Is “transfusion-associated necrotizing enterocolitis” an authentic pathogenic entity?

Transfusion-related acute gut injury: feeding, flora, flow, and barrier defense

TRAGI (transfusion-related acute gut injury) is an acronym we proposed to characterize a severe neonatal gastrointestinal reaction temporally related to a transfusion of packed blood red cells (PRBCs) for anemia in very low birth weights. The following are in support of a causative relationship: (1) the timing of necrotizing enterocolitis after a PRBC transfusion not being random, (2) traditional risk factors for necrotizing enterocolitis are often absent, (3) significant anemia appears to be a universal finding, (4) the age of donor blood is often slightly older than controls, (5) TRAGI is not postnatal age dependent, and (6) TRAGI does not show a centering at 31 weeks' postconceptual age as does nontransfusion-related NEC. Although TRAGI is linked to the timing of PRBC transfusions, we propose a novel hypothesis that the convergence at 31 weeks' postconceptual age for classic NEC approximates the age of presentation of other oxygen delivery and neovascularization syndromes (eg, retinopathy of prematurity), suggesting its etiologic link to a generalized systemic maturational mechanism or another common developmental theme. This report will begin by reviewing the history of the clinical presentation and discovery of TRAGI and will then analyze various pathophysiologic mechanisms that may account for the phenomenon when clinicians render therapies. We will end by a call to action for randomized clinical trials to test various etiologic theories.

Associations between "early" red blood cell transfusion and severe intraventricular hemorrhage, and between "late" red blood cell transfusion and necrotizing enterocolitis

Transfusion of banked donor erythrocytes can be life saving for small and ill neonates with severe anemia or active hemorrhage. However, risks of transfusions exist and must be weighed against potential benefits each time a transfusion is considered. The present review seeks to bring together the published data supporting 2 newly postulated risks of transfusions among very low-birth-weight neonates. The first is an association between "early" red blood cell transfusions, those administered in the first few days after birth, and the subsequent occurrence of a grade 3 or 4 intraventricular hemorrhage. The second is an association between "late" RBC transfusions and the subsequent occurrence of necrotizing enterocolitis. Much remains to be discovered about the pathogenetic links between transfusion and these adverse outcomes. Moreover, work is needed to clearly establish whether transfusions are causatively associated with these adverse outcomes or are covariables. The purpose of this chapter is to review the associations between transfusion and intraventricular hemorrhage and between transfusions and necrotizing enterocolitis and to use these associations to hypothesize that evidence-based improvements in transfusion practice have the potential to improve neonatal intensive care unit outcomes.

Transfusion-associated necrotising enterocolitis in very low birth weight premature infants

OBJECTIVE

Our aim was to determine the relationship between red blood cell transfusion and necrotising enterocolitis (NEC) in all admitted very low birth weight (VLBW) infants with or without transfusion.

STUDY DESIGN

All VLBW neonates were categorised into five groups: (i) subjects that developed NEC <48 h after transfusion (n = 15); (ii) subjects that developed NEC >48 h after transfusion (n = 31); (iii) subjects that were never transfused but developed NEC, (n = 50); (iv) subjects that were transfused but did not develop NEC, (n = 250) and (v) subjects that were neither transfused nor developed NEC (n = 301).

RESULTS

A group of 647 infants were enrolled in the study. Mean gestational age and birth weight of the patients were 29 ± 3.1 weeks and 1157 ± 237 g, respectively. The mean age at the onset of NEC in the NEC groups were 20 ± 2.3 days, 12 ± 3 days and 11 ± 2.6 days, respectively (P < 0.05). The mean interval from the last transfusion to the onset of NEC was 16.8 ± 8.8 h in group 1 and 240 ± 50 h in group 2 (P < 0.05).

CONCLUSION

In this study, we sought to evaluate all VLBW infants, whether they received a transfusion or not. We suggest that transfusion associated NEC exists, but many other factors influence this multifactorial disease. The age of NEC onset was later in transfused vs non-transfused patients, whereas the interval between transfusion and NEC was shorter in transfused vs non-transfused patients.

The 'Effects of Transfusion Thresholds on Neurocognitive Outcome of Extremely Low Birth-Weight Infants (ETTNO)' Study: Background, Aims, and Study Protocol

Background: Infants with extremely low birth weight uniformly develop anemia of prematurity and frequently require red blood cell transfusions (RBCTs). Although RBCT is widely practiced, the indications remain controversial in the absence of conclusive data on the long-term effects of RBCT. Objectives: To summarize the current equipoise and to outline the study protocol of the 'Effects of Transfusion Thresholds on Neurocognitive Outcome of extremely low birth-weight infants (ETTNO)' study. Methods: Review of the literature and design of a large pragmatic randomized controlled trial of restrictive versus liberal RBCT guidelines enrolling 920 infants with birth weights of 400-999 g with long-term neurodevelopmental follow-up. Results and Conclusions: The results of ETTNO will provide definite data about the efficacy and safety of restrictive versus liberal RBCT guidelines in very preterm infants.

The safety and efficacy of red cell transfusions in neonates: a systematic review of randomized controlled trials

Premature neonates commonly receive red blood cell (RBC) transfusions. This study systematically identified and appraised randomized controlled trials (RCTs) where the intervention was 'transfusion of red blood cells' from searches of multiple databases. Primary review outcomes were mortality, neurodevelopmental and respiratory endpoints. Two reviewers extracted data and assigned overall quality. Twenty-seven RCTs were identified and grouped into four predefined categories: trials comparing RBC transfusion versus no transfusion/placebo (n = 3); different thresholds for transfusion (n = 6); differing doses or administration schedule (n = 4), or different types or products of RBC (n = 14). In the threshold group of trials, enrolling 679 neonates, no significant differences in mortality (relative risk 1·22, 95% confidence interval 0·84-1·75) or chronic lung disease were found. Only two trials assessed neurodevelopment outcomes, both within the threshold group, but with differing results. The largest subgroup of RCTs by number evaluated different media for storage of red cells (n = 7), enrolling 221 neonates. The methodological quality of many RCTs was poor. The design of future RCTs can be informed by the lessons from this review. Many trials failed to report on outcomes that would be considered of primary importance to clinicians. Consistent reporting of adverse events is required, and endpoints need to include neurodevelopmental outcomes.

Necrotizing enterocolitis risk: state of the science

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

Fulminant necrotizing enterocolitis in a multihospital healthcare system

OBJECTIVE

A subset of necrotizing enterocolitis (NEC) cases is fulminant, characterized by rapid progression to death with massive bowel necrosis found at laparotomy or autopsy. We sought to identify and report all such cases in a multihospital healthcare system during the past 9 years and to characterize this entity using case-control methodologies.

STUDY DESIGN

This was a multicentered, cross-sectional, historic cohort study conducted using Intermountain Healthcare hospital patient data. All neonates who died of NEC within 48 h of onset, during 2001 to 2009, were compared with two matched control groups: (1) demographically matched controls who developed non-fulminant NEC, (2) demographically matched controls that did not develop NEC.

RESULT

During this period, 2 71 327 live births occurred in the Intermountain Healthcare hospitals. Of these, 318 had a diagnosis of NEC (Bell stage ≥II). Also during this period, 205 other neonates were transferred into an Intermountain hospital for treatment of NEC. Of these 523 NEC cases, 35 (6.7%) had a fulminant course. Compared with the non-fulminant cases, the fulminant group were born at lower weight (1088±545 vs 1652±817 g, P=0.000) and earlier gestational age (27.5±3.3 vs 31.1±4.4 weeks, P=0.000), and were more likely to have: (1) radiographic evidence of portal venous air (P=0.000), (2) hematocrit <22% (P=0.000), (3) increase in feeding volume >20 ml/kg/day (P=0.003), (4) immature to total (I/T) neutrophil ratio >0.5 (P=0.005), (5) blood lymphocyte count <4000/μl (P=0.018), (6) an increase in concentration of human milk fortifier within 48 h before developing NEC (P=0.020).

CONCLUSION

Portal venous air, anemia, rapid feeding escalation, a high I/T neutrophil ratio, a low lymphocyte count and recent increases in fortifier may all be associated with fulminant NEC.

Hematological interventions in NICU care: the use of rEpo, IVIG, and rG-CSF

This article focuses on the use of rEpo, IVIG, and rG-CSF in the NICU. It discusses the most recent studies and the most definitive and clinically relevant evidence, rather than summarizing all published studies. The last section was written for NICU practice groups that choose to use any of these medications and are seeking a consistent approach for doing so. The section provides the author's approach to the use of rEpo, IVIG, and rG-CSF, revealing personal preferences, interpretations, and experiences, and is based on the dictum, "if you are going to use it, use it the same way each time."

Transfusion associated necrotizing enterocolitis: a meta-analysis of observational data

BACKGROUND AND OBJECTIVES

Several studies have reported the possibility of an association between recent exposure to transfusion and development of necrotizing enterocolitis (NEC). Our objective was to systematically review and meta-analyze the association between transfusion and NEC (TANEC), identify predictors of TANEC, and the assess impact of TANEC on outcomes.

METHODS

Medline, Embase, CINAHL, and bibliographies of identified articles were searched for studies assessing association with recent (within 48 hours) exposure to transfusion and NEC. Two reviewers independently collected data and assessed the quality of the studies for bias in sample selection, exposure assessment, confounders, analyses, outcome assessments, and attrition. Meta-analyses were performed by using random effect model, and odds ratio and 95% confidence interval were calculated.

RESULTS

Eleven retrospective case-control studies and 1 cohort study of moderate risk of bias were included. Ten case-control studies had NEC not associated with transfusion as control patients (unmatched). Recent exposure to transfusion was associated with NEC. Neonates who developed TANEC were younger by 1.5 weeks, were of 528 g lower birth weight, were more likely to have patent ductus arteriosus, and were more likely receiving ventilatory support. TANEC infants had higher risk of mortality. Two pre-post comparative studies of 20 patients reported reduction of TANEC after withholding feeds during transfusion.

CONCLUSIONS

Recent exposure to transfusion was associated with NEC in neonates. Neonates who developed TANEC were at overall higher risk of NEC. TANEC patients were at higher risk of mortality, but additional studies adjusting for confounders are needed.

Clinical and research issues in neonatal anemia and thrombocytopenia

PURPOSE OF REVIEW

Anemia and thrombocytopenia are the most common hematological problems in neonates. Red blood cell (RBC) and platelet transfusions are the mainstays of therapy, but data to guide neonatal transfusion practices have been sparse. Recombinant hematopoietic growth factors represent another therapeutic alternative, but their use in this population requires a solid understanding of the developmental differences between fetal and adult hematopoiesis.

RECENT FINDINGS

Recently, follow-up studies from children randomized as neonates to either liberal or restrictive RBC transfusion approaches were published. Results of these studies have so far been contradictory and have generated more questions than answers. New developmental stage-specific problems associated with RBC transfusions were also uncovered, such as the transfusion-associated necrotizing enterocolitis. Finally, two thrombopoietin (Tpo) mimetics were approved by the FDA for the treatment of adults with chronic immune thrombocytopenia, thus offering a novel potential therapeutic alternative for thrombocytopenic neonates.

SUMMARY

In this review, we will discuss the currently available data regarding neonatal RBC and platelet transfusion thresholds, as well as the potential limitations, and concerns associated with the use of erythropoietin and Tpo mimetics in this patient population. Finally, we will point out specific areas wherein additional research is critically needed.

Risk factors for necrotizing enterocolitis totalis: a case-control study

OBJECTIVE

The objective of this study was to compare demographic and clinical events in three groups of preterm neonates: those with necrotizing enterocolitis totalis (NEC-T), those with NEC non-totalis (NEC non-T) and in preterm patients without NEC.

STUDY DESIGN

This retrospective case-control study was conducted at Yale New Haven Children's Hospital using patient data from January 1991 to December 2007. Study patients were less than 36 weeks of gestational age (GA) at birth, without gastrointestinal (GI) malformations. Cases (NEC-T) were diagnosed at operation or at autopsy with observation of >80% necrosis of the GI tract. Two control groups were assigned: Group 1 or NEC non-T and Group II or Non-NEC. Two to four controls per case were matched to cases by GA at birth±2 weeks. Demographic and clinical data for the day of diagnosis and retrospectively up to 7 days preceding diagnosis were recorded for those with NEC-T and NEC. Group II controls were matched for date of birth and day of life, in addition to GA at birth.

RESULT

A total of 14 075 patients were admitted to the Newborn Special Care Unit during the study interval. Overall 328 patients (2.3%) developed NEC≥Bell's Stage II; 39 patients met inclusion criteria for NEC-T case status; 148 NEC non-T and 110 non-NEC controls were assigned. In the comparison of NEC T and NEC non-T neonates, use of breast milk was associated with decreased risk of NEC-T, adjusted odds ratio (OR)=0.26, 95% confidence interval (CI) of OR=0.08-0.085, P=0.03. When NEC T and non-NEC patients were compared, having reached full-enteral feeds before the date of diagnosis of the matched case (adjusted OR=28.5, 95% CI of OR=2.7-299, P=0.005) and use of breast milk (adjusted OR=0.09, 95% CI of OR=0.02-0.56, P=0.01) were significantly different between the two groups.

CONCLUSION

Breast milk usage was significantly associated with decreased occurrence of NEC-T in our comparison of NEC-T, NEC non-T and non-NEC patients. Although there were some differences, the majority of demographic and clinical variables assessed were not shown to be significantly different between cases and controls. This highlights the need for more biological data in assessing risk of developing NEC-T.

Very low birth weight infants qualifying for a 'late' erythrocyte transfusion: does giving darbepoetin along with the transfusion counteract the transfusion's erythropoietic suppression?

OBJECTIVE

Red blood cell (RBC) transfusions can suppress erythropoiesis. On this basis, RBC transfusions administered to very low birth weight (VLBW) neonates potentially render them more likely to qualify for a subsequent transfusion.

STUDY DESIGN

We hypothesized that 'late' (>14 days after birth) RBC transfusions given to VLBW neonates result in a decrease in reticulocyte count persisting for at least 7 to 10 days. We also hypothesized that a single dose of darbepoetin given along with the transfusion would have the opposite effect, increasing the reticulocyte count for at least 7 to 10 days. To test this, we conducted a single-centered randomized trial with 20 VLBW neonates who, according to our transfusion guidelines, qualified for a late transfusion.

RESULT

VLBW infants about to receive a late RBC transfusion were randomized (1:1) to also receive vs not receive (controls) a single subcutaneous dose of darbepoetin (10 μg kg(-1)). Reticulocyte counts diminished significantly in the controls (a drop of 85±62 × 10(3) μl(-1) (mean±s.d.) at 7 to 10 days), but increased significantly in the darbepoetin recipients (an increase of 177±120 × 10(3) μl(-1) at 7 to 10 days, P<0.0001). At 7 to 10 days after the transfusion, hematocrits of the controls were 8.1±4.9 points above their pre-transfusion values and of the darbepoetin group were 12.4±2.7 points above their pre-transfusion values (P=0.033).

CONCLUSION

This was a limited-scope, single-centered, randomized trial intended to pilot-test a new concept in neonatal transfusion practice. Namely, we tested whether a late RBC transfusion suppressed reticulocytosis and whether a concomitant single dose of darbepoetin counteracted that suppression. Using the pilot data presented in this study, larger trials can now be designed to address meaningful clinical outcomes such as transfusion avoidance using this approach.

Increased odds of necrotizing enterocolitis after transfusion of red blood cells in premature infants

OBJECTIVES

To determine if infants with very low birth weight who receive packed red blood cell (PRBC) transfusions have increased odds of developing necrotizing enterocolitis (NEC), to determine the rate of NEC after PRBC transfusion, and to characterize the blood transfused preceding the onset of NEC.

STUDY DESIGN

A retrospective cohort design was used. The study population included infants with a birth weight of <1500 g who were from a single center. NEC after transfusion was defined as NEC that occurred in the 48 hours after initiation of PRBC transfusion. Statistical analysis included unadjusted and multivariable analyses.

RESULTS

The study sample included 2311 infants. A total of 122 infants (5.3%) developed NEC, and 33 (27%) of 122 NEC cases occurred after transfusion. NEC occurred after 33 (0.5%) of 6484 [corrected] transfusions. Infants who received a transfusion had increased adjusted odds (odds ratio: 2.3 [95% confidence interval: 1.2-4.2]) of developing NEC compared with infants who did not receive a transfusion. PRBCs transfused before NEC were predominantly (83%) from male donors and were a median of 5 days old.

CONCLUSIONS

In our study sample, PRBC transfusion was associated with increased odds of NEC. The rate of NEC after transfusion was 1.4%. From our data we could not determine if PRBC transfusions were part of the causal pathway for NEC or were indicative of other factors that may be causal for NEC.

Transfusion-related acute gut injury: necrotizing enterocolitis in very low birth weight neonates after packed red blood cell transfusion

OBJECTIVE

This is a repeat cohort study in which we sought to determine whether an association of necrotizing enterocolitis (NEC) <48 hours of a packed red blood cells (PRBC) transfusion was a prior sampling artifact.

STUDY DESIGN

All very low birth weight neonates with NEC Stage ≥ IIB admitted over an 18-month period were categorized for NEC: (1) <48 hours after a PRBC transfusion; (2) unrelated to the timing of PRBCs; and (3) never transfused.

RESULTS

Eight hundred eighty-three admissions over 18 months were reviewed; 256 were very low birth weight that resulted in 36 NEC cases and 25% were associated with PRBC (n = 9). PRBC-associated cases had lower birth weight, hematocrit, and rapid onset of signs (<5 hours). The timing of association of PRBC transfusion and NEC differed from random, showing a distribution that was not uniform over time (χ(2) = 170.7, df = 40; P < .000001) consistent with the possibility of a causative relationship in certain cases of NEC. Current weight at onset of NEC did not differ; however, the more immature the neonate the later the onset of NEC creating a curious centering of occurrence at a median of 31 weeks postconceptual age.

CONCLUSIONS

We conclude that PRBC-related NEC exists. Transfusion-related acute gut injury is an acronym we propose to characterize a severe neonatal gastrointestinal reaction proximal to a transfusion of PRBCs for anemia. The convergence at 31 weeks postconceptual age approximates the age of presentation of other O(2) delivery and neovascularization syndromes, suggesting a link to a generalized systemic maturational mechanism.

Red blood cell transfusion, feeding and necrotizing enterocolitis in preterm infants

OBJECTIVE

Preliminary studies suggested an association between red blood cell (RBC) transfusion and necrotizing enterocolitis (NEC) in premature neonates. An advantageous effect of withholding feeds during transfusion has never been studied. We aimed, first, to determine whether preterm infants who developed NEC were more likely to be transfused in the 48 to 72 h before the diagnosis of NEC; second, to test if a strict policy of withholding feeds during transfusion would decrease the incidence of transfusion-associated NEC.

STUDY DESIGN

The study was conducted in two phases. Phase 1: a retrospective case-control study of premature low-birth weight (<32 weeks and <2500 g) infants who developed NEC over a 6-year period. Phase 2: a comparison study of the incidence of NEC during the 18-months preceding, and the 18 months following the change of practice to withholding feeds during RBC transfusion.

RESULT

In the case-control study (25 infants with NEC and 25 controls), more infants in the NEC group received transfusions in the 48 and 72 h preceding diagnosis (56 vs 20% within 48 h, P=0.019; and 64 vs 24% within 72 h, P=0.01). The total number of transfusions and age of RBCs were not different between the two groups. Implementing the policy of withholding feeds during transfusion was associated with a decrease in the incidence of NEC from 5.3 to 1.3% (P=0.047).

CONCLUSION

Infants who developed NEC frequently received RBC transfusions in the 48 and 72 h preceding presentation of NEC. A strict policy of withholding feeds during transfusion may have a protective effect from NEC.

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

OBJECTIVE

To test the hypothesis that red blood cell (RBC) transfusions increase the risk of necrotizing enterocolitis (NEC) in premature infants, we investigated whether the risk of "transfusion-associated" NEC is higher in infants with lower hematocrits and advanced postnatal age.

STUDY DESIGN

Retrospective comparison of NEC patients and control patients born at < 34 weeks gestation.

RESULTS

The frequency of RBC transfusions was similar in NEC patients (47/93, 51%) and control patients (52/91, 58%). Late-onset NEC (> 4 weeks of age) was more frequently associated with a history of transfusion(s) than early-onset NEC (adjusted OR, 6.7; 95% CI, 1.5 to 31.2; P = .02). Compared with nontransfused patients, RBC-transfused patients were born at earlier gestational ages, had greater intensive care needs (including at the time of onset of NEC), and longer hospital stay. A history of RBC transfusions within 48-hours before NEC onset was noted in 38% of patients, most of whom were extremely low birth weight infants.

CONCLUSIONS

In most patients, RBC transfusions were temporally unrelated to NEC and may be merely a marker of overall severity of illness. However, the relationship between RBC transfusions and NEC requires further evaluation in extremely low birth weight infants using a prospective cohort design.