O057 Effects of oral appliance therapy on upper airway collapsibility pre- versus post-treatment

INTRODUCTION: A key predictive mechanism of improvement in obstructive sleep apnoea (OSA) severity with oral appliance therapy (OAT) is a less collapsible upper airway. In this study, we investigate the effects of acute versus longer-term use of OAT on upper airway collapsibility. METHODS: To investigate potential changes in upper airway collapsibility we studied 10 treatment naïve people (2 female) with OSA (AHI=40±31events/h, age=51±11years, BMI=29±4kg/m-2) at baseline and following 4-6 weeks oral appliance therapy acclimatization. The upper airway collapsibility index was measured during wakefulness with/without the oral appliance in place at two time points (pre/post treatment). All participants were instrumented with standard polysomnography equipment, two pressure catheters (one at the level of the choanae, and the other at the epiglottis), a pneumotachograph, sealed nasal mask and a short tubing connected to a breathing circuit to allow rapid delivery of negative pressure ~-11cmH₂O to the mask. RESULTS: The upper airway collapsibility index measured during early inspiration was reduced by 11% (33±19 vs. 22±16%, n=10, p=0.02) with OAT in place in treatment naïve participants. Similarly, following acclimatization, the upper airway collapsibility index also reduced by 7% with OAT in place (25±15 vs. 18±15%, n=9, p=0.03). CONCLUSIONS: While further work is required to determine if long-term OAT independently improves upper airway collapsibility, these data show sustained improvements in upper airway collapsibility with OAT over time and highlight the potential for this approach to help predict OAT treatment outcomes.