Dept of Respiratory Medicine, Royal North Shore Hospital, St Leonards, NSW, Australia; Woolcock Institute of Medical Research, University of Sydney, NSW, Australia; and Dept of Respiratory and Sleep Medicine, St George Hospital, University of New South Wales, NSW, Australia.
This study aimed to explore the effect of mandibular advancement splints (MAS) on upper airway anatomy during wakefulness in obstructive sleep apnoea (OSA).Patients commencing treatment of OSA with MAS were recruited. Response to treatment was defined by a 50% or greater reduction in the apnoea-hypopnoea index. Nasopharyngoscopy was performed in the supine position.Nasopharyngoscopy was performed in 18 responders and 17 non-responders. Mandibular advancement caused an increase in the calibre of the velopharynx (+40%+/-10%), with relatively minor changes occurring in the oropharynx and hypopharynx. An increase in cross-sectional area of the velopharynx with mandibular advancement occurred to greater extent in responders than non-responders (+56+/-16% vs +22+/-13%; p<0.05). Upper airway collapse during the Müller manoeuvre, relative to the baseline cross-sectional area, was greater in non-responders than responders in the velopharynx (-94+/-4% vs -69+/-9%; p<0.01) and oropharynx (-37+/-6% vs -16+/-3%; p<0.01). When the Müller manoeuvre was performed with mandibular advancement, airway collapse was greater in non-responders than responders in the velopharynx (-80+/-11% vs +9+/-37%; p<0.001), oropharynx (-36+/-6% vs -20+/-5%; p<0.05) and hypopharynx (-64+/-6% vs -42+/-6%; p<0.05).These results indicate that velopharyngeal calibre is modified by MAS treatment and this may be useful for predicting treatment response.