The Ito "Flow-Through" Centrifuge. A new device for long-term (24 hours) plasmapheresis without platelet deterioration.
An efficacious procedure for continuous plasmapheresis in long-term extracorporeal circulation has not yet been devleoped. This technique could be important in plasma exchange or cross-exchange and in artificial organ support if it could be accomplished safely using heparin as the anticoagulant. When sheep were connected to the Celltrifuge for 23 hours and administered 150 units/kg per hour heparin anticoagulant, we found gross platelet clumping in separated plasma and a 60 per cent fall in platelet count. When 120,000 units of heparin were directly injected into the centrifuge bowl at the onset of the centrifugation followed by hourly heparin administration at 500 units/kg, there was no platelet clumping but the platelet count fell to 52 per cent. Under identical conditions the Ito Flow-Through Centrifuge, a new continuous flow centrifuge with no rotating seals, was used. We found no platelet aggregates and no drop in platelet count, and there was a 100 per cent recovery of platelets in the separated plasma. Platelets sampled from arterial blood and separated plasma were found to have normal function in vitro, and responded 100 per cent to both collagen and ADP. These results indicate that the Ito Flow-Through Centrifuge can be used in plasmapheresis with heparin anticoagulation with no donor platelet loss and normal function in separated plasma.