A METHOD TO EVALUATE UPPER AIRWAY MECHANICS FOLLOWING INTERVENTION INSNORERS

Purpose: To describe a method that measures multisegment upper airway changes following intervention for snoring and obstructive apnea that controls for physiological fluctuations during sleep. Patients and Met hods: Retropalatal, retroglossal, and retrohyoid airway segments were evaluated before and after application of an oral appliance (OA) in fo ur snoring subjects. Twelve airway segments were evaluated. Physiologi cal fluctuations during sleep were controlled with variably applied na sal continuous positive applied pressure (CPAP), benzodiazepam-induced sleep, and obtaining measures at zero flow on the first test breath. Airway area was measured endoscopically. Results: The methodology iden tified that following intervention with an OA, maximum retroglossal ai rway size increased 23.3% +/- 7.5% (P <.05) and retrohyoid size decrea sed -63.5% +/- 16.0% (P <.05). No changes in retropalatal area (-2.5% +/- 3.0%) or closing pressure were observed. The level of primary obst ruction shifted inferiorly in one patient. Airway measures prior to in tervention showed small alterations of applied pressure (1 cm H2O) cha nged retropalatal and retroglossal area an average of 10% +/- 0.9%/cm H2O. Conclusion: The mechanical effects of limited airway intervention can be measured with a hypotonic, pressure-controlled methodology. At small airway areas, the airway is highly collapsible and airway size fluctuates. Small changes in applied or physiological forces may alter the airway as significantly as the effects of the intervention being evaluated. The hypotonic upper airway method provides a method to cont rol airway collapse and evaluate interventions, such as OA or surgery, for snoring and obstructive sleep apnea syndrome. Copyright (C) 1997 by W.B. Saunders Company.