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Abstract
Aim To study the variation in packed red cell transfusion requirements amongst children on a four weekly transfusion programme for transfusion dependent Beta-thalassaemia major. Comparing the accuracy of prediction of transfusion volumes using standard formulas.
Methods We conducted a retrospective study over 5 years for eleven thalassaemia patients on four weekly transfusions. In our unit individual transfusion volumes were empirically adjusted based on previous requirements for that individual. Providing the child had been well actual volumes transfused when the pre-transfusion haemoglobin and pre-transfusion haemoglobin of the following transfusion were between 95–100 g/l was deemed an appropriate volume and calculated as mls/kg. We compared these against volumes calculated from three formulas: 3 × body weight × desired raise in Haemoglobin g/dl (formula 1), 4 × body weight × desired raise in Haemoglobin g/dl (formula 2) and 3/haematocrit of transfused unit × body weight × desired raise in Haemoglobin g/dl (formula 3). Body weight was expressed in kilogram and a UK standard for average haematocrit of transfused packed cells of 0.6 was used.
Results 11 children had 96 transfusions which were appropriate; complete weight data were available for 85. There were 5 males and 6 females with an age range of 1–14 years. 4 weekly mean transfusion requirements for individual children ranged from 12.8ml/kg to 20.8ml/kg; average of 16.3ml/kg. The intra-individual standard deviation for transfusion requirements ranged from 0.6mls/kg to 1.78ml/kg with an average standard deviation 1.12ml/kg. There was a significant inter-individual variation in transfusion requirements (p < 0.001, ANOVA). There was a significant difference between transfusion requirements calculated by the formulas (p < 0.001) and the empirical transfusion regime except for formula 2 which yielded a result for transfusion volume not significantly different from the empirically determined volume (Table 1).
Transfusion requirements boxplot with median, interquartile range and outliers
Conclusions There is significant inter-individual variation in transfusion requirements in children with thalassaemia on regular transfusion programmes. The formula; 4 x body weight x desired raise in Haemoglobin in g/dl closely predicts the volume required but the predicted volumes may need modification based on previous transfusion requirements.