The influence of freezing methodology on coagulation factor preservation in fresh frozen plasma: A pilot study

Rapid freezing is thought to better preserve labile coagulation factors in fresh frozen plasma (FFP). This pilot study compared contact shock freezing (CSF) with conventional freezing (CF) to assess their effectiveness in maintaining post-thaw coagulation factor levels. Although the ABO blood group may influence plasma characteristics, its role was not a primary objective and was only noted for preliminary observation during the comparison of the two freezing methods.

In a prospective pilot study, plasma from 75 donors (balanced by ABO group) was divided into matched aliquots and subjected to either CSF (30min at -30°C) or CF (7-8hours at -30°C). Post-thaw analyses of PT, aPTT, fibrinogen, factor V, factor VIII, and factor IX were performed. Non-parametric statistics (Wilcoxon Signed-Rank tests and Aligned Ranks Transform ANOVA) were used for analysis.

Study data suggested a trend towards superior preservation with CSF, yielding lower median PT and aPTT and higher median activities of fibrinogen, factor V, and factor VIII. Notably, statistically significant interaction effects between the freezing method and ABO group were observed for fibrinogen (P=0.033), factor VIII (P=0.012), and factor IX (P=0.003). Post-hoc analysis indicated that the potential benefit of CSF for fibrinogen may be most pronounced in group AB, and for factor VIII in group B, while CF might better preserve factor IX in group A.

This in vitro pilot study demonstrates that contact shock freezing is superior to conventional freezing in preserving the coagulation integrity of fresh frozen plasma across all major parameters. The observed ABO-related differences emerged as incidental exploratory findings and should be interpreted with caution. The clinical significance of these biochemical improvements requires further investigation in well-designed clinical outcome studies.