QUALITY-CONTROL OF PLATELET CONCENTRATES - FUNCTIONAL ASSESSMENT OF PLATELETS STORED IN-VITRO

Platelet concentrates transfused for correction of thrombocytopenia or reduced platelet function do not consistently improve primary haemost asis in the recipient. Insufficient therapeutic effects may be caused by impaired donor platelet function and by unfavourable donation and s torage conditions, as well as by immunological interactions with the r ecipient blood. The present study was designed to investigate whether the effect of platelet transfusion on recipient platelet function can be predicted by in vitro methods. Methods. Blood samples were taken fr om 12 thrombocytopenic patients before (20 ml, P-o) and after (10 ml, P-vivo) transfusion of one unit of platelets previously stored for 24- 120 h in acid citrate dextrose. An additional sample was taken from th e platelet concentrate (TK) immediately before transfusion. P-o was di vided into two specimens and TK platelets were added to one of them (P -vitro) in order to obtain a platelet count similar to that in P-vivo. Bleeding time (BT) and bleeding volume (BV) of the samples P-o, P-viv o and P-vitro were measured using the method of Kratzer and Born (Fig. 2) [17]; mean values were calculated for each sample from six measure ments. Aggregability of TK platelets was determined in addition by agg regometry [2]. In contrast to previous studies, physiological Ca2+ con centrations were restored and secondary haemostasis was inhibited by l ow-molecular-weight heparin (Fragmin P, Pfrimmer Kabi GmbH und Co. KG, Erlangen) in the platelet-rich plasma used for aggregometry. Results. Platelet counts increased in all patients after transfusion (P-vivo V S P-o, Table 1) and were nearly identical in P-vitro and P-vivo (r=0.9 4, P < 0.001; Fig. 3). Parameters of primary haemostasis were signific antly improved by addition of platelets to P-o in vitro (BT P < 0.05, BV P < 0.01) as well as by platelet transfusion (BT P < 0.05, BV P < 0 .01). Direct comparison of P-vitro and P-vivo yielded a very close cor relation of BT r=0.88, P < 0.001) and BV (r=0.89, P < 0.01) in both sa mples. Although aggregometry revealed decreasing platelet function wit h increased storage time, aggregability was considerably higher compar ed to previous studies of platelet concentrates stored for 2-5 days. C onclusion. A new technique has been developed which allows reliable pr ediction of the effect of platelet concentrates on primary haemostasis of the recipient by in vitro measurement of bleeding time and bleedin g volume prior to transfusion using the method of Kratzer and Born.