Short-term deviations in temperature during storage of plasma at -40°C do not affect its quality

Little data are available on the suitability of frozen plasma for transfusion when stored outside its normal temperature, which is the focus of investigation in this study.

Plasma was pooled and split to create 10 identical units on each of 24 occasions (12 Group A and O). Plasma was frozen and stored at -40°C for 2 weeks and then one of each of the 10 identical units was subjected to one of the following deviations in storage temperature: -18°C for 1 week, 1 month, or 2 months; -10°C for 1 week, 1 month, or 2 months; 4°C for 4, 24, or 72 hours; or stored at -40°C (control) before returning all units to -40°C.

Factor VIII was only significantly reduced when plasma was stored at 4°C for 24 hours or more or -10°C for 1 week. For all other arms of the study, the majority of units of plasma (>75%) remained above 0.70 IU/mL and more than 95% were above the lower limit of normal (0.50 IU/mL). The prothrombin time ratio only increased after storage at -10°C for 1 month or more, and the activated partial thromboplastin time ratio after storage at 4°C for 24 hours. None of the deviations in storage resulted in a decrease in fibrinogen activity.

These data suggest that plasma that has been stored at -40°C and exposed to storage temperatures and times of up to 4 hours at 4°C, 1 week at -10°C or 2 months at -18°C meets EU guidelines and is suitable for transfusion.