Haemostatic changes in plasma for transfusion during preparation and storage

Abstract: The haemostatic quality of plasma for transfusion is liable to be affected by techniques for preparation and storage. We have studied changes in the contact system, coagulation and fibrinolysis under the following conditions: blood drawn into a half-strength citrate anticoagulant solution, virus inactivation of plasma with methylene blue and red light, and plasma storage in the fluid phase. Blood is normally drawn into a citrate-phosphate-dextrose (CPD) anticoagulant solution. We evaluated the stability of factor VIII other coagulation factors and their inhibitors in blood drawn into half-strength citrate CPD (0.5CPD) and kept at room temperature for eight hours before component preparation., We found no activation of the contact system or coagulation, but a significantly increased stability of coagulation factors VIII and IX. During virus inactivation of single donor units of fresh plasma with methylene blue and red light, the concentration of clottable fibrinogen was unchanged but functional fibrinogen decreased in a light-dose dependent manner. Turbidity measurements of fibrin gel showed a lower fibrin fiber mass-to-length ratio after the treatment, indicating a tighter fibrin gel Structure. Normal clot stability and fibrinolysis were found. L-histidine added to plasma before the treatment normalized the prolonged thrombin-induced coagulation time in a dosedependent way. We defined cold activation of plasma as an elevated kallikrein-like activity. During storage of plasma from male donors at +4 ºC for 42 days, the cumulative frequency of cold activated plasma units increased in a time-dependent manner. When tested on two occasions, the majority of cold activators remained the same and so did the majority of non-cold activators. However, large intraindividual differences in the onset days of cold activation were observed in plasma of some of our male donors. Cold activation was associated with a high degree of activation of the contact system and coagulation. Minor changes in fibrinolysis were observed. We have developed a method, to be used before storage, for the selection of transfusion plasma units stable at +4 ºC for a certain period. In plasma units with short lag phase before cold activation, an imbalance was found between the functional levels of the contact proteins and their inhibitors on day 0, which suggests a mechanism leading to cold activation. An additional mechanism may be involved. In conclusion, we have found an increased stability of factors VIII and IX in 0.5CPD. We have demonstrated changes in fibrin polymerization and gel structure after the methylene blue and red light treatment, and an activation of the contact system and coagulation during plasma storage at +4 ºC For a uniform quality of transfusion plasma units, it is important to maintain normal functional levels of all haemostatic proteins, including zymogen forms of proteinases, cofactors and proteinase inhibitors. An exclusion of cold-activated plasma units would increase the stability of several haemostatic proteins during storage at +4 ºC.