Evaluation of platelet concentrates stored for 5 days with reduced plasma volume

Currently, platelet concentrates (PCs) are stored in a suspending plasma volume of 45 to 65 mL. Previous studies using second-generation containers indicated that PCs stored for 5 days at volumes less than 30 mL have reduced in vivo percentage recoveries as compared to PCs stored at volumes of 50 mL or more.

This study has evaluated the effect of PC plasma volume on the maintenance of in vivo and in vitro platelet properties following 5 days of storage, with the purpose of establishing the minimum plasma volume in the range of 30 to 50 mL. Twenty paired studies were performed in which identical populations of platelets from the same donor (obtained by double manual apheresis) were stored in a normal volume (55-60 mL, control) and reduced volume (30-50 mL, test) of plasma. Comparison of in vivo viability between test and control PCs was performed after random radiolabeling of 1 unit with 51Cr and of the other with 111In, with simultaneous transfusion and with calculation of percentage recovery and the area below the survival curve (integral) as measures of viability.

When test unit volumes were > or = 35 mL, essentially identical platelet survival curves and in vitro results were obtained for test and control. The integral and the percentage recovery for the test units were (mean, 95% confidence interval) 98.7 (96.3-101.0) and 99.0 percent (94.7-103.3) of those values in the control units, respectively. Test units with volume < or = 34 mL demonstrated reduced in vivo viability with integral and percentage recovery of 81.1 (68.9-93.3) and 80.4 (69.3-91.5), respectively, as compared to the control units. This loss was associated with increased metabolic activity (lactate production), which may suggest platelet activation due to the increased surface-to-PC volume ratio.

These results show that the storage volume of PCs may be reduced from 50 to 60 mL to 35 to 40 mL without any significant decrease in in vivo or in vitro platelet quality.