Neonatal and Pediatric Transfusion Medicine

RBC Transfusion Considerations in Neonates

Neonatal RBC transfusion thresholds are not clearly defined, with gestational age, postnatal age, and clinical condition being important considerations. Two randomized control trials (RCTs) (Bell et al. and Kirpalani et al.) comparing liberal to restricted hemoglobin (hb) transfusion thresholds in preterm neonates had conflicting results regarding neurocognitive outcomes, making general recommendations difficult. Two RCTs (one in the United States and one in Europe) are on going to reexamine this question. An additional consideration is that severe anemia (≤8 gm/dL), but not RBC transfusion, was recently shown to be associated with an increased risk of necrotizing enterocolitis.

RBC Product Selection for Neonates

The type of anticoagulant-preservative solution (CPDA-1 with hematocrit ∼70% vs. AS with hematocrit ∼55%–60%) does not pose significant risk to premature infants and neonates when small -volume transfusion (i.e., 10–15 mL/kg of RBCs) is given. Regarding the relative length of storage of products transfused to neonates, a recent RCT demonstrated no difference in outcomes with the use of fresh (≤7 days) versus standard-issue RBCs in premature low-birth-weight infants (age of red blood cells in premature infants trial).

Although the rise in plasma potassium after a small -volume transfusion is minimal, a risk of hyperkalemia in neonates receiving large -volume transfusions from stored units exists. Fresher, washed, or volume-reduced RBCs have lower potassium loads. Large-volume transfusions also increase the risk of citrate toxicity resulting in hypocalcemia; thus, the transfusion recipient’s electrolytes should be carefully monitored.

Neonatal RBC Compatibility Testing

Given that alloimmunization to transfused RBCs in infants under 4 months of age is extremely unusual, AABB Standards require limited pretransfusion testing for neonates. ABO and RhD forward typing must be done once, and neonatal plasma/serum must initially be tested for passively acquired maternal anti-A or anti-B using the antiglobulin phase if non-group-O RBCs are to be transfused. One antibody screen must be performed on a sample from either the neonate or mother to ensure maternal RBC alloantibodies are not present. During a single hospitalization, repeat antibody screens are not necessary (until 4 months of age) if the initial screen is negative. Compatibility testing and repeat ABO/D typing are necessary only in certain circumstances, such as an initial positive antibody screen or passively acquired maternal anti-A or anti-B, respectively.

Neonatal RBC Exchange Transfusion Considerations

Exchange transfusion (ET) is used primarily in neonates with hemolytic disease of the newborn, to decrease bilirubin levels and to remove offending antigen-positive RBCs. Cord bilirubin levels >5 mg/dL, bilirubin levels that rise >1 mg/dL per hour, or indirect bilirubin levels >20 mg/dL are all indications for ET. RBC products used for ET should be irradiated, hemoglobin S-negative, volume reduced, and reconstituted with plasma to a hematocrit of about 50%. Postprocedure labs must be checked to ensure hemoglobin, platelet count, prothrombin time, partial thromboplastin time, and fibrinogen levels are appropriate (see Chapter 50 ).