Parenteral amino acid and energy administration to premature infants in early life

After birth, the nutritional supply through the umbilical cord ceases. Premature infants do not immediately tolerate full enteral feedings, yet they retain high nutritional needs for both growth and metabolic maintenance. Parenteral nutrition should therefore be initiated as quickly as possible after premature birth, thereby reducing the dependence on endogenous substrates. Intrauterine studies show very high amino acid uptake, clearly exceeding accretion rates. Studies covering the early neonatal period demonstrate that the initiation of high-dose amino acid administration directly after birth is safe and effective, even at low energy intakes. Future research should reveal whether usage could be improved through better amino acid solutions or by providing more energy via lipids from birth onwards as well.     

Effect of two amino acid solutions on leucine turnover in preterm infants

OBJECTIVE: To assess the effect of two different parenteral amino acid mixtures, Trophamine and Primene, on leucine turnover in preterm infants. METHOD: Leucine kinetics were measured with [5,5,5 D3]leucine tracer in 15 infants receiving Trophamine (group 'T') (mean birth weight 1,263 g) and 22 who received Primene (group 'P') (mean birth weight 1,336 g) during two study periods, within a few hours after birth but before introduction of parenteral amino acid solution, and again at postnatal day 7. The rate of appearance of leucine was calculated from the enrichment of alpha-ketoisocaproic acid in plasma. RESULTS: There were no significant differences in leucine turnover within a few hours after birth in the two groups. In the infants who received Primene leucine turnover on day 7 was significantly lower than in those who received Trophamine (269 +/- 43 vs. 335 +/- 27, p < 0.05). Despite a higher intake of leucine in the Trophamine group (108 +/- 10 vs. 77 +/- 8 micromol.kg(-1).h(-1)), leucine released from proteins at day 7 was higher in this group compared to Primene (227 +/- 27 vs. 192 +/- 42 micromol.kg(-1).h(-1)). CONCLUSIONS: Primene administration results in lower leucine released from proteins, an estimate of protein breakdown, than Trophamine in preterm infants. Increases in whole body leucine turnover in response to administration of i.v. amino acids is influenced by the composition of the amino acid mixture. The factors responsible for this difference remain to be elucidated.     

A controlled trial of glucose versus glucose and amino acids in premature infants.

A controlled study comparing two intravenous fluid regimens was performed in sick, premature infants. The regimens were isocaloric at 60 calories/kg/day, one providing glucose alone, the other glucose plus 2.5 gm/kg of amino acids. There was no difference in changes in body weight between the two groups; infants receiving glucose alone were in negative nitrogen balance; those receiving glucose plus amino acids were in positive nitrogen balance. Plasma amino acid values were compared to published, postprandial normal values. The TEAA and TAA of infants receiving amino acids were not different from normal. Values of TEAA and TAA of infants receiving glucose alone were significantly lower. Essential fatty acid deficiency developed in infants receiving amino acids but not in those receiving glucose alone. It is concluded that the glucose plus amino acid regimen results in anabolism without undue metabolic costs.     

早产儿黄疸早期干预的临床观察

目的 探讨早期干预早产儿黄疸的疗效和对肠外营养及体质量增长的影响.方法 174例早产儿,出生体质量1500～2000 g者(A组)87例,出生体质量＜1500 g者(B组)87例,分别按常规干预和早期干预分组.常规组血清总胆红素(TSB)达干预推荐方案的标准时光疗,早期组于出现黄疸,但TSB未达干预标准即光疗.结果 A、B组的早期组胆红素峰值(PSB)均低于常规组[A组:(209.48±38.99)μmol/L和(266.59±37.11)μmol/L,B组:(180.23±31.63)μmol/L和(243.68±37.45)μmol/L,P均＜0.05];早期组与常规组相比黄疸消退日龄早[A组:(14.5±4.4)d和(18.0±3.8)d,B组:(10.8±3.0)d和(18.8±5.5)d,P均＜0.05],脂肪乳起始日龄早[A组:(5.8±2.7)d和(8.1±3.7)d,P＞0.05;B组:(3.8±1.8)d和(9.2±4.4)d,P＜0.05],恢复出生体质量日龄早[A组:(13.1±6.0)d和(14.4±4.0)d,P＞0.05;B组:(9.3±4.8)d和(15.4±5.6)d,P＜0.05].结论 早期干预可以使早产儿尤其是极低出生体重儿PSB降低,黄疸持续时间缩短,利于早期添加脂肪乳和早产儿体质量增长.     

早产儿黄疸早期干预的临床观察

目的探讨早期干预早产儿黄疸的疗效和对肠外营养及体质量增长的影响。方法174例早产儿，出生体质量1500～2000g者（A组）87例，出生体质量〈1500g者（B组）87例，分别按常规干预和早期干预分组。常规组血清总胆红素（TSB）达干预推荐方案的标准时光疗，早期组于出现黄疸，但TSB未达干预标准即光疗。结果A、B组的早期组胆红素峰值（PSB）均低于常规组[A组：（209．48±38．99）umol／L和（266．59±37．11）umol／L，B组：（180．23±31．63）umol／L和（243．68±37．45）umol／L，P均〈0．05]；早期组与常规组相比黄疸消退日龄早[A组：（14．5±4．4）d和（18．0±3．8）d，B组：（10．8±3．0）d和（18．8±5．5）d，P均〈0．05l，脂肪乳起始日龄早fA组：（5．8±2．7）d和（8．1±3．7）d，P〉0．05；B组：（3．8±1．8）d和（9．2±4．4）d，P〈0．05]，恢复出生体质量日龄早[A组：（13．1±6．0）d和（14．4±4．0）d，P〉0．05；B组：（9．3±4．8）d和（15．4±5．6）d，P〈0．05]。结论早期干预可以使早产儿尤其是极低出生体重儿PSB降低，黄疸持续时间缩短，利于早期添加脂肪乳和早产儿体质量增长。     

Increased parenteral amino acid administration to extremely low-birth-weight infants during early postnatal life

BACKGROUND: Early administration of parenteral amino acids to infants with extremely low birth weight (birth weight < or = 1,000 g) has been encouraged to foster growth. However, excessive intravenous intake of amino acids may cause metabolic acidosis and uremia in extremely low birth weight infants. The hypothesis for this study was that extremely low birth weight infants would tolerate slightly increased early postnatal parenteral amino acid administration and benefit. METHODS: The peak daily parenteral amino acid dosage was increased from 3 g/kg (standard group) to 4 g/kg (modified group). The corrected parenteral amino acid dosage was computed to account for enteral protein intake and keep the combined daily intravenous amino acid and enteral protein intake at or below 3 g . kg -1 . d -1 in the standard group and 4 g . kg -1 . d -1 in the modified group. The primary outcome measure was plasma bicarbonate concentration as an indicator of acid-base status. Data were collected for patient demographics, nutritional intake, serum bicarbonate and serum urea nitrogen concentrations, and outcome. RESULTS: The corrected parenteral amino acid intake of the modified group was 16% greater at postnatal week 1 (3.30 +/- 0.83 g . kg -1 . d -1; mean, +/-1 SD) and 18% greater (3.86 +/- 0.94 g . kg -1 . d -1 ) at postnatal week 2 than the parenteral amino acid intake of the standard group. In the modified group, the mean serum bicarbonate concentration was 19.1 +/- 1.8 mEq/dL at week 1 and 23.9 +/- 2.9 mEq/dL at week 2, with no difference between the groups. At week 1, serum urea nitrogen concentrations were the same in both groups. The mean serum urea nitrogen concentration of the modified group at postnatal week 2 (18.2 +/- 8.8 mg/dL) was unchanged from postnatal week 1, but was greater than that of the standard group at postnatal week 2. Weight gain was the same in both groups. Corrected parenteral amino acid intake at postnatal week 1 correlated directly with weight gain from birth to postnatal week 2 ( P < 0.03) in both groups. CONCLUSIONS: Infants with extremely low birth weight tolerated parenteral amino acid intake of approximately 4 g . kg -1 . d -1. Mild increases of mean serum urea nitrogen concentration and mean weight gain were associated with increased parenteral amino acid administration without significant acidosis.     

Amino acid administration to premature infants directly after birth

OBJECTIVES: To test the hypothesis that the administration of 2.4 g amino acids (AA)/(kg.d) to very low birth weight infants is safe and results in a positive nitrogen balance. STUDY DESIGN: We conducted a randomized, clinical trial. Preterm infants with birth weights <1500 g received either glucose and 2.4 g AA/(kg.d) from birth onward (n=66) or solely glucose during the first day with a stepwise increase in AA intake to 2.4 g AA/(kg.d) on day 3 (n=69). Blood gas analysis was performed daily during the first 6 postnatal days; blood urea nitrogen levels were determined on days 2, 4, and 6; AA plasma concentrations and nitrogen balances were determined on days 2 and 4. Student t tests, Mann-Whitney tests, and chi2 tests were performed to compare groups. RESULTS: Infants supplemented with AA had no major adverse side effects. Their blood urea nitrogen levels were higher, nitrogen balance turned positive upon AA administration, and more AA concentrations were within reference ranges. CONCLUSIONS: High-dose AA administration to very low birth weight infants can be introduced safely from birth onward and results in an anabolic state.     

Stable glucose balance in premature infants with fluid restriction and early enteral feeding

Hyperglycemia readily develops during intravenous glucose administration in premature infants. In this study glucose homeostasis was measured in 24 infants appropriate-for-gestational age with a gestational age between 27 and 34 weeks and a birthweight between 1,150 and 2,610 g. The infants were randomly assigned to one of two treatment groups. Fluid intake consisted of intravenous infusion of 5% glucose in Group 1 and 10% glucose in Group 2, and increasing amounts of human milk from the first day of life. The infants were treated in incubators with high air humidity in order to minimize insensible water loss and total fluid intake was restricted. The fluid restriction and early enteral feeding decreased the total amount of glucose given parenterally and thereby the risk of hyperglycemia. Glucose homeostasis was efficiently maintained in both groups and under the conditions described hydration by intravenous infusion of 5% and 10% glucose appear equally well tolerated.     

Supplementary parenteral nutrition in premature infants. Adaptation to amino acid intake

The authors report a controlled study of the use of 2 types of amino-acid solutions for premature infants nutrition in the first days of life, one of the solution (solution I) being adapted for prematures. The average amino-acid blood levels in prematures receiving solution I were close to those observed in cord blood; Plasma taurine, alanine and arginine concentrations were significantly lower with normalized levels of aromatic amino-acids, lysine, taurine and proline; serum ammonia level was also lower. This study shows that using an amino-acid solution adapted to prematures as a supplement to parenteral nutrition during the first days of life allows to progressively increase the nitrogen intakes without inducing dangerous plasma levels of some amino-acids.     

Blood glucose and plasma amino acid concentrations in infants of diabetic mothers.

Postnatal blood glucose and individual plasma free amino acid levels were measured in 14 newborn infants of diabetic mothers. All infants had a significantly lower blood glucose concentration than normal controls but no significant correlation was observed between the blood glucose values and any of the amino acids determined. As regards the quantitative and qualitative changes of the plasma aminogram, the total concentration of amino acids and the level of a few individual amino acids (glycine, alanine, taurine, and valine) were significantly elevated in full-term babies. However, no significant difference was found in the total plasma concentration of amino acids between premature infants of diabetic mothers and premature control infants, but the plasma alanine level was higher in the former. It is of interest that total plasma amino acid, alanine, and glycine levels were elevated in the asphyxiated babies. This suggests that the postnatal hyperaminoacidemia observed in infants of diabetic mothers was due to birth asphyxia rather than to impaired gluconeogenesis. The possible role of a defective gluconeogenesis in the etiology of postnatal hypoglycemia in infants of diabetic mothers is not supported by these data.