Major ABO incompatible BMT in children: determining what residual volume of donor red cells can safely be infused following red cell depletion.

Major ABO incompatible BM transplantation carries a risk of acute haemolysis. Red cell depletion reduces this risk but not all incompatible RBC (iRBCs) are removed and in children the residual volume can be significant relative to body weight. We sought to determine the volume of iRBCs that can be safely given to children. All patients receiving fresh BM from a donor with a major ABO blood group mismatch between January 2000 and July 2013 at the Hospital for Sick Children, Toronto, were included. Seventy-eight patients were identified. The median volume of iRBCs transfused was 1.6 mL/kg (range 0.1-10.6 mL/kg). Thirty-five patients had minor haemolytic events and five patients had clinically significant adverse events. Two patients, who received 3.66 and 3.9 mL iRBCs/kg, developed renal impairment and in one case hypoxia and hyperbilirubinaemia. One patient had mild hypotension that resolved with i.v. fluid. Two patients developed hypotension secondary to sepsis and unrelated to BM infusion. Although signs of haemolysis occur, with appropriate hydration and monitoring of renal function, clinically significant adverse events related to the infusion of ABO incompatible BM are rare, and, in this study, were only seen in patients receiving >3 mL/kg of iRBCs per kg.