Using haemodiafiltration--a combination of haemodialysis and haemofiltration--an increased clearance rate for middle and small molecules can be obtained compared to the single technique alone. Low molecular weight substances are removed mainly by diffusion, and middle molecules predominantly by convection. Using currently available equipment the duration of therapy can thus be reduced by at least one-third, compared with haemodialysis, without deterioration in the patient's general condition. The withdrawal of large volumes of fluid is markedly better tolerated by the patient than with other short-time blood purification procedures. With the aid of haemodiafiltration both molecular groups can be diminished independently of each other according to individual demand, thereby leading to optimization of dialysis therapy.
