THROMBIN ACTIVITY ASSOCIATED WITH INDWELLING CENTRAL VENOUS CATHETERS

Thrombotic complications are frequent with indwelling central venous c atheters and result in catheter dysfunction, vascular obstruction and may also contribute to catheter-associated infections. The pathogenesi s of catheter thrombosis is not well characterized but may involve ves sel damage, local stasis and catheter-associated thrombin formation. W e have, therefore, measured the thrombin activity associated with cent ral venous catheters removed from patients and have also deter mined t he ability of hirudin to inactivate catheter-associated thrombin. We o btained 48 catheters from 46 patients and removed 1 cm portions for st udy. These were taken from the distal end, 5 cm proximal, and 15 cm pr oximal from the end. Following washing, thrombin activity was measured with a chromogenic assay. Thrombin was associated with 40 of 48 cathe ters and with 100 of 144 segments with a mean activity of 132 +/- 27 m u U/cm with a range of 0 to 2,160 mu U/cm. Incubation in hirudin reduc ed the activity from a mean of 122 +/- 33 mu U/cm to 18 +/- 6 mu U/cm (p < .001). Scanning electron microscopy of selected catheters showed that some had areas of fibrin deposition which was not apparent visual ly. The findings indicate that indwelling central venous catheters fre quently have associated thrombin activity which can be inhibited by a direct-acting thrombin inhibitor such as hirudin.