Parenteral nutrition in the newborn: a practical guide

Acidomucin goblet cell expansion induced by parenteral nutrition in the small intestine of piglets

Total parenteral nutrition (TPN) impairs small intestine development and is associated with barrier failure, inflammation, and acidomucin goblet cell expansion in neonatal piglets. We examined the relationship between intestinal goblet cell expansion and molecular and cellular indices of inflammation in neonatal piglets receiving TPN, 80% parenteral + 20% enteral nutrition (PEN), or 100% enteral nutrition (control) for 3 or 7 days. Epithelial permeability, T cell numbers, TNF-alpha and IFN-gamma mRNA expression, and epithelial proliferation and apoptosis were compared with goblet cell numbers over time. Epithelial permeability was similar to control in the TPN and PEN jejunum at day 3 but increased in the TPN jejunum by day 7. By day 3, intestinal T cell numbers were increased in TPN but not in PEN piglets. However, goblet cell expansion was established by day 3 in both the TPN and PEN ileum. Neither TNF-alpha nor IFN-gamma mRNA expression in the TPN and PEN ileum correlated with goblet cell expansion. Thus goblet cell expansion occurred independently of overt inflammation but in association with parenteral feeding. These data support the hypothesis that goblet cell expansion represents an initial defense triggered by reduced epithelial renewal to prevent intestinal barrier failure.

Selective growth of mucolytic bacteria including Clostridium perfringens in a neonatal piglet model of total parenteral nutrition

BACKGROUND

Compromised barrier function and intestinal inflammation are common complications of total parenteral nutrition (TPN).

OBJECTIVE

We tested the hypothesis that the lack of enteral nutrients in TPN might select commensal or pathogenic bacteria that use mucus as a substrate, thereby weakening the protection provided by the intestinal mucus layer.

DESIGN

Ileal microbiota profiles of piglets fed by total enteral nutrition (TEN; n = 6) or TPN (n = 5) were compared with the use of 16S ribosomal DNA polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis and with a PCR-based method developed to specifically measure Clostridium perfringens concentrations. Ileal bacteria from TEN and TPN piglets were also examined for their ability to grow on mucin or sulfated monosaccharides.

RESULTS

Bacterial community structure was equally complex in the ileum of TEN and TPN piglets, but profiles clustered according to mode of nutrition. Sixty-two percent of total mucus-associated bacteria (100 colonies tested) in TPN compared with 33% of mucus-associated bacteria (100 colonies tested) in TEN ileal samples grew on mucin. Bacteria capable of using sulfated monosaccharides were also enriched in TPN samples. C. perfringens, an opportunistic pathogen, was specifically enriched in the TPN ileum (P < 0.05). These results were corroborated by cultivation-based studies that showed rapid growth of C. perfringens on mucin-based substrates.

CONCLUSIONS

Mucolytic potential is widespread among intestinal bacteria. Mucolytic bacteria in general and C. perfringens in particular were selected when enteral nutrients were withheld in this TPN piglet model. Similar enrichment processes may occur in humans nourished by TPN and may thereby contribute to intestinal dysfunction.

Total parenteral nutrition alters molecular and cellular indices of intestinal inflammation in neonatal piglets

BACKGROUND

The adverse effects of TPN on systemic immunity are well-documented; however, the impact of IV feeding on neonatal intestinal immunity is unknown.

METHODS

A piglet TPN model was used to compare immune cell composition within the intestinal epithelium and lamina propria of parenterally and orally fed piglets.

RESULTS

Small intestinal weight of piglets maintained intravenously was reduced 50% after 7 days. Intestinal atrophy in piglets fed parenterally was evidenced by decreased width of intestinal villi and colon cuffs and reduced intestinal crypt depth. The numbers of CD4+ and CD8+ T lymphocytes were threefold greater within the lamina propria of jejunal and ileal villi of piglets supported intravenously. Inverse correlations were observed between villus height or width and T-lymphocyte numbers (r = -.80; p < .05). Major histocompatibility complex class II mRNA expression, an indicator of localized inflammation, was increased in the ileum and colon of piglets receiving parenteral nutrition. Goblet cell numbers were two-fold greater in jejunal and ileal villi, and mast cells were more abundant in the colon of piglets fed parenterally. Furthermore, jejunal T-lymphocyte numbers were correlated with goblet cell numbers (r = .80; p = .01).

CONCLUSIONS

These data identify molecular and cellular indices of intestinal inflammation that are responsive to IV feeding in neonates and provide a novel framework to investigate mechanisms underlying gut atrophy during TPN.

Nutritional support in malnourished paediatric patients

An imbalance between a person's energy requirements and his or her dietary protein and caloric supply is the source of protein energy malnutrition (PEM), which compounds the problems of any underlying disease. Malnutrition may occur quite rapidly in critically ill patients, particularly those suffering from sepsis, setting up a vicious cycle with worsening of the PEM. This chapter examines the main consequences of PEM, the means whereby appropriate nutrition may be provided, and risks for severely malnourished paediatric patients in hospital. If the gastrointestinal tract can be used for refeeding, it should be used. When the gastrointestinal tract is unable to meet the protein and energy requirements, parenteral nutrition (PN) is required. PN is efficient but carries a high risk of metabolic complications known as the refeeding syndrome and directly related to the homeostatic changes secondary to severe PEM. Catch-up growth may be achieved by using appropriate nutritional support. Changes in body composition have to be assessed during the course of renutrition.

Scientifically-based strategies for nutrition of the high-risk low birth weight infant

Technological advances in the intensive care of low birth weight (LBW) infants have resulted in major increases in their survival. New challenges in meeting their nutritional needs have emerged. Very low birth (VLBW) weight infants have very little body fat or glycogen reserves at birth, making them susceptible to starvation. If fed enterally, they require at least 120 calories/kg per day for growth. Numerous immaturities in the gastrointestinal tract and liver limit protein digestion, absorption, and metabolism. Several amino acids not considered essential to the older child or adult are essential to the VLBW infant. Supplying a high protein load with an inappropriate amino acid composition may lead to metabolic imbalances. The digestion and absorption of fats differs from the older child or adult. Lingual and gastric lipases are important, and the lack of bile acids limits fat absorption. Lipoprotein lipase deficiency causes problems when too much fat or fat of incorrect composition is provided. There are controversies regarding the most appropriate carbohydrate source, but research shows that lactose remains an important carbohydrate source for most of these infants. Calcium, magnesium, and phosphorus requirements pose questions in both enterally and parenterally nourished infants. Studies of iron usage suggest that VLBW infants fed either human milk or formula should receive iron supplements. Vitamin E may be helpful in preventing oxygen toxicity. Vitamin D deficiency contributes to bone demineralization and rickets. Controversy exists regarding the correlation between vitamin A nutrition and development of chronic lung disease. Guidelines have been developed for recommended intakes, but much needs to be learned to provide a sound scientific basis upon which to provide optimal nourishment for the high risk, LBW infant.

Calcium and phosphorus balance in Very Low Birth Weight babies on Total Parenteral Nutrition

A balance study of Ca and P has been performed in 12 Very Low Birth Wt babies receiving prolonged Total Parenteral Nutrition. The mean intake of both minerals was 54.4 mg/kg/day (range 40-70). In order to avoid the formation and precipitation of CaP crystals in the solution, fructose-1,6-diphosphate was used as a source of P. 30 balance studies were performed between the seven and 63 day of life: they were always positive with a mean retention of 47.4 mg/kg/day of Ca and 48.1 mg/kg/day of P. For both minerals, 88% of the amount infused was retained: the correlation between intake and retention was linear and statistically significative (Ca:r = 0.9, p < 0.0001; P:r = 0.68, p < 0.0001). The post-natal and post-conceptional ages of the babies had no influence on Ca and P balance. The blood levels of Ca and P were poorly correlated to both intake and excretion, and were not as indicative of the mineral balance as the retention rates calculated on the basis of the 24 h urinary excretion of the minerals. A very useful test for clinical monitoring of Ca and P balance proved to be the Ca/creatinine and P/creatinine ratios measured on simple urine samples, which were strongly correlated to 24 h excretion. All infants developed radiological signs of mild osteopenia, but there was no case of acute metabolic derangement or rickets. Our data demonstrated that even in sick VLBW infants on TPN it is possible to achieve good retention rates of Ca and P, which are not different from those observed in well VLBW babies fed a 'standard' premature formula.

Clinical studies on a newly devised amino acid solution for neonates

In 97 neonates receiving total parenteral nutrition in the postoperative period, clinical assessment was made for a newly devised amino acid solution (PF-I-III) from the standpoint of plasma amino acid profile and nutritional effect. These amino acid solutions prepared are characterized by the high concentration of branched-chain amino acids up to 40%, increased arginine and decreased glycine, phenylalanine and methionine as compared with commercially available solutions. In the PF group, each amino acid was kept within the range of standard value. Correlation between plasma amino acid profiles and the dose of each amino acid administered was obtained, from which minimum, standard, and maximum doses for each amino acid was determined. Based on these values, we proposed new formula for neonates which elicits no abnormal plasma amino acid pattern even when amino acids are administered at the dosage level of 1.5-2.5 g/kg/day.

Relationship between integrated sucking pressures and first bottle-feeding scores in premature infants

Reasons for delays in initiating premature infant bottle-feeding and the complications associated with various methods of providing nutrition to premature infants are discussed. A quantitative, correlational study was undertaken to assess premature infants' readiness to bottle-feed. Thirty premature infants, weighing 1,230 to 2,020 g were studied to determine the relationship between integrated sucking pressures and bottle-feeding scores. Sucking pressures were measured with research nipples and an electronic suckometer. Feeding ability was measured using a complex research scale and a simpler clinical scale. Feeding scales correlated significantly (r = 0.79, p less than 0.001) while sucking pressures and feeding scores did not correlate significantly. Study limitations may have been responsible for the lack of a significant correlation between sucking pressures and feeding scores. Further research is needed to establish simple, quantitative safety parameters for beginning oral feedings for premature infants.

Total parenteral nutrition in very low birth weight infants with Travasol 10% blend C

Ten very low birth weight (VLBW) infants (birth weight: 994 +/- 66 g, gestational age: 27 +/- 0.5 wk) requiring total parenteral nutrition (TPN) were studied in order to evaluate their metabolic response to the amino acid solution Travasol 10% blend C. These patients received the solution at a constant rate, providing 2.61 +/- 0.02 g/kg/day of amino acids and 76 +/- 1 kcal/kg/day. Plasma amino acids analysis was performed after 4.6 +/- 0.3 day of infusion and compared to values reported previously with Travasol blend B. The new solution (blend C) showed a significantly lower (p less than 0.001) glycinemia (485 +/- 24 vs 993 +/- 69 mumol/liter), methioninemia (39 +/- 2 vs 114 +/- 12 mumol/liter) and phenylalaninemia (67 +/- 3 vs 92 +/- 5 mumol/liter) related to the lower intake of these amino acids. Despite the provision of 47.5 mmol/liter of serine with blend C no changes in plasma level (182 +/- 15 vs 196 +/- 41 mumol/liter) were noted. The increased molar arginine/glycine ratio (blend C: 0.48 vs blend B 0.22) could have contributed to keep ammoniemia within normal levels (55.1 +/- 4.2 mumol/liter). Wide variations in insulin response (9.9 to 26.4 microU/ml) allowed for a correlation between its plasma concentration and those of sensitive amino acids, underlining its role in protein metabolism. Despite the immaturity of the study population no short-term metabolic imbalance has been encountered with the Travasol blend C solution.