title: A randomized, double crossover study to investigate the influence of saline infusion on sleep apnea severity in men.
abstract: OBJECTIVE
  Obstructive sleep apnea (OSA) is commoner in patients with fluid-retaining states than in those without fluid retention, in men than in women, and worsens with aging. In men, OSA severity is related to the amount of fluid shifting out of the legs overnight, but a cause-effect relationship is not established. Our objective was to test the hypothesis that mimicking fluid overload during sleep would increase severity of OSA more in older (≥ 40 years) than in younger men (< 40 years).
  
  
  METHODS
  Randomized, single-blind, double crossover study.
  
  
  METHODS
  Research sleep laboratory.
  
  
  METHODS
  Seven older and 10 younger men with non-severe or no sleep apnea, matched for body mass index.
  
  
  METHODS
  During the control arm, normal saline was infused to keep the vein open. During intervention, subjects received an intravenous bolus of normal saline (22 mL/kg body weight) after sleep onset while they were wearing compression stockings to prevent fluid accumulation in the legs.
  
  
  RESULTS
  Compared to younger men, infusion of similar amounts of saline in older men caused a greater increase in neck circumference (P < 0.05) and in the AHI (32.2 ± 22.1 vs. 2.2 ± 7.1, P = 0.002).
  
  
  CONCLUSIONS
  Older men are more susceptible to the adverse effects of intravenous fluid loading on obstructive sleep apnea severity than younger men. This may be due to age-related differences in the amount of fluid accumulating in the neck or upper airway collapsibility in response to intravenous fluid loading. These possibilities remain to be tested in future studies.
authors.affiliation: Sleep Research Laboratory, University Health Network, Toronto Rehabilitation Institute, Toronto, Canada and Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Canada.
authors.forename: Azadeh
authors.initials: A
authors.lastname: Yadollahi
authors.affiliation: Sleep Research Laboratory, University Health Network, Toronto Rehabilitation Institute, Toronto, Canada and Institute of Medical Science, University of Toronto, Toronto, Canada.
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Gabriel
authors.affiliation: Sleep Research Laboratory, University Health Network, Toronto Rehabilitation Institute, Toronto, Canada and Centre for Sleep Medicine and Circadian Biology, University of Toronto, Toronto, Canada and Department of Medicine, University Health Network, Toronto General Hospital, Toronto, Canada.
authors.forename: Laura H
authors.initials: LH
authors.lastname: White
authors.affiliation: Sleep Research Laboratory, University Health Network, Toronto Rehabilitation Institute, Toronto, Canada and Centre for Sleep Medicine and Circadian Biology, University of Toronto, Toronto, Canada.
authors.forename: Luigi
authors.initials: L
authors.lastname: Taranto Montemurro
authors.affiliation: Sleep Research Laboratory, University Health Network, Toronto Rehabilitation Institute, Toronto, Canada and Centre for Sleep Medicine and Circadian Biology, University of Toronto, Toronto, Canada.
authors.forename: Takatoshi
authors.initials: T
authors.lastname: Kasai
authors.affiliation: Sleep Research Laboratory, University Health Network, Toronto Rehabilitation Institute, Toronto, Canada and Centre for Sleep Medicine and Circadian Biology, University of Toronto, Toronto, Canada and Department of Medicine, University Health Network, Toronto General Hospital, Toronto, Canada.
authors.forename: T Douglas
authors.initials: TD
authors.lastname: Bradley
mesh_terms: D061605:Administration, Intravenous; D000328:Adult; D000375:Aging / Q000502:physiology*; D015992:Body Mass Index; D018592:Cross-Over Studies; D018495:Fluid Shifts / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D007866:Leg / Q000502:physiology; D008297:Male; D008875:Middle Aged; D009333:Neck / Q000033:anatomy & histology; D017286:Polysomnography; D016037:Single-Blind Method; D012890:Sleep / Q000187:drug effects* / Q000502:physiology; D020181:Sleep Apnea, Obstructive / Q000503:physiopathology*; D012965:Sodium Chloride / Q000008:administration & dosage* / Q000494:pharmacology*; D053828:Stockings, Compression
chemical_list: D012965:Sodium Chloride
keywords: age; blood pressure; fluid overloading; male sex; obstructive sleep apnea