I also work at a children's hospital and what we do for ECMO is upon the circuit start-up we provide leukoreduced packed cells that are 7 days or less( we term them as fresh). If we do not have fresh cells then we would wash. For booster transfusion there is no requirement. Our cardiac patient always received fresh red cells, so for them its either fresh or washed while on ECMO. We do have to types of ECMO VA and VV. VV they may request for wahed cells but they.