[Why are calculated "in-vitro" effects of preoperative haemodilution in variance with respective clinical findings? (author's transl)].

Whereas theoretical calculations on the effect of hemodilution show a low gain of erythrocytes, the blood saving effect under clinical conditions is considerably higher. Withdrawal of 1,975 ml blood for haemodilution and an intraoperative blood loss of 2,480 ml resulted in saving of 298 ml of red cells or 850 ml of whole blood (haematocrit 35%). This amount of blood saved seems not very much, but it made the transfusion of donor blood unnecessary in cases when otherwise 1--2 units of homologous blood would have been given. Withdrawal of autologous blood 8--10 days prior to an operation planned to be performed under haemodilution is possible, in our experience however, not practical in clinical routine, because of the considerable logistical problems involved.