Enoxaparin inhibits fibrin sheath formation and decreases central venous catheter colonization following bacteremic challenge

Objective. Inhibition of fibrin sheath formation by enoxaparin decreases catheter colonization. Fibrin-binding radioactive tracer and catheter weights quantify fibrin reduction. Design: Controlled experimental study of central venous line colonization. Setting. Animal laboratory. Subjects: Adult male Sprague-Dawley rats. Interventions. Central venous lines were introduced into right external jugular veins of 254 animals in three groups: enoxaparin, Fibrimage, and catheter weight The enoxaparin group (n = 196) received daily enoxaparin injections (n = 97) or catheter implantation only (n = 99); 176 received tail vein injections of Staphylococcus epidermidis on postoperative day (POD) 10. Twenty rats received saline injections as a control. On POD 13, catheters were removed and incubated in broth at 37 degrees C for 48 hrs. Turbid samples were plated. In the Fibrimage group (n = 39), 20 rats receiving enoxaparin were compared with 19 controls without enoxaparin; all received S. epidermidis injections on POD 10. Fibrimage, fibrin-binding radiolabeled tracer, was given 1 hr before catheter removal. In the weight group (n = 19), six rats received enoxaparin; 13 did not. All received injections of S. epidermidis on POD 10. Measurements and Main Results. Positive plates underwent analytic profile index testing, ensuring correlation with inoculum. Results were compared using Fisher's exact or chi-square tests. Gamma counts were determined in the Fibrimage group. Catheter tip weights were recorded. Results from the Fibrimage and weight groups were compared using Student's t-test. The enoxaparin group had fewer catheters colonized (17 of 77) vs. no enoxaparin (42 of 99; p < .01). Pericatheter sheaths contained less fibrin compared with controls. Fibrimage group gamma counts were significantly by decreased for the enoxaparin subgroup (x = 2244 counts per minute) vs. controls (x = 3767 counts per minute; p < .0002). The weight of catheter tips treated with enoxaparin (x = 39 mg) vs. controls (x = 90 mg) was also significantly decreased (p < .0001). Conclusions. Enoxaparin decreases the amount of fibrin surrounding central venous catheters. The incidence of catheter colonization decreases when the amount of fibrin within the pericatheter sheath decreases.