Ekhard E. Ziegler
3
Nourishing Preterm and Low-Birth-Weight Infants
Provision of nutrients has to overcome the im- maturity of the intestinal tract; this is the most important physiological limitation in these in- fants. This necessitates the use of parenteral nu- trition during the early days and often weeks of life. Although parenteral nutrition carries risks, especially that of infection, failure to provide nu- trients parenterally would place these infants at high risk of impaired neurodevelopment or im- paired host defenses. Immaturity of the intestinal tract is also the main reason why preterm infants are susceptible to necrotizing enterocolitis (NEC). While nutrients are provided parenter- ally, small trophic feedings (gastrointestinal priming) are given with the sole purpose of stim- ulating the intestinal tract to undergo matura- tion. Breast milk is the most effective and safest feed to bring about intestinal maturation. Once maturation has occurred, nutrients can be deliv- ered enterally and parenteral nutrition may be phased out.
Nutritional support of preterm infants oc- curs in four distinct phases, each with its own risks and challenges. During the early phase, nutrients are almost exclusively provided via the parenteral route, while small enteral feedings (gastrointestinal priming) are used to prod the immature intestinal tract into undergoing mat- uration. During the subsequent transition phase, enteral feeding is slowly advanced as the intestinal tract shows evidence of maturation, and parenteral nutrition is gradually phased out. During the late phase, infants are on exclu- sive enteral feeding and are expected to grow normally. If provided the necessary nutrients, preterm infants may also show catch-up growth, that is, they may be making up for lost time dur- ing the early phase. Preterm infants continue to have special nutritional needs after discharge from hospital.
Early Phase
During the immediate postnatal period, the ob- jective of nutritional support is twofold: to pro- vide an uninterrupted flow of nutrients so that the anabolic state that existed in utero can continue with minimal or no interruption, and to stimulate the immature gastrointestinal tract to undergo maturation. As gastrointestinal maturation pro- gresses, a gradual shift occurs from exclusive par- enteral nutrition to predominant, and finally ex- clusive, enteral nutrition. The early phase ends when enteral feedings exceed about 20 ml/kg/day.
Parenteral Nutrition
In immature infants, parenteral nutrition must be- gin immediately (within 2 h of birth), and as a min- imum must provide glucose, amino acids, electro- lytes, Ca, P and Mg (starter parenteral nutrition) until full parenteral nutrition can be started. It is acceptable for the amount of amino acid to be less than 3.5 g/kg/day for a few days. Initiation of lipid emulsion is somewhat less urgent, and a delay of 24 h is acceptable. The initial rate should be 1.0 g lip- ids/kg/day. The efficacy and safety of parenteral nutrition starting immediately after birth have been established [3] . Full parenteral nutrition should be maintained until enteral feedings of 20 ml/kg/day are regularly tolerated. As the feedings are increased, the amount of parenteral nutrition is tapered, with total (parenteral plus enteral) in- take of nutrients always remaining at full level.
Enteral Nutrition
The anatomically and functionally immature in- testine can undergo maturation in a relatively short time if the necessary stimulation is provided in the form of trophic feedings (gastrointestinal priming). Gastrointestinal priming should be started on the first day of life. Feeding volumes initially may be as low as 2 ml every 6 or 4 h. Stim- ulation of the gut is initially the sole objective of enteral feeding. Motility serves as a marker of gut maturation and is monitored clinically by assess- ment of gastric residuals. As gastric emptying im-
216 Ziegler
proves, it is assumed that the ability to digest and absorb nutrients is also improving. Gastric emp- tying thus serves as an important clinical guide in early enteral feeding. The risk of NEC is quite low with trophic feedings, but it somewhat increases subsequently as feeding volumes increase.
The preferred feed for gastrointestinal prim- ing is maternal milk or, if not available, donor milk. Donor milk is pasteurized and free of vi- ruses such as HIV and cytomegalovirus. Al- though pasteurization diminishes some of the protective and trophic factors of human milk, do- nor milk retains its protective effect against NEC [4] and sepsis and has strong trophic effects.
When human milk is not available, formulas can also be used for gastrointestinal priming.
Transition Phase
Feeding volumes are usually kept low for several days and are gradually increased as gastric residu- als diminish. At each new level, the adequacy of gastric emptying (absence of gastric residuals) must be ascertained before the feeding volume is further increased. The presence of gastric residu- als does not require cessation of feedings as long as there are no signs suggestive of NEC. The use of gastrointestinal priming has been shown to lead to earlier establishment of full feedings and to earlier hospital discharge without an increase in NEC [5] . In fact, earlier achievement of full feedings has been shown to decrease the risk of sepsis [6] . Feeding volumes can be increased by 20 ml/kg each day as gastric residuals permit. Al-
though more rapid increases are safe, intestinal maturation requires time and therefore more rap- id increases are not necessary. When feeding vol- umes are 80–100 ml/kg/day, fortification of breast milk is usually initiated, although in some units fortification is started much earlier. Parenteral nutrition can be discontinued when enteral feed- ings are at least 90% of the full amount.
Late Phase
The late phase begins when full feedings are es- tablished and parenteral nutrition is discontin- ued. The objective of nutrition is to allow growth to proceed parallel to intrauterine growth. The energy and protein intakes listed in table 1 are needed to support growth at the intrauterine rate.
If the infant is to catch up in growth, intakes must be increased by perhaps 10–20%. Intakes below those listed in table 1 lead to extrauterine growth failure with all its negative consequences. Feed- ings are fortified human milk or, when not avail- able, special formulas.
With standard preterm formulas with a pro- tein/energy ratio (3.0 g/100 kcal) protein intakes are marginally adequate. Formulas with higher protein content (3.3–3.6 g/100 kcal) are therefore preferable in order to achieve appropriate ‘catch up’ growth of lean body mass.
Breast milk must be fortified (supplemented) with nutrients in order to meet the preterm in- fant’s high needs ( table 1 ). Fortifiers are available as powders and as liquids. Commercially available fortifiers provide the necessary nutrients in suffi-
Table 1. Requirements for protein and energy (best estimates by factorial and empirical methods) Body weight
500–1,000 g 1,000–1,500 g 1,500–2,200 g 2,200–3,000 g
Fetal weight gain, g/kg/day 19.0 17.4 16.4 13.4
Protein, g/kg/day 4.0 3.9 3.7 3.4
Energy, kcal/kg/day 106 115 123 130
Protein/energy, g/100 kcal 3.8 3.4 3.0 2.6
Koletzko B, et al. (eds): Pediatric Nutrition in Practice. World Rev Nutr Diet. Basel, Karger, 2015, vol 113, pp 214–217 DOI: 10.1159/000360342
3
cient amounts with the exception of protein, which is inadequate in most fortifiers. Protein intakes are therefore often inadequate. The reason why pow- der fortifiers, and some liquid fortifiers, are too low in protein is that they were designed at a time when the overriding consideration was the avoid- ance of ‘high’ protein intakes in the face of variable protein concentrations of expressed human milk.
The inevitable consequence is that protein intakes are too low most of the time. Today the ill effects of inadequate protein intakes are better known.
Fortifiers (liquid) with higher protein content are available and should be used. With their use, pro- tein intakes are adequate most of the time, albeit being somewhat high at times when the protein content of expressed milk is relatively high.
Customizing approaches to fortification have been developed with the aim of overcoming the
inadequacy of protein intakes with powder forti- fiers. A method for BUN-guided fortification has been described by Arslanoglu et al. [7] . The meth- od is somewhat cumbersome, which may be the reason for its limited use. Approaches based on periodic analysis of expressed milk (targeted for- tification) also have been shown to lead to more adequate nutrient intakes and improved growth [8] .
After Discharge
When preterm infants leave the hospital their nu- trient needs are still high. In addition, they often have accrued deficits in bone mineral content.
This is the reason why there is a need for contin- ued fortification of human milk. In the case of formula feeding, the use of enriched post-dis- charge formulas is necessary.
7 Arslanoglu S, Moro GE, Ziegler EE: Ad- justable fortification of human milk fed to preterm infants: does it make a differ- ence? J Perinatol 2006; 26; 1–8.
8 Polberger S, Rọihọ NCR, Juvonen P, Moro GE, Minoli I, Warm A: Individual- ized protein fortification of human milk for preterm infants: comparison of ul- trafiltrated human milk protein and a bovine whey fortifier. J Pediat Gast Nut 1999; 29: 332–338.
References
1 Ehrenkranz RA, Dusick AM, Vohr BR, Wright LL, Wrage LA, Poole WK:
Growth in the neonatal intensive care unit influences neurodevelopmental and growth outcomes of extremely low birth weight infants. Pediatrics 2006; 117:
1253–1261.
2 Ziegler EE: Meeting the nutritional needs of the low-birth-weight infant.
Ann Nutr Metab 2011; 58(suppl 1):8–18.
3 te Braake FWJ, van den Akker CHP, Wattimena DJL, Huijmans JGM, van Goudoever JB: Amino acid administra- tion to premature infants directly after birth. J Pediatr 2005; 147: 457–461.
4 Boyd CA, Quigley MA, Brocklehurst P:
Donor breast milk versus infant formula for preterm infants: systematic review and meta-analysis. Arch Dis Child Fetal Neon Ed 2007; 92:F169–F175.
5 Tyson JA, Kennedy KA: Trophic feed- ings for parenterally fed infants (Re- view). Cochrane Database Syst Rev 2005;CD000504.
6 Ronnestad A, Abrahamsen TG, Medbứ S, Reigstad H, Lossius K, Kaaresen PI, et al: Late-onset septicemia in a Norwegian national cohort of extremely premature infants receiving very early full human milk feeding. Pediatrics 2005; 115:e269–
e276.
3 Nutritional Challenges in Special Conditions and Diseases
Key Words
Diet ã Type 1 diabetes ã Glycemic index ã Intensive insulin therapy ã Carbohydrate counting
Key Messages
• Nutrition management is one of the fundamental elements of care and education for children with type 1 diabetes
• Medical nutrition therapy should be provided at di- agnosis of diabetes and reviewed at least annually to increase dietary knowledge and adherence • Healthy eating recommendations suitable for all
children should underlie all education. Education on carbohydrate counting should be given with consideration of dietary quality and low-glycemic index food choices
• Matching of the insulin dose to carbohydrate intake is recommended for children using intensive insu- lin therapy. Carbohydrate counting has the poten- tial to increase flexibility in food intake and quality of life. However, regularity in meal routines remains important for optimal metabolic outcomes • There is increasing evidence that other macronutri-
ents impact postprandial blood glucose levels. Re- cent studies have shown that it is important to con- sider both protein and fat in the calculation of the meal insulin dose and how it is delivered
© 2015 S. Karger AG, Basel
Introduction
Type 1 diabetes mellitus (T1DM) is one of the most common chronic diseases in childhood [1] . Nutritional management is fundamental to dia- betes care and education. Nutrition therapy should focus on interventions to ensure normal growth and development, promote lifelong healthy eating habits and optimize glycemic con- trol as well as assist with prevention of the com- plications associated with diabetes.
Dietary recommendations for children with diabetes are based on healthy eating recommen- dations suitable for all children – and thus the entire family [2] . Nutrition education should be individualized and adapted to cultural, ethnic, religious and family traditions. Regular dietetic assessment is necessary to adapt nutritional ad- vice to growth, diabetes management and life- style changes as well as to permit the identifica- tion and treatment of disordered eating patterns.
Eating disorders and celiac disease occur more commonly in T1DM and require specialized di- etetic support. All children with diabetes and their families should have access to a specialist pediatric dietitian with experience in childhood diabetes as part of the interdisciplinary diabetes
Koletzko B, et al. (eds): Pediatric Nutrition in Practice. World Rev Nutr Diet. Basel, Karger, 2015, vol 113, pp 218–225 DOI: 10.1159/000367863