title: Biofeedback controlled hemodialysis (BF-HD) reduces symptoms and increases both hemodynamic tolerability and dialysis adequacy in non-hypotension prone stable patients.
abstract: BACKGROUND
  It is now possible to link relative blood volume (RBV) measurements to a software loop designed to actuate a biofeedback response. This allows changes in RBV to determine constant alterations in both ultrafiltration rate and dialysate conductivity. RBV, plasma sodium and weight loss are driven throughout the treatment to achieve the best compromise. This system has been demonstrated to markedly reduce intradialytic hypotension in unstable patients. We have applied this treatment to stable, non-hypotension prone HD patients and report on the short-term outcomes.
  
  
  METHODS
  We prospectively studied all 15 patients in a dedicated 4-station minimal care treatment area. Patients were studied for 3 weeks of standard HD, to understand the morphology and response to RBV in that individual. BF-HD was then instituted for a similar period (after a 2-week optimization period). Dialysis adequacy was assessed with equilibrated Kt/V measurements and urea mass removed in spent dialysate.
  
  
  RESULTS
  We studied 263 treatment sessions. There was a reduction in symptomatic episodes (per patient over 3 weeks) from 3 +/- 0.5 (0-9) to 0.13 +/- 0.13 (0-2) with BF-HD, p < 0.001. Reductions in systolic BP > 40% fell from 1.4 +/- 0.4 (0-4) to 0.46 +/- 0.16 (0-2). Episodes of RBV falling > 10% fell from 6.3 +/- 0.85 (1-13) to 1.13 +/- 0.27 (0-4) with BF-HD, p < 0.001. Interdialytic weight gains fell from 2.08 +/- 0.05 (0.35-3.8) kg to 1.82 +/- 0.06 (0-3.7) kg, p = 0.009. Equilibrated Kt/V increased from 1.01 +/- 0.03 (0.61-1.35) to 1.13 +/- 0.03 (0.7-1.5), p = 0.01, and mass removed of urea increased from 24.9 +/- 3 (12.8-45) g to 32.7 +/- 1.9 (17.3-48.5) g.
  
  
  CONCLUSIONS
  This is the first report of BF-HD increasing tolerability, reducing interdialytic fluid gains and enhancing urea clearance in non-hypotension prone chronic HD patients. These data suggest that the previously reported associated benefits of BF-HD may be applicable to the majority of HD patients.
authors.affiliation: Department of Renal Medicine, Derby City General Hospital, Derby, UK. chris-mcintyre@lineone.net
authors.forename: C W
authors.initials: CW
authors.lastname: McIntyre
authors.forename: S H
authors.initials: SH
authors.lastname: Lambie
authors.forename: R J
authors.initials: RJ
authors.lastname: Fluck
mesh_terms: D000328:Adult; D000368:Aged; D001794:Blood Pressure / Q000502:physiology; D001811:Blood Volume Determination / Q000379:methods; D005246:Feedback; D005260:Female; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D007022:Hypotension / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control*; D007676:Kidney Failure, Chronic / Q000503:physiopathology / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D006435:Renal Dialysis / Q000009:adverse effects / Q000379:methods*; D012984:Software; D014508:Urea / Q000652:urine; D015430:Weight Gain / Q000502:physiology
chemical_list: D014508:Urea