Do red cell transfusions increase the risk of necrotizing enterocolitis in premature infants?

Severe anemia predisposes very premature infants to transfusion-associated necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a catastrophic inflammatory bowel necrosis of premature infants. The etiology is unknown, but 25-40 % of cases have a history of red blood cell (RBC) transfusions in the preceding 48 h. This association has been noted in retrospective case/case-control studies, and many meta-analyses, and in a murine model. However, we still need human studies with larger, adequately powered cohorts to confirm this association and determine the operant mechanisms. The murine model shows that severe anemia leads to macrophage infiltration in the gut mucosa. Subsequent RBC transfusions containing free hemoglobin, activate nuclear factor-kappa B-mediated inflammatory changes and cause NEC-like mucosal injury. This review summarizes current human and experimental data to evaluate ta-NEC and hitherto unanswered mechanistic questions. If a causal relationship between transfusions and NEC is proven, these data could help develop effective therapeutic strategies.

The effect of haemoglobin and blood transfusion on preterm infant gut perfusion and injury

Introduction

There is significant uncertainty regarding the role that anaemia or red blood cell transfusion (RBCT) plays in the development of gut injury in preterm infants. This study evaluated Near Infrared Spectroscopy (NIRS) together with a range of known biomarkers of gut inflammation to identify their relationship with anaemia and RBCT.

Method

A prospective observational study of preterm infants born at <30 weeks gestation was conducted from birth until either 36 weeks post conceptional age or discharge home. Gut perfusion and biomarkers of gut injury were assessed weekly by: 60 min NIRS measurements (splanchnic tissue oxygenation index [sTOI] and fractional tissue oxygenation extraction [sFTOE]); stool calprotectin; urine intestinal and liver fatty acid binding proteins (I-FABPs and L-FABPs); and trefoil factor 3 (TFF-3). Exclusion criteria included Fetal Growth Restriction (FGR), and abnormal antenatal Dopplers. Haemoglobin (Hb) levels were measured in parallel with NIRS measurements. NIRS, together with urine and stool biomarkers of gut injury, were evaluated up to 72 h pre/post RBCT and pre/post measurements compared.

Results

Forty-eight infants were studied. Median (range) gestational age was 26 + 3 (23 + 0 to 29 + 6) weeks and birthweight 883.5 g (460-1,600). Seven (14.6%) infants developed ≥ Bells stage 2 NEC. 28 (58.3%), 5 (10.4%) and 24 (50%) infants had ECHO confirmed PDA, haemorrhagic parenchymal infarct (HPI) and IVH respectively. There were 22 episodes of sepsis. Infants were in the study for a median of 7.3 (1-13) weeks. There was no significant association between Hb divided into three categories (<80 g/L, 80-111.9 g/L and ≥120 g/L) or continuous values and sTOI, sFTOE or any of the gut injury biomarkers measured (p > 0.05). 283 RBCTs were administered; 117 (41.3%) within the first two weeks of life. Pre and post blood transfusion changes in splanchnic NIRS oxygenation, urine and stool gut injury biomarkers were measured in 165, 195 and 175 episodes of RBCT respectively. There was no significant post RBCT changes in splanchnic NIRS or gut injury biomarker levels (p > 0.05). However, post RBCT calprotectin was significantly reduced during the first 14 days of life (mean difference -114%, CI -185 to -42 & p 0.002).

Conclusion

There was no association between anaemia or RBCT with NIRS measurements of tissue oxygen saturation and biomarkers of intestinal inflammation or gut injury in preterm infants enrolled in this study. Further studies with standardised methods of examining the relationship between anaemia, RBCT and gut injury are needed.

Stored RBC transfusions leads to the systemic inflammatory response syndrome in anemic murine neonates

OBJECTIVE

RBC transfusions (RBCT) are life-saving treatment for premature and critically ill infants. However, the procedure has been associated with the development of systemic inflammatory response syndrome (SIRS) and potentially multiple organ dysfunction syndrome (MODS) in neonates. The present study aimed to investigate the mechanisms of RBCT-related SIRS in severely anemic murine neonates.

METHODS

C57BL/6 (WT), TLR4-/- and myeloid-specific triggered myeloid receptor-1 (trem1)-/- mouse pups were studied in 4 groups (n = 6 each): (1) naïve controls, (2) transfused control, (3) anemic (hematocrit 20-24%) and (4) anemic with RBC transfused using our established murine model of phlebotomy-induced anemia (PIA) and RBC transfusion. Plasma was measured for quantifying inflammatory cytokines (IFN-γ, IL-1β, TNF-α, IL-6, MIP-1α, MIP-1β, MIP2 and LIX) using a Luminex assay. In vitro studies included (i) sensitization by exposing the cells to a low level of lipopolysaccharide (LPS; 500 ng/ml) and (ii) trem1-siRNA transfection with/without plasma supernatant from stored RBC to assess the acute inflammatory response through trem1 by qRT-PCR and immunoblotting.

RESULTS

Anemic murine pups developed cytokine storm within 2 h of receiving stored RBCs, which increased until 6 h post-transfusion, as compared to non-anemic mice receiving stored RBCTs ("transfusion controls"), in a TLR4-independent fashion. Nonetheless, severely anemic pups had elevated circulating endotoxin levels, thereby sensitizing circulating monocytes to presynthesize proinflammatory cytokines (IFN-γ, IL-1β, TNF-α, IL-6, MIP-1α, MIP-1β, MIP2, LIX) and express trem1. Silencing trem1 expression in Raw264.7 cells mitigated both endotoxin-associated presynthesis of proinflammatory cytokines and the RBCT-induced release of inflammatory cytokines. Indeed, myeloid-specific trem1-/- murine pups had significantly reduced evidence of SIRS following RBCTs.

CONCLUSION

Severe anemia-associated low-grade inflammation sensitizes monocytes to enhance the synthesis of proinflammatory cytokines and trem1. In this setting, RBCTs further activate these monocytes, thereby inducing SIRS. Inhibiting trem1 in myeloid cells, including monocytes, alleviates the inflammatory response associated with the combined effects of anemia and RBCTs in murine neonates.

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.

Evaluation of the impact of diagnostic blood loss and red blood cell transfusion in very-low-birth-weight anaemic neonates during hospitalization: A multi-centre retrospective clinical study

BACKGROUND AND OBJECTIVES

Diagnostic blood loss is a significant factor in the development of anaemia in neonates with very low birth weight. This study aimed to assess the clinical efficacy of intervention approaches involving varying diagnostic blood loss and red blood cell transfusion volumes in neonates with very low birth weights experiencing anaemia during hospitalization.

MATERIALS AND METHODS

A total of 785 newborns with anaemia weighing less than 1500 g were enrolled from 32 hospitals in China. The study involved monitoring diagnostic blood loss and red blood cell transfusion and evaluating relevant interventions such as red blood cell transfusion and clinical outcomes. Three intervention approaches were established based on the difference between blood loss and transfusion (Intervention Approaches 0, 1 and 2). The primary outcomes measured were unsatisfactory weight gain during hospitalization and neonatal mortality. The secondary outcomes included related complications.

RESULTS

In the non-hospital-acquired anaemia group, Intervention Approach 2 had the highest incidence of below-normal weight gain (odds ratio [OR]: 3.019, 95% confidence interval [CI]: 1.081-8.431, p = 0.035). Multivariate analysis revealed that Intervention Approach 1 had a protective effect on weight gain. In the hospital-acquired anaemia group, Intervention Approach 2 had the highest incidence of below-normal weight gain (OR: 3.335, 95% CI: 1.785-6.234, p = 0.000) and mortality (OR: 5.341, 95% CI: 2.449-11.645, p = 0.000), while Intervention Approach 1 had the lowest incidence of intraventricular haemorrhage. Intervention Approach 1 demonstrated favourable outcomes in both anaemia groups.

CONCLUSION

Intervention Approach 1 improved weight gain and reduced mortality and complications in both the non-hospital-acquired and hospital-acquired anaemia groups.

Retrospective cohort study of neonatal blood transfusion in China

BACKGROUND

Blood transfusion therapy is extremely important for certain neonatal diseases, but the threshold for neonatal blood transfusion is not the same in different countries. Until now, clinical studies to determine the suitable threshold for newborns in China are lacking. Therefore, it is of high importance to establish a multi-center cohort study to explore appropriate transfusion thresholds for newborns in China.

METHODS

This retrospective cohort study investigated neonatal blood transfusion therapy administered from January 1, 2017 to June 30, 2018, with the aim of evaluating the effect of restricted and nonrestricted blood transfusion on neonatal health. The subjects were enrolled in 46 hospitals in China. A total of 5669 neonatal cases were included in the study. Clinical diagnosis and transfusion treatment of these neonates were collected and the data were retrospectively analyzed. The neonates were followed up 1 week and 1 month after leaving the hospital. The newborns' and their mothers' data were collected containing 280 variables in the database. The primary outcome of the study was mortality, and the secondary outcomes were complications, hospital stays, NICU hospital stays and hospital costs.

RESULTS

Results from the < 1500 g group showed that there was a higher mortality rate in the restricted transfusion group (11.41%) when compared with the non-restricted transfusion group (5.12%) (P = 0.000). Among the secondary outcomes, the restricted transfusion group had fewer costs. Results from the 1500-2500 g group showed that the mortality rates of the restricted and non-restricted transfusion groups were 3.53% and 4.71%, respectively, however there was no statistical significance between the two groups (P = 0.345). Among the secondary outcomes, the restricted transfusion group had fewer hospital stays, NICU hospital stays and hospital costs. The incidence of necrotizing enterocolitis was lower in the restricted transfusion group (OR, 2.626; 95% confidence interval [CI], 1.445 to 4.773; P = 0.003). The results from the ≥ 2500 g restricted transfusion group suggested that the mortality rate of (3.02%) was significantly lower than that of non-restricted transfusion group (9.55%) (P = 0.000). Among the secondary outcomes, the restricted transfusion group had fewer hospital stays and hospital costs. The incidence of retinopathy of prematurity was lower in the restricted transfusion group (OR, 4.624; 95% confidence interval [CI], 2.32 to 9.216; P = 0.000).

CONCLUSIONS

Current transfusion protocols for newborns weighing less than 1500 g may be inappropriate and lead to higher mortality. The current transfusion threshold performed better for the other two weight groups.

Development of necrotizing enterocolitis after blood transfusion in very premature neonates

BACKGROUND

Prior studies report conflicting evidence on the association between packed red blood cell (PRBC) transfusions and necrotizing enterocolitis (NEC), especially in early weeks of life where transfusions are frequent and spontaneous intestinal perforation can mimic NEC. The primary objective of this study was to evaluate the association between PRBC transfusions and NEC after day of life (DOL) 14 in very premature neonates.

METHODS

A retrospective cohort analysis of very premature neonates was conducted to investigate association between PRBC transfusions and NEC after DOL 14. Primary endpoints were PRBC transfusions after DOL 14 until the date of NEC diagnosis, discharge, or death. Wilcoxon ranked-sum and Fisher's exact tests, Cox proportional hazards regression, and Kaplan-Meier curves were used to analyze data.

RESULTS

Of 549 premature neonates, 186 (34%) received transfusions after DOL 14 and nine (2%) developed NEC (median DOL = 38; interquartile range = 32-46). Of the nine with NEC after DOL 14, all were previously transfused (P < 0.001); therefore, hazard of NEC could not be estimated. Post hoc analysis of patients from DOL 10 onward included five additional patients who developed NEC between DOL 10 and DOL 14, and the hazard of NEC increased by a factor of nearly six after PRBC transfusion (hazard ratio = 5.76, 95% confidence interval = 1.02-32.7; P = 0.048).

CONCLUSIONS

Transfusions were strongly associated with NEC after DOL 14. Prospective studies are needed to determine if restrictive transfusion practices can decrease incidence of NEC after DOL 14.

Transfusion reactions in neonates and pediatrics: How and why are they different?

Neonates and children are physically as well as physiologically different from adults. They are immunologically vulnerable, and the effects of transfusion can be longstanding, including with respect to their development. The transfusion reactions in children differ from those in adults in the type of reactions, incidence, and severity. The incidence is more than that in adults for the common type of reactions noted in children. Transfusion reactions are most commonly associated with platelets, followed by plasma and red blood cell transfusions in children. Febrile, allergic, and hypotensive reactions or volume overload are the common types in children. Standardizing pediatric adverse transfusion reaction definitions and criteria are necessary to improve studies and reports. Several modifications are needed to be adapted for transfusing blood products in neonates and children to evade the reactions as much as possible and make transfusion safer in this vulnerable population. This article provides a brief articulation of the transfusion reactions in neonatal and pediatric populations describing how they are different from adults.

Association between prognostic factors and the clinical deterioration of preterm neonates with necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is responsible for most morbidity and mortality in neonates. Early recognition of the clinical deterioration in newborns with NEC is essential to enhance the referral and management and potentially improve the outcomes. Here, we aimed to identify the prognostic factors and associate them with the clinical deterioration of preterm neonates with NEC. We analyzed the medical records of neonates with NEC admitted to our hospital from 2016 to 2021. We ascertained 214 neonates with NEC. The area under the receiver operating characteristic (ROC) curve and cut-off level of age at onset, C-reactive protein (CRP), leukocyte count, and platelet count for the clinical deterioration of preterm neonates with NEC was 0.644 and 10.5 days old, 0.694 and 4.5 mg/L, 0.513 and 12,200/mm³, and 0.418 and 79,500/mm³, respectively. Late-onset, history of blood transfusion, thrombocytopenia, and elevated CRP were significantly associated with the clinical deterioration of neonates with NEC (p =  < 0.001, 0.017, 0.001, and < 0.001, respectively), while leukocytosis, gestational age, and birth weight were not (p = 0.073, 0.274, and 0.637, respectively). Multivariate analysis revealed that late-onset and elevated CRP were strongly associated with the clinical deterioration of neonates with NEC, with an odds ratio of 3.25 (95% CI = 1.49-7.09; p = 0.003) and 3.53 (95% CI = 1.57-7.95; p = 0.002), respectively. We reveal that late-onset and elevated CRP are the independent prognostic factor for the clinical deterioration of preterm neonates with NEC. Our findings suggest that we should closely monitor preterm neonates with NEC, particularly those with late-onset of the disease and those with an elevated CRP, to prevent further clinical deterioration and intervene earlier if necessary.

Risk factors for necrotizing enterocolitis in preterm infants: a Meta analysis

OBJECTIVES

To systematically evaluate the risk factors for necrotizing enterocolitis (NEC) in preterm infants.

METHODS

PubMed, Embase, Cochrane Library, China National Knowledge Infrastructure, and Wanfang Data were searched for case-control studies and cohort studies on the risk factors for NEC in preterm infants published up to December 2021. RevMan 5.3 software was used to perform the Meta analysis.

RESULTS

A total of 38 studies were included (28 case-control studies and 10 cohort studies). The Meta analysis showed that maternal gestational diabetes (OR=2.96, P<0.001), intrahepatic cholestasis during pregnancy (OR=2.53, P<0.001), preeclampsia (OR=1.73, P=0.020), history of neonatal asphyxia (OR=2.13, P<0.001), low gestational age (OR=1.23, P=0.010), sepsis (OR=5.32, P<0.001), patent ductus arteriosus (OR=1.57, P=0.001), congenital heart disease (OR=3.78, P<0.001), mechanical ventilation (OR=2.23, P=0.020), history of antibiotic use (OR=1.07, P<0.001), use of vasopressors (OR=2.34, P=0.040), and fasting (OR=1.08, P<0.001) were risk factors for NEC in preterm infants, while cesarean section (OR=0.73, P=0.004), use of pulmonary surfactant (OR=0.43, P=0.008), and breastfeeding (OR=0.24, P=0.020) were protective factors against NEC.

CONCLUSIONS

Maternal gestational diabetes, intrahepatic cholestasis during pregnancy, preeclampsia, low gestational age, fasting, sepsis, patent ductus arteriosus, congenital heart disease, and histories of asphyxia, mechanical ventilation, antibiotic use, and use of vasopressors may increase the risk of NEC in preterm infants, while cesarean section, use of pulmonary surfactant, and breastfeeding may decrease the risk of NEC in preterm infants.

The Recipient Epidemiology and Donor Evaluation Study-IV-Pediatric (REDS-IV-P): A research program striving to improve blood donor safety and optimize transfusion outcomes across the lifespan

BACKGROUND

The Recipient Epidemiology and Donor Evaluation Study-IV-Pediatric (REDS-IV-P) is a new iteration of prior National Heart, Lung, and Blood Institute (NHLBI) REDS programs that focus on improving transfusion recipient outcomes across the lifespan as well as the safety and availability of the blood supply.

STUDY DESIGN AND METHODS

The US program includes blood centers and hospitals (22 including 6 free-standing Children's hospitals) in four geographic regions. The Brazilian program has 5 participating hemocenters. A Center for Transfusion Laboratory Studies (CTLS) and a Data Coordinating Center (DCC) support synergistic studies and activities over the 7-year REDS-IV-P program.

RESULTS

The US is building a centralized, vein-to-vein (V2V) database, linking information collected from blood donors, their donations, the resulting manufactured components, and data extracts from hospital electronic medical records of transfused and non-transfused patients. Simultaneously, the Brazilian program is building a donor, donation, and component database. The databases will serve as the backbone for retrospective and prospective observational studies in transfusion epidemiology, transfusion recipient outcomes, blood component quality, and emerging blood safety issues. Special focus will be on preterm infants, patients with sickle cell disease, thalassemia or cancer, and the effect of donor biologic variability and component manufacturing on recipient outcomes. A rapid response capability to emerging safety threats has resulted in timely studies related to Severe Acute Respiratory Syndrome Corona Virus-2 (SARS-CoV-2).

CONCLUSIONS

The REDS-IV-P program endeavors to improve donor-recipient-linked research with a focus on children and special populations while also maintaining the flexibility to address emerging blood safety issues.

The short-term effects of RBC transfusions on intestinal injury in preterm infants

BACKGROUND

Anemic preterm infants may require red blood cell (RBC) transfusions to maintain sufficient oxygen supply to vital organs. Transfusion treatment, however, may have adverse intestinal effects. We aimed to investigate the short-term effects of RBC transfusions, hypothesizing to find signs of oxidative stress and intestinal injury, possibly related to levels of splanchnic (re-)oxygenation.

METHODS

We prospectively included preterm infants (gestational age < 32 weeks). We measured urinary biomarkers for oxidative stress (8-isoprostane) and intestinal cell injury (intestinal fatty acid-binding protein, I-FABP) shortly before and after RBC transfusion. Splanchnic oxygen saturation (r_sSO₂) and r_sSO₂ variability were assessed simultaneously.

RESULTS

Twenty-nine preterm infants received 58 RBC transfusions at various postnatal ages. Six of them developed necrotizing enterocolitis (NEC) after transfusion. Urinary 8-isoprostane and I-FABP increased following RBC transfusion (median 282-606 pg/ml and 4732-6968 pg/ml, p < 0.01), more pronounced in infants who developed NEC. Change in I-FABP correlated with change in 8-isoprostane (rho = 0.623, p < 0.01). Lower r_sSO₂ variability, but not higher mean r_sSO₂ was associated with higher 8-isoprostane and I-FABP levels after transfusion.

CONCLUSIONS

Preterm RBC transfusions are associated with concomitant signs of oxidative stress and intestinal injury, parallel with lower variability in splanchnic oxygenation. This may represent the early pathogenetic process of transfusion-associated NEC.

IMPACT

Red blood cell (RBC) transfusions in preterm infants are associated with a near 2-fold increase in urinary biomarkers for oxidative stress (8-isoprostane) and intestinal cell injury (intestinal fatty acid-binding protein, I-FABP). Magnitude of change in I-FABP strongly correlated with the magnitude of 8-isoprostane change, suggesting a role for oxidative stress in the pathogenesis of intestinal injury. Lower splanchnic oxygen saturation variability following RBC transfusion was associated with higher 8-isoprostane and I-FABP levels. Loss of splanchnic variability after RBC transfusion may result from increased oxidative stress and its concomitant intestinal injury, possibly representing the early pathogenetic process of transfusion-associated necrotizing enterocolitis.

Early versus late-onset necrotizing enterocolitis in very low birth infants in the neonatal intensive care unit

BACKGROUND

Necrotizing enterocolitis (NEC), one of the most severe emergencies in neonates, is a multifactorial disease with diverse risk factors.

OBJECTIVES

To compare between the clinical and laboratory characteristics of premature infants diagnosed with early-onset NEC (EO-NEC) and those with late-onset NEC (LO-NEC).

PATIENTS AND METHODS

Enrolled infants were identified from prospective local data collected for the Israel National very low birth weight (VLBW, < 1500 g) infant database and from the local electronic patient files data base for the period 1996-2017.

RESULTS

Overall, 95 VLBW infants (61, 64.21% EO-NEC and 34, 35.87% LO-NEC) were enrolled. EO-NEC infants had higher rate of IVH grade 3 and 4 (26.2% vs 2.9%, p = 0.005) and were more likely to undergo surgery (49.2% vs 26.5%, p = 0.031). LO-NEC infants had a higher incidence of previous bloodstream infections (35.3% vs 8.2%, p = 0.002) compared to EO-NEC. In multivariable analysis models, surgical intervention was associated with EO-NEC (OR: 4.627, p = 0.013) as well as PDA and positive blood culture prior to the NEC episode.

CONCLUSIONS

Our data support the hypothesis that EO-NEC has significant different clinical and microbiological attributes compared to LO-NEC.

Neonatal anemia relates to intestinal injury in preterm infants

BACKGROUND

Anemia is associated with decreased tissue oxygenation in preterm infants and may contribute to developing necrotizing enterocolitis (NEC). We aimed to investigate whether hemoglobin level is associated with intestinal injury, by comparing anemic infants 10 days prior to red blood cell (RBC) transfusion with non-anemic controls.

METHODS

A nested case-control study in which we matched anemic preterms (gestational age (GA) < 32 weeks) with non-anemic controls (1:1), based on GA, birth weight (BW), and postnatal age. We measured urinary intestinal fatty acid-binding protein, I-FABP, marker for intestinal injury, twice weekly. Simultaneously, we assessed splanchnic oxygen saturation (r_sSO₂) and r_sSO₂ variability.

RESULTS

Thirty-six cases and 36 controls were included (median GA 27.6 weeks, BW 1020 grams). Median I-FABP level was higher in cases from 6 days to 24-h before transfusion (median ranging: 4749-8064 pg/ml versus 2194-3751 pg/ml). R_sSO₂ and r_sSO₂ variability were lower in cases than controls shortly before transfusion. Hemoglobin levels correlated negatively with r_sSO₂ and r_sSO₂ variability in cases, and negatively with I-FABP in cases and controls together.

CONCLUSIONS

Urinary I-FABP levels were higher in anemic infants before RBC transfusion than in non-anemic matched controls, suggesting intestinal injury associated with anemia. This may predispose to NEC in some anemic preterm infants.

IMPACT

Anemia is a common comorbidity in preterm infants and may lead to impaired splanchnic oxygen saturation and intestinal tissue hypoxia, a proposed mechanism for NEC. Lower hemoglobin level is associated with higher urinary I-FABP levels, a marker for intestinal injury, both in anemic preterm infants and in cases and controls together. Lower splanchnic oxygen saturation and reduction of its variability are associated with higher urinary I-FABP levels in anemic preterm infants before their first RBC transfusion. These results support the hypothesis that anemia in very preterm infants results in intestinal cell injury, which may precede NEC development in some.

Necrotizing enterocolitis and mortality after transfusion of ABO non-identical blood

BACKGROUND

The relationship between ABO non-identical transfusion and the outcomes of necrotizing enterocolitis (NEC), and all-cause mortality in very-low birth weight (VLBW) neonates receiving red blood cell transfusion is unknown.

STUDY DESIGN AND METHODS

A retrospective multicenter cohort study was conducted in VLBW neonates in neonatal intensive care units between 2004 and 2016. VLBW (≤1500 grams) neonates were followed until discharge or in-hospital death. The primary exposure was ABO group. Secondary exposures included platelet count, plasma transfusions, and maternal ABO group. Outcome measures were NEC (defined as Bell stage ≥ 2) and all-cause mortality. Time-dependent Cox regression models with competing risks were used to investigate factors associated with NEC and mortality.

RESULTS

Thousand and sixteen neonates were included with 10.8% developing NEC (n = 110) and 14.1% mortality (n = 143). Platelet count (hazard ratio [HR] = 0.995; 95% confidence interval [CI]: 0.922-0.998) and number of plasma transfusions (HR = 2.908; 95% CI:1.265-6.682) were associated with NEC, while ABO group (non-O vs. O) was not (HR = 0.761; 95% CI: 0.393-1.471). Higher all-cause mortality occurred in neonates without NEC who were non-O compared with O (HR = 17.5; 95% CI: 1.784-171.692), but not in neonates with NEC (HR = 1.112; 95% CI: 0.142-8.841). Plasma transfusion was associated with increased mortality in both groups.

DISCUSSION

ABO non-identical transfusion was not associated with NEC or mortality in neonates with NEC. It was associated with increased mortality in neonates without NEC. As many neonatal intensive care units transfuse only O group blood as routine practice, future trials are needed to investigate the association between this practice and neonatal mortality.

Transfusion-associated necrotizing enterocolitis (NEC) in extremely preterm infants: experience of a tertiary neonatal center in UK

OBJECTIVE

To compare the characteristics and short-term outcomes in extremely preterm infants, who developed necrotizing enterocolitis (NEC) following a packed red blood cell transfusion (pRBC) within 48 h (TANEC), with those who developed NEC beyond 48 h (non-TANEC).

SETTING

A single-center retrospective cohort study in a Tertiary neonatal intensive care unit in the UK over a 5-year period.

PATIENTS AND METHODS

Extremely premature infants (23-27 weeks gestation) were selected. TANEC and non-TANEC incidence were calculated from the confirmed NEC group (defined as modified Bell's stage II and beyond). The characteristics and short-term outcomes of infants with TANEC in the first 8 weeks of life were compared to infants with non-TANEC.

RESULTS AND INTERPRETATION

Incidence of confirmed NEC was 14% (28/207). On further subgroup analysis of the confirmed NEC cases, 46% (13/28) of infants were identified with TANEC and 54% (15/28) with non-TANEC. The incidence of TANEC did not correlate with the number of antecedent pRBC transfusions or the pre-transfusion median hemoglobin (Hb) levels. There were no significant differences in characteristics between the TANEC and non-TANEC groups. Infants within the TANEC group required more intensive neonatal care support, greater surgical intervention (p-value 0.043) with loss of gut integrity and an increase in number of TPN dependency days (p-value 0.014).

CONCLUSIONS

A significantly worse clinical course and short-term outcome was observed in the TANEC group when compared with the non-TANEC group.

Effect of High-Dose Erythropoietin on Blood Transfusions in Extremely Low Gestational Age Neonates: Post Hoc Analysis of a Randomized Clinical Trial

IMPORTANCE

Extremely preterm infants are among the populations receiving the highest levels of transfusions. Erythropoietin has not been recommended for premature infants because most studies have not demonstrated a decrease in donor exposure.

OBJECTIVES

To determine whether high-dose erythropoietin given within 24 hours of birth through postmenstrual age of 32 completed weeks will decrease the need for blood transfusions.

DESIGN, SETTING, AND PARTICIPANTS

The Preterm Erythropoietin Neuroprotection Trial (PENUT) is a randomized, double-masked clinical trial with participants enrolled at 19 sites consisting of 30 neonatal intensive care units across the United States. Participants were born at a gestational age of 24 weeks (0-6 days) to 27 weeks (6-7 days). Exclusion criteria included conditions known to affect neurodevelopmental outcomes. Of 3266 patients screened, 2325 were excluded, and 941 were enrolled and randomized to erythropoietin (n = 477) or placebo (n = 464). Data were collected from December 12, 2013, to February 25, 2019, and analyzed from March 1 to June 15, 2019.

INTERVENTIONS

In this post hoc analysis, erythropoietin, 1000 U/kg, or placebo was given every 48 hours for 6 doses, followed by 400 U/kg or sham injections 3 times a week through postmenstrual age of 32 weeks.

MAIN OUTCOMES AND MEASURES

Need for transfusion, transfusion numbers and volume, number of donor exposures, and lowest daily hematocrit level are presented herein.

RESULTS

A total of 936 patients (488 male [52.1%]) were included in the analysis, with a mean (SD) gestational age of 25.6 (1.2) weeks and mean (SD) birth weight of 799 (189) g. Erythropoietin treatment (vs placebo) decreased the number of transfusions (unadjusted mean [SD], 3.5 [4.0] vs 5.2 [4.4]), with a relative rate (RR) of 0.66 (95% CI, 0.59-0.75); the cumulative transfused volume (mean [SD], 47.6 [60.4] vs 76.3 [68.2] mL), with a mean difference of -25.7 (95% CI, 18.1-33.3) mL; and donor exposure (mean [SD], 1.6 [1.7] vs 2.4 [2.0]), with an RR of 0.67 (95% CI, 0.58-0.77). Despite fewer transfusions, erythropoietin-treated infants tended to have higher hematocrit levels than placebo-treated infants, most noticeable at gestational week 33 in infants with a gestational age of 27 weeks (mean [SD] hematocrit level in erythropoietin-treated vs placebo-treated cohorts, 36.9% [5.5%] vs 30.4% [4.6%] (P < .001). Of 936 infants, 160 (17.1%) remained transfusion free at the end of 12 postnatal weeks, including 43 in the placebo group and 117 in the erythropoietin group (P < .001).

CONCLUSIONS AND RELEVANCE

These findings suggest that high-dose erythropoietin as used in the PENUT protocol was effective in reducing transfusion needs in this population of extremely preterm infants.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01378273.

Abnormal Splanchnic Regional Saturations in a Preterm Infant That Developed Necrotizing Enterocolitis Following a Red Blood Cell Transfusion

BACKGROUND

Necrotizing enterocolitis (NEC) has been associated with red blood cell (RBC) transfusions in preterm infants. Near-infrared spectroscopy (NIRS) can be used to noninvasively monitor regional oxygen saturations (rSO2).

CLINICAL FINDINGS

This former 28-week female premature infant, 29 days old, received an RBC transfusion due to increased apneic spells and a hematocrit of 27%. Within 24 hours she developed abdominal distension and passed a bloody stool (Bell's stage 2 NEC on abdominal x-ray). She completed 7 days of antibiotics and nothing-by-mouth status and was discharged home on room air and oral feedings on day of life 70.

PRIMARY DIAGNOSIS

We describe the presentation of NEC following a RBC transfusion in a preterm infant monitored with cerebral and splanchnic NIRS.

INTERVENTIONS

Mean rSO2 (cerebral and splanchnic) measurements were continuously recorded and calculated in 30-minute periods at baseline (prior to packed RBC transfusion), every hour during the RBC transfusion, and every 3 hours for the following 48 hours.

OUTCOMES

In this infant, average baseline splanchnic rSO2 was low at 46.5%, and increased during transfusion to 65%. However, following the RBC transfusion and an enteral feeding, splanchnic rSO2 dramatically decreased to 26%, and remained low until the time of NEC diagnosis.

PRACTICE RECOMMENDATIONS

To develop awareness of the increased risk for NEC in premature infants with significant anemia that receive packed RBC transfusions. With further studies and education, NIRS could be a valuable tool for the nurses and medical team to identify these at-risk neonates.

Association of Bolus Feeding With Splanchnic and Cerebral Oxygen Utilization Efficiency Among Premature Infants With Anemia and After Blood Transfusion

IMPORTANCE

The pathogenesis of transfusion-associated necrotizing enterocolitis remains elusive. Splanchnic hypoperfusion associated with packed red blood cell transfusion (PRBCT) and feeding has been implicated, but studies of splanchnic tissue oxygenation with respect to feeding plus PRBCT are lacking.

OBJECTIVE

To investigate the oxygen utilization efficiency of preterm gut and brain challenged with bolus feeding during anemia and after transfusion using near-infrared spectroscopy.

DESIGN, SETTING, AND PARTICIPANTS

This prospective cohort study conducted from September 1, 2014, to November 30, 2016, at a tertiary neonatal intensive care unit included 25 hemodynamically stable infants with gestational age less than 32 weeks, birth weight less than 1500 g, and postmenstrual age younger than 37 weeks. Data analysis was performed from August 1, 2017, to October 31, 2018.

EXPOSURES

Infants received PRBCT (15 mL/kg for 4 hours) and at least 120 mL/kg daily of second hourly bolus feedings.

MAIN OUTCOMES AND MEASURES

Splanchnic fractional tissue oxygen extraction (FTOEs) and cerebral fractional tissue oxygen extraction (FTOEc) measures were made during 75-minute feeding cycles that comprised a 15-minute preprandial feeding phase (FP0) and 4 contiguous 15-minute postprandial feeding phases (FP1, FP2, FP3, and FP4; each 15 minutes long). The intraindividual comparisons of feeding-related changes were evaluated during the pretransfusion epoch (TE0: 4 hours before onset of transfusion) and 3 TEs after transfusion (TE1: first 8 hours after PRBCT completion; TE2: 9-16 hours after PRBCT completion; and TE3: 17-24 hours after PRBCT completion).

RESULTS

Of 25 enrolled infants (13 [52%] female; median birth weight, 949 g [interquartile range {IQR}, 780-1100 g]; median gestational age, 26.9 weeks [IQR, 25.9-28.6 weeks]; median enrollment weight, 1670 g [IQR, 1357-1937 g]; and median postmenstrual age, 34 weeks [IQR, 32.9-35 weeks]), 1 infant was excluded because of corrupted near-infrared spectroscopy data. No overall association was found between FTOEs and FPs in a multivariable repeated-measures model that accounted for transfusion epochs (primary analysis approach) (FP0: mean estimate, 11.64; 95% CI, 9.55-13.73; FP1: mean estimate, 12.02; 95% CI, 9.92-14.11; FP2: mean estimate, 12.77; 95% CI, 10.68-14.87; FP3: mean estimate, 12.54; 95% CI, 10.45-14.64; FP4: mean estimate, 12.98; 95% CI, 10.89-15.08; P = .16 for the FP association). However exploratory analyses of postprandial changes in FTOEs undertaken for each transfusion epoch separately found evidence of increased postprandial FTOEs during TE1 (mean [SD] FTOEs, 10.55 [5.5] at FP0 vs 13.21 [5.96] at FP4, P = .046). The primary and exploratory analyses found no association between FTOEc and feeding phases, suggesting that cerebral oxygenation may be protected.

CONCLUSIONS AND RELEVANCE

The findings suggest that enteral feeding may be associated with gut ischemia and potentially transfusion-associated necrotizing enterocolitis. The postprandial changes in FTOEs appear to warrant further investigation in larger randomized studies.

Stopping enteral feeds for prevention of transfusion-associated necrotising enterocolitis in preterm infants

BACKGROUND

Feeding practices around the time of packed red blood cell transfusion have been implicated in the subsequent development of necrotising enterocolitis (NEC) in preterm infants. Specifically, it has been suggested that withholding feeds around the time of transfusion may reduce the risk of subsequent NEC. It is important to determine if withholding feeds around transfusion reduces the risk of subsequent NEC and associated mortality.

OBJECTIVES

• To assess the benefits and risks of stopping compared to continuing feed management before, during, and after blood transfusion in preterm infants • To assess the effects of stopping versus continuing feeds in the following subgroups of infants: infants of different gestations; infants with symptomatic and asymptomatic anaemia; infants who received different feeding schedules, types of feed, and methods of feed delivery; infants who were transfused with different blood products, at different blood volumes, via different routes of delivery; and those who received blood transfusion with and without co-interventions such as use of diuretics • To determine the effectiveness and safety of stopping feeds around the time of a blood transfusion in reducing the risk of subsequent necrotising enterocolitis (NEC) in preterm infants SEARCH METHODS: We used the standard search strategy of Cochrane Neonatal to search the Cochrane Central Register of Controlled Trials (CENTRAL; 2018, Issue 11), in the Cochrane Library; MEDLINE (1966 to 14 November 2018); Embase (1980 to 14 November 2018); and the Cumulative Index to Nursing and Allied Health Literature (CINAHL; 1982 to 14 November 2018). We also searched clinical trials databases, conference proceedings, and reference lists of retrieved articles for randomised controlled trials (RCTs), cluster-RCTs, and quasi-RCTs.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials that compared stopping feeds versus continuing feeds around the time of blood transfusion in preterm infants.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials, assessed trial quality, and extracted data from the included studies.

MAIN RESULTS

The search revealed seven studies that assessed effects of stopping feeds during blood transfusion. However, only one RCT involving 22 preterm infants was eligible for inclusion in the review. This RCT had low risk of selection bias but high risk of performance bias, as care personnel were not blinded to the study allocation. The primary objective of this trial was to investigate changes in mesenteric blood flow, and no cases of NEC were reported in any of the infants included in the trial. We were unable to draw any conclusions from this single study. The overall GRADE rating for quality of evidence was very low.

AUTHORS' CONCLUSIONS

Randomised controlled trial evidence is insufficient to show whether stopping feeds has an effect on the incidence of subsequent NEC or death. Large, adequately powered RCTs are needed to address this issue.

Impact of red blood cell transfusions on intestinal barrier function in preterm infants

OBJECTIVE

To determine the relationships of red blood cell (RBC) transfusion and enteral feeding to changes in intestinal permeability (IP) measured by the relative intestinal uptake of lactulose (La) and rhamnose (Rh) in preterm infants <33 wk gestation.

DESIGN/METHODS

Infants 240-326wk gestation received La/Rh solution enterally on study days 1, 8 and 15.Urinary La/Rh ratio was measured by HPLC. Hematocrit preceding transfusion, total RBC transfusion volume, volume/kg, and feeding status during each study interval (birth-d1; d1-d8, and d8-d15) were determined.

RESULTS

Of the seventeen (40.5%) subjects who received≥1 transfusion during the study period, 12 (70.6%) infants were <28 wk gestation and 5 (29.4%) infants were≥28 wk gestation, p < 0.0001. Lower pre-transfusion hematocrit was observed in intervals preceding high IP (La/Rh > 0.05) than in intervals preceding low IP (La/Rh≤0.05) measurements (33 vs 35.8, p = 0.1051). RBC transfusions occurred more frequently in intervals preceding high IP than in intervals preceding low IP (26.8%; vs 8.3%, p = 0.0275) with 5-fold higher total RBC volume and volume/kg in intervals preceding any time point with high IP. RBC transfusion during an interval was associated with a three-fold increased risk of high IP (aOR 2.7; 95% C.I 0.564-12.814; p = 0.2143). Exclusive breast milk exposure and post-menstrual age reduced the risk for high IP following RBC transfusion.

CONCLUSIONS

Both RBC transfusion number and volume was associated with subsequent high IP measurements in preterm infants <33 weeks gestation and potentially may contribute to impairment of the preterm intestinal barrier.

A murine neonatal model of necrotizing enterocolitis caused by anemia and red blood cell transfusions

Necrotizing enterocolitis (NEC) is an idiopathic, inflammatory bowel necrosis of premature infants. Clinical studies have linked NEC with antecedent red blood cell (RBC) transfusions, but the underlying mechanisms are unclear. Here we report a neonatal murine model to investigate this association. C57BL/6 mouse pups rendered anemic by timed phlebotomy and then given RBC transfusions develop NEC-like intestinal injury with prominent necrosis, inflammation, and submucosal edema/separation of the lamina propria in the ileocecal region and colon within 12-24 h. The anemic intestine is infiltrated by inflammatory macrophages, which are activated in situ by RBC transfusions via a Toll-like receptor (TLR)-4-mediated mechanism and cause bowel injury. Chelation of RBC degradation products with haptoglobin, absence of TLR4, macrophage depletion, and inhibition of macrophage activation is protective. Intestinal injury worsens with increasing severity and the duration of anemia prior to transfusion, indicating a need for the re-evaluation of current transfusion guidelines for premature infants.

Feeding during transfusion and the risk of necrotizing enterocolitis in preterm infants

OBJECTIVE

To evaluate the effect of withholding feeds during transfusion on transfusion associated acute gut injury (TRAGI).

STUDY DESIGN

Data were collected on 125 preterm infants before and after the practice of withholding feeds for 12-24 h during transfusion was instituted. Logistic regression was used to examine effects of withholding feeds on TRAGI rates.

RESULTS

A total of 19 (15%) infants developed NEC; 6/19 (32%) had TRAGI. Postnatal hydrocortisone use was associated with TRAGI (OR 8.97; 95% CI 1.17-68.46, p = 0.034). There was no difference in NEC rates (15.8 vs. 14.7%) and the proportions (22.2 vs. 40%) of TRAGI in the two time periods before and after instituting the standardized feeding regimen and practice of holding feeds during transfusion.

CONCLUSION

No significant decrease was noted in the rates of TRAGI after feeds were withheld during transfusion. Further studies are warranted to explore the relationship between feeds during transfusion and NEC.

Risk of Necrotizing Enterocolitis Following Packed Red Blood Cell Transfusion in Very Low Birth Weight Infants

OBJECTIVE

To evaluate the association between red blood cell (RBC) transfusion leading to necrotizing enterocolitis (NEC) within 48 h, known as transfusion-associated necrotizing enterocolitis (TANEC).

METHODS

A nested case-control study using historical data was conducted in the neonatal intensive care unit of Songklanagarind Hospital, Thailand. All very low birth weight (VLBW) infants delivered between November 2009 and July 2016 were enrolled. The infants were identified as RBC transfusion received and NEC developed. Logistic regression was used to evaluate risk factors for transfusion and the association between RBC transfusion and NEC.

RESULTS

Four hundred and forty-four VLBW infants were enrolled in the study. The median (interquartile range) gestational age was 29 (27, 31) wk. The overall incidence of NEC was 13%. Three (5.2%) of the NEC infants had TANEC. The infants who received RBC transfusion had a lower gestational age [odds ratio, OR 0.64; 95% confidence interval (95%CI) 0.57, 0.73, p < 0.001] and were more likely to have pneumonia (OR 9.86; 95%CI 5.02, 19.35, p < 0.001) or to have received H2 blocker (OR 2.92; 95%CI 1.73, 4.93, p < 0.001). The ORs (95% CI) after adjusting for confounders, the association between RBC transfusion and NEC for transfusions ≤2 d, >2 to 4 d, and > 4 to 6 d prior to NEC were 1.83 (0.41, 8.16; p = 0.43), 1.7 (0.26, 11.16; p = 0.58) and 1.19 (0.31, 4.62; p = 0.80) respectively.

CONCLUSIONS

After controlling of confounders, no evidence of association was found between RBC transfusion and TANEC.

Association between hemoglobin concentrations at discharge from the neonatal intensive care unit with markers of neurodevelopmental outcomes in premature neonates

BACKGROUND

Premature neonates are often subjected to multiple transfusions with red blood cells during their hospitalization in the neonatal intensive care unit (NICU). The hemoglobin threshold for transfusion prior to discharge from the NICU varies significantly among different centers. The aim of the present study is to investigate the association between hemoglobin concentration at discharge with neurodevelopmental outcomes in premature neonates.

METHODS

Retrospective observation study with regression analysis was performed with follow up assessment in the neuro-developmental outpatient clinic at 30 months of adjusted age.

RESULTS

Data from 357 neonates born at less than 37 weeks' gestation were analyzed. Sensory and motor neurodevelopment at 30 months of adjusted age, were not associated with the hemoglobin concentration at discharge (p=0.5891 and p=0.4575, respectively). There was no association between the hemoglobin concentration at discharge with fine or gross motor development (p=0.1582 and p=0.3805, respectively). Hemoglobin concentration at discharge was not associated with poor neurodevelopmental outcomes up until 30 months of adjusted age.

CONCLUSIONS

The data of the present study indicate that the hemoglobin concentration of premature neonates at the time of discharge is not associated with poorer markers of neurodevelopmental outcomes at 30 months of adjusted age. Comorbidities such as BPD and IVH that are present to premature neonates were identified as potential risk factors for certain aspects of the neurodevelopment.

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

This article summarizes available evidence on the relationship between red blood cell transfusion and anemia, and necrotizing enterocolitis (NEC). We review recent studies that highlight the uncertainty of the effect of red blood cell transfusion on NEC and the potential role of anemia. We also discuss potential pathophysiologic effects of both red blood cell transfusion and anemia and highlight strategies to prevent anemia and red blood cell transfusion. We also discuss ongoing randomized trials that are likely to provide important new evidence to guide red blood cell transfusion practices.

Transfusion-associated necrotizing enterocolitis in preterm infants: an updated meta-analysis of observational data

BACKGROUND

The number of observational studies that report an association between packed red blood cell (PRBC) transfusions and necrotizing enterocolitis (NEC) has increased. The primary objective of this study was to evaluate the association between PRBC transfusions and NEC in observational studies.

METHODS

Medline, Embase and Cochrane Library databases as well as the Pediatrics Academic Societies abstract archives were systematically searched to identify observational studies that investigated the association between PRBC transfusions and NEC. Key search terms included premature infant, blood transfusion and necrotizing enterocolitis. The generic inverse variance method with a random-effects model was used to meta-analyze selected studies. Odds ratios (ORs) and confidence intervals (CIs) were calculated.

RESULTS

A meta-analysis of 17 observational studies that reported the association between PRBC transfusions and NEC was performed. The meta-analysis revealed no evidence of an association between PRBC transfusions and a higher risk of NEC (OR: 0.96; 95% CI: 0.53-1.71; P=0.88). The effect estimates that suggested an association between PRBC transfusion and NEC in matched case-control studies (OR: 1.20; 95% CI: 0.58-2.47; P=0.63) differed from those reported in cohort studies (OR: 0.51; 95% CI: 0.34-0.75; P=<0.01).

CONCLUSIONS

This updated meta-analysis of predominantly low-to-moderate quality observational studies suggests that there is no significant association between PRBC transfusions and NEC. A higher quality of evidence on this topic is needed.

Characteristics and incidence of transfusion-associated necrotizing enterocolitis in the UK

Background and aims: The etiology of necrotizing enterocolitis (NEC) is unclear and postulated as being multifactorial. It has been suggested that one causative factor is the transfusion of packed red blood cells (PRBCs) leading to the disease entity commonly referred to as transfusion-associated NEC (TANEC). TANEC has been reported in North America but its incidence has not been formally investigated in the UK. Our aims were to identify the incidence of NEC and TANEC in tertiary-level UK neonatal units and to describe characteristics of TANEC cases.Materials and methods: Using strict case definitions for NEC and TANEC, we undertook a retrospective review to estimate the incidence of TANEC cases occurring in four UK tertiary-level centers during a 38-month period.Results: Of 8007 consecutive neonatal admissions of all gestations to the four centers, 68 babies went on to develop NEC and all affected infants were of very low birth weight (VLBW); 34 of these had previously received a transfusion of PRBCs but did not fit the diagnostic criteria for TANEC, whereas 15 (22%) of the 68 babies with NEC qualified as TANEC cases. UK cases occurred at an earlier postnatal age than cases reported in multiple large North American series and were of a lower birth weight.Conclusions: We have confirmed the presence of TANEC in the UK VLBW neonatal population. Its incidence lies within the wide range described in previous reports of this phenomenon globally, though with some local variation in characteristics. Further work is needed to clarify causation, pathophysiology, and possible mechanisms of prevention of TANEC.

Transfusion practice in neonates

Neonates, especially extremely low birth weight infants, are among the groups of patients undergoing transfusion frequently. Since they are exposed to higher specific transfusion risks compared to the patients of other age groups, there are many special aspects that must be considered for transfusion therapy in neonates. The transfusion risks in neonates include adverse outcomes specific for preterm infants as well as increased metabolic, immunologic, and infectious complications. To reduce the risks of transfusion-transmitted cytomegalovirus infection and transfusion-associated graft-versus-host disease, leukoreduced and irradiated cellular blood products should be used for all neonates. This review summarizes the risks of neonatal transfusion therapy, specific methods to reduce risk, and current trends and practices of red blood cell and platelet transfusions in neonates, to facilitate decision-making for neonatal transfusion.

Transfusion-associated necrotizing enterocolitis re-evaluated: a systematic review and meta-analysis

CONTEXT

Significant controversy exists surrounding the possible association between recent packed red blood cell (PRBC) transfusion and the subsequent development of necrotizing enterocolitis (NEC) in infants. Previous studies and meta-analyses reporting a statistically significant association led to a practice change to withhold enteral feeds in the peri-transfusion period in many centers in an effort to prevent NEC; however, results from more recent studies do not support the existence of an association and, thus, question the validity of this practice change.

OBJECTIVE

This study aimed to perform a systematic review and meta-analysis to determine whether exposure to recent PRBC transfusion (defined as within 48 h) is associated with the subsequent development of NEC stage ≥II (Bell's criteria) in infants.

METHODS

Medline, Embase, CINAHL, and the Cochrane Library were searched from inception to October 7, 2015. A gray literature search was also performed. Studies comparing the risk of NEC in infants exposed and unexposed to recent PRBC transfusion were included. Thirteen studies met eligibility criteria, and 10 (n=15,675 infants) were included in the meta-analysis. Three authors independently extracted data, and meta-analysis was performed using a random effects model.

RESULTS

We found a statistically significant 45% reduction in the unadjusted odds of NEC in infants exposed to a recent PRBC transfusion (odds ratio=0.55, 95% confidence interval=0.31-0.98).

CONCLUSION

Our results show a protective effect of recent PRBC transfusion on the subsequent development of NEC. The practice of withholding enteral feeds during the peri-transfusion period should be re-evaluated in light of these results.

Does red blood cell irradiation and/or anemia trigger intestinal injury in premature infants with birth weight ≤ 1250 g? An observational birth cohort study

BACKGROUND

Necrotizing enterocolitis (NEC) is a leading cause of neonatal morbidity and mortality in premature infants. To date, no effective biomarkers exist to predict which premature infants will develop NEC, limiting targeted prevention strategies. Multiple observational studies have reported an association between the exposure to red blood cell (RBC) transfusion and/or anemia and the subsequent development of NEC; however, the underlying physiologic mechanisms of how these factors are independently associated with NEC remain unknown.

METHODS

In this paper, we outline our prospective, multicenter observational cohort study of infants with a birth weight ≤ 1250 g to investigate the associations between RBC transfusion, anemia, intestinal oxygenation and injury that lead to NEC. Our overarching hypothesis is that irradiation of RBC units followed by longer storage perturbs donor RBC metabolism and function, and these derangements are associated with paradoxical microvascular vasoconstriction and intestinal tissue hypoxia increasing the risk for injury and/or NEC in transfused premature infants with already impaired intestinal oxygenation due to significant anemia. To evaluate these associations, we are examining the relationship between prolonged irradiation storage time (pIST), RBC metabolomic profiles, and anemia on intestinal oxygenation non-invasively measured by near-infrared spectroscopy (NIRS), and the development of NEC in transfused premature infants.

DISCUSSION

Our study will address a critical scientific gap as to whether transfused RBC characteristics, such as irradiation and metabolism, impair intestinal function and/or microvascular circulation. Given the multifactorial etiology of NEC, preventative efforts will be more successful if clinicians understand the underlying pathophysiologic mechanisms and modifiable risk factors influencing the disease.

TRIAL REGISTRATION

Our study is registered in ClinicalTrials.gov Identifier: NCT02741648 .

Anemia, red blood cell transfusions, and necrotizing enterocolitis

In the past 15 years, multiple clinical studies have identified a temporal association between red blood cell (RBC) transfusions and necrotizing enterocolitis (NEC). With some variability, most of these studies indicate that up to one-third of all cases of NEC involving very low-birth weight infants may occur within 24-48h after receiving a RBC transfusion. There is also evidence that the risk of such transfusion-associated NEC may be higher in infants transfused with the greatest severity of anemia. In this article, we summarize the clinical evidence pertaining to these issues; specifically, the contribution of RBC transfusions, and the contribution of severity of underlying anemia, to the pathogenesis of a type of NEC potentially termed, "transfusion/anemia-associated NEC."

Slow enteral feeding decreases risk of transfusion associated necrotizing enterocolitis

BACKGROUND

Necrotizing Enterocolitis (NEC) is a multifactorial condition where PRBC transfusion is associated with necrotizing enterocolitis (TANEC) in about a third of all cases of NEC. We have investigated the role of feeding practices in incidence of TANEC. We sought to compare infants diagnosed with TANEC versus infants diagnosed with classic NEC and investigated the effects of a standardized slow enteral feeding (SSEF) protocol on TANEC incidence as well as the effects of SSEF on growth of infants with NEC.

METHODS

We conducted a retrospective cohort study, where medical records of infants born in a tertiary care neonatal intensive care unit (level IIIb) from January 1997 to May 2014 with birth weight < 1500 grams and gestational age≤34 weeks with NEC stage IIa or greater according to the modified Bell's staging were reviewed.

RESULTS

During the study period, 111 infants developed NEC, and 41/111 (37%) were diagnosed with TANEC. Infants with TANEC were smaller, more premature, had higher SNAPPE scores and were more anemic prior to transfusion compared with infants with 'classic NEC'. The severity of NEC did not differ between the two groups, however, infants with TANEC had worse outcomes and longer NICU stays. Introduction of SSEF protocol, led to a significant decrease in TANEC. There was no difference in weight and head circumference of infants in the two groups at 2 years corrected age.

CONCLUSION

SSEF led to a significant reduction in the incidence of TANEC without impairing growth at 2 years corrected age.

Red Blood Cell Transfusion in Preterm Infants: Current Evidence and Controversies

The current evidence regarding the indication, advantages and risks of red blood cell transfusion (RBCT) for preterm infants is discussed. This is an important area in Neonatology to be examined given that 90% of extremely low birth weight infants receive RBCT and many controversies remain regarding when to transfuse and the risks of RBCT. The various treatment thresholds and guidelines used are presented and we compare the short-term clinical benefits of liberal and restrictive RBCT in preterm infants; the majority of these are equivocal and sadly long-term outcome data is limited. The latest evidence on how anaemia and blood transfusion affect organ perfusion in preterm infants is presented. This is important when trying to establish the optimal trigger threshold for RBCT in preterm infants, especially because the knowledge about the adaptive physiological responses to anaemia in very low birth weight infants and the effects of RBCT at various levels of anaemia is also inadequate. Further research into the physiological adaptive response to anaemia of varying degrees and to RBCT at different levels of anaemia in preterm infants of different gestational and post-natal ages is needed before we can conclusively guide the optimal timing and trigger thresholds for RBCT in preterm infants.

Splanchnic-Cerebral Oxygenation Ratio Decreases during Enteral Feedings in Anemic Preterm Infants: Observations under Near-Infrared Spectroscopy

BACKGROUND

Anemia is common in premature infants. Due to risks with red blood cell transfusions, many anemic infants are not transfused. The implications of this pathophysiologic status, especially at times of increased metabolic demand (enteral feedings), is not well understood. Near-infrared spectroscopy (NIRS) allows for the noninvasive determination of regional oxygen saturations (rSO2) in tissues such as the brain and mesentery, giving insight into their oxygen sufficiency.

OBJECTIVE

We tested the hypothesis that during enteral feedings very low birth weight (VLBW) infants with a hematocrit ≤28% will experience a decrease in splanchnic rSO2 and splanchnic-cerebral oxygenation ratio (SCOR).

METHODS

This prospective, observational, 2-centered study included VLBW infants receiving full enteral feedings with a hematocrit ≤28%. Cerebral and splanchnic rSO2 were monitored via NIRS for 24 h. Average values were calculated for periods immediately preceding, during, and after each feeding. SCOR was calculated from these values (rSO2 splanchnic/rSO2 cerebral), and data were analyzed using a linear mixed effect model.

RESULTS

Fifty neonates with a median gestational age of 28 weeks (range 23-32), a birth weight of 1,118 ± 284 g (mean ± SD), and a hematocrit of 26 ± 2% (mean ± SD) were studied. During feedings, SCOR decreased significantly from baseline (0.72 ± 0.17 to 0.69 ± 0.17, p = 0.043). With feedings, there was a trend of decreased splanchnic rSO2 (47 ± 11 to 45 ± 10, p = 0.057) and no change in cerebral rSO2 (66 ± 8 to 66 ± 7, p = 0.597).

CONCLUSIONS

VLBW infants with a hematocrit ≤28% had a decrease in SCOR and a trend towards decreased splanchnic rSO2 with enteral feedings.

Assessment of Mesenteric Tissue Saturation, Oxygen Saturation, and Heart Rate Pre- and Post-Blood Transfusion in Very Low-Birth-Weight Infants Using Abdominal Site Near-Infrared Spectroscopy

BACKGROUND

Preterm infants often receive blood transfusions during hospitalization. Although transfusions are intended to enhance oxygen delivery, previous studies found decreases in tissue and mesenteric oxygen saturation during and after blood transfusions without changes in vital signs and hemoglobin oxygen saturation.

PURPOSE

To study the effect of blood transfusions on regional mesenteric tissue oxygen saturation (rSO2), hemoglobin saturation of oxygen (SpO2), and heart rate (HR) in premature infants.

METHOD

A prospective, observational, nonrandomized study using a repeated-measures design was done to evaluate changes in physiologic variables (HR, SpO2, rSO2) before, during, and after a blood transfusion in premature infants.

RESULTS

A convenience sample of 30 infants with a mean gestational age of 25.5 (2.1) weeks was recruited. Repeated-measures analysis of variance found no significant differences in HR (P = .06) and SpO2 (P = .55) over time. However, significant differences occurred in rSO2 over the 3 time periods (P < .001). The rSO2 increased during the transfusion from 40.3% to 41.5%, but decreased to 34.9% in the posttransfusion period. Pairwise comparisons revealed statistically significant mean rSO2 differences between pretransfusion and posttransfusion (P < .001), and during transfusion to posttransfusion (P < .001) periods.

IMPLICATIONS FOR RESEARCH

This study supports previous findings of perfusion changes during blood transfusions in preterm infants.

IMPLICATIONS FOR PRACTICE

Measuring mesenteric tissue oxygenation during blood transfusion in very low-birth-weight infants can potentially add another physiologic parameter to guide further clinical assessment and interventions during transfusions.

The relationship of red blood cell transfusion to intestinal mucosal injury in premature infants

OBJECTIVE

To determine the incidence of intestinal mucosal injury before and after transfusions in premature infants.

STUDY DESIGN

Urine was collected throughout the hospital stay of 62 premature infants and specimens obtained within 24h before and after transfusion were assayed for intestinal fatty acid binding protein (iFABP). A urinary iFABP:creatinine ratio (iFABP_u:Cr_u) of 2.0pg/nmol was considered elevated.

RESULT

Forty-nine infants were transfused. iFABPu:Cru was elevated following 71 (75.6%) of 94 transfusions for which urine was available. In 51 (71.8%) of these, iFABPu:Cru was also elevated prior to the transfusion. Among four cases of transfusion-associated NEC, iFABP_u was elevated following every sentinel transfusion and prior to three of them.

CONCLUSION

Subclinical intestinal mucosal injury is frequent following blood transfusions in premature infants and, when present, usually precedes transfusion. This suggests that transfusion may not be a primary mediator of intestinal injury so much as anemia and its associated conditions.

LEVEL OF EVIDENCE

Prognosis study/level 3.

Red blood cell transfusions can induce proinflammatory cytokines in preterm infants

BACKGROUND

The risk of developing red blood cell (RBC) transfusion-associated necrotizing enterocolitis (TANEC) in preterm infants has recently been emphasized. Our aim was to assess changes in cytokine serum levels after RBC transfusions in a cohort of very preterm infants to evaluate their possible proinflammatory effect.

STUDY DESIGN AND METHODS

We carried out a prospective observational study. One transfusion event was studied in infants less than 32 weeks' gestation and more than 7 days old (n = 20) admitted to a tertiary neonatal intensive care unit. Interleukin (IL)-1β, IL-6, IL-8, tumor necrosis factor-α, interferon-γ (IFN-γ), IL-17, monocyte chemoattractant protein-1 (MCP-1), interferon-γ-induced protein 10 (IP-10), intracellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule serum levels were measured in enrolled patients within 120 minutes before (T₀ ) the RBC transfusion and then within 120 minutes (T₁ ), 12 ± 3 hours (T₂ ), 24 ± 6 hours (T₃ ), and 48 ± 6 hours (T₄ ) after the end of RBC transfusion.

RESULTS

Infants received 19.8 ± 3.0 mL of RBCs at the mean age of 50 ± 18 days. Their hematocrit level increased from 24.1 ± 1.2% to 39.4 ± 2.9%. IL-1β, IL-8, IFN-γ, IL-17, MCP-1, IP-10, and ICAM-1 increased significantly after RBC transfusions.

CONCLUSION

Proinflammatory cytokines are increased after RBC transfusion. These findings may contribute to explaining the pathogenesis of TANEC and suggest the opportunity of adopting wise transfusion guidelines that would help to avoid detrimental risks of transfusion-related immunomodulation and of undertransfusion.

Red blood cell transfusion in premature infants leads to worse necrotizing enterocolitis outcomes

BACKGROUND

Necrotizing enterocolitis (NEC) is a severe intestinal disease of premature infants with high mortality. Studies suggest a causative relationship between red blood cell (RBC) transfusion and NEC; however, whether RBC transfusion leads to worse outcomes in NEC is unknown. We sought to determine whether RBC transfusion was associated with an increased risk of surgical NEC and mortality.

METHODS

In this retrospective study, 115 patients were enrolled with NEC Bell's stage 2A or greater from 2010-2015. Patients were classified based on the timing of RBC transfusion before NEC: ≤72 h, >72 h, and no transfusion. Variables including gestational age (GA), birth weight (BW), feedings, and hematocrit levels were analyzed. Outcomes were surgical intervention for NEC following RBC transfusion and mortality.

RESULTS

Twenty-three (20%) infants developed NEC ≤ 72 h after RBC transfusion, 16 (69.6%) required surgery with a mortality rate of 21.7% (n = 5). Seventeen (15%) infants developed NEC > 72 h after RBC transfusion, 12 (70.6%) required surgery with a mortality rate of 23.5% (n = 4). 75 (65%) patients developed NEC without RBC transfusion, 17 (22.7%) required surgery with a mortality rate of 4% (n = 3). Lower GA and BW were significantly associated with RBC transfusion and the need for surgical intervention. RBC transfusion ≤72 h before NEC was associated with surgical NEC (pairwise adjusted P < 0.001) and mortality (pairwise adjusted P = 0.048). However, multivariable logistic regression analysis revealed RBC transfusion is not an independent risk factor for surgical NEC.

CONCLUSIONS

Infants of lower GA and BW were more likely to receive an RBC transfusion before NEC, which was significantly associated with surgical intervention and an increasing risk of mortality. Judicious use of transfusions in premature infants may improve NEC outcomes.

Should we believe in transfusion-associated enterocolitis? Applying a GRADE to the literature

Numerous observational studies appear to demonstrate an association between packed red blood cell (pRBC) transfusions and necrotizing enterocolitis (NEC). However, the limited numbers of randomized controlled trials (RCTs) do not support a causal relationship between pRBC transfusion and NEC. We sought to determine the quality of the evidence behind transfusion-associated necrotizing enterocolitis (TANEC), and to formulate a GRADE-based recommendation regarding transfusion practices to reduce the risk of TANEC. A systematic search including MEDLINE, Embase, CINAHL, the Cochrane Central Register of Controlled Trials and clinical trials registries was performed for studies assessing the association between transfusion and NEC. Teams of two paired reviewers independently screened studies for eligibility, assessed risk of bias using the GRADE framework, and collected data from each eligible study. We examined studies for two time points following transfusion: within 48h if this was available, and otherwise at any time after transfusion. In total, 23 observational studies and three RCTs met inclusion criteria. The average rating for the quality of evidence of individual studies was between "very low" and "low." On pooling studies for GRADE review, we observed an inconsistency of results. This led to a final overall quality of "very low" for the evidence for an association between transfusions and necrotizing enterocolitis. The pooled outcome of NEC for observational/case control studies was an odds ratio of 1.13 (95% CI: 0.99-1.29) when TANEC was defined as occurring within 48 hours of transfusion. For NEC occurring at any time post-transfusion, the pooled OR was 1.95 (1.60-2.38). Conversely, the pooled outcome of NEC for the RCT data had an odds ratio of 0.6 (0.3, 1.21) with NEC being less frequent in the liberal transfusion group compared to the restrictive transfusion group. The overall quality of the evidence for TANEC is "very low," suggesting very little confidence in the effect estimate. RCT data tended toward apparent protection against NEC. The available evidence is not sufficient to support a practice recommendation around pRBC transfusions in the context of preventing the development of NEC.

Blood transfusions, increased rates of surgical NEC, and lower survival: a propensity score-matched analysis

PURPOSE

We sought to investigate the association between blood transfusions (BT), rates of necrotizing enterocolitis requiring surgical intervention (SNEC), and survival.

METHODS

Blood transfusions in premature infants were identified in the Kids' Inpatient Database (2003-2009). Propensity score-matched analysis compared SNEC outcomes in BT vs. non-BT groups. Multivariate analyses were performed to determine independent predictors of outcome.

RESULTS

Overall, 663740 cases were identified and 4.9% received BT. Surgical necrotizing enterocolitis occurred in 493 cases in the BT group, while SNEC occurred in 1049 cases in the non-BT group. Propensity score analysis of 20991 BT and 20988 non-BT cases demonstrated higher SNEC rates with BT (odds ratio [OR], 1.21) vs non-BT. Surgical necrotizing enterocolitis with BT had lower survival rates (58%) vs non-BT (67%). Surgical necrotizing enterocolitis with BT had lower length of stay and total charges vs non-BT. On multivariate analyses, SNEC mortality with BT increased for lower gestational age, males (OR, 45.7), African Americans (OR, 64.4), and infants with cardiac anomalies (OR, 50.8) or bronchopulmonary dysplasia (OR, 177). Non-BT SNEC demonstrated higher mortality with lower gestational age and infants with bronchopulmonary dysplasia (OR, 6.56) or sepsis (OR, 3.66).

CONCLUSION

On propensity score-matched analysis, SNEC occurs at higher rates after BT and is associated with lower survival and lower resource utilization vs SNEC without BT.

Red blood cell transfusions increase fecal calprotectin levels in premature infants

OBJECTIVE

We hypothesized that red blood cell (RBC) transfusions influence intestinal inflammation in very low birth weight (VLBW) infants. We also suspected that hematocrit (Hct) at transfusions and RBC storage time correlate with intestinal inflammation.

STUDY DESIGN

VLBW infants, without major congenital defects, intestinal perforation or necrotizing enterocolitis, were enrolled prospectively. Fecal calprotectin (FC) levels were measured from stool samples collected before and after RBC transfusions. Data on Hct and RBC storage time were collected.

RESULT

Data from 42 RBC transfusions given to 26 infants revealed that FC levels increased faster than baseline after RBC transfusions (P=0.018) and were higher in multiple-transfused infants (0 to 48 and >48 h post transfusion, P=0.007 and P=0.005, respectively). Lower Hct and RBC storage >21 days correlated with higher FC levels (P=0.044 and P=0.013, respectively).

CONCLUSION

RBC transfusions, anemia and prolonged RBC storage were associated with an increase in intestinal inflammation.

Neonatal Transfusion Medicine: Five Major Unanswered Research Questions for the Twenty-First Century

Blood component transfusions are important to the care of preterm neonates; however, their use in clinical practice often is not based on high levels of evidence. Five major questions for neonates are discussed: (1) What is the optimal red blood cell (RBC) transfusion threshold? (2) What is the optimal platelet transfusion threshold? (3) Does the storage age of an RBC unit affect outcomes? (4) Does RBC transfusion contribute to the pathogenesis of necrotizing enterocolitis? and (5) Which new practices should be used to prevent transfusion-transmitted infections? Although definitive answers to these questions do not exist, future research should help answer them.

Decreased hazard of necrotizing enterocolitis in preterm neonates receiving red cell transfusions

BACKGROUND AND OBJECTIVES

Many observational studies reporting a temporal association between red cell transfusions (RBCTs) and necrotizing enterocolitis (NEC) in preterm infants fail to take into account RBCTs in infants without NEC. The objective of this study was to investigate the association between RBCTs and NEC in an analytical retrospective cohort study with minimization of selection and measurement bias and controlling for clinical covariates.

METHODS

Inborn preterm infants [23-32 weeks gestational age (GA)] without major congenital anomalies were eligible. Association of RBCT and modified Bell's Stage ≥2A NEC was explored using bivariate analyses and verified using multivariable Cox regression.

RESULTS

Of 627 eligible infants, 305 neither received RBCT nor developed NEC and 12 developed NEC prior to RBCT. Of 310 infants with RBCT, 27 developed NEC. Compared to infants without NEC, infants with NEC received significantly lower number of RBCTs before diagnosis of NEC (p = 0.000). On multivariable Cox regression controlling for clinical covariates, dichotomous RBCT exposure was associated with 60% reduced hazard for NEC.

CONCLUSIONS

RBCT exposure was associated with decreased hazards for NEC in preterm infants in this study; factors previously reported to be associated with NEC remained statistically significant predictors.

Why do four NICUs using identical RBC transfusion guidelines have different gestational age-adjusted RBC transfusion rates?

OBJECTIVE

To compare neonatal red blood cell (RBC) transfusion rates in four large Intermountain Healthcare NICUs, all of which adhere to the same RBC transfusion guidelines.

STUDY DESIGN

This retrospective analysis was part of a transfusion-management quality-improvement project. De-identified data included RBC transfusions, clinical and laboratory findings, the anemia-prevention strategies in place in each NICU, and specific costs and outcomes.

RESULT

Of 2389 NICU RBC transfusions given during the 4-year period studied, 98.9 ± 2.1% (mean ± S.D.) were compliant with our transfusion guidelines, with no difference in compliance between any of the four NICUs. However, RBC transfusion rates varied widely between the four, with averages ranging from 4.6 transfusions/1000 NICU days to 21.7/1000 NICU days (P < 0.00001). Gestational age-adjusted transfusion rates were correspondingly discordant (P < 0.00001). The lower-transfusing NICUs had written anemia-preventing guidelines, such as umbilical cord milking at very low birth weight delivery, use of cord blood for admission laboratory studies, and darbepoetin dosing for selected neonates. Rates of Bell stage ⩾ 2 necrotizing enterocolitis and grade ⩾ 3 intraventricular hemorrhage were lowest in the two lower-transfusing NICUs (P < 0.0002 and P < 0.0016). Average pharmacy costs for darbepoetin were $84/dose, with an average pharmacy cost of $269 per transfusion averted. With a cost of $900/RBC transfusion, the anemia-preventing strategies resulted in an estimated cost savings to Intermountain Healthcare of about $6970 per 1000 NICU days, or about $282,300 annually.

CONCLUSION

Using transfusion guidelines has been shown previously to reduce practice variability, lower transfusion rates and diminish transfusion costs. Based on our present findings, we maintain that even when transfusion guidelines are in place and adhered to rigorously, RBC transfusion rates are reduced further if anemia-preventing strategies are also in place.