Malnutrition in the premature infant

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.

Aggressive parenteral nutrition in sick very low birth weight babies: a randomized controlled trial

Survival of preterm neonates in developing world has improved. Developing countries lag behind in nutritional management in NICU especially parenteral nutrition (PN). This randomized controlled trial was done to evaluate the effect of aggressive parenteral nutrition on nitrogen retention of sick VLBW and extremely low birth weight (ELBW) babies. From September 2009 to February 2010, total 34 babies were randomized to receive aggressive parenteral nutrition (APN)(n=17) or standard parenteral nutrition (SPN) (n=17). The average daily total and PN calory intake of babies in APN group was significantly higher during first week. APN was well-tolerated; however, nitrogen retention was not significantly higher in APN group. Aggressive parenteral nutrition in sick VLBW babies is feasible in developing world, though it did not improve nitrogen retention in first week of life.

The contribution of body protein to the supply of energy in starved newborn piglets is not preferentially suppressed by intravenous provision of glucose and fat

Newborn piglets were used to study body protein preservation because it is critical to the survival of premature infants. Quantitative estimates of endogenous fuel use were obtained from 12 to 72 h of age in male piglets. Of the 40 piglets used (1300 +/- 205 g, mean +/- SD), 16 served as a 12-h-old body composition reference (R), 16 were starved (S) and received water only, and 8 received supplemental energy (E), obtaining 70% [210 kJ/(kg x d)] of their resting energy requirement as an i.v. mixture of glucose and Intralipid (65:35 energy ratio). Urine was collected continuously from the bladder via an umbilical urachal catheter. Total body water, glycogen, lipid, ash, and Kjeldahl-N were determined on whole-pig homogenates. Comparative slaughter was used to estimate the disappearance of body constituents of S and E pigs from 12 to 72 h of age. Midpoint body weight was used in these calculations. Supplemental energy decreased use of all body energy sources as indicated by the decrease in body dry matter disappearance, 41.6 +/- 8.8 vs. 25.5 +/- 5.9 g/kg (P = 0.0021) and protein (urinary N excretion), 995 +/- 508 vs. 329 +/- 135 mg/kg (P = 0.0119) over 60 h. Supplemental energy did not preferentially spare the percentage of the resting energy expenditure supplied by endogenous body protein (protein 37.6% +/- 9.6 vs. 41.7% +/- 10.4; lipid 25.7% +/- 5.2 vs. 20% +/- 4.1; glycogen 36.8% +/- 7.5 vs. 38.3% +/- 9.9; S vs. E) because it made up approximately 40% of the total in food-deprived and supplemented piglets.

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.

Continuous insulin intravenous infusion therapy for VLBW infants

Very low birth weight (VLBW) infants less than 1,000 g often experience hyperkalemia and hyperglycemia during the initial hospital course. Hyperkalemia has been noted in 44% to 50% of infants less than 800 g birth weight or less than 28 to 29 weeks' gestation. Hyperglycemia occurs 18 times more frequently in infants less than 1,000 g than in those weighing more than 2,000 g. Insulin has been used for VLBW infants less than 1,000 g to manage hyperkalemia, control hyperglycemia, and optimize parenteral nutrition. A protocol for using exogenous insulin therapy for VLBW infants is described.