Absent or reversed end diastolic flow velocity in the umbilical artery and necrotizing enterocolitis

A systematic review and meta-analysis of the role of Doppler ultrasonography of the superior mesenteric artery in detecting neonates at risk of necrotizing enterocolitis

The role of postnatal Doppler measurements of the superior mesenteric artery (SMA) in detecting neonates at risk of necrotizing enterocolitis (NEC) remains uncertain; therefore, we systematically reviewed and meta-analyzed the existing evidence regarding the usefulness of SMA Doppler measurements in detecting neonates at risk for NEC. We used the Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines, and we included studies which reported the following Doppler ultrasonography indices: peak systolic velocity, end-diastolic velocity, time average mean velocity, differential velocity, pulsatility index (PI) and resistive index. Eight studies were eligible for inclusion in the meta-analysis. Evidence suggested that, during the first postnatal day, neonates who developed NEC had a significantly higher peak systolic velocity (mean difference of 2.65 cm/s (95% confidence interval [CI] 1.23, 4.06, overall effect Z=3.66, P<0.001)), higher PI (mean difference of 1.52 (95% CI 0.00, 3.04, Z=1.96, P=0.05)) and higher resistive index (mean difference of 1.09 (95% CI 0.59, 1.60, Z=4.24, P<0.001)), compared to neonates who did not develop NEC. However, our findings do not support a strong association between the Doppler ultrasound indices and development of NEC at the time of disease onset. This meta-analysis suggests that first postnatal day SMA Doppler parameters, namely peak systolic velocity, PI and resistive index, are higher in neonates who develop NEC. On the other hand, the aforementioned indices are of uncertain significance once the diagnosis of NEC has been established.

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.

ADEPT - Abnormal Doppler Enteral Prescription Trial

BACKGROUND

Pregnancies complicated by abnormal umbilical artery Doppler blood flow patterns often result in the baby being born both preterm and growth-restricted. These babies are at high risk of milk intolerance and necrotising enterocolitis, as well as post-natal growth failure, and there is no clinical consensus about how best to feed them. Policies of both early milk feeding and late milk feeding are widely used. This randomised controlled trial aims to determine whether a policy of early initiation of milk feeds is beneficial compared with late initiation. Optimising neonatal feeding for this group of babies may have long-term health implications and if either of these policies is shown to be beneficial it can be immediately adopted into clinical practice.

METHODS AND DESIGN

Babies with gestational age below 35 weeks, and with birth weight below 10th centile for gestational age, will be randomly allocated to an "early" or "late" enteral feeding regimen, commencing milk feeds on day 2 and day 6 after birth, respectively. Feeds will be gradually increased over 9-13 days (depending on gestational age) using a schedule derived from those used in hospitals in the Eastern and South Western Regions of England, based on surveys of feeding practice. Primary outcome measures are time to establish full enteral feeding and necrotising enterocolitis; secondary outcomes include sepsis and growth. The target sample size is 400 babies. This sample size is large enough to detect a clinically meaningful difference of 3 days in time to establish full enteral feeds between the two feeding policies, with 90% power and a 5% 2-sided significance level. Initial recruitment period was 24 months, subsequently extended to 38 months.

DISCUSSION

There is limited evidence from randomised controlled trials on which to base decisions regarding feeding policy in high risk preterm infants. This multicentre trial will help to guide clinical practice and may also provide pointers for future research.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN: 87351483.

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

BACKGROUND

Necrotizing enterocolitis (NEC) is the most common gastrointestinal (GI) emergency seen in neonatal units. Many factors have been considered as potentially important aetiologically, including gut ischaemia, sepsis and feeding. However, evidence remains equivocal.

OBJECTIVE

This study investigated whether preterm babies born to mothers with abnormal antenatal umbilical Dopplers (absent or reversed end diastolic flow--AREDF), that is exposed to antenatal gut ischaemia, are at an identical risk of developing NEC early in life, compared to babies born to mothers with normal Dopplers.

METHODS

All preterm (<or=32+6 week gestation) babies with no congenital anomaly, born to mothers resident in the county of Leicestershire in United Kingdom in 2001 and 2002 were identified using the Trent Neonatal Survey (TNS). Clinical data including the presence and severity of any NEC were extracted from the notes.

RESULTS

Two hundred forty-three preterm babies who met the criteria were identified during the period. Babies in whom umbilical Dopplers were not available and babies that died in the first 48 h were excluded. Complete data was thus available for 206 of these babies. A strong relation between AREDF and subsequent development of NEC was noted in these babies (OR: 5.88, 95% CI: 2.41 to 14.34, p<0.0001). This association still held after adjustment for gestational age at birth (OR: 7.64, 95% CI: 2.96 to 19.70, p<0.0001) and after adjustment for birthweight for gestational age z-score (OR: 6.72, 95% CI: 2.23 to 20.25, p=0.0007).

CONCLUSIONS

This study, based on a neonatal cohort, indicates that AREDF is an important independent risk factor for the production of NEC.

Management of preterm infants with intrauterine growth restriction

Preterm intrauterine growth restriction (IUGR) is strongly associated with increased mortality and morbidity. In the management of these infants, complications of preterm birth can be amplified by the effect of suboptimal fetal growth. It is important that pregnancies with IUGR are detected before birth, so that delivery can be arranged in a high-risk maternity unit with the appropriate neonatal staff in attendance. The provision of full support for resuscitation and stabilisation of these infants is crucial to the short-term and long-term health of these infants, who have suffered chronic hypoxia and malnutrition in utero. The long term outcome studies of these infants are retrospective and they include SGA infants. The effects of prematurity affect the outcome of IUGR infants. IUGR is associated with cerebral palsy in those delivered more than 32 weeks gestation. Infants less than 32 weeks of gestation may have poor developmental outcome if the head growth is affected, these infants may have associated cognitive and behavioural problems. Children who fail to grow by 2-4 years are at risk of long term growth problems. This paper outlines the acute and long-term management of these infants.

Feeding growth restricted preterm infants with abnormal antenatal Doppler results

Absence or reversal of end diastolic flow (AREDF) in the umbilical artery is associated with poor outcome, and elective premature delivery is common. Feeding these infants is a challenge. They often have poor tolerance of enteral feeding, and necrotising enterocolitis may develop. This review explores current practice to see if there is evidence on which to base guidelines. The incidence of necrotising enterocolitis is increased in infants with fetal AREDF, especially when complicated by fetal growth restriction. Abnormalities of splanchnic blood flow persist postnatally, with some recovery during the first week of life, providing justification for a delayed and careful introduction of enteral feeding. Such a policy exposes babies to the risks of parenteral nutrition, with no trials to date showing any benefit of delayed enteral nutrition. Trials are required to determine the optimum timing for introduction of enteral feeds in growth restricted infants with fetal AREDF.