title: Upper-Airway Collapsibility and Loop Gain Predict the Response to Oral Appliance Therapy in Patients with Obstructive Sleep Apnea.
abstract: Oral appliances (OAs) are commonly used as an alternative treatment to continuous positive airway pressure for patients with obstructive sleep apnea (OSA). However, OAs have variable success at reducing the apnea-hypopnea index (AHI), and predicting responders is challenging. Understanding this variability may lie with the recognition that OSA is a multifactorial disorder and that OAs may affect more than just upper-airway anatomy/collapsibility.
  
  
  
  The objectives of this study were to determine how OA alters AHI and four phenotypic traits (upper-airway anatomy/collapsibility and muscle function, loop gain, and arousal threshold), and baseline predictors of which patients gain the greatest benefit from therapy.
  
  
  
  In a randomized crossover study, 14 patients with OSA attended two sleep studies with and without their OA. Under each condition, AHI and the phenotypic traits were assessed. Multiple linear regression was used to determine independent predictors of the reduction in AHI.
  
  
  
  OA therapy reduced the AHI (30 ± 5 vs. 11 ± 2 events/h; P < 0.05), which was driven by improvements in upper-airway anatomy/collapsibility under passive (1.9 ± 0.7 vs. 4.7 ± 0.6 L/min; P < 0.005) and active conditions (2.4 ± 0.9 vs. 6.2 ± 0.4 L/min; P < 0.001). No changes were seen in muscle function, loop gain, or the arousal threshold. Using multivariate analysis, baseline passive upper-airway collapsibility and loop gain were independent predictors of the reduction in AHI (r2= 0.70; P = 0.001).
  
  
  
  Our findings suggest that OA therapy improves the upper-airway collapsibility under passive and active conditions. Importantly, a greater response to therapy occurred in those patients with a mild anatomic compromise and a lower loop gain.
authors.affiliation: 1 Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham & Women's Hospital and Harvard Medical School, Boston, Massachusetts.|2 Sleep and Circadian Medicine Laboratory, Department of Physiology.|3 School of Psychological Sciences and Monash Institute of Cognitive and Clinical Neurosciences, and.
authors.forename: Bradley A
authors.identifier: 0000-0001-9383-1644
authors.initials: BA
authors.lastname: Edwards
authors.affiliation: 2 Sleep and Circadian Medicine Laboratory, Department of Physiology.
authors.forename: Christopher
authors.initials: C
authors.lastname: Andara
authors.affiliation: 2 Sleep and Circadian Medicine Laboratory, Department of Physiology.
authors.forename: Shane
authors.initials: S
authors.lastname: Landry
authors.affiliation: 1 Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham & Women's Hospital and Harvard Medical School, Boston, Massachusetts.|4 Department of Allergy, Immunology and Respiratory Medicine and Central Clinical School, The Alfred and Monash University, Melbourne, Victoria, Australia.
authors.forename: Scott A
authors.initials: SA
authors.lastname: Sands
authors.affiliation: 6 School of Clinical Sciences, Monash University, Melbourne, Victoria, Australia.|5 Monash Lung and Sleep, Monash Medical Centre, Clayton, Victoria, Australia; and.
authors.forename: Simon A
authors.initials: SA
authors.lastname: Joosten
authors.affiliation: 1 Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham & Women's Hospital and Harvard Medical School, Boston, Massachusetts.|7 Division of Pulmonary and Critical Care Medicine, University of California San Diego, San Diego, California.
authors.forename: Robert L
authors.initials: RL
authors.lastname: Owens
authors.affiliation: 1 Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham & Women's Hospital and Harvard Medical School, Boston, Massachusetts.
authors.forename: David P
authors.initials: DP
authors.lastname: White
authors.affiliation: 6 School of Clinical Sciences, Monash University, Melbourne, Victoria, Australia.|5 Monash Lung and Sleep, Monash Medical Centre, Clayton, Victoria, Australia; and.
authors.forename: Garun S
authors.initials: GS
authors.lastname: Hamilton
authors.affiliation: 1 Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham & Women's Hospital and Harvard Medical School, Boston, Massachusetts.
authors.forename: Andrew
authors.initials: A
authors.lastname: Wellman
mesh_terms: D000402:Airway Obstruction / Q000503:physiopathology*; D000403:Airway Resistance / Q000502:physiology*; D018592:Cross-Over Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009967:Orthodontic Appliances; D010614:Pharynx / Q000503:physiopathology*; D017286:Polysomnography; D020181:Sleep Apnea, Obstructive / Q000503:physiopathology* / Q000628:therapy*; D016896:Treatment Outcome
keywords: obstructive sleep apnea; upper-airway anatomy; ventilation