Pediatric Clinics of North America - CIPERJ

426 FASANO & LUBAN
RBCs is decreased compared with nonirradiated RBCs, at 42 days of storage,
the Food and Drug Administration recommends a 28-day expiration
for irradiated RBCs [17]. Potassium and free hemoglobin (Hb) are increased
after irradiation and storage of RBCs. Therefore, it is preferable
to irradiate in a time frame close to administration rather than prolonged
refrigerator storage products, especially for neonates, who may not be
able to tolerate a large potassium load. Irradiation of platelets does not
affect function, and although superoxide production and phagocytic
function is shown to be decreased in granulocytes irradiated at 2500
cGy, most authorities recommend irradiating granulocytes before
administering.
Red blood cell products
RBCs are prepared by removal of 200 to 250 mL of plasma from 1 unit of
WB. RBCs collected in CPDA-1 have a volume of approximately 250 mL
and a hematocrit of 70% to 80%. When RBCs are supplemented with additional
preservative solutions (ie, Adsol, Nutricell, or Optisol) the volume
is increased to approximately 350 mL and the hematocrit is reduced to
50% to 60%. These RBC components have approximately 50 mL of plasma
and the advantage of longer storage shelf life (42 days versus 35 days) and
lower viscosity; therefore, they flow more rapidly than the traditional CPD
and CPDA components. Notice must be taken by today’s practitioners of
the lower hematocrit of the current AP-based RBC products when calculating
Hb increments post transfusion. For example, using the formula: Volume
of RBCs to be transfused ¼ TBV ([desired Hb] [actual Hb])/[Hb]
of RBC unit, where TBV (total blood volume) is 70 to 75 mL/kg by 3 months
of age.
Although approximately 10 mL/kg increases the Hb concentration by
3 g/dL for individuals receiving RBCs in CPDA (hematocrit 69%), approximately
12.5 to 15 mL/kg is necessary to attain the same Hb concentration
increment for individuals receiving RBCs in AS-1 (hematocrit 54%).
In addition to leukocyte reduction and gamma irradiation, RBC products
can be washed using sterile saline to rinse away the remaining plasma
proteins within an RBC unit or frozen using high glycerol concentrations
for long-term storage of RBC units with unique phenotypes. RBC washing
removes plasma proteins, microaggregates, and cytokines and is indicated
for severe, recurrent allergic reactions to blood components despite premedication
with antihistamines, because these reactions usually are the result
of reactions from foreign plasma proteins. Patients who have IgA
deficiency and anti-IgA are at risk for anaphylaxis from donor IgA within
the plasma and may benefit from washed RBCs [18]. RBC washing should
not be considered a substitute for leukoreduction because the washing process
removes by only 1 log versus the 3 to 4 log depletion attained by