title: Effect of ultrafiltration on sleep apnea and sleep structure in patients with end-stage renal disease.
abstract: BACKGROUND
  In end-stage renal disease (ESRD), a condition characterized by fluid overload, both obstructive and central sleep apnea (OSA and CSA) are common. This observation suggests that fluid overload is involved in the pathogenesis of OSA and CSA in this condition.
  
  
  OBJECTIVE
  To test the hypothesis that fluid removal by ultrafiltration (UF) will reduce severity of OSA and CSA in patients with ESRD.
  
  
  METHODS
  At baseline, on a nondialysis day, patients with ESRD on thrice-weekly hemodialysis underwent overnight polysomnography along with measurement of total body extracellular fluid volume (ECFV), and ECFV of the neck, thorax, and right leg before and after sleep. The following week, on a nondialysis day, subjects with an apnea-hypopnea index (AHI) greater than or equal to 20 had fluid removed by UF, followed by repeat overnight polysomnography with fluid measurements.
  
  
  RESULTS
  Fifteen patients (10 men) with an AHI greater than or equal to 20 (10 OSA; 5 CSA) participated. Mean age was 53.5 ± 10.4 years and mean body mass index was 25.3 ± 4.8 kg/m(2). Following removal of 2.17 ± 0.45 L by UF, the AHI decreased by 36% (43.8 ± 20.3 to 28.0 ± 17.7; P < 0.001) without affecting uremia. The reduction in AHI correlated with the reduction in total body ECFV (r = 0.567; P = 0.027) and was associated with reductions in ECFV of the right leg (P = 0.001), overnight change in ECFV of the right leg (P = 0.044), ECFV of the thorax (P = 0.001), and ECFV of the neck (P = 0.003).
  
  
  CONCLUSIONS
  These findings indicate that fluid overload contributes to the pathogenesis of OSA and CSA in ESRD, and that fluid removal by UF attenuates sleep apnea without altering uremic status.
authors.affiliation: 1 Sleep Research Laboratory, University Health Network Toronto Rehabilitation Institute, Toronto, Canada.
authors.forename: Owen D
authors.initials: OD
authors.lastname: Lyons
authors.forename: Christopher T
authors.initials: CT
authors.lastname: Chan
authors.forename: Azadeh
authors.initials: A
authors.lastname: Yadollahi
authors.forename: T Douglas
authors.initials: TD
authors.lastname: Bradley
mesh_terms: D005260:Female; D006440:Hemofiltration / Q000379:methods*; D006801:Humans; D007676:Kidney Failure, Chronic / Q000150:complications* / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D017286:Polysomnography / Q000379:methods; D006435:Renal Dialysis / Q000379:methods; D012720:Severity of Illness Index; D012890:Sleep; D012891:Sleep Apnea Syndromes / Q000150:complications* / Q000517:prevention & control*
keywords: fluid overload; hemodialysis; renal disease; sleep apnea