Erythropoietin to prevent and treat the anemia of prematurity

Characterization of Neutropenia in Preterm Neonates Following Administration of Darbepoetin Alfa

OBJECTIVE

This study is to evaluate the effects of darbepoetin alfa (darbe) on neutrophil count in preterm neonates treated for anemia of prematurity.

METHODS

This was a retrospective chart review comparing the absolute neutrophil counts (ANCs) of neonates administered 2 doses of subcutaneous darbe 10 mcg/kg to that of a randomly selected comparator group of neonates not administered the drug. Neonates <34 weeks gestational age, gestational age between 23w1d and 33w4d, born between July 2016 and June 2019, were included in the study.

RESULTS

The ANCs of 45 darbe-treated neonates compared with those of 45 randomly selected comparator control neonates revealed no difference in the rate of occurrence of neutropenia (ANC ≤1000/μL) between the darbe-treated neonates (26.7%) and comparator neonates (24.4%) (p > 0.99). There was also no difference in the rate of occurrence of severe neutropenia (ANC ≤500/μL) between the darbe-treated neonates (11.1%) and comparator neonates (6.7%) (p = 0.70). Darbepoetin alfa did not lead to differences in rates of resolution of neutropenia or severe neutropenia.

CONCLUSIONS

Short-term administration of darbe did not affect the ANCs of preterm neonates treated for anemia of prematurity. There was no difference in the rates of occurrence of neutropenia, severe neutropenia, or resolution of either between the darbe-treated neonates and comparator neonates.

Anemia and transfusion in critically ill pediatric patients: a review of etiology, management, and outcomes

This article describes the incidence and etiology of anemia in critically ill children. In addition, the article details the pathophysiology and clinical ramifications of anemia in this population. The use of transfused packed red blood cells as a therapy for anemia in critically ill patients is also discussed, including the indications for and complications associated with this practice as well as potential reasons for these complications. Finally, the article lists some therapeutic practices that may lessen the risks associated with transfusion, and briefly discusses the use of blood substitutes.

Necrotizing enterocolitis and the role of anemia of prematurity

Necrotizing enterocolitis (NEC) is one of the most common surgical diseases of preterm infants, with significant short- and long-term morbidity and mortality. Although the etiology of NEC remains elusive, multiple factors adversely affecting the intestinal mucosal integrity of preterm infants are known to be associated with NEC. Anemia and red blood cell (RBC) transfusion-related gut injury have been shown to have strong correlation with NEC. Anemia potentially compromises mucosal integrity with subsequent poor healing, and this injury may be augmented by yet unknown factors associated with RBC transfusions. Although convincing evidence is lacking, there is a need for guidelines to keep the hematocrit within clinically and physiologically relevant limits by appropriate interventions. Further investigations need to focus on assessing the interplay between anemia, chronically hypoxemic/hypoperfused intestines, and early iron therapy or other pharmacologic approaches for prevention/treatment of anemia and RBC transfusions.

Red blood cell transfusions in newborn infants: Revised guidelines

In general, health care professionals taking care of high risk infants in neonatal intensive care units have become more restrictive in their use of red blood cell transfusion over the past 10 years. The present statement is intended for those caring for high risk newborn infants (preterm to one month of age). The objectives of this statement are to provide guidelines to reduce the incidence of anemia in preterm and term infants, to identify strategies to decrease the need for red blood cell transfusions and to limit donor exposure in this population. Recommendations for red blood cell transfusions are included.

Association of necrotizing enterocolitis with anemia and packed red blood cell transfusions in preterm infants

OBJECTIVE

To determine association of anemia and red blood cell (RBC) transfusions with necrotizing enterocolitis (NEC) in preterm infants.

STUDY DESIGN

A total of 111 preterm infants with NEC ≥ stage 2a were compared with 222 matched controls. In all, 28 clinical variables, including hematocrit (Hct) and RBC transfusions were recorded. Propensity scores and multivariate logistic regression models were created to examine effects on the risk of NEC.

RESULT

Controlling for other factors, lower Hct was associated with increased odds of NEC (odds ratio (OR)=1.10, P=0.01). RBC transfusion has a temporal relationship with NEC onset. Transfusion within 24 h (OR=7.60, P=0.001) and 48 h (OR=5.55, P=0.001) has a higher odds of developing NEC but this association is not significant by 96 h (OR=2.13, P=0.07), post-transfusion.

CONCLUSION

Anemia may increase the risk of developing NEC in preterm infants. RBC transfusions are temporally related to NEC. Prospective studies are needed to better evaluate the potential influence of transfusions on the development of NEC.

Anemia in the preterm infant: erythropoietin versus erythrocyte transfusion--it's not that simple

Since the late 1980s recombinant human erythropoietin (r-EPO) has been studied as an alternative to packed red blood cell (RBC) transfusion for the treatment of anemia of prematurity in very low birth weight infants. Initial trials and reports focused on r-EPO's ability to prevent or treat anemia of prematurity with the goal of eliminating RBC transfusion but achieved limited success. New concerns about the safety of r-EPO administration have emerged. Past cost-benefit analyses of r-EPO administration versus transfusion for the treatment of anemia of prematurity have been nearly balanced. Autologous transfusion, blood-sparing technologies, changes in RBC transfusion technique and safety, and further elucidation of the risk-benefit ratio of r-EPO therapy may change the cost-benefit analysis.

Anemia in the preterm infant: erythropoietin versus erythrocyte transfusion--it's not that simple

Since the late 1980s recombinant human erythropoietin (r-EPO) has been studied as an alternative to packed red blood cell (RBC) transfusion for the treatment of anemia of prematurity in very low birth weight infants. Initial trials and reports focused on r-EPO's ability to prevent or treat anemia of prematurity with the goal of eliminating RBC transfusion but achieved limited success. New concerns about the safety of r-EPO administration have emerged. Past cost-benefit analyses of r-EPO administration versus transfusion for the treatment of anemia of prematurity have been nearly balanced. Autologous transfusion, blood-sparing technologies, changes in RBC transfusion technique and safety, and further elucidation of the risk-benefit ratio of r-EPO therapy may change the cost-benefit analysis.

Erythropoietin protects against necrotizing enterocolitis of newborn rats by the inhibiting nitric oxide formation

BACKGROUND

Necrotizing enterocolitis (NEC) is an important neonatal disease with a high mortality rate; erythropoietin (Epo) is a hematopoietic growth factor. Functional Epo receptors are in the fetal and postnatal small bowel and their ligands are available for binding. Excessive nitric oxide (NO) production by an isoform of NO synthase inducible by inflammatory stimuli leads to changes in vascular permeability and tissue injury. The aim of this study was to investigate NO formation in an experimental model of NEC and the possible role of NO in the protection Epo provides against NEC.

METHODS

Twenty-four Wistar albino rat pups were divided into three groups: group 1 = control; group 2 = hypoxia-reoxygenation and saline; group 3 = hypoxia-reoxygenation and recombinant human EPO (rhEpo) pretreatment. rhEpo was given 750 U/kg/week by intraperitoneal injection 3 times a week for 2 weeks. On the 15th day, hypoxia was induced by placing the pups in a 100% CO(2) chamber for 5 min. After the hypoxia period the pups were reoxygenated for 10 min with 100% O(2) and returned to their mothers. All pups were killed 4 h after the hypoxia-reoxygenation period was over. The abdomen was opened and representative samples of injured areas were taken for histopathologic examination. Then nitrite levels were determined in the intestine by Griess Reagent.

RESULTS

On histopathological examination, injury scores in group-2 animals were found to be significantly higher than in group-3 animals (p = 0.001). Significantly increased intestinal nitrite levels were found in group-2 rats compared to the rats of groups 1 and 3 (p = 0.001 and p = 0.001, respectively). There was a positive correlation between the histological findings and the intestinal nitrite levels in group-2 and -3 animals (r = 0.94, p = 0.001; r = 0.99, p = 0.001, respectively).

CONCLUSION

The present study demonstrates that the Epo-pretreated group had decreased levels of NO and limited mucosal necrosis in intestinal tissue samples. We believe that these results deserve further experimental studies in order to elucidate the possible effector mechanisms involved in the inhibitory relationship between Epo, NO and NEC.

Iron status and the treatment of the anemia of prematurity

Many unanswered issues regarding rhEPO therapy in prematurity remain, including which premature infants best respond to rhEPO, what the long-term effect of decreased erythrocyte transfusions is, how nutritional supplementation optimizes the effect of rhEPO, whether or not rhEpo therapy causes iron deficiency later in life, and whether or not it is safe to supplement with parenteral iron. Further study of rhEPO therapy and iron status in prematurity is necessary.

Effect of recombinant erythropoietin on "late" transfusions in the neonatal intensive care unit: a meta-analysis

OBJECTIVES

Using the approach of a meta-analysis, we sought to determine whether the administration of recombinant erythropoietin (rEpo) to very low birth weight (VLBW) infants, after the first week of life, results in fewer "late" transfusions.

STUDY DESIGN AND METHODS

The guidelines set forth by the Cochrane Neonatal Review Group were used to identify all relevant studies. Medline was searched from January 1990 to November of 2000. Studies that used a randomized, placebo-controlled, and double-masked design were deemed acceptable.

RESULTS

Eight studies meet the inclusion criteria. These involved 357 VLBW neonates: 183 rEpo and 174 placebo recipients. The neonates in the rEpo group received fewer erythrocyte transfusions during the study period than did those in the placebo group; the common odds ratio (OR)=0.33; 95% confidence interval (CI) 0.21-0.51. Furthermore, the rEpo effect size was a function of the dose of rEpo administered (p=0.0001).

CONCLUSION

A meta-analysis of the most scientifically rigorous studies on this topic indicates that administration of rEpo to VLBW infants reduces "late" erythrocyte transfusions in a dose-dependent manner.

Red cell mass responses to daily erythropoietin and iron injections in the ovine fetus

OBJECTIVE

Anemic ovine fetuses supplemented with intra-amniotic iron undergo rapid expansion of red cell mass. The present study tested the hypothesis that nonanemic fetuses that were supplemented with daily intra-amniotic iron plus intravascular injections of erythropoietin would experience accelerated erythrocyte production.

STUDY DESIGN

Nine late gestation ovine fetuses received 100 to 120 units of erythropoietin intravascularly plus 10 mg of iron intra-amniotically daily for 7 days (low erythropoietin dose group). Four additional fetuses received 1000 units of erythropoietin plus 10 mg iron daily for the same period (high erythropoietin dose group). Responses were compared with 9 nonsupplemented time-control fetuses. Statistical testing was by 3-factor repeated measures analysis of variance.

RESULTS

Immediately after erythropoietin injection, plasma erythropoietin concentration was elevated approximately 25- and 250-fold in the low and high erythropoietin dose groups, respectively. Erythropoietin returned to basal levels by 24 hours after the injection. Plasma iron concentration increased in the low erythropoietin dose group but not in the control or high erythropoietin dose groups. Reticulocyte index increased in both erythropoietin supplemented groups but not in control fetuses. Hematocrit level increased above control by day 5 in the low erythropoietin dose group and by day 2 in the high erythropoietin dose group. Red cell mass increased significantly on supplement day 7 in the low erythropoietin dose group and on day 5 in the high erythropoietin dose group. Fetal blood gases and pH were unchanged with time in all 3 groups.

CONCLUSION

Although daily combined erythropoietin and iron supplements in nonanemic ovine fetuses significantly increased circulating red cell mass in a dose-dependent manner, this increase was small relative to the rapid expansion of red cell mass previously observed after iron supplementation in fetuses with hemorrhage-induced anemia. We speculate that this difference in response may be due to a combination of rapid fetal clearance of erythropoietin plus a relative insensitivity to erythropoietin caused by the absence of other cytokines, which are elevated during fetal anemia.

Nonerythropoietic roles of erythropoietin in the fetus and neonate

Epo was once regarded as a cytokine with only hematopoietic effects. It is now clear that the distributions of Epo and Epo-R are more widespread in the developing human. Epo-R is widely distributed during early fetal development, leading to speculation that Epo acts in concert with other growth factors to optimize growth and development. Areas in which Epo has important recognized effects are on endothelial cells, and in the developing heart, gastrointestinal tract, and brain. It may also be important in the regulation of vascular growth during the menstrual cycle, and in the stimulation of testosterone production in men. Epo and Epo-R are prominent in the brain during fetal development, leading to speculation that they play an important role in neurodevelopment. There are also promising data regarding rEpo as a possible neuroprotective agent in such conditions as hypoxia, because it decreases programmed cell death induced during such adverse conditions. It is unlikely, however, that rEpo crosses the blood-brain barrier in normal premature infants, and it is not clear whether the CNS effects of rEpo, should it cross the blood-brain barrier, are harmful or beneficial in the setting of a developing brain.

Necrotizing enterocolitis and hematopoietic cytokines

The names of the hematopoietic cytokines are misleading because in addition to their effects on bone marrow and bone marrow-derived cells, they have many diverse effects, including effects on the gastrointestinal tract. These effects may be directly mediated by interaction with specific receptors on gastrointestinal epithelial cells, or they may result from their effects on circulating or bowel wall leukocytes and the cytokines these cells produce. As might be expected of factors largely defined by their effects on inflammatory cells, the hematopoietic cytokines are intimately involved in the processes of bowel injury. Further investigations are needed to define the role of hematopoietic cytokines in the human neonate's balance between local gastrointestinal host defense and bowel wall injury. This could lead to effective strategies for the treatment and prevention of NEC.

Endothelin concentrations in preterm infants treated with human recombinant erythropoietin

BACKGROUND

Increased endothelin-1 (ET-1) production following recombinant erythropoietin (Epo) administration is a presumed etiology for the hypertension reported in some adults. It is unknown whether Epo has similar effects in preterm infants.

METHODS

Serum ET-1 and Epo concentrations were measured prior to study, and following the second and third doses in 20 preterm infants receiving intravenous (IV) or subcutaneous (SC) Epo. Blood pressures were monitored prior to Epo administration and during the first, second, and third dose.

RESULTS

Infants (963 +/- 54 g birth weight, 27.4 +/- 0.6 weeks gestational age, 18 +/- 3 days of life; mean +/- SEM) had baseline Epo concentrations of 5.5 +/- 1.3 mU/ml and ET-1 concentrations below the lower limits of detection (<1 pg/ml). Epo concentrations were 1,848 +/- 274 and 1,672 +/- 295 mU/ml following the second and third IV dose, respectively, while Epo concentrations were 420 +/- 92 and 290 +/- 35 mU/ml after the second and third SC dose, respectively (p < 0.005, SC versus IV). ET-1 concentrations remained below the limits of detection in all but 6 infants, whose concentrations were <3.3 pg/ml. Blood pressures did not increase above baseline in either group during the study period.

CONCLUSION

Despite the wide range of Epo concentrations measured, no correlation was observed between Epo concentrations, ET-1 concentrations, and blood pressure during the 1-week study period. The long-term effects of Epo on ET-1 concentrations and blood pressure in preterm infants require further study.