The hemostatic system in children undergoing intensive plasma exchange.

We report the effects on the hemostatic system of intensive plasma exchange therapy using replacement fluids devoid of plasma coagulation proteins. Five children were studied during ten exchanges. There were no hemorrhagic episodes clearly attributable to the plasma exchange, but one patient developed recurrent thrombosis of the vascular access used for the procedure. Plasma values of the various coagulation factors (II to XII) were decreased by 35 to 67% immediately following the plasmapheresis. The mean decrease in levels of antithrombin III antigen and activity and of plasminogen were 58, 60, and 66%, respectively. The recurrent thrombosis of the vascular access in one of the patients, and the decrease in antithrombin III and plasminogen values in plasma following plasmapheresis in all patients, suggest that there is increased potential for thrombosis in patients undergoing intensive plasmapheresis, despite the depletion of coagulation factors. At 24 hours following plasmapheresis the values for all factors were within normal limits, attesting to the ability of the synthetic mechanisms in children to replenish hemostatic factors rapidly.