In vitro blood compatibility of glow discharge‐grafted silicone rubber tubings

Small diameter silicone rubber tubings were grafted with vinyl methyl acetamide using a glow discharge treatment. Discharge conditions were chosen which allowed grafting exclusively on the inner surface of the tubings. Increasing the voltage as well as a posttreatment at increased monomer vapor pressures leads to higher conversions as a posttreatment at increased monomer vapor pressures leads to higher conversions as determined by contact angle measurement and gravimetry; no influence of the discharge pressure could be observed. Human blood plasma exposed to the grafted tubings showed some alterations in comparison to blood plasma exposed to ungrafted tubings. A prolongation of the activated partial thromboplastin time and lower levels of factor V and platelet factor 4 were measured, while almost no differences in the generation of fibrinopeptide A could be noticed. Platelet adhesion on grafted tubings was less than on unmodified tubings.