[Strategies for nutrition of the preterm infant with low and very low birth weight].

According to many experts in neonatal nutrition, the goal for nutrition of the preterm infant should be to achieve a postnatal growth rate approximating that of the normal fetus of the same gestational age. Unfortunately, most preterm infants, especially those born very preterm with extremely low birth weight, are not fed sufficient amounts of nutrients to produce normal fetal rates of growth and, as a result, end up growth-restricted during their hospital period after birth. Growth restriction is a significant problem, as numerous studies have shown definitively that undernutrition, especially of protein, at critical stages of development produces long-term short stature, organ growth failure, and both neuronal deficits of number and dendritic connections as well as later behavioral and cognitive outcomes. Glucose should be provided at 6-8 mg/min/kg as soon after birth as possible and adjusted according to frequent measurements of plasma glucose to achieve and maintain concentrations >45 mg/dl but <120 mg/dl to avoid the frequent problems of hyperglycemia and hypoglycemia. Similarly, lipid is required to provide at least 0.5 g/kg/day to prevent essential fatty acid deficiency. However, the high rate of carbohydrate and lipid supply that preterm infants often get, based on the incomplete assumption that this is necessary to promote protein growth, tends to produce increased fat in organs like the liver and heart as well as adipose tissue. More and better essential fatty acid nutrition is valuable, but more organ and adipose fat has no known benefit and many problems. Amino acids and protein are essential not only for body growth but for metabolic signaling, protein synthesis, and protein accretion. 3.5-4.0 g/kg/day are necessary to produce normal protein balance and growth in very preterm infants = Aggressive parenteral nutrition (PN) including amino acids is recommended for low-birthweight infants to prevent energy and protein deficit. PN can be provided as a standard, usually commercial, formulation, representing the average needs of a large group of patients. Alternatively, an individualized PN compound adapted to the patient's needs can be prescribed and prepared, usually on a daily basis. A combination of standardized PN bags, prepared under strict standardization criteria, for most neonates. Many preterm infants are too ill to receive substantial enteral feeds and require prolonged PN. It was reported that normal gastrointestinal structure and function are lost, villi become shorter, mucosal DNA is lost, Enteral feeding always is indicated and to date nearly all studies have shown that minimal enteral feeding approaches (e.g., 'trophic feeds') promote the capacity to feed enterally. Milk has distinct advantages over formulas in avoiding necrotizing enterocolitis (NEC). Breast milk is the preferred source of nutrients for newborn infants. The most common methods used are continuous milk infusion and intermittent (bolus) milk delivery (usually every 3 h). Feeding promotes more "normal" feed-fasting and marked differences are observed in feeding tolerance and growth between continuous vs. bolus tube-feeding methods. Continuous feeding is associated with more significant feeding intolerance.