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Adverse Outcomes in Blood and Blood Component Therapy - page 5 / 19

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indirect antiglobulin test (IAT), Pinkerton et al16 conducted a review of 8 years' experience with such a policy. In that period, 54,725 units of packed red cells or whole blood were transfused to 10,146 patients. They found 4 clinically overt DHTR and 18 clinically silent DSTR. In 3 of the 22 patients, the offending antibodies were detectable in the pretransfusion serum by an enzyme IAT, but none was detectable by routine saline IAT against either a three-cell screening panel or the transfused cells. Therefore the inclusion of saline IAT crossmatch would not have prevented the delayed reactions. They concluded that the use of a saline IAT crossmatch offers no significant advantage over the current policy of using only immediate-spin crossmatch for those patients whose pretransfusion serum gives negative results in a three-cell screen using a saline IAT.16 A measure to prevent DHTR occurrence is a thorough medical history which must include previous transfusions, pregnancy, transplant and transfusion reactions. A type and screen should be done on all patients who may need a transfusion and who have previously been transfused. Antigen negative units must be provided for patients in whom a clinical significant antibody was previously identified but which may no longer be demonstrable. Febrile Non-Hemolytic Transfusion Reactions Febrile non-hemolytic transfusion reactions (FNHTRs) are common side effects after the transfusion of blood and blood components. Most of the reactions are mild, but some may be life threatening because of the possibility of severe anaphylactic shock. It occurs in about 0.5% of non-leukocyte reduced blood and blood component transfusions and patients with a history of FNHTR have about 15% risk of experiencing this adverse event again. It occurs in approximately 3% to 7% of patients receiving red blood cell transfusions and in 20% to 30% of those receiving platelet concentrates (PCs). It is the most common type of transfusion reaction and it is precipitated by the presence of leukoagglutinins present in the recipient plasma. The alloimmunization is usually the result of exposure to antigens through previous transfusion, tissue transplant or pregnancy. The leukoagglutinins are directed against antigens on monocytes, granulocytes, and lymphocytes. The febrile reaction may develop following complement activation through the production of C5a components, which induce the production of IL-1 by macrophages and monocytes. The hypothalamus initiates the synthesis of prostaglandins, which trigger the pyogenic effects of the IL-1. Febrile non-hemolytic transfusion reaction usually produces a rise in body temperature of 1oC or more, in association with the transfusion of blood or blood components and with no other explanation for the spike in temperature. Thus to make a diagnosis of FNHTR, other causes for the signs and symptoms must be excluded. Symptoms exhibited by the patient include fever, and rarely hypotension may be present.2

In the past leukoagglutinins were of foremost relevance as factors in FNHTR, however, their impact has faded with the introduction of leukocyte reduction devices. Contaminating inflammatory cytokines in PCs, such as IL-1, IL-6, IL-8, or TNF- have been shown to be instrumental in precipitating these reactions. These cytokines can accumulate in high concentrations in stored PCs, and their levels depend on the presence of contaminating leukocytes. Prestoarage filtration of PCs can dramatically reduce the number of contaminating leukocytes and consequently the inflammatory cytokines. Transfusion reactions still occur after the transfusion of leukocyte -reduced PCs therefore there might still be other underlying pathomechanisms besides the presence of leukocyte -derived inflammatory cytokines, which might also be involved in FNHTRs.17 However, FNHTR has been identified as a pivotal reason for prestorage universal leukocyte reduction.18,19

In 1998, the Blood Product Advisory Committee to the FDA voted that the benefit-to-risk ratio associated with leukocyte reduction was sufficient to recommend universal leukocyte reduction (ULR). Universal leukocyte reduction was introduced in Canada in 1999, with one of its stated goals being the reduction of FNHTRs. The American Association of Blood Banks (AABB) recommends that a leukocyte-reduced unit of blood or blood component must contain WBC less than 5 x 106 leukocytes. Uhlmann el al19 conducted a retrospective analysis of reported reactions to RBC transfusions before (1999) and after (first 6 months of 2000) the implementation of prestorage ULR at their institution They found that out of the 36,303 allogeneic RBC transfusions that were administered in 1999, 85 reactions (0.23%) were reported. The reactions were classified as FNHTR in 43 cases, allergic in 13, delayed hemolytic in 19, and miscellaneous in 10. Out of the 31,543 non-leukocytes reduced RBC transfusions that were performed in 1999, 78 reactions (0.25%) were reported. The reactions were classified as

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