EVALUATION OF PLATELET-FUNCTION USING THE IN-VITRO BLEEDING-TIME AND CORRECTED COUNT INCREMENT OF TRANSFUSED PLATELETS

The functional capacity of transfused platelets was evaluated with in vitro bleeding time (IVBT) and corrected count inclement (CCI) in orde r to compare platelet concentrates (PCs) derived from pooled buffy coa ts (BC-PCs) with PCs collected by apheresis (A-PCs). The suspension me dium in the BC-PCs was 30% CPD plasma and 70% of an additive solution (containing sodium and potassium chloride, sodium citrate and phosphat e, mannitol), and in the A-PCs the medium was 100% CPD plasma. IVBT wa s evaluated using a Thrombostat 4000/2. BC-PC and A-PC were transfused 57 and 41 times, respectively to 36 patients with chemotherapy-induce d thrombocytopenia. PCs transfused within 2 days of donation were cons idered fresh, and those transfused within 3-5 days were considered sto red. IVBT was determined before, as well as 10-30 min and 24 h after t ransfusion; CCI was determined 10-30 min and 24 h after transfusion. T he median pretransfusion IVBT value was 486 s. It was measurable in 21 of 98 (21%) of the transfusions, i.e. below the cutoff limit of 486 s . Ten to 30 min after transfusion, the IVBT showed a measurable reduct ion in 90% of the transfusions with fresh BC-PCs, 92% of those with fr esh A-PCs, 63% of those with stored BC-PCs and 79% of those with store d A-PCs. After 24 h, the corresponding values were 63% for fresh BC-PC s, 50% for fresh A-PCs, 26% for stored BC-PCs and 38% for stored A-PCs . The median value of CCI 10-30 min after transfusion was 20 for fresh BC-PCs, 17 for fresh A-PCs, 16 for stored BC-PCs and 14 for stored A- PCs. The difference in IVBT between fresh and stored BC-PCs was signif icant (p = 0.032), unlike that between fresh and stored A-PC. After 24 h the corresponding values were 7 for fresh BC-PCs, 4 for fresh A-PCs , 4 for stored BC-PCs and 3 for stored A-PCs. When all transfusions wi th fresh PCs (BC-PCs+A-PCs) were compared with all transfusions with s tored PCs, a statistical difference was demonstrated in both CCI (p = 0.027) and IVBT (p = 0.043). Spearman's rank correlation coefficient ( r(s)) was -0.41 between CCI and IVBT486 s 10-30 min after transfusion, and -0.55 between the post-transfusion plateled count and IVBT, indic ating a relatively poor correlation between CCI and IVBT, and a slight ly better correlation between platelet count and IVBT. In conclusion, BC-PCs showed a slightly higher CCI and a better response in IVBT than A-PCs. No statistical difference was demonstrated between BC-PCs and A-PCs transfused within 2 days after donation, with respect to functio n and recovery in vivo. BC-PCs stored for 3 days or more showed about the same CCI and IVBT as stored A-PC but significantly lower CCI and h igher IVBT than fresh BC-PCs. This may indicate that the preparation a nd/or storage conditions were not optimal. IVBT seems to be a useful p ossibility to test the in vivo behavior of transfused platelets.