Nasal Versus Oronasal Mask in Continuous Positive Airway Pressure (CPAP) Treatment of Patients Affected by Obstructive Sleep Apnea Syndrome (OSAS).

Continuous positive airway pressure (CPAP) is considered the gold standard treatment for patients with moderate to severe obstructive sleep apnea (OSA). Nasal and oronasal masks are often used interchangeably and are generally believed to be equally effective; the choice of interface for OSA therapy remains largely based on clinical judgement and patients preference. However, there is increasing evidence that CPAP delivered by an oronasal mask may be less effective, requires more pressure and are worse tolerated than nasal mask. Patients with OSA on oronasal mask are also less adherent to CPAP. Some authors have suggested that in some subjects, the CPAP was not effective when an oronasal mask was used. Moreover when pressures are increased to overcome the obstruction, a paradoxical obstruction may take place. Specific mechanisms explaining upper-airway obstruction events remain unclear and it is not known how many patients exhibit this behavior. This observational retrospective study is designed to compare a group of patients with obstructive sleep apnea with persistent obstructive events using oronasal masks during CPAP, that were fully recovered with the shift to nasal one with the same or also lower pressure, versus a control group of patients who did not report obstruction with oronasal masks. Aim of the study was to find differences in term of clinical, anatomical and physiological characteristics between these two groups.