Red Blood Cells
Red blood cells
(RBCs), also known as packed red blood cells
(pRBCs),
are prepared from whole blood by removing plasma. Patients who benefit
most from the transfusion of RBCs include those with chronic anemia
resulting from kidney failure or gastrointestinal bleeding, and those
with acute blood loss resulting from surgery or trauma. All RBC
transfusions must be ABO compatible with the recipient. Red blood cells
do not provide viable platelets, nor do they provide clinically
significant amounts of coagulation factors. In the additive solutions,
refrigerated RBCs have a storage shelf life of 42 days.
The high numbers of leukocytes remaining in a unit of pRBCs during
the storage process can fragment, deteriorate, and release cytokines,
and they have been implicated as a cause of reactions to a current and
subsequent blood transfusions in some transfusion recipients.
Leukocyte-reduced red blood cells are prepared using special filters and
have special indications.
Leukoreduction Indications
- Prevention of recurrent febrile non-hemolytic transfusion reactions
- Prevention of the transmission of CMV
- Prevention of alloimmunization to donor HLA antigens (i.e. platelet dependent patients who may become refractory to platelet transfusions, and organ/bone marrow transplant candidates)
Leukoreduced RBCs still contain enough leukocytes capable of producing transfusion-associated graft versus host disease (TAGVHD) in susceptible patients. Prevention of TAGVHD can only be accomplished by irradiation of the RBCs unit.
Irradiation Indications:
- Intrauterine transfusions, transfusions to premature or low-birth weight infants (weighing <1200 gm at birth), newborns with erythroblastosis fetalis, and patients with congenital immunodeficiencies.
- Patients with hematologic malignancies, some solid tumors (incl. Hodgkin disease, neuroblastoma, sarcoma).
- Patients undergoing fludarabine therapy (purine analog), bone marrow transplantation or peripheral blood stem cell transplantation.
- Patients receiving granulocyte components, components that are HLA matched, or directed donations (from blood relatives).
Dosage
The volume of one unit of RBCs contains approximately 200mL red blood
cells, 100 mL of an additive solution, and ~30mL plasma, with a
hematocrit approximately 55%.
In the absence of hemorrhage or active bleeding, the initial
recommended dose is one unit for adults and 10mL/Kg for pediatrics with a
reassessment post transfusion to determine the need for additional
RBCs.
One unit of RBCs in an adult and 10mL/Kg in a pediatric patient
will increase the hematocrit by approximately 3% or the hemoglobin by 1
g/dL in a normovolemic patient.