Whole Blood Holding at 22 °C: Coagulation Factor V and VIII Activity and Plasma Factor Content per Unit

IntroductionPlatelet preparation by the platelet-rich plasma (PRP) method requires whole blood held at 20-24 °C, whereas units processed only for red cells and plasma are often refrigerated.We compared factor V and VIII activity and factor content per unit in fresh frozen plasma (FFP) from these two processing pathways. MethodsIn this single-center observational study, we analyzed 160 FFP units: 91 from whole blood held at 22 °C and used for PRP-platelet preparation and 69 from whole blood held at 4 °C without platelet preparation; all units were processed within 8 h of collection.Content per unit was calculated from activity and volume.Individual units were assessed against the Directorate General of Health Services (DGHS), India, specification, and each pathway against the Council of Europe and United Kingdom criteria. ResultsFactor V (107.4 ± 20.1 vs 110.6 ± 21.5 IU/dL; t(141.1)= -0.98,p = 0.33) and factor VIII activity (118.8 ± 32.8 vs 131.0 ± 46.1 IU/dL; t(117.1)= -1.87,p = 0.06; ABO-adjusted t(157) = -1.67,p = 0.10) did not differ significantly.Plasma volume was lower in the 22 °C arm (186 ± 8 vs 257 ± 32 mL), so factor VIII content was 35% lower (220 ± 61 vs 340 ± 141 IU per unit; t(87.3)= -6.62,p < 0.001); after adjustment for volume, the difference was not significant (t(157) = 0.85, p = 0.40).All units met the DGHS (≥70 IU per unit), Council of Europe and United Kingdom factor VIII specifications. ConclusionHolding whole blood at 22 °C for platelet preparation preserved factor V and VIII activity, but the smaller plasma volume reduced factor content per unit.Plasma should be dosed and issued by volume rather than by unit count.