RESUMO
OBJECTIVE: Due to the complexity of obstructive sleep apnea syndrome (OSAS), engaging patients in the right treatment poses a constant challenge. A novel oral pressure therapy device, the intermittent negative air pressure Sleep Therapy System (iNAP), has proven to ameliorate respiratory events for OSAS patients. However, the mode of action and the characteristics of its responders are not yet fully understood. Therefore, we have first disclosed the mechanism and provided systemic models to predict the treatment response. METHODS: Series of imaging studies were carried out to differentiate the anatomical features of iNAP responders versus non-responders. Compatible electroencephalography was used to evaluate sleep status during magnetic resonance imaging (MRI) assessments. RESULTS: The upper airway volume was statistically widened under the iNAP treatment while patients were naturally asleep (p < 0.05). Negative predictors included several parameters related to oral-tissue redundancy, enlarged middle pharyngeal space, and longer distance of hyoidale to mandibular plane. Positive predictors included larger angulation of sella-articulate-gonion, longer distance of anterior nasal spine to posterior nasal spine, and elongated tongue, which could correspond to the fact that the iNAP had a greater ability to widen the retropalatal region. Furthermore, algorithms developed by these predictors were built to predict treatment response. CONCLUSIONS: We were able to confirm the effect of the iNAP in widening the upper airway. Anatomic features that can be visually observed or obtained through X-ray films, accompanied with the resulting algorithms, were provided to facilitate physicians' ability to predict patients' treatment response to the iNAP with greater sensitivity and efficiency.