Reducing the Morbidity of Tunneled Hemodialysis Catheters—A Symposium

Abstract

Tunneled dialysis catheters (TDC) are and will, for the foreseeable future, continue to be the proverbial thorn in the side of nephrologists and their dialysis patients. With the goal of lessening the prick of this thorn, I have chosen eight topics and highly qualified authors to share their TDC expertise with this journal’s readers. Over 70% of incident and 21% of prevalent chronic hemodialysis patients in the United States use a TDC to receive dialysis therapy, rates that have increased in recent years. While the “Fistula First Initiative” has, by implication, been blamed for this unfortunate trend, a close examination of the issues shows that the initiative has not caused an increase in the prevalence of catheters. Several issues continue to surround the use of TDCs. For instance, in addition to causing central venous stenosis, multiple reports have demonstrated that TDCs have a risk of infection-related and all-cause mortality higher than those seen with arteriovenous fistulae or synthetic grafts. For these and other reasons, the National Kidney Foundation’s Kidney Disease Outcome Quality Initiative (NKF-KDOQI) Clinical Practice Guidelines for Vascular Access recommends that less than 10% of prevalent chronic dialysis patients be treated using a TDC. Catheter-related bacteremia is a major cause of morbidity and mortality among catheter-dependent hemodialysis patients. Diagnosis relies upon clinical features and positive blood cultures. Administration of antibiotics, catheter exchange, formation of a new tunnel, and removal are some of the management strategies with a varying degree of success rate. Indeed, TDC-related bacteremia is the most serious type of infection which can result in septic arthritis, endocarditis, discitis, paraspinal abscess, and even death. Prophylaxis of catheter-related bacteremia then becomes an important element to lower infection rates. Recent data have emphasized a variety of antibiotic and antimicrobial agents that are effective in the form of “lock solutions” in reducing the risk of catheter-related bacteremia. Nevertheless, at present none of these agents are approved by FDA for this use. Biofilm, fibro-epithelial sheath and thrombus formation are other important problems that lead to infection and catheter dysfunction. The NKF-KDOQI defines catheter dysfunction as failure to attain a sufficient extracorporeal blood flow of ≥300 ml/minute with a prepump arterial pressure exceeding negative 250 mmHg. In simple terms, decreased blood flow rates, frequent arterial, and venous pressure alarms resulting in poor clearance are termed as catheter dysfunction. While thrombolytic therapy, catheter exchange, and obliteration of the fibro-epithelial sheath have been used in the management of catheter dysfunction, antimicrobial and antithrombotic coatings for catheters are in development to combat these issues. Since the introduction of TDCs, numerous designs have emerged, each with advantages and disadvantages. A catheter that self-centers in the superior vena cava has recently been developed; it prevents contact of the catheter tip with the wall of the vessel and provides optimal blood flow irrespective of its tip’s position in the superior vena cava. Advances in technology are focusing on the development of biocompatible catheters that will provide adequate blood flow rates at normal arterial and venous pressure, resistance to occlusion by fibrous sheathing, prevention of infection, and avoidance of clotting. I hope that this symposium is successful in providing nephrologists with up to date information on tunneled hemodialysis catheters. I further hope that we (the authors and I) can play a small role in improving the care of our dialysis patients who depend upon catheters to survive.