Platelet behavior in extracorporeal circulation (ECC).

Compatibility of blood with nonphysiologic materials is of increasing importance. The basis of estimating such compatibility has shifted from the determination of hemolysis to the estimation of the clotting capacity. This can be specified in terms of number and function of curculating thrombocytes and the resulting bleeding time. In this study components of commonly used standard equipment for open heart surgery have been compared to alternatives. The parameters studied yeild more relevant information for ranking materials in relation to their blood compatibility than does estimation of hemolysis alone. The behavior of the thrombocytes showed an initial dip (acute aggregation phenomenon), a plateau (equilibrium between aggregation and desaggregation) and a secondary dip (elimination of irreversibly damaged cells). Correlated to criteria of major hematological differences as observed between membrane-oxygenators and bubble-oxygenators, the percentage of circulating thrombocytes at the moment of the secondary dip gives the best overall information about hemocompatibility.