Epidemiology of Necrotizing Enterocolitis: New Considerations Regarding the Influence of Red Blood Cell Transfusions and Anemia

A Detailed Protocol for the Induction of Anemia and RBC Transfusion-associated Necrotizing Enterocolitis in Neonatal Mice

Anemia is a common and serious health problem, nearly universally diagnosed in preterm infants, and is associated with increased morbidity and mortality worldwide. Red blood cell (RBC) transfusion is a lifesaving and mainstay therapy; however, it has critical adverse effects. One consequence is necrotizing enterocolitis (NEC), an inflammatory bowel necrosis disease in preterm infants. The murine model of phlebotomy-induced anemia and RBC transfusion-associated NEC enables a detailed study of the molecular mechanisms underlying these morbidities and the evaluation of potential new therapeutic strategies. This protocol describes a detailed procedure for obtaining murine pups with phlebotomy-induced anemia and delivering an RBC transfusion that develops NEC.

Timing of Red Blood Cell Transfusions and Occurrence of Necrotizing Enterocolitis: A Secondary Analysis of a Randomized Clinical Trial

Importance

Observational studies often report that anemia and red blood cell (RBC) transfusions are associated with a higher risk of necrotizing enterocolitis (NEC) among extremely low-birthweight (ELBW) infants.

Objective

To evaluate whether there is a temporal association between 72-hour hazard periods of exposure to RBC transfusions and NEC among ELBW infants randomized to either higher or lower hemoglobin transfusion thresholds.

Design, Setting, and Participants

This post hoc secondary analysis of 1690 ELBW infants who survived to postnatal day 10 enrolled in the Transfusion of Prematures (TOP) randomized multicenter trial between December 1, 2012, and April 12, 2017, was performed between June 2021 and July 2023.

Exposures

First, the distribution of RBC transfusions and the occurrence of NEC up to postnatal day 60 were examined. Second, 72-hour posttransfusion periods were categorized as hazard periods and the pretransfusion periods of variable duration as control periods. Then, the risk of NEC in posttransfusion hazard periods was compared with that in pretransfusion control periods, stratifying the risk based on randomization group (higher or lower hemoglobin transfusion threshold group).

Main Outcomes and Measures

The primary outcome was incidence of NEC stage 2 or 3. Secondary outcomes included the incidence rates of NEC within five 10-day intervals, taking into account the number of days at risk.

Results

Of 1824 ELBW infants randomized during the TOP trial, 1690 were included in the present analysis (mean [SD] gestational age, 26.0 [1.5] weeks; 899 infants [53.2%] were female). After categorizing 4947 hazard periods and 5813 control periods, we identified 133 NEC cases. Fifty-nine of these cases (44.4%) occurred during hazard periods. Baseline and clinical characteristics of infants with NEC during hazard periods did not differ from those of infants with NEC during control periods. The risk of NEC was 11.9 per 1000 posttransfusion hazard periods and 12.7 per 1000 control periods (adjusted risk ratio, 0.95; 95% CI, 0.68-1.32; P = .74). This risk did not differ significantly between randomization groups, but the incidence rate of NEC per 1000 days peaked between postnatal days 20 and 29 in the lower hemoglobin transfusion threshold group.

Conclusions and Relevance

The findings of this post hoc analysis suggest that, among ELBW infants with the hemoglobin ranges occurring in the TOP trial, exposure to RBC transfusions was not temporally associated with a higher risk of NEC during 72-hour posttransfusion hazard periods. Given that the incidence rate of NEC peaked between postnatal days 20 and 29 among infants with lower hemoglobin values, a more in-depth examination of this at-risk period using larger data sets is warranted.

Trial Registration

ClinicalTrials.gov Identifier: NCT01702805.

Near-Infrared Spectroscopy to Guide and Understand Effects of Red Blood Cell Transfusion

This review is a summary of available evidence regarding the use of near-infrared spectroscopy (NIRS) to help better guide and understand the effects of red blood cell (RBC) transfusion in neonatal patients. We review recent literature demonstrating the changes that take place in regional tissue oxygen saturation (rSO2) resulting from RBC transfusion. We also discuss in detail if any correlation exists between rSO2 and hemoglobin values in neonates. Finally, we review studies that have evaluated the use of NIRS as a transfusion guide during neonatal intensive care.

The Outcome of Blood Transfusions in Conservative and Surgical Necrotizing Enterocolitis and Spontaneous Intestinal Perforation

INTRODUCTION

 In necrotizing enterocolitis (NEC), blood transfusions (BTs) are a disputed factor concerning the etiology and the outcome. We assessed retrospectively the effects of preonset BT on the outcome of NEC and spontaneous intestinal perforation (SIP).

MATERIALS AND METHODS

 With ethical consent, we reviewed the hospital records of 113 neonates from 2002 to 2019 with surgical NEC (NECs) (n = 57), conservatively treated NEC (NECc) (n = 20), and SIP (n = 36). The onset was defined as the day of surgery (NECs and SIP) or diagnosis (NECc). The effects of preonset BT (total, beyond 48 hours, and within 48 hours) were compared with the effects of birth weight (BW), gestational age (GA), intracerebral hemorrhage, respiratory distress syndrome, septicemia, and patent ductus arteriosus. Main outcome measure was 2-week mortality, and secondary measures were small intestinal loss and days on parenteral nutrition (PN).

RESULTS

 Overall mortality (8.9%) was predicted independently by BT total and BT beyond 48 hours, risk ratio (RR) = 1.1 to 1.2 (95% confidence interval [CI] = 1.0-1.4), p = 0.01 to 0.02, and BW and GA, RR = 0.7 to 1.0 (95% CI = 0.5-1.0), p = 0.02 to 0.04. Mortality in NECs (12%) was predicted by BT total and BT beyond 48 hours only, RR = 1.1 to 1.2 (95% CI = 1.0-1.5), p = 0.03 to 0.04. BT within 48 hours of onset did not predict mortality. No factors were related with secondary outcome measures or with mortality in patients with SIP or NECc.

CONCLUSION

 In NECs, preoperative BT and BT given more than 48 hours before surgery were correlated with slightly increased 2-week mortality but not with small intestinal loss or duration of PN.

Enteral Iron Supplementation in Infants Born Extremely Preterm and its Positive Correlation with Neurodevelopment; Post Hoc Analysis of the Preterm Erythropoietin Neuroprotection Trial Randomized Controlled Trial

OBJECTIVES

To test whether an increased iron dose is associated with improved neurodevelopment as assessed by the Bayley Scales of Infant Development, third edition (BSID-III) among infants enrolled in the Preterm Erythropoietin (Epo) Neuroprotection Trial (PENUT).

STUDY DESIGN

This is a post hoc analysis of a randomized trial that enrolled infants born at 24-28 completed weeks of gestation. All infants in PENUT who were assessed with BSID-III at 2 years were included in this study. The associations between enteral iron dose at 60 and 90 days and BSID-III component scores were evaluated using generalized estimating equations models adjusted for potential confounders.

RESULTS

In total, 692 infants were analyzed (355 placebo, 337 Epo). Enteral iron supplementation ranged from 0 to 14.7 mg/kg/d (IQR 2.1-5.8 mg/kg/d) at day 60, with a mean of 3.6 mg/kg/d in infants treated with placebo and 4.8 mg/kg/d in infants treated with Epo. A significant positive association was seen between BSID-III cognitive scores and iron dose at 60 days, with an effect size of 0.77 BSID points per 50 mg/kg increase in cumulative iron dose (P = .03). Greater iron doses were associated with greater motor and language scores but did not reach statistical significance. Results at 90 days were not significant. The effect size in the infants treated with Epo compared with placebo was consistently greater.

CONCLUSIONS

A positive association was seen between iron dose at 60 days and cognitive outcomes. Our results suggest that increased iron supplementation in infants born preterm, at the doses administered in the PENUT Trial, may have positive neurodevelopmental effects, particularly in infants treated with Epo.

TRIAL REGISTRATION

Clinicaltrials.gov: NCT01378273.

Neonatal Transfusion Practice: Hemolysis Markers After In Vitro Infusion of Packed Red Blood Cells by the Gravitational Method or Syringe Pump in a Peripheral Catheter

The objective of this study was to verify the influence of the gravitational infusion method or syringe infusion pump on changes in hemolysis markers of irradiated and nonirradiated packed red blood cells (PRBCs) in vitro administered in a neonate peripheral intravenous catheter. An experimental study was conducted in a laboratory under controlled environmental conditions. Irradiated and nonirradiated PRBCs were administered in triplicate by the gravitational method and 10-mL/hour syringe infusion pump, in peripheral intravenous catheter, Vialon, 24-G caliber. Aliquots were collected directly from the PRBC bag, after manual filling of the infusion system and after infusion by the catheters. The following hemolytic markers were analyzed: degree of hemolysis (%), hematocrit (Ht, %), free hemoglobin (fHb, g/dL), potassium (K, mmol/L), and lactate dehydrogenase (LDH, U/L). Mann-Whitney and Student's t tests were used, P ≤ .05. The gravitational method significantly influenced increasing fHb (P = .007), Ht (P = .002), K (P = .002), and LDH (P = .003) values after PRBC irradiated infusion. The infusion of irradiated and non-irradiated PRBCs interferes with changes in hemolytic markers with the gravitational method. Syringe infusion pump proved to be a beneficial and safe alternative to irradiated and nonirradiated PRBC transfusion in newborns.

Turkish Neonatal Society Necrotizing Enterocolitis Diagnosis, Treatment and Prevention Guidelines

Necrotizing enterocolitis (NEC) is one of the most common gastrointestinal emergencies in the newborn infant, and the incidence varies between 3% and 15% in neonatal intensive care units (NICU). It has a high risk of mortality and both short- and long-term morbidity which severely impacts the quality of life in the survivors. Lack of specific clinical and laboratory findings makes early diagnosis difficult for the clinician and sometimes results in overtreatment for feeding intolerance which is quite frequent in preterms and can easily be confused with NEC. The fact that there are many definitions and presentations of NEC even complicates the management. This review aims to summarize the guideline of the Turkish Neonatal Society for diagnosis, treatment, and prevention of NEC for the clinician taking care of preterms. Etiopathogenesis and various clinical pictures of NEC, as well as diagnostic methods, are defined. Treatment and prognosis are discussed in detail with reference to current literature and preventive strategies are summarized based on evidence. Finally, the approach to baby presenting with suspected NEC is summarized in an algorithm.

Transfusions and neurodevelopmental outcomes in extremely low gestation neonates enrolled in the PENUT Trial: a randomized clinical trial

BACKGROUND

Outcomes of extremely low gestational age neonates (ELGANs) may be adversely impacted by packed red blood cell (pRBC) transfusions. We investigated the impact of transfusions on neurodevelopmental outcome in the Preterm Erythropoietin (Epo) Neuroprotection (PENUT) Trial population.

METHODS

This is a post hoc analysis of 936 infants 24-0/6 to 27-6/7 weeks' gestation enrolled in the PENUT Trial. Epo 1000 U/kg or placebo was given every 48 h × 6 doses, followed by 400 U/kg or sham injections 3 times a week through 32 weeks postmenstrual age. Six hundred and twenty-eight (315 placebo, 313 Epo) survived and were assessed at 2 years of age. We evaluated associations between BSID-III scores and the number and volume of pRBC transfusions.

RESULTS

Each transfusion was associated with a decrease in mean cognitive score of 0.96 (95% CI of [-1.34, -0.57]), a decrease in mean motor score of 1.51 (-1.91, -1.12), and a decrease in mean language score of 1.10 (-1.54, -0.66). Significant negative associations between BSID-III score and transfusion volume and donor exposure were observed in the placebo group but not in the Epo group.

CONCLUSIONS

Transfusions in ELGANs were associated with worse outcomes. We speculate that strategies to minimize the need for transfusions may improve outcomes.

IMPACT

Transfusion number, volume, and donor exposure in the neonatal period are associated with worse neurodevelopmental (ND) outcome at 2 years of age, as assessed by the Bayley Infant Scales of Development, Third Edition (BSID-III). The impact of neonatal packed red blood cell transfusions on the neurodevelopmental outcome of preterm infants is unknown. We speculate that strategies to minimize the need for transfusions may improve neurodevelopmental outcomes.

Pediatric Hemovigilance and Adverse Transfusion Reactions

Some types of transfusion reactions occur more frequently in the pediatric than the adult population. Allergic reactions are the most common, followed by nonhemolytic transfusion reactions; male children seem most susceptible to such reactions. Platelets are often implicated and pulmonary reactions are understudied in children. Clinical sequelae in neonates, such as bronchopulmonary dysplasia/chronic lung disease and intraventricular hemorrhage, have received increasing attention in relation to transfusion. There is a need to better understand the pathophysiology of transfusion reactions in neonatal and pediatric populations so preventive strategies can be undertaken. There is also a need for robust hemovigilance systems.

Red blood cell transfusions and potentially related morbidities in neonates under 32 weeks' gestation

BACKGROUND

Preterm neonates are likely to require red blood cell (RBC) transfusion, and extremely low birth weight infants almost invariably receive multiple transfusions. Transfusion-reduction strategies can reduce transfusion rates, and might diminish certain adverse outcomes associated with transfusions.

MATERIALS AND METHODS

In a single centre, we retrospectively evaluated RBC transfusion rates among preterm infants ≤32 weeks' gestational age (GA), over a 6-year period before and after adopting national transfusion-reduction strategies. We compared demographic data, adverse events, and outcomes between transfused vs not-transfused neonates. Univariate logistic regression was used to evaluate associations between dichotomous outcomes and number of transfusions, and day of first transfusion. Multivariate logistic regression evaluated the correlation between dichotomous outcomes and transfusion as an independent risk factor.

RESULTS

During the 6 years studied, 181 infants born at ≤32 weeks' GA were admitted to our Neonatal Intensive Care Unit of whom 80 (44%) received at least one RBC transfusion. The transfusion rate tended downwards after adopting transfusion-reduction strategies, reaching 31% in 2018. The reduction was largely due to a marked fall in transfusions of neonates born at 29-32 weeks' GA (p<0.001). The number of transfusions received correlated with odds of having intraventricular haemorrhage (IVH) (OR=1.9; 95% CI: 1.3-2.7; p=0.0001) and the duration of oxygen supplementation (rho=0.51; 95% CI: 0.33-0.66; p≤0.0001). In multivariate logistic regression analysis, transfusion was an independent risk factor for IVH (adjusted OR=7.38; 95% CI: 2.24-24.30; p=0.0001).

DISCUSSION

The application of national, standardised transfusion-reduction strategies was associated with a lower transfusion rate in neonates born at 29-32 weeks' GA, but was less effective among neonates ≤28 weeks, in whom transfusions appeared to be an independent risk factor for severe IVH.

New directions in necrotizing enterocolitis with early-stage investigators

The 2019 Necrotizing Enterocolitis (NEC) Symposium expanded upon the NEC Society's goals of bringing stakeholders together to discuss cutting-edge science, potential therapeutics and preventative measures, as well as the patient-family perspectives of NEC. The Symposium facilitated discussions and shared knowledge with the overarching goal of creating "A World Without NEC." To accomplish this goal, new research to advance the state of the science is necessary. Over the last decade, several established investigators have significantly improved our understanding of the pathophysiology of NEC and they have paved the way for the next generation of clinician-scientists funded to perform NEC research. This article will serve to highlight the contributions of these young clinician-scientists that seek to elucidate how immune, microbial and nervous system dysregulation contributes to the pathophysiology of NEC.

Transfusion-related Gut Injury and Necrotizing Enterocolitis

Necrotizing enterocolitis (NEC) accounts for 10% of deaths in neonatal intensive care units. Several causal mechanisms are likely to lead to a final common disease phenotype. This article summarizes recent data on NEC following red blood cell (RBC) transfusion, with a focus on the most recent literature and ongoing trials. It highlights potential mechanisms from preclinical and human physiologic studies. It also discusses the role of feeding during RBC transfusion and the risk of NEC. Ongoing randomized trials will provide important data on how liberal or conservative approaches to RBC transfusion influence the risk of NEC.

To start or not: Factors to consider when implementing routine probiotic use in the NICU

Supplementation of probiotics to very low birth weight (VLBW) infants has been extensively studied, with multiple meta-analyses reporting probiotics decrease the risk of necrotizing enterocolitis (NEC) and death. Despite availability of this evidence, the decision to initiate routine probiotic supplementation to preterm infants continues to be a complex one. There are uncertainties regarding the use of probiotics, including selecting the appropriate product, dose and target population. Additionally, availability of specific probiotic products and regulatory oversight varies by country, raising concerns regarding the safety and efficacy of specific probiotic products. In this review, we summarize the latest evidence on probiotic use in preterm infants and discuss considerations that may help guide clinicians who are considering routine probiotic supplementation.