Quality analysis of blood components obtained by automated buffy-coat layer removal with a top & bottom system (Optipress (R)II)

Abstract

BACKGROUND AND OBJECTIVE: There are Council of Europe recommendations for the quality of blood components. We analyzed the quality of blood components processed by a top & bottom system (Optipress((R)) II), the routine method used in our blood bank, to test whether the components reached the recommended quality. DESIGN AND METHODS: Blood was collected in triple CPD-SAGM bags (Optipac((R)) Baxter). Whole blood (WB) was centrifuged at 4,158 g for 14 min before separation by an automated top & bottom system (Optipress((R) )II). Platelet concentrate (PC) was prepared by pooling four isogroup buffy-coat (BC) units before low-speed centrifugation, and transferring the supernatant (4 BC-PC) to a 5-day storage bag (PL732, Baxter). An alternative approach involved PC preparation from a single BC unit by adding approximately 70 mL of plasma before centrifugation, followed by transfer of the platelet concentrate (1BC-PC) to a 300 mL Teruflex((R)) transfer bag. Both 4 BC-PC and 1 BC-PC were stored in a flat agitator at 22 degrees C for up to 5 days after collection. Cell counts were determined, along with hemoglobin and hematocrit in a Sysmex K-800 cell counter. The pH was determined on day 5 at 22 degrees C. Weights were measured and volumes were calculated based on specific gravity. Statistical analyses were carried out using the Kolmogorov-Smirnov test as a normality distribution test, the t-test for parametric values and Wilcoxon's test as a non-parametric test. Statistical significance between samples was considered to have been reached when p<0.05. RESULTS: The best parameters for configuring the system were: strength 25; BC volume 33-55; level of BC 5.5. Red blood cell (n = 1,434) volume was 279+/-20 mL, with 54.92+/-7.16 g of hemoglobin. More than 96% of units had fewer than 1.2x10(9) white blood cells. Fresh plasma volume (n = 803) averaged 279+/-19 mL, with a white blood cell contamination of fewer than 0.1x10(9)/L in all samples examined (n = 23). Platelet recovery in BC was 92+/-9% of platelets present in WB; the percentage of removed leukocytes was 74+/-10%, and between 13 and 15% of RBCs were lost in the BC (95% confidence interval). The BC volume (n = 1,037) fitted the target volume of 60 mL, except for some devices, when Optipress II((R)) lost the configuration for this parameter. Of 4 BC-PCs 80.3% yielded more than 0.6x10(11) platelets per unit, whereas this criterion was only met by 59.7% of 1 BC-PCs, and a greater proportion of 1 BC-PCs (58.8%) showed pH values within the range of 6.5-7.4 after 5 days of storage in comparison with 4 BC-PCs (44.25%). INTERPRETATION AND CONCLUSIONS: Optipress II((R)) provides standardized, leukocyte-poor blood components. Council of Europe requirements were met in a large percentage of red-cell concentrates, with less than 92 and 74% of the original platelets and leukocytes, respectively, and a small hemoglobin loss per unit. The system gave an optimal yield in terms of plasma volume. The top & bottom technique allowed us to reduce the number of blood units per platelet concentrate from 6 to 4 units, with similar platelet yields compared with traditional procedures. Nevertheless, the storage conditions must be improved to satisfy all Council of Europe requirements for platelet concentrates.