A prolonged decline in the incidence of necrotizing enterocolitis after the introduction of a cautious feeding regimen

Standardizing feeding strategies for preterm infants born greater than 1500 grams

BACKGROUND

Use of standardized feeding protocols and donor breast milk (DBM) have been studied primarily in infants born <1500 g and not examined exclusively in infants born >1500 g.

METHODS

In this retrospective pre-post-implementation cohort study, we evaluated a protocol for preterm infants born >1500 g that was implemented clinically to standardize feeding advancements at 30 mL/kg/day, with infants born <33 weeks eligible to receive DBM. We compared placement of peripherally inserted central catheters for parenteral nutrition, feeding tolerance, growth, and maternal milk provision in the 18 months before/after implementation. The association between DBM intake and growth was evaluated using multivariable linear regression.

RESULTS

We identified 133 and 148 eligible infants pre/post-implementation. Frequency of peripherally inserted central catheters and rate of maternal milk provision was not statistically different. While there was no difference in median days to full enteral volume, there was a narrower distribution post-implementation (p < 0.001). Growth was similar between eras, but each 10% increase in DBM was associated with 1.0 g/d decrease in weight velocity (p < 0.001).

CONCLUSIONS

A feeding protocol for preterm infants >1500 g is associated with more consistent time to full enteral volume. Further investigation is needed to clarify DBM's impact on growth in this population.

IMPACT

Despite practice creep, no study has examined the use of standardized feeding protocols or pasteurized donor breast milk exclusively in infants >1500 g. A feeding protocol in this population may achieve full enteral feedings more consistently. With appropriate fortification, donor breast milk can support adequate growth in infants born >1500 g but warrants further study.

Standardizing Feeding Strategies in Moderately Preterm Infants

Objective

To evaluate the impact of a standardized feeding protocol and donor breast milk (DBM) provision on clinical outcomes in moderate preterm infants (MPT, 29-33 6/7 weeks gestational age).

Study Design

A protocol for MPT infants born > 1500 g was implemented clinically to standardize feeding advancements at 30 mL/kg/day. Infants < 33 weeks received DBM. We retrospectively identified 131 and 144 infants born before and after implementation. Clinical data including central venous line (CVL) placement, feeding tolerance, growth, and provision of maternal breast milk (MBM) were collected.

Result

Number of CVLs, days to full enteral volume (FEV), and MBM provision was unchanged. There was a narrower range of days to FEV post-implementation. Growth metrics were similar between eras.

Conclusion

Implementation of a feeding protocol for MPT infants is associated with more consistent time to FEV With monitoring and appropriate fortification, DBM use in this population is not associated with worse growth outcomes.

Standardized feeding regimen for reducing necrotizing enterocolitis in preterm infants: an updated systematic review

OBJECTIVE

A systematic review (2005) of observational studies has reported 87% reduction in the incidence of necrotizing enterocolitis (NEC) after introducing standardized feeding regimen (SFR) in preterm infants. Considering the many new studies in this field since 2005 and the continued health burden of NEC, we aimed to systematically review the incidence of NEC in preterm infants 'before' vs 'after' implementing a SFR.

STUDY DESIGN

PubMed, EMBASE, CINAHL and E-abstracts from the Pediatric Academic Society meetings and other pediatric and neonatal conference proceedings were searched in May 2016. Observational studies reporting incidence of NEC before and after implementing a SFR were included. Relevant data were extracted independently by two reviewers. Meta-analysis was conducted using random effects model (REM) and results rechecked with fixed effects model.

RESULTS

Pooled results from 15 observational studies (N=18 160) using REM showed that SFR significantly reduced the incidence of NEC (risk ratio 0.22; 95% confidence interval 0.13 to 0.36; P<0.00001; I2=74%). The results remained significant after comparing studies in two epochs (1978 to 2003 vs 2004 to 2016).

CONCLUSION

SFR continues to be an important tool in prevention of NEC in preterm infants.

Prevention of necrotising enterocolitis: Year 2004 and beyond

The incidence of necrotising enterocolitis (NEC) has not changed significantly despite the dramatic advances in perinatal-neonatal care. The absolute number of survivors of NEC is expected to rise, as prevention of prematurity, the single most important risk factor for the illness, continues to be difficult. Prevention of NEC has thus become an area of research priority. Given the role of inflammatory mediators in its pathogenesis newer immune modulators are being studied as potential agents for prevention/treatment of NEC. Caution, however, is warranted because the failure of sepsis trials in adults has clearly indicated that the concept of down-regulating the inflammatory response is deceptively simple. Clinical trials of any such promising preventative agent(s) need to be designed carefully and must include long-term neurodevelopmental outcomes as almost an entire population of high-risk preterm neonates will be exposed to their adverse effects. As new frontiers continue to be explored, the proven benefits of simple and safe interventions like antenatal glucocorticoid therapy and the preferential use of breast milk for feeding high-risk neonates must not be forgotten. Given that a single effective agent is unlikely in the near future, utilizing a package of "potentially better practices" seems to be the most appropriate strategy to prevent and minimize NEC.

Strategies for feeding the preterm infant

According to many experts in neonatal nutrition, the goal for nutrition of the preterm infant should be to achieve a postnatal growth rate approximating that of the normal fetus of the same gestational age. Unfortunately, most preterm infants, especially those born very preterm with extremely low birth weight, are not fed sufficient amounts of nutrients to produce normal fetal rates of growth and, as a result, end up growth-restricted during their hospital period after birth. Growth restriction is a significant problem, as numerous studies have shown definitively that undernutrition, especially of protein, at critical stages of development produces long-term short stature, organ growth failure, and both neuronal deficits of number and dendritic connections as well as later behavioral and cognitive outcomes. Furthermore, clinical follow-up studies have shown that among infants fed formulas, the nutrient content of the formula is directly and positively related to mental and motor outcomes later in life. Nutritional requirements do not stop at birth. Thus, delaying nutrition after birth 'until the infant is stable' ignores the fundamental point that without nutrition starting immediately after birth, the infant enters a catabolic condition, and catabolism does not contribute to normal development and growth. Oxygen is necessary for all metabolic processes. Recent trends to limit oxygen supply to prevent oxygen toxicity have the potential, particularly when the blood hemoglobin concentration falls to less than 8 g/dl, to develop growth failure. Glucose should be provided at 6-8 mg/min/kg as soon after birth as possible and adjusted according to frequent measurements of plasma glucose to achieve and maintain concentrations >45 mg/dl but <120 mg/dl to avoid the frequent problems of hyperglycemia and hypoglycemia. Similarly, lipid is required to provide at least 0.5 g/kg/day to prevent essential fatty acid deficiency. However, the high rate of carbohydrate and lipid supply that preterm infants often get, based on the incomplete assumption that this is necessary to promote protein growth, tends to produce increased fat in organs like the liver and heart as well as adipose tissue. More and better essential fatty acid nutrition is valuable, but more organ and adipose fat has no known benefit and many problems. Amino acids and protein are essential not only for body growth but for metabolic signaling, protein synthesis, and protein accretion. 3.5-4.0 g/kg/day are necessary to produce normal protein balance and growth in very preterm infants. Attempts to promote protein growth with insulin has many problems - it is ineffective while contributing to even further organ and adipose tissue fat deposition. Enteral feeding always is indicated and to date nearly all studies have shown that minimal enteral feeding approaches (e.g., 'trophic feeds') promote the capacity to feed enterally. Milk has distinct advantages over formulas in avoiding necrotizing enterocolitis (NEC), and while feeding is associated with NEC, minimal enteral feeding regimens produce less NEC than those geared towards more aggressive introduction of enteral feeding. Finally, overfeeding has the definite potential to produce adipose tissue, or obesity, which then leads to insulin resistance, glucose intolerance, and diabetes. This scenario occurs more commonly as infants are fed more and gain weight more rapidly after birth, regardless of their birth weight. Infants with IUGR and postnatal growth failure may be uniquely 'set up' for this outcome, while infants with in utero obesity, such as infants of diabetic mothers, already are well along this adverse outcome pathway.

Feeding strategies in the ELBW infant

Necrotizing enterocolitis (NEC) remains a common emergency that carries high morbidity and mortality for extremely low birth weight infants. To date there have been no multicenter randomized controlled trials to evaluate different feeding strategies and NEC. Clinicians must weigh their experience against small amounts of data in deciding the best way to feed their patients. Currently published feeding protocols and evidence for the same will be reviewed. Also reviewed is the evidence for use of human milk, initiation and advancement of feedings, and the use of probiotics.

Prevention of necrotizing enterocolitis in preterm infants: a 20-year experience

OBJECTIVE

Diet, indomethacin, and early use of dexamethasone have been implicated as possible causes of necrotizing enterocolitis and intestinal perforation. Because we seldom prescribe indomethacin or early dexamethasone therapy and we follow a special dietary regimen that provides late-onset, slow, continuous drip enteral feeding, we reviewed our 20 years of experience for the incidence of necrotizing enterocolitis and bowel perforation.

METHODS

We reviewed data on all 1239 very low birth weight infants (501-1500 g) admitted to our level III unit over a period of 20 years (1986-2005), for morphologic parameters, necrotizing enterocolitis, bowel perforation, use of the late-onset, slow, continuous drip protocol, and indomethacin therapy. Outcome data were also compared with Vermont Oxford Network data for the last 4 years.

RESULTS

In 20 years, 1158 infants received the late-onset, slow, continuous drip feeding protocol (group I), whereas 81 infants had either a change in dietary regimen, use of indomethacin, or early use of dexamethasone (group II). The rate of necrotizing enterocolitis in group I of 0.4% was significantly lower than that in group II of 6%. Group I, in comparison with the Vermont Oxford Network, had significantly lower rates of necrotizing enterocolitis (0.4% vs 5.9%), surgical necrotizing enterocolitis (0.4% vs 3.1%), and bowel perforation (0.35% vs 2.2%).

CONCLUSIONS

Our 20-year experience with 1239 very low birth weight infants suggests strongly that the late-onset, slow, continuous drip feeding protocol and avoidance of indomethacin and early dexamethasone treatment contribute to the prevention of necrotizing enterocolitis.

Early enteral feeding for the very low birth weight infant: the development and impact of a research-based guideline

Providing optimal nutrition for the very low birth weight (VLBW) infant is critical during the neonatal period. Evidence-based practice guidelines are essential in managing these fragile infants. Putting scientific research into daily clinical practice may be arduous at times, however. A multidisciplinary team of health care providers successfully established a practical feeding guideline for a 52-bed, teaching-affiliated, Level III neonatal intensive care unit in St. Louis. This guideline identifies human milk as the recommended source of nutrition for the VLBW infant, a suggestion that has significantly affected lactation services in the unit. This article describes the process of developing, implementing, and evaluating a feeding guideline based on current research and describes the impact on lactation rates of having such a guideline in place within the unit.

Impact of standardised feeding regimens on incidence of neonatal necrotising enterocolitis: a systematic review and meta-analysis of observational studies

BACKGROUND

A significant and prolonged decline in the incidence of necrotising enterocolitis (NEC), nearing virtual elimination in some centres, has been observed consistently since implementation of a standardised feeding regimen.

AIM

To systematically review the observational studies reporting incidence of NEC in preterm, low birth weight (LBW) neonates "before" and "after" implementation of a standardised feeding regimen.

METHODS

The Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 4, 2002), Medline, Embase, Cinahl, and proceedings of the Pediatric Academic Societies (published in Pediatric Research from 1980) were searched in July and again in October 2003. The reference lists of identified observational studies, and personal files, were searched. No language restriction was applied. Key words were: standardised, enteral, feeding, neonates, necrotising enterocolitis. Authors were contacted for clarification of data.

RESULTS

Six eligible studies (1978-2003) were identified. A significant heterogeneity was noted between the studies indicating the variations in the population characteristics and feeding practices over a period of 25 years. Meta-analysis of the six studies using a random effects model revealed a pooled risk ratio of 0.13 (95% confidence interval 0.03 to 0.50)-that is, introduction of a standardised feeding regimen reduced the incidence of NEC by 87%.

CONCLUSION

Standardised feeding regimens may provide the single most important global tool to prevent/minimise NEC in preterm neonates. Randomised controlled trials are needed.

Virtual elimination of necrotising enterocolitis for 5 years - reasons?

A standardised feeding regimen was adopted in 1997 for guiding enteral feeding of neonates <32 weeks' gestation during clinical trials (18 months each) involving erythromycin (n=73) as a prokinetic and carboxymethylcellulose (n=70) as a laxative as well as for during 2 years (n=155) without any trials. Most aspects of the feeding regimen (e.g., milk increments-total volume/day, use of breast milk by choice, etc) were not significantly different from current practices.

RESULTS

298 neonates <32 weeks' gestation (<28 weeks; n=78) were enterally fed during the 5 years. Their demographic characteristics and median (interquartile) age in days at starting (AST) and days to reach full enteral feeds (FFT) of 150 ml/kg/day were not significantly different during these 5 years: [AST: 5 (3-7.5)], [FFT: 4 (3-7)] Only one case of definite NEC (> or =Stage II) occurred during the 5 years. The time to reach full feeds was also reduced by over 54% (including for neonates <28 weeks gestation) compared with a historical cohort.

CONCLUSION

Sustained reduction in the time to reach full feeds with virtual elimination of > or =Stage II NEC for 5 years indicates continued benefits of a standardised feeding regimen as a simple preventive strategy to prevent NEC. Whether our specific policy of no enteral feeds in presence of hemodynamic instability associated with PDA requiring indomethacin, and/or sepsis played a role in achieving the significant results needs controlled trials.

Current controversies in the understanding of necrotizing enterocolitis. Part 1

Necrotizing enterocolitis (NEC) has widespread implications for neonates. While mostly affecting preterm neonates, full-term neonates, especially those with congenital heart disease, are also at risk. Although the exact pathogenesis of NEC remains elusive, three major factors, a pathogenic organism, enteral feedings, and bowel compromise, coalesce in at-risk neonates to produce bowel injury. Initiation of the inflammatory cascade likely serves as a common pathway for the disorder. Clinical signs and symptoms range from mild feeding intolerance with abdominal distension to catastrophic disease with bowel perforation, peritonitis, and cardiovascular collapse. Vigilant assessment of at-risk neonates is crucial. When conservative medical management fails to halt injury, surgical intervention is often needed. Strategies to decrease the incidence and ultimately prevent NEC loom on the horizon, such as exclusive use of human breastmilk for enteral feedings and administration of probiotics.

Epidemiology of neonatal necrotising enterocolitis: a population-based study

We examined the birthweight-, gender- and race-specific incidence as well as the biodemographic and clinical correlates of necrotising enterocolitis (NEC) in a well-defined six-county perinatal region in upstate New York. We conducted a retrospective, 8-year population-based survey to identify all cases of proven NEC (modified Bell stage II and above) in the area's regional neonatal intensive care unit (NICU). The denominator used to calculate the incidence was obtained from the Statewide Planning Research Cooperative System. Incidence was expressed as cases per 1000 live births. A total of 85 documented cases of proven NEC was identified in a six-county perinatal region that experienced 117 892 live births during the 8-year period. The average annual incidence was 0.72 cases per 1000 live births [95% CI 0.57, 0.87 per 1000 live births]. The highest incidence of NEC occurred among infants weighing 750-1000 g at birth and declined with increasing birthweight. The urban county had a 1.53 times higher risk of NEC than rural counties [95% CI 0.9, 2.6]. The overall incidence of NEC for non-Hispanic blacks was significantly greater than that for non- Hispanic whites (2.2 vs. 0.5 cases per 1000 live births, P = 0.00). The differences remained statistically significant even after correction for birthweight. Most cases (93%) in this series were preterm (gestational age <37 weeks). Only two patients were never fed before the diagnosis of NEC was confirmed. Positive blood cultures were documented in 27% of the cases with a predominance of Gram-negative enteric micro-organisms. NEC remains an important health problem especially for preterm infants and the non-Hispanic black population.

Evidence-based feeding guidelines for very low-birth-weight infants

Clinical practice guidelines (CPG) for the nutritional management of premature infants are limited. This project focused on the development of a research-based enteral feeding CPG for infants of < 1,500 g. The CPG was based on an extensive literature review and developed through a process of consensus decision making by a team of clinical researchers. Infants that weigh < 1,000 g initiate minimal enteral nutrition (MEN) at 48 hours; nutritional feedings begin on day 5 to 6 of life. For infants between 1,000 and 1,500 g, nutritional feedings begin at 48 hours and are advanced at a rate of less than 30 mL/kg per day. The benefits and risks of continuous versus intermittent nasogastric tube feeding were inconclusive; therefore, the CPG does not stipulate a feeding method. Breast milk is used preferentially, and specific guidelines for the definition and management of feeding intolerance are provided. A follow-up study testing this CPG has been completed and is published in the original research section of this issue.

The incidence of necrotizing enterocolitis after introducing standardized feeding schedules for infants between 1250 and 2500 grams and less than 35 weeks of gestation

OBJECTIVE

To evaluate the incidence of necrotizing enterocolitis (NEC) after implementing standardized feeding schedules.

METHOD

This was a cohort study, which retrospectively reviewed the incidence of NEC for a 3-year period before implementing feeding schedules and prospectively evaluated the incidence of NEC for a 3-year period after implementing feeding schedules in infants with birth weights between 1250 and 2500 g and <35 weeks' gestation. The feeding schedules were comprised of 3 parts. First, no group was fed within the first 24 hours of life. Feeds were started between 24 to 72 hours of life based on birth weight. Second, the initial feed was full-strength breast milk or half-strength formula. Half-strength formula was changed to full-strength formula on the fourth day for all groups. Third, the daily feeding volume increase was no greater than 20 mL/kg for all groups.

RESULTS

In the 477 infants before the feeding schedules, there were 23 (4.8%) cases of definite NEC defined as pneumatosis on abdominal film or NEC confirmed at the time of surgery, and in the 466 infants after the feeding schedules, there were 5 (1.1%) cases of NEC. Before the feeding schedules, those who developed NEC started feeds sooner 1.5 +/- 1.5 (+/- standard deviation [SD]) days versus 3.0 +/-.7 (+/-SD) days, reached full feeds sooner 4.0 +/- 1.8 (+/- SD) days versus 9.8 +/-.5 (+/-SD) days and were more likely to have been started on formula than those who developed NEC after implementing the feeding schedules. The mean time for NEC to occur after the feeding schedules increased from 5.9 +/- 4.1 (+/-SD) days to 19.4 +/- 16.3 (+/- SD) days, although not statistically significant. The number of mothers who received prenatal steroids increased after the feeding schedules. The number of infants with NEC, however, significantly decreased whether their mothers were pretreated with steroids. The risk of NEC was reduced 84% after the introduction of feeding schedules as determined by multiple logistic regression analysis and adjusting for confounding by birth weight, white race, prenatal steroid exposure, day of life of first feed, day of life to reach full feeds, and breast milk.

CONCLUSION

The incidence of NEC was significantly decreased after the implementation of standardized feeding schedules, which was independent of birth weight, prenatal steroid exposure, breast milk, day of life of first feed, and the number of days to reach full feeds.

Enteral feeding in the preterm infant

In planning enteral feeding in the preterm infant, decisions need to be made regarding the feeding schedule, choice of milk, and the route of administration. Feeds should be commenced within a week after birth beginning with subnutritional quantities. Preterm human milk from the infant's own mother is the milk of choice. When full enteral feeding is established, supplementation with human milk fortifier is recommended. Donor human milk and preterm formula are alternatives. Early establishment of enteral nutrition and maintenance of optimal nutrition during infancy are important as dietary manipulations in preterm infants have potential long-term influences on their health, growth and neurodevelopment.

Randomized trial of "slow" versus "fast" feed advancements on the incidence of necrotizing enterocolitis in very low birth weight infants

OBJECTIVE

To determine whether the rate of feed advancement affects the incidence of necrotizing enterocolitis (NEC).

STUDY DESIGN

Prospective randomized controlled trial involving 185 formula-fed infants with birth weight 501 to 1500 g and gestational age </=34 weeks. Infants were randomized into 2 groups: "slow" (n = 98), who received 15 cc/kg/d increments (a 10-day schedule to full feeds) and "fast" (n = 87), who received 35 cc/kg/d increments (a 5-day schedule to full feeds) of Similac Special Care 20 cal/oz. Feeds were increased only if well tolerated as defined by a protocol.

RESULTS

The incidence of NEC (Bell stage >/=II) was similar in both groups (slow 13% and fast 9%, P =.5). The incidence of perforation (Bell stage III) was also similar in both groups (slow 4% and fast 2%, P =.8). Feeds were started at a comparable postnatal age in both groups (median age: slow 5 days and fast 4 days, P =.9). Although the neonates in the fast group attained full enteral intake earlier (median days [25th and 75th percentiles]: slow 15 [12, 21] and fast 11 [8, 15], P <.001) and regained their birth weight earlier (slow 15 [11, 20] and fast 12 [8, 15], P <.05), their ages at discharge were not statistically different (slow 47 [31, 67] and fast 43 [29, 62], P =.3)

CONCLUSIONS

A greater than twofold difference in the rate of feed advancement from 15 cc/kg/d to 35 cc/kg/d did not affect the incidence of NEC >/= stage II. Factors other than feed advancement appear to be more important in the pathogenesis or progression of NEC.

Assessing the effect of disease on nutrition of the preterm infant

OBJECTIVE

To review existing data on nutritional requirements of extremely low birth weight (ELBW) and very low birth weight (VLBW) preterm infants (those who weigh < 1000 g and 1000-1500 g at birth, respectively), and the effects of diseases on these nutritional requirements.

DATA SOURCES

A literature search was conducted on applicable articles related to nutritional requirements of preterm ELBW and VLBW infants and the effects of diseases in these infants on their nutritional and metabolic requirements.

DATA SYNTHESIS

The literature was analyzed to determine nutritional requirements of preterm ELBW and VLBW infants, to select the most common diseases that have significant and important effects on nutrition and metabolism in these infants, and to make recommendations about diagnostic and therapeutic approaches to nutritional problems as affected by diseases in ELBW and VLBW infants.

CONCLUSIONS

Many diseases unique to preterm infants, either directly or by enhancing the effects of stress on the metabolism of such infants, provide important changes in the nutrient requirements. The overriding observation from all studies, however, is that ELBW and VLBW preterm infants are underfed during the early postnatal period and that this condition, combined with additional stresses from various diseases, increases the risk of long-term neurological sequelae. The value of achieving a specific body composition and growth weight is less certain. There remains a critical need for determining the right quality as well as quantity of nutrients for these infants.

Amino acid solutions for premature neonates during the first week of life: the role of N-acetyl-L-cysteine and N-acetyl-L-tyrosine

Tyrosine and cyst(e)ine are amino acids that are thought to be essential for preterm neonates. These amino acids have low stability (cyst(e)ine) or low solubility (tyrosine) and are therefore usually present only in small amounts in amino acid solutions. Acetylation improves the stability and solubility of amino acids, facilitating a higher concentration in the solution. We compared three commercially available amino acid solutions, Aminovenös-N-päd 10%, Vaminolact 6.5%, and Primène 10%, administered to 20 low-birth-weight neonates on total parenteral nutrition from postnatal day 2 onward. Aminovenös-N-päd 10% contains acetylated tyrosine and acetylated cysteine; the other solutions do not contain acetylated amino acids and differ in the amount of tyrosine and cysteine added. On postnatal day 7, plasma amino acids were measured together with urinary excretion of amino acids and the total nitrogen excretion; 38% of the intake of N-acetyl-L-tyrosine and 53% of the intake of N-acetyl-L-cysteine were excreted in urine. Plasma levels of N-acetyl-L-tyrosine (331 +/- 74 mumol/L) and N-acetyl-L-cysteine (18 +/- 29 mumol/L) were higher than those of tyrosine (105 +/- 108 mumol/L) and cystine (11 +/- 9 mumol/L), respectively. Plasma tyrosine levels in the groups receiving small amounts of tyrosine remained just below the reference range. We show a linear correlation of plasma cystine with the intake of cysteine (r = .75, p = 0.01), but not with N-acetyl-L-cysteine. The estimated intake of cysteine should be 500 mumol.kg-1.d-1 in order to obtain levels comparable with those shown in normal term, breast-fed neonates. Nitrogen retention did not differ among the three groups (247 to 273 mg.kg-1.d-1).(ABSTRACT TRUNCATED AT 250 WORDS)

Epidemiology of necrotizing enterocolitis

The descriptive epidemiology of necrotizing enterocolitis (NEC) is presented. Areas addressed include incidence, race, sex, age of onset, mortality rates, and endemic versus epidemic disease. Both descriptive and case control studies are reviewed to uncover clues relevant to the causes, pathogenesis, and prevention of NEC.