PB1160 - Novel viscoelastic hemostatic assays demonstrate differences in the hemostatic properties of cold-stored and room temperature platelets in an in vitro transfusion model.

Background: Traditional viscoelastic hemostatic assays (VHA) report superior in vitro hemostatic properties of cold-stored platelets (CSP) when tested in the absence of red cells. However, the utility of novel VHAs to assess the viscoelastic properties of platelets stored under different conditions is unknown.

Aims: To assess the hemostatic properties of platelets stored under different conditions (temperature and duration) in an in vitro model of transfusion, using a novel VHA platform.

Methods: Double apheresis platelet donations (n=13) were split and stored at room temperature (RT: 20-24°C) or refrigerated (CSP: 2-6°C). Platelets were sampled at day 1 (before storage), 7, 14 and 21 and reconstituted with red cells from fresh red cell concentrates and thawed fresh frozen plasma (haematocrit 40%; platelet volume 20%) to model the transfusion of platelets. Coagulation was activated with kaolin and tested by TEG5000 (Haemonetics) and ClotPro (Haemoview Diagnostics).

Results: CT demonstrated faster clot initiation of CSP at 7 and 14 days, but only at 7 days according to R-time (Table 1). Overall, the correlation between R-time and CT was very strong (r=0.8258; p< 0.001).
TEG angle demonstrated superior clot kinetics of CSP at 14 days, but this difference was not statistically significant by ClotPro.
MA and MCF demonstrated better clot stability of RT platelets at 7 days (Table 1), and these parameters correlated strongly (r=0.9029; p< 0.001). No other differences in the haemostatic properties of CSP and RT platelets were observed at 14 and 21 days.

Conclusion(s): The hemostatic properties of CSP appeared similar to RT platelets during extended storage (beyond 7 days). However, the VHAs revealed different clot initiation and clot kinetics in CSP at 14 days storage. Correlation between expected VHA parameters was very strong. As such, this whole-blood transfusion model suggests that novel VHAs are suitable for the hemostatic assessment of platelets stored under different conditions.