title: Vibration signals of snoring as a simple severity predictor for obstructive sleep apnea.
abstract: OBJECTIVE
  Polysomnography (PSG), which involves simultaneous monitoring of various physiological monitors, is the current comprehensive tool for diagnosing obstructive sleep apnea (OSA). We aimed at validating vibrating signals of snoring as a single physiological parameter for screening and evaluating severity of OSA.
  
  
  METHODS
  Totally, 111 subjects from the sleep center of a tertiary referral center were categorized into four groups according to the apnea hypopnea index (AHI) obtained from PSG: simple snoring group (5 > AHI, healthy subjects, n = 11), mild OSA group (5 ≤ AHI < 15, n = 11), moderate OSA group (15 ≤ AHI < 30, n = 30) and severe OSA group (AHI ≥ 30, n = 59). Anthropometric parameters and sleep efficiency of all subjects were compared. Frequencies of amplitude changes of vibrating signals on anterior neck during sleep were analyzed to acquire a snoring burst index (SBI) using a novel algorithm. Data were compared with AHI and index of arterial oxygen saturation (Δ Index).
  
  
  RESULTS
  There were no significant differences in age and sleep efficiency among all groups. Bland-Altman analysis showed better agreement between SBI and AHI (r = 0.906, P < 0.001) than Δ Index and AHI (r = 0.859, P < 0.001). Additionally, receiver operating characteristic (ROC) showed substantially stronger sensitivity and specificity of SBI in distinguishing between patients with moderate and severe OSA compared with Δ Index (sensitivity: 81.4% vs 66.4%; specificity: 96.7% vs 86.7%, for SBI and Δ Index, respectively).
  
  
  CONCLUSIONS
  SBI may serve as a portable tool for screening patients and assessing OSA severity in a non-hospital setting.
authors.affiliation: Department of Electrical Engineering, National Dong Hwa University, Hualien, Taiwan.
authors.forename: Hsien-Tsai
authors.initials: HT
authors.lastname: Wu
authors.affiliation: Department of Electrical Engineering, National Dong Hwa University, Hualien, Taiwan.
authors.forename: Wen-Yao
authors.initials: WY
authors.lastname: Pan
authors.affiliation: Department of Neurology, Buddhist Tzu Chi General Hospital and Buddhist Tzu Chi University, Hualien, Taiwan.
authors.forename: An-Bang
authors.initials: AB
authors.lastname: Liu
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan.
authors.forename: Mao-Chang
authors.initials: MC
authors.lastname: Su
authors.affiliation: Department of Electrical Engineering, National Dong Hwa University, Hualien, Taiwan.
authors.forename: Hong-Ruei
authors.initials: HR
authors.lastname: Chen
authors.affiliation: Department of Emergency Medicine, E-Da Hospital, I-Shou University, Kaohsiung, Taiwan.
authors.forename: I-Ting
authors.initials: IT
authors.lastname: Tsai
authors.affiliation: Sleep Center, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan.
authors.forename: Meng-Chih
authors.initials: MC
authors.lastname: Lin
authors.affiliation: Department of Emergency Medicine, E-Da Hospital, I-Shou University, Kaohsiung, Taiwan.
authors.forename: Cheuk-Kwan
authors.initials: CK
authors.lastname: Sun
mesh_terms: D000328:Adult; D000465:Algorithms; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017286:Polysomnography / Q000379:methods*; D012372:ROC Curve; D012680:Sensitivity and Specificity; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis* / Q000503:physiopathology*; D012913:Snoring / Q000503:physiopathology*; D014732:Vibration
keywords: apnea hypopnea index; arterial oxygen saturation; obstructive sleep apnea; polysomnography; snoring burst index