Nasal Resistive Devices for OSA Treatment
1. Multiple imaging studies (nasopharyngoscopy, fluoroscopy, cephalometric radiography, CT, MRI, echo imaging, computer fluid dynamics) have been done on the upper airway in patients with OSA to evaluate the site of obstruction, its timing in the respiratory cycle, and the response to different therapeutic modalities.
2. Studies have revealed that little airway narrowing occurred during inspiration even in patients with OSA and that the airway narrowed significantly at the end of expiration, especially in patients with OSA.
3. These findings prompted the testing of CPAP alternatives to maintain a positive intraluminal pressure at end-expiration to maintain the airway patency.
4. The Ventus Provent is a new expiratory positive airway pressure (EPAP) nasal device that is a single-use nasal valve inserted into each nostril and sealed with adhesive. The device has negligible inspiratory resistance and a fixed expiratory resistance.
5. Multiple studies of the Ventus Provet EPAP device have shown about a 65% success rate (reduction of AHI by >50% or AHI decrease to <10) with compliance of nearly 90%.
6. EPAP nasal resistive devices show promising results, the mechanism of action has a clear pathophysiologic explanation and its simplicity is appealing.
7. Since EPAP nasal devices have a fixed resistance, they are difficult to tailor to the individual patient and the ability to predict the level of response to the treatment is difficult to predict in advance.
8. Ultimately, the partial response could be solved by using a device with variable adjustable resistance in the sleep laboratory to determine the optimal resistance, and the prescribing an EPAP nasal device with a matching resistance.