Blood usage in transfusion-dependent patients. A theoretical model.

A model for blood requirements of transfusion-dependent patients is presented to relate the transfusion interval in days (I), the percentage fall in hemoglobin (F), and the time in days after a transfusion during which no red cell loss occurs (S). The model applies to both normal blood (S = 0) and to young red cell (YRBC) transfusions, giving I = (S + 120)/(200/F - 1) The model predicts prolongation of transfusion interval by use of YRBCs, and is also of use in establishing whether excess red cell destruction or significant red cell production is present in a transfusion-dependent patient receiving either normal blood or YRBCs.