Extracorporeal blood volume of donors during automated intermittent-flow plasmapheresis and its relevance to the prevention of circulatory reactions.
BACKGROUND: Intermittent-flow plasmapheresis often involves a large extracorporeal blood volume of the donor during the procedure with the concomitant risk of circulatory reactions. Guidelines governing donor recruitment often apply an arbitrary threshold of 15 percent of the donors' blood volume not to be exceeded during hemapheresis procedures. No data demonstrating the suitability of this approach exist. STUDY DESIGN AND METHODS: The blood volumes of 1204 plasmapheresis donors were calculated with different formulae that utilized either body weight or body surface area. Extracorporeal blood volumes of these donors were determined for a commonly used intermittent-flow plasmapheresis machine known to result in a large extracorporeal blood volume. A validated model was employed that calculated the fluid volume shifts occurring during the procedure. The records of all plasmapheresis procedures of these donors were retrospectively reviewed for circulatory reactions. RESULTS: The median extracorporeal volumes ranged from 14 to 17 percent of the blood volume at a donor Hct level of 0.40 to 0.48 L per L for men and from 17 to 20 percent at a Hct level of 0.36 to 0.44 L per L for women. In more than 60 percent of male and more than 90 percent of female donors, extracorporeal volumes exceeded 15 percent of the blood volume during plasmapheresis. In this subgroup, 65 percent of male and 75 percent of female donors never presented with any signs of circulatory reactions. CONCLUSION: Application of an arbitrary threshold of 15 percent of the donors' blood volume not to be exceeded during hemapheresis procedures is expected to lead to an unjustified deferral rate in plasmapheresis donors.