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Adverse Outcomes in Blood and Blood Component Therapy - page 7 / 19





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concentration of IL-1 and IL-6 in the plasma supernatant. In vitro studies demonstrated that IL-1 and IL-6 concentrations rise progressively in stored platelets and that these concentrations are related to the leukocyte count in the platelet product. They concluded that the BRMs in the plasma supernatant of the platelet product cause most febrile reactions associated with platelet transfusions and that removing the plasma supernatant before transfusion can minimize or prevent these reactions.22

Aye et al23, investigated whether leukocyte reduction in PCs by filtration significantly reduced the levels of cytokines normally generated during storage of unfiltered PCs up to 5 days. They also measured the levels of serotonin, platelet-derived growth factor (PDGF-), and von Willebrand factor to establish whether or not filtration or storage elicited significant platelet activation and granule release. Their result showed that filtration significantly reduced total leukocyte counts by 99.1 percent before storage without affecting total platelet counts. Compared to unfiltered PCs, filtration prevented a rise in the levels of each cytokine by Day 3 for IL-1 (27.7 vs. 0.6 pg/mL), IL-6 (114.2 vs. 0.4 pg/mL), and IL-8 (4.2 vs. 0.02 ng/mL). By Day 5, they noted further increases in the levels of all cytokines in unfiltered PCs, but Day 0 levels remained in filtered PCs (IL-1: 105.4 vs. 0.4 pg/mL,; TNF-: 42.2 vs. 7.5 pg/mL,; IL-6: 268.8 vs. 0.4 pg/mL,; and IL-8: 7.6 vs. 0.02 ng/mL,). From Day 0 to Day 5, they found significant increases in serotonin (21.3 vs. 6.3 ng/mL), PDGF- (72.6 vs. 25.8 ng/mL), and von Willebrand factor (4.7 vs. 2.7 IU/mL) in unfiltered PCs, with similar increased levels being observed in filtered PCs during storage. They concluded that the accumulation of high levels of cytokines in stored PCs could be prevented by leukocyte reduction filtration of the PCs without the induction of significant platelet activation or granule release. Since cytokines are known to have the potential to induce FNHTRs, the transfusion of leukocyte reduced PCs would be expected to reduce the frequency and severity of such reactions.23,24 The question then is when and how to further reduce the number of contaminating leukocytes in PC24 Even with leukocyte reduction in blood components, all FNHTR may not be preventable. Patients with histories of FNHTR may benefit from premedication. As the debate on prestorage ULR continues and the cost of the leukocyte reduction filters decline, increased use of prestorage leukoreduced blood and blood components is likely to reduce the incidence of FNHTR.   Allergic Transfusion Reactions Acute reactions to plasma constituents may be classified as allergic, anaphylactoid or anaphylactic. Allergic reactions to an unknown component in donor blood are common, usually due to allergens in donor plasma or, less often, to antibodies from an allergic donor. IgE antibodies fix to mast cells and basophils, which cause the release of histamine and vasoactive amines.25 The reactions, are usually mild, with urticaria, edema, occasional dizziness, and headache during or immediately after the transfusion. Less frequently, dyspnea, wheezing, and incontinence may occur, indicating a generalized spasm of smooth muscle. Rarely, anaphylaxis may occur.26 In a patient with a history of allergies or an allergic transfusion reaction, antihistamine may be given prophylactically just before or at the beginning of the transfusion. Medications must never be mixed with the blood. If an allergic reaction occurs, the transfusion is stopped and an antihistamine is given to control mild cases, and transfusion may be resumed. For more severe reactions epinephrine should be given. A corticosteroid 26 In severe reactions washed or deglycerolized frozen red blood cells should be given.4

Anaphylactic transfusion Reaction Anaphylactic reactions are rare events, which are seen in patients who are IgA deficient and have developed anti-IgA antibodies. The IgA antibody production may follow immunization from previous transfusion or pregnancy and some patient may have the antibodies without any previous known exposure.4 IgA deficiency is the most common of all the selective deficiencies of serum immunoglobulins. IgA anaphylactic transfusion reactions are estimated to occur in 1 in 20,000 to 47,000 transfusions. The signs and symptoms of these reactions are dramatic and rapid in their onset and they appear suddenly after exposure to the IgA protein often before 10 mL of plasma have been infused. Symptoms may include nausea, abdominal cramps, emesis, and diarrhea. Transient hypertension may be followed by hypotension, shock and loss of consciousness. Absence of fever distinguishes an anaphylactic reaction from other immediate reactions. The diagnosis of

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