The impact of apheresis platelet manipulation on corrected count increment.

BACKGROUND: Concentrating and washing apheresis platelets (APs) substantially reduce the number of allergic transfusion reactions likely due to removal of plasma. However, these processes may damage platelets (PLTs). This study evaluated whether concentrating or washing APs decrease the corrected count increment (CCI). STUDY DESIGN AND METHODS: This retrospective study evaluated individuals who initially received unmanipulated APs and subsequently received concentrated and/or washed APs at a large university hospital between 1998 and 2009. Concentrated units were prepared by reducing the plasma volume of APs by a goal of more than 67%. Washed units were prepared by washing the APs with 1 L of normal saline. The CCI (PLTs [×10(6)] × m(2)/L) for all transfusions was calculated. Hypothesis testing was performed with t tests for continuous variables and chi-square tests for dichotomous variables.
RESULTS: We evaluated 121 individuals: 46 patients who received unmanipulated, concentrated, and then washed APs; 59 patients who received unmanipulated and then concentrated APs; and 16 patients who received unmanipulated and then washed APs. Patient demographics were similar among the three groups. The mean CCI for unmanipulated AP transfusions at 0 to 2 hours posttransfusion was significantly higher than concentrated and washed PLT transfusions (p<0.001). When accounting for PLT loss due to manipulation, concentrating APs did not impact the CCI. However, the CCI remained significantly lower for washed products at all time points after transfusion (40.7% mean reduction at 20-24 hr, p<0.001).
CONCLUSIONS: Washing APs significantly reduces PLT count recovery and survival, as demonstrated by a significantly reduced CCI.