In vitro hemostatic properties of French lyophilized plasma.

French lyophilized plasma (FLyP) is used routinely by the French Armed Forces in war settings. The authors compared concentrations of coagulation proteins and global in vitro hemostatic properties in FLyP and in the same plasma before lyophilization to assess the impact of lyophilization on coagulation properties. Twenty-four batches of plasma before and after lyophilization were tested for coagulation proteins. Thrombin generation time, thrombin antithrombin concentration, prothrombin fragment 1 + 2, and thromboelastography were assessed. Finally, the efficiencies of FLyP and plasma before lyophilization were compared on a hemorrhagic shock hemodilution model and tested on TEG(Haemoscope Corporation, Glenview, IL). Prothrombin time ratio (1.1 ± 0.1 vs. 1.2 ± 0.1) and activated partial thromboplastin time (35 ± 1.3 vs. 39 ± 2.4 s) were significantly increased in FLyP (8 ± 3%, P < 0.05 and 11 ± 5%, P < 0.001, respectively). Activity of factors V (85 ± 18 vs. 51 ± 16 UI/ml) and VIII (0.77 ± 0.11 vs. 0.62 ± 0.10 UI/ml) was also diminished (25 ± 12% and 20 ± 7%, respectively); however, activity of other factors was preserved. The authors observed no alteration in the thromboelastographic parameters. Thrombin generation was preserved when induced with 5 pM tissue factor in vitro but significantly reduced when using 1 pM tissue factor. The thrombin-antithrombin complex and prothrombin fragment 1 + 2 attested for the absence of coagulation activation. This hemodilution model showed no significant difference before and after lyophilization. The study results account for a significant decrease of factors V and VIII in FLyP. However, the global capacity to induce clot formation in vitro seems to be preserved. The clinical relevance of these decreased factors is not known.