title: Obstructive Sleep Apnea Severity and Overnight Body Fluid Shift before and after Hemodialysis.
abstract: OBJECTIVE
  Obstructive sleep apnea is associated with significantly increased cardiovascular morbidity and mortality. Fluid overload may promote obstructive sleep apnea in patients with ESRD through an overnight fluid shift from the legs to the neck soft tissues. Body fluid shift and severity of obstructive sleep apnea before and after hemodialysis were compared in patients with ESRD.
  
  
  METHODS
  Seventeen patients with hemodialysis and moderate to severe obstructive sleep apnea were included. Polysomnographies were performed the night before and after hemodialysis to assess obstructive sleep apnea, and bioimpedance was used to measure fluid overload and leg fluid volume.
  
  
  RESULTS
  The mean overnight rostral fluid shift was 1.27±0.41 L prehemodialysis; it correlated positively with fluid overload volume (r=0.39; P=0.02) and was significantly lower posthemodialysis (0.78±0.38 L; P<0.001). There was no significant difference in the mean obstructive apnea-hypopnea index before and after hemodialysis (46.8±22.0 versus 42.1±18.6 per hour; P=0.21), but obstructive apnea-hypopnea index was significantly lower posthemodialysis (-10.1±10.8 per hour) in the group of 12 patients, with a concomitant reduction of fluid overload compared with participants without change in fluid overload (obstructive apnea-hypopnea index +8.2±16.1 per hour; P<0.01). A lower fluid overload after hemodialysis was significantly correlated (r=0.49; P=0.04) with a lower obstructive apnea-hypopnea index. Fluid overload-assessed by bioimpedance-was the best predictor of the change in obstructive apnea-hypopnea index observed after hemodialysis (standardized r=-0.68; P=0.01) in multivariate regression analysis.
  
  
  CONCLUSIONS
  Fluid overload influences overnight rostral fluid shift and obstructive sleep apnea severity in patients with ESRD undergoing intermittent hemodialysis. Although no benefit of hemodialysis on obstructive sleep apnea severity was observed in the whole group, the change in obstructive apnea-hypopnea index was significantly correlated with the change in fluid overload after hemodialysis. Moreover, the subgroup with lower fluid overload posthemodialysis showed a significantly lower obstructive sleep apnea severity, which provides a strong incentive to further study whether optimizing fluid status in patients with obstructive sleep apnea and ESRD will improve the obstructive apnea-hypopnea index.
authors: Center for Investigation and Research in Sleep, Service of Respiratory Medicine, and adam.ogna@chuv.ch.
authors: Adam
authors: A
authors: Ogna
authors: Service of Nephrology and Hypertension, University Hospital of Lausanne, Lausanne, Switzerland;
authors: Valentina
authors: V
authors: Forni Ogna
authors: Center for Investigation and Research in Sleep, Service of Respiratory Medicine, and.
authors: Alexandra
authors: A
authors: Mihalache
authors: Service of Nephrology and Hypertension, University Hospital of Lausanne, Lausanne, Switzerland;
authors: Menno
authors: M
authors: Pruijm
authors: Hemodialysis Unit, Northern Vaud Hospitals, Yverdon, Switzerland; and.
authors: Georges
authors: G
authors: Halabi
authors: Hemodialysis Unit, Intercantonal Hospital, Payerne, Switzerland.
authors: Olivier
authors: O
authors: Phan
authors: Center for Investigation and Research in Sleep.
authors: Françoise
authors: F
authors: Cornette
authors: Service of Nephrology and Hypertension, University Hospital of Lausanne, Lausanne, Switzerland;
authors: Isabelle
authors: I
authors: Bassi
authors: Center for Investigation and Research in Sleep.
authors: José
authors: J
authors: Haba Rubio
authors: Service of Nephrology and Hypertension, University Hospital of Lausanne, Lausanne, Switzerland;
authors: Michel
authors: M
authors: Burnier
authors: Center for Investigation and Research in Sleep, Service of Respiratory Medicine, and.
authors: Raphaël
authors: R
authors: Heinzer
mesh_terms: D000368:Aged; D001823:Body Composition; D017097:Electric Impedance; D005260:Female; D018495:Fluid Shifts; D006801:Humans; D007676:Kidney Failure, Chronic / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D011237:Predictive Value of Tests; D006435:Renal Dialysis; D012307:Risk Factors; D012720:Severity of Illness Index; D020181:Sleep Apnea, Obstructive / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology; D013557:Switzerland; D016896:Treatment Outcome
keywords: ESRD; hemodialysis; nocturnal hypoxemia; ultrafiltration; water-electrolyte balance