Blood loss during repair of craniosynostosis

Editor—I write regarding two papers published some time ago, as an issue for clarification or correction. Both papers come from the same group in Paris and both use the same method for estimation of blood loss, detailed in the text and appendix of the two papers, respectively. 2 This method was based on and attributed to the method used by Kearney and colleagues. I believe there is an error in the method used by the Paris group in the calculation of estimated red cell deficit (ERCD). They state that ERCD=estimated red cell volume (ERCV)·packed cell volume (PCV) in Meyer and colleagues’ paper, and ERCD=ERCV· difference in haematocrit in Dahmani and colleagues’ paper. But, ERCD should be calculated as estimated blood volume (EBV; not red cell volume)·difference in haematocrit. This method has been used in a number of other studies that have taken ERCD= EBV·difference in haematocrit.