RBC Replacement Therapy
Red blood cell transfusions are a common therapy in critically ill anemic children. A packed cell product, which comprises the sedimented or centrifuged RBCs from one unit of single-donor whole blood, is the component of choice for replacement therapy during RBC loss (e.g., owing to surgery or trauma) and sporadic transfusion therapy. In recent decades, it has become apparent that the transfusion of allogeneic cellular blood products is associated with deleterious effects caused by the presence of residual leukocytes. These side effects include febrile nonhemolytic transfusion reactions, alloimmunization to human major histocompatibility antigens, the transmission of leukotropic viruses such as CMV with subsequent infection and reactivation, graft-versus-host disease (GVHD), transfusion-associated acute lung injury and transfusion-associated immunomodulation with immunosuppression. This has led to the development and widespread application of methods to selectively reduce the leukocyte content in blood components before they are transfused, and universal prestorage leukoreduction of cellular blood products has been implemented in almost all Western countries. Specialized leukofiltration or apheresis collection devices achieve a greater than 104-fold reduction of leukocyte content in the final blood products. Routine leukoreduction of RBCs to less than 5 × 106 leukocytes per unit reduces the incidence of febrile nonhemolytic reactions and alloimmunization to human major histocompatibility antigens in transfusion-dependent patients, and has been demonstrated to be effective in preventing CMV transmission in neonates. Clinical evidence supports the use of leukoreduced RBCs long term in all transfused children, neonates and patients undergoing surgery for malignancy. The use of CMV-seronegative leukoreduced blood products is recommended in children at high risk, such as those undergoing hematopoietic stem cell transplants, premature infants of CMV-seronegative mothers and children with immune deficiencies. However, leukofiltration is insufficient to ensure the prevention of transfusion-associated GVHD in patients who are at risk owing to immune compromise. Irradiation of blood products is the only currently accepted practice that can effectively prevent GVHD. Ionizing g-radiation at a dose of 2500 cGy is the recommended method to optimize the inactivation of T lymphocytes in blood components, thus preventing post-transfusion donor T-cell proliferation in response to host antigen-presenting cells, which in turn, abrogates GVHD. Because of the wide variety of children who are at risk for GVHD, some transfusion services irradiate all cellular blood products to ensure that no patient develops this fatal consequence of transfusion.
Washing RBCs is uncommon practice and is usually indicated in the event of severe allergic or anaphylactic transfusion reactions to allogeneic plasma proteins. Washing a unit of RBCs with sterile normal saline removes approximately 99% of plasma proteins, electrolytes and antibodies. As the extracellular potassium concentration increases with the duration of RBC storage, small infants may require saline-washed RBCs if freshly collected RBCs are not available for rapid or large-volume transfusions (>20 ml/kg), such as during exchange transfusions or extracorporeal membrane oxygenation procedures.
Whole blood has been used in rare cases of brisk external hemorrhage, major cardiac surgery or for exchange transfusions in newborns for severe hemolytic disease or hyperbilirubinemia. In today's transfusion practice, reconstituted blood (packed RBCs and fresh frozen plasma) should be used for these indications.[19,20]
Pediatr Health. 2010;4(2):201-208. © 2010 Future Medicine Ltd.
Cite this: Transfusions in the Critically Ill Pediatric Patient - Medscape - Apr 01, 2010.