title: Upper airway collapsibility is associated with obesity and hyoid position.
abstract: OBJECTIVE
  Upper airway anatomy plays a major role in obstructive sleep apnea (OSA) pathogenesis. An inferiorly displaced hyoid as measured by the mandibular plane to hyoid distance (MPH) has been consistently associated with OSA. The hyoid is also a common landmark for pharyngeal length, upper airway volume, and tongue base. Tongue dimensions, pharyngeal length, and obesity are associated with OSA severity, although the link between these anatomical variables and pharyngeal collapsibility is less well known. We hypothesized that obesity as measured by body mass index (BMI), neck and waist circumferences, and variables associated with hyoid position (pharyngeal length, upper airway volume, and tongue dimensions) would be associated with passive pharyngeal critical closing pressure (Pcrit).
  
  
  METHODS
  Cross-sectional.
  
  
  METHODS
  Academic hospital.
  
  
  METHODS
  34 Japanese-Brazilian males age 21 to 70 y.
  
  
  METHODS
  N/A.
  
  
  RESULTS
  We performed computed tomography scans of the upper airway, overnight polysomnography, and Pcrit measurements in all subjects. On average, subjects were overweight (BMI = 28 ± 4 kg/m(2)) and OSA was moderately severe (apnea-hypopnea index = 29 [13-51], range 1-90 events/h). Factor analysis identified two factors among the studied variables: obesity (extracted from BMI, neck and waist circumferences) and hyoid position (MPH, pharyngeal length, tongue length, tongue volume, and upper airway volume). Both obesity and hyoid position correlated with Pcrit (r = 0.470 and 0.630, respectively) (P < 0.01). In addition, tongue volume, tongue length, pharyngeal length, and MPH correlated with waist and neck circumferences (P < 0.05).
  
  
  CONCLUSIONS
  Pharyngeal critical closing pressure is associated with obesity and hyoid position. Tongue dimensions, pharyngeal length, and the mandibular plane to hyoid distance are associated with obesity variables. These findings provide novel insight into the potential factors mediating upper airway collapse in obstructive sleep apnea.
authors.affiliation: Pulmonary Division, Heart Institute (InCor), Hospital das Clínicas, University of São Paulo School of Medicine, São Paulo, Brazil and Division of Sleep and Circadian Disorders, Brigham and Women's Hospital, Harvard University, Boston, MA.
authors.forename: Pedro R
authors.initials: PR
authors.lastname: Genta
authors.affiliation: Pulmonary Division, Heart Institute (InCor), Hospital das Clínicas, University of São Paulo School of Medicine, São Paulo, Brazil.
authors.forename: Fabiola
authors.initials: F
authors.lastname: Schorr
authors.affiliation: Neuroscience Research Australia (NeuRA) and the School of Medical Sciences, University of New South Wales, Sydney, Australia.
authors.forename: Danny J
authors.initials: DJ
authors.lastname: Eckert
authors.affiliation: Radiology Institute (InRad), Hospital das Clínicas, University of São Paulo School of Medicine, São Paulo, Brazil.
authors.forename: Eloisa
authors.initials: E
authors.lastname: Gebrim
authors.affiliation: Pulmonary Division, Heart Institute (InCor), Hospital das Clínicas, University of São Paulo School of Medicine, São Paulo, Brazil.
authors.forename: Fabiane
authors.initials: F
authors.lastname: Kayamori
authors.affiliation: Biomedical Engineering Laboratory, University of São Paulo, São Paulo, Brazil.
authors.forename: Henrique T
authors.initials: HT
authors.lastname: Moriya
authors.affiliation: Division of Sleep and Circadian Disorders, Brigham and Women's Hospital, Harvard University, Boston, MA and Pulmonary and Critical Care Medicine, University of California San Diego, La Jolla, CA.
authors.forename: Atul
authors.initials: A
authors.lastname: Malhotra
authors.affiliation: Pulmonary Division, Heart Institute (InCor), Hospital das Clínicas, University of São Paulo School of Medicine, São Paulo, Brazil.
authors.forename: Geraldo
authors.initials: G
authors.lastname: Lorenzi-Filho
mesh_terms: D000328:Adult; D000368:Aged; D044466:Asian People; D015992:Body Mass Index; D001938:Brazil; D003430:Cross-Sectional Studies; D006801:Humans; D006928:Hyoid Bone / Q000033:anatomy & histology* / Q000503:physiopathology; D007564:Japan / Q000208:ethnology; D008297:Male; D008875:Middle Aged; D009333:Neck / Q000033:anatomy & histology / Q000503:physiopathology; D009765:Obesity / Q000150:complications* / Q000503:physiopathology; D010614:Pharynx / Q000033:anatomy & histology* / Q000503:physiopathology*; D017286:Polysomnography; D020181:Sleep Apnea, Obstructive / Q000150:complications* / Q000503:physiopathology*; D014059:Tongue / Q000033:anatomy & histology / Q000503:physiopathology; D055815:Young Adult
keywords: computed tomography; lung; obstructive sleep apnea; pathophysiology; pharynx