Acute renal failure is associated with increased mortality in the Pediatric Intensive Care Unit. When anuric or oliguric renal failure occurs, the associated fluid overload may compromise respiratory function and has been shown to be associated with worse outcomes. Renal replacement therapy using continuous venous-venous hemofiltration (CVVH) allows for fluid, solute, and nitrogenous waste removal. However, large bore vascular access with placement of a double-lumen dialysis catheter is necessary to ensure effective flow rates to allow for CVVH. We present a technique to facilitate exchange of a 4 Fr double-lumen central venous catheter to an 8 Fr double-lumen dialysis catheter for CVVH in a 2-year-old toddler who developed acute renal failure following surgery for congenital heart disease. This technique may be particularly valuable in patients with associated conditions including fluid overload and coagulation disturbances which may increase the morbidity of vascular access techniques.