Temporary vascular access for extracorporeal renal replacement therapies in acute renal failure patients.

Temporary vascular access is an essential component to perform any extracorporeal renal replacement therapy (RRT) in the acute renal failure patient. RRT used in the acute setting may be categorized in two groups: intermittent (IRRT) and continuous (CRRT). Therapeutic indications are based on clinical and technical considerations. Continuous modalities are mainly utilized in intensive care units for hemodynamically compromised patient. Initially performed spontaneously via an arteriovenous circuit, CRRT modalities have progressively become venovenous with the circulatory assistance of a blood pump. Since both intermittent and continuous RRT modalities are now performed almost exclusively by venovenous modalities, this article deals exclusively with temporary venous catheters. At present, double-lumen catheters represent the most common vascular access for RRT modalities. Semi-rigid polyurethane catheters currently used in case of emergency are limited to short term use. Hemocompatible, flexible silicone catheters, less aggressive for the vessels, seem better suited for the medium and long term run. The tunneled silicone catheters (DualCath type) meet the short and long term needs, and allow for blood flow rates up to 400 ml/min. The internal jugular vein, particularly the right one, seems to warrant the proper functioning of catheters while reducing the risk of stenotic complications. Subclavian access should be limited in time and reserved for silicone catheters in order to limit the risk of stenosis and/or thrombosis. Femoral access, very useful in cases of emergency and respiratory problems, greatly impairs the patient's mobility and should be limited by time to prevent thrombosis and/or infection. Late and/or delayed dysfunctioning of catheters are indicative of a thrombosis. Performance standards of catheters are less of a limiting factor in continuous low flow RRT modalities than in the intermittent ones. Finally, careful handling of the catheter essential to prevent infectious complications.