Thrombogenicity testing of central venous catheters in vitro.

To date there have been no standard methods for assessing the thrombogenicity of central venous catheters. A procedure for testing the thrombogenicity of intravenous lines such as the silver-impregnated catheter by continuous blood flow in vitro was therefore developed. For this test, fresh blood was drawn from healthy human donors and anti-coagulated with sodium citrate (1:9). All material tested (catheter tubes with and without silver manufactured in the same way, polyethylene tubes and tubes with potentially thrombogenic material) were perfused through their lumen with anticoagulated blood for up to 31 hours. Blood samples were collected at different times from the test system at sites before and after the perfusion of the test catheters. The hemoglobin concentration, erythrocyte, leukocyte and thrombocyte counts and markers for thrombin activation (thrombin-antithrombin III-complex, F1 + 2)-prothrombin fragments) and for hyperfibrinolysis (d-dimers) were determined. No thrombin activation or signs of hyperfibrinolysis were detected in any material tested. Polyethylene tubes were found to cause hemolysis, as shown by a decrease in hemoglobin content from 15 g% to 4.5 g%. Tecothane tubes with and without silver did not induce hemolysis.