[Changes in blood rheology and microcirculation after preparatory combined thrombocytapheresis and plasmapheresis]

Because of anticoagulation, changes in blood composition, and--perhaps--extracorporeal circulation, donor apheresis should cause alterations in hemorheology and hence in the perfusion of the microvasculature.

19 regular blood donors were included. According to our standard protocol for automated collection of blood components with the MCS 3p cell separator, we harvested 1 unit of platelets and 2 units of plasma in each case. Prior to, 1 h after, and 24 h after donation, the following parameters were measured: total serum protein (tsp), hematocrit (hc), whole blood and plasma viscosity (wbv/pv), red cell aggregability (rca) and blood flow velocity of the nail-fold capillaries (bfv).

The following parameters decreased 1 h/24 h after donation: tsp (p < 0.001/p = 0.008), elastic wbv (p = 0.018/p < 0.001), viscous wbv (p = 0.85/p = 0.0031), pv (p < 0.001/p < 0.001), static rca (p < 0.001/p = 0.0073), dynamic rca (p < 0.001/p = 0.017). The hc showed an initial increase (p < 0.001) with a subsequent overshooting decrease after 24 h (p < 0.001). 1 h after donation bfv raised (p = 0.0065). It decreased after 24 h and remained only slightly higher than the initial level (p = 0.27).

Automated combined collection of platelets and plasma gives rise to: i) Improvement of rheological properties of the donor's blood and increased bfv of his nail-fold capillaries within the 1st h after apheresis. ii) 24 h after donation the improved hemorheological properties remain demonstrable, but the bfv of nail-fold capillaries declines and shows a trend toward the starting-point. iii) Taken together, this is possibly reflecting adapted hemodynamic and vasoconstrictor regulation for altered hemorheological conditions.