Two-year outcomes following a randomised platelet transfusion trial in preterm infants

Blood product transfusion practices in neonates with hypoxic-ischemic encephalopathy

OBJECTIVE

Blood product transfusion is a common practice in infants with hypoxic-ischemic encephalopathy (HIE) undoing therapeutic hypothermia (TH). The advantages and disadvantages of conservative or liberal transfusion practices in this fragile population are unknown. Study aims to characterize the transfusion practices in infants with HIE and investigate the association with outcome.

STUDY DESIGN

We conducted a retrospective cohort study at a single level IV NICU, evaluating transfusion thresholds, as well as the association between hematological abnormalities or blood product transfusions and outcomes in infants admitted with HIE.

RESULT

By univariate analysis, FFP transfusion was associated with increased in-hospital death. However, multivariate analysis adjusting for HIE severity demonstrated no association between hematological abnormality or blood product transfusion and death, nor with neurodevelopmental impairment.

CONCLUSION

No association was found between hematological blood product transfusion and death or neurodevelopmental impairment in a retrospective single NICU study of infants with HIE.

Implementing evidence-based restrictive neonatal intensive care unit platelet transfusion guidelines

Platelet transfusions are life-saving treatments for specific populations of neonates. However, recent evidence indicates that liberal prophylactic platelet transfusion practices cause harm to premature neonates. New efforts to better balance benefits and risks are leading to the adoption of more restrictive platelet transfusion guidelines in neonatal intensive care units (NICU). Although restrictive guidelines have the potential to improve outcomes, implementation barriers exist. We postulate that as neonatologists become more familiar with the data on the harm of liberal platelet transfusions, enthusiasm for restrictive guidelines will increase and barriers to implementation will decrease. Thus, we focused this educational review on; (1) the adverse effects of platelet transfusions to neonates, (2) awareness of platelet transfusion "refractoriness" in thrombocytopenic neonates and its association with poor outcomes, and (3) the impetus to find alternatives to transfusing platelets from adult donors to NICU patients.

Judicious Transfusion of Platelets Among Neonates: A Systematic Review

In newborns, especially premature babies, there is a high association between thrombocytopenia and bleeding, particularly intraventricular hemorrhage, which may be due to immaturity. It was usual clinical practice that neonates should be transfused with higher platelet counts than older children or adults to reduce their risk of bleeding. However, after keen observations, we noticed that bleeding and mortality were more common in newborns who received more platelet transfusions. The mechanisms underlying the adverse effects of platelet transfusions in neonates may be due to higher antigenicity and immunological factors. We know that neonatal platelets are hyporeactive; this hyporeactivity is balanced by factors in the neonatal blood that promote coagulation, such as increased hematocrit, von Willebrand factor, and fibrinogen, which, on balance, leads to normal primary neonatal hemostasis. Platelets are very similar to adults in number, but functional capabilities were less, and for the reasons mentioned above, particularly bleeding time was short. Theologically, neonatal platelet lifespan was high to compensate for less production. We started this review because we observed that many babies were not having bleeding symptoms in some instances of severe thrombocytopenia. Many well-active babies are receiving unnecessary transfusions, as human blood is precious, and many young neonatologists are going on protocol-based excessive transfusions. This stimulated us to write a review.

Platelet Transfusion and Death or Neurodevelopmental Impairment in Children Born Extremely Preterm

Importance

Infants born extremely preterm receive transfusions at higher platelet count thresholds than older children and adults due to concerns for intracranial hemorrhage. A recent randomized trial comparing 2 platelet transfusion thresholds showed the higher threshold was associated with increased risk of long-term adverse neurodevelopmental outcomes.

Objective

To evaluate the association of platelet transfusion exposure with death and severe neurodevelopmental impairment (NDI) at 2 years' corrected age in a cohort of infants born extremely preterm.

Design, Setting, and Participants

An observational cohort study and secondary analysis of the Preterm Erythropoietin Neuroprotection Trial, a randomized, placebo-controlled clinical trial of erythropoietin neuroprotection in neonates born extremely preterm, was conducted in 30 neonatal intensive care units in the US from December 1, 2013, to September 31, 2016. This analysis included 819 infants born extremely preterm at 24 to 27 completed weeks of gestation who had a documented outcome (death or neurodevelopmental assessment). Analysis was performed in April 2023.

Exposures

Any platelet transfusion during neonatal intensive care unit hospitalization.

Main Outcomes and Measures

The primary composite outcome was death or severe NDI evaluated at 2 years' corrected age using the Bayley Scales of Infant Development-Third Edition (BSID-III) and the Gross Motor Function Classification System and was defined as the presence of severe cerebral palsy or a BSID-III composite motor or cognitive score 2 SDs below the mean. Confounding by indication for platelet transfusion was addressed with covariate adjustment and propensity score methods.

Results

Of the 819 infants included in the analysis (429 [52.4%] male; mean [SD] gestational age, 25.5 [1.1] weeks), 245 (30.0%) received at least 1 platelet transfusion during their initial hospitalization. The primary outcome occurred in 46.5% (114 of 245) of infants exposed to a platelet transfusion and 13.9% (80 of 574) of nonexposed infants with a corresponding odds ratio of 2.43 (95% CI, 1.24-4.76), adjusted for propensity score, gestational age at birth, and trial treatment group. The individual components of death and severe NDI were directionally consistent with the overall composite outcome.

Conclusions and Relevance

The findings of this study suggest that platelet transfusion in infants born extremely preterm may be associated with an increased risk of death or severe NDI at 2 years' corrected age, although the possibility of residual confounding by indication cannot be excluded.

Neonatal Thrombocytopenia: Factors Associated With the Platelet Count Increment Following Platelet Transfusion

OBJECTIVE

To understand better those factors relevant to the increment of rise in platelet count following a platelet transfusion among thrombocytopenic neonates.

STUDY DESIGN

We reviewed all platelet transfusions over 6 years in our multi-neonatal intensive care unit system. For every platelet transfusion in 8 neonatal centers we recorded: (1) platelet count before and after transfusion; (2) time between completing the transfusion and follow-up count; (3) transfusion volume (mL/kg); (4) platelet storage time; (5) sex and age of platelet donor; (6) gestational age at birth and postnatal age at transfusion; and magnitude of rise as related to (7) pre-transfusion platelet count, (8) method of enhancing transfusion safety (irradiation vs pathogen reduction), (9) cause of thrombocytopenia, and (10) donor/recipient ABO group.

RESULTS

We evaluated 1797 platelet transfusions administered to 605 neonates (median one/recipient, mean 3, and range 1-52). The increment was not associated with gestational age at birth, postnatal age at transfusion, or donor sex or age. The rise was marginally lower: (1) with consumptive vs hypoproductive thrombocytopenia (P < .001); (2) after pathogen reduction (P < .01); (3) after transfusing platelets with a longer storage time (P < .001); and (4) among group O neonates receiving platelets from non-group O donors (P < .001). Eighty-seven neonates had severe thrombocytopenia (<20 000/μL). Among these infants, poor increments and death were associated with the cause of the thrombocytopenia.

CONCLUSION

The magnitude of post-transfusion rise was unaffected by most variables we studied. However, the increment was lower in neonates with consumptive thrombocytopenia, after pathogen reduction, with longer platelet storage times, and when not ABO matched.

Hemostatic and Immunologic Effects of Platelet Transfusions in Neonates

Liberal platelet transfusions are associated with increased morbidity and mortality among preterm neonates, and it is now recognized that platelets are both hemostatic and immune cells. Neonatal and adult platelets are functionally distinct, and adult platelets have the potential to be more immuno-active. Preclinical studies suggest that platelet transfusions (from adult donors) can trigger dysregulated immune responses in neonates, which might mediate the increased morbidity and mortality observed in clinical studies. More research is needed to understand how neonatal and adult platelets differ in their immune functions and the consequences of these differences in the setting of neonatal platelet transfusions.

Patient Blood Management in Neonates

Patient blood management (PBM) is an evidence-based care package to improve patient outcomes by optimizing a patient's blood, minimizing blood loss, and the effective management and, when appropriate, the tolerance of anemia. It is relatively well-developed in adult medicine and remains in its infancy in neonatology. This review explores why evidence-based guidelines are insufficient, discusses the variations in neonatal transfusion practice and why this matters, and provides the key updates in neonatal transfusion practice. The authors give examples of a successful neonatal PBM program and single-center projects.

Prophylactic Platelet Transfusions: Why Less Is More

Preterm neonates are a highly transfused patient group, with platelet transfusions being the second most transfused cellular blood component. Historically, however, evidence to inform optimal platelet transfusion practice has been limited. In pediatrics, much of the evidence has been inferred from studies in adult patients, although neonatologists have generally applied more cautious and liberal platelet transfusion thresholds to mitigate the complications of intraventricular hemorrhage. A total of three randomized controlled trials have now been published comparing different platelet transfusion strategies in neonates.

Phosphoproteomics reveals content and signaling differences between neonatal and adult platelets

Background and Objective

Recent clinical studies have shown that transfusions of adult platelets increase morbidity and mortality in preterm infants. Neonatal platelets are hyporesponsive to agonist stimulation, and emerging evidence suggests developmental differences in platelet immune functions. This study was designed to compare the proteome and phosphoproteome of resting adult and neonatal platelets.

Methods

We isolated resting umbilical cord blood-derived platelets from healthy full term neonates (n=9) and resting blood platelets from healthy adults (n=7), and compared protein and phosphoprotein contents using data independent acquisition mass spectrometry.

Results

We identified 4745 platelet proteins with high confidence across all samples. Adult and neonatal platelets clustered separately by principal component analysis. Adult platelets were significantly enriched for immunomodulatory proteins, including β2 microglobulin and CXCL12, whereas neonatal platelets were enriched for ribosomal components and proteins involved in metabolic activities. Adult platelets were enriched for phosphorylated GTPase regulatory enzymes and proteins participating in trafficking, which may help prime them for activation and degranulation. Neonatal platelets were enriched for phosphorylated proteins involved in insulin growth factor signaling.

Conclusions

Using state-of-the-art mass spectrometry, our findings expanded the known neonatal platelet proteome and identified important differences in protein content and phosphorylation compared with adult platelets. These developmental differences suggested enhanced immune functions for adult platelets and presence of a molecular machinery related to platelet activation. These findings are important to understanding mechanisms underlying key platelet functions as well as the harmful effects of adult platelet transfusions given to preterm infants.