Role of feeding in the pathogenesis of necrotizing enterocolitis

Early gradual feeding with bovine colostrum improves gut function and NEC resistance relative to infant formula in preterm pigs

It is unclear when and how to start enteral feeding for preterm infants when mother's milk is not available. We hypothesized that early and slow advancement with either formula or bovine colostrum stimulates gut maturation and prevents necrotizing enterocolitis (NEC) in preterm pigs, used as models for preterm infants. Pigs were given either total parenteral nutrition (TPN, n = 14) or slowly advancing volumes (16-64 ml·kg(-1)·day(-1)) of preterm infant formula (IF, n = 15) or bovine colostrum (BC, n = 13), both given as adjunct to parenteral nutrition. On day 5, both enteral diets increased intestinal mass (27 ± 1 vs. 22 ± 1 g/kg) and glucagon-like peptide 2 release, relative to TPN (P < 0.05). The incidence of mild NEC lesions was higher in IF than BC and TPN pigs (60 vs. 0 and 15%, respectively, P < 0.05). Only the IF pigs showed reduced gastric emptying and gastric inhibitory polypeptide release, and increased tissue proinflammatory cytokine levels (IL-1β and IL-8, P < 0.05) and expression of immune-related genes (AOAH, LBP, CXCL10, TLR2), relative to TPN. The IF pigs also showed reduced intestinal villus-to-crypt ratio, lactose digestion, and some plasma amino acids (Arg, Cit, Gln, Tyr, Val), and higher intestinal permeability, compared with BC pigs (all P < 0.05). Colonic microbiota analyses showed limited differences among groups. Early feeding with formula induces intestinal dysfunction whereas bovine colostrum supports gut maturation when mother's milk is absent during the first week after preterm birth. A diet-dependent feeding guideline may be required for newborn preterm infants.

Effect of Bifidobacterium breve M-16V supplementation on fecal bifidobacteria in preterm neonates--a randomised double blind placebo controlled trial

BACKGROUND

Probiotic supplementation significantly reduces the risk of necrotising enterocolitis (NEC) and all cause mortality in preterm neonates. Independent quality assessment is important before introducing routine probiotic supplementation in this cohort.

AIM

To assess product quality, and confirm that Bifidobacterium breve (B. breve) M-16V supplementation will increase fecal B. breve counts without adverse effects.

METHODS AND PARTICIPANTS

Strain identity (16S rRNA gene sequencing), viability over 2 year shelf-life were confirmed, and microbial contamination of the product was ruled out. In a controlled trial preterm neonates (Gestation <33 weeks) ready to commence or on feeds for <12 hours were randomly allocated to either B. breve M-16V (3×109 cfu/day) or placebo (dextrin) supplementation until the corrected age 37 weeks. Stool samples were collected before (S1) and after 3 weeks of supplementation (S2) for studying fecal B. breve levels using quantitative PCR (Primary outcome). Secondary outcomes included total fecal bifidobacteria and NEC≥Stage II. Categorical and continuous outcomes were analysed using Chi-square and Mann-Whitney tests, and McNemar and Wilcoxon signed-rank tests for paired comparisons.

RESULTS

A total of 159 neonates (Probiotic: 79, Placebo: 80) were enrolled. Maternal and neonatal demographic characteristics were comparable between the groups. The proportion of neonates with detectable B. breve increased significantly post intervention: Placebo: [S1:2/66 (3%), S2: 25/66 (38%), p<0.001] Probiotic: [S1: 29/74 (40%), S2: 67/74 (91%), p<0.001]. Median S1 B. breve counts in both groups were below detection (<4.7 log cells x g(-1)), increasing significantly in S2 for the probiotic group (log 8.6) while remaining <4.7 log in the control group (p<0.001). There were no adverse effects including probiotic sepsis and no deaths. NEC≥Stage II occurred in only 1 neonate (placebo group).

CONCLUSION

B. breve M-16V is a suitable probiotic strain for routine use in preterm neonates.

TRIAL REGISTRATION

Australia New Zealand Clinical Trial Registry ACTRN 12609000374268.

Enteral feeding practices in the NICU: results from a 2009 Neonatal Enteral Feeding Survey

PURPOSE

: The purpose of this study was to examine the current management of the enteral feeding regimens of premature infants cared for in the neonatal intensive care unit (NICU).

SUBJECTS

: The study included responses from 70 neonatal nurses who participated in a 2009 Neonatal Enteral Feeding Survey distributed electronically to the National Association of Neonatal Nurses membership. These respondents were representative of both the United States and Canada, with 29 US states represented. The majority of respondents (95.7%) reported current nursing employment in a level III NICU.

DESIGN

: Survey research was used in this exploratory study. The survey, Enteral Tube Feeding Practices in the Neonatal Intensive Care Unit, was developed in collaboration with expert neonatal nurses and nutritionists, pilot tested, and distributed via electronic means.

METHODS

: Survey research was conducted according to the Dillman methodology. Data analysis included descriptive statistics and univariate analysis of variance assessing for significant differences in specific neonatal feeding practices reported. Thematic analysis was used to analyze the qualitative data reported.

OUTCOME MEASURES

: The outcome measures included the survey responses to the questions asked about the implementation of an enteral feeding protocol and various aspects of enteral feeding practices in the NICU.

RESULTS

: The majority of participants (60.9%) reported that an enteral feeding protocol was implemented in practice, but that it was inconsistently followed because of individual physician or nurse practice patterns, or highly individualized feeding plans required of specific clinical care needs of the patient. Respondents indicated that gestational age was the leading criteria used to initiate feedings, and patent ductus arteriosis treatment was the primary contraindication to enteral feedings. The leading factor reported to delay or alter enteral feedings was the presence of gastric residuals. Survey data indicated that other contraindicating factors to enteral feeding are variable across NICUs and, as reported, are often inconsistent with the current research published to date.

CONCLUSIONS

: Research is needed to provide a foundation on which to develop effective enteral feeding protocols that are appropriate for the diversity of infants cared for in the NICU. Such research findings will culminate in the development and implementation of enteral feeding protocols in the NICU, which will result in improved nutrition, growth, and development outcomes for premature infants.

Evidence-based guidelines for use of probiotics in preterm neonates

BACKGROUND

Current evidence indicates that probiotic supplementation significantly reduces all-cause mortality and definite necrotising enterocolitis without significant adverse effects in preterm neonates. As the debate about the pros and cons of routine probiotic supplementation continues, many institutions are satisfied with the current evidence and wish to use probiotics routinely. Because of the lack of detail on many practical aspects of probiotic supplementation, clinician-friendly guidelines are urgently needed to optimise use of probiotics in preterm neonates.

AIM

To develop evidence-based guidelines for probiotic supplementation in preterm neonates.

METHODS

To develop core guidelines on use of probiotics, including strain selection, dose and duration of supplementation, we primarily used the data from our recent updated systematic review of randomised controlled trials. For equally important issues including strain identification, monitoring for adverse effects, product format, storage and transport, and regulatory hurdles, a comprehensive literature search, covering the period 1966-2010 without restriction on the study design, was conducted, using the databases PubMed and EMBASE, and the proceedings of scientific conferences; these data were used in our updated systematic review.

RESULTS

In this review, we present guidelines, including level of evidence, for the practical aspects (for example, strain selection, dose, duration, clinical and laboratory surveillance) of probiotic supplementation, and for dealing with non-clinical but important issues (for example, regulatory requirements, product format). Evidence was inadequate in some areas, and these should be a target for further research.

CONCLUSION

We hope that these evidence-based guidelines will help to optimise the use of probiotics in preterm neonates. Continued research is essential to provide answers to the current gaps in knowledge about probiotics.

Análise das práticas de alimentação de prematuros em maternidade pública no Rio de Janeiro

OBJETIVO: Analisar as práticas precoces de alimentação e o tipo de dieta de prematuros na alta hospitalar. MÉTODOS: Estudo descritivo, a partir de uma coorte retrospectiva de dois anos, com 203 prematuros com peso menor que 1 500g, na maternidade do Hospital Geral de Bonsucesso, Rio de Janeiro. Foram avaliadas as seguintes práticas: dias para início de dieta enteral, dias para atingir a dieta enteral plena, dias para início e tempo de uso de nutrição parenteral e o tipo de dieta na alta hospitalar. RESULTADOS: O tempo médio para início de dieta enteral foi de 6,5 dias (IC95% 6,0-7,2), enquanto para atingir a dieta enteral plena levou-se, em média, 18,9 dias (IC95% 17,6-20,3). A média de dias para início de nutrição parenteral foi de 2,8 dias (IC95% 2,6-3,0) e o tempo de uso de nutrição parenteral foi de 10,8 dias (IC95% 9,7-11,9). As práticas se associaram, sendo encontrada a maior correlação entre dias para atingir dieta plena e dias de uso de nutrição parenteral (Pearson=0,69). Quanto menor o peso de nascimento, maior o tempo para início de dieta enteral, para atingir a dieta enteral plena e de uso de nutrição parenteral. Para o início de nutrição parenteral, não foi observada esta tendência. Na alta, o tipo de dieta mais freqüente foi o aleitamento complementado (61,6%), seguido da alimentação artificial (26,1%) e do aleitamento materno exclusivo (12,3%). CONCLUSÃO: Este estudo revelou que há demora em iniciar a alimentação de prematuros. A proporção total de aleitamento na alta foi de 74%. Esforços merecem ser envidados para alimentar precocemente e promover o aleitamento materno nestes pacientes.

Clinical predictors of necrotizing enterocolitis in premature infants

BACKGROUND

Necrotizing enterocolitis (NEC) has emerged as the most common neonatal gastrointestinal emergency, is the most common cause of death in neonates undergoing surgery, and accounts for yearly additional hospital charges in excess of $6.5 million. Prematurity is the only common variable identified in case-controlled studies exploring this disease.

OBJECTIVES

To improve the understanding of the relationship between factors related to intestinal inflammation and ischemia and the enteral feeding regimen in the context of the premature gut, thereby identifying antecedents of NEC.

METHODS

Data were collected from the medical records of 247 premature infants for this retrospective case-controlled study. Diagnosis of NEC, as defined by Bell Stages IIA-IIIB, was required for study group assignment (n = 84). Multivariate analysis techniques were used to predict the relationships between selected variables on the outcome of NEC.

RESULTS

Premature infants were 13 times more likely to develop NEC if the infant required increased respiratory support to maintain oxygenation during the early neonatal period and 6.4 times more likely to develop NEC if the infant did not receive nutritionally fortified enteral feedings of breast milk. When both factors were present, the odds of NEC increased 28.6 times when compared with infants without these factors.

DISCUSSION

The study findings extend knowledge of antecedents to NEC beyond prematurity, highlighting the role that respiratory support and nutritional fortification of enteral feedings play in the pathogenesis of this disease. Early identification of antecedents to NEC will improve critical care management of the neonate and, in turn, decrease the incidence of this devastating gastrointestinal disease. The study findings will guide further inquiry in neonatal nutrition, physiologic and metabolic functioning, and acute clinical management of the neonate.

Prevention and treatment of necrotising enterocolitis in preterm neonates

Prevention and treatment of NEC has become an area of priority for research due to the increasing number of preterm survivors at risk, and the significant mortality and morbidity related to the illness. Probiotic supplementation appears to be a promising option for primary prevention of NEC but further large trials are necessary for documenting their safety in terms of sepsis as well as long-term neurodevelopmental outcomes and immune function. As new frontiers including immunomodulating agents like pentoxifylline continue to be explored, the impact of well-established simple strategies like antenatal glucocorticoid therapy, and early and preferential use of breast milk must not be forgotten. Clinical research on manifestations of ileus of prematurity, and feeding in the presence of common risk factors such as IUGR is needed. Safety of minimal enteral feeds in terms of NEC and benefits of standardised feeding regimens need to be confirmed. Association of common clinical practices such as red cell transfusions, H2 receptor blockade, and thickening of feeds with NEC warrants attention. An approach utilising a package of potentially better practices seems to be the most appropriate strategy for the prevention and treatment of NEC.

Survey of the current practices for neonatal gastrointestinal contrast studies in Australia

A wide range of contrast agents with varying osmolality (290-849 mmol/kg) and iodine content (150-370 mg/mL) are currently available for neonatal gastrointestinal contrast studies. A nationwide survey was hence conducted to identify current practices. A questionnaire was mailed to the 22 Australian neonatal units registered with the Australian and New Zealand Neonatal Network. Seventeen (72%) of the 22 units responded to the questionnaire and 54% had some guidelines for term neonates. No unit had a specific policy for preterm neonates. Seventy-seven per cent of the respondents used a contrast agent with a high osmolality. There was a wide variation in the volume and dilution of contrast used. Guidelines for gastrointestinal contrast studies in high-risk neonates are suggested.

Strategies for prevention of feed intolerance in preterm neonates: a systematic review

Postnatal growth restriction and failure to thrive have been recently identified as a major issue in preterm, especially extremely-low-birth-weight neonates. An increased length of time to reach full enteral feedings is also significantly associated with a poorer mental outcome in preterm neonates at 24 months corrected age. Optimization of enteral nutrition without increasing the risk of necrotizing enterocolitis (NEC) has thus become a priority in preterm neonates. A range of feeding strategies currently exists for preventing/minimizing feed intolerance in preterm neonates reflecting the dilemma surrounding the definition and significance of signs of feed intolerance due to ileus of prematurity and the fear of NEC. The results of a systematic review of current strategies for preventing/minimizing feed intolerance in preterm neonates are discussed. The need for clinical research in the area of signs of feed intolerance is emphasized to develop a scientific basis to feeding strategies. Only large pragmatic trials based on such strategies will reveal whether the benefits (improved growth and long term neurodevelopmental outcomes) of aggressive enteral nutrition can outweigh the risks of a potentially devastating illness like NEC, and of prolonged parenteral nutrition in preterm neonates.

Gastrointestinal contrast studies in high-risk neonates with suspected necrotising enterocolitis--a note of caution

Upper gastrointestinal contrast studies are frequently performed in neonates to rule out conditions such as malrotation. Low osmolality water-soluble (LOWS) contrast media are currently considered safe for use in neonates. The clinical course of a neonate with suspected necrotising enterocolitis, who deteriorated significantly due to peritonitis following contrast study with LOWS, is reported. The possibility that LOWS contrast media may not always be safe in high-risk neonates is raised.

Prebiotic concept for infant nutrition

In the neonatal period, the intestine is colonised in a stepwise process that depends on mode of delivery, environmental factors, bacterial interactions, and the host itself resulting in a colonisation with a complex heterogeneous bacterial flora. Oligosaccharides have been identified as an important prebiotic factor of human milk As long as analogues of human milk oligosaccharides are not available now and in the near future it is aimed to resemble the prebiotic effect of human milk by oligosaccharides from available sources. In the present study in preterm infants, a mixture of 90% galacto-oligosaccharides and 10% fructo-oligosaccharides has been tested. The mixture of GOS/FOS was composed to mimic the molecule size distribution of human milk oligosaccharides. Microbiological analysis of the faces was performed before and 7, 14, and 28 days after start of supplementation and stool characteristics have been recorded. Maltodextrin was used as placebo and infants fed human milk have been used as reference. After a 28 days feeding period, the number of bifidobacteria of the group fed the oligosaccharide supplemented formula was in the upper range of the reference group whereas the numbers of the group fed the formula supplemented with the placebo were in the lower range of the reference group (placebo: 7.9 +/- 0.83 and GOS/FOS mixture: 10,0 +/- 2.05 log 10 CFU/g wet stool; reference (M +/- SD): 7.14-10.7 log 10 CFU/g wet stool). Stool characteristics in the group fed the supplemented formula were close to those found in the human milk fed infants. In summary, supplementation of a preterm formula with a mixture of galacto- and fructo-oligosaccharides has a stimulating effect on the growth of bifidobacteria in the intestine and results in more frequent produced and softer stools. Thus, prebiotic mixtures such like the studied oligosaccharide mixture might help in improving intestinal tolerance to enteral feeding in preterm infants.

Nursing the preterm surgical neonate

The preterm neonate's response to surgery manifests in all body systems. Necrotising Enterocolitis (NEC) is an acute gastro-intestinal emergency requiring surgical intervention. Severe NEC may require the removal of infarcted bowel. Examining the response to surgery in the preterm neonate with NEC offers nurses a rationale for their post-operative care. Both physiological and psychological responses need to be understood in the light of family centred care.