Microaggregate blood filtration and the febrile transfusion reaction. A comparative study

Seventy-four patients with chronic transfusion requirements and histories of repetitive febrile reactions were transfused with 1138 units of microaggregate-filtered red cells. The filtered blood was prepared using either a direct interception or a depth filter. One-half of the units were centrifuged immediately prior to filtration. Microaggregate filtration reduced the overall incidence of febrile transfusion reactions by 77 percent. The centrifugation-filtration protocol reduced the rate of reactions by 98 percent. There were no differences between the ability of the different filters to reduce the reaction rate; however, red cell loss was twice as large with the depth filter as with the direct interception filter. The numerical criterion for "leukocyte-poor blood" was met in all units processed by centrifugation-filtration. Only units processed during the last 2 weeks of shelf-life fulfilled this criterion when centrifugation was omitted from the procedure. The majority of the latter units were clinically tolerated well due to their reduced granulocyte content.