An in vitro comparison of capillary flow dialyzer performances on a single needle system (double headpump).

The ultrafiltration, clearance and priming characteristics of six capillary dialyzers (C-DAK 2.5 D, C-DAK 1.8 D, Tri-Ex 1, CF M 1500, N16F160 and HF 150) were studied in single needle dialysis by way of the double headpump (BL 760, Bellco Ltd). A good control of the ultrafiltration by an appropriate choice of the mean bloodcompartment pressures (Pbo) is present in all dialyzers. After correction of the clearance for ultrafiltration the clearances of urea, creatinine, sodiumiothalamate-l125 and cyanocobalamine-Co58 (vit. B 12) rise with increasing mean pressures in the bloodcompartment of all dialyzers. We assume that a better use of available surface area due to the characteristics of the double headpump such as TMP mainly influenced by Pbo pressures and other such as tidal flow are responsible for the excellent in vitro clearances of these dialyzers with this type of single needle system.