(b) As pretransfusion testing of donor blood has become more
complex, the time required to make fresh blood available has increased. It is preferable
to maintain stock supplies of cryoprecipitate, fresh-frozen plasma, or concentrated
coagulation so that patients requiring replacement of platelets, coagulation factors, and
RBCs can be treated with appropriate mixtures of these components. Usually, these
previously tested components can be made available to patients much more rapidly
than fresh WB.
(4) Leukocyte-poor red blood cells. Multiparous women (those who have
had two or more pregnancies resulting in viable fetuses, whether or not the offspring
were alive at birth) or patients who receive multiple transfusions may develop antibodies
to leukocytes and platelets. When patients with leukocyte antibodies receive blood
containing incompatible leukocytes, febrile transfusion reactions may occur. These
leukocyte reactions do not cause red blood hemolysis, but can be extremely
uncomfortable for the patient and are potentially fatal. Symptoms such as chills, fever,
headache, malaise, nausea, vomiting, and chest or back pain may persist for up to 8
hours and seem to be caused by immune damage to donor leukocytes. The frequency
and severity of leukocyte transfusion reaction is directly related to the number of
incompatible leukocytes transfused. Therefore, leukocyte-poor blood (LP-RBCs) is
indicated for patients who have repeated febrile transfusion reactions. Because febrile
reactions occur rather commonly, patients should be switched to leukocyte-pooronly
after they have experienced two or more such reactions.
(5) Frozen Red Blood Cells. The blood bank text written prior to 1978 lists
decreased incidences of post-transfusion hepatitis as an advantage of frozen RBCs.
Alter et al demonstrated in 1978 that human blood in which the plasma was inoculated
before freezing with hepatitis B virus could transfer the virus to chimpanzees after
processing, freezing, and deglycerolization. Deglycerolized RBCs have also been
shown to transmit hepatitis B to human recipients. Retroviruses, such as HIV, are also
likely to be present in a unit of deglycerolized RBCs. Studies are being conducted to
determine if frozen blood cells prevent cytomegalovirus. Glycerolizing and
deglycerolizing RBCs remove granulocytes and platelets, preventing reactions with
granulocytes and platelet antibodies; however, some lymphocytes survive, thus the
potential to cause graft-versus-host reactions may persist. In addition to these specific
indications, the long term shelf life of frozen red cells make them ideal for storage of
rare blood types and for autologous transfusion. The disadvantages of frozen RBCs are
the additional cost and the limited storage period of 24 hours following thawing and
deglycerolization.
MD0846
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