SURFACE PASSIVATION BY HUMAN ALBUMIN OF PLASMAPHERESIS CIRCUITS REDUCES PLATELET ACCUMULATION AND THROMBUS FORMATION - EXPERIMENTAL AND CLINICAL-STUDIES

The contact of flowing blood with an artificial surface leads to adsorption of plasma proteins, followed by platelet adhesion and aggregation and thrombus formation. This phenomenon is enhanced by turbulent flow at joints, bifurcations, and constrictions. In therapeutic plasmapheresis using an IBM blood cell separator, blockage of the extracorporeal circulation system by platelet‐fibrin thrombi imposed a halt in treatment for manual clearance of the circuit for 66 in 149 cases (44%). Thus it was decided to passivate the surface of the extracorporeal circuit by filling the tubing with 4% human serum albumin 15–20 min before the treatment session and then displacing the albumin solution with the patient's blood without creating an air–liquid interface. After introduction of this technique, a blockage was observed for only 11 in 239 cases (5%). In vitro measurements of platelet accumulation on the internal surface of the circulation system were carried out using washed human platelets labeled with 111In‐oxine in the presence of a 40% hematocrit. Preadsorption of the surface with albumin reduced platelet deposition to 4–5% that observed for an equivalent pretreatment with physiological saline. Copyright © 1990 John Wiley & Sons, Inc.