Assessment of dialyzer surface in online hemodiafiltration; objective choice of dialyzer surface area

摘要

Introduction Online haemodiafiltration (OL-HDF) is most effective technique; several randomised studies and meta-analyses have shown a reduction in mortality, with a directly related association with convective volume. At present, it is not properly established whether the increasing in dialyser surface area may suppose better outcomes in terms of convective and clearance efficacy. The purpose of the study was to assess the effect of increase in dialyser surface area on the convective volume and clearance capacity. Materials and methods A total of 37 patients were included, 31 male and 6 female subjects who were participating in an OL-HDF programme with a 5008 Cordiax monitor with autosubstitution. Each patient was analysed in three sessions, and only the dialyser surface area (1.0, 1.4 or 1.8m 2 ) varied. In each session, urea (60Da), creatinine (113Da), β 2 -microglobulin (11,800Da), myoglobin (17,200Da) and α 1 -microglobulin (33,000Da) serum concentration at baseline and at the end of each session were determined, so the reduction of thes solutes could be calculated. Results Convective volume achieved was 29.8±3.0 with 1.0m 2 , 32.7±3.1 (6% increase) with 1.4m 2 and 34.7±3.3L (16% increase) with 1.8m 2 ( p <0.001). The increase in dialyser surface area showed an increase in urea and Creatinine clearance and urea and creatinine clearance. The reduction percentage of β 2 -m increased from 80.0±5.6 with 1.0m 2 , to 83.2±4.2 with 1.4m 2 and to 84.3±4.0% with 1.8m 2 . Regarding myoglobin and α 1 -microglobulin, significant differences were observed between the smallest surface area (1.0m 2 ), 65.6±11 and 20.1±9.3 and the other two surface areas, 70.0±8.1 and 24.1±7.1 (1.4m 2 ) and 72.3±8.7 and 28.6±12 (1.8m 2 ). Conclusion The increase in 40% and 80% of dialyzer surface area entails an increase in convective volume of 6 and 16% respectively, showing minimal differences both in convective volume and clearance capacity when UFC was greater than 45mL/h/mmHg. It is advisable to optimise dialyser efficiency to the smallest surface area possible, adjusting treatment prescription.