Achieving an optimal red cell mass by transfusion: is it possible and does it matter clinically? : S. Kinmonda, Z. Haidera, B.M. Hollanda, T.L. Turnera, J.G. Jonesc, H. Phillipsb and C.A.J. Wardropb, aPaediatric Department, The Queen Mother's Hospital, Glasgow, bDepartment of Haematology, University of Wales College of Medicine, cDepartment of Biochemistry, University College, Cardiff