Antenatal umbilical Doppler abnormalities: an independent risk factor for early onset neonatal necrotizing enterocolitis in premature infants

Analysis of the duration of exclusive breastfeeding in premature infants and its influencing factors

PURPOSE

The purpose of this study was to investigate the duration of breastfeeding among preterm infants within the first 12 months after birth and analyzed factors influencing the duration of exclusive breastfeeding.

DESIGN AND METHODS

In this retrospective study, premature infants who were hospitalized in the Neonatal Intensive Care Unit (NICU) premature delivery area of a third-class maternal and child health hospital in Changsha City, Hunan Province, China from October 2020 to January 2021 were selected as the participants for this study. Relevant data of these infants during their hospitalization was obtained from the hospital information system, while the rate of exclusive breastfeeding among preterm infants at a corrected age of 12 months was tracked through telephone follow-up. Univariate analysis of the effects of breastfeeding duration in preterm infants was conducted based on Mann-Whitney U test and Kruskal-Wallis H test. Multiple linear regression was then applied to determine the factors influencing the duration of exclusive breastfeeding in preterm infants.

RESULTS

The median and interquartile range of breastfeeding duration for preterm infants in this study was 4.00 (1.00, 6.00) months. Multiple linear regression analysis showed that the duration of exclusive breastfeeding was affected by several factors including how much other family members support breastfeeding, whether the mother returns to work after maternal leave, and whether the infant is a twin (P < 0.05).

CONCLUSION

The duration of exclusive breastfeeding among preterm infants needs to be improved by strengthening health education regarding the benefits of breastfeeding for preterm infants. Medical staff should provide guidance, encourage continuous nursing after discharge, and work with the community to implement targeted intervention measures with the goal of increasing the duration of exclusive breastfeeding among premature infants.

IMPLICATIONS TO PRACTICE

Because breastfeeding is vitally important for premature infants, we should encourage longer breastfeeding duration for premature infants by increasing family support, removing barriers to workplace breastfeeding, enhancing people's confidence in breastfeeding and providing support to mothers with twins. Hopefully, these measure can promote breastfeeding for premature infants.

The Practice of Enteral Nutrition: Clinical Evidence for Feeding Protocols

Establishing full enteral nutrition in critically ill preterm infants with immature gastrointestinal function is challenging. In this article, we will summarize emerging clinical evidence from randomized clinical trials suggesting the feasibility and efficacy of feeding interventions targeting the early establishment of full enteral nutrition. We will also examine trial outcomes of higher volume feedings after the establishment of full enteral nutrition. Only data from randomized clinical trials will be discussed extensively. Future opportunities for clinical research will also be presented.

Impact of maternal factors, environmental factors, and race on necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a complex disease with a multifactorial etiology. As the leading cause of intestinal morbidity and mortality among premature infants, many resources are being dedicated to neonatal care and molecular targets in the newborn intestine. However, NEC is heavily influenced by maternal and perinatal factors as well. Given its nature, preventive approaches to NEC are more likely to improve outcomes than new treatment strategies. Therefore, this review focuses on maternal, environmental, and racial factors associated with the development of NEC, with an emphasis on those that may be modifiable to decrease the incidence of the disease.

Necrotizing Enterocolitis: The Role of Hypoxia, Gut Microbiome, and Microbial Metabolites

Necrotizing enterocolitis (NEC) is a life-threatening disease that predominantly affects very low birth weight preterm infants. Development of NEC in preterm infants is accompanied by high mortality. Surgical treatment of NEC can be complicated by short bowel syndrome, intestinal failure, parenteral nutrition-associated liver disease, and neurodevelopmental delay. Issues surrounding pathogenesis, prevention, and treatment of NEC remain unclear. This review summarizes data on prenatal risk factors for NEC, the role of pre-eclampsia, and intrauterine growth retardation in the pathogenesis of NEC. The role of hypoxia in NEC is discussed. Recent data on the role of the intestinal microbiome in the development of NEC, and features of the metabolome that can serve as potential biomarkers, are presented. The Pseudomonadota phylum is known to be associated with NEC in preterm neonates, and the role of other bacteria and their metabolites in NEC pathogenesis is also discussed. The most promising approaches for preventing and treating NEC are summarized.

Association between Abnormal Antenatal Doppler Characteristics and Gastrointestinal Outcomes in Preterm Infants

Antenatal Doppler disturbances are associated with fetal hypoxia and may induce a brain-sparing vascular redistribution at the expense of splanchnic circulation, possibly predisposing to gut complications. We aimed to compare several gastrointestinal outcomes among very-low-birthweight (VLBW) preterm infants with different antenatal Doppler features. VLBW infants born between 2010-2022 were retrospectively included and stratified into the following clusters based on antenatal Doppler characteristics: normal Doppler (controls); absent or reversed end-diastolic flow in the umbilical artery (UA-AREDF) alone or also in the ductus venosus (UA+DV-AREDF); and abnormal Doppler with or without brain-sparing redistribution. The following outcomes were evaluated: time to reach full enteral feeds (FEF), feeding intolerance (FI), necrotizing enterocolitis (NEC), and spontaneous intestinal perforation (SIP). Overall, 570 infants were included. Infants born following UA+DV-AREDF had significantly higher FI, NEC, and SIP rates and achieved FEF later compared to controls. Increased FI prevalence and a longer time to FEF compared to controls were also observed among UA-AREDF infants and in the presence of brain-sparing redistribution, which also increased NEC rates. Antenatal Doppler abnormalities exacerbate the gastrointestinal risks of preterm infants. Detailed knowledge of Doppler features can aid in identifying those at highest risk of intestinal complications who may benefit from tailored enteral feeding management.

Intestinal atresia and necrotizing enterocolitis: Embryology and anatomy

The primitive gut originates at week 3 of gestation from the endoderm, with posterior incorporation of the remaining embryo layers. Wnt, Notch and TLR4 pathways have been shown to play central roles in the correct development of the intestine. The classical hypothesis for intestinal atresia development consists of failure in bowel recanalization or a vascular accident with secondary bowel reabsorption. These have been challenged due to the high frequency of associated malformations, and furthermore, with the discovery of molecular pathways and genes involved in bowel formation and correlated defects producing atresia. Necrotizing enterocolitis (NEC) has a multifactorial pathogenesis with prematurity being the most important risk factor; therefore, bowel immaturity plays a central role in NEC. Some of the same molecular pathways involved in gut maturation have been found to correlate with the predisposition of the immature bowel to develop the pathological findings seen in NEC.

Delayed introduction of progressive enteral feeds to prevent necrotising enterocolitis in very low birth weight infants

BACKGROUND

Enteral feeding for very preterm or very low birth weight (VLBW) infants is often delayed for several days after birth due to concern that early introduction of feeding may not be tolerated and may increase the risk of necrotising enterocolitis. Concerns exist, however, that delaying enteral feeding may diminish the functional adaptation of the gastrointestinal tract and prolong the need for parenteral nutrition with its attendant infectious and metabolic risks.

OBJECTIVES

To determine the effects of delayed introduction of progressive enteral feeds on the risk of necrotising enterocolitis, mortality and other morbidities in very preterm or VLBW infants.

SEARCH METHODS

Search strategies were developed by an information specialist in consultation with the review authors. The following databases were searched in October 2021 without date or language restrictions: CENTRAL (2021, Issue 10), MEDLINE via OVID (1946 to October 2021), Embase via OVID (1974 to October 2021), Maternity and Infant Care via OVID (1971 to October 2021), CINAHL (1982 to October 2021). We also searched for eligible trials in clinical trials databases, conference proceedings, previous reviews, and reference lists of retrieved articles.

SELECTION CRITERIA

Randomised controlled trials that assessed the effects of delayed (four or more days after birth) versus earlier introduction of progressive enteral feeds on necrotising enterocolitis, mortality and other morbidities in very preterm or VLBW infants.

DATA COLLECTION AND ANALYSIS

Two review authors separately evaluated trial risk of bias, extracted data, and synthesised effect estimates using risk ratio (RR), risk difference (RD), and mean difference. We used the GRADE approach to assess the certainty of evidence for effects on necrotising enterocolitis, mortality,  feed intolerance, and invasive infection.

MAIN RESULTS

We included 14 trials in which a total of 1551 infants participated. Potential sources of bias were lack of clarity on methods to generate random sequences and conceal allocation in half of the trials, and lack of masking of caregivers or investigators in all of the trials. Trials typically defined delayed introduction of progressive enteral feeds as later than four to seven days after birth and early introduction as four days or fewer after birth. Infants in six trials (accounting for about half of all of the participants) had intrauterine growth restriction or circulatory redistribution demonstrated by absent or reversed end-diastolic flow velocities in the fetal aorta or umbilical artery.  Meta-analyses showed that delayed introduction of progressive enteral feeds may not reduce the risk of necrotising enterocolitis (RR 0.81, 95% confidence interval (CI) 0.58 to 1.14; RD -0.02, 95% CI -0.04 to 0.01; 13 trials, 1507 infants; low-certainty evidence due risk of bias and imprecision) nor all-cause mortality before hospital discharge (RR 0.97, 95% CI 0.70 to 1.36; RD -0.00, 95% CI -0.03 to 0.03; 12 trials, 1399 infants; low-certainty evidence due risk of bias and imprecision). Delayed introduction of progressive enteral feeds may slightly reduce the risk of feed intolerance (RR 0.81, 95% CI 0.68 to 0.97; RD -0.09, 95% CI -0.17 to -0.02; number needed to treat for an additional beneficial outcome = 11, 95% CI 6 to 50; 6 trials, 581 infants; low-certainty evidence due to risk of bias and imprecision) and probably increases the risk of invasive infection (RR 1.44, 95% CI 1.15 to 1.80; RD 0.10, 95% CI 0.04 to 0.15; number needed to treat for a harmful outcome = 10, 95% CI 7 to 25; 7 trials, 872 infants; moderate-certainty evidence due to risk of bias).  AUTHORS' CONCLUSIONS: Delaying the introduction of progressive enteral feeds beyond four days after birth (compared with earlier introduction) may not reduce the risk of necrotising enterocolitis or death in very preterm or VLBW infants. Delayed introduction may slightly reduce feed intolerance, and probably increases the risk of invasive infection.

Necrotizing enterocolitis: Bench to bedside approaches and advancing our understanding of disease pathogenesis

Necrotizing enterocolitis (NEC) is a devastating, multifactorial disease mainly affecting the intestine of premature infants. Recent discoveries have significantly enhanced our understanding of risk factors, as well as, cellular and genetic mechanisms of this complex disease. Despite these advancements, no essential, single risk factor, nor the mechanism by which each risk factor affects NEC has been elucidated. Nonetheless, recent research indicates that maternal factors, antibiotic exposure, feeding, hypoxia, and altered gut microbiota pose a threat to the underdeveloped immunity of preterm infants. Here we review predisposing factors, status of unwarranted immune responses, and microbial pathogenesis in NEC based on currently available scientific evidence. We additionally discuss novel techniques and models used to study NEC and how this research translates from the bench to the bedside into potential treatment strategies.

Potential Prenatal Origins of Necrotizing Enterocolitis

Necrotizing enterocolitis is a serious and yet incompletely understood gastrointestinal disease of infancy that predominately impacts premature neonates. Prevention is a key strategy for the management of necrotizing enterocolitis. Although postnatal risk factors have been the focus of prevention efforts, obstetric complications, including intrauterine inflammation and infection, growth restriction, preeclampsia, and prenatal medications, have been associated with an increased risk of necrotizing enterocolitis. This article reviews the evidence behind the prenatal risk factors for necrotizing enterocolitis, and discusses how these risk factors may elucidate the pathogenesis of necrotizing enterocolitis and provide insight into prevention and treatment.

Two speeds of increasing milk feeds for very preterm or very low-birthweight infants: the SIFT RCT

BACKGROUND

Observational data suggest that slowly advancing enteral feeds in preterm infants may reduce necrotising enterocolitis but increase late-onset sepsis. The Speed of Increasing milk Feeds Trial (SIFT) compared two rates of feed advancement.

OBJECTIVE

To determine if faster (30 ml/kg/day) or slower (18 ml/kg/day) daily feed increments improve survival without moderate or severe disability and other morbidities in very preterm or very low-birthweight infants.

DESIGN

This was a multicentre, two-arm, parallel-group, randomised controlled trial. Randomisation was via a web-hosted minimisation algorithm. It was not possible to safely and completely blind caregivers and parents.

SETTING

The setting was 55 UK neonatal units, from May 2013 to June 2015.

PARTICIPANTS

The participants were infants born at < 32 weeks' gestation or a weight of < 1500 g, who were receiving < 30 ml/kg/day of milk at trial enrolment.

INTERVENTIONS

When clinicians were ready to start advancing feed volumes, the infant was randomised to receive daily feed increments of either 30 ml/kg/day or 18 ml/kg/day. In total, 1400 infants were allocated to fast feeds and 1404 infants were allocated to slow feeds.

MAIN OUTCOME MEASURES

The primary outcome was survival without moderate or severe neurodevelopmental disability at 24 months of age, corrected for gestational age. The secondary outcomes were mortality; moderate or severe neurodevelopmental disability at 24 months corrected for gestational age; death before discharge home; microbiologically confirmed or clinically suspected late-onset sepsis; necrotising enterocolitis (Bell's stage 2 or 3); time taken to reach full milk feeds (tolerating 150 ml/kg/day for 3 consecutive days); growth from birth to discharge; duration of parenteral feeding; time in intensive care; duration of hospital stay; diagnosis of cerebral palsy by a doctor or other health professional; and individual components of the definition of moderate or severe neurodevelopmental disability.

RESULTS

The results showed that survival without moderate or severe neurodevelopmental disability at 24 months occurred in 802 out of 1224 (65.5%) infants allocated to faster increments and 848 out of 1246 (68.1%) infants allocated to slower increments (adjusted risk ratio 0.96, 95% confidence interval 0.92 to 1.01). There was no significant difference between groups in the risk of the individual components of the primary outcome or in the important hospital outcomes: late-onset sepsis (adjusted risk ratio 0.96, 95% confidence interval 0.86 to 1.07) or necrotising enterocolitis (adjusted risk ratio 0.88, 95% confidence interval 0.68 to 1.16). Cost-consequence analysis showed that the faster feed increment rate was less costly but also less effective than the slower rate in terms of achieving the primary outcome, so was therefore found to not be cost-effective. Four unexpected serious adverse events were reported, two in each group. None was assessed as being causally related to the intervention.

LIMITATIONS

The study could not be blinded, so care may have been affected by knowledge of allocation. Although well powered for comparisons of all infants, subgroup comparisons were underpowered.

CONCLUSIONS

No clear advantage was identified for the important outcomes in very preterm or very low-birthweight infants when milk feeds were advanced in daily volume increments of 30 ml/kg/day or 18 ml/kg/day. In terms of future work, the interaction of different milk types with increments merits further examination, as may different increments in infants at the extremes of gestation or birthweight.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN76463425.

FUNDING

This project was funded by the National Institute for Health Research Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 24, No. 18. See the NIHR Journals Library website for further project information.

Controlled Trial of Two Incremental Milk-Feeding Rates in Preterm Infants

BACKGROUND

Observational data have shown that slow advancement of enteral feeding volumes in preterm infants is associated with a reduced risk of necrotizing enterocolitis but an increased risk of late-onset sepsis. However, data from randomized trials are limited.

METHODS

We randomly assigned very preterm or very-low-birth-weight infants to daily milk increments of 30 ml per kilogram of body weight (faster increment) or 18 ml per kilogram (slower increment) until reaching full feeding volumes. The primary outcome was survival without moderate or severe neurodevelopmental disability at 24 months. Secondary outcomes included components of the primary outcome, confirmed or suspected late-onset sepsis, necrotizing enterocolitis, and cerebral palsy.

RESULTS

Among 2804 infants who underwent randomization, the primary outcome could be assessed in 1224 (87.4%) assigned to the faster increment and 1246 (88.7%) assigned to the slower increment. Survival without moderate or severe neurodevelopmental disability at 24 months occurred in 802 of 1224 infants (65.5%) assigned to the faster increment and 848 of 1246 (68.1%) assigned to the slower increment (adjusted risk ratio, 0.96; 95% confidence interval [CI], 0.92 to 1.01; P = 0.16). Late-onset sepsis occurred in 414 of 1389 infants (29.8%) in the faster-increment group and 434 of 1397 (31.1%) in the slower-increment group (adjusted risk ratio, 0.96; 95% CI, 0.86 to 1.07). Necrotizing enterocolitis occurred in 70 of 1394 infants (5.0%) in the faster-increment group and 78 of 1399 (5.6%) in the slower-increment group (adjusted risk ratio, 0.88; 95% CI, 0.68 to 1.16).

CONCLUSIONS

There was no significant difference in survival without moderate or severe neurodevelopmental disability at 24 months in very preterm or very-low-birth-weight infants with a strategy of advancing milk feeding volumes in daily increments of 30 ml per kilogram as compared with 18 ml per kilogram. (Funded by the Health Technology Assessment Programme of the National Institute for Health Research; SIFT Current Controlled Trials number, ISRCTN76463425.).

Maternal and placental risk factors associated with the development of necrotizing enterocolitis (NEC) and its severity

BACKGROUND/PURPOSE

Antenatal factors play an important role in NEC. This study aimed to identify antenatal risk factors associated with the development of NEC, the role of the placental alterations, and the presence of prenatal signs predisposing to a severe NEC.

MATERIALS/METHODS

Data of NEC patients including antenatal findings [preeclampsia, diabetes, cholestasis, abnormal antenatal umbilical artery flow (AAUF), clinical chorioamnionitis (CC), and histology of placentas] were compared to unaffected cases between 2002 and 2016 in a single center. Unaffected infants were matched for gestational age. Newborns with cardiovascular diseases were excluded. Bivariate and multivariate analyses were performed.

RESULTS

We identified 136 cases and 134 controls. The group of mothers of NEC-neonates had a higher prevalence of preeclampsia, CC, and AAUF. Histology of Placentas from 123/136 cases and 126/133 unaffected newborns was available. Chorioamnionitis was significantly more present in NEC cases vs controls. There weren't differences in vascular anomalies and necrotic alterations. Multivariate analysis identified AAUF, CC and histological chorioamnionitis (HC) as predictors of NEC. Bivariate tests show that preeclampsia and HC occurred more often in severe cases of NEC.

CONCLUSION

This study suggests that AAUF, CC, and HC can independently predict the risk of NEC. Preeclampsia and HC seem associated to more severe cases.

LEVEL OF EVIDENCE

IIIA.

Splanchnic NIRS monitoring in neonatal care: rationale, current applications and future perspectives

Near infrared spectroscopy (NIRS) provides a non-invasive, continuous monitoring of regional tissue oxygenation. NIRS assessment of neonatal splanchnic oxygenation (SrSO₂) has gained increasing interest over the last decade, as local hypoxia and ischemia underlie the most feared gut complications in neonates. Current literature provides encouraging evidence in support of SrSO₂ reliability in detecting mesenteric hemodynamic changes related to various physiological and pathological conditions in-term and preterm infants. Even so, while splanchnic NIRS monitoring looks promising for investigating gut physiopathology in research settings, further studies are needed to evaluate its feasibility as a routine monitoring tool in neonatal care and to investigate its potential role in clinical decision making. After a brief introduction to NIRS technical principles, this review aims to provide a complete overview of current neonatal applications for splanchnic NIRS monitoring, to discuss its possible limitations and to suggest future directions for research and clinical applications.

Early versus Late Enteral Feeding in Preterm Intrauterine Growth Restricted Neonates with Antenatal Doppler Abnormalities: An Open-Label Randomized Trial

BACKGROUND OF THE STUDY

Enteral feeding in preterm neonates with intrauterine growth restriction (IUGR) and absent or reversed end diastolic flow (AREDF) on umbilical artery (UA) Doppler is delayed owing to an increased risk of necrotizing enterocolitis (NEC). Delaying enteral feeding with longer duration of parenteral nutrition (PN) carries an increased risk of sepsis.

OBJECTIVES

To study early versus late feeding in preterm IUGR neonates for time required to attain sufficient feed volume to discontinue PN and increased risk of NEC or feed intolerance (FI).

DESIGN

Open-label randomized controlled trial.

SETTING

Tertiary care neonatal unit and fetal-maternal medicine unit in India.

PARTICIPANTS

Preterm intrauterine growth restricted neonates' ≤32 weeks with AREDF on UA Doppler enrolled from 1 January 2014 to 31 July 2015.

INTERVENTION

Randomized to receive early or late feeding using mothers own or donor breast milk as per a feed initiation and advancement protocol.

PRIMARY OUTCOME

Time in days required to attain sufficient feed volume allowing discontinuation of PN and incidence of NEC in neonates fed early versus late.

RESULTS

There were 77 eligible neonates. Sixty-two neonates were included and stratified as extreme preterm (27-29 weeks) (n = 20) and very preterm (30-32 weeks) (n = 42). Ten extreme preterm and 21 very preterm neonates were randomized to each early feeding and late feeding arm. There was a significantly faster attainment of sufficient feeds in the early feeding arm of both the stratified groups [extreme preterm: median 14 days (Interquartile range IQR: 12-15) compared with 18 days (IQR: 18-20), hazard ratio (HR): 1.59, 95% CI: 0.626-4.078; very preterm: 12 days (IQR: 10-14) as compared with 16 days (IQR 15-17), HR: 1.89, 95% CI: 1.011-3.555]. There was no difference in the incidence of NEC, FI and combined outcome of NEC and FI.

CONCLUSION

Early feeding in preterm IUGR neonates with AREDF on antenatal UA Doppler allowed earlier discontinuation of PN, allowing birth weight to be regained earlier and did not increase the incidence of NEC and FI.

The Speed of Increasing milk Feeds: a randomised controlled trial

Background

In the UK, 1–2% of infants are born very preterm (<32 weeks of gestation) or have very low birth weight (<1500 g). Very preterm infants are initially unable to be fed nutritional volumes of milk and therefore require intravenous nutrition. Milk feeding strategies influence several long and short term health outcomes including growth, survival, infection (associated with intravenous nutrition) and necrotising enterocolitis (NEC); with both infection and NEC being key predictive factors of long term disability. Currently there is no consistent strategy for feeding preterm infants across the UK. The SIFT trial will test two speeds of increasing milk feeds with the primary aim of determining effects on survival without moderate or severe neurodevelopmental disability at 24 months of age, corrected for prematurity. The trial will also examine many secondary outcomes including infection, NEC, time taken to reach full feeds and growth.

Methods/design

Two thousand eight hundred very preterm or very low birth weight infants will be recruited from approximately 30 hospitals across the UK to a randomised controlled trial. Infants with severe congenital anomaly or no realistic chance of survival will be excluded. Infants will be randomly allocated to either a faster (30 ml/kg/day) or slower (18 ml/kg/day) rate of increase in milk feeds. Data will be collected during the neonatal hospital stay on weight, infection rates, episodes of NEC, length of stay and time to reach full milk feeds. Long term health outcomes comprising vision, hearing, motor and cognitive impairment will be assessed at 24 months of age (corrected for prematurity) using a parent report questionnaire.

Discussion

Extensive searches have found no active or proposed studies investigating the rate of increasing milk feeds. The results of this trial will have importance for optimising incremental milk feeding for very preterm and/or very low birth weight infants. No additional resources will be required to implement an optimal feeding strategy, and therefore if successful, the trial results could rapidly be adopted across the NHS at low cost.

Trial registration

ISRCTN Registry; ISRCTN76463425 on 5 March, 2013.

Early feeding tolerance in small for gestational age infants with normal versus abnormal antenatal Doppler characteristics

OBJECTIVES

To determine differences in feeding tolerance amongst preterm small for gestational age (SGA) infants with normal versus abnormal umbilical artery Doppler flow defined as absent or reversed end diastolic flow (AREDF).

METHODS

This was a retrospective cohort study of infants <35 weeks gestational age (GA) and birth weight (BW) <10th percentile. Day of initiation of feeds, days to full feeds and CRIB II scores were the primary outcomes. Clinical characteristics were compared between the groups of SGA infants with normal and AREDF. Multivariable regression models were fit to the data to adjust for potential confounders of the association of AREDF and feeding intolerance.

RESULTS

120 infants with normal and 64 infants with AREDF were included. The infants with AREDF were smaller (971 g vs. 1183 g, p = 0.0002), less mature (29.9 wks vs. 31.2 wks, p = 0.0009), had higher CRIB II score (7.2 vs. 5.2, p = 0.0033), started feeding later (4.1 days vs. 3.3 days, p = 0.020) and advanced slower to full feeds (17.7 days vs. 13.7 days, p = 0.0017). Necrotizing enterocolitis was similar between the groups (p = 0.18). After adjusting for confounders, Doppler flow was no longer a significant predictor of the initiation (p = 0.37) and advancement of feeds (p = 0.44).

CONCLUSIONS

Infants with AREDF are sicker at birth and have more feeding difficulties; after adjusting for BW and GA, Doppler flow was no longer a significant predictor of feeding intolerance.

Slow versus rapid enteral feed in preterm neonates with antenatal absent end diastolic flow

OBJECTIVE

Incidence of feed intolerance (FI) and necrotizing enterocolitis (NEC) in preterm neonates with Doppler evidence of absent end diastolic flow (AEDF) velocities in the fetal umbilical artery when enteral feed volumes were started by 6-72 h and advanced either slowly or rapidly.

METHODS

Stable inborn neonates, 30-36 weeks gestation, weighing ≥1000 g and with antenatal evidence of AEDF were included in this pilot study. Infants (stratified in <1250 g and ≥1250 g birth weight categories) were allocated under randomized controlled trial, to receive either slow or rapid advancement of enteral feeding, while initiating the feeds after 6 h of birth if bowel sounds were present. Primary outcome measure was, FI and NEC till day 7 after reaching full feeds.

RESULTS

Of 159 eligible infants, 83 were randomized: 53 infants in the ≥1250 g category (28 in rapid and 25 in slow group) and 30 in the <1250 g category (15 in each group). FI was present in 11% versus 16% in ≥1250 g (p = 0.570) and 27% versus 33% in <1250 g (p = 0.690), NEC developed in 8.4% (3 versus 1) in ≥1250 g and (1 versus 2) in <1250 g, in slow versus rapid feeding.

CONCLUSION

This trial did not find increase in incidence of feed intolerance with very early introduction and rapid advancement of enteral feeds in stable preterm neonates with AEDF and birth weight ≥1250 g.

Foetal Doppler abnormality is associated with increased risk of sepsis and necrotising enterocolitis in preterm infants

AIM

Fetoplacental Doppler abnormalities have been associated with increased neonatal mortality and morbidity. This study evaluated the associations between prenatal Doppler assessments and neonatal mortality and morbidity in premature infants born small for gestational age or after pre-eclampsia.

METHODS

This was a population-based study of infants born alive at 22(0) -33(6) weeks of gestation, a birthweight <10th percentile for gestational age and/or maternal pre-eclampsia. Doppler assessments of the umbilical artery, middle cerebral artery and ductus venosus were evaluated in 127, 125 and 95 cases, respectively. Circulatory compromise was defined as absent or reversed end-diastolic velocity in the umbilical artery (AREDF), middle cerebral artery pulsatility index <2.5 percentile for gestational age and ductus venosus pulsatility index for veins >97.5 percentile.

RESULTS

AREDF was present in 28% of the infants. This was associated with increased frequencies of neonatal sepsis and necrotising enterocolitis after adjusting for gestational age. Abnormal ductus venosus pulsatility index for veins was associated with increased risk of neonatal sepsis, but only in combination with AREDF. These associations were only present when gestational age was <28 weeks.

CONCLUSION

AREDF was associated with increased neonatal morbidity in premature infants born small for gestational age or after pre-eclampsia.

Maternal risk factors for neonatal necrotizing enterocolitis

OBJECTIVE

This study aimed to investigate the relationship between maternal hypertensive disease and other risk factors and the neonatal development of necrotizing enterocolitis (NEC).

METHODS

This was a retrospective case-control study of infants with NEC from 2008 to 2012. The primary exposure of interest was maternal hypertensive disease, which has been hypothesized to put infants at risk for NEC. Other variables collected included demographics, pregnancy complications, medications and neonatal hospital course. Data were abstracted from medical records.

RESULTS

Twenty-eight cases of singleton neonates with NEC and 81 matched controls were identified and analyzed. There was no significant difference in the primary outcome. Fetuses with an antenatal diagnosis of growth restriction were more likely to develop NEC (p = 0.008). Infants with NEC had lower median birth weight than infants without NEC (p = 0.009). Infants with NEC had more late-onset sepsis (p = 0.01) and mortality before discharge (p = 0.001).

CONCLUSIONS

The factors identified by this case-control study that increased the risk of neonatal NEC included intrauterine growth restriction and lower neonatal birth weight. The primary exposure, hypertensive disease, did not show a significantly increased risk of neonatal NEC; however, there was a nearly two-fold difference observed. Our study was underpowered to detect the observed difference.

Prevention and early recognition of necrotizing enterocolitis: a tale of 2 tools--eNEC and GutCheckNEC

BACKGROUND AND SIGNIFICANCE

Risk for neonatal necrotizing enterocolitis (NEC) is complex, reflecting its multifactorial pathogenesis.

PURPOSE

To improve risk awareness and facilitate communication among neonatal caregivers, especially nurses, 2 tools were developed.

DESIGN

GutCheck was derived and validated as part of a formal research study over 3 phases, evidence synthesis, expert consensus building, and statistical modeling. The Wetzel/Krisman tool, eNEC, was developed and tested as part of a quality improvement initiative in a single clinical setting using evidence synthesis, review by internal expert clinicians, and implementation and evaluation of its use by direct line neonatal staff. Refinement of both tools is under way to evaluate their effect on clinical decision making, early identification of NEC and surgical NEC.

METHODS AND MAIN OUTCOMES

Clinicians can take an active role to reduce NEC in their units by focusing on modifiable risk factors such as adoption of standardized feeding protocols, preferential feeding of human milk, and antibiotic and histamine blocker stewardship.

RESULTS

Feeding during transfusion remains controversial, but judicious use of transfusions, adoption of transfusion guidelines, and withholding feeding during transfusion are feasible measures with potential benefit to prevent NEC and confer little risk.

Delayed introduction of progressive enteral feeds to prevent necrotising enterocolitis in very low birth weight infants

BACKGROUND

The introduction of enteral feeds for very preterm (less than 32 weeks' gestation) or very low birth weight (VLBW; less than 1500 g) infants is often delayed for several days or longer after birth due to concern that early introduction may not be tolerated and may increase the risk of necrotising enterocolitis (NEC). However, delaying enteral feeding could diminish the functional adaptation of the gastrointestinal tract and prolong the need for parenteral nutrition with its attendant infectious and metabolic risks.

OBJECTIVES

To determine the effect of delayed introduction of progressive enteral feeds on the incidence of NEC, mortality and other morbidities in very preterm or VLBW infants.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL, 2014, Issue 8), MEDLINE (1966 to September 2014), EMBASE (1980 to September 2014), CINAHL (1982 to September 2014), conference proceedings and previous reviews.

SELECTION CRITERIA

We included randomised or quasi-randomised controlled trials that assessed the effect of delayed (more than four days after birth) versus earlier introduction of progressive enteral feeds on the incidence of NEC, mortality and other morbidities in very preterm or VLBW infants.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial eligibility and risk of bias and undertook data extraction. We analysed the treatment effects in the individual trials and reported the risk ratio (RR) and risk difference for dichotomous data and mean difference for continuous data, with respective 95% confidence intervals (CI). We used a fixed-effect model in meta-analyses and explored the potential causes of heterogeneity in sensitivity analyses.

MAIN RESULTS

We identified nine randomised controlled trials in which 1106 infants participated. Few participants were extremely preterm (less 28 weeks' gestation) or extremely low birth weight (less than 1000 g). The trials defined delayed introduction of progressive enteral feeds as later than four to seven days after birth and early introduction as four days or less after birth. Meta-analyses did not detect statistically significant effects on the risk of NEC (typical RR 0.93, 95% CI 0.64 to 1.34; 8 trials; 1092 infants) or all-cause mortality (typical RR 1.18, 95% CI 0.75 to 1.88; 7 trials; 967 infants). Four of the trials restricted participation to growth-restricted infants with Doppler ultrasound evidence of abnormal fetal circulatory distribution or flow. Planned subgroup analyses of these trials found no statistically significant effects on the risk of NEC or all-cause mortality. Infants who had delayed introduction of enteral feeds took longer to establish full enteral feeding (reported median differences two to four days).

AUTHORS' CONCLUSIONS

The evidence available from randomised controlled trials suggested that delaying the introduction of progressive enteral feeds beyond four days after birth did not reduce the risk of developing NEC in very preterm or VLBW infants, including growth-restricted infants. Delaying the introduction of progressive enteral feeds resulted in a few days' delay in establishing full enteral feeds but the clinical importance of this effect was unclear. The applicability of these findings to extremely preterm or extremely low birth weight was uncertain. Further randomised controlled trials in this population may be warranted.

Risk of necrotizing enterocolitis and feeding interventions for preterm infants with abnormal umbilical artery Doppler

Infants exposed to absent or reversed end-diastolic flow (ARE DF) in utero may be at an increased risk of developing necrotizing enterocolitis (NEC). This article reviews placental function and the development of ARE DF. Studies examining the relationship between AREDF and NEC are reviewed, yet research remains inconclusive regarding this relationship. Recent studies reveal that early minimal enteral feeding does not increase the incidence of NEC in infants with AREDF. Initiation and advancement of enteral feedings should be monitored closely in this subset of the neonatal intensive care unit (NICU) population.

[Mesenteric flow in an experimental model of ischaemia-reperfusion in rats]

INTRODUCTION

Maintained acute occlusion followed by reperfusion of the superior mesenteric artery (SMA) in a few hours can trigger irreversible bowel damage. The aim of the study was to determine the changes in mesenteric flow measured by colour Doppler Ultrasound and correlating with histological lesions in an experimental model of ischaemia-reperfusion.

METHOD AND MATERIAL

Three groups of Sprague-Dawley 17 day-old rats were studied (control, ischemia and reperfusion). The model used was ischaemia-reperfusion over the SMA. Intra-abdominal ultrasound was then performed. The parameters recorded were: Maximum systolic velocity (MSV), pulsatility index (PI), resistance (RI) and systole-diastole (S/D). The histological variables were: intestinal lesion (Wallace/Keenan-Chiu scale), morphometrics (mean villus height [MVH]), and goblet cells. The Spearman (rs) correlation was used.

RESULTS

The MSV in the reperfusion group was 74.3 cm/s, the PI 7.33 and S/D 25.75 in the SMA, which were higher than the controls (41.35 cm/s; 3.12 and 12.45, respectively). A direct association (P<.01) was found between MSV, PI and S/D regarding: Wallace/Kennan scoring system (rs = 0.655; rs = 0.593; rs = 0.63) and the Chiu (rs = 0.569; rs = 0.522; rs = 0.47). While the correlation was the reverse (P<.01) when associated with the MVH (rs = -0,495; rs = -0,452; rs = -0,459) and goblet cells of the colon (rs = -0,525; rs = -0,45; rs = -0,518).

CONCLUSIONS

The reperfusion phase increased mesenteric flow expressed by the MSV and PI and could significantly predict the potential bowel damage at macroscopic and microscopic level.

Delayed introduction of progressive enteral feeds to prevent necrotising enterocolitis in very low birth weight infants

BACKGROUND

The introduction of enteral feeds for very preterm (< 32 weeks) or very low birth weight (< 1500 g) infants is often delayed for several days or longer after birth due to concern that early introduction may not be tolerated and may increase the risk of necrotising enterocolitis (NEC). However, delaying enteral feeding could diminish the functional adaptation of the gastrointestinal tract and prolong the need for parenteral nutrition with its attendant infectious and metabolic risks.

OBJECTIVES

To determine the effect of delayed introduction of progressive enteral feeds on the incidence of necrotising enterocolitis, mortality and other morbidities in very preterm or very low birth weight infants.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, 2013, Issue 3), MEDLINE (1966 to April 2013), EMBASE (1980 to April 2013), CINAHL (1982 to April 2013), conference proceedings, and previous reviews.

SELECTION CRITERIA

Randomised or quasi-randomised controlled trials that assessed the effect of delayed (more than four days after birth) versus earlier introduction of progressive enteral feeds on the incidence of NEC, mortality and other morbidities in very preterm or very low birth weight infants.

DATA COLLECTION AND ANALYSIS

We extracted data using the standard methods of the Cochrane Neonatal Review Group, with separate evaluation of trial quality and data extraction by two review authors.

MAIN RESULTS

We identified seven randomised controlled trials in which a total of 964 infants participated. Few participants were extremely preterm (< 28 weeks) or extremely low birth weight (< 1000 g). The trials defined delayed introduction as later than five to seven days after birth and early introduction as less than four days after birth. Meta-analyses did not detect statistically significant effects on the risk of NEC (typical risk ratio (RR) 0.92 (95% confidence interval (CI) 0.64 to 1.34) or all-cause mortality (typical RR 1.26 (95% CI 0.78 to 2.01)). Three of the trials restricted participation to growth-restricted infants with Doppler ultrasound evidence of abnormal fetal circulatory distribution or flow. Planned subgroup analyses of these trials did not find any statistically significant effects on the risk of NEC or all-cause mortality. Infants who had delayed introduction of enteral feeds took longer to establish full enteral feeding (reported median difference two to four days).

AUTHORS' CONCLUSIONS

The evidence available from randomised controlled trials suggests that delaying the introduction of progressive enteral feeds beyond four days after birth does not affect the risk of developing NEC in very preterm or very low birth weight infants, including growth-restricted infants. Delaying the introduction of progressive enteral feeds results in a few days delay in establishing full enteral feeds but the clinical importance of this effect is unclear. The applicability of these findings to extremely preterm or extremely low birth weight is uncertain. Further randomised controlled trials in this population may be warranted.

How to feed small for gestational age newborns

Feeding small for gestational age (SGA) newborns is extremely challenging and the neonatologist should be brave and cautious at the same time. Although these babies have a high risk of milk intolerance and necrotising enterocolitis, enteral feeding guidelines are not well established and practice varies widely among different neonatal units. Currently available studies on this topic include extremely and very low birth weight neonates, but are not focused specifically on small for gestational age infants. This review analyzes papers focused on feeding interventions in order to provide the best available evidences about the optimum timing for introduction of enteral feeding, how fast feed volume can be advanced, which milk and which feeding method is more appropriate in SGA infants.

Foetal umbilical artery Doppler in small preterms: (IQ) neurocognitive outcome at 5 years of age

AIM

To investigate whether absent or reversed end-diastolic flow in the umbilical artery (AREDF) is associated with neonatal mortality, morbidity or long-term neurocognitive outcome in extremely preterm infants exposed to preeclampsia or intrauterine growth restriction.

METHODS

Prenatal Doppler data were retrospectively collected for liveborn infants with gestational age (GA) <28 weeks or birth weight (BW) <1000 g, born small for gestational age (SGA- BW <5th percentile for GA) or of mothers with preeclampsia at the four largest university hospitals in Norway during 1999-2000. Neonatal mortality and morbidities, cerebral palsy (CP) and IQ at 5 years of age were compared for infants with or without AREDF.

RESULTS

Of 260 infants, 84 were eligible and 71 of them had sufficient Doppler data. Of these, 38 (54%) had AREDF. Of 33 infants born <28 weeks, 7 of 19 (37%) with AREDF and none of 14 without AREDF had severe cerebral haemorrhage (SCH) (p = 0.01). AREDF was not significantly associated with mortality, other NICU morbidities, CP or reduced IQ. For the 38 infants with GA ≥28 weeks, AREDF (19 of 38) was not associated with adverse outcomes.

CONCLUSION

Absent or reversed end-diastolic flow in the umbilical artery (AREDF) was associated with increased risk of SCH in extremely preterm infants (GA <28 weeks).

Biomarkers for prediction and diagnosis of necrotizing enterocolitis

This article summarizes the commonly used biomarkers currently available for diagnosis of necrotizing enterocolitis. The most exciting advances in diagnostic tests were the use of new nucleic acid sequencing techniques (eg, next-generation sequencing) and molecular screening methods (eg, proteomics and microarray analysis) for the discovery of novel biomarkers. The new technology platform coupled with stringent protocols of biomarker discovery and validation would enable neonatologists to study biologic systems at a level never before possible and discover unique biomarkers for specific organ injury and/or disease entity.

Necrotizing enterocolitis and the placenta - a key etiological link

AIM

Necrotizing enterocolitis (NEC) is the most common and severe acquired acute neonatal surgical condition, associated with premature neonates. Antenatal factors (e.g. vascular insufficiency and antenatal infections) may be important factors in "priming" the inflammatory cascade, thus predisposing to the disease. This study explores the role of placental pathology in predisposing to NEC pathogenesis.

METHODS

5338 placentas of high risk pregnancies were evaluated for placental insufficiency, infarction, and evidence of antenatal infection. Placentas of 72 premature infants developing surgical NEC (2007-2011) were identified as a separate study group and pathological placental features compared with unaffected infants.

RESULTS

Placentas of 72 of the 134 infants with surgically treated NEC (>grade 2 Bells) were available for pathologic evaluation (the remainder having been referred from other delivery units). Placentas of surgical NEC cases had significantly more evidence of noteworthy vascular pathology (placental infarcts) than high risk cases [n=38 (54.5%) versus n=1122 (21%); P<0.01]. Evidence of placental infection/chorioamnionitis or villitis plus evidence of foetal inflammatory response was present in surgical NEC infants versus unaffected infants [n=22 (31.8%) versus n=647 (12%); P<0.01], suggesting a possible pathogenic role.

CONCLUSION

This study suggests that exposure to antenatal placental infection may contribute to pathogenesis of NEC by modifying foetal vascular response and warrants further study.

Maternal preeclampsia is associated with increased risk of necrotizing enterocolitis in preterm infants

BACKGROUND

Necrotizing enterocolitis (NEC) is an important cause of mortality and morbidity in preterm infants.

AIMS

To evaluate the effect of maternal preeclampsia on the development and severity of NEC in premature infants.

STUDY DESIGN

Prospective observational study in a tertiary neonatal intensive care unit.

SUBJECTS

The preterm infants of ≤ 37 gestational age who were consecutively hospitalized were enrolled. The study group contained preterm infants born to a preeclamptic mother and the comparison group contained preterm infants born to a normotensive mother.

OUTCOME MEASURES

The primary outcome was to determine the association between preeclampsia and NEC.

RESULTS

A total of 88 infants had NEC diagnosis. The incidence of NEC in infants born to preeclamptic mothers (22.9%) was significantly higher compared with those born to normotensive mothers (14.6%). According to NEC stages, NEC was more advanced in preeclamptic mother infants. NEC developed significantly earlier in infants with NEC in the study group. The duration of NEC was also significantly longer in infants born to preeclamptic mothers. In multiple logistic regression model, preeclampsia was found to be predictive of NEC with an odds ratio of 1.74 (95% confidence interval 0.64-0.92).

CONCLUSIONS

Maternal preeclampsia may be an important risk factor for the development of NEC in premature infants as NEC incidence and severity of NEC were found to be significantly higher in premature infants born to preeclamptic mothers. The onset of NEC was significantly earlier and duration of NEC was longer in these infants.

Necrotizing enterocolitis risk: state of the science

Necrotizing enterocolitis (NEC) is the most common cause of gastrointestinal-related morbidity and mortality in the neonatal intensive care unit (NICU). Its onset is sudden and the smallest, most premature infants are the most vulnerable. Necrotizing enterocolitis is a costly disease, accounting for nearly 20% of NICU costs annually. Necrotizing enterocolitis survivors requiring surgery often stay in the NICU more than 90 days and are among those most likely to stay more than 6 months. Significant variations exist in the incidence across regions and units. Although the only consistent independent predictors for NEC remain prematurity and formula feeding, others exist that could increase risk when combined. Awareness of NEC risk factors and adopting practices to reduce NEC risk, including human milk feeding, the use of feeding guidelines, and probiotics, have been shown to reduce the incidence of NEC. The purpose of this review is to examine the state of the science on NEC risk factors and make recommendations for practice and research.

Pathogenesis and prevention of necrotizing enterocolitis

PURPOSE OF REVIEW

Necrotizing enterocolitis (NEC) remains the most common serious acquired gastrointestinal disorder affecting preterm infants. Here we review recent advances in our understanding of the pathogenesis of this multifactorial condition and consider the implications for practice and research.

RECENT FINDINGS

NEC is an important cause of mortality and serious morbidity in preterm infants. The risk is inversely proportional to gestational age and weight at birth. Fetal growth restriction and compromise may be additional specific risk factors. NEC, particularly severe NEC requiring surgical intervention and NEC with invasive infection, is associated with acute morbidity and mortality and adverse neurodevelopmental outcomes. The principal modifiable postnatal risk factors for NEC in preterm infants relate to enteral feeding practices including formula milk feeding, early and rapid advancement of enteral feed volumes, and exposure to H2-receptor antagonists.

SUMMARY

Our understanding of the pathogenesis of this condition remains incomplete. With the exception of feeding with human milk, only limited evidence is currently available to support interventions to prevent NEC. Promising strategies that merit further evaluation in randomized controlled trials include the use of prebiotics and probiotics and the avoidance of exposure to H2-receptor antagonists.

Delayed introduction of progressive enteral feeds to prevent necrotising enterocolitis in very low birth weight infants

BACKGROUND

The introduction of progressive enteral feeds for very low birth weight (VLBW) infants is often delayed for several days or longer after birth due to concern that earlier introduction may not be tolerated and may increase the risk of necrotising enterocolitis (NEC). However, delaying enteral feeding could diminish the functional adaptation of the gastrointestinal tract and prolong the need for parenteral nutrition with its attendant infectious and metabolic risks.

OBJECTIVES

To determine the effect of delayed introduction of progressive enteral feeds on the incidence of NEC, mortality and other morbidities in VLBW infants.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, 2010, Issue 4), MEDLINE (1966 to December 2010), EMBASE (1980 to December 2010), CINAHL (1982 to December 2010), conference proceedings, and previous reviews.

SELECTION CRITERIA

Randomised or quasi-randomised controlled trials that assessed the effect of delayed (more than four days' postnatal age) versus earlier introduction of progressive enteral feeds on the incidence of NEC, mortality and other morbidities in VLBW infants.

DATA COLLECTION AND ANALYSIS

Data collection and analysis were performed in accordance with the standard methods of the Cochrane Neonatal Review Group.

MAIN RESULTS

We identified five randomised controlled trials (RCT) in which a total of 600 infants participated. The trials defined delayed introduction as later than five to seven days after birth and early introduction as less than four days after birth. Two of the trials, in which a total of 488 infants participated, only recruited growth-restricted infants with Doppler ultrasound evidence of abnormal fetal circulatory distribution or flow. Meta-analyses did not detect statistically significant effects on the risk of NEC [typical relative risk 0.89, 95% confidence interval (CI) 0.58 to 1.37] or all cause mortality (typical relative risk 0.93, 95% CI 0.53 to 1.64). Infants who had delayed introduction of enteral feeds took significantly longer to establish full enteral feeding (reported median difference three days).

AUTHORS' CONCLUSIONS

Current trial data do not provide evidence that delayed introduction of progressive enteral feeds reduces the risk of NEC in VLBW infants. Delaying the introducing of progressive enteral feeds results in several days delay in establishing full enteral feeds but the clinical importance of this effect is unclear. Further RCTs are needed to give more precise estimates of the effect of delaying the introduction of enteral feeds on clinical outcomes in VLBW infants.

Placental vascular obstructive lesions: risk factor for developing necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a severe neonatal disease affecting particularly preterm infants. Its exact pathogenesis still remains unknown. In this study, we have compared the prevalence of vascular obstructive lesions in placentae of premature newborns which developed NEC and of a control group. We further compared separately the findings of placentae of infants of less than 30 weeks of gestation, the age group in which NEC occurs most frequently. We found signs of fetal vascular obstructive lesions in 65% of the placentae of preterm patients developing NEC, compared to only 17% of the placentae of preterm patients in the control group. In the age groups below 30 weeks of gestation, 58.5% of placentae of later NEC patients presented such lesions compared to 24.5% in the control group. The significant difference between NEC and control group suggests a strong association between fetal vascular obstructive lesions and NEC. Therefore, we propose that fetal vascular obstructive lesions might be considered as a risk factor for the development of NEC in premature infants.