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Background and Objectives Materials and Methods Results Conclusion Quantifying the contribution of individual coagulation factors to haemostasis may aid our understanding of the haemostatic function in patients with rare coagulation deficiencies (RCDs) and the exploration of suitable treatments.Reconstituted blood prepared from specific coagulation factor‐deficient plasma (factor [F]II; prothrombin, FV, FVII, FVIII, FIX, FX, FXI or FXII) and red blood cell/platelet products were used to simulate the whole blood of patients with RCD. We prepared in vitro treatment models for patients with prothrombin deficiency using coagulation factor agents and fresh frozen plasma. Haemostatic function was measured using a microchip flow chamber system at 600 s−1.The haemostatic function was low, especially in blood samples reconstituted with prothrombin‐ and FX‐deficient plasma. In a plasma transfusion model of prothrombin deficiency, haemostatic function recovered after 10% replacement with normal plasma and reached a plateau at ≧60% replacement. A treatment model of prothrombin deficiency with prothrombin complex concentrates revealed dose‐dependent therapeutic effects in the range of 0–50 IU/kg.Microchip flow chamber system‐based quantification of haemostatic function using reconstituted blood could predict haemostasis and therapeutic effects of treatments in patients with prothrombin deficiency. [ABSTRACT FROM AUTHOR]

Background and Objectives Materials and Methods Results Conclusion The total thrombus‐formation analysis system (T‐TAS) can quantitatively analyse the contribution of platelets to haemostasis using reconstituted blood samples. However, it is unsuitable in cases with low platelet counts. We introduced a haemodilution (HD) chip with a shallow chamber depth, adapted to low platelet counts and high shear conditions (1500 s−1).Blood samples were prepared by mixing red blood cell products, standard human plasma and platelet products; the final platelet count was 50 × 103/μL. Aggregation tests were performed by using the aggregation inducers collagen, adenosine diphosphate (ADP) and ristocetin. Samples with 2‐, 4‐ and 9‐day‐old platelet products (N = 10) were evaluated.The HD chip enabled the stable analysis of the haemostatic function of all samples at a platelet count of 50 × 103/μL. Haemostatic function was correlated with ADP aggregation (time to 10 kPa [T10]: r = −0.53; area under the curve for 30 min: r = 0.40) and storage period (T10: r = 0.44).The HD chip‐mounted T‐TAS can stably analyse haemostatic function under low platelet counts and high shear conditions; this approach is expected to serve as a bridge to in vivo haemostatic tests with experimental animals. [ABSTRACT FROM AUTHOR]