COMPOSITION AND FORMATION OF THE SLEEVE ENVELOPING A CENTRAL VENOUS CATHETER

Purpose: After catheterization, 42% to 100% of central venous catheter s are surrounded by a ''fibrin sleeve.'' This sleeve has been consider ed the cause of catheter-related infections, withdrawal occlusion, and pulmonary embolism. The reactions between the vein wall and the cathe ter were studied. Methods: A silicone catheter was placed in the anter ior caval vein of 123 rats. After in situ fixation at scheduled interv als, the pathologic changes were studied on semi-serial histologic sec tions by means of light microscopy, transmission electron microscopy, and scanning electron microscopy (SEM). In 36 rats, the catheter was w ithdrawn immediately; in 72 rats, it was left in situ up to 6 months; and in 15 rats, the study was performed up to 10 months after withdraw al of a catheter that had remained in situ for 6 months. Results: In t he group in which the catheter was withdrawn immediately, mural thromb i disappeared by day 7. In the group in which the catheter remained in situ, thrombi remained around the proximal portion of the catheter. T his pericatheter thrombosis (PCT) was invaded by migrating and prolife rating smooth muscle cells (SMCs), originating from an injured vein wa ll, and transformed from day 7 into a tissue composed predominantly of SMCs and collagen and covered by endothelial cells. Later, the number of cells decreased, and the relative amount of collagen increased. Up to 10 months after withdrawal of the catheter, the collapsed sleeve w as still present within the vein. Conclusion: The sleeve around a cent ral venous catheter is not a fibrin sleeve, but a stable cellular-coll agen tissue covered by endothelium. It is mainly formed by smooth musc le cells migrating from the injured vein wall into the early pericathe ter thrombus.