Effect of Low versus High Intravenous Amino Acid Intake on Very Low Birth Weight Infants in the Early Neonatal Period

Abstract

Greater protein intakes are required than have been commonly used to achieve fetal in utero protein accretion rates in preterm neonates. To study the efficacy and safety of more aggressive amino acid intake, we performed a prospective randomized study in 28 infants [mean wt, 946 Ϯ 40 g (SEM)] of 1 (low amino acid intake, LAA) versus 3 g·kg Ϫ1 ·d Ϫ1 (high amino acid intake, HAA) at 52.0 Ϯ 3.0 h of life. After a minimum of 12 h of parenteral nutrition, efficacy was determined by protein balance and was significantly lower in the LAA versus HAA groups by both nitrogen balance (Ϫ0. Abbreviations PN, parenteral nutrition LAA, low amino acid intake HAA, high amino acid intake Int leuc , leucine intake rate Q leuc , leucine flux rate Ox leuc , leucine oxidation rate NOD leuc , nonoxidative leucine disposal intake rate RP leuc , rate of leucine appearance from protein breakdown ELBW, extremely low birth weight BUN, blood urea nitrogen GCMS, gas chromatography-mass spectroscopyThe current standard for postnatal nutrition in all preterm infants is one that duplicates normal in utero fetal growth rates (1). Owing to advances in perinatal care, more very preterm infants are surviving. These infants have unique nutritional metabolic requirements for growth, predicted by low energy stores, high protein flux rate, and a high metabolic rate as a result of a relatively larger mass of metabolically active organs. Nevertheless, it is common practice in many neonatal intensive care units to limit nutrient administration, particularly amino acids, to ELBW or sick neonates in the early neonatal period because of concerns of substrate intolerance. Several studies suggest that this delay in nutrition results in postnatal malnutrition that produces measurable growth failure at hospital discharge (2-4).Although strategies to improve growth necessitate delivery of larger amounts of both energy and protein beginning shortly after birth, there are reasons to suggest that focusing on protein delivery may be particularly important. Throughout life, maximal weight-specific protein gain occurs before 32 wk gestation (5). Data from studies in fetal animal models suggest that amino acid metabolic rates may be a much more sensitive indicator than growth rate of adequate nutrition before term (6). Additionally, recent data suggest that long-term developmental outcome in the preterm may be correlated with early protein intake (7

Stopping Parenteral Nutrition for 3 Hours Reduces False Positives in Newborn Screening

“…[10][11][12] None of the studies with early AAs administration up to 2.3 g/kg/d reported metabolic acidosis or clinically significant hyperaminoacidemia. 16 Also, the plasma concentrations of all essential AAs and most nonessential AAs increased with early AA administration and were more in concordance with reference ranges from healthy fetuses or breast fed infants. 16 In addition, early parenteral AA intake is associated with a reduction in insulin-treated hyperglycemia 17 and better long-term neurodevelopmental outcomes.…”

“…16 Also, the plasma concentrations of all essential AAs and most nonessential AAs increased with early AA administration and were more in concordance with reference ranges from healthy fetuses or breast fed infants. 16 In addition, early parenteral AA intake is associated with a reduction in insulin-treated hyperglycemia 17 and better long-term neurodevelopmental outcomes. 18 Thus, early PN containing AA supplementation in 24 hours of life has become part of the standard care for VLBW infants.…”

Feeding Very-Low-Birth-Weight Infants: Our Aspirations versus the Reality in Practice

“…The preterm infant should have the capacity to metabolize the same amount of amino acids as its postconceptionally age-matched intrauterine counterpart, although the preterm infant misses the maternal metabolic clearance possibility its fetal counterpart has. However, it has been shown that early administration of intravenous amino acids is safe and brings the preterm newborn in an anabolic state [13,14,15]. We have studied immediate and 2-year follow-ups from our own cohort, where we infused 2.4 g of amino acids per kilogram BW per day from birth onwards, compared to a stepwise increment in 2–3 days.…”

The Effects of Early Parenteral Amino Acids on Sick Premature Infants

“…[1][2][3][4][5][6][7][20][21][22]. A recent study reported that early administration of amino-acid improved preterm infant weight with less number of infants below the tenth percentile in the growth curve, but there was a slightly higher incidence of bronchopulmonary dysplasia.…”