Wearable artificial kidneys for continuous dialysis. A personal view.

Since 1971, the author has been actively promoting and working on a wearable artificial kidney for continuous dialysis. Such a kidney could allow the patient to have a more normal life style, eliminate treatment scheduling, and provide stable chemistries. Two partially successful wearable kidneys based upon hemofiltration have been devised. One required the patient to drink a liter of dialysate every hour to replace ultrafiltrate loss, and the other regenerated the ultrafiltrate with a REDY sorbent cartridge. Although the patients underwent anticoagulation, their hemofilters clotted in fewer than 5 days. In addition, there was a serious risk of bleeding in the event of accidental injuries. Use of a peritoneal access eliminates these blood related problems. Continuous ambulatory peritoneal dialysis (CAPD) is a successful continuously wearable kidney, but the bag changes are a chore. This drawback often produces technique failure, resulting in the patient shifting to hemodialysis. Regeneration of peritoneal dialysis has been performed successfully in intermittent peritoneal dialysis, but the higher concentration of protein in spent CAPD fluid interfered with performance of the sorbent cartridge. The author demonstrated that removing the protein by filtration through a hemofilter before regeneration resolves this problem, permitting development of a viable wearable kidney.