A critical review of platelet yield by Haemonetics 30 . Based on literature and own observations.

By means of a Haemonetics 30 cell separator platelets were collected for transfusion purposes from 18 different blood donors. A median yield of 5.7 times 1011 platelets was obtained. The yield of platelets was found to be linearly related to the donors' initial platelet counts. The procedures were standardized by using one size of bowl (225 ml), performing 10 cycles per procedure, and performing all cycles as uniformly as possible. The median time per procedure was 118 min. Mild donor reactions were seen in 8 donors (44%) consisting of circumoral tingling. The decrement in the donors' platelet counts was 86 times 109/1, 37% of the initial platelet counts. The choice of the bowl size of 225 ml is motivated. The absurdity of the expression of yield per h of processing, and of yield per 1 of blood processed is discussed. Furthermore, it is shown, that neither the fall in haematocrit nor the fall in the platelet count during the procedure are linear. The formulas commonly used for calculating the blood volume and platelet extraction efficiency, which are based on these assumptions, cannot therefore, in our opinion, be used.