Development of a new approach to vascular access

Three modes of access for hemodialysis (HD) have been available for over 20 years, the native arterial to venous (A-V) fistula, the polytetrafluorethylene (PTFE) graft fistula, and the central venous catheter. Overall, vascular access remains the single most costly source of morbidity and hospitalization in HD patients, indicating a severe need for improvement in this area. A significant contributor to access morbidity is the HD catheter, which protrudes through the skin and is subject to frequent infection. Subcutaneous ports have been developed to overcome this problem with catheters, but their application to HD has been elusive for 2 reasons, the use of a degradable septum that becomes vulnerable to infection with the use of large bore needles and the presence of a nonlinear flow path which produces damage to blood cells and stimulates thrombus formation at the required high flow rates. A new device, the Dialock, overcomes these objections by its use of a mechanical valve that maintains a linear flow path without directly contacting the blood. Results of a pilot study with 23 patients demonstrated a 78% cumulative survival rate after 1 year with a reduced rate of infection compared to catheters and sustained blood flow of 330 ml/min. The device represents a most promising advance in vascular access.