title: Effect of below-the-knee compression stockings on severity of obstructive sleep apnea.
abstract: BACKGROUND
  Overnight fluid shift from the legs to the neck may narrow the upper airway and contribute to obstructive sleep apnea (OSA) pathogenesis. We hypothesized that below-the-knee compression stockings will decrease OSA severity in a general OSA population by decreasing daytime leg fluid accumulation and overnight fluid shift and increasing upper-airway size.
  
  
  METHODS
  Patients with OSA (apnea-hypopnea index ≥ 10) were randomized to wear compression stockings during the daytime or to a control group for 2 weeks. Overnight polysomnography with measurement of leg and neck fluid volumes and upper-airway cross-sectional area before and after sleep was performed at baseline and follow-up. The primary outcome was change in the apnea-hypopnea index.
  
  
  RESULTS
  Twenty-two patients randomized to compression stockings and 23 to control completed the study. The apnea-hypopnea index decreased significantly more in the compression stockings than in the control group (from 32.4 ± 20.0 to 23.8 ± 15.5 vs. from 31.2 ± 25.0 to 30.3 ± 23.8, p = 0.042), in association with a significantly greater reduction in the overnight decrease in leg fluid volume (p = 0.028), and a significantly greater increase in morning upper-airway cross-sectional area (p = 0.006). Overnight change in neck fluid volume was unchanged.
  
  
  CONCLUSIONS
  These observations suggest that in, a general OSA population, below-the-knee compression stockings decrease OSA severity modestly via attenuation of overnight fluid shift and consequent upper-airway dilatation.
authors.affiliation: Sleep Research Laboratory of the University Health Network Toronto Rehabilitation Institute, Toronto, ON, Canada; Centre for Sleep Medicine and Circadian Biology of the University of Toronto, Toronto, ON, Canada.
authors.forename: Laura H
authors.initials: LH
authors.lastname: White
authors.affiliation: Sleep Research Laboratory of the University Health Network Toronto Rehabilitation Institute, Toronto, ON, Canada; Centre for Sleep Medicine and Circadian Biology of the University of Toronto, Toronto, ON, Canada.
authors.forename: Owen D
authors.initials: OD
authors.lastname: Lyons
authors.affiliation: Sleep Research Laboratory of the University Health Network Toronto Rehabilitation Institute, Toronto, ON, Canada; Institute of Biomaterial and Biomedical Engineering, University of Toronto, Toronto, ON, Canada.
authors.forename: Azadeh
authors.initials: A
authors.lastname: Yadollahi
authors.affiliation: Sleep Research Laboratory of the University Health Network Toronto Rehabilitation Institute, Toronto, ON, Canada; Centre for Sleep Medicine and Circadian Biology of the University of Toronto, Toronto, ON, Canada; Department of Medicine of the University Health Network Toronto General Hospital, Toronto, ON, Canada.
authors.forename: Clodagh M
authors.initials: CM
authors.lastname: Ryan
authors.affiliation: Sleep Research Laboratory of the University Health Network Toronto Rehabilitation Institute, Toronto, ON, Canada; Centre for Sleep Medicine and Circadian Biology of the University of Toronto, Toronto, ON, Canada; Department of Medicine of the University Health Network Toronto General Hospital, Toronto, ON, Canada. Electronic address: douglas.bradley@utoronto.ca.
authors.forename: T Douglas
authors.initials: TD
authors.lastname: Bradley
mesh_terms: D001826:Body Fluids / Q000502:physiology; D005260:Female; D006801:Humans; D007866:Leg / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D010614:Pharynx / Q000503:physiopathology; D017286:Polysomnography; D012720:Severity of Illness Index; D020181:Sleep Apnea, Obstructive / Q000503:physiopathology / Q000628:therapy*; D053828:Stockings, Compression; D016896:Treatment Outcome
keywords: Compression stockings; Fluid shifts; Obstructive sleep apnea; Upper airway