title: Upper airway morphology in patients with obstructive sleep apnea syndrome: effects of lateral positioning.
abstract: OBJECTIVE
  The aim of this study was to clarify the interaction of lateral and supine sleeping positions with upper airway morphology in patients with obstructive sleep apnea syndrome (OSAS).
  
  
  METHODS
  Thirty-one patients with OSAS, whose apnea/hypopnea index (AHI: number of episodes of apnea or hypopnea per hour) was over 15, were enrolled in this study. Subjects were divided in two groups according to positional effects on their AHI. In six patients, a lateral posture decreased the AHI by 50% and more (responders); in the remaining 25, lateral positioning decreased the AHI by less than 50% or even increased the AHI (nonresponders). AHI and body mass index (BMI) of the responders tended to be lower and their mean age was younger than those of nonresponders, but these differences were not statistically significant. We compared the upper airway morphology between the responders and the nonresponders regarding the tonsil size, tongue position (modified Mallanpati grade, reflecting the space between the tongue and soft palate) and the width of the fauces and retroglossal space. In addition, we compared nasal resistance between the groups using active rhinomanometry.
  
  
  RESULTS
  The width of the fauces was significantly greater (P=0.041) among the responders than among the nonresponders. However, the other parameters were not consistently different between the two, and these differences were not statistically significant either.
  
  
  CONCLUSIONS
  The distance between the fauces was the sole morphological feature to distinguish the responders and the nonresponders to the positional therapy in patients with OSAS. Lateral positioning during sleep might be a recommended sleep hygiene for OSAS patients with wide fauces.
authors.affiliation: Department of Psychiatry, Nagoya University Graduate School of Medicine, 65 Tsurumai-Cho, Showa-ku, Nagoya 466-8550, Japan.
authors.forename: Taro
authors.initials: T
authors.lastname: Soga
authors.forename: Seiichi
authors.initials: S
authors.lastname: Nakata
authors.forename: Fumihiko
authors.initials: F
authors.lastname: Yasuma
authors.forename: Akiko
authors.initials: A
authors.lastname: Noda
authors.forename: Tatsuki
authors.initials: T
authors.lastname: Sugiura
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yatsuya
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Koike
authors.forename: Norio
authors.initials: N
authors.lastname: Ozaki
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Nakashima
mesh_terms: D004569:Electroencephalography; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009296:Nasal Cavity / Q000503:physiopathology*; D010160:Palate, Soft / Q000502:physiology; D014066:Palatine Tonsil / Q000033:anatomy & histology; D011187:Posture; D025363:Rhinomanometry; D012720:Severity of Illness Index; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis / Q000503:physiopathology*; D014059:Tongue / Q000502:physiology