Dialysis Clinic: Dysfunction of New Catheters by Old Fibrin Sheaths

Abstract

One hundred consecutive patients with upper extremity prosthetic grafts referred for either an angioplasty or treatment of a thrombosed graft were included in the study. After the patient's treatment was concluded, the angiographic images that had been created during the case were evaluated to determine if an upper arm vein was evident that would be suitable for the construction of an arteriovenous fistula (AVF). Criteria used to determine suitability included vein size measured at the level of the elbow, feeding artery size at the level of the elbow, absence of stenosis within the vein, and continuity with downstream unobstructed veins. Thirty-eight percent of patients had an upper arm graft and 62% had a lower arm graft. Since it was not possible to adequately evaluate patients with an upper arm graft, these patients were not included in any further evaluations. A total of 46 patients (74%) with a forearm loop graft had one or both of the upper arm veins that appeared to be optimum for the creation of an AVF. If the percentage of graft patients with venous anatomy conducive to the creation of a fistula revealed in this study is representative, then the percentage of fistulas in use could be very quickly increased to more than 50% by simply seizing the opportunity. This effort directed toward prevalent patients could yield results much more rapidly than limiting one's focus to incident patients.

UNRESOLVED ISSUES IN DIALYSIS: Long‐Term Management of the Tunneled Venous Catheter

“…Between the proximal and distal ends of the sheath is a so‐called transitional zone consisting of a combination of fibrin and connective tissue. As the sheath extends distally, it eventually closes over the tip of the catheter, where it can disrupt catheter function, creating a flap valve effect that will allow injection but prevent withdrawal of fluids (22).…”

“…Different approaches have been recommended for fibrin sheaths, including lytic enzyme infusion, stripping, and catheter exchange (22). For example, a continuous infusion of urokinase (250,000 U) over 3 hours during dialysis might prove effective (28).…”

“…Use of recombinant tissue thromboplastin activator (r‐TPA) might be more efficacious than urokinase (29,30). Fibrin sheath stripping is falling out of favor among interventionalists, since it offers no advantage over catheter exchange and simply adds to the cost of treatment (22).…”

Difficult central venous access removal: case reports of the use of endovascular snare shearing of endothelialized tetherings

“…It is unknown if the type of catheter (silicone vs nonsilicone) as well as variation in biocompatibility profiles affects the characteristics of fibrin sheath formation. These sheaths rarely cause problems during catheter removal because the smooth surface of the catheter slips through the fibrin sheath upon withdrawal from the vein [3]. In our cases, the proximal portion of the catheter was lodged within the fibrin sheath, preventing removal of the entire catheter.…”

Interventional Nephrology

“…Despite this, there is considerable dependence on central venous catheters (CVCs)-not just for bridge therapy, as was originally intended, but also for long-term access (1). Unfortunately, CVC use is associated with a high rate of infection (5), thrombus-related dysfunction (6,7), and the potential for central venous stenosis (8).…”