title: Effects of efficiency and length of acetate-free biofiltration session on postdialysis solute rebound.
abstract: BACKGROUND
  Postdialytic rebound (PDR) of plasma solutes is a relevant drawback of intermittent hemodialysis, but its pathophysiological process remains undefined. We assessed the independent effects of efficiency and length of dialytic session on PDR of urea, phosphate, and potassium.
  
  
  METHODS
  Uremic patients were evaluated at the beginning and end of dialysis and after 180 minutes in 2 randomized crossover studies. In study 1, we compared the effect of standard versus higher efficiency acetate-free biofiltration (AFB) while maintaining the same duration of 4 hours. In study 2, we compared the effect of 3- versus 5-hour AFB sessions while maintaining similar efficiency.
  
  
  RESULTS
  In study 1, greater Kt/V (1.49 +/- 0.20 versus 1.22 +/- 0.15; P < 0.0001) was coupled with significant increases in both absolute removal and PDR of urea and phosphate (PDR of urea, +45% versus +29%; PDR of phosphate, +79% versus +52%), but not of potassium. Similarly, in study 2, shortening the AFB session while maintaining similar absolute removal and Kt/V (1.28 +/- 0.09 versus 1.31 +/- 0.09) significantly increased PDR of urea and phosphate (PDR of urea, +32% versus +19%; PDR of phosphate, +63% versus +36%), but not of potassium. In both studies, greater PDRs of urea and phosphate were associated with estimated greater removal of these solutes per hour.
  
  
  CONCLUSIONS
  The rate of removal of phosphate and urea is a critical determinant of their PDR; conversely, potassium is not influenced by removal rate, likely because of its marked cell compartmentalization.
authors.affiliation: Nephrology and Dialysis Unit, School of Medicine, Second University of Naples, Country Hospital in Solofra, Naples, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Giannattasio
authors.forename: Roberto
authors.initials: R
authors.lastname: Minutolo
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Bellizzi
authors.forename: Biagio R
authors.initials: BR
authors.lastname: Di Iorio
authors.forename: Raffaele
authors.initials: R
authors.lastname: Scigliano
authors.forename: Pasquale
authors.initials: P
authors.lastname: Zamboli
authors.forename: Guglielmo
authors.initials: G
authors.lastname: Venditti
authors.forename: Rocco
authors.initials: R
authors.lastname: Manganelli
authors.forename: Walter
authors.initials: W
authors.lastname: De Simone
authors.forename: Filippo
authors.initials: F
authors.lastname: Aucella
authors.forename: Carmine
authors.initials: C
authors.lastname: Stallone
authors.forename: Stefano
authors.initials: S
authors.lastname: Spiezia
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Conte
authors.forename: Luca
authors.initials: L
authors.lastname: De Nicola
mesh_terms: D000085:Acetates / Q000032:analysis; D000328:Adult; D018592:Cross-Over Studies; D005260:Female; D015312:Hemodialysis Solutions / Q000737:chemistry / Q000627:therapeutic use*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood; D010710:Phosphates / Q000097:blood*; D011188:Potassium / Q000097:blood*; D006435:Renal Dialysis / Q000379:methods*; D013997:Time Factors; D014508:Urea / Q000097:blood*; D014511:Uremia / Q000097:blood* / Q000628:therapy*
chemical_list: D000085:Acetates; D015312:Hemodialysis Solutions; D010281:Parathyroid Hormone; D010710:Phosphates; D014508:Urea; D011188:Potassium