Non-infectious complications of transfusion therapy

Blood transfusion is considered safe when the infused blood is tested using state of the art viral assays developed over the past several decades. Onl y rarely are known viruses like HIV and hepatitis C transmitted by transfus ion when blood donors are screened using these sensitive laboratory tests. However, there are a variety of transfusion risks which still remain that c annot be entirely eliminated, many of which are non-infectious in nature. P redominantly immune-mediated complications include the rapid intravascular or slow extravascular destruction (hemolysis) of transfused red cells or ex travascular removal of platelets by pre-formed antibodies carried by the tr ansfusion recipient. Alternatively, red cells can be damaged when exposed t o excessive heat or incompatible intravenous fluids before or during the tr ansfusion. Common complications of blood transfusion that at least partly i nvolve the immune system include febrile non-hemolytic and allergic reactio ns. While these are usually not life-threatening, they can hamper efforts t o transfuse a patient. Other complications include circulatory overload, hy pothermia and metabolic disturbances. Profound hypotensive episodes have be en described in patients on angiotensin-converting enzyme (ACE) inhibitors who receive platelet transfusions through bedside leukoreduction filters. T hese curious reactions appear to involve dysmetabolism of the vasoactive su bstance bradykinin. Products contaminated by bacteria during blood collecti on and transfused can cause life-threatening septic reactions. A long-term complication of blood transfusion therapy unique to chronically transfused patients is iron overload. Less common - but serious - reactions more speci fic to blood transfusion include transfusion-associated graft-versus-host d isease and transfusion-associated acute lung injury, Many of these complica tions of transfusion therapy can be prevented by adhering to well-establish ed practice guidelines. In addition, individuals who administer blood trans fusions should recognize these complications in order to be able to quickly provide appropriate treatment. (C) 2001 Harcourt Publishers Ltd.