No abstract

The elimination of uremic substances is achieved in hemodialysis by diffusion from the blood to a modified Ringer's solution. In contrast to this effect, in which the elimination rate of substances is directly correlated to their molecular weight, the removal of waste products in hemofiltration is achieved by means of a convective transport, which is independent of the molecular weight, but dependent on the cutoff of the membrane and the filtrate flow. Hemofiltration, thus, resembles the filtration process of the natural kidney more closely than hemodialysis and peritoneal dialysis do. Having obtained promising results in the course of a pilot study (1), a study to compare hemodialysis with hemofiltration under standardized conditions was started in 1978 under the auspices of the NIH. Two groups of patients with stable chronic renal failure, were treated on an A-B-A (group I) and a B-A-B (group II) sequence (A=hemodialysis and B=hemofiltration). Each treatment period lasted for 5 months.