.upenn.edu/media/infantgrowthcurves/Documents/Olsen-NewIUGrowthCurves_2010permission.pdf. Accessed June 23, 2016. Copyright 2010 by the American Academy of Pediatrics. Data source: Pediatrix Medical Group.) |
 Figure 21.2. D: Olsen length and head circumference chart for boys. (Reproduced with permission from Olsen IE, Groveman S, Lawson ML, et al. New intrauterine growth curves based on United States data. Pediatrics 2010;125:e214-e224. http://www.nursing.upenn.edu/media/infantgrowthcurves/Documents/Olsen-NewIUGrowthCurves_2010permission.pdf. Accessed June 23, 2016. Copyright 2010 by the American Academy of Pediatrics. Data source: Pediatrix Medical Group.) |
Table 21.1. Comparison of Enteral Intake Recommendations and Selected Feeding Regimens* for the Preterm Infant | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
B. Fluid (see Chapters 13 and 23). The initial step in nutritional support is to determine an infant’s fluid requirement, which is dependent on gestational age, postnatal age, and environmental conditions. Generally, baseline fluid needs are inversely related to gestational age at birth and birth weight. During the first postnatal week, very low birth weight (VLBW) infants are known to experience increased water loss because of the immaturity of their skin, which has a higher water content and increased permeability, and the immaturity of their renal function with a decreased ability to concentrate urine. Environmental factors, such as radiant warmers, phototherapy, and incubators, also impact insensible losses and may affect fluid requirements. Conversely, restriction of fluid intake is often utilized for the prevention and/or treatment of patent ductus arteriosus, renal insufficiency, and bronchopulmonary dysplasia (BPD). Fluid requirements in the first few postnatal weeks are, therefore, continually reassessed, as the transition is made from fetal to neonatal life and at least daily afterward.
C. Energy. Estimates suggest that preterm infants in a thermoneutral environment require approximately 40 to 60 kcal/kg/day for maintenance of body weight, assuming adequate protein is provided. Additional calories are needed for growth, with the smallest neonates tending to demonstrate the greatest need, because their rate of growth is highest (Table 21.2). The three sources, AAP, ESPGHAN-CON, and Koletzko et al. recommend a range of 105 to 135 kcal/kg/day. Practice generally strives for energy intakes of 110
to 130 kcal/kg/day. Infants with severe and/or prolonged illness frequently require a range of 130 to 150 kcal/kg/day. Lesser intakes (85 to 100 kcal/kg/day) may sustain intrauterine growth rates, when parenteral nutrition (PN) is used.
to 130 kcal/kg/day. Infants with severe and/or prolonged illness frequently require a range of 130 to 150 kcal/kg/day. Lesser intakes (85 to 100 kcal/kg/day) may sustain intrauterine growth rates, when parenteral nutrition (PN) is used.
Table 21.2. Estimation of Energy Requirement of the Low Birth Weight Infant | |||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| |||||||||||||||||||||||||||||||||
III. PARENTERAL NUTRITION
A. Nutrient goals. The initial goal for PN is to provide adequate calories and amino acids to prevent negative energy and nitrogen balance. Goals thereafter include the promotion of appropriate weight gain and growth while awaiting the attainment of adequate enteral intake.
B. Indications for initiating parenteral nutrition. PN is started the first postnatal day for infants who are <1,500 g birth weight. For infants for whom significant enteral intake is not anticipated by 3 to 5 days of age or for those with cardiac disease requiring calcium supplementation, PN may also be considered.
C. Peripheral versus central parenteral nutrition
1. Parenteral solutions may be infused through a peripheral or central vein. Historically, the AAP has recommended that peripheral solutions maintain an osmolarity between 300 and 900 mOsm/L. Because of this limitation, peripheral solutions often cannot adequately support growth in extremely low birth weight (ELBW) infants. Central PN not only allows for the use of more hypertonic solutions but also incurs greater risks, particularly catheter-related sepsis. Umbilical venous catheters are commonly used for parenteral administration.
2. Central PN is considered to be warranted under the following conditions:
a. Nutritional needs exceed the capabilities of peripheral PN.
b. An extended period (e.g., >7 days) of inability to take enteral feedings, such as in infants with necrotizing enterocolitis (NEC) and in some postoperative infants
c. Imminent lack of peripheral venous access
D. Carbohydrate. Dextrose (D-glucose) is the carbohydrate source in intravenous (IV) solutions (see Chapter 24).
1. The caloric value of dextrose is 3.4 kcal/g.
2. Because dextrose contributes to the osmolarity of a solution, it is generally recommended that the concentration administered through peripheral veins be limited to ≤12.5% dextrose. Higher concentrations of dextrose may be used for central venous infusions. Infants receiving extracorporeal membrane oxygenation (ECMO) therapy may require up to 40% dextrose due to fluid restriction. The use of ultrafiltration with ECMO allows for an increase in fluid administration and a decrease in dextrose to 22% to meet the infant’s glucose needs.
3. Dextrose infusions are typically referred to in terms of the milligrams of glucose per kilogram per minute (mg/kg/minute) delivered, which expresses the total glucose load and accounts for infusion rate, dextrose concentration, and the patient’s weight (Fig. 21.3).
 Figure 21.3. Chart to quickly calculate glucose infusion rate in neonates. (From Chowning R, Adamkin DH. Table to quickly calculate glucose infusion rates in neonates. J Peri 2015;35:463.) |
4. The initial glucose requirement for term infants is defined as the amount that is necessary to avoid hypoglycemia. In general, this may be achieved with initial infusion rates of approximately 4 to 6 mg/kg/minute.
5. Preterm infants usually require higher rates of glucose because they have a higher brain-to-body weight ratio and higher total energy needs. Initial infusion rates of 4 to 8 mg/kg/minute may be required to maintain euglycemia.
6. Initial rates may be advanced, as tolerated, by 1 to 2 mg/kg/minute daily to a goal of 11 to 12 mg/kg/minute. This may be accomplished by increasing dextrose concentration, by increasing infusion rate, or by a combination of both. Infusion rates above 11 to 12 mg/kg/minute may exceed the infant’s oxidative capacity and are generally not recommended because this may cause the excess glucose to be converted to fat, particularly in the liver. This conversion may also increase oxygen consumption, energy expenditure, and CO2 production.
7. The quantity of dextrose that an infant can tolerate will vary with gestational and postnatal age. Signs of glucose intolerance include hyperglycemia and secondary glucosuria with osmotic diuresis.
E. Protein. Crystalline amino acid solutions provide the nitrogen source in PN.
1. The caloric value of amino acids is 4 kcal/g.
2. Three pediatric amino acid formulations are commercially available in the United States: TrophAmine (B. Braun), Aminosyn-PF (Hospira), and Premasol (Baxter). In theory, these products are better adapted to
the needs of newborns than are standard adult formulations because they have been modified for improved tolerance and contain conditionally essential amino acids. However, the optimal amino acid composition for neonatal PN has not yet been defined. The addition of cysteine is recommended because this amino acid may be conditionally essential in premature infants.
the needs of newborns than are standard adult formulations because they have been modified for improved tolerance and contain conditionally essential amino acids. However, the optimal amino acid composition for neonatal PN has not yet been defined. The addition of cysteine is recommended because this amino acid may be conditionally essential in premature infants.
3. It has been demonstrated that VLBW infants who do not receive amino acids in the first postnatal days catabolize body protein at a rate of at least 1 g/kg/day. Studies investigating the use of early amino acids have consistently shown a reversal of this catabolism without adverse metabolic consequences. Current recommendations support the infusion of amino acids at a dose of 2 to 3 g/kg/day beginning in the first 24 hours after birth.
4. Infants with a birth weight <1,500 g are provided with 2 to 3 g/kg/day shortly after birth. Infants >1,500 g are also initiated on 2 to 3 g/kg/day if indicated, depending on their size, clinical condition, and estimated time to achieve significant enteral volumes.
5. Protein infusion rates are increased to a target of 3.5 to 4 g/kg/day for premature infants and up to 3 g/kg/day for the term neonates.
F. Lipid. Currently, in the United States, soybean oil provides the fat source for IV fat emulsions.
1. The caloric value of 20% lipid emulsions is 2 kcal/mL (˜10 kcal/g). The use of 20% emulsions is preferred over 10% because the higher ratio of phospholipids to triglyceride in the 10% emulsion interferes with plasma triglyceride clearance. Twenty percent emulsions also provide a more concentrated source of calories. For these reasons, only 20% lipid emulsions are used.
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
