title: Improvement in sleep apnea during nocturnal peritoneal dialysis is associated with reduced airway congestion and better uremic clearance.
abstract: OBJECTIVE
  Among peritoneal dialysis (PD) patients, nocturnal PD (NPD) is known to improve sleep apnea compared with continuous ambulatory peritoneal dialysis (CAPD), but the contributing factors are unclear.
  
  
  METHODS
  Thirty-eight incident ESRD patients underwent overnight polysomnography (PSG) during NPD and CAPD. Bioelectrical impedance analysis, magnetic resonance imaging of the upper airway, and urea kinetics (Kt/V) during sleep were measured on both occasions.
  
  
  RESULTS
  The prevalence of severe sleep apnea (apnea-hypopnea index, AHI > or = 15/h) was 21.1% during NPD, and 42.1% during CAPD. Mean AHI increased from 9.6 +/- 2.7/h during NPD to 21.5 +/- 4.2/h during CAPD. Both obstructive and central apnea worsened after conversion to CAPD. NPD achieved greater reductions in total body water, hydration fraction, and net ultrafiltration than CAPD during sleep. Overnight peritoneal Kt/V and creatinine clearance were lower after conversion. Both peritoneal Kt/V and peritoneal creatinine clearance correlated with AHI, as did their changes after conversion. Volumetric magnetic resonance imaging revealed reduced pharyngeal volumes and cross-sectional area, and tongue enlargement after conversion.
  
  
  CONCLUSIONS
  Improvement in sleep apnea during NPD versus CAPD is associated with better fluid and uremic clearance and reduced upper airway congestion during sleep.
authors.affiliation: Division of Nephrology, Department of Medicine, The University of Hong Kong and Queen Mary Hospital, Hong Kong, China.
authors.forename: Sydney C W
authors.initials: SC
authors.lastname: Tang
authors.forename: Bing
authors.initials: B
authors.lastname: Lam
authors.forename: Andrew S H
authors.initials: AS
authors.lastname: Lai
authors.forename: Clara B Y
authors.initials: CB
authors.lastname: Pang
authors.forename: Wai Kuen
authors.initials: WK
authors.lastname: Tso
authors.forename: Pek Lan
authors.initials: PL
authors.lastname: Khong
authors.forename: Mary S M
authors.initials: MS
authors.lastname: Ip
authors.forename: Kar Neng
authors.initials: KN
authors.lastname: Lai
mesh_terms: D000328:Adult; D000368:Aged; D002940:Circadian Rhythm; D003404:Creatinine / Q000378:metabolism; D018592:Cross-Over Studies; D017097:Electric Impedance; D005260:Female; D006801:Humans; D007676:Kidney Failure, Chronic / Q000150:complications / Q000378:metabolism / Q000473:pathology / Q000628:therapy*; D007700:Kinetics; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010530:Peritoneal Dialysis / Q000009:adverse effects / Q000379:methods*; D010531:Peritoneal Dialysis, Continuous Ambulatory / Q000009:adverse effects; D017286:Polysomnography; D012137:Respiratory System / Q000473:pathology*; D012720:Severity of Illness Index; D012891:Sleep Apnea Syndromes / Q000209:etiology / Q000517:prevention & control*; D014508:Urea / Q000378:metabolism; D014511:Uremia / Q000209:etiology / Q000378:metabolism / Q000473:pathology / Q000628:therapy*
chemical_list: D014508:Urea; D003404:Creatinine