Summary
A direct relationship has been shown between platelet adhesion and critical surface tension of uncharged hydrophobic polymers when the air-blood interface is avoided. The similarity of this relationship to the previously observed relationship between critical surface tension and surface thrombogenicity suggests a possible major role for platelet activation as the initiating step in the surface-induced coagulation of blood on uncharged, hydrophobic polymers. The apparent damaging effects of a blood-air interface, as indicated by unusually heavy platelet adhesion suggests that such interfaces should be avoided in all blood/surface studies.