Plasma amino acid patterns during supplemental intravenous nutrition of low-birth-weight infants

Higher versus lower amino acid intake in parenteral nutrition for newborn infants

BACKGROUND

Sick newborn and preterm infants frequently are not able to be fed enterally, necessitating parenteral fluid and nutrition. Potential benefits of higher parenteral amino acid (AA) intake for improved nitrogen balance, growth, and infant health may be outweighed by the infant's ability to utilise high intake of parenteral AA, especially in the days after birth.

OBJECTIVES

The primary objective is to determine whether higher versus lower intake of parenteral AA is associated with improved growth and disability-free survival in newborn infants receiving parenteral nutrition.Secondary objectives include determining whether:• higher versus lower starting or initial intake of amino acids is associated with improved growth and disability-free survival without side effects;• higher versus lower intake of amino acids at maximal intake is associated with improved growth and disability-free survival without side effects; and• increased amino acid intake should replace non-protein energy intake (glucose and lipid), should be added to non-protein energy intake, or should be provided simultaneously with non-protein energy intake.We conducted subgroup analyses to look for any differences in the effects of higher versus lower intake of amino acids according to gestational age, birth weight, age at commencement, and condition of the infant, or concomitant increases in fluid intake.

SEARCH METHODS

We used the standard search strategy of the Cochrane Neonatal Review Group to search the Cochrane Central Register of Controlled Trials (2 June 2017), MEDLINE (1966 to 2 June 2017), Embase (1980 to 2 June 2017), and the Cumulative Index to Nursing and Allied Health Literature (CINAHL) (1982 to 2 June 2017). We also searched clinical trials databases, conference proceedings, and citations of articles.

SELECTION CRITERIA

Randomised controlled trials of higher versus lower intake of AAs as parenteral nutrition in newborn infants. Comparisons of higher intake at commencement, at maximal intake, and at both commencement and maximal intake were performed.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials, assessed trial quality, and extracted data from included studies. We performed fixed-effect analyses and expressed treatment effects as mean difference (MD), risk ratio (RR), and risk difference (RD) with 95% confidence intervals (CIs) and assessed the quality of evidence using the GRADE approach.

MAIN RESULTS

Thirty-two studies were eligible for inclusion. Six were short-term biochemical tolerance studies, one was in infants at > 35 weeks' gestation, one in term surgical newborns, and three yielding no usable data. The 21 remaining studies reported clinical outcomes in very preterm or low birth weight infants for inclusion in meta-analysis for this review.Higher AA intake had no effect on mortality before hospital discharge (typical RR 0.90, 95% CI 0.69 to 1.17; participants = 1407; studies = 14; I² = 0%; quality of evidence: low). Evidence was insufficient to show an effect on neurodevelopment and suggest no reported benefit (quality of evidence: very low). Higher AA intake was associated with a reduction in postnatal growth failure (< 10th centile) at discharge (typical RR 0.74, 95% CI 0.56 to 0.97; participants = 203; studies = 3; I² = 22%; typical RD -0.15, 95% CI -0.27 to -0.02; number needed to treat for an additional beneficial outcome (NNTB) 7, 95% CI 4 to 50; quality of evidence: very low). Subgroup analyses found reduced postnatal growth failure in infants that commenced on high amino acid intake (> 2 to ≤ 3 g/kg/day); that occurred with increased amino acid and non-protein caloric intake; that commenced on intake at < 24 hours' age; and that occurred with early lipid infusion.Higher AA intake was associated with a reduction in days needed to regain birth weight (MD -1.14, 95% CI -1.73 to -0.56; participants = 950; studies = 13; I² = 77%). Data show varying effects on growth parameters and no consistent effects on anthropometric z-scores at any time point, as well as increased growth in head circumference at discharge (MD 0.09 cm/week, 95% CI 0.06 to 0.13; participants = 315; studies = 4; I² = 90%; quality of evidence: very low).Higher AA intake was not associated with effects on days to full enteral feeds, late-onset sepsis, necrotising enterocolitis, chronic lung disease, any or severe intraventricular haemorrhage, or periventricular leukomalacia. Data show a reduction in retinopathy of prematurity (typical RR 0.44, 95% CI 0.21 to 0.93; participants = 269; studies = 4; I² = 31%; quality of evidence: very low) but no difference in severe retinopathy of prematurity.Higher AA intake was associated with an increase in positive protein balance and nitrogen balance. Potential biochemical intolerances were reported, including risk of abnormal blood urea nitrogen (typical RR 2.77, 95% CI 2.13 to 3.61; participants = 688; studies = 7; I² = 6%; typical RD 0.26, 95% CI 0.20 to 0.32; number needed to treat for an additional harmful outcome (NNTH) 4; 95% CI 3 to 5; quality of evidence: high). Higher amino acid intake in parenteral nutrition was associated with a reduction in hyperglycaemia (> 8.3 mmol/L) (typical RR 0.69, 95% CI 0.49 to 0.96; participants = 505; studies = 5; I² = 68%), although the incidence of hyperglycaemia treated with insulin was not different.

AUTHORS' CONCLUSIONS

Low-quality evidence suggests that higher AA intake in parenteral nutrition does not affect mortality. Very low-quality evidence suggests that higher AA intake reduces the incidence of postnatal growth failure. Evidence was insufficient to show an effect on neurodevelopment. Very low-quality evidence suggests that higher AA intake reduces retinopathy of prematurity but not severe retinopathy of prematurity. Higher AA intake was associated with potentially adverse biochemical effects resulting from excess amino acid load, including azotaemia. Adequately powered trials in very preterm infants are required to determine the optimal intake of AA and effects of caloric balance in parenteral nutrition on the brain and on neurodevelopment.

Changes in urinary amino acid fractional excretion in neonates undergoing total parenteral nutrition

The paper examines the possible reasons why there was a different weight gain pattern in two groups of sick neonates fed two different amino acid solutions during a prospective double-blind trial of otherwise identical total parenteral nutrition. During the 13-month study period, 14 neonates (eight less than 32 weeks gestation) received Vamin as their amino acid source, and 18 (eight less than 32 weeks gestation) received a new amino acid solution, Paedmin. The older group of neonates gained weight far better when fed Vamin (P less than 0.003), neonates of less than 32 weeks gestation gained weight better when fed Paedmin (P less than 0.004). These differences in weight gain were reflected in differences in plasma amino acid concentration in that the levels were lower in the groups gaining weight less well; and in urinary fractional excretion where the groups gaining weight less well had a markedly higher fractional excretion and total urinary loss of amino acids (P less than 0.001). It is suggested that these differences in amino acid handling of two different amino acid solutions may lead to differences in weight gain.

A double blind comparison of a new paediatric amino acid solution in neonatal total parenteral nutrition

All infants requiring parenteral nutrition over a continuous 13-month period were allocated to receive either Vamin or a new paediatric amino acid solution, Paedmin, as their protein source in a double blind prospective study. Those of 32 weeks gestation and less gained weight more rapidly when fed Paedmin than Vamin (P less than 0.004), but there were significant changes in liver function after 14 days nutrition. Babies of 33 weeks gestation and greater gained weight more rapidly when fed Vamin than Paedmin (P less than 0.003) but without liver function changes. There were no differences in the rate of head growth. Amino acid analysis of serum and urine showed a greater urinary loss of amino acids for a given serum concentration in babies of 32 weeks and less for both nutrition groups. The apparent benefit of Paedmin in the immature group of infants must be further evaluated and weighed against changes in liver function.

Nutritional support: how much for how much?

Although malnutrition is associated with poor clinical outcome, it cannot be inferred that better nutrition will improve clinical outcome. Efficacy of a proposed regimen is best established by prospective, randomised, controlled trials. Cost effectiveness is only an issue if efficacy exists. Patients with long term temporary, or permanent, inadequate bowel syndrome are candidates for parenteral nutrition. Most of the prospective, randomised, controlled trials testing the value of nutritional support in other diseases, however, have failed to show that this treatment has a beneficial clinical effect. Areas where these trials have shown a possible clinical benefit include the perioperative care of patients with upper gastrointestinal cancer, elemental diet treatment of Crohn's disease, and branched chain amino acid infusions in hepatic encephalopathy. Even in these instances, it is not clear that such treatment will prove to be cost effective (compared with other currently available treatments).

Plasma amino acids in supplementary parenteral nutrition of preterm infants. Effect of different quantities of amino acid infusion and comparison with enteral feeding

The present investigation aims to determine quantity and quality of the amino acid (AA) solution to be used in supplementary parenteral nutrition (SPN). We established the plasma AA concentrations of preterm infants (birthweight 1160-1940 g, mean 1540; gestational age 29-30 weeks, mean 32) divided into three groups. Group I (n = 11) and group II (n = 12) were put on a standardised SPN regimen starting with an intravenous supply of 2.5 resp. 1.5 g AA/kg/day. Infants of group III were formula-fed, and served as controls. A total of 231 aminograms was obtained during the first two weeks of age. Comparison of groups I and II to group III revealed plasma accumulation of six AA in group I. Supplementation in group II resulted in a normal pattern, except alanine, proline, and methionine. However, only deviations of proline and methionine may be judged as imbalances, and lowering in composition may be considered. We conclude that the low intravenous AA intake employed in group II may be preferred in SPN of preterm infants.

Amino acids in parenteral nutrition of preterm infants. Comparison of oral and parenteral supply

Parenteral feeding of preterm infants has been accepted as an alternative form of nutrition in those infants unable to accept oral feeding. The amount of amino acid nitrogen and the composition of the amino acid solution to be used, however, have not yet been defined. The amino acid intake and the plasma amino acid concentration of three groups of preterm infants were compared. Twenty-three infants were fed parenterally. Of these, 16 were studied during the first week of life (group I) and 7 during the second week (group II). A control group of 9 infants fed with oral formula was also studied in the second week (group III). In general, plasma amino acid concentrations in the parenterally fed groups were higher than in the orally fed group, in spite of a lower intake. Comparison of the amino acid intake of groups I and II relative to group III, with the plasma amino acid concentrations of groups I and II relative to group III, revealed a rather constant ratio with the exception of tyrosine and aspartic acid, where higher values were found. It is concluded that further increase in the amino acid nitrogen in parenteral feeding of preterm infants requires a more adapted preparation.

Gastroenteritis in a regional hospital in Kuwait: some aspects of the disease

A review of the clinical course of gastroenteritis in 274 hospitalized children revealed a severe form of the disease. Eight-eight per cent were aged 12 months or under and 20% had severe associated malnutrition. The commonest clinical manifestations were diarrhoea (100%), dehydration (98.9%), vomiting (81.4%) and fever (77.7%). Pathogens were isolated from 75.2% of cases (rotavirus 24.5%, Escherichia coli 20.8%, salmonellae 20%, shigellae 6.2%, campylobacter 2.2% and Yersinia enterocolitica in 1.5%). Septicaemia was confirmed in 12 patients (4.4%) and strong clinical evidence of septicaemia was present in 36 more cases (13%). Dehydration was isonatraemic in 68%, hyponatraemic in 21% and hypernatraemic in 11% of cases. There was a clear association between septicaemia and hyponatraemia. The overall mortality rate was 1.8%. Data from our study show that the use of intravenous hyperalimentation, and/or antibiotics in the management of gastroenteritis in selected patients, can significantly reduce morbidity and mortality.

The prospects for amino acid infusion

Amino acid preparations for intravenous infusion are indispensable materials in parenteral nutrition. We have surveyed the progress and problems related to such preparations. In recent years, the necessity of various amino acid preparations suitable for different morbid state and/or ages has been the subject of much interest. In practice, several new amino acid preparations for specific uses have been proposed.

Total parenteral nutrition in very low birthweight infants: a controlled trial

34 preterm infants with birthweights <1200 g were randomly assigned to total parenteral nutrition (TPN) or oral (Milk) feeding regimens for the first 2 weeks after birth. Infants in the TPN group were started on a modified Vamin-based glucose amino-acid infusion and Intralipid. The daily amounts of carbohydrate, amino-acids, and fat infusions were increased. In the Milk group, infants were started on intermittent gavage feeding, supplemented with a glucose-electrolyte infusion as necessary. The overall mortality rate did not differ in the two groups. Four infants in the Milk group developed necrotising enterocolitis but none did in the TPN group. Despite mean daily energy intakes which were not greatly different, there were much higher mean daily intakes of carbohydrate and protein in the TPN group compared with the Milk group. Fat intake in the TPN group was lower than in the Milk group in the 1st week because of neonatal jaundice which contraindicated the use of Intralipid. There was no difference in the mean daily fat intake by the 2nd week. Although mean daily weight loss in the 1st week and the maximum postnatal weight loss in the two groups were similar, infants in the TPN group had a greater mean daily weight gain in the 2nd week and took less time to regain and maintain birthweight. Metabolic complications were equally common in both groups and were reversible with early recognition. Limits of tolerance for water and most nutrients tended to be variable and the nutritional programme had to be adjusted for each baby. Nevertheless, we found that TPN, when properly managed, is an effective and safe procedure in very low birthweight infants.

Plasma free amino acid concentrations of breast-fed infants

Photometric determination of alpha-amino nitrogen in peripheral venous plasma and urine from 20 healthy, full-term infants, 1--5 months of age, showing normal growth and development during an uncomplicated lactation, revealed lower plasma levels than what has been found in adults, or 3.7 +/- 1.1 mg/100 ml, and a urinary excretion of 41 +/- 14 mg/24 hours. Ion-exchange chromatography of deproteinized peripheral venous plasma showed low valine concentrations, an increased glycine/valine ratio and high cystine and very high taurine levels when compared to the levels of healthy American infants of comparable ages fed 3--3.5 g/kg of cow-milk protein. The findings indicate that a formula based on cow-milk protein should optimally contain only 1.0--1.2 g protein/100 ml provided that it is "humanized" not only with regard to the lactalbumin/casein ratio, but also to the cystine and taurine content. The pattern of the plasma concentrations of free amino acids reported in the present investigation may be used as a normal reference for breast-fed infants.

A syndrome of methylmalonic aciduria, homocystinuria, megaloblastic anemia and neurologic abnormalities in a vitamin B12-deficient breast-fed infant of a strict vegetarian

We studied a six-month-old infant with severe megaloblastic anemia, coma and hyperpigmentation of the extremities. He was found to have methylmalonic aciduria (79 mumol per milligram of creatinine) and homocystinuria (0.85 mumol per milligram of creatinine). Additional biochemical abnormalities included cystathioninuria, glycinuria, methylcitric aciduria, 3-hydroxypropionic aciduria and formic aciduria. The concentration of vitamin B12 in the serum was 20 pg per milliliter. This severe nutritional deficiency was a consequence of inadequate intake, for the infant was exclusively breast-fed by a strictly vegetarian mother who manifested methylmalonic aciduria. Our observations emphasize the importance of educating strict vegetarians about the deficiency of vitamin B12 in their diets and the importance of vitamin B12 supplementation.

Peripheral total parenteral nutrition for premature infants with the respiratory distress syndrome: a controlled study

In 40 premature infants, in whom severe respiratory distress precluded oral feeding, peripheral total parenteral nutrition consisting of casein hydrosylate, dextrose, and soybean emulsion was compared to nutrition with dextrose and electrolytes. The TPN group received more calories, and the total serum protein in them increased significantly. Metabolic complications did not occur. Transient thrombocytosis occurred in six infants who received TPN and eosinophilia occurred in nine. The case fatality rate in the TPN group (three of 20) was not significantly less than in the glucose group (six of 20). The differences suggested that infants who weigh less than 1,500 gm may receive the greater benefit from TPN.

Total parenteral nutrition in pediatrics

Parenteral nutrition (p.N.) is indicated whenever oral food intake is partly or completely disturbed. The objective of this type of treatments is to provide the organism with sufficient nutrients and maintain the structure and growth. The supply of an optimum mixture of water, protein, carbohydrates, fats, minerals, vitamins and trace elements is a prerequisite for this. In the following parts of this study the indications for p.N., the technique and requirements for different nutrients, minerals, trace elements and vitamins are presented. A type of amino acid mixture especially prepared for pediatric use is prevented and new results of t.p.N. are discussed. In the following parts of this study the indications for p.N., the technique and practice of the infusion programme, the clinical and laboratory investigation of t.p.N., the complications and their prophylaxis during the p.N. are discussed. The goal of better total parenteral nutrition is approached when dosage, infusion rate, contraindications and the guidelines discussed here are observed. We will, however, continue the work for a further improvement of intravenous nutrition.

Total parenteral alimentation via indwelling umbilical catheters in the newborn period

Total parenteral alimentation (TPA) was delivered to 80 infants via indwelling umbilical artery and to 9 via indwelling umbilical venous catheters. The primary indication for catheter placement and maintenance was monitoring of arterial blood gases (umbilical venous catheter tip in left atrium) in a group of sick neonates requiring increased inspired oxygen or assisted ventilation. Results were compared with those from 23 infants who had tunnelled jugular catheters for a variety of chronic medical and surgical problems preventing gastric or intestinal feeding. A mean weight gain was achieved in both groups. Mortality and morbidity rates were similar in both groups. The most common complications were infection and thrombotic phenomena. Metabolic complications were few. It is concluded that infusing TPA solutions via indwelling umbilical catheters presents no greater risk than infusion via tunnelled jugular catheters, and provides a method for supplying adequate caloric intake for growth during the acute stage of illness.

Difficulties and pitfalls in the interpretation of screening tests for the detection of inborn errors of metabolism

A review of factors which may be responsible for false positive and false negative results in a screening program for the detection of inborn errors of metabolism is presented. Administration of medication, dietary therapy, chemical treatment of specimens, delay in analysis, hypersensitivity of procedures utilized, interfering metabolites and inadequate metabolic development or enzymatic maturation in the patient may all produce results resembling an actual inborn error of metabolism. Inadequate nutritional intake prior to procurement of specimen and loss of material during analytical procedures may produce false negative results. As well, certain less severe variants of inborn errors may present in an unusual manner or may only present during periods of stress to the patient. These factors are discussed in relation to the performance of a metabolic screening program. It is suggested that these progrms should be performed by specialized, central laboratories experienced in the complexities of detection of inborn errors of metabolism.

[Investigations on the utilization of parenterally administered amino acids in premature and small-for-dates neonates. IV. Control of the amino acid blood level during infusion of a pharmacokinetically balanced amino acid solution (author's transl)]

An amino acid solution composed according to pharmacokinetic criteria was infused in 12 premature and 4 full-term infants. Imbalances of amino acids were not observed when the upper limit of the fasting level was accepted as a measure for balance or imbalance. The net transfer of total amino acids increased by about 40% over that in former experiments (second communication (4)). A decrease of cystine, a semiessential amino acid, could be avoided. The results were compared with the literature. During infusion, the urinary excretion of amino acids was not increased showing nearly complete utilization of the infused amin acids.

Amino acid precursors of monoamine neurotransmitters and some factors influencing their supply to the brain

There is evidence that changes in the concentrations of the monoamine neurotransmitters within the brain are associated with changes in mental processes, with disorders of control of movement and with certain neuropsychiatric diseases. These neurotransmitters are synthesized in the brain from aromatic amino acid precursors that have to be obtained from the circulating blood. In this study some factors which alter the rates of entry of four amino acids (the important neurotransmitter precursors L-tyrosine and L-tryptophan, as well as L-phenylalanine and L-histidine) into the brain have been studied and the findings considered in relation to conditions in which the quantities of one or more of the monoamine neurotransmitters formed within the cerebral cells may be either too large or too small. Thus too little neurotransmitter will be formed if competition between amino acids for the carriers transporting them into the cerebral cells causes the exclusion of a large proportion of any of the aromatic amino acid precursors from the brain. ,or example, L-tryptophan is partially excluded from the brain if a raised level of any one of several other amino acids is maintained in the circulation. Of these, L-phenylalanine inhibits the transport of L-tryptophan into the brain most effectively, while aromatic amino acids in general exclude L-tryptophan more effectively than do other neutral amino acids. Over-production of one or more of the monoamine neurotransmitters is likely to occur when there is too much of one of the aromatic amino acid precursors in the brain cells as a result of abnormally high uptake from the blood, or as a result of their release by an excessive breakdown of the protein within these cells. Underproduction of neurotransmitters may occur in certain disease states, such as some aminoacidurias or Parkinsonism. We have listed some conditions associated with altered mental states or motor disability in which over- or under-production of monoamine neurotransmitters may occur and have tried to relate the findings in human disease with our experimental results.