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 SpO2 (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.

Sleep Stage Coordination of Respiration and Swallowing: A Preliminary Study.

Swallowing is an important physiological response that protects the airway. Although aspiration during sleep may cause aspiration pneumonia, the mechanisms responsible have not yet been elucidated. We evaluated the coordination between respiration and swallowing by infusing water into the pharynx of healthy young adults during each sleep stage. Seven normal subjects participated in the study. During polysomnography recordings, to elicit a swallow we injected distilled water into the pharynx during the awake state and each sleep stage through a nasal catheter. We assessed swallow latency, swallow apnea time, the respiratory phase during a swallow, the number of swallows, and coughing. A total number of 79 swallows were recorded. The median swallow latency was significantly higher in stage 2 (10.05 s) and stage 3 (44.17 s) when compared to awake state (4.99 s). The swallow latency in stage 3 showed a very wide interquartile range. In two subjects, the result was predominantly prolonged compared to the other subjects. There was no significant difference in the swallow apnea time between sleep stages. The presence of inspiration after swallowing, repetitive swallowing, and coughing after swallowing was more frequent during sleep than when awake. This study suggests that the coordination between respiration and swallowing as a defense mechanism against aspiration was impaired during sleep. Our results supported physiologically the fact that healthy adult individuals aspirate pharyngeal secretions during sleep.