Predictive factors and practice trends in red blood cell transfusions for very-low-birth-weight infants

Thresholds for blood transfusion in extremely preterm infants: A review of the latest evidence from two large clinical trials

There are two recently completed large randomized clinical trials of blood transfusions in the preterm infants most at risk of requiring them. Liberal and restrictive strategies were compared with composite primary outcome measures of death and neurodevelopmental impairment. Infants managed under restrictive guidelines fared no worse in regard to mortality and neurodevelopment in early life. The studies had remarkably similar demographics and used similar transfusion guidelines. In both, there were fewer transfusions in the restrictive arm. Nevertheless, there were large differences between the studies in regard to transfusion exposure with almost 3 times the number of transfusions per participant in the transfusion of prematures (TOP) study. Associated with this, there were differences between the studies in various outcomes. For example, the combined primary outcome of death or neurodevelopmental impairment was more likely to occur in the TOP study and the mortality rate itself was considerably higher. Whilst the reasons for these differences are likely multifactorial, it does raise the question as to whether they could be related to the transfusions themselves? Clearly, every effort should be made to reduce exposure to transfusions and this was more successful in the Effects of Transfusion Thresholds on Neurocognitive Outcomes (ETTNO) study. In this review, we look at factors which may explain these transfusion differences and the differences in outcomes, in particular neurodevelopment at age 2 years. In choosing which guidelines to follow, centers using liberal guidelines should be encouraged to adopt more restrictive ones. However, should centers with more restrictive guidelines change to ones similar to those in the studies? The evidence for this is less compelling, particularly given the wide range of transfusion exposure between studies. Individual centers already using restrictive guidelines should assess the validity of the findings in light of their own transfusion experience. In addition, it should be remembered that the study guidelines were pragmatic and acceptable to a large number of centers. The major focus in these guidelines was on hemoglobin levels which do not necessarily reflect tissue oxygenation. Other factors such as the level of erythropoiesis should also be taken into account before deciding whether to transfuse.

Iatrogenic Blood Loss in Very Low Birth Weight Infants and Transfusion of Packed Red Blood Cells in a Tertiary Care Neonatal Intensive Care Unit

An adequate blood volume is important for neonatal adaptation. The study objective was to quantify the cumulative iatrogenic blood loss in very low birth weight (VLBW) infants by blood sampling and the necessity of packed red cell transfusions from birth to discharge from the hospital. In total, 132 consecutive VLBW infants were treated in 2019 and 2020 with a median birth weight of 1180 g (range 370–1495 g) and a median length of stay of 54 days (range 0–154 days) were included. During the initial four weeks of life, the median absolute amount of blood sampling was 16.5 mL (IQR 12.3–21.1 mL), sampling volume was different with 14.0 mL (IQR 12.1–16.2 mL) for non-transfused infants and 21.6 mL (IQR 17.5–29.4 mL) for transfused infants. During the entire length of stay, 31.8% of the patients had at least one transfusion. In a generalized logistic regression model, the cumulative amount of blood sampling (p < 0.01) and lower hematocrit at birth (p = 0.02) were independent predictors for the necessity of blood transfusion. Therefore, optimized patient blood management in VLBW neonates should include sparse blood sampling to avoid iatrogenic blood loss.

Iron Nutrition, Erythrocytes, and Erythropoietin in the NICU: Erythropoietic and Neuroprotective Effects

Prematurity, maternal diabetes, maternal smoking, being medically underserved, and small size for gestational age are common characteristics of neonates in the NICU and can predispose them to develop congenital iron deficiency. Iron is critical for organ development. In the fetus and newborn, iron is prioritized for red blood cell production, sometimes at the expense of other tissues, including the brain. It is critical to optimize iron levels in newborns to support erythropoiesis, growth, and brain development. Available studies support improved neurodevelopmental outcomes with either iron supplementation or delayed umbilical cord clamping at birth. Erythropoietic doses of erythropoietin/erythrocyte-stimulating agents may also improve neurocognitive outcomes. However, the literature on the effect of liberal red blood cell transfusions on long-term neurodevelopment is mixed. Understanding age-specific normal values and monitoring of iron indices can help individualize and optimize the iron status of patients in the NICU.

Are single-donor red blood cell transfusions still relevant for preterm infants?

OBJECTIVE

To explore the worth of a single-donor program for preterm infants through the recipient profile and the impact on donor exposure, red blood cell (RBC) pack waste, storage duration, and transfusion performance.

STUDY DESIGN

Patients and transfusion characteristics were collected for 3 years (2015-2017) in preterm infants according to single-donor program prescription in a unit not practicing placental transfusion or erythropoietin supplementation.

RESULTS

Among 1048 eligible preterm infants, 161 met the inclusion criteria, and 51 received single-donor packs. Our single-donor program induced a donor number reduction (34% less than the transfusion number) and an extension of storage duration (median: 9 versus 7 days, p < 0.0001) without altering the transfusion performance. However, 41% of small packs were not used.

CONCLUSION

A single-donor program partially reduced donor exposure but led to drastic RBC pack waste. Optimization of transfusion alternatives may increase this phenomenon, calling into question the rationale of this practice.

Long-term outcome of brain structure in female preterm infants: possible associations of liberal versus restrictive red blood cell transfusions

BACKGROUND

Preterm infants who receive differential red blood cell (RBC) transfusions at birth may show brain structure differences across development, including abnormalities in white matter (WM) structure and organization. This study investigated long-term outcomes of brain structure in female infants born preterm, at an average age of 13 years old, who received red blood cell (RBC) transfusions in the neonatal period according to a liberal or restrictive approach. Results from this study will increase understanding of the effects of transfusion on the developing brain.

STUDY DESIGN AND METHODS

This follow-up study included female preterm infants who participated in a clinical trial and had been randomized at birth to either a liberal or restrictive hematocrit threshold. Brain structures were measured in childhood using structural magnetic resonance imaging (MRI) scans. Due to the low number of females in the restrictive transfusion group at follow-up, additional females were recruited for inclusion. Main outcome measures included cerebral and subcortical brain region volumes.

RESULTS

Total intracranial volume was significantly decreased in females who were randomized to higher average hematocrit levels at birth. Infants in the liberal transfusion group had proportionately smaller volumes in all measures of regional cerebral WM and subcortical brain volumes, reaching significance for temporal lobe WM and caudate volumes.

CONCLUSION

Female premature infants who received a liberal transfusion threshold at birth had decreased WM volumes, which suggests the potential long-term neurodevelopmental risks associated with liberal transfusion practices.

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.

The role of recombinant Human erythropoietin in neonatal anemia

AIM

To estimate the blood level of Erythropoietin(EPO) in neonates with anemia of prematurity (APO) and in late hypo-regenerative anemia and to clarify role of EPO in correction of anemia and reducing the number of blood transfusions.

METHODS

This study was carried out on 60 neonates divided into; group I (30 preterm neonates) with AOP received EPO (250 IU/kg/dose subcutaneously 3 times weekly for 4 weeks), compared to group II (30 neonates) with AOP treated only with blood transfusion. CBC parameters and transfusion requirements were followed during therapy. Serum level of EPO was measured by ELISA technique.

RESULTS

By the end of the 4th week of therapy, there was significant increase in group I post r-Hu EPO compared to group II regarding reticulocyte counts (P < 0.001) leading to rise of the Hb (P < 0.001), Hct levels (P < 0.001) with subsequent reduction in the overall number of blood transfusions (P < 0.001).

CONCLUSION

EPO therapy in conjunction with iron, vitamin E and folic acid, stimulated erythropoiesis and significantly reduced the need for blood transfusion in AOP.

Optimizing Measurement of Vascular Endothelial Growth Factor in Small Blood Samples of Premature Infants

To establish a method that allows for the reliable assessment of vascular endothelial growth factor (VEGF-A) concentrations in very small blood samples of preterm infants. Systemic VEGF measurements are important in view of the most appropriate Anti-VEGF drug to be used for the treatment of acute retinopathy of prematurity (ROP). Cord blood samples from preterm (n = 6) infants, blood samples from preterm infants with treatment requiring ROP (n = 12), and blood samples from healthy adults (n = 10) were collected. Serum, citrate plasma, and serum from recalcified citrate blood were obtained. Levels of VEGF-A and platelet factor-4 (PF-4) were quantified by ELISA or AlphaLISA immunoassay. VEGF-A levels could be detected by both assays, with the AlphaLISA generating slightly lower levels in healthy adults, but not in cord blood of preterm infants. In plasma samples, VEGF levels ranged from non detectable to 181 pg/ml. PF-4 concentrations were between 0.16–3.88 µg/ml. Values of VEGF-A and PF-4 in serum and recalcified serum were significantly higher compared to plasma through the release of these cytokines after platelet activation. In plasma samples of infants with ROP, VEGF-A could always be detected and its values ranged from 19.50 to 245.91 pg/ml and PF-4 concentrations were between 0.1 and 3.3 µg/ml. Using the AlphaLISA kit, we were able to detect VEGF in small sample volumes (5 µl plasma or serum/well) in premature infants with treatment requiring ROP and to monitor platelet activation by PF-4 detection. Minimal blood probe volumes reduce phlebotomy losses avoiding the risk of iatrogenic anemia, thus allowing close monitoring of the cytokine levels in these very fragile infants.

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.

Elevated brain oxygen extraction fraction in preterm newborns with anemia measured using noninvasive MRI

OBJECTIVE

To test the hypothesis that cerebral oxygen extraction fraction (OEF) is elevated and inversely related to hematocrit level in anemic former very-low-birth-weight infants near term.

STUDY DESIGN

Prospective study of non-sedated preterm infants (post-menstrual age = 36 ± 2 weeks) over a range of hematocrits (0.23-0.49). Anatomical (T₁-W, T₂-W, and diffusion-weighted), cerebral blood flow (CBF), and OEF 3-T MRI were utilized. Statistical analysis included Spearman's rank-order correlation testing between study variables and intraclass correlation coefficients (ICC) calculated between consecutively acquired OEF scans.

RESULTS

Consecutive OEF measurements showed moderate-to-good agreement (ICC = 0.71; 95% CI = 0.40-0.87). OEF increased with worsening anemia (ρ = -0.58; p = 0.005), and OEF and basal ganglia CBF were positively correlated (ρ = 0.49; p = 0.023).

CONCLUSION

Noninvasive OEF MRI has moderate-to-good repeatability in non-sedated former preterm infants nearing term-equivalent age. Strong correlation of elevated OEF with anemia suggests hemodynamic compensation for anemia and could establish OEF as a useful biomarker of transfusion threshold for preterm infants.

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.