title: Overnight fluid shifts in subjects with and without obstructive sleep apnea.
abstract: OBJECTIVE
  To investigate the characteristics of baseline body fluid content and overnight fluid shifts between non-obstructive sleep apnea (non-OSA) and obstructive sleep apnea (OSA) subjects.
  
  
  METHODS
  A case-controlled study was performed between February 2013 and January 2014, with 36 (18 OSA and 18 non-OSA) outpatients enrolled in this study. Polysomnographic parameters and results of body fluid were compared between the two groups.
  
  
  RESULTS
  There were no differences in age, weight, and body mass index (BMI) between groups. Compared with the non-OSA group, OSA group had significantly higher neck circumference (NC) and fluid volume shift in the legs. OSA patients had higher left and right leg fluid indices than non-OSA subjects. There were significant correlations between apnoea-hypopnoea index and baseline fluid indices in both legs as well as the reduction in overnight change in both legs fluid volume. The increase in NC was also significantly correlated with the reduction in overnight change in both legs fluid volume, but not with the change in head and neck fluid volume. There were significant correlations between change in NC and increased fluid shifts in head and neck volume.
  
  
  CONCLUSIONS
  OSA patients had a higher baseline fluid content in both legs as compared with non-OSA subjects, which may be the basic factor with regards to fluid shifts in OSA patients. The increase in head and neck fluid shift volume did not directly correlate with the severity of OSA.
authors.affiliation: 1 Department of Respiratory Medicine, 2 Department of Geriatric Medicine, 3 Department of Laboratory Medicine, 4 Department of Cardiothoracic Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China.
authors.forename: Ning
authors.initials: N
authors.lastname: Ding
authors.affiliation: 1 Department of Respiratory Medicine, 2 Department of Geriatric Medicine, 3 Department of Laboratory Medicine, 4 Department of Cardiothoracic Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Lin
authors.affiliation: 1 Department of Respiratory Medicine, 2 Department of Geriatric Medicine, 3 Department of Laboratory Medicine, 4 Department of Cardiothoracic Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China.
authors.forename: Xi-Long
authors.initials: XL
authors.lastname: Zhang
authors.affiliation: 1 Department of Respiratory Medicine, 2 Department of Geriatric Medicine, 3 Department of Laboratory Medicine, 4 Department of Cardiothoracic Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China.
authors.forename: Wen-Xiao
authors.initials: WX
authors.lastname: Ding
authors.affiliation: 1 Department of Respiratory Medicine, 2 Department of Geriatric Medicine, 3 Department of Laboratory Medicine, 4 Department of Cardiothoracic Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China.
authors.forename: Bing
authors.initials: B
authors.lastname: Gu
authors.affiliation: 1 Department of Respiratory Medicine, 2 Department of Geriatric Medicine, 3 Department of Laboratory Medicine, 4 Department of Cardiothoracic Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China.
authors.forename: Bu-Qing
authors.initials: BQ
authors.lastname: Ni
authors.affiliation: 1 Department of Respiratory Medicine, 2 Department of Geriatric Medicine, 3 Department of Laboratory Medicine, 4 Department of Cardiothoracic Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.affiliation: 1 Department of Respiratory Medicine, 2 Department of Geriatric Medicine, 3 Department of Laboratory Medicine, 4 Department of Cardiothoracic Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China.
authors.forename: Shi-Jiang
authors.initials: SJ
authors.lastname: Zhang
authors.affiliation: 1 Department of Respiratory Medicine, 2 Department of Geriatric Medicine, 3 Department of Laboratory Medicine, 4 Department of Cardiothoracic Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Wang
keywords: Obstructive sleep apnea (OSA); body composition analysis; fluid shift