Obstructive Sleep Apnea Treatment With Epap Nasal Devices: Physiological Principles and Limitations - Obstructive Sleep Apnea Treatment With Epap Nasal Devices: Physiological Principles and Limitations - Open Access Pub

Expiratory Positive airway pressure (EPAP) devices such as prevent have been used for treatment of obstructive sleep apnea without discussing their limitations. In this short review we discuss the physiological limitations of EPAP devices during inspiration and during expiration. During spontaneous breathing, when EPAP is excessive, the patient would have difficulty breathing in because lung compliance decreases at higher volumes. Furthermore excessive EPAP could lead to progressive trapping of air in the lungs. An ideal EPAP device should allow the patient to adjust the resistance to a comfortable level that would provide EPAP without a progressive buildup in pressure, without compromising tidal volume, without causing CO2 retention, and without disturbing sleep. The use of EPAP devices with adjustable resistance is essential for best results in treatment of obstructive sleep apnea and snoring. DOI10.14302/issn.2574-4518.jsdr-16-1333 The preferred therapy for obstructive sleep apnea (OSA) is continuous positive airway pressure (CPAP) 1. A new expiratory resistance device called prevent was introduced by Ventus Medical in 2008 (Belmont, CA) as an option for OSA treatment. prevent consisted of a miniature two-way valve that fits against the opening of the nostril and is fixed in place with adhesive material to provide a seal 2, 3. The valve allows a patient to breathe in with minimal resistance and breathe out through a narrow hole with high resistance, thus generating an expiratory positive airway pressure (EPAP). This device simulated experiments that were published in 1983 by Mahadevia et al 4 concluding that increased pressure during expiration is in itself sufficient to treat OSA. prevent was cleared by the Food and Drug Administration (FDA) as an EPAP device for treatment of OSA with all severities. The effectiveness and safety of prevent was validated through several published clinical trials 2, 3, 5, 6, 7 demonstrating significant reductions in apnea-hypopnea index, oxygen desaturation, and daytime sleepiness. Wu et al 8 and Riaz et al 9 reviewed, in detail, most of the studies that used prevent, and the reader is referred to such reviews. Others have also reviewed the literature and, in general, gave favorable opinions about use of prevent as an EPAP device for treatment of OSA 8, 9, 10, 11, 12. It remains unclear why prevent is not effective in some patients 12. prevent was usually more effective in patients with mild to moderate OSA than in patients with severe OSA 5. One study attempted to identify if other factors determine which patient is