Neurodevelopmental outcomes of very low-birth-weight infants after enteral glutamine supplementation in the neonatal period

The influence of very preterm birth on adolescent EEG connectivity, network organization and long-term outcome

OBJECTIVE

The aim of this study was to explore differences in functional connectivity and network organization between very preterm born adolescents and term born controls and to investigate if these differences might explain the relation between preterm birth and adverse long-term outcome.

METHODS

Forty-seven very preterm born adolescents (53% males) and 54 controls (54% males) with matching age, sex and parental educational levels underwent high-density electroencephalography (EEG) at 13 years of age. Long-term outcome was assessed by Intelligence Quotient (IQ), motor, attentional functioning and academic performance. Two minutes of EEG data were analysed within delta, theta, lower alpha, upper alpha and beta frequency bands. Within each frequency band, connectivity was assessed using the Phase Lag Index (PLI) and Amplitude Envelope Correlation, corrected for volume conduction (AEC-c). Brain networks were constructed using the minimum spanning tree method.

RESULTS

Very preterm born adolescents had stronger beta PLI connectivity and less differentiated network organization. Beta AEC-c and differentiation of AEC-c based networks were negatively associated with long-term outcomes. EEG measures did not mediate the relation between preterm birth and outcomes.

CONCLUSIONS

This study shows that very preterm born adolescents may have altered functional connectivity and brain network organization in the beta frequency band. Alterations in measures of functional connectivity and network topologies, especially its differentiating characteristics, were associated with neurodevelopmental functioning.

SIGNIFICANCE

The findings indicate that EEG connectivity and network analysis is a promising tool for investigating underlying mechanisms of impaired functioning.

The influence of nutrition on white matter development in preterm infants: a scoping review

White matter (WM) injury is the most common type of brain injury in preterm infants and is associated with impaired neurodevelopmental outcome (NDO). Currently, there are no treatments for WM injury, but optimal nutrition during early preterm life may support WM development. The main aim of this scoping review was to assess the influence of early postnatal nutrition on WM development in preterm infants. Searches were performed in PubMed, EMBASE, and COCHRANE on September 2022. Inclusion criteria were assessment of preterm infants, nutritional intake before 1 month corrected age, and WM outcome. Methods were congruent with the PRISMA-ScR checklist. Thirty-two articles were included. Negative associations were found between longer parenteral feeding duration and WM development, although likely confounded by illness. Positive associations between macronutrient, energy, and human milk intake and WM development were common, especially when fed enterally. Results on fatty acid and glutamine supplementation remained inconclusive. Significant associations were most often detected at the microstructural level using diffusion magnetic resonance imaging. Optimizing postnatal nutrition can positively influence WM development and subsequent NDO in preterm infants, but more controlled intervention studies using quantitative neuroimaging are needed. IMPACT: White matter brain injury is common in preterm infants and associated with impaired neurodevelopmental outcome. Optimizing postnatal nutrition can positively influence white matter development and subsequent neurodevelopmental outcome in preterm infants. More studies are needed, using quantitative neuroimaging techniques and interventional designs controlling for confounders, to define optimal nutritional intakes in preterm infants.

Early Nutritional Interventions for Brain and Cognitive Development in Preterm Infants: A Review of the Literature

Adequate nutrition is important for neurodevelopmental outcomes in preterm-born infants. In this review, we aim to summarize the current knowledge on nutritional interventions initiated during the hospital stay targeting brain and cognitive development benefits in preterm human infants. Studies can broadly be split in general dietary intervention studies and studies investigating specific nutrients or nutritional supplements. In general, mother's breast milk was reported to be better for preterm infants' neurodevelopment compared to infant formula. The differences in methodologies make it difficult to conclude any effects of interventions with individual nutrients. Only protein and iron level studies showed some consistent findings regarding optimal doses; however, confirmatory studies are needed. This review does not support some widely accepted associations, such as that between long-chain polyunsaturated fatty acid supplementation and visual development. Clear nutritional recommendations cannot be made based on this review. However, the type of infant nutrition (i.e., breast milk versus formula or donor milk), the timing of the nutritional intervention, and the dose of the nutrient/supplement have been found to be relevant factors in determining the success of nutritional intervention studies in preterm infants.

Glutamine supplementation to prevent morbidity and mortality in preterm infants

BACKGROUND

Glutamine is a conditionally essential amino acid. Endogenous biosynthesis may be insufficient for tissue needs in states of metabolic stress. Evidence exists that glutamine supplementation improves clinical outcomes in critically ill adults. It has been suggested that glutamine supplementation may also benefit preterm infants.

OBJECTIVES

To determine the effects of glutamine supplementation on mortality and morbidity in preterm infants.

SEARCH METHODS

We used the standard search strategy of the Cochrane Neonatal Review Group. This included searches of the Cochrane Central Register of Controlled Trials (CENTRAL, 2015, Issue 12), MEDLINE, EMBASE and Maternity and Infant Care (to December 2015), conference proceedings and previous reviews.

SELECTION CRITERIA

Randomised or quasi-randomised controlled trials that compared glutamine supplementation versus no glutamine supplementation in preterm infants at any time from birth to discharge from hospital.

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. We synthesised data using a fixed-effect model and reported typical relative risk, typical risk difference and weighted mean difference.

MAIN RESULTS

We identified 12 randomised controlled trials in which a total of 2877 preterm infants participated. Six trials assessed enteral glutamine supplementation and six trials assessed parenteral glutamine supplementation. The trials were generally of good methodological quality. Meta-analysis did not find an effect of glutamine supplementation on mortality (typical relative risk 0.97, 95% confidence interval 0.80 to 1.17; risk difference 0.00, 95% confidence interval -0.03 to 0.02) or major neonatal morbidities including the incidence of invasive infection or necrotising enterocolitis. Three trials that assessed neurodevelopmental outcomes in children aged 18 to 24 months and beyond did not find any effects.

AUTHORS' CONCLUSIONS

The available trial data do not provide evidence that glutamine supplementation confers important benefits for preterm infants.

Glutamine supplementation to prevent morbidity and mortality in preterm infants

BACKGROUND

Glutamine is a conditionally essential amino acid. Endogenous biosynthesis may be insufficient for tissue needs in states of metabolic stress. Evidence exists that glutamine supplementation improves clinical outcomes in critically ill adults. It has been suggested that glutamine supplementation may also benefit preterm infants.

OBJECTIVES

To determine the effects of glutamine supplementation on mortality and morbidity in preterm infants.

SEARCH METHODS

We used the standard search strategy of the Cochrane Neonatal Review Group. This included searches of the Cochrane Central Register of Controlled Trials (CENTRAL, 2015, Issue 12), MEDLINE, EMBASE and Maternity and Infant Care (to December 2015), conference proceedings and previous reviews.

SELECTION CRITERIA

Randomised or quasi-randomised controlled trials that compared glutamine supplementation versus no glutamine supplementation in preterm infants at any time from birth to discharge from hospital.

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. We synthesised data using a fixed-effect model and reported typical relative risk, typical risk difference and weighted mean difference.

MAIN RESULTS

We identified 12 randomised controlled trials in which a total of 2877 preterm infants participated. Six trials assessed enteral glutamine supplementation and six trials assessed parenteral glutamine supplementation. The trials were generally of good methodological quality. Meta-analysis did not find an effect of glutamine supplementation on mortality (typical relative risk 0.97, 95% confidence interval 0.80 to 1.17; risk difference 0.00, 95% confidence interval -0.03 to 0.02) or major neonatal morbidities including the incidence of invasive infection or necrotising enterocolitis. Three trials that assessed neurodevelopmental outcomes in children aged 18 to 24 months and beyond did not find any effects.

AUTHORS' CONCLUSIONS

The available trial data do not provide evidence that glutamine supplementation confers important benefits for preterm infants.

Impact of nutrition on brain development and its neuroprotective implications following preterm birth

The impact of nutrition on brain development in preterm infants has been increasingly appreciated. Early postnatal growth and nutrient intake have been demonstrated to influence brain growth and maturation with subsequent effects on neurodevelopment that persist into childhood and adolescence. Nutrition could also potentially protect against injury. Inflammation and perinatal infection play a crucial role in the pathogenesis of white matter injury, the most common pattern of brain injury in preterm infants. Therefore, nutritional components with immunomodulatory and/or anti-inflammatory effects may serve as neuroprotective agents. Moreover, growing evidence supports the existence of a microbiome-gut-brain axis. The microbiome is thought to interact with the brain through immunological, endocrine, and neural pathways. Consequently, nutritional components that may influence gut microbiota may also exert beneficial effects on the developing brain. Based on these properties, probiotics, prebiotic oligosaccharides, and certain amino acids are potential candidates for neuroprotection. In addition, the amino acid glutamine has been associated with a decrease in infectious morbidity in preterm infants. In conclusion, early postnatal nutrition is of major importance for brain growth and maturation. Additionally, certain nutritional components might play a neuroprotective role against white matter injury, through modulation of inflammation and infection, and may influence the microbiome-gut-brain axis.

Prebiotics in infants for prevention of allergy

BACKGROUND

Prebiotics (commonly oligosaccharides) added to infant feeds have the potential to prevent sensitisation of infants to dietary allergens.

OBJECTIVES

To determine the effect of prebiotic given to infants for the prevention of allergy.

SEARCH METHODS

We performed an updated search in August 2012 of the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2012, Issue 8), MEDLINE, EMBASE, conference proceedings, citations, expert informants and clinical trials registries.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials that compared the use of a prebiotic to no prebiotic, or a specific prebiotic compared to a different prebiotic in infants for prevention of allergy.

DATA COLLECTION AND ANALYSIS

Assessment of trial quality, data extraction and synthesis of data were performed using the standard methods of The Cochrane Collaboration.

MAIN RESULTS

The 2012 update identified 13 studies classified as ongoing or awaiting classification (yet to report allergy outcomes). Forty-three studies were excluded, primarily as no allergy data were reported, although none of these enrolled infants were at high risk of allergy. Four studies enrolling 1428 infants were eligible for inclusion. All studies were at high risk of attrition bias. Allergy outcomes were reported from four months to two years of age.Meta-analysis of two studies (226 infants) found no significant difference in infant asthma although significant heterogeneity was found between studies. Meta-analysis of four studies found a significant reduction in eczema (1218 infants, typical risk ratio 0.68, 95% CI 0.48 to 0.97; typical risk difference -0.04, 95% CI -0.07 to -0.00; number needed to treat to benefit (NNTB) 25, 95% CI 14 to > 100; P = 0.03). No statistically significant heterogeneity was found between studies. One study reported no significant difference in urticaria.No statistically significant subgroup differences were found according to infant risk of allergy or type of infant feed. However, individual studies reported a significant reduction in asthma and eczema from supplementation with a mixture of galacto- and fructo-oligosaccharide (GOS/FOS 9:1 ratio) (8 g/L) in infants at high risk of allergy; and in eczema from supplementation with GOS/FOS (9:1) (6.8 g/L) and acidic oligosacccharide (1.2 g/L) in infants not selected for allergy risk.

AUTHORS' CONCLUSIONS

Further research is needed before routine use of prebiotics can be recommended for prevention of allergy in formula fed infants. There is some evidence that a prebiotic supplement added to infant feeds may prevent eczema. It is unclear whether the use of prebiotic should be restricted to infants at high risk of allergy or may have an effect in low risk populations; or whether it may have an effect on other allergic diseases including asthma.

Glutamine randomized studies in early life: the unsolved riddle of experimental and clinical studies

Glutamine may have benefits during immaturity or critical illness in early life but its effects on outcome end hardpoints are controversial. Our aim was to review randomized studies on glutamine supplementation in pups, infants, and children examining whether glutamine affects outcome. Experimental work has proposed various mechanisms of glutamine action but none of the randomized studies in early life showed any effect on mortality and only a few showed some effect on inflammatory response, organ function, and a trend for infection control. Although apparently safe in animal models (pups), premature infants, and critically ill children, glutamine supplementation does not reduce mortality or late onset sepsis, and its routine use cannot be recommended in these sensitive populations. Large prospectively stratified trials are needed to better define the crucial interrelations of “glutamine-heat shock proteins-stress response” in critical illness and to identify the specific subgroups of premature neonates and critically ill infants or children who may have a greater need for glutamine and who may eventually benefit from its supplementation. The methodological problems noted in the reviewed randomized experimental and clinical trials should be seriously considered in any future well-designed large blinded randomized controlled trial involving glutamine supplementation in critical illness.

Placental pathology and long-term neurodevelopment of very preterm infants

OBJECTIVE

The objective of the study was to compare neonatal morbidity and long-term neurodevelopmental outcome between very preterm infants with placental underperfusion and very preterm infants with histological chorioamnionitis.

STUDY DESIGN

We measured the mental and motor development at age 2 and 7 years in 51 very preterm infants with placental underperfusion and 21 very preterm infants with histological chorioamnionitis.

RESULTS

At 2 years, very preterm infants with placental underperfusion had poorer mental development than very preterm infants with histological chorioamnionitis (mean [SD] 90.8 [18.3] vs 104.1 [17.2], adjusted d = 1.12, P = .001). Motor development was not different between both groups (92.8 [17.2] vs 96.8 [8.7], adjusted d = 0.52, P = .12). At 7 years, large, although nonsignificant, effects were found for better mental and motor development and fewer behavioral problems in infants with histological chorioamnionitis.

CONCLUSION

Placental pathology contributes to variance in mental development at 2 years and should be taken into account when evaluating neurodevelopmental outcome of very preterm infants.

Glutamine supplementation to prevent morbidity and mortality in preterm infants

BACKGROUND

Glutamine is a conditionally essential amino acid. Endogenous biosynthesis may be insufficient for tissue needs in states of metabolic stress. Evidence exists that glutamine supplementation improves clinical outcomes in critically ill adults. It has been suggested that glutamine supplementation may also benefit preterm infants.

OBJECTIVES

To determine the effects of glutamine supplementation on mortality and morbidity in preterm infants.

SEARCH METHODS

We used the standard search strategy of the Cochrane Neonatal Review Group. This included searches of the Cochrane Central Register of Controlled Trials (The Cochrane Library, 2011, Issue 4), MEDLINE, EMBASE and CINAHL (to November 2011), conference proceedings and previous reviews.

SELECTION CRITERIA

Randomised or quasi-randomised controlled trials that compared glutamine supplementation versus no glutamine supplementation in preterm infants at any time from birth to discharge from hospital.

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. We synthesised data using a fixed-effect model and reported typical relative risk, typical risk difference and weighted mean difference.

MAIN RESULTS

We identified 11 randomised controlled trials in which a total of 2771 preterm infants participated. Five trials assessed enteral glutamine supplementation and six trials assessed parenteral glutamine supplementation. The trials were generally of good methodological quality. Meta-analysis did not detect a statistically significant effect of glutamine supplementation on mortality [typical relative risk 0.98 (95% confidence interval 0.80 to 1.18); risk difference 0.00 (95% confidence interval -0.03 to 0.02)] or major neonatal morbidities including the incidence of invasive infection or necrotising enterocolitis. Two trials that assessed neurodevelopmental outcomes at 18 to 24 months did not find any statistically significant differences in various assessments.

AUTHORS' CONCLUSIONS

The available trial data do not provide evidence that glutamine supplementation confers important benefits for preterm infants.

Stability of cognitive outcome from 2 to 5 years of age in very low birth weight children

OBJECTIVES

This study assessed the stability of cognitive outcomes of premature, very low birth weight (VLBW; ≤1500 g) children.

METHODS

A regional cohort of 120 VLBW children born between 2001 and 2004 was followed up by using the Bayley Scales of Infant Development, Second Edition, at 2 years of corrected age and the Wechsler Preschool and Primary Scale of Intelligence-Revised at the age of 5 years. The Mental Development Index (MDI) and the full-scale IQ (FSIQ) were measured, respectively. A total of 168 randomly selected healthy term control children born in the same hospital were assessed for MDI and FSIQ.

RESULTS

In the VLBW group, mean ± SD MDI was 101.2 ± 16.3 (range: 50-128), mean FSIQ was 99.3 ± 17.7 (range: 39-132), and the correlation between MDI and FSIQ was 0.563 (P < .0001). In the term group, mean MDI was 109.8 ± 11.7 (range: 54-128), mean FSIQ was 111.7 ± 14.5 (range: 73-150), and the correlation between MDI and FSIQ was 0.400 (P < .0001). Overall, 83% of those VLBW children who had significant delay (-2 SD or less) according to MDI had it also in FSIQ. Similarly, 87% of those children who were in the average range in MDI were within the average range in FSIQ as well.

CONCLUSIONS

Good stability of cognitive development over time was found in VLBW children and in term children between the ages of 2 and 5 years. This conclusion stresses the value and clinical significance of early assessment at 2 years of corrected age. However, we also emphasize the importance of a long-term follow-up covering a detailed neuropsychological profile of these at-risk children.

Effects of neonatal enteral glutamine supplementation on cognitive, motor and behavioural outcomes in very preterm and/or very low birth weight children at school age

In very preterm ( < 32 weeks of gestation) and/or very low birth weight (VLBW, < 1500 g birth weight) children, serious neonatal infections are among the main causes of poor developmental outcomes later in childhood. The amino acid glutamine has been shown to reduce the incidence of serious neonatal infections in very preterm and/or VLBW children, while developmental effects beyond 24 months are unknown. We determined the cognitive, motor and behavioural outcomes at school age of a cohort of sixty-four very preterm and/or VLBW children (aged 7·5 (sd 0·4) years) who participated in a randomised placebo-controlled trial using enteral glutamine between day 3 and day 30 of life. Cognitive and motor outcomes were studied using the Wechsler Intelligence Scale for Children-III, the Movement Assessment Battery for Children (MABC), the Attention Network Test and a visual working memory task. Behavioural outcomes were evaluated using parent- and teacher-rated questionnaires. Intelligence quotient, processing speed, attentional functioning, working memory and parent- and teacher-rated behavioural outcomes were not different between children treated with glutamine or placebo; only visuomotor abilities as measured by the Ball Skills scale of the MABC (P = 0·002; d = 0·67) were poorer in the glutamine group. This effect persisted after taking into account the beneficial effects of lower serious neonatal infections rates in children treated with glutamine (P = 0·005). In conclusion, glutamine supplementation between day 3 and day 30 of life had neither beneficial nor detrimental effects on long-term cognitive, motor and behavioural outcomes of very preterm and/or VLBW children at school age, although visuomotor abilities were poorer in children that received glutamine.

Glutamine supplementation in sick children: is it beneficial?

The purpose of this review is to provide a critical appraisal of the literature on Glutamine (Gln) supplementation in various conditions or illnesses that affect children, from neonates to adolescents. First, a general overview of the proposed mechanisms for the beneficial effects of Gln is provided, and subsequently clinical studies are discussed. Despite safety, studies are conflicting, partly due to different effects of enteral and parenteral Gln supplementation. Further insufficient evidence is available on the benefits of Gln supplementation in pediatric patients. This includes premature infants, infants with gastrointestinal disease, children with Crohn's disease, short bowel syndrome, malnutrition/diarrhea, cancer, severe burns/trauma, Duchenne muscular dystrophy, sickle cell anemia, cystic fibrosis, and type 1 diabetes. Moreover, methodological issues have been noted in some studies. Further mechanistic data is needed along with large randomized controlled trials in select populations of sick children, who may eventually benefit from supplemental Gln.

Neutral and acidic oligosaccharides in preterm infants: a randomized, double-blind, placebo-controlled trial

BACKGROUND

Serious infectious morbidity is high in preterm infants. Enteral supplementation of prebiotics may reduce the incidence of serious infections, especially infections related to the gastrointestinal tract.

OBJECTIVE

The objective was to determine the effect of enteral supplementation of a prebiotic mixture consisting of neutral oligosaccharides ((SC)GOS/(LC)FOS) and acidic oligosaccharides (AOS) on serious infectious morbidity in preterm infants.

DESIGN

In a randomized controlled trial, preterm infants (gestational age <32 wk and/or birth weight <1500 g) received enteral supplementation of 80% (SC)GOS/(LC)FOS and 20% AOS (1.5 g . kg(-1) . d(-1)) or placebo (maltodextrin) between days 3 and 30 of life. Serious infectious morbidity was defined as a culture positive for sepsis, meningitis, pyelonephritis, or pneumonia. The analysis was performed by intention-to-treat and per-protocol, defined as > or =50% supplementation dose during the study period.

RESULTS

In total, 113 preterm infants were included. Baseline and nutritional characteristics were not different between groups. In the intention-to-treat analysis, the incidence of > or =1 serious infection, > or =1 serious endogenous infection, or > or =2 serious infectious episodes was not significantly different in the (SC)GOS/(LC)FOS/AOS-supplemented and placebo groups. In the per-protocol analysis, there was a trend toward a lower incidence of > or =1 serious endogenous infection and > or =2 serious infectious episodes in the (SC)GOS/(LC)FOS/AOS-supplemented group than in the placebo group (P = 0.09 and P = 0.07, respectively).

CONCLUSIONS

Enteral supplementation of (SC)GOS/(LC)FOS/AOS does not significantly reduce the risk of serious infectious morbidity in preterm infants. However, there was a trend toward a lower incidence of serious infectious morbidity, especially for infections with endogenous bacteria. This finding suggests a possible beneficial effect that should be evaluated in a larger study. This trial was registered at isrctn.org as ISRCTN16211826.

Cognitive outcome at 2 years of age in Finnish infants with very low birth weight born between 2001 and 2006

AIM

To study cognitive outcome of premature, very low birth weight (VLBW) infants in relation to parental education and neonatal data.

METHODS

A regional cohort of 182 VLBW infants born between 2001 and 2006 was followed up. Brain ultrasounds (US) were examined serially until term age and brain magnetic resonance imaging at term age. Neurological status was examined systematically. Cognitive development was assessed using the Mental Developmental Index (MDI) of Bayley Scales at 2 years of corrected age. A total of 192 healthy full-term (FT) controls were assessed with the MDI at 2 years of age.

RESULTS

The mean MDI in VLBW infants was 101.7 (SD 15.4), which was lower compared with FT controls (109.8, SD 11.7, p < 0.001). In regression analysis of the demographic and medical data of VLBW infants, postnatal corticosteroids (p = 0.04), intestinal perforation (p = 0.03) and major brain pathology (p = 0.02) were negatively associated with the MDI. In VLBW infants, the prevalence of neurodevelopmental impairment was 9.9% (3.3% MDI below 70, 7.1% cerebral palsy, 2.2% hearing aid, no blind infants).

CONCLUSION

Cognitive development of VLBW infants seemed to have improved in comparison with earlier publications, but it differed from the FT controls. Neonatal factors affected cognitive development. Therefore, updated regional follow-up data are important for clinicians.