title: Utilizing inspiratory airflows during standard polysomnography to assess pharyngeal function in children during sleep.
abstract: OBJECTIVE
  Obstructive sleep apnea (OSA) is the result of pharyngeal obstruction that occurs predominantly during REM in children. Pathophysiologic mechanisms responsible for upper airway obstruction, however, are poorly understood. Thus, we sought to characterize upper airway obstruction in apneic compared to snoring children during sleep. We hypothesized that apneic compared to snoring children would exhibit an increased prevalence and severity of upper airway obstruction, that would be greater in REM compared to non-REM, and would improve following adenotonsillectomy.
  
  
  METHODS
  Apneic children were assessed with routine polysomnography before and after adenotonsillectomy, and compared to snoring children matched for gender, age, and BMI z-score. In addition to traditional scoring metrics, the following were used to characterize upper airway obstruction: maximal inspiratory airflow (%VI max) and percent of time with inspiratory flow-limited breathing (%IFL).
  
  
  RESULTS
  OSA compared to snoring children had similar degrees of upper airway obstruction in non-REM; however, during REM, children with sleep apnea exhibited a higher %IFL (98 ± 2% vs.73 ± 8%, P < 0.01) and lower %VI max (56 ± 6 vs.93 ± 10%, P < 0.01). In children with OSA, CO2 levels were elevated during both wake and sleep. Following adenotonsillectomy, upper airway obstruction improved during REM manifest by decreased %IFL (98 ± 2 to 63 ± 9%, P = 0.04), increased %VI max (56 ± 6 to 95 ± 5%, P = 0.01) and decreased CO2 levels.
  
  
  CONCLUSIONS
  Differences in the prevalence and severity upper airway obstruction suggest impaired compensatory responses during REM in children with OSA, which improved following adenotonsillectomy.
authors.affiliation: Division of Pediatric Pulmonary and Sleep Medicine, University of Utah, Salt Lake City, Utah.
authors.forename: Brian M
authors.initials: BM
authors.lastname: McGinley
authors.affiliation: Johns Hopkins Sleep Disorders Center, Division of Pulmonary and Critical Care Medicine, Johns Hopkins University, Baltimore, Maryland.
authors.forename: Jason P
authors.initials: JP
authors.lastname: Kirkness
authors.affiliation: Johns Hopkins Sleep Disorders Center, Division of Pulmonary and Critical Care Medicine, Johns Hopkins University, Baltimore, Maryland.
authors.forename: Hartmut
authors.initials: H
authors.lastname: Schneider
authors.affiliation: Department of Clinical Neurosciences, Movement Disorders and Human Motor Physiology Laboratory, National Institute of Mental Health & Neurosciences (NIMHANS), Bangalore, India.
authors.forename: Abhishek
authors.initials: A
authors.lastname: Lenka
authors.affiliation: Johns Hopkins Sleep Disorders Center, Division of Pulmonary and Critical Care Medicine, Johns Hopkins University, Baltimore, Maryland.
authors.forename: Philip L
authors.initials: PL
authors.lastname: Smith
authors.affiliation: Johns Hopkins Sleep Disorders Center, Division of Pulmonary and Critical Care Medicine, Johns Hopkins University, Baltimore, Maryland.
authors.forename: Alan R
authors.initials: AR
authors.lastname: Schwartz
mesh_terms: D000233:Adenoidectomy; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008297:Male; D010614:Pharynx / Q000503:physiopathology*; D017286:Polysomnography; D011184:Postoperative Period; D057234:Preoperative Period; D012890:Sleep; D020181:Sleep Apnea, Obstructive / Q000150:complications / Q000503:physiopathology* / Q000601:surgery; D012913:Snoring / Q000209:etiology / Q000503:physiopathology* / Q000601:surgery; D014068:Tonsillectomy; D016896:Treatment Outcome; D014481:United States / Q000453:epidemiology
keywords: adenotonsillectomy; compensatory responses to sleep apnea; obstructive sleep apnea