title: Relationship between body fat distribution and upper airway dynamic function during sleep in adolescents.
abstract: BACKGROUND
  The obstructive sleep apnea syndrome (OSAS) is associated with increased visceral adipose tissue (VAT) in adults; however, few studies have evaluated VAT in relation to upper airway function in adolescents. We hypothesized that increased neck circumference (NC) and VAT would be associated with increased upper airway collapsibility.
  
  
  METHODS
  Adolescents (24 obese patients with OSAS, 22 obese control patients, and 29 lean control patients) underwent abdominal magnetic resonance imaging, and measurement of upper airway pressure-flow relationships in the activated and hypotonic upper airway states.
  
  
  RESULTS
  Patients with OSAS had a greater activated slope of the pressure-flow relationship (SPF) than control groups (P < 0.001), whereas hypotonic SPF was greater in both obese groups compared with lean control patients (P = 0.01). NC and VAT were greater in obese control patients and those with OSAS than in lean control patients (P < 0.001), but did not differ between obese patients with OSAS and obese control patients. In lean control patients and those with OSAS, increased NC was associated with increased activated SPF, whereas in obese control patients it was associated with decreased activated SPF (P = 0.03). In contrast, increased NC was associated with increased hypotonic SPF in all groups (P < 0.001). There was no significant effect of VAT on either activated or hypotonic SPF for any of the three groups.
  
  
  CONCLUSIONS
  Increased neck circumference was associated with increased upper airway collapsibility in adolescents in the hypotonic but not activated state. These data suggest that obese adolescents without OSAS, despite a narrowed upper airway from adipose tissue, are protected from developing OSAS by upper airway neuromotor activation. Neither neck circumference nor visceral adipose tissue is useful in predicting upper airway collapsibility in obese adolescents.
authors.affiliation: Pulmonary Division, the First Hospital of Jilin University, Changchun, Jilin, China.
authors.forename: Haibo
authors.initials: H
authors.lastname: Yuan
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Schwab
authors.forename: Christopher
authors.initials: C
authors.lastname: Kim
authors.forename: Jiwei
authors.initials: J
authors.lastname: He
authors.forename: Justine
authors.initials: J
authors.lastname: Shults
authors.forename: Ruth
authors.initials: R
authors.lastname: Bradford
authors.forename: Jingtao
authors.initials: J
authors.lastname: Huang
authors.forename: Carole L
authors.initials: CL
authors.lastname: Marcus
mesh_terms: D000293:Adolescent; D050218:Body Fat Distribution / Q000706:statistics & numerical data; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009333:Neck / Q000033:anatomy & histology; D009765:Obesity / Q000150:complications / Q000473:pathology / Q000503:physiopathology; D017286:Polysomnography; D012143:Respiratory Physiological Phenomena; D012137:Respiratory System / Q000033:anatomy & histology*; D012890:Sleep / Q000502:physiology*; D020181:Sleep Apnea, Obstructive / Q000150:complications / Q000473:pathology / Q000503:physiopathology
keywords: Adipose tissue; pressure-flow relationship
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