Neonatal transfusion testing, manufacturing, standards, and storage

The neonatal population is a heavily transfused group, particularly very-low-birth weight infants (<1500 g) and extremely low birth weight infants (<1000 g). A neonate is defined as an infant during the period between birth and 4 months. Preterm neonates, defined as infants born before the 37th week of gestation, are one of the most frequently transfused populations in tertiary care centers (Wong E. et al. Pediatric transfusion: a physician’s handbook. Bethesda: AABB; 2015). Given the differences in immunologic status, blood volume, physiologic response to hypovolemia, and heterogeneity of the population, the approach to neonatal transfusion is vastly different from that of any other patient group. This chapter discusses the approaches to blood processing, storage, and distribution and directly addresses special considerations for the modification of blood and blood components for neonates. In particular, obstacles pertaining to neonate size, blood volume, and safety of modified products will be elucidated. In order to understand basic approaches and special requests in this setting, neonatal standards and physiology must first be defined within the subgroup. Full-term neonates have a mean cord blood hemoglobin (Hgb) level of 16.9 ± 1.6 g/dL. Preterm neonates typically are born with lower levels of 15.9 ± 2.4 g/dL (Josephson C, Meyer J Neonatal and pediatric transfusion practice. In: Fung M, Grossman BJ, Hillyer CD, Westhoff C, editors. Technical manual. 18th ed. Bethesda: AABB; 571-597, 2014). During the first few weeks of life, newborns experience a physiologic decline in Hgb levels to as low as 7.0 g/dL seen in extremely low birth rate infants (Josephson C, Meyer J Neonatal and pediatric transfusion practice. In: Fung M, Grossman BJ, Hillyer CD, Westhoff C, editors. Technical manual. 18th ed. Bethesda: AABB; 571-597, 2014; Brugnara C, Platt OS. The neonatal erythrocyte and its disorders. In: Nathan DG, Orkin SH, editors. Nathan and Oskis hematology of infancy and childhood. 7th ed. Philadelphia: WB Saunders; 21-66, 2009). Many factors including frequent blood draw and attenuated erythropoietin production can lead to anemia in the newborn. Current guidelines recommend transfusion for symptomatic anemia with a Hgb <7 and low reticulocyte count (Doyle JJ. The role of erythropoietin in anemia of prematurity. Semin Perinatol; 20-7, 1997; Doyle Semin Perinatol 21:20-27, 1997). Transfusion is recommended at higher hemoglobin levels, <10 g/dL to <12 g/dL, in symptomatic infants on supplemental oxygen, those requiring continuous positive airway pressure (CPAP), significant apnea, bradycardia, tachycardia, or tachypnea and low weight gain. Infants on extracorporeal membrane oxygenation (ECMO) or with congenital cyanotic heart disease may have an even higher hemoglobin threshold at <15 g/dL (Wong E. et al. Pediatric transfusion: a physician’s handbook. Bethesda: AABB; 2015).In the event that transfusion is needed, it is appropriate to treat based on a target Hgb rather than volume replacement of estimated volume lost. However, some Hgb thresholds are based on the presence of respiratory support and postnatal age. Given the need for smaller volumes, the neonatal patient often requires smaller doses of components dispensed as aliquots. Furthermore, given the immaturity of the immune system, particularly in the premature neonate, pretransfusion testing and secondary processing steps must be adjusted to provide the best and safest product (Josephson C, Meyer J. Neonatal and pediatric transfusion practice. In: Fung M, Grossman BJ, Hillyer CD, Westhoff C, editors. Technical manual. 18th ed. Bethesda: AABB; 571-597, 2014; Wang-Rodriguez et al. Transfusion. 40(1):25-34, 2000). The remainder of this chapter will address such adjustments in the manufacturing, storage, processing, and distribution in accordance with standards set by the American Association of Blood Banks (AABB).