Thrombin generation and coagulation factor content of thawed plasma and platelet concentrates

Background We assessed the haemostatic capacity of thawed plasma produced after ambient storage of whole blood for 24 h ( RTFP 24), and the supernatant of buffy‐coat derived platelet concentrates ( PC ). Methods Platelet concentrates ( n  = 20) were tested on days 1, 5 and 7 of storage at 22°C and RTFP 24 ( n  = 10) immediately following thawing and after 4 and 6 days storage at 4°C. Coagulation factor activity, thrombin generation ± an activator of protein C ( PROTAC ) and rotational thromboelastometry ( ROTEM ) were assessed. Results In plasma and buffy‐coat derived PC , there was a < 10% loss of factors II , IX and FX , but much higher loss of factors FV , FVII and FVIII . In plasma, the total or peak amount of thrombin generated was unaffected by storage for 6 days, with or without Protac ® , but there was an increase in lag time and decreased rate of clot formation by ROTEM . In PC , but not plasma, there was a 16% increase in FXII activity and increase in resistance to activated protein C, co‐incidental to 30% loss of free protein S. Conclusions These data suggest thrombin generation is relatively unaltered when RTFP 24 is thawed and stored for 6 days, and that the supernatant of PC has significant haemostatic capacity.