[Comparison of repeated use of capillary dialysators model C-DAK 4 and C-DAK 5]

18 dialysators C-DAK 5 and 4 each were again used in the same patients with chronic dialysis under the same conditions of dialysis and regeneration (short-acting dialyses of more than 3.5 h with 1 C-DAK 5 or 2 parallel acting C-DAK 4, respectively). A volume of the blood compartment of more than 70% of the initial value was regarded as criterion for the further usability. Thus, model 5 could be used on an average 3.7 times, model 4, however, 6.3 times (p less than 0.0001). Already at the end of the 3rd use in model 5 the capillary volume decreased below 63%, in model 4 only below 88%. The volumetrically determined ultrafiltration showed a decrease parallel to the volume of the blood compartment -- with the same differences between the two models of the C-DAK. In model 15 the effectiveness concerning the elimination of creatinine and urea clearly decreased after the 2nd use, whereas it did not reveal a change also in an application four times repeated. The larger coagulation processes in a more than once repeated use of the C-DAK 5 -- with adequate losses of blood -- are explained with the large length of the capillary and the other distribution of blood with regard to the cross section of the capillary. Summarizing we can say that in chronic routine dialyses -- without testing the individual exemplars -- model 5 of the C-DAK can be used twice, model 4, however, four times.