title: Characteristics of an albumin dialysate hemodiafiltration system for the clearance of unconjugated bilirubin.
abstract: Extraction of protein bound liver failure toxins, such as unconjugated bilirubin, short chain fatty acids, and aromatic amino acids has been reported using hemodiafiltration with albumin in the dialysate, but the characteristics of such a system have not been described. Therefore, bilirubin clearance using albumin dialysate hemodiafiltration was evaluated in the setting of different dialysate albumin concentrations, varying temperature and pH. An in vitro continuous hemodiafiltration circuit was used with single pass countercurrent dialysis. Unconjugated bilirubin was added to bovine blood and filtered across a polyalkyl sulfone (PAS) hemofilter using matched filtration and dialysate flow rates. The serial bilirubin content was measured and first order clearance kinetics verified. The clearance rate constants were calculated for three dialysate groups of different albumin concentration at constant temperature and pH (group 1: 10 g/dl albumin, n = 5; 2 g/dl albumin, n = 5; normal saline, n = 5), and three groups of different temperature and pH at constant albumin dialysate concentration (group 2: pH = 7.0, temperature = 20 degrees C, n = 5; pH = 7.5, temperature = 20 degrees C, n = 5; pH = 7.0, temperature = 40 degrees C, n = 5). Comparisons were made with ANOVA and Tukey post hoc analysis. When albumin was used in the dialysate, the 2 g/dl group cleared bilirubin 3.1 times faster than saline alone (p = 0.001), and the 10 g/dl group was superior to both (p = 0.001). There were no measurable differences between the 2 g/dl groups at the various temperatures tested (p = 0.08), but the clearance was less at a pH of 7.5 (p = 0.015). The clearance of unconjugated bilirubin is greatly enhanced with the use of albumin containing dialysates when compared to traditional crystalloid hemodiafiltration, is greater at lower pH, and seems to be unaffected by temperature.
authors.affiliation: Department of Surgery, University of Michigan Hospitals, Ann Arbor 48109-0331, USA.
authors.forename: S S
authors.initials: SS
authors.lastname: Awad
authors.forename: P B
authors.initials: PB
authors.lastname: Rich
authors.forename: S
authors.initials: S
authors.lastname: Kolla
authors.forename: J G
authors.initials: JG
authors.lastname: Younger
authors.forename: C A
authors.initials: CA
authors.lastname: Reickert
authors.forename: V P
authors.initials: VP
authors.lastname: Downing
authors.forename: R H
authors.initials: RH
authors.lastname: Bartlett
mesh_terms: D000418:Albumins; D000818:Animals; D001663:Bilirubin / Q000097:blood* / Q000302:isolation & purification*; D002417:Cattle; D005069:Evaluation Studies as Topic; D017583:Hemodiafiltration / Q000295:instrumentation / Q000379:methods*; D015312:Hemodialysis Solutions; D006501:Hepatic Encephalopathy / Q000097:blood / Q000628:therapy; D006801:Humans; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D013696:Temperature
chemical_list: D000418:Albumins; D015312:Hemodialysis Solutions; D001663:Bilirubin