Pediatric parenteral amino acid mixture in low birth weight infants

A mixture of amino acids designed to maintain normal plasma amino acid concentrations in infants and children requiring parenteral nutrition was evaluated in 28 low birth weight (LBW) infants (birth weight, 750 to 1750 g; postnatal age, 1 to 4 weeks) who required parenteral nutrients for optimal nutritional management. Sixteen babies received only parenteral nutrients for five to 21 days. Ten of these received a typical regimen by peripheral vein (1.91 +/- 0.16 g/kg/d of amino acids and 44.7 +/- 4.4 kcal/kg/d) and six received a typical regimen through a central vein (2.39 +/- 0.11 g/kg/d of amino acids and 95.9 +/- 14.5 kcal/kg/d). Mean weight gain of the peripheral vein subgroup was 10.3 +/- 10.6 g/kg/d; mean nitrogen balance was 230 +/- 66 mg/kg/d. Both the mean rate of weight gain (17.2 +/- 5.1 g/kg/d) and the mean rate of nitrogen retention (267 +/- 49 g/kg/d) of the central vein subgroup were similar to intrauterine rates. In these two subgroups as well as the total population, plasma concentrations of all amino acids except phenylalanine were within the 95% confidence limits of the plasma concentrations observed in LBW infants fed sufficient amounts of human milk to result in a rate of weight gain similar to the intrauterine rate. However, although plasma tyrosine and cyst(e)ine concentrations were within the 95% confidence limits of the plasma concentrations goals, the LBW infant's ability to use N-acetyl-L-tyrosine and cysteine HCl appears to be even less than that of the term infant and older child. In toto, these data support the efficacy of the amino acid mixture evaluated for LBW infants. Of equal importance, they suggest that the LBW infant's ability to use parenterally delivered amino acids is not as limited as commonly thought.     

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.     

Effect of low versus high intravenous amino acid intake on very low birth weight infants in the early neonatal period

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 +/- 40 g (SEM)] of 1 (low amino acid intake, LAA) versus 3 g.kg(-1).d(-1) (high amino acid intake, HAA) at 52.0 +/- 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 (-0.26 +/- 0.11 versus 1.16 +/- 0.15 g.kg(-1).d(-1), p < 0.00005) and leucine stable isotope (0.184 +/- 0.17 versus 1.63 +/- 0.20 g.kg(-1).d(-1), p < 0.0005) methods. Leucine flux and oxidation and nonoxidative leucine disposal rates were all significantly higher in the HAA versus LAA groups (249 +/- 13 versus 164 +/- 8, 69 +/- 5 versus 32 +/- 3, and 180 +/- 10 versus 132 +/- 8 micro mol.kg(-1).h(-1), respectively, p < 0.005), but leucine appearance from protein breakdown was not (140 +/- 15 in HAA versus 128 +/- 8 micro mol.kg(-1).h(-1)). In terms of possible toxicity with HAA, there were no significant differences between groups in the amount of sodium bicarbonate administered, degree of acidosis as determined by base deficit, or blood urea nitrogen concentration. Parenteral HAA versus LAA intake resulted in increased protein accretion, primarily by increasing protein synthesis versus suppressing protein breakdown, and appeared to be well tolerated by very preterm infants in the first days of life.     

积极肠外营养支持方案在胎龄<34周早产儿中的应用

目的 探讨积极肠外营养支持方案(高初始剂量氨基酸和脂肪乳)在胎龄<34周早产儿肠外营养中的近期疗效及耐受情况.方法 根据早期应用氨基酸和脂肪乳剂量不同,将2019年5月至2019年12月收治,生后24小时内入院、胎龄<34周138例早产儿随机分2组.积极肠外营养组69例,氨基酸自2.5 g/(kg·d)始,逐日增加1....     

Amino acids, glutamine, and protein metabolism in very low birth weight infants

Glutamine has been proposed to be conditionally essential for premature infants, and the currently used parenteral nutrient mixtures do not contain glutamine. De novo glutamine synthesis (DGln) is linked to inflow of carbon into and out of the tricarboxylic acid (TCA) cycle. We hypothesized that a higher supply of parenteral amino acids by increasing the influx of amino acid carbon into the TCA cycle will enhance the rate of DGln. Very low birth weight infants were randomized to receive parenteral amino acids either 1.5 g/kg/d for 20 h followed by 3.0 g/kg/d for 5 h (AA1.5) or 3.0 g/kg/d for 20 h followed by 1.5 g/kg/d for 5 h (AA3.0). A third group of babies received amino acids 1.5 g/kg/d for 20 h followed by 3.0 g/kg/d for 20 h (AA-Ext). Glutamine and protein/nitrogen kinetics were examined using [5-(15)N]glutamine, [2H5]phenylalanine, [1-(13)C,15N]leucine, and [15N2]urea tracers. An acute increase in parenteral amino acid infusion for 5 h (AA1.5) resulted in decrease in rate of appearance (Ra) of phenylalanine and urea, but had no effect on glutamine Ra. Infusion of amino acids at 3.0 g/kg/d for 20 h resulted in increase in DGln, leucine transamination, and urea synthesis, but had no effect on Ra phenylalanine (AA-Ext). These data show an acute increase in parenteral amino acid-suppressed proteolysis, however, such an effect was not seen when amino acids were infused for 20 h and resulted in an increase in glutamine synthesis.     

Amino acid mixture designed to maintain normal plasma amino acid patterns in infants and children requiring parenteral nutrition

A mixture of amino acids designed to maintain normal plasma amino acid concentrations of infants and children requiring parenteral nutrition was evaluated in 40 infants and children receiving only parenteral nutrients (2.39 +/- 0.26 g/kg/d of amino acids and 110.3 +/- 10.4 kcal/kg/d) for five to 21 days. The children ranged in weight from 2.0 to 12.6 kg (median weight, 3.83 kg; fifth to 95th percentile, 2.06 to 11.1 kg) and in age from 1 week to 43.6 months (median age, 2.7 months; fifth to 95th percentile, 0.2 to 25.3 months). Mean weight gain was 11.0 +/- 5.0 g/kg/d; mean nitrogen balance was 242 +/- 70 mg/kg/d. Plasma concentrations of all amino acids except tyrosine were within the normal range (ie, within the 95% confidence limits of the two-hour postprandial plasma concentrations observed in 30-day-old, healthy, normally growing, breast-fed, term infants) throughout the period of study. Mean prestudy and poststudy serum total protein, albumin, and transthyretin (prealbumin) concentrations were not significantly different. However, plasma transthyretin concentration increased in all children with low prestudy concentrations. Mean poststudy serum total bilirubin concentration of the total population was not different from the mean prestudy concentration. This was true also for the 31 children who received the parenteral amino acid mixture for more than ten days. In contrast to the expected 30% to 50% incidence of cholestasis, only one of these 31 experienced an unexplained increase in serum total bilirubin concentration during study, suggesting that normalizing plasma amino acid concentrations and/or providing taurine during parenteral nutrition may decrease the incidence of cholestasis associated with this therapy.     

A modified vitamin regimen for vitamin B2, A, and E administration in very-low-birth-weight infants

INTRODUCTION: Very-low-birth-weight (VLBW; birth weight, <1,500 g) infants receive preterm infant formulas and parenteral multivitamin preparations that provide more riboflavin (vitamin B2) than does human milk and more than that recommended by the American Society of Clinical Nutrition. VLBW infants who are not breast-fed may have plasma riboflavin concentrations up to 50 times higher than those in cord blood. The authors examined a vitamin regimen designed to reduce daily riboflavin intake, with the hypothesis that this new regimen would result in lower plasma riboflavin concentrations while maintaining lipid-soluble vitamin levels. METHODS: Preterm infants with birth weight < or =1,000 g received either standard preterm infant nutrition providing 0.42 to 0.75 mg riboflavin/kg/day (standard group), or a modified regimen providing 0.19 to 0.35 mg/kg/day (modified group). The modified group parenteral vitamin infusion was premixed in Intralipid. Enteral feedings were selected to meet daily riboflavin administration guidelines. Plasma riboflavin, vitamin A, and vitamin E concentrations were measured weekly by high-performance liquid chromatography. Data were analyzed with the independent t test, chi, and analysis of variance. RESULTS: The 36 infants (17 standard group, 19 modified group) had birth weight and gestational age of 779 +/- 29 g and 25.5 +/- 0.3 weeks (mean +/- SEM) with no differences between groups. Modified group infants received 38% less riboflavin (0.281 +/- 0.009 mg/kg/day), 35% more vitamin A (318.3 +/- 11.4 microg/kg/day), and 14% more vitamin E (3.17 +/- 0.14 mg/kg/day) than standard group infants. Plasma riboflavin rose from baseline in both groups but was 37% lower in the modified group during the first postnatal month (133.3 +/- 9.9 ng/mL). Riboflavin intake and plasma riboflavin concentrations were directly correlated. Plasma vitamin A (0.222 +/- 0.022 microg/mL) and vitamin E (22.26 +/- 1.61 /mL) concentrations were greater in the modified group. CONCLUSIONS: The modified vitamin regimen resulted in reduced riboflavin intake and plasma riboflavin concentration, suggesting plasma riboflavin concentration is partially dose dependent during the first postnatal month in VLBW infants. Modified group plasma vitamin A and vitamin E concentrations were greater during the first month, possibly because the vitamins were premixed with parenteral lipid emulsion. Because of the complexity of this protocol, the authors suggest that a parenteral multivitamin product designed for VLBW infants which uses weight-based dosing should be developed.     

Persistently low blood retinol levels during and after parenteral feeding of very low birth weight infants: examination of losses into intravenous administration sets and a method of prevention by addition to a lipid emulsion

Very low birth weight infants have little storage of hepatic retinol and are, therefore, highly dependent upon an exogenous supply. The recent association between low serum retinol level and bronchopulmonary dysplasia and the persistently low serum levels of retinol during total parenteral nutrition prompted a prospective study to evaluate serial changes in serum retinol levels during 1 month of total parenteral nutrition (retinol dose 455 micrograms/d) and again during 1 month of total enteral feeding (retinol dose 200 to 300 micrograms/d) in the same infants. Infants were divided into two groups. Group 1 consisted of infants weighing less than 1,000 g (n = 24) and group 2 consisted of infants weighing 1,000 to 1,500 g (n = 17). Although initial mean levels of retinol were similar in both groups (14.8 +/- 0.9 and 13.5 +/- 0.7 micrograms/dL), there was wide variation between infants. In group 1 infants, there was a significant (P less than .01) decline in retinol level by the second week of life (to 9.2 +/- 1 micrograms/dL), which persisted during total parenteral nutrition, but increased to 13.4 +/- 2 after 1 week of enteral feeding. This level was maintained throughout enteral feeding. In group 2 infants, there was no significant change in serum retinol level throughout the study. During total parenteral nutrition, several infants had retinol levels below 10 micrograms/dL, a level associated with signs of retinol deficiency in older children. Because losses of retinol are known to occur in smaller volume total parenteral nutrition solutions, it was speculated that losses of retinol in our patients were due to retinol losses in the total parenteral nutrition delivery system.(ABSTRACT TRUNCATED AT 250 WORDS)     

早期输注大剂量氨基酸对改善早产儿氮平衡的有效性研究

目的评价早期输注大剂量氨基酸对改善早产儿氮平衡的有效性。方法将2010年1月—2010年12月间出生24 h内体质量1 000～2 000 g入住新生儿重症监护室(NICU)接受肠道外营养治疗的早产儿,随机分为两组。实验组于生后24 h内输注氨基酸2.0 g/(kg.d)起,每天增加0.85 g/kg,预期峰值3.7 g/(kg.d);对照组于出生24 h内输注氨基酸0.5 g/(kg.d)起,每天增加0.5 g/kg,预期峰值3.7 g/(kg.d)。结果实验组早产儿生后第1周均处于正氮平衡;对照组早产儿生后前3 d均处于负氮平衡;实验组早产儿第1周每天平均氮平衡值均大于对照组,差异有统计学意义(P均<0.01)。实验组早产儿体质量下降百分比少于对照组,差异有统计学意义(P<0.05);头围增长大于对照组,差异有统计学意义(P<0.05);达到肠内营养418.4 kJ/kg的天数、恢复出生体质量的天数和体质量达到2 000 g的天数均少于对照组,差异有统计学意义(P均<0.05)。结论早产儿生后24 h内即开始输注大剂量氨基酸(2.0 g/kg)能显著改善氮平衡,增加喂养耐受性和促进早产儿生长。     

Protein supplementation of human milk for the nutrition of VLBW-infants: human milk protein vs. meat protein hydrolysate

In 25 very low birth weight infants appropriate for gestational age the influences of different human milk (HM) preparations on weight gain, gross indices of nitrogen metabolism and energy balance were studied during the second month of postnatal life. HM was fortified either by HM-protein (HMP) or by an enzymatic meat protein hydrolysate (PH) to protein concentrations between 1.5 and 1.7 g/100 ml. The caloric densities of both HM preparations were similar between 62 and 68 kcal/100 ml. There were no differences in weight gain (MM + HMP: 18.6 +/- 3.4 g/kg/day; HM + PH: 16.5 +/- 4.1 g/kg/day), nitrogen retention (HM + HMP: 31.5 +/- 3.1 mmol/kg/day; HM + PH: 30.0 +/- 3.2 mmol/kg/day), and the preprandial estimated essential amino acid profiles between the both feeding groups. In contrast the serum concentrations of alpha-amino-nitrogen 60 minutes postprandially were elevated in the infants fed HM + PH in comparison to the infants fed HM + HMP. This high postprandial amino acid concentrations in serum in the group fed HM + PH were accompanied by increased bile acids concentrations in serum, higher renal amino acid excretion and increased fecal fat losses. The results suggest that due to the more rapid intestinal absorption of amino acids from PH than from HMP the concentrations of amino acids increase postprandially which results in a detectable increase of the newborn cholestasis in these infants. Nevertheless, the scale of these metabolic responses to feeding protein hydrolysates is small and without detectable influences on nitrogen retention or weight gain.     

Is the early and aggressive administration of protein to very low birth weight infants safe and efficacious?

PURPOSE OF REVIEW: Most conventionally managed very low birth weight infants experience postnatal growth restriction. There is some evidence that this postnatal growth restriction may have long-lasting effects, and contribute to short stature and poor neurodevelopmental outcomes. There is also evidence suggesting that early protein intake may improve growth in these very low birth weight infants. Therefore, to optimize protein intake early in the infant's neonatal course seems a logical goal. RECENT FINDINGS: Randomized controlled trials provide evidence of short-term safety and efficacy for starting amino acid infusion as soon as possible after birth at 2.5-3.0 g/kg/day in very low birth weight infants; however, there are no long-term data to support the safety or efficacy of this practice. There is some evidence from recent studies of improved growth by providing 4.0 g/kg/day of amino acid early in the neonatal period while keeping the nitrogen to energy ratio above 1:100 and continuing with this protein intake during the infants stay in the hospital. At the present time long-term safety of this strategy is also not known. SUMMARY: Appropriately designed large-scale randomized controlled trials are needed to determine the long-term safety and efficacy of early and aggressive administration of protein to very low birth weight infants.     

Glutamine supplement with parenteral nutrition decreases whole body proteolysis in low birth weight infants

OBJECTIVES: To examine the effect of supplemental glutamine (0.6 g.kg -1 .d -1 ) on whole body protein/nitrogen and glutamine kinetics in low birth weight (LBW) infants receiving parenteral nutrition in the immediate neonatal period. STUDY DESIGN: Premature infants < or =32 weeks gestation with a birth weight from 694 to 1590 g were randomly assigned to either a glutamine-supplemented group (n = 10) or to a control group (n = 10). Tracer isotope studies were performed when the infants were 6 to 7 days old and had been receiving an amino acid intake of approximately 3.0 g.kg -1 .d -1 for at least 3 days. Whole body glutamine and nitrogen kinetics were measured with [5-15N]glutamine, [2H5]phenylalanine, [1-13C, 15 N]leucine, [15N2]urea, and GC-mass spectrometry. RESULTS: Supplemental glutamine was associated with a lower rate of appearance of glutamine ( P = .003), phenylalanine ( P = .001), and leucine C ( P = .003). There was no significant difference in leucine N turnover, urea turnover and plasma cortisol, and C-reactive protein levels in the 2 groups. CONCLUSION: Parenteral glutamine supplement in LBW infants was associated with lower whole-body protein breakdown. Because the decrease in whole body proteolysis is associated with protein accretion, parenteral glutamine supplement may be beneficial in selected populations of LBW infants.     

Cord blood and postnatal serum leptin and its relationship to steroid use and growth in sick preterm infants

OBJECTIVE: To study the effect of prenatal and postnatal glucocorticoids use on serum leptin and weight gain in sick preterm infants and its correlation with caloric intake. METHODS: Serum leptin was measured in 24 neonates at day 1 (cord), 14 and 28 by radioimmunoassay. Total caloric intake (enteral and parenteral) and weight were measured on days 14 and 28 of life. RESULTS: Mean birth weight and gestational age of study infants were 864 +/- 273 g (mean +/- SD) (range 520-1755 g), and 26.6 +/- 2.4 weeks (23-32 weeks) respectively. Cord blood leptin was greater in infants whose mothers received antenatal steroids (1.98 +/- 1.05 ng/ml vs 0.94 +/- 0.39 ng/ml, p=0.004). Serum leptin increased postnatally from 1.52 +/- 1.0 ng/ml at birth to 2.2 +/- 1.3 ng/ml on day 28 of life (p=0.03). Mean serum leptin had an inverse exponential relationship with postnatal weight gain by day 28 of life (R2=0.56). Total caloric intake on days 14 and 28 of life did not correlate with postnatal weight gain. CONCLUSIONS: Increased serum concentration of leptin following glucocorticoids may be associated with poor weight gain in sick preterm infants.     

Acute effects of intravenous glutamine supplementation on protein metabolism in very low birth weight infants: a stable isotope study.

Although very low birth weight infants are subjected to severe stress and glutamine is now considered a conditionally essential amino acid that may attenuate stress-induced protein wasting in adults, current amino acid solutions designed for neonatal parenteral nutrition do not contain glutamine. To determine whether a short-term supplementation with i.v. glutamine would affect protein metabolism in very low birth weight infants, 13 preterm neonates (gestational age, 28-30 wk; birth weight, 820-1610 g) receiving parenteral nutrition supplying 1.5 g x kg(-1) x d(-1) amino acids and approximately 60 nonprotein kcal x kg(-1) x d(-1) were randomized to receive an i.v. supplement made of either 1) natural L-glutamine (0.5 g x kg(-1) x d(-1); glutamine group), or 2) an isonitrogenous glutamine-free amino acid mixture (control group), for 24 h starting on the third day of life. On the fourth day of life, they received a 2-h infusion of NaH(13)CO(3) to assess the recovery of (13)C in breath, immediately followed by a 3-h L-[1-(13)C]leucine infusion. Plasma ammonia did not differ between the groups. Glutamine supplementation was associated with 1) higher plasma glutamine (629 +/- 94 versus 503 +/- 83 microM, mean +/- SD; p < 0.05, one-tailed unpaired t test), 2) lower rates of leucine release from protein breakdown (-16%, p < 0.05) and leucine oxidation (-35%, p < 0.05), 3) a lower rate of nonoxidative leucine disposal, an index of protein synthesis (-20%, p < 0.05), and 4) no change in protein balance (nonoxidative leucine disposal - leucine release from protein breakdown, NS). We conclude that although parenteral glutamine failed to enhance rates of protein synthesis, glutamine may have an acute protein-sparing effect, as it suppressed leucine oxidation and protein breakdown, in parenterally fed very low birth weight infants.     

Glucose Tolerance in Very Low Birthweight Infants

Yu, V. Y. H., James, B. E., Hendry, P. G. and MacMahon, R. A. (1979). Aust. Paediatr. J. , 15, 147–151 Glucose tolerance in very low birthweight infants. The carbohydrate intake and incidence of hyperglycaemia were reviewed in 40 very low birthweight infants with a birthweight of less than 1200g who were randomly assigned to total parenteral nutrition (TPN) or oral (MILK) feeding regimens during the first two weeks after birth. With increasing glucose tolerance after birth, the carbohydrate intake was increased from a mean intake of 8g/kg.d on Day 1 to 17g/kg.d in the TPN group and 12g/kg.d in the MILK group by the second week; the lower intake in the latter group was due to a restricted intake rather than decreased glucose tolerance. Twenty-seven per cent of the infants had moderate or severe hyperglycaemia in the first week compared with 13% in the second week, in spite of the higher carbohydrate intake in the latter period. All hyperglycaemic episodes were corrected promptly without obvious serious sequelae by decreasing the rate of carbohydrate intake. The rational approach to carbohydrate administration in the very low birthweight infant includes the calculation of carbohydrate intake in terms of g/kg.d (rather than arbitrary concentrations given at variable rates based on fluid requirement), a constant infusion at a steady rate, and the close monitoring of blood glucose to establish glucose tolerance limits which increase with postnatal age.     

积极的营养支持对住院期间早产儿的影响

目的 探讨生后早期积极的营养支持对住院期间早产儿的影响.方法 研究对象选择胎龄大于28周出生体重1000 g至2000 g、生后12 h内转入我院NICU、住院时间2周以上、无明显畸形且存活出院的早产儿,其中A组(2005年1月1日至2006年6月30日出生)81例,B组(2009年6月1日至2010年11月30日出生)79例.比较营养摄入、早产儿的生长速率及体重Z评分和血生化营养指标的差异.结果 B组生后第3、7天氨基酸用量明显高于A组[2.00(2.00,2.50) g/kg比1.50(1.50,2.00) g/kg,3.00(2.00,3.00) g/kg比2.00(1.80,2.60) g/kg,P均＜0.001].B组第3天奶量和总热卡摄入明显高于A组[9.41(2.66,18.74) ml/kg比14.47(4.23,30.77) ml/kg,P＜0.05,(64.87±16.04) kcal/kg比(55.62±17.68) kcal/kg,P=0.001].两组第1周后总热卡摄入相似.B组母乳强化剂使用率较前升高(62.8％比14.3％,P＜0.005).无论是出生体重1000～1499 g的早产儿,还是出生体重1500～2000 g的早产儿,B组生长速率均更快[(20.6±3.4)g/( kg·d)比(15.4±3.2)g/( kg·d),(20.3±9.1)g/(kg·d)比(14.3±4.9) g/(kg·d),P均＜0.001].A组生长迟缓的比例出院时较出生时增加(65.4％比40.7％,P＜0.05),B组差异无统计学意义.两组出生体重Z评分相似,而B组出院体重Z评分明显高于A组[(-1.24±0.79)比(-1.54±0.84),P＜0.05].出生时血清白蛋白、前白蛋白、尿素水平两组差异无统计学意义,而生后2周和出院前B组明显高于A组.结论 早产儿生后早期营养措施的改善有效促进了早产儿住院期间的生长和营养状况.     

早期蛋白质和能量摄入对早产儿生长影响的研究

目的：探讨出生后早期蛋白质和能量摄入对早产儿早期生长速率的影响。方法：采用回顾性研究的方法,收集出生体重小于1800 g并治愈出院的164例早产儿的临床资料,记录早产儿一般情况、肠内外营养支持及体格增长情况。按氨基酸应用起始日的不同分为24 h内应用氨基酸组（EAA组,n=112）和24 h后应用氨基酸组（LAA组,n=52）,比较两组早产儿在住院期间的蛋白质和能量摄入、蛋白/能量比及体格增长速率,并对两组早产儿的蛋白质和能量摄入及蛋白/能量比与体格增长速率的关系进行相关分析。结果：EAA组的早产儿体重下降幅度比LAA组低（6.3% vs 8.8%）,恢复至出生体重时间比LAA组早（7 d vs 9 d）;每周头围增长速率比 LAA组快（0.79±0.25 cm vs 0.55±0.25 cm）;每日平均体重增长速率比LAA组快（20±3 g/kg vs 17±3 g/kg)。相关分析表明,早产儿第3天及第7天的蛋白质和能量摄入及蛋白/能量比与住院期间平均体重增长速率均呈正相关。恢复出生体重后每周的蛋白质和能量摄入与每周体重增长速率呈多元线性相关（r=0.709,P<0.01）。早产儿第3天及第7天的蛋白质摄入与早产儿头围增长速率及身长增长速率呈正相关。结论：早期应用氨基酸能够降低早产儿出生早期的体重下降幅度,更早恢复至出生体重,加速住院期间的体重及头围增长速度。在适宜能量摄入相对固定的情况下,在一定范围内提高蛋白质摄入量能够增加早产儿的体重、头围及身长的增长速率。     

METABOLIC CONSEQUENCES IN VERY LOW BIRTH WEIGHT INFANTS TRANSFUSED WITH OLDER AS-1-PRESERVED ERYTHROCYTES

Our study evaluated the biochemical and physiologic changes in extremely premature infants receiving AS - 1 - preserved packed red blood cells (PRBC) stored 5 to 21 days, including increase in hemoglobin, maintenance of euglycemia, and normal serum potassium levels, acid - base balance, and urine output. Twelve infants (birth weight 775 +/- 127 g) with gestational age of 25 +/- 1 weeks received small volume replacement transfusions with 17 mL /kg PRBC preserved in an AS- 1 dedicated unit. Infants were monitored throughout the transfusions and blood samples were obtained pre - and postransfusion for comparison by Student's t - test. The infants remained clinically stable throughout the transfusions and had an increase in hemoglobin of 2.5 g /dL. There was no change in urine output. Serum ammonia lactate dehydrogenase (LDH), and glucose levels were altered as predicted. There were also small, but clinically insignificant, changes in serum potassium, bicarbonate, total bilirubin, and creatinine. Euglycemia was maintained in 84 % of the transfusions. We concluded that small volume transfusions with PRBC stored up to 21 days in AS - 1 can be used in the very low birth weight infant without apparent detriment when extensive metabolic criteria are examined.     

Minimum protein intake for the preterm neonate determined by protein and amino acid kinetics

Lower limits of protein needs in prematurely born neonates have not been adequately studied, yet providing protein in amounts maximizing accretion without excess is a goal in these infants' nutritional care. We hypothesized that with the use of amino acid oxidation methodology, it would be possible to define minimum protein requirement. Our objective was to investigate protein kinetics during short-term changes in protein intake by measurement of nitrogen balance and amino acid flux and oxidation using [(15)N]glycine, [(13)C]phenylalanine, and [(13)C]leucine tracers. Protein kinetics were examined in 21 preterm infants (gestational age: 29 +/- 3 wk; birth weight: 1091 +/- 324 g) at five protein intakes (1.0, 1.5, 2.0, 2.5, and 3.0 g x kg(-1) x d(-1)) with 1 d of adaptation to the test intakes. From nitrogen balance data, a protein need of 0.74 g x kg(-1 x -1) was estimated to achieve zero balance. For all three amino acids, flux and oxidation estimates were not different across protein intakes. Whole-body protein synthesis and breakdown estimates from [(15)N]ammonia data were 14.6 +/- 3.4 and 14.4 +/- 4.1 g x kg(-1) x d(-1), respectively. Glycine flux (680 +/- 168 micromol x kg(-1) x h(-1)) was greater than leucine flux (323 +/- 115 micromol x kg(-1) x h(-1)), which was greater than phenylalanine flux (84.3 +/- 35.2 micromol x kg(-1) x h(-1)). Leucine oxidation (36.7 +/- 15.6 micromol x kg(-1) x h(-1)) was also greater than phenylalanine oxidation (6.64 +/- 4.41 micromol x kg(-1) x h(-1)). Infants in our study were able to adapt to short-term changes in protein intake with little consequence to the overall whole-body protein economy, as measured by the three test amino acids.     

Serum leptin, IGF-I and insulin levels in preterm infants receiving parenteral nutrition during the first week of life

Leptin is involved in the regulation of body weight through a feedback signal between adipose tissue and the satiety center, to decrease food intake and increase energy expenditure. Newborn infants experience physiological weight loss during the first week of life. The leptin level may be decreased to enhance food intake and to decrease energy expenditure for physiological adaptation during early postnatal days. Insulin-like growth factor-I (IGF-I) and insulin are involved in the regulation of perinatal growth. Leptin might be interrelated with IGF-I or insulin, since both of these have adipogenic and somatotropic effects. We therefore hypothesized that leptin, IGF-I and insulin would be decreased during the first week of life, concurrently with physiological weight loss. Thirty preterm AGA infants (birth weight 1.574+/-313 g; GA 31.9+/-2.2 wk) were studied. All infants received parenteral nutrition from the third day after birth. Leptin was significantly decreased during the first week of life, and insulin was significantly increased at day 7 vs. day 1 and day 3. IGF-I did not change during the first week of life. Leptin was positively correlated with body weight (r = 0.368, p<0.01), body mass index (r = 0.267, p<0.05), and serum IGF-I (r = 0.330, p <0.01), but not with serum insulin. The percent of weight reduction during the first week of life was not correlated with the percent of leptin reduction during the first week of life. In conclusion, leptin was significantly decreased and positively correlated with body weight and IGF-I during the first week of life. Changes of leptin and insulin might be related to postnatal adaptation in metabolism, but the exact role of leptin, IGF-I and insulin in postnatal physiological weight loss is not clear.