Introduction: Presently, there is no reliable method to predict mandibular advancement splint (MAS) treatment outcome in OSA patients. We have previously used quantitative measurement of nasopharynoscopic images and found reduced simulated airway collapse (Muller manoeuvre) in MAS treatment responders compared to non-responders. However, to be clinically useful nasopharyngoscopic assessment of the airway response to MAS must be quick and subjectively assessed.

Methods: OSA patients (AHI>10/hr) commencing MAS treatment were recruited. A customised bite block set to 100% maximal protrusion was used to induce MA. A scoring sheet with schematic diagrams was developed to assess: 1) changes in airway diameter with MA during tidal breathing, 2) amount of airway collapse during the Muller manoeuvre at baseline and with MA. Assessments were made at 3 airway levels (velopharynx, oropharynx and hypopharynx). Observations were scored as 1) <50%, >50% increase or no change in airway diameters 2) <50% or >50% collapse during the Muller manoeuvre, as well as pattern of airway wall collapse.

Results: Nasopharynscopy is complete in 23 patients (age 56.52±10.55 years; BMI 25.17±4.72 kgm2; AHI 28.03±14.03 hr-1). During tidal breathing, MA was observed to increase upper airway diameter more frequently in the lateral than anterioposterior dimension in all three airway regions. When the Muller manoeuvre was performed, significant collapse (>50%) was reported in the majority of patients in the velopharynx (87%), oropharynx (74%) and hypopharynx (56%). With MA, significant airway collapse reduced in the velopharynx (26% of patients), oropharynx (31%) and hypopharynx (13%). The pattern of collapse, both without and with MA, was predominantly from the lateral airway walls.

Conclusion: Subjective nasopharyngoscopic assessment of the upper airway with MA showed reduced collapse in all airway regions. Work is ongoing to compare observed patterns of upper airway changes with MA between MAS treatment responders and non-responders.