title: Body position and breathing abnormalities during sleep: a systematic study.
abstract: BACKGROUND
  Until now, studies about body position and nocturnal breathing abnormalities have been restricted to comparing supine versus lateral positions.
  
  
  OBJECTIVE
  In this retrospective study, we systematically evaluated the effect of body position on nocturnal breathing in 105 patients with a sleep apnea hypopnea syndrome (SAHS).
  
  
  METHODS
  All the patients had an apnea hypopnea index > 10/h, as judged from polysomnography performed in the sleep laboratory. A thoracic sensor allowed to detect nine distinct body positions: supine (S), supine right (SR), right (R), prone right (PR), prone (P), prone left (PL), left (L), supine left (SL) and sitting upward (UP). Respiratory variables (number of obstructive, central and mixed apneas, of hypopneas and of desaturations, all expressed as an index per hour of total sleep time) were evaluated versus the body positions, using the non-parametric Kruskal-Wallis H method. Pairwise comparisons were performed using Mann-Whitney U tests.
  
  
  RESULTS
  Most of the total sleep time (45%) was spent supine. A significant effect of body position was found for all the respiratory variables. Breathing was better in the intermediate SR and SL positions than S, and also better in PR and PL positions than, respectively, R and L. All the respiratory variables gradually improved when gradualling moving from the S to the P position.
  
  
  CONCLUSIONS
  A nine position sensor, able to define intermediate positions in addition to the basic cardinal positions, is useful in the sleep laboratory. Using such a sensor, we found in SAHS patients that nocturnal breathing improves as a continuum from the S to the P position.
authors.affiliation: Department of Pulmonary Medicine, CHU Brabois, Nancy, France. angelica.tiotiu@yahoo.com
authors.forename: Angelica
authors.initials: A
authors.lastname: Tiotiu
authors.forename: Olivier
authors.initials: O
authors.lastname: Mairesse
authors.forename: Guy
authors.initials: G
authors.lastname: Hoffmann
authors.forename: Doina
authors.initials: D
authors.lastname: Todea
authors.forename: André
authors.initials: A
authors.lastname: Noseda
mesh_terms: D000465:Algorithms; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017286:Polysomnography / Q000379:methods; D011187:Posture; D016684:Prone Position; D012189:Retrospective Studies; D020181:Sleep Apnea, Obstructive / Q000503:physiopathology*; D018709:Statistics, Nonparametric; D016683:Supine Position