title: Factors influencing sleep time with oxygen saturation below 90% in sleep-disordered breathing.
abstract: OBJECTIVE
  To determine factors influencing sleep time with oxygen saturation below 90% (ST₉₀) in a population referred to a tertiary sleep center for assessment of possible sleep-disordered breathing (SDB).
  
  
  METHODS
  Retrospective review of demographic and polysomnographic data of 731 consecutive patients with suspected SDB.
  
  
  METHODS
  Bivariate correlation analyses were performed, and Spearman rho coefficients were calculated. Variables with a marginal association with ST₉₀ (P < .05) in the bivariate analysis were included into the multiple regression analysis.
  
  
  RESULTS
  The distributions of SDB were as follows: normal/simple snoring, 18.2%; mild obstructive sleep apnea (OSA), 25.6%; moderate OSA, 17.4%; and severe OSA, 38.9%. The univariate analysis revealed a significant correlation between ST₉₀ and age (r = 0.204), body mass index (BMI) (r = 0.440), arousal index (r = 0.754), apnea-hypopnea index (AHI) (r = 0.761), mean oxygen saturation (SaO₂) (r = -0.506), and mean O₂ desaturation (r = 0.858) (P < .001 for all parameters). In multiple regression analysis, age (P < .001), BMI (P = .040), male gender (P = .001), AHI (P < .001), mean SaO₂ (P < .001), and mean O₂ desaturation (P < .001) were found to be independent parameters influencing ST₉₀. Furthermore, these parameters explained a significant proportion of variance in ST₉₀ (R(2)  = 0.794, F (6, 729) = 464.65, P < .001). Although there was a strong correlation between AHI and ST₉₀ (r = 0.76, P < .001), a large variation of ST₉₀ values was observed, especially within the severe OSA group.
  
  
  CONCLUSIONS
  The study results provide supporting evidence that patients with similar AHI may have quite different values of ST₉₀, and thereby hypoxia. The stratification of patients with OSA according to AHI combined with ST₉₀ may allow better identification of prognostic information.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Akdeniz University School of Medicine, Antalya, Turkey.
authors.forename: Asli
authors.initials: A
authors.lastname: Bostanci
authors.forename: Murat
authors.initials: M
authors.lastname: Turhan
authors.forename: Selen
authors.initials: S
authors.lastname: Bozkurt
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D000704:Analysis of Variance; D001784:Blood Gas Analysis; D015992:Body Mass Index; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood*; D010101:Oxygen Consumption / Q000502:physiology; D017286:Polysomnography; D012044:Regression Analysis; D012189:Retrospective Studies; D012307:Risk Factors; D012720:Severity of Illness Index; D017678:Sex Distribution; D012890:Sleep / Q000502:physiology*; D012891:Sleep Apnea Syndromes / Q000175:diagnosis* / Q000453:epidemiology*; D018709:Statistics, Nonparametric; D062606:Tertiary Care Centers; D013997:Time Factors; D055815:Young Adult
chemical_list: D010100:Oxygen
keywords: Obstructive sleep apnea; hypoxia; sleep time with oxygen saturation below 90%