title: Protein-bound solute removal during extended multipass versus standard hemodialysis.
abstract: BACKGROUND
  Multipass hemodialysis (MPHD) is a recently described dialysis modality, involving the use of small volumes of dialysate which are repetitively recycled. Dialysis regimes of 8 hours for six days a week using this device result in an increased removal of small water soluble solutes and middle molecules compared to standard hemodialysis (SHD). Since protein-bound solutes (PBS) exert important pathophysiological effects, we investigated whether MPHD results in improved removal of PBS as well.
  
  
  METHODS
  A cross-over study (Clinical Trial NCT01267760) was performed in nine stable HD patients. At midweek a single dialysis session was performed with either 4 hours SHD using a dialysate flow of 500 mL/min or 8 hours MPHD with a dialysate volume of 50% of estimated body water volume. Blood and dialysate samples were taken every hour to determine concentrations of p-cresylglucuronide (PCG), hippuric acid (HA), indole acetic acid (IAA), indoxyl sulfate (IS), and p-cresylsulfate (PCS). Dialyser extraction ratio, reduction ratio, and solute removal were calculated for these solutes.
  
  
  RESULTS
  Already at 60 min after dialysis start, the extraction ratio in the hemodialyser was a factor 1.4-4 lower with MPHD versus SHD, resulting in significantly smaller reduction ratios and lower solute removal within a single session. Even when extrapolating our findings to 3 times 4 h SHD and 6 times 8 h MPHD per week, the latter modality was at best similar in terms of total solute removal for most protein-bound solutes, and worse for the highly protein-bound solutes IS and PCS. When efficiency was calculated as solute removal/litre of dialysate used, MPHD was found superior to SHD.
  
  
  CONCLUSIONS
  When high water consumption is a concern, a treatment regimen of 6 times/week 8 h MPHD might be an alternative for 3 times/week 4 h SHD, but at the expense of a lower total solute removal of highly protein-bound solutes.
authors.affiliation: Department of Nephrology, Ghent University Hospital, De Pintelaan 185, 9000, Ghent, Belgium. sunny.eloot@ugent.be.
authors.forename: Sunny
authors.initials: S
authors.lastname: Eloot
authors.affiliation: Department of Nephrology, Ghent University Hospital, De Pintelaan 185, 9000, Ghent, Belgium. wim.vanbiesen@ugent.be.
authors.forename: Wim
authors.initials: W
authors.lastname: Van Biesen
authors.affiliation: Institute of Public Health, Aarhus University, Nordre Ringgade 1, 8000, Aarhus C, Denmark. metaxels@rm.dk.
authors.forename: Mette
authors.initials: M
authors.lastname: Axelsen
authors.affiliation: Department of Nephrology, Ghent University Hospital, De Pintelaan 185, 9000, Ghent, Belgium. griet.glorieux@ugent.be.
authors.forename: Griet
authors.initials: G
authors.lastname: Glorieux
authors.affiliation: Flexdialysis Aps, Copenhagen, Denmark.
authors.forename: Robert Smith
authors.initials: RS
authors.lastname: Pedersen
authors.affiliation: Department of Nephrology, Herlev Hospital, University of Copenhagen, Copenhagen, Denmark. d110582@dadlnet.dk.
authors.forename: James Goya
authors.initials: JG
authors.lastname: Heaf
mesh_terms: D000368:Aged; D001071:Appointments and Schedules; D018592:Cross-Over Studies; D005260:Female; D015312:Hemodialysis Solutions; D006801:Humans; D007676:Kidney Failure, Chronic / Q000175:diagnosis / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011506:Proteins; D006435:Renal Dialysis / Q000379:methods / Q000592:standards*; D013997:Time Factors; D016896:Treatment Outcome; D014462:Ultrafiltration / Q000379:methods / Q000592:standards; D014508:Urea / Q000032:analysis; D014527:Uric Acid / Q000032:analysis
chemical_list: D015312:Hemodialysis Solutions; D011506:Proteins; D014527:Uric Acid; D014508:Urea