A method to evaluate upper airway mechanics following intervention in snorers.

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 METHODS: Retropalatal, retroglossal, and retrohyoid airway segments were evaluated before and after application of an oral appliance (OA) in four snoring subjects. Twelve airway segments were evaluated. Physiological fluctuations during sleep were controlled with variably applied nasal continuous positive pressure (CPAP), benzodiazepam-induced sleep, and obtaining measures at zero flow on the first test breath. Airway area was measured endoscopically.

RESULTS: The methodology identified that following intervention with an OA, maximum retroglossal airway size increased 23.3% +/- 7.5% (P < .05) and retrohyoid size decreased -63.5% +/- 16.0% (P < .05). No changes in retropalatal area (-2.5% +/- 3.0%) or closing pressure were observed. The level of primary obstruction shifted inferiorly in one patient. Airway measures prior to intervention showed small alterations of applied pressure (1 cm H2O) changed 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 control airway collapse and evaluate interventions, such as OA or surgery, for snoring and obstructive sleep apnea syndrome.