Microaggregate formation in stored human packed cells: comparison with formation in stored whole blood and a method for their removal.

Experiments were performed to compare the formation of microaggregates in stored human whole blood (WB) with that in stored packed cells (PC) and also to compare the effectiveness of standard blood transfusion filters with dacron wool (Swank) micropore transfusion filters in removing such microaggregates. After 5, 10, 15 and 20 days of storage SFP and debris weights of PC's were considerably greater than those of matched WB samples. Passage of either WB or PC's through standard blood transfusion filters resulted in small decreases in SFP and debris weights. Passage of either WB or PC's through dacron wool (Swank) transfusion filters led to striking and highly significant decreases in both SFP and debris weights. When stored PC's were diluted to the same hematocrits as their corresponding WB samples, SFP remained considerably elevated above those of the WB samples. On the basis of this research, it is concluded that centrifugation of blood during component separation leads to a significant increase in microaggregate formation over and above that which progressively occurs during storage and that the risk of pulmonary microembolization during transfusion with stored PC's is greater than that during WB transfusion. For this reason, dacron wool (Swank) filters should always be used when PC's are being transfused.