First Hemodiafiltration in the United States

DaVita started using the Nephros hemodiafiltration system in a pilot program based in its Colorado Springs facility to learn how the system compares with traditional hemodialysis in patient care. Nephros gained approval from the FDA in 2012 for the hemodiafiltration system, which may enhance traditional hemodialysis by filtering out a range of different-sized contaminants.

This program is the first commercial use of hemodiafiltration in the United States. The method has been approved and used in European dialysis settings for several years. Whereas dialysis works on a diffusion principle (carrying small waste molecules through a filter as a result of a solvent gradient that depends on differences in concentration to remove waste from blood), hemodiafiltration provides an extra boost of cleansing because of convection—moving molecules through a fluid under pressure and forcing out the large waste molecules, which are too large to be removed through the traditional diffusion principle.

The Nephros OLpūr MD Mid-Dilution HDF Filter is used to gain urea clearance of postdilution hemodiafiltration. The system maintains a proper fluid balance for the patient while offering clearance of toxins in the middle-molecule range. For a schematic of the system, visit

According to a 2006 study published in Nature, patients receiving high-efficiency hemodiafiltration had a significantly lower risk of mortality (35 percent) than did those receiving low-flux hemodialysis (p = 0.01). The observational results suggested that some aspect of hemodiafiltration may improve patient survival independently of its higher dose of waste removal.

To date, the Nephros system is the only one approved in the United States; Fresenius has a hemodiafiltration system in use in Europe that has not yet been approved by the FDA.