title: Assessment of dialyzer surface in online hemodiafiltration; objective choice of dialyzer surface area.
abstract: BACKGROUND
  Online hemodiafiltration (OL-HDF) is currently the most effective technique. Several randomized studies and meta-analyses have observed a reduction in mortality as well as a direct association with convective volume. Currently, it has not been well established whether a larger dialyzer surface area could provide better results in terms of convective and depurative effectiveness. The aim of this study was to assess the effect of larger dialyzer surface areas on convective volume and filtration capacity.
  
  
  METHODS
  A total of 37 patients were studied, including 31 men and 6 women, who were in the OL-HDF program using a 5008 Cordiax monitor with auto-substitution. Each patient was analyzed in 3 sessions in which only the dialyzer surface area varied (1.0, 1.4 or 1.8 m(2)). The concentrations of urea (60 Da), creatinine (113 Da), β2-microglobulin (11800 Da), myoglobin (17200 Da) and α1-microglobulin (33000 Da) were determined in serum at the beginning and end of each session in order to calculate the percent reduction of these solutes.
  
  
  RESULTS
  The convective volume reached was 29.8 ± 3.0 with 1.0 m(2), 32.7 ± 3.1 (an increase of 6%) with 1.4 m(2), and 34.7 ± 3.3 L (an increase of 16%) with 1.8 m(2) (p<.001). The increased surface of the dialyzer showed an increase in the dialysis dose as well as urea and creatinine filtration. The percentage of β2m reduction increased from 80.0 ± 5.6 with 1.0 m(2) to 83.2 ± 4.2 with 1.4 m(2) and to 84.3 ± 4.0% with 1.8 m(2). As for myoglobin and a1-microglobulin, significant differences were observed between smaller surface area (1.0 m(2)) 65.6 ± 11 and 20.1 ± 9.3 and the other two surface areas, which were 70.0 ± 8.1 and 24.1 ± 7.1 (1.4 m(2)) and 72.3 ± 8.7 and 28.6 ± 12 (1.8 m(2)).
  
  
  CONCLUSIONS
  The 40% and 80% increases in surface area led to increased convective volumes of 6 and 16% respectively, while showing minimal differences in both the convective volume as well as the filtration capacity when the CUF was higher than 45 ml/h/mmHg. It is recommended to optimize the performance of dialyzers with the minimal surface area possible when adjusting the treatment prescription.
authors: Servicio de Nefrología y Trasplante Renal, Hospital Clínic, Barcelona, España. Electronic address: fmaduell@clinic.ub.es.
authors: Francisco
authors: F
authors: Maduell
authors: Servicio de Nefrología y Trasplante Renal, Hospital Clínic, Barcelona, España.
authors: Raquel
authors: R
authors: Ojeda
authors: Servicio de Nefrología y Trasplante Renal, Hospital Clínic, Barcelona, España.
authors: Marta
authors: M
authors: Arias-Guillén
authors: Servicio de Nefrología y Trasplante Renal, Hospital Clínic, Barcelona, España.
authors: Giannina
authors: G
authors: Bazan
authors: Servicio de Nefrología y Trasplante Renal, Hospital Clínic, Barcelona, España.
authors: Manel
authors: M
authors: Vera
authors: Servicio de Nefrología y Trasplante Renal, Hospital Clínic, Barcelona, España.
authors: Néstor
authors: N
authors: Fontseré
authors: Servicio de Nefrología y Trasplante Renal, Hospital Clínic, Barcelona, España.
authors: Elisabeth
authors: E
authors: Massó
authors: Servicio de Nefrología y Trasplante Renal, Hospital Clínic, Barcelona, España.
authors: Miquel
authors: M
authors: Gómez
authors: Servicio de Nefrología y Trasplante Renal, Hospital Clínic, Barcelona, España.
authors: Lida
authors: L
authors: Rodas
authors: Servicio de Nefrología y Trasplante Renal, Hospital Clínic, Barcelona, España.
authors: Mario
authors: M
authors: Jiménez-Hernández
authors: Servicio de Nefrología y Trasplante Renal, Hospital Clínic, Barcelona, España.
authors: Gastón
authors: G
authors: Piñeiro
authors: Servicio de Bioquímica, Hospital Clínic, Barcelona, España.
authors: Nayra
authors: N
authors: Rico
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers; D018481:Convection; D003404:Creatinine / Q000097:blood; D004867:Equipment Design; D005260:Female; D017583:Hemodiafiltration / Q000295:instrumentation*; D006801:Humans; D007676:Kidney Failure, Chronic / Q000097:blood / Q000628:therapy; D008297:Male; D008875:Middle Aged; D009211:Myoglobin / Q000097:blood; D014508:Urea / Q000097:blood; D001613:beta 2-Microglobulin / Q000032:analysis
chemical_list: D015415:Biomarkers; D009211:Myoglobin; D001613:beta 2-Microglobulin; D014508:Urea; D003404:Creatinine
keywords: Autosubstitution; Autosustitución; Convective volume; Hemodiafiltración on-line; Membrane surface; Online hemodiafiltration (OL-HDF); Superficie de membrana; Volumen convectivo