The efficacy of nasal airway stent (Nastent) on obstructive sleep apnoea and prediction of treatment outcomes

Background Obstructive sleep apnoea (OSA) is characterised by recurrent episodes of partial or complete upper airway collapse during sleep and is highly prevalent in the general population. The nasopharyngeal airway stent (Nastent) is a specifically designed, preformed silicone tube that intends to maintain the upper airway patency during sleep and reduce snoring and sleep apnoea. Objective(s) The purpose of this study was to determine the efficacy of Nastent treatment and examine predictors for Nastent treatment outcomes in patients with OSA. Methods Consecutive thirty patients were enrolled in this study. Cephalometric radiographs were obtained to analyse the pharyngeal and craniofacial morphology. Before and after Nastent treatment, we evaluated OSA using a portable sleep study. Results Twenty-nine subjects completed this study. There were significant decreases in the respiratory event index (REI) (22.4 +/- 14.1 to 15.7 +/- 10.4, P < 0.01) and a significant increase in the lowest SpO(2) (81.9 +/- 7.5 to 86.6 +/- 4.8, P < 0.01) by Nastent treatment. Subjects were divided into responders and non-responders based on reduction in REI of >50% compared with baseline REI. We evaluated the ratio of inferior airway width and middle airway width (IAW/MAW) on cephalograms as the index of the narrowest airway site. The IAW/MAW was significantly higher in responders than in non-responders (1.4 +/- 0.9 vs 0.9 +/- 0.4, P < 0.01) and predicted treatment responders with high accuracy (sensitivity: 90.9%, specificity: 88.9%, when IAW/MAW was set at 1.10). Conclusions The Nastent device improved OSA, and a narrower velopharynx than hypopharynx predicted treatment response with a good sensitivity and specificity.