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Limited data suggest that higher hemoglobin thresholds for red-cell transfusions may reduce the risk of cognitive delay among extremely-low-birth-weight infants with anemia.We performed an open, multicenter trial in which infants with a birth weight of 1000 g or less and a gestational age between 22 weeks 0 days and 28 weeks 6 days were randomly assigned within 48 hours after delivery to receive red-cell transfusions at higher or lower hemoglobin thresholds until 36 weeks of postmenstrual age or discharge, whichever occurred first. The primary outcome was a composite of death or neurodevelopmental impairment (cognitive delay, cerebral palsy, or hearing or vision loss) at 22 to 26 months of age, corrected for prematurity.A total of 1824 infants (mean birth weight, 756 g; mean gestational age, 25.9 weeks) underwent randomization. There was a between-group difference of 1.9 g per deciliter (19 g per liter) in the pretransfusion mean hemoglobin levels throughout the treatment period. Primary outcome data were available for 1692 infants (92.8%). Of 845 infants in the higher-threshold group, 423 (50.1%) died or survived with neurodevelopmental impairment, as compared with 422 of 847 infants (49.8%) in the lower-threshold group (relative risk adjusted for birth-weight stratum and center, 1.00; 95% confidence interval [CI], 0.92 to 1.10; P = 0.93). At 2 years, the higher- and lower-threshold groups had similar incidences of death (16.2% and 15.0%, respectively) and neurodevelopmental impairment (39.6% and 40.3%, respectively). At discharge from the hospital, the incidences of survival without severe complications were 28.5% and 30.9%, respectively. Serious adverse events occurred in 22.7% and 21.7%, respectively.In extremely-low-birth-weight infants, a higher hemoglobin threshold for red-cell transfusion did not improve survival without neurodevelopmental impairment at 22 to 26 months of age, corrected for prematurity. (Funded by the National Heart, Lung, and Blood Institute and others; TOP ClinicalTrials.gov number, NCT01702805.).

Our aim was to build a mechanistic full target-mediated drug disposition (TMDD) model for rhEpo to better understand rhEpo disposition, Epo receptor (EpoR) synthesis, and degradation in hematopoietic transplant patients with four distinct bone marrow conditions. All PK data were analyzed simultaneously using the nonlinear mixed effect modeling approach with NONMEM. The final model was a two-compartmental full TMDD model, which adequately characterizes rhEpo PK in patients and provides insight into the dynamics of free EpoR, rhEpo-EpoR, and total EpoR. The model predicted association rate constant (k

BACKGROUND: In hematologic and transfusion medicine research, measurement of red blood cell (RBC) in vivo kinetics must be safe and accurate. Recent reports indicate use of biotin-labeled RBC (BioRBC) to determine red cell survival (RCS) offers substantial advantages over (51)Cr and other labeling methods. Occasional induction of BioRBC antibodies has been reported. STUDY DESIGN AND METHODS: To investigate the causes and consequences of BioRBC immunization, we reexposed three previously immunized adults to BioRBC and evaluated the safety, antibody emergence, and RCS of BioRBC. RESULTS: BioRBC re-exposure caused an anamnestic increase of plasma BioRBC antibodies at 5–7 days; all were subclass IgG(1) and neutralized by biotinylated albumin, thus indicating structural specificity for the biotin epitope. Concurrently, specific antibody binding to BioRBC was observed in each subject. As biotin label density increased, the proportion of BioRBC that bound increased antibody also increased; the latter was associated with proportional accelerated removal of BioRBC labeled at density 6 μg/mL. In contrast, only one of three subjects exhibited accelerated removal of BioRBC density 2 μg/mL. No adverse clinical or laboratory events were observed. Among three control subjects who did not develop BioRBC antibodies following initial BioRBC exposure, re-exposure induced neither antibody emergence nor accelerated BioRBC removal. DISCUSSION: We conclude re-exposure of immunized subjects to BioRBC can induce anamnestic antibody response that can cause an underestimation of RCS. To minimize chances of antibody induction and underestimation of RCS, we recommend an initial BioRBC exposure volume of ≤10 mL and label densities of ≤18 μg/mL.

Extremely low birth weight (ELBW) infants are at risk for end-organ hypoxia and ischemia. Regional tissue oxygenation of the brain and gut as monitored with near-infrared spectroscopy (NIRS) may change with postnatal age, but normal ranges are not well defined.A prospective study of ELBW preterm infants utilized NIRS monitoring to assess changes in cerebral and mesenteric saturation (Csat and Msat) over the first week after birth. This secondary study of a multicenter trial comparing hemoglobin transfusion thresholds assessed cerebral and mesenteric fractional tissue oxygen extraction (cFTOE and mFTOE) and relationships with perinatal variables.In 124 infants, both Csat and Msat declined over the first week, with a corresponding increase in oxygen extraction. With lower gestational age, lower birth weight, and 5-min Apgar score ≤5, there was a greater increase in oxygen extraction in the brain compared to the gut. Infants managed with a lower hemoglobin transfusion threshold receiving ≥2 transfusions in the first week had the lowest Csat and highest cFTOE (p 0.001).Brain oxygen extraction preferentially increased in more immature and anemic preterm infants. NIRS monitoring may enhance understanding of cerebral and mesenteric oxygenation patterns and inform future protective strategies in the preterm ELBW population.Simultaneous monitoring of cerebral and mesenteric tissue saturation demonstrates the balance of oxygenation between preterm brain and gut and may inform protective strategies. Over the first week, oxygen saturation of the brain and gut declines as oxygen extraction increases. A low hemoglobin transfusion threshold is associated with lower cerebral saturation and higher cerebral oxygen extraction compared to a high hemoglobin transfusion threshold, although this did not translate into clinically relevant differences in the TOP trial primary outcome. Greater oxygen extraction by the brain compared to the gut occurs with lower gestational age, lower birth weight, and 5-min Apgar score ≤5.

The objective of the current study was to develop a population pharmacokinetics (PK) model for erythropoietin (Epo) in premature infants and healthy adults to characterize the variation in PK, and to study the differences in Epo PK in these 2 populations. Thirteen very low-birth-weight premature infants (

The current reference method in the United States for measuring in vivo population red blood cell (RBC) kinetics utilizes chromium-51 (51 Cr) RBC labeling for determining RBC volume, 24-hour posttransfusion RBC recovery, and long-term RBC survival. Here we provide evidence supporting adoption of a method for kinetics that uses the biotin-labeled RBCs (BioRBCs) as a superior, versatile method for both regulatory and investigational purposes. RBC kinetic analysis using BioRBCs has important methodologic, analytical, and safety advantages over 51 Cr-labeled RBCs. We critically review recent advances in labeling human RBCs at multiple and progressively lower biotin label densities for concurrent, accurate, and sensitive determination of both autologous and allogeneic RBC population kinetics. BioRBC methods valid for RBC kinetic studies, including successful variations used by the authors, are presented along with pharmacokinetic modeling approaches for the accurate determination of RBC pharmacokinetic variables in health and disease. The advantages and limitations of the BioRBC method-including its capability of determining multiple BioRBC densities simultaneously in the same individual throughout the entire RBC life span-are presented and compared with the 51 Cr method. Finally, potential applications and limitations of kinetic BioRBC determinations are discussed.

OBJECTIVE: To evaluate the effects of early treatment with CPAP on nutritional intake and in-hospital growth rates of extremely preterm (EPT) infants. STUDY DESIGN: EPT infants (24–0/7 to 27–6/7 weeks of gestation) enrolled in the Surfactant Positive Airway Pressure and Pulse Oximetry Trial (SUPPORT) were included. EPT infants who died before 36 weeks’ postmenstrual age (PMA) were excluded. The growth rates from birth to 36 weeks’ PMA and follow-up outcomes at 18–22 months’ corrected age of EPT infants randomized at birth to either early CPAP (intervention group) or early intubation for surfactant administration (control group) were analyzed. RESULTS: 810 of 1316 infants enrolled in SUPPORT (414 in intervention group, 396 in control group) had growth data analyzed. Median gestational age was 26 weeks and mean birthweight was 839 grams. Baseline characteristics, total nutritional intake, and in-hospital comorbidities were not significantly different between groups. In a regression model, growth rates between birth and 36 weeks’ PMA as well as growth rates during multiple intervals from birth to day 7, day 7 to14, day 14 to 21, day 21 to 28, day 28 to 32 weeks’ PMA, and 32 weeks’ PMA to 36 weeks’ PMA did not differ between treatment groups. Independent of treatment group, higher growth rates from day 21 to day 28 were associated with a lower risk of Bayley III cognitive score

BACKGROUND Critically ill preterm very-low-birthweight (VLBW) neonates (birthweight ≤ 1.5 kg) frequently develop anemia that is treated with red blood cell (RBC) transfusions. Although RBCs transfused to adults demonstrate progressive decreases in posttransfusion 24-hour RBC recovery (PTR24 ) during storage-to a mean of approximately 85% of the Food and Drug Administration-allowed 42-day storage-limited data in infants indicate no decrease in PTR24 with storage. STUDY DESIGN AND METHODS We hypothesized that PTR24 of allogeneic RBCs transfused to anemic VLBW newborns: 1) will be greater than PTR24 of autologous RBCs transfused into healthy adults and 2) will not decrease with increasing storage duration. RBCs were stored at 4°C for not more than 42 days in AS-3 or AS-5. PTR24 was determined in 46 VLBW neonates using biotin-labeled RBCs and in 76 healthy adults using 51 Cr-labeled RBCs. Linear mixed-model analysis was used to estimate slopes and intercepts of PTR24 versus duration of RBC storage. RESULTS For VLBW newborns, the estimated slope of PTR24 versus storage did not decrease with the duration of storage (p = 0.18) while for adults it did (p

Darbepoetin alfa (Darbe) is a hyperglycosylated analogue of recombinant human erythropoietin (Epo). The aim of this study was to develop a population pharmacokinetic model for Darbe following intravenous (i.v.) and subcutaneous (s.c.) administration to infants. Data from 2 infant clinical studies (a single i.v. dose study following a 4 μg/kg dose of Darbe, and a single s.c. dose study following 1 μg/kg or 4 mg/kg dose of Darbe) were combined and analyzed simultaneously using nonlinear mixed-effect modeling approach. Darbe population pharmacokinetics was well described by a 2-compartment model with first-order elimination. The covariate analysis identified significant impact of gender on clearance and bodyweight on volume of distribution. The clearance of Darbe was estimated to be 0.050 L/h/kg in male infants and 0.031 L/h/kg in female infants. The predicted population mean value of Vp is 0.84 L/kg, which is associated with the subject’s bodyweight (p < 0.05). Following s.c. administration, the estimated absorption rate (i.e., ka) of Darbe was 0.062 L/h. The model provides a suitable starting point for the development of further pharmacokinetic-pharmacodynamic models in infants in a variety of disease settings. Because the covariate-pharmacokinetic parameter relationships were identified in only 22 infants, further investigation with larger sample size is warranted.

Background Biotin-labeled red blood cells (BioRBCs) are used for in vivo kinetic studies. Because BioRBC dosing occasionally induces antibodies, a sensitive and specific anti-BioRBC detection assay is needed. Study design and methods Aims were to 1) develop a gel card assay to evaluate existing, naturally occurring and BioRBC-induced plasma antibodies, 2) compare gel card and tube agglutination detection results, and 3) test for a relationship of antibody induction and BioRBC dose. Reagent BioRBCs were prepared using sulfo-NHS biotin ranging from densities 18 (BioRBC-18) to 1458 (BioRBC-1458) µg/mL RBCs. Results Among BioRBC-exposed subjects, gel card and tube agglutination results were concordant in 21 of 22 adults and all 19 infant plasma samples. Gel card antibody detection sensitivity was more than 10-fold greater than tube agglutination. Twelve to 16 weeks after BioRBC exposure, induced anti-antibodies were detected by gel card in three of 26 adults (12%) at reagent densities BioRBC-256 or less, but in none of 41 infants. Importantly, induced anti-BioRBC antibodies were associated with higher BioRBC dose (p = 0.008); no antibodies were detected in 18 subjects who received BioRBC doses less than or equal to BioRBC-18. For noninduced BioRBC antibodies, six of 1125 naive adults (0.3%) and none of 46 naive infants demonstrated existing anti-BioRBC antibodies using reagent BioRBC-140 or -162. Existing anti-BioRBCs were all neutralized by biotin compounds, while induced antibodies were not. Conclusions The gel card assay is more sensitive than the tube agglutination assay. We recommend reagent BioRBC-256 for identifying anti-BioRBCs. Use of a low total RBC biotin label dose (≤ BioRBC-18) may minimize antibody induction.

OBJECTIVE: To evaluate neurodevelopmental outcomes of preterm infants with need for Child Protective Services (CPS) supervision at hospital discharge compared with those discharged without CPS supervision. STUDY DESIGN: For infants born at

Routine erythropoietin (Epo) therapy for neonatal anemia is presently controversial due to its modest response. We speculate that an important contributor to this modest response is that previous clinical study designs were not driven by rigorous mechanistic and kinetic insights into the complex pharmacokinetics (PK) and pharmacodynamics (PD) of Epo in this population. To address this therapeutic opportunity, we conducted a prospective clinical study to investigate the PK of Epo in very-low-birth-weight (VLBW) premature neonates using a unique Epo dosing algorithm that accounts for complex neonatal erythropoietic physiology. Twenty-seven subjects received up to 10 intravenous or subcutaneous exogenous doses of Epo (600 or 1,200 U/kg) during the first 4 weeks of life. Subjects were administered two doses of Epo 1,200 U/kg on days 2 and 16, and eight doses of Epo 600 U/kg on days 4, 5, 6, 7, 9, 14, 15, and 28 following birth. We have developed for the first time a mechanistic, target-mediated disposition model that provides novel insights into the mechanisms driving Epo PK in VLBW neonates. Epo association rate, k(on), was estimated to be 0.00610 pM(−1)h(−1), and the dissociation rate k(off) was 0.112 h(−1). Internalization of the Epo-target complex (k(int)) and the total receptor concentration (R(max)) were estimated to be 0.118 h(−1) and 133 pM, respectively. Following s.c. administration, the absorption rate (k(a)) of Epo was 0.0738 h(−1) and bioavailability was 78.0 %. Our mechanism-based population pharmacokinetic analysis provided quantitative insight into Epo kinetics in VLBW neonates; the information gained will assist in deriving dosing strategies for neonatal anemia and for neuroprotection efficacy studies.

Background While very low birth weight (VLBW) infants often require multiple red blood cell transfusions, efforts to minimize transfusion-associated risks have resulted in more restrictive neonatal transfusion practices. However, whether restrictive transfusion strategies limit transfusions without increasing morbidity and mortality in this population remains unclear. Recent epidemiologic studies suggest that severe anemia may be an important risk factor for the development of necrotizing enterocolitis (NEC). However, the mechanism whereby anemia may lead to NEC remains unknown. Study design and methods The potential impact of anemia on neonatal inflammation and intestinal barrier disruption, two well-characterized predisposing features of NEC, was defined by correlation of hemoglobin values to cytokine levels in premature infants and by direct evaluation of intestinal hypoxia, inflammation and gut barrier disruption using a pre-clinical neonatal murine model of phlebotomy-induced anemia (PIA). Results Increasing severity of anemia in the preterm infant correlated with the level of IFN-gamma, a key pro-inflammatory cytokine that may predispose an infant to NEC. Gradual induction of PIA in a pre-clinical model resulted in significant hypoxia throughout the intestinal mucosa, including areas where intestinal macrophages reside. PIA-induced hypoxia significantly increased macrophage pro-inflammatory cytokine levels, while reducing tight junction protein ZO-1 expression and increasing intestinal barrier permeability. Macrophage depletion reversed the impact of anemia on intestinal ZO-1 expression and barrier function. Conclusions Taken together, these results suggest that anemia can increase intestinal inflammation and barrier disruption likely through altered macrophage function, leading to the type of predisposing intestinal injury that may increase the risk for NEC.

Red blood cell (RBC) transfusion is a common and lifesaving therapy for anemic neonates and infants, particularly among those born prematurely or undergoing surgery. However, evidence-based indications for when to administer RBCs and adverse effects of RBC transfusion on important outcomes including necrotizing enterocolitis, survival, and long-term neurodevelopmental impairment remain uncertain. In addition, blood-banking practices for preterm and term neonates and infants have been largely developed using studies from older children and adults. Use of and refinements in emerging technologies and advances in biomarker discovery and neonatal-specific RBC transfusion databases may allow clinicians to better define and tailor RBC transfusion needs and practices to individual neonates. Decreasing the need for RBC transfusion and developing neonatal-specific approaches in the preparation of donor RBCs have potential for reducing resource utilization and cost, improving outcomes, and assuring blood safety. Finally, large donor-recipient-linked cohort studies can provide data to better understand the balance of the risks and benefits of RBC transfusion in neonates. These studies may also guide the translation of new research into best practices that can rapidly be integrated into routine care. This review highlights key opportunities in transfusion medicine and neonatology for improving the preparation and transfusion of RBCs into neonates and infants. We focus on timely, currently addressable knowledge gaps that can increase the safety and efficacy of preterm and term neonatal and infant RBC transfusion practices.

Direct measurement of red blood cell (RBC) survival in humans has improved from the original accurate but limited differential agglutination technique to the current reliable, safe, and accurate biotin method. Despite this, all of these methods are time consuming and require blood sampling over several months to determine the RBC lifespan. For situations in which RBC survival information must be obtained quickly, these methods are not suitable. With the exception of adults and infants, RBC survival has not been extensively investigated in other age groups. To address this need, we developed a novel, physiology-based mathematical model that quickly estimates RBC lifespan in healthy individuals at any age. The model is based on the assumption that the total number of RBC recirculations during the lifespan of each RBC (denoted by N max) is relatively constant for all age groups. The model was initially validated using the data from our prior infant and adult biotin-labeled red blood cell studies and then extended to the other age groups. The model generated the following estimated RBC lifespans in 2-year-old, 5-year-old, 8-year-old, and 10-year-old children: 62, 74, 82, and 86 days, respectively. We speculate that this model has useful clinical applications. For example, HbA1c testing is not reliable in identifying children with diabetes because HbA1c is directly affected by RBC lifespan. Because our model can estimate RBC lifespan in children at any age, corrections to HbA1c values based on the model-generated RBC lifespan could improve diabetes diagnosis as well as therapy in children.

BACKGROUND It is thought that the clearance of transfused red blood cells (RBCs) is related both to the storage time of the transfusion product and to the inflammatory status of the recipient. We investigated these effects in a randomized, “two-hit,” healthy volunteer transfusion model, comparing autologous RBCs that were stored for 35 days with those that were stored for 2 days. STUDY DESIGN AND METHODS Healthy male volunteers donated 1 unit of autologous RBCs either 2 days (2D) or 35 days (35D) before the study date. The experiment was started by infusion of 2 ng/kg lipopolysaccharide (“first hit”). Two hours later, the stored RBCs (“second hit”) were reinfused, followed by the labeling of RBCs with biotin. Clearance of biotin-labeled RBCs (BioRBCs) was measured during the 5-hour posttransfusion endotoxemia period along with measurements of phosphatidylserine (PS) exposure, lactadherin binding, and expression of CD47 (cluster of differentiation 47; a transmembrane protein encoded by the CD47 gene). RESULTS In the 2D stored RBCs group, 1.5% ± 3.4% of infused BioRBCs were cleared from the circulation 5 hours posttransfusion versus 4.8% ± 4.0% in the 35D stored RBCs group (p = 0.1). There were no differences in PS exposure, lactadherin binding, or CD47 expression between fresh and stored RBCs or between pretransfusion and posttransfusion measurements. CONCLUSION Our study shows a low clearance of RBCs even during endotoxemia. Furthermore, short-term clearance of BioRBCs during endotoxemia was not related to storage duration. Consistent with these observations, PS exposure, lactadherin binding, and CD47 expression did not differ between 2D and 35D stored cells before or after transfusion. We conclude that, in the presence of endotoxemia, clearance of 35D stored autologous RBCs is not increased compared with 2D stored fresh RBCs.

The objective of this review is to provide an integrated historical account of the complex, often convoluted events impacting milk hygiene and its resultant effect on infant mortality from 1875 to 1925. Heat pasteurization of cow's milk is necessary for rendering this important nutrient source safe for humans-particularly infants. Developed by Louis Pasteur in 1864, pasteurization evolved from the commercially important parboiling of wine and beer when the Industrial Revolution was effecting rapid societal change in Western societies. In European and American societies of the early and mid-19th century, infant mortality rates were 30- to 60-fold higher than the current rates of five or six deaths per 1,000 live births per year. With proof of the germ theory of disease came convincing evidence of the role of microbes in the transmission of infections, which led to the discovery that microbial pathogens were transmissible via milk. Diseases caused by milkborne pathogens include human and bovine tuberculosis, brucellosis, salmonellosis, streptococcal infections, diphtheria, and "summer diarrhea." With pasteurization of milk, infectious diseases with their high infant mortality rates decreased by only half by the early 20th century, despite concurrent medical and dairy hygiene advances. To further mitigate unacceptably high infant mortality rates, social support providers-including public health nurses and midwives-encouraged breastfeeding, especially among socioeconomically disadvantaged mothers. Improvements in pulsating vacuum milking machines also favorably impacted food safety by providing a clean, enclosed environment. Currently, bottle feeding still competes with breastfeeding as the preferred method, and the sale of raw, unpasteurized milk remains a contentious issue. Informed and responsible food safety professionals, physicians, and public health officials currently view breastfeeding as the preferred feeding method and milk pasteurization as the safer and more prudent alternative.

Objective To investigate associations in toddlers born extremely preterm ( Study design Cohort analysis from the Eunice Kennedy Shriver National Institute of Child Health and Human Development Neonatal Research Network Surfactant Positive Airway Pressure and Pulse Oximetry Trial Neuroimaging and Neurodevelopmental Outcomes Study of infants born extremely preterm. Subjects underwent cranial ultrasonography and near-term magnetic resonance imaging (MRI). At 18-22 months of corrected age, the assessment included the Brief Infant Toddler Social Emotional Assessment (BITSEA) Problem and Competence Scale scores and the Bayley Scales of Infant Development, Third Edition (Bayley-III). The BITSEA Problem Scale assesses dysregulation; the Competence Scale assesses social-emotional competence. We examined associations of Problem and Competence scores and positive screen rates with cranial ultrasonography and near-term MRI. Mean BITSEA and Bayley-III scores were compared using ANOVA and positive screen rates with the χ2 test. We computed correlations between BITSEA and Bayley-III scores. Results Of the 397 children, positive BITSEA screens were found in 34% for the Problem score and 26% for the Competence score. Presence of lesions on near-term MRI that included cerebellar lesions were significantly associated with lower BITSEA Competence but not with Problem scores; Competence scores were inversely related to the presence/significance of lesions. Positive screens on Competence scores and on both Competence and Problem scores were significantly associated with Bayley-III cognitive and language scores Conclusions Social–emotional competence contributes to deficits in cognitive and language development. Presence of injury on near-term MRI that includes cerebellar lesions is associated with later social–emotional competence and may be a useful predictor to guide early assessment and intervention. Trial registration ClinicalTrials.gov : NCT00063063 and NCT00233324 .

Fetal erythropoietin (EPO), in addition to regulating erythropoiesis, has also tissue-protective properties based on its anti-inflammatory, anti-apoptotic, antioxidant, and neurotrophic effects. Notably, EPO concentrations needed for tissue protection are 100-1000 times higher than concentrations needed for regulating erythropoiesis. This dual effect of EPO is based on EPO-receptor (EPO-R) isoforms, which differ structurally and functionally. We hypothesize in this Integrated Mechanism Review that during severe fetal hypoxia the observed, but poorly understood, marked increases of fetal plasma EPO concentrations occur to protect the brain, heart, and other vital fetal organs. We further hypothesize that the concurrent marked increases of EPO in the amniotic fluid during fetal hypoxia, occur to protect newborn infants from necrotizing enterocolitis. This review presents experimental and clinical evidence in support of these hypotheses and points out unknown or poorly understood functions of EPO in the fetus. If these novel hypotheses are correct, the importance of fetal EPO as an antenatal hypoxia biomarker will become apparent. It will also likely point the way to important diagnostic and therapeutic fetal and neonatal interventions.

Neonatal thrombocytopenia affects 22–35% of all neonates admitted to neonatal intensive care units. The purpose of this study was to develop a mathematical model for characterizing platelet (PLT) kinetics in thrombocytopenic preterm neonates. Immature PLT fraction (IPF) and PLT counts were measured for up to 35 days after birth in 27 very low birth weight preterm neonates. PLT transfusions were administered to 8 of the 27 (24%) subjects. The final model included a series of four transit compartments to mimic the production and survival of IPF and PLT. Model parameters were estimated using nonlinear mixed effects modeling with the maximum likelihood expectation maximization algorithm. The model adequately captured the diverse phenotypes expressed by individual subject profiles. Typical population survival values for IPF and PLT life spans in nonthrombocytopenic patients were estimated at 0.912 and 10.7 days, respectively. These values were significantly shorter in thrombocytopenic subjects, 0.429 and 2.56 days, respectively. The model was also used to evaluate the influence of growth and laboratory phlebotomy loss on the time course of IPF and PLT counts. Whereas incorporating body weight was essential to correct for expanding blood volume due to growth, phlebotomy loss, a possible covariate, did not significantly influence PLT kinetics. This study provides a platform for identifying potential covariates that influence the interindividual variability in model parameters regulating IPF and PLT kinetics and for evaluating future pharmacological therapies for treating thrombocytopenic neonates.

Importance Studies of cranial ultrasonography and early childhood outcomes among cohorts of extremely preterm neonates have linked periventricular-intraventricular hemorrhage and cystic periventricular leukomalacia with adverse neurodevelopmental outcomes. However, the association between nonhemorrhagic ventriculomegaly and neurodevelopmental and behavioral outcomes is not fully understood. Objective To characterize the outcomes of extremely preterm neonates younger than 27 weeks’ gestational age who experienced nonhemorrhagic ventriculomegaly that was detected prior to 36 weeks’ postmenstrual age. Design, Setting, and Participants This longitudinal observational study was conducted at 16 centers of the Eunice Kennedy Shriver National Institute of Child Health and Human Development Neonatal Research Network. Infants born prior to 27 weeks’ gestational age in any network facility between July 1, 2006, and June 30, 2011, were included if they had a cranial ultrasonogram performed prior to 36 weeks’ postmenstrual age. Comparisons were made between those with ventriculomegaly and those with normal cranial sonograms. Data analysis was completed from August 2013 to August 2017. Main Outcomes and Measures The main outcome was neurodevelopmental impairment, defined as a Bayley Scales of Infant and Toddler Development III cognitive score less than 70, moderate/severe cerebral palsy, a Gross Motor Function Classification System score of level 2 or more, vision impairment, or hearing impairment. Secondary outcomes included Bayley Scales of Infant and Toddler Development III subscores, components of neurodevelopmental impairment, behavioral outcomes, and death/neurodevelopmental impairment. Logistic regression was used to evaluate the association of ventriculomegaly with adverse outcomes while controlling for potentially confounding variables and center differences as a random effect. Linear regression was used similarly for continuous outcomes. Results Of 4193 neonates with ultrasonography data, 300 had nonhemorrhagic ventriculomegaly (7%); 3045 had normal cranial ultrasonograms (73%), 775 had periventricular-intraventricular hemorrhage (18.5%), and 73 had cystic periventricular leukomalacia (1.7%). Outcomes were available for 3008 of 3345 neonates with ventriculomegaly or normal scans (90%). Compared with normal cranial ultrasonograms, ventriculomegaly was associated with lower gestational age, male sex, and bronchopulmonary dysplasia, late-onset sepsis, meningitis, necrotizing enterocolitis, and stage 3 retinopathy of prematurity. After adjustment, neonates with ventriculomegaly had higher odds of neurodevelopmental impairment (odds ratio [OR], 3.07; 95% CI, 2.13-4.43), cognitive impairment (OR, 3.23; 95% CI, 2.09-4.99), moderate/severe cerebral palsy (OR, 3.68; 95% CI, 2.08-6.51), death/neurodevelopmental impairment (OR, 2.17; 95% CI, 1.62-2.91), but not death alone (OR, 1.09; 95% CI, 0.76-1.57). Behavioral outcomes did not differ. Conclusions and Relevance Nonhemorrhagic ventriculomegaly is associated with increased odds of neurodevelopmental impairment among extremely preterm neonates.

Objectives To describe the frequency of postnatal discussions about withdrawal or withholding of life-sustaining therapy (WWLST), ensuing WWLST, and outcomes of infants surviving such discussions. We hypothesized that such survivors have poor outcomes. Study design This retrospective review included registry data from 18 centers of the National Institute of Child Health and Human Development Neonatal Research Network. Infants born at 22-28 weeks of gestation who survived >12 hours during 2011-2013 were included. Regression analysis identified maternal and infant factors associated with WWLST discussions and factors predicting ensuing WWLST. In-hospital and 18- to 26-month outcomes were evaluated. Results WWLST discussions occurred in 529 (15.4%) of 3434 infants. These were more frequent at 22-24 weeks (27.0%) compared with 27-28 weeks of gestation (5.6%). Factors associated with WWLST discussion were male sex, gestational age (GA) of ≤24 weeks, birth weight small for GA, congenital malformations or syndromes, early onset sepsis, severe brain injury, and necrotizing enterocolitis. Rates of WWLST discussion varied by center (6.4%-29.9%) as did WWLST (5.2%-20.7%). Ensuing WWLST occurred in 406 patients; of these, 5 survived to discharge. Of the 123 infants for whom intensive care was continued, 58 (47%) survived to discharge. Survival after WWLST discussion was associated with higher rates of neonatal morbidities and neurodevelopmental impairment compared with babies for whom WWLST discussions did not occur. Significant predictors of ensuing WWLST were maternal age >25 years, necrotizing enterocolitis, and days on a ventilator. Conclusions Wide center variations in WWLST discussions occur, especially at ≤24 weeks GA. Outcomes of infants surviving after WWLST discussions are poor. Trial registration ClinicalTrials.gov : NCT00063063 .

Objectives To identify variables associated with successful elective extubation, and to determine neonatal morbidities associated with extubation failure in extremely preterm neonates. Study design This study was a secondary analysis of the National Institute of Child Health and Human Development Neonatal Research Network's Surfactant, Positive Pressure, and Oxygenation Randomized Trial that included extremely preterm infants born at 240/7 to 276/7 weeks' gestation. Patients were randomized either to a permissive ventilatory strategy (continuous positive airway pressure group) or intubation followed by early surfactant (surfactant group). There were prespecified intubation and extubation criteria. Extubation failure was defined as reintubation within 5 days of extubation. Results Of 1316 infants in the trial, 1071 were eligible; 926 infants had data available on extubation status; 538 were successful and 388 failed extubation. The rate of successful extubation was 50% (188/374) in the continuous positive airway pressure group and 63% (350/552) in the surfactant group. Successful extubation was associated with higher 5-minute Apgar score, and pH prior to extubation, lower peak fraction of inspired oxygen within the first 24 hours of age and prior to extubation, lower partial pressure of carbon dioxide prior to extubation, and non-small for gestational age status after adjustment for the randomization group assignment. Infants who failed extubation had higher adjusted rates of mortality (OR 2.89), bronchopulmonary dysplasia (OR 3.06), and death/ bronchopulmonary dysplasia (OR 3.27). Conclusions Higher 5-minute Apgar score, and pH prior to extubation, lower peak fraction of inspired oxygen within first 24 hours of age, lower partial pressure of carbon dioxide and fraction of inspired oxygen prior to extubation, and nonsmall for gestational age status were associated with successful extubation. Failed extubation was associated with significantly higher likelihood of mortality and morbidities. Trial registration ClinicalTrials.gov : NCT00233324 .

There is concern at the National Heart, Lung, and Blood Institute (NHLBI) and among transfusion medicine specialists regarding the small number of investigators and studies in the field of pediatric transfusion medicine (PTM). Accordingly, the objective of this article is to provide a snapshot of the clinical and translational PTM research considered to be of high priority by pediatricians, neonatologists, and transfusion medicine specialists. Included is a targeted review of three research areas of importance: (i) transfusion strategies, (ii) short- and long-term clinical consequences, and (iii) transfusion-transmitted infectious diseases. The recommendations by PTM and transfusion medicine specialists represent opportunities and innovative strategies to execute translational research, observational studies, and clinical trials of high relevance to PTM. With the explosion of new biomedical knowledge and increasingly sophisticated methodologies over the past decade, this is an exciting time to consider transfusion medicine as a paradigm for addressing questions related to fields such as cell biology, immunology, neurodevelopment, outcomes research, and many others. Increased awareness of PTM as an important, fertile field and the promotion of accompanying opportunities will help establish PTM as a viable career option and advance basic and clinical investigation to improve the health and wellbeing of children.

Background The quality of transfused red blood cells (RBCs) to treat anemia depends on its potential for oxygen delivery, governed by two properties: 1) initial posttransfusion recovery and 2) life span of initially surviving RBCs. The latter property is poorly evaluated by the traditional mean potential life span (MPL) or mean cell age (MA), because these parameters do not evaluate how long transfused RBCs remain in circulation. Furthermore, evaluation of MPL is based on two problematic assumptions regarding transfused RBCs: 1) they were produced at a constant steady-state rate and 2) they have similar storage life spans. Study Design and Methods This work introduces a new parameter, the mean remaining life span (MRL) to quantify transfused RBC survival (TRCS) and presents a simple algorithm for its evaluation. The MRL was calculated for four adult subjects with sickle cell disease and four adult diabetic and nondiabetic subjects using RBC survival data sets with existing TRCS parameters. Results The RBC survival curves in the sickle cell subjects were nonlinear with rapid decline in survival within the first 5 days. The MRL was approximately 4.6 days. Thus, the MRL was indicative of the survival of all transfused RBCs. For the diabetic and nondiabetic subjects, the RBC disappearance curves did not deviate substantially from a linear decline. Thus, the estimates for MRL ranging from 39 to 51 days are similar to the MA previously computed. Conclusion MRL overcomes limitations of previously proposed TRCS parameters, is simpler to calculate, and is physiologically and clinically more appropriate.

Objective To determine the impact of policy changes for pulse oximetry oxygen saturation (SpO2) alarm limits on neonatal mortality and morbidity among infants born very preterm. Study design This was a retrospective cohort study of infants born very preterm in the Eunice Kennedy Shriver National Institute of Child Health and Human Development Neonatal Research Network. Infants were classified based on treatment at a hospital with an SpO2 alarm policy change and study epoch (before vs after policy change). We used a generalized linear mixed model to determine the effect of hospital group and epoch on the primary outcomes of mortality and severe retinopathy of prematurity (ROP) and secondary outcomes of necrotizing enterocolitis, bronchopulmonary dysplasia, and any ROP. Results There were 3809 infants in 10 hospitals with an SpO2 alarm policy change and 3685 infants in 9 hospitals without a policy change. The nature of most policy changes was to narrow the SpO2 alarm settings. Mortality was lower in hospitals without a policy change (aOR 0.63; 95% CI 0.50-0.80) but did not differ between epochs in policy change hospitals. The odds of bronchopulmonary dysplasia were greater for hospitals with a policy change (aOR 1.65; 95% CI 1.36-2.00) but did not differ for hospitals without a policy change. Severe ROP and necrotizing enterocolitis did not differ between epochs for either group. The adjusted odds of any ROP were lower in recent years in both hospital groups. Conclusions Changing SpO2 alarm policies was not associated with reduced mortality or increased severe ROP among infants born very preterm.

Studies published 27 years ago showed that erythroid progenitor cells of preterm neonates were responsive to recombinant erythropoietin (Epo).1 Many clinical trials were subsequently performed worldwide, testing whether administering Epo to preterm infants might be a safe and effective way to expand their red cell mass and decrease their transfusion requirements. Indeed, essentially all trials convincingly showed that Epo can stimulate erythropoiesis in preterm and term infants, and has the capability to diminish donor exposure and decrease transfusions. Recent randomized, multi-centered, placebo-controlled trials of erythropoiesis stimulating agents (ESAs), such as Epo or longer acting darbepoetin, administered to preterm infants also show a reduction in blood donor exposure and a lower transfusion rate.2 Along with the clinical trials aimed at decreasing or eliminating transfusions, animal studies have shown that ESAs have neuroprotective effects, thought to be in part the result of ESA’s inhibition of apoptosis. These encouraging findings paved the way for clinical trials that are currently underway, evaluating clinically relevant neurodevelopment effects of ESAs in high-risk neonatal populations. Higher doses of ESAs than those used in stimulating erythropoiesis have been proposed to achieve Epo concentrations capable of crossing the blood brain barrier to produce therapeutic levels in the brain. Doses from 1000 to 3000 units/kg have been evaluated in pilot studies of preterm infants3,4 and in term neonates receiving therapeutic hypothermia for hypoxic ischemic encephalopathy.5 Darbepoetin has been evaluated in term neonates with hypoxic ischemic encephalopathy being cooled,6 and in preterm infants to improve neurocognitive outcomes,7 with encouraging neurodevelopmental results. Although the most effective neuroprotective dose and dosing intervals of these ESAs have yet to be determined, evidence is accumulating that ESAs have favorable neuroprotective effects in both preterm7,8 and term infants.9 In this issue of The Journal, Fauchere et al report hospital outcomes of a randomized clinical trial testing high dose Epo in preterm infants.10 Although results of the primary outcome of the study—neurodevelopment at 24 months—are pending, a subset of infants enrolled in the study had magnetic resonance imaging at term-corrected age, which showed that the infants treated with Epo had lower white and grey matter injury scores.11 In the current study, over 450 infants were randomized in masked fashion to receive placebo (NaCl 0.9%) or intravenous Epo, 3000 units/kg administered at 3, 12–18, and 36–42 hours after birth. This initial report focused on the safety of early high dose Epo, and followed the hospital course of all enrollees. No safety issues were identified. Specifically, there were no differences in the occurrence of any intracranial hemorrhage (11.4% in the Epo-treated group vs 9.6% in the placebo group) or of retinopathy of prematurity (ROP). The overall incidence of any stage ROP in the Epo treated group was 9.5% (1.9% for ROP ≥stage 3), vs 10.2% (3.7% for ROP ≥stage 3) in the placebo group. The safety data are reassuring both to Epo investigators evaluating potential neuroprotective effects, and to clinicians currently using Epo to avoid transfusions in preterm infants.10 Although early studies of Epo administered to preterm infants were promising, meta-analyses published in 200612,13 reversed the trend of Epo use in many neonatal intensive care units. The authors of the 2006 reviews separated Epo studies into early (first week of life) and late (after the first week) administration, and concluded that the incidence of ≥stage 3 ROP was increased with early Epo administration. Only 1 study in this meta-analysis reported an increase in ROP among recipients of Epo, a single-center study by Romagnoli et al.14 In revised meta-analyses15,16 of the 27 studies randomizing 2209 infants to early Epo or placebo, the incidence of ROP was reported in 7 studies, comprising only 36% of all study infants. Despite their initial report in 2000, Romagnoli et al continued to study Epo,17 and Epo is currently standard of care in their unit.17 Currently, ample evidence exists that administering ESAs to selected neonatal populations significantly diminishes transfusion requirements and blood donor exposures, reduces transfusion costs, and conserves blood bank resources.18,19 In addition, there is mounting evidence—bolstered by recent studies including this study by Fauchere et al—indicating that early Epo administration to preterm neonates does not increase their risk for developing ROP or any other complications of prematurity. We eagerly await the long-term follow-up results of this and other studies such as the Preterm Erythropoietin for Neuroprotection (PE-NUT) study to determine whether high dose ESAs are also neuroprotective.

Preterm very-low-birth-weight (VLBW) infants weighing1.5 kg at birth develop anemia, often requiring multiple red blood cell transfusions (RBCTx). Because laboratory blood loss is a primary cause of anemia leading to RBCTx in VLBW infants, our purpose was to simulate the extent to which RBCTx can be reduced or eliminated by reducing laboratory blood loss in combination with pharmacodynamically optimized erythropoietin (Epo) treatment.Twenty-six VLBW ventilated infants receiving RBCTx were studied during the first month of life. RBCTx simulations were based on previously published RBCTx criteria and data-driven Epo pharmacodynamic optimization of literature-derived RBC life span and blood volume data corrected for phlebotomy loss.Simulated pharmacodynamic optimization of Epo administration and reduction in phlebotomy by ≥ 55% predicted a complete elimination of RBCTx in 1.0-1.5 kg infants. In infants1.0 kg with 100% reduction in simulated phlebotomy and optimized Epo administration, a 45% reduction in RBCTx was predicted. The mean blood volume drawn from all infants was 63 ml/kg: 33% required for analysis and 67% discarded.When reduced laboratory blood loss and optimized Epo treatment are combined, marked reductions in RBCTx in ventilated VLBW infants were predicted, particularly among those with birth weights1.0 kg.

Background Anemia, a common condition among critically ill premature infants, is affected by red blood cell (RBC) survival (RCS). We hypothesized that transfused allogeneic Kidd antigen mismatched RBCs would demonstrate the same concurrent RCS tracking as RBCs multi-labeled at separate, discrete low densities with biotin (BioRBCs). Methods Allogeneic RBCs from adult donors were labeled at four biotin densities, mixed, and transfused into 17 anemic premature infants. Nine of the donors and neonates were Kidd antigen mismatched. Serial post-transfusion blood samples were assayed for up to eight weeks by flow cytometry to track the survival of the proportions of Kidd antigen mismatched and biotinylated RBCs. Results Using linear mixed modeling to compare results, RCS of the three lowest BioRBC densities was similar to RCS by Kidd antigen mismatch and to one another. RCS of RBCs labeled at the highest BioRBC density was shortened. Conclusions RCS of different populations of RBCs can be tracked concurrently and reliably using the three lowest BioRBC densities. Although comparable RCS results can be achieved using Kidd antigen mismatches, BioRBCs are preferred for investigating neonatal anemias because biotin labeling of both allogeneic and autologous RBCs is possible.

Study of the pathophysiology and treatment of anemia of prematurity is facilitated by direct measurement of red cell volume (RCV) utilizing microliter quantities of blood samples. Our objective was to compare concurrent measurements of multiple direct RCV methods in infants.Eighteen preterm infants receiving clinically indicated transfusions had concurrent flow cytometric determinations of RCV and 24-h red blood cell (RBC) recovery based on donor-recipient differences of biotin-labeled RBCs (BioRBCs), Kidd antigen mismatched RBCs, and fetal hemoglobin-positive (HbF(+)) RBCs. High-performance liquid chromatography (HPLC) was also used for measuring HbF and adult hemoglobin protein concentrations for the determination of RCV.Concurrent RCV measurements using BioRBCs (18 and 54 µg/ml), Kidd antigen, and HbF flow cytometry were not statistically different compared with RCVs measured using the reference BioRBC density (6 µg/ml). By contrast, the HbF-HPLC method overestimated RCV by 45% compared with the reference method. All the methods demonstrated 100% 24-h posttransfusion RBC recovery (PTR24).Because BioRBC, Kidd antigen, and fetal hemoglobin (HbF) flow cytometry are safe and accurate methods requiring10 µl of patient blood for determining RCV and PTR24 in preterm infants, they can be useful in clinical and research studies of anemia and other conditions.

Biotin-labeled red blood cells (BioRBCs) are used for in vivo kinetic studies. Because BioRBC dosing occasionally induces antibodies, a sensitive and specific anti-BioRBC detection assay is needed.Aims were to 1) develop a gel card assay to evaluate existing, naturally occurring and BioRBC-induced plasma antibodies, 2) compare gel card and tube agglutination detection results, and 3) test for a relationship of antibody induction and BioRBC dose. Reagent BioRBCs were prepared using sulfo-NHS biotin ranging from densities 18 (BioRBC-18) to 1458 (BioRBC-1458) µg/mL RBCs.Among BioRBC-exposed subjects, gel card and tube agglutination results were concordant in 21 of 22 adults and all 19 infant plasma samples. Gel card antibody detection sensitivity was more than 10-fold greater than tube agglutination. Twelve to 16 weeks after BioRBC exposure, induced anti-antibodies were detected by gel card in three of 26 adults (12%) at reagent densities BioRBC-256 or less, but in none of 41 infants. Importantly, induced anti-BioRBC antibodies were associated with higher BioRBC dose (p = 0.008); no antibodies were detected in 18 subjects who received BioRBC doses less than or equal to BioRBC-18. For noninduced BioRBC antibodies, six of 1125 naïve adults (0.3%) and none of 46 naïve infants demonstrated existing anti-BioRBC antibodies using reagent BioRBC-140 or -162. Existing anti-BioRBCs were all neutralized by biotin compounds, while induced antibodies were not.The gel card assay is more sensitive than the tube agglutination assay. We recommend reagent BioRBC-256 for identifying anti-BioRBCs. Use of a low total RBC biotin label dose (≤ BioRBC-18) may minimize antibody induction.

Objective To characterize actual achieved patterns of oxygenation in infants born appropriate vs small for gestational age (SGA) randomized to a lower (85-89%) vs higher (91%-95%) oxygen saturation target in the Surfactant Positive Pressure and Oxygen Trial. To determine the association between achieved oxygen saturation levels and survival in infants born appropriate vs SGA enrolled in the Surfactant Positive Pressure and Oxygen Trial. Study design Median oxygen saturation and intermittent hypoxemia events ( 0/7 -27 6/7 weeks of gestation while receiving supplemental oxygen during the first 3 days of life. Results Lower target infants who were small for gestational age had the lowest oxygen saturation and highest incidence of intermittent hypoxemia during the first 3 days of life. The lowest quartile of oxygen saturation (≤92%) during the first 3 days of life was associated with lower 90-day survival for both infants born appropriate and SGA. An increased incidence of intermittent hypoxemia events during the first 3 days of life was associated with lower 90-day survival only in infants born SGA. Conclusion Lower achieved oxygen saturation during the first 3 days of life was associated with lower 90-day survival in extremely preterm infants. Infants born SGA had enhanced vulnerability to lower oxygen saturation targets as evidenced by lower achieved oxygen saturation and an association between increased intermittent hypoxemia events and lower survival. Trial registration ClinicalTrials.gov: NCT00233324.

Background Prior conclusions that autologous neonatal red blood cells (RBC) have substantially shorter lifespans than allogeneic adult RBCs were not based on direct comparison of autologous neonatal vs. allogeneic adult RBCs performed concurrently in the same infant. Biotin labeling of autologous neonatal RBCs and allogeneic adult donor RBCs permits concurrent direct comparison of autologous vs. allogeneic RBC lifespan. Methods RBCs from 15 allogeneic adult donors and from 15 very low birth weight (VLBW) neonates were labeled at separate biotin densities and transfused simultaneously into the 15 neonates. Two mathematical models that account for the RBC differences were employed to estimate lifespans for the two RBC populations. Results Mean±SD lifespan for adult allogeneic RBC was 70.1±19.1 d, which is substantially shorter than the 120 d lifespan of both autologous and adult allogeneic RBC in healthy adults. Mean±SD lifespan for neonatal RBC was 54.2±11.3 d, which is only about 30% shorter than that of the adult allogeneic RBCs. Conclusion This study provides evidence that extrinsic environmental factors primarily determine RBC survival (e.g., small bore of the capillaries of neonates, rate of oxygenation/deoxygenation cycles) rather than factors intrinsic to RBC.

Critically ill preterm and term neonates are at high risk for negative iron balance due to phlebotomy that occurs with frequent laboratory monitoring, and the high iron demand of rapid growth. Understanding the prioritization of iron between red blood cells (RBCs) and brain is important given iron’s role in neurodevelopment. Ten neonatal twin lamb pairs (n = 20) underwent regular phlebotomy for 11 d. Lambs were randomized to receive no iron or i.v. daily iron supplementation from 1 to 5 mg/kg. Serum hemoglobin concentration and reticulocyte count were assayed, iron balance calculated, and iron content of RBCs, liver, brain, muscle, and heart measured at autopsy. Among phlebotomized lambs: (i) liver iron concentration was directly related to net iron balance (r = 0.87; P < 0.001) and (ii) brain iron concentration was reduced as a function of net iron balance (r = 0.63) only after liver iron was depleted. In animals with negative iron balance, total RBC iron was maintained while brain iron concentration decreased as a percentage of the iron present in RBCs (r = −0.70; P < 0.01) and as a function of reticulocyte count (r = −0.63; P < 0.05). Phlebotomy-induced negative iron balance limits iron availability to the developing brain.

It is thought that the clearance of transfused red blood cells (RBCs) is related both to the storage time of the transfusion product and to the inflammatory status of the recipient. We investigated these effects in a randomized, "two-hit," healthy volunteer transfusion model, comparing autologous RBCs that were stored for 35 days with those that were stored for 2 days.Healthy male volunteers donated 1 unit of autologous RBCs either 2 days (2D) or 35 days (35D) before the study date. The experiment was started by infusion of 2 ng/kg lipopolysaccharide ("first hit"). Two hours later, the stored RBCs ("second hit") were reinfused, followed by the labeling of RBCs with biotin. Clearance of biotin-labeled RBCs (BioRBCs) was measured during the 5-hour posttransfusion endotoxemia period along with measurements of phosphatidylserine (PS) exposure, lactadherin binding, and expression of CD47 (cluster of differentiation 47; a transmembrane protein encoded by the CD47 gene).In the 2D stored RBCs group, 1.5% ± 3.4% of infused BioRBCs were cleared from the circulation 5 hours posttransfusion versus 4.8% ± 4.0% in the 35D stored RBCs group (p = 0.1). There were no differences in PS exposure, lactadherin binding, or CD47 expression between fresh and stored RBCs or between pretransfusion and posttransfusion measurements.Our study shows a low clearance of RBCs even during endotoxemia. Furthermore, short-term clearance of BioRBCs during endotoxemia was not related to storage duration. Consistent with these observations, PS exposure, lactadherin binding, and CD47 expression did not differ between 2D and 35D stored cells before or after transfusion. We conclude that, in the presence of endotoxemia, clearance of 35D stored autologous RBCs is not increased compared with 2D stored fresh RBCs.

BACKGROUND: Very preterm infants commonly develop anemia requiring multiple red blood cell transfusions (RBCTx). This is in part attributable to heavy laboratory phlebotomy loss. Quantification of the extent to which laboratory blood loss contributes to anemia sufficient to prompt RBCTx has not been examined. STUDY DESIGN AND METHODS: Twenty-six preterm infants weighing less than 1500 g at birth requiring ventilator support who received one or more RBCTx were intensively studied during the first month of life. Hemoglobin (Hb) loss via laboratory blood loss and RBC senescence and Hb gain from RBCTx were precisely accounted for in a Hb mass balance mathematical model developed to assess the impact of phlebotomy on RBCTx when restrictive RBCTx criteria were applied. RESULTS: Study subjects had a birth weight of 880 ± 240 g (mean ± SD) and a Hb level of 14.4 ± 2.4 g/dL at birth and received 3.81 ± 2.15 RBCTx during the study period. Modeling indicated that even with the total elimination of laboratory phlebotomy loss, a reduction of 41% to 48% in RBCTx was achievable. CONCLUSION: The present modeling results indicate that while phlebotomy reduction can significantly decrease the number of RBCTx administered to preterm infants, total elimination of all RBCTx will likely require other approaches, for example, stimulation of erythropoiesis with erythropoiesis-stimulating agents.

The development of anemia after birth in very premature, critically ill newborn infants is a universal well-described phenomenon. Although preventing anemia in this population, along with efforts to establish optimal red blood cell (RBC) transfusion and pharmacologic therapy continue to be actively investigated, the present review focuses exclusively on nonpharmacological approaches to the prevention and treatment of neonatal anemia. We begin with an overview of topics relevant to nonpharmacological techniques. These topics include neonatal and fetoplacental hemoglobin levels and blood volumes, clinical and laboratory practices applied in critically ill neonates, and current RBC transfusion practice guidelines. This is followed by a discussion of the most effective and promising nonpharmacological blood conservation strategies and techniques. Fortunately, many of these techniques are feasible in most neonatal intensive care units. When applied together, these techniques are more effective than existing pharmacotherapies in significantly decreasing neonatal RBC transfusions. They include increasing hemoglobin endowment and circulating blood volume at birth; removing less blood for laboratory testing; and optimizing nutrition.

All preterm infants develop anemia in the first few weeks of life as a result of multiple physiologic, pathophysiologic, and iatrogenic events (1). Among neonates most critically ill, anemia is greatly exacerbated by frequent physician-ordered laboratory tests (2–4). As treatment for anemia, as many as 80% of very-low-birth-weight infants (VLBW) (weighing less than 1,500 g at birth) and 95% of extremely-low-birth-weight infants (weighing less than 1,000 g at birth) receive one or more red blood cell transfusions (RBCTx (5)). The efficacy of RBCTx, measured in terms of improving tissue oxygenation, is not always apparent. Moreover, RBCTx as given to preterm infants are expensive and can be associated with complications that include microbial infections, retinopathy of prematurity, and electrolyte perturbations (6). The hormone erythropoietin (Epo) stimulates red blood cell (RBC) production and has been investigated as an alternative therapy for the treatment and prevention of neonatal anemia. A meta-analysis of 27 Epo clinical trials in VLBW and extremely-low-birth-weight infants in which the goal was to reduce RBCTx concluded that the effect of Epo in reducing RBCTx in preterm infants was too limited to be of clinical importance (6). However, this conclusion may be challenged for several reasons. First, there are difficulties in combining many clinical trials into a meta-analysis because of the heterogeneity of studies employing different Epo doses and schedules, different routes of Epo administration, different RBCTx criteria, different definitions of success, and different enrollment criteria. Second, the empirical choice of dosing used in some Epo clinical trials is limited because the trials were not designed to recognize the individual responsiveness to Epo treatment (different pharmacodynamics (PD)). An attractive alternative approach to the design of Epo clinical trials in preterm infants is a personalized medicine approach in which Epo’s complex pharmacokinetics (PK) and PD are more fully considered. This powerful PK/PD approach is attractive because it considers how individual infants respond to Epo. Thus, this approach can be used to develop an optimized Epo dosing regimen that both (a) targets subsets of infants predicted to be the most responsive to treatment with Epo and (b) identifies those unlikely to respond. Unfortunately, compared with the extensive Epo PK/PD studies in adults, only limited Epo PK/PD data exist in this difficult-to-study infant patient group. The mechanism of action for the clearance of Epo in both adults and infants has been identified as nonlinear, Epo receptor (EpoR)-mediated endocytosis (5,7–9) followed by lysosomal degradation(10). Determining preterm infants’ PD response to Epo is experimentally demanding because it requires an accurate, real-time evaluation of hemoglobin (Hb) production, a procedure that is greatly impacted by the numerous phlebotomies and RBCTx very premature infants receive (1). Recently, our research group overcame these problems using a mass balance approach to determine Hb production in 14 critically ill VLBW preterm infants studied for factors impacting endogenous erythropoiesis. This approach required meticulous accounting for Hb transfused and Hb removed by phlebotomy for RBC losses caused by senescence and for expanding blood volume as a consequence of growth (11). The sample size was not specifically determined for the present study because this study represents a secondary analysis of data from a yet-to-be published study whose aims/hypothesis required a sample size of 24 VLBW infants.

Characterization of the behavior of red blood cells (RBCs) in the bloodstream after transfusion (i.e., posttransfusion RBC kinetics) generally consists of measurement of RBC volume (RCV) and RBC survival (RCS) assessed by posttransfusion recovery at 24 hours (PTR24) and at later times, that is, to 50% survival (T50) and to the mean potential life span (MPL). Posttransfusion RBC kinetic studies provide information valuable in establishing the diagnosis and defining the pathogenesis of hematologic conditions and in determining optimal RBC transfusion and blood banking practices.1 Ideally, techniques for measuring posttransfusion RBC kinetics should be precise, safe, and easily applied. They should also be broadly applicable to diverse study populations and require minimal blood volumes for sampling, labeling, and analysis—particularly for infants. Methods utilizing chromium-51 (51Cr) radionuclide RBC labeling have been adopted by the International Committee for Standardization in Hematology as the reference method for determining posttransfusion RCS in humans.2 Unfortunately, because some species experience excessive rates of loss of 51Cr from RBCs (3%–4% per day in sheep, horses, cattle, goats, cats, and rats, compared to approx. 1% in humans),3 the 51Cr labeling method is not reliable for all mammalian species. Moreover, the costs for radiation containment and disposal are substantial and increasing. Recently, a method based on biotin-labeled RBCs (BioRBC) that does not require radiation exposure has been developed and validated for use in posttransfusion kinetic studies in a broad spectrum of mammalian species. In addition to overcoming the aforementioned limitations of the 51Cr method, the BioRBC method achieves similar sensitivity while requiring analytic blood volumes as small as 3 μL4,5 compared to the 1 to 2 mL recommended for the 51Cr method.3 The focus of this study was on validating the BioRBC labeling method in sheep. This is important because ovine fetal and newborn cardiovascular, pulmonary, and of relevance for this report, hematologic development and physiology resemble those of humans.6 In particular, ovine erythropoiesis in the fetus, neonate, and adult is similar to the human, and regulation of erythropoiesis and RBC kinetics in the ovine model are currently active areas of study.7–10 Accordingly, lambs and sheep are logical animal models for preclinical testing of this method for measuring RCV and RCS. We recently demonstrated that autologous sheep RBCs labeled at four discrete, low biotin densities yielded RCV results that are equivalent to one another and are within 10% of values determined simultaneously using [14C]cyanate-labeled RBCs.11 Further, we have applied the multidensity method to measurement of RCV in human adults with similar success. We were able to extend these human studies to survival of the BioRBCs and determine short-term and long-term RCS in eight participants. However, use of a radioactive-labeled marker such as 51Cr was not included because of the technical and financial demands. In this study, we extend these preclinical animal studies to assess the validity of RCS determined in the same animals using RBCs labeled with the same four biotin densities and with [14C]cyanate. Because of the additional complexities of dealing with an animal with a large spleen that sequesters up to 30% of RBCs, of the difficulties of measuring radiolabeled RBCs, and the need to fit a mathematical curve to accurately determine the proportion of each of the BioRBC peaks, we have only recently completed this analysis for the current report. To do so, we assessed short-term RCS by PTR24 and long-term RCS by T50 and by MPL. For long-term RCS, we hypothesized that these two variables would agree closely when determined using RBCs labeled with the lower BioRBC densities and that they would agree with RCS determined using [14C]cyanate.12

To test whether infants randomized to a lower oxygen saturation (peripheral capillary oxygen saturation [SpO2]) target range while on supplemental oxygen from birth will have better growth velocity from birth to 36 weeks postmenstrual age (PMA) and less growth failure at 36 weeks PMA and 18-22 months corrected age.We evaluated a subgroup of 810 preterm infants from the Surfactant, Positive Pressure, and Oxygenation Randomized Trial, randomized at birth to lower (85%-89%, n = 402, PMA 26 ± 1 weeks, birth weight 839 ± 186 g) or higher (91%-95%, n = 408, PMA 26 ± 1 weeks, birth weight 840 ± 191 g) SpO2 target ranges. Anthropometric measures were obtained at birth, postnatal days 7, 14, 21, and 28; then at 32 and 36 weeks PMA; and 18-22 months corrected age. Growth velocities were estimated with the exponential method and analyzed with linear mixed models. Poor growth outcome, defined as weight10th percentile at 36 weeks PMA and 18-22 months corrected age, was compared across the 2 treatment groups by the use of robust Poisson regression.Growth outcomes including growth at 36 weeks PMA and 18-22 months corrected age, as well as growth velocity were similar in the lower and higher SpO2 target groups.Targeting different oxygen saturation ranges between 85% and 95% from birth did not impact growth velocity or reduce growth failure in preterm infants.

Red blood cells (RBCs) can be removed from the bloodstream at an accelerated rate by antibody-mediated mechanisms in a number of immunologic conditions including the following: 1) autoimmune hemolytic anemias, 2) transfusion of incompatible allogeneic RBCs into a recipient whose blood contains a corresponding alloantibody, 3) transfusion of passive antibodies into a recipient whose RBCs express the cognate antigen, 4) transplacental transfer of maternal allogeneic RBC antibodies into a fetus with RBCs expressing the cognate antigen resulting in alloimmune hemolytic disease of the fetus and newborn, and 5) posttransplantation transfer of viable donor lymphocytes capable of producing antibodies directed against recipient RBCs (e.g., group O donor into group A recipient). When caring for patients with these disorders, having an accurate and safe method for determining in vivo RBC kinetics would be of considerable value for establishing the diagnosis, defining the pathophysiology, and assessing the response to therapy. The availability of RBC survival (RCS) methods that address safety issues (e.g., avoidance of radioactivity) is particularly important for vulnerable patient populations including fetuses, neonates, children, and pregnant women. Direct assessment of RCS requires the ability to distinguish cohort-labeled RBCs from the remaining RBCs in the circulation and to express their number as the relative proportion of labeled RBCs to total RBCs in that blood sample. The internationally recognized reference method for measuring RCS uses autologous or allogeneic RBCs labeled with chromium 51 (51Cr) and is based on concentration of 51Cr per unit volume of blood.1 Because transfusion of 51Cr-labeled RBCs exposes the recipient to radiation, this approach is viewed as unacceptable for research studies in the human fetus, neonate, and pregnant woman. Our laboratory and others2-4 have developed methods for measuring RCS in humans based on labeling of RBCs with biotin at one5-10 or more11 densities. Here the term density refers to biotin labels per RBC and is determined by our selection of the concentration of biotinylating reagent per milliliter of RBCs in the biotinylation reaction mixture. Biotin-labeled RBCs (BioRBCs) are quickly and easily enumerated by flow cytometry.11 The biotin RBC method has the following safety and technical advantages over the standard 51Cr method: 1) study subjects including vulnerable populations are not exposed to radiation; 2) small blood volumes (e.g., 20 μL) are required for monitoring; and 3) multiple, independent RCS measurements can be made simultaneously in the same individual by labeling RBCs at more than one biotin density. The aim of this study was to determine whether RBCs labeled with biotin at a single density can be used to accurately measure shortened RCS of RBCs experimentally coated (opsonized) with antibody simulating the situation present in immune-mediated hemolytic anemia. We hypothesized that short-term and long-term RCS measured using BioRBCs would agree with RCS determined using RBCs labeled with 51Cr.

The two erythropoiesis stimulating agents (ESAs), short acting recombinant human erythropoietin (EPO) and long acting continuous erythropoietin receptor activator (CERA), have been hypothesized to share an in vivo elimination pathway that involves binding to erythropoietin receptor (EPOR) and subsequent internalization. A physiologically based recirculation model and a pharmacokinetic tracer interaction methodology (TIM) were used to compare the in vivo interaction kinetics with EPOR between the two ESAs in adult sheep. Animals treated with EPO experienced a greater EPOR up-regulation than those treated with CERA, as evidenced by an eightfold-higher initial EPOR normalized production rate constant, k(syn) /R(0) , versus a twofold-larger EPOR degradation rate constant, k(deg) . In agreement with in vitro studies, EPO had a lower in vivo equilibrium dissociation constant from EPOR than CERA (K(D) = 6 versus 88.4 pmol/l, respectively, p < 0.01). The internalization and/or degradation of the EPO-EPOR complex was faster than that of the CERA-EPOR complex (k(int) = 24 versus 2.41 h(-1) , respectively, p < 0.01). The adopted model enables a mechanism-based explanation for CERA's slower elimination and greater erythropoietic activity in vivo. As predicted by the model, the slower elimination of CERA is due to: (1) less EPOR up-regulation induced by CERA administration; (2) slower binding of CERA to EPOR; and (3) reduced internalization and/or degradation rate of surface-bound CERA. Slower CERA/EPOR complex elimination explains the greater in vivo erythropoiesis reported for CERA, despite its lower affinity to EPOR. A sensitivity analysis showed that the model parameters were reliably estimated using the TIM methodology.

BACKGROUND: Anemia is a serious problem in critically ill neonates. To investigate the pathophysiology of anemia and responses to red blood cell (RBC) transfusions and erythropoietin therapy, repeated measurement of red blood cell volume (RCV) and blood volume is useful. To extend our previous sheep study in which RBCs were labeled at four different biotin densities, we assessed the validity of this multidensity method for in vivo measurement of circulating RCV in humans. STUDY DESIGN AND METHODS: In eight healthy adults, autologous RBCs were biotinylated at each of four biotin densities (6, 18, 54, and 162 µg biotinylation reagent/mL RBC), mixed, and infused intravenously; blood was sampled at 10, 20, and 60 minutes. At each time, RCV was calculated from dilution of individual RBC populations enumerated by flow cytometry. RCV measurements from the population of RBCs biotinylated at 6 µg/mL were chosen as the reference values because this density had been previously validated against the 51Cr method in vitro and in vivo in humans. RESULTS: Values for RCVs were not significantly different among the four densities of biotinylated RBCs at any of the three time points and did not change over 60 minutes. CONCLUSIONS: These studies provide evidence that four densities of biotinylated RBCs can be used in vivo for simultaneous, independent, accurate measurements of RCV in humans. We speculate that this method will also be useful for repeated measurement of RCV and blood volume in infants and other patient populations in whom radioactive labels should be avoided.

Objective The safe lower limit of haematocrit or haemoglobin that should trigger a red blood cell (RBC) transfusion has not been defined. The objective of this study was to examine the physiological effects of anaemia and compare the acute responses to transfusion in preterm infants who were transfused at higher or lower haematocrit thresholds. Methods The authors studied 41 preterm infants with birth weights 500–1300 g, who were enrolled in a clinical trial comparing high (‘liberal’) and low (‘restrictive’) haematocrit thresholds for transfusion. Measurements were performed before and after a packed RBC transfusion of 15 ml/kg, which was administered because the infant9s haematocrit had fallen below the threshold defined by study protocol. Haemoglobin, haematocrit, RBC count, reticulocyte count, lactic acid and erythropoietin were measured before and after transfusion using standard methods. Cardiac output was measured by echocardiography. Oxygen consumption was determined using indirect calorimetry. Systemic oxygen transport and fractional oxygen extraction were calculated. Results Systemic oxygen transport rose in both groups following transfusion. Lactic acid was lower after transfusion in both groups. Oxygen consumption did not change significantly in either group. Cardiac output and fractional oxygen extraction fell after transfusion in the low haematocrit group only. Conclusions These study9s results demonstrate no acute physiological benefit of transfusion in the high haematocrit group. The fall in cardiac output with transfusion in the low haematocrit group shows that these infants had increased their cardiac output to maintain adequate tissue oxygen delivery in response to anaemia and, therefore, may have benefitted from transfusion.

BACKGROUND Safe, accurate methods permitting simultaneous and/or repeated measurement of red blood cell (RBC) survival (RCS) are important to investigate pathophysiology and therapy of anemia. Methods using chromium 51 (51Cr) -labeled RBCs are unacceptable for infants, children, and pregnant women. We report RCS measured in vivo using RBCs labeled with several densities of biotin (BioRBCs).

OBJECTIVE: To identify rates of overweight (BMI ≥85(th) percentile) and obesity (BMI ≥95(th) percentile) at 6-7 years of age and associated risk factors among extremely preterm infants born at < 28 weeks of gestation. STUDY DESIGN: Anthropometrics, blood pressure, and active and sedentary activity levels were prospectively assessed. Three groups were compared, those with BMI≥85(th) percentile (overweight or obese for age, height and sex) and ≥95(th) percentile (obese) versus 85(th) percentile), central fat (waist circumference> 90(th) percentile), spent more time in sedentary activity (20.5 versus 18.2 versus 16.7 hours/week), and had either systolic and/or diastolic hypertension (24% versus 26% versus 14 %) respectively. Post discharge weight gain velocities from 36 weeks postmenstrual age (PMA) to 18 months, and 18 months to 6-7 years were independently associated with BMI ≥85(th) percentile whereas weight-gain velocity from 18 months to 6-7 years was associated with obesity. CONCLUSIONS: One in five former extremely preterm infants is overweight or obese and has central obesity at early school age. Post discharge weight gain velocities were associated with overweight and obesity. These findings suggest the obesity epidemic is spreading to the most extremely preterm infants. Trial registration ClinicalTrials.gov NCT00063063 and NCT0000

BACKGROUND: To investigate the pathophysiology of anemia and responses to red blood cell (RBC) transfusions and erythropoietin, repeated measurement of the circulating red blood cell volume (RCV) would be useful. Ovine erythropoiesis is similar to human erythropoiesis. Accordingly, a method for measuring RCV using either human or sheep RBCs labeled at different biotin densities has been previously validated in vitro. Here preclinical studies validating this method for in vivo measurement of circulating RCV in sheep are reported. STUDY DESIGN AND METHODS: For each sheep, autologous RBCs were biotinylated were at four discrete densities (12, 24, 48, and 96 µg biotinylation reagent/mL RBCs). The densities were mixed and infused intravenously. Blood was sampled five times over 1 hour beginning at 4 minutes. RCV values were determined based on dilution of each population of biotinylated RBCs and by the [14C]cyanate method. RESULTS: There was no difference among RCVs measured at all densities through 16 minutes; however, by 60 minutes, RBCs biotinylated at the highest density overestimated RCV by 7.6%. RCV values increased 41% over the hour, consistent with equilibration with a pool of RBCs sequestered in the spleen. RCV by the [14C]cyanate method paralleled results by the biotin method but averaged 8% greater. CONCLUSIONS: These studies provide evidence that all four densities of biotinylated RBCs can be used in sheep to simultaneously and independently determine RCV. We speculate that the multidensity biotinylation method will be useful both for multiple simultaneous measurements and for repeated measurement of circulating RCV and blood volume in humans.