title: Predilution hemodiafiltration displays no hemodynamic advantage over low-flux hemodialysis under matched conditions.
abstract: BACKGROUND
  It is the prevailing view that convective dialysis techniques stabilize blood pressure. The aim of this study was to compare the intrasession hemodynamics during high-dose predilution hemodiafiltration (HDF) and low-flux hemodialsis, under strict controlled conditions.
  
  
  METHODS
  Twelve stable hemodialysis patients were investigated in a randomized crossover blinded controlled trial. The patients were allocated to one session of predilution HDF (substitution fluid 1.20 +/- 0.10 L/kg body weight) and one session of hemodialysis at 4(1/2) hours. To eliminate confounding factors, dialysis dose, ultrafiltration volume and arterial temperature were matched. At the start of the dialysis the patients' core temperature was "locked" by an automatic feedback system regulating the dialysate temperature; thereby, patients' temperature was kept stable throughout the whole treatment. The calcium-ion concentration in the substitution/dialysis fluid was 1.25 mmol/L. Cardiac output was measured hourly by the ultrasound velocity dilution method.
  
  
  RESULTS
  Mean blood pressure, cardiac output, stroke volume, cardiac work, and relative blood volume was significantly reduced in both treatments. Total peripheral resistance increased significantly in both groups. Ultrafiltration volume, cardiopulmonary recirculation, Kt/V, and total energy transfer were similar for hemodialysis and HDF. The pulse rate showed no significant change throughout both sessions. No significant differences were revealed between hemodialysis and HDF.
  
  
  CONCLUSIONS
  The hemodynamics of predilution HDF and low-flux hemodialysis displayed a similar profile during matched conditions. An acute circulatory benefit of convective solute removal over diffusive could not be demonstrated.
authors.affiliation: Department of Renal Medicine C, Skejby, Aarhus University Hospital, Aarhus, Denmark. karamperis@stofanet.dk
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Karamperis
authors.forename: Erik
authors.initials: E
authors.lastname: Sloth
authors.forename: Jens Dam
authors.initials: JD
authors.lastname: Jensen
mesh_terms: D001794:Blood Pressure; D001810:Blood Volume; D002302:Cardiac Output; D018592:Cross-Over Studies; D015314:Dialysis Solutions; D004311:Double-Blind Method; D017583:Hemodiafiltration / Q000379:methods*; D006439:Hemodynamics; D006801:Humans; D006435:Renal Dialysis / Q000379:methods*; D016896:Treatment Outcome; D014655:Vascular Resistance
chemical_list: D015314:Dialysis Solutions