Determination of bleeding risk in thrombocytopenic patients receiving platelet substitution

Abstract Platelet counts do not really indicate the bleeding risk of thrombocytopenic patients. The post-transfusion platelet increments do not necessarily demonstrate its therapeutic efficiency, therefore, a functional test for the evaluation of the primary hemostasis is desirable. Conventional tests show either too low a correlation or are not repeatedly applicable. The in vitro bleeding test (IVBT) proved to be a very sensitive and specific test in the detection of platelet disorders. Its standard technique does not give valid data in the platelet range of 0–50 × 10 9 /L which is the range of platelet counts in thrombocytopenic patients under chronic platelet replacement. Two so-called thrombocytopenia-adapted IVBT modifications have been evaluated by the clinical study reported here. Sixteen patients with bone marrow a-/hypoplasia have been investigated pre-and up to 5 days post-transfusion (253 samples). Both modifications improved the estimation of the actual bleeding risk and the therapeutic efficiency of platelet transfusions in thrombocytopenic patients. The IVBT modification using a smaller internal aperture of the filter (TP-adapted IVBT 120) proved clearly superior as it gave more stable values even with platelet counts of about 10,000/μL. Nevertheless, the study has not permit us so far, to determine the critical values of the IVBT defining the individual bleeding risk by thrombocytopenia with any exactitude. This should be possible by a more extensive clinical study. Finally, in order for routine use to be cost-effective the enormous expenditure has to be reduced by technical and filter improvements.