In vivo and in vitro characteristics of double units of RBCs collected by apheresis with a single in‐line WBC‐reduction filter

BACKGROUND: A novel apheresis procedure for a blood separator (MCS+, Haemonetics) enables the collection of 2 WBC‐reduced RBC units in a single donation by using one disposable set with one in‐line WBC‐reduction filter (RC2H, Pall Corp.). The objective of this study was to evaluate the filtration performance in connection with different prefiltration RBC storage conditions and with the in vitro and in vivo storage quality of the filtered units. STUDY DESIGN AND METHODS: Sixty‐six 2‐unit RBC collection and gravity‐filtration procedures were completed at three sites, resulting in 132 RBC units. Filtration of the double RBC units was performed at room temperature (RT) within 8 hours of collection (n = 36) and under refrigeration (1‐6°C) for up to 24 hours (n = 10) and 72 hours (n = 20) before filtration. RBC quality was compared to that of nonfiltered apheresis RBC units (n = 10). RESULTS : Median filtration time was 6.5 and 14 minutes for units stored at RT and under refrigeration, respectively. All 132 RBC units had residual WBC counts <0.4 × 10 6 . The refrigerated units showed a greater mean log reduction in WBCs: 5.06 ± 0.16 (24 hour) and 4.74 ± 0.48 (72 hour), respectively, than did RT units: 4.47 ± 0.28 (p<0.05). RBC loss was less than 12 percent in all cases (mean, 7.8 ± 1.8%). Minimal differences in volume were observed between the paired RBC units. In vitro RBC storage characteristics of the filtered units were as expected and similar to those of the nonfiltered units. For RBC units held at RT (n = 24), the mean in vivo 24‐hour recovery was 81.8 ± 8.4 percent (double‐label). CONCLUSION: Satisfactory filter performance in terms of WBC removal and RBC loss was observed with all 66 procedures, irrespective of storage conditions before filtration.