The regenerative dialysis (REDY) sorbent system

Abstract

SUMMARY: The concept of regenerating the spent hemodialysate instead of discarding it was first suggested by A. Johnson in 1966. Drs M. Maxwell and A. Gordon felt that development of the concept could provide information on uremic toxins and lead to a wearable artificial kidney. Suitable sorbents consisting of zirconium phosphate, hydrated zirconium oxide and carbon combined with urease were placed in a cartridge by Dr. L. Marantz. Uremic dogs were successfully maintained using this cartridge to regenerate the hemodialysate. After completion of human studies the system was placed on the market in 1973. Three major problems occurred in the first year of marketing: 1. Displacement of the urease by the liquid in the Cordis‐Dow dialysers. 2. Deafness after use with an unrinsed dialyser. 3. Inactivation of the urease by copper in the water supply. They were resolved by emptying the Cordis‐Dow dialyser, rinsing all dialyser before use and adding a scavenger layer to the cartridge. At first the major market for the REDY System was the home market. However, as this market shrank the major market became dialysis of the acute renal failure patient. After it was found that the eluant from the cartridge sometimes contained aluminium, the alumina in the zirconium layers was removed and the present cartridge no longed contributes aluminium to the dialysate but also can be used to remove aluminium from hemodialysate. Attempts have been made to use the system to develop a wearable kidney.