title: Association of sleep time in supine position with apnea-hypopnea index as evidenced by successive polysomnography.
abstract: OBJECTIVE
  The purpose of this study is to evaluate the impact of body position during sleep on apnea-hypopnea index (AHI) and night-to-night variability in polysomnography (PSG) parameters.
  
  
  METHODS
  Totally, 30 patients with obstructive sleep apnea syndrome (OSAS) were assessed prospectively with successive PSGs performed. The patients were categorized as increased (group A), decreased (group B), and unchanged (group C) AHI between the first and second PSG evaluations performed at least 1-week interval.
  
  
  RESULTS
  The mean AHI values were significantly higher in the second night (p = 0.02). A change in AHI was found in almost 85 % of the patients between two successive measurements. According to multivariate and correlation analyses and differences in total AHI in supine position (r = 0.897), it was found that the influence of the supine position was the primary factor contributing to the night-to-night variability. Supine AHI, non-supine AHI, and non-supine time findings did not add any significance on total AHI.
  
  
  CONCLUSIONS
  The variability observed in the AHI seems related to amount of sleeping time spent in supine position, suggesting that mean AHI alone is not that reliable in the accurate diagnosis of OSAS severity. A thorough evaluation of AHI in supine and non-supine positions is needed in order to understand better the severity of OSAS.
authors: Department of Otorhinolaryngology, Head and Neck Surgery, Ataturk Training and Research Hospital, Ankara, Turkey.
authors: Gokhan
authors: G
authors: Yalciner
authors: Department of Otorhinolaryngology, Head and Neck Surgery, Yıldırım Beyazıt University School of Medicine, Ankara, Turkey.
authors: Mehmet Ali
authors: MA
authors: Babademez
authors: Department of Otorhinolaryngology, Head and Neck Surgery, Bitlis Tatvan State Hospital, Tatvan, Bitlis, Turkey. drfatihgul@gmail.com.
authors: Fatih
authors: http://orcid.org/0000-0001-7992-0974
authors: F
authors: Gul
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D011187:Posture; D011446:Prospective Studies; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis* / Q000628:therapy*; D012913:Snoring / Q000175:diagnosis / Q000628:therapy; D013223:Statistics as Topic; D016683:Supine Position; D013997:Time Factors
keywords: Apnea-hypopnea index; Polysomnography; Sleep apnea; Sleep position; Supin time