Fresh blood units contain large potent platelets that improve hemostasis after open heart operations

Twenty units of fresh whole blood were separated into fresh packed red blood cells (PC) and platelet-rich plasma (PRP) and were transfused to 40 patients immediately after coronary bypass grafting. Patients were preoperatively randomized to receive either PRP (group A, 20 patients) or PC (group B, 20 patients). Platelet number in the PRP group was greater, but not significantly greater, than in the PC group (7.5 ± 3 versus 5.9 ± 2.2 × 10¹⁰; p = not significant). However, mean platelet volume in the PC group was significantly greater (8.75 ± 1.1 versus 6 ± 0.7 fL). Postoperatively, group A patients bled more than group B (566 ± 164 versus 327 ± 41 mL; p < 0.01) and received more red blood cell units (2.7 ± 1.2 versus 1.6 ± 0.7 U; p < 0.05) and a larger number of blood products (5.9 ± 3.7 versus 2.6 ± 1.2 U; p < 0.05). Transfusion of PRP to group A increased platelet count from 128 ± 20 to 148 ± 110 × 10⁹/L; however, platelet functions did not improve. Administration of PC to group B increased platelet count from 139 ± 22 to 156 ± 23 × 10⁹/L, improved platelet aggregation (with collagen from 33% ± 20% to 53% ± 23%, with epinephrine from 36% ± 24% to 51% ± 20%; p < 0.05), and corrected the prolonged bleeding time. The results suggest that the improved hemostasis observed after fresh whole blood administration is related to the large, potent platelets that remained in the PC and were not separated to the PRP during standard platelet concentrate preparation.