title: Upper Airway Reflexes are Preserved During Dexmedetomidine Sedation in Children With Down Syndrome and Obstructive Sleep Apnea.
abstract: OBJECTIVE
  The assessment of pharyngeal collapsibility is difficult to perform in children under normal sleep. An alternative is to perform the assessment under an anesthetic, such as dexmedetomidine (DEX), that induces non-rapid eye movement (NREM) sleep. The objectives of this study were to compare critical closing airway pressure (Pcrit) obtained during natural sleep to that obtained under DEX in patients with Down syndrome (DS) and persistent obstructive sleep apnea (OSA) and determine whether Pcrit measured under sedation predicts the severity of OSA.
  
  
  METHODS
  The passive and active Pcrit, which represent airway passive mechanical properties and active dynamic responses to airway obstruction, respectively, were measured. Upper airway reflex activity was estimated by calculating the difference between active and passive Pcrit. Subjects underwent overnight polysomnography during which Pcrit was measured during normal sleep. Pcrit was also measured during DEX sedation at a dose of 2 μg/kg/h.
  
  
  RESULTS
  The study included 50 patients with median age of 11.4 years (interquartile range: 7.0-13.9) and median body mass index of 23.0 kg/m2(interquartile range: 18.4-29.1), 66% male and 80% Caucasian. Passive Pcrit was significantly higher than active Pcrit when measured during normal sleep and DEX-induced sleep. There was a positive association between apnea-hypopnea index and passive Pcrit (Spearman r = 0.53,P= .0001) and active Pcrit (r = 0.55,P= .0002) under DEX-induced sleep. There were no significant differences between the Pcrit measurements during natural sleep and during DEX sedation.
  
  
  CONCLUSIONS
  Patients with OSA can compensate for airway obstruction under DEX-induced sleep. The close association between Pcrit and apnea-hypopnea index suggests that airway responses with DEX sedation parallel those seen during natural sleep.
  
  
  BACKGROUND
  ClinicalTrials.gov identifier: NCT01902407.
authors.affiliation: Department of Anesthesiology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Mahmoud
authors.affiliation: Division of Otolaryngology - Head and Neck Surgery, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio.|Division of Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio.
authors.forename: Stacey L
authors.initials: SL
authors.lastname: Ishman
authors.affiliation: Division of Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio.
authors.forename: Keith
authors.initials: K
authors.lastname: McConnell
authors.affiliation: Department of Radiology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio.
authors.forename: Robert
authors.initials: R
authors.lastname: Fleck
authors.affiliation: Division of Otolaryngology - Head and Neck Surgery, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio.
authors.forename: Sally
authors.initials: S
authors.lastname: Shott
authors.affiliation: Division of Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio.
authors.forename: Goutham
authors.initials: G
authors.lastname: Mylavarapu
authors.affiliation: Division of Otolaryngology - Head and Neck Surgery, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio.|Department of Aerospace Engineering and Engineering Mechanics, University of Cincinnati, Cincinnati, Ohio.
authors.forename: Ephraim
authors.initials: E
authors.lastname: Gutmark
authors.affiliation: Division of Biostatistics and Epidemiology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio.
authors.forename: Yuanshu
authors.initials: Y
authors.lastname: Zou
authors.affiliation: Division of Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio.|Division of Biostatistics and Epidemiology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio.
authors.forename: Rhonda
authors.initials: R
authors.lastname: Szczesniak
authors.affiliation: Division of Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio.
authors.forename: Raouf S
authors.initials: RS
authors.lastname: Amin
mesh_terms: D000293:Adolescent; D002648:Child; D020927:Dexmedetomidine; D004314:Down Syndrome / Q000150:complications*; D005260:Female; D006801:Humans; D006993:Hypnotics and Sedatives; D008297:Male; D010614:Pharynx / Q000187:drug effects* / Q000502:physiology; D017286:Polysomnography; D012720:Severity of Illness Index; D020181:Sleep Apnea, Obstructive / Q000150:complications*
chemical_list: D006993:Hypnotics and Sedatives; D020927:Dexmedetomidine
keywords: airway collapsibility; critical closing pressure; dexmedetomidine; sedation