title: Airway Resistance in Children with Obstructive Sleep Apnea Syndrome.
abstract: OBJECTIVE
  Enlarged tonsils and adenoids, the main cause of obstructive sleep apnea syndrome (OSAS) in children, results in upper airway (UA) loading. This contributes to the imbalance between structural and neuromotor factors ultimately leading to UA collapse during sleep. However, it is unknown whether this UA loading can cause elevated airway resistance (AR) during wakefulness. We hypothesized that children with OSAS have elevated AR compared to controls and that this improves after OSAS treatment.
  
  
  METHODS
  Case control study performed at an academic hospital. Children with OSAS and nonsnoring healthy controls underwent baseline polysomnography and spirometry, and AR measurement by body plethysmography while breathing via an orofacial mask. Children with OSAS repeated the previously mentioned tests after adenotonsillectomy.
  
  
  RESULTS
  31 OSAS participants (mean age ± SD = 9.7 ± 3.0 y, obstructive apnea-hypopnea index (OAHI) median [range] = 14.9 [2-58.7] events/h, body mass index [BMI] z = 1.5 ± 1) and 31 controls (age = 10.5 ± 2.5 y, P = 0.24; OAHI = 0.4 [0-1.4], P < 0.001; BMI z = 0.9 ± 1, P = 0.01) were tested. OSAS AR at baseline was 3.9 [1.5-10.3] cmH2O/L/sec and controls 2.8 [1.4 - 6.2] (P = 0.027). Both groups had similar spirometry results. 20 patients with OSAS were tested 6.4 ± 6.6 mo after adenotonsillectomy. OAHI decreased from 15.2 [2.1-58.7] to 0.5 [0 - 5.1] events/h postoperatively (P < 0.001), and AR decreased from 4.3 [1.5 - 10.3] to 2.8 [1.7 - 4.7] cmH2O/L/sec (P = 0.009).
  
  
  CONCLUSIONS
  Children with OSAS have elevated AR that decreases after treatment. This is likely because of upper airway loading secondary to adenotonsillar hypertrophy and may contribute to the increased frequency of respiratory diseases in untreated children with OSAS.
authors.affiliation: Sleep Center, Division of Pulmonary Medicine, The Children's Hospital of Philadelphia, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA.
authors.forename: Ignacio E
authors.initials: IE
authors.lastname: Tapia
authors.affiliation: Sleep Center, Division of Pulmonary Medicine, The Children's Hospital of Philadelphia, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA.
authors.forename: Carole L
authors.initials: CL
authors.lastname: Marcus
authors.affiliation: Division of Pulmonary Medicine, The Children's Hospital of Philadelphia, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA.
authors.forename: Joseph M
authors.initials: JM
authors.lastname: McDonough
authors.affiliation: Biostatistics Core, Clinical and Translational Research Center, Children's Hospital of Philadelphia. Philadelphia, PA.
authors.forename: Ji Young
authors.initials: JY
authors.lastname: Kim
authors.affiliation: Sleep Center, Division of Pulmonary Medicine, The Children's Hospital of Philadelphia, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA.
authors.forename: Mary Anne
authors.initials: MA
authors.lastname: Cornaglia
authors.affiliation: Biostatistics and Epidemiology, University of Pennsylvania, Philadelphia, PA.
authors.forename: Rui
authors.initials: R
authors.lastname: Xiao
authors.affiliation: Division of Pulmonary Medicine, The Children's Hospital of Philadelphia, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA.
authors.forename: Julian L
authors.initials: JL
authors.lastname: Allen
mesh_terms: D000233:Adenoidectomy; D000234:Adenoids / Q000601:surgery; D000293:Adolescent; D000403:Airway Resistance; D015992:Body Mass Index; D016022:Case-Control Studies; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D014066:Palatine Tonsil / Q000601:surgery; D010991:Plethysmography; D017286:Polysomnography; D012119:Respiration; D012137:Respiratory System / Q000503:physiopathology; D012890:Sleep; D020181:Sleep Apnea, Obstructive / Q000503:physiopathology*; D013147:Spirometry; D014068:Tonsillectomy; D014851:Wakefulness
keywords: OSAS; airway resistance; children