Background CPAP is the gold standard treatment for OSA and was conceived to be applied through a nasal interface. This study was designed to determine the acute effects of changing the nasal CPAP ...route to oronasal and oral in upper airway patency during sleep in patients with OSA. We hypothesized that the oronasal route may compromise CPAP’s effectiveness in treating OSA. Methods Eighteen patients (mean ± SD age, 44 ± 9 years; BMI, 33.8 ± 4.7 kg/m2 ; apnea-hypopnea index, 49.0 ± 39.1 events/hour) slept with a customized oronasal mask with nasal and oral sealed compartments connected to a multidirectional valve. Sleep was monitored by using full polysomnography and induced by low doses of midazolam. Nasal CPAP was titrated up to holding pressure. Flow route was acutely changed to the oronasal (n = 18) and oral route (n = 16) during sleep. Retroglossal area was continuously observed by using nasoendoscopy. Results Nasal CPAP (14.8 ± 4.1 cm H2 O) was able to stabilize breathing in all patients. In contrast, CPAP delivered by the oronasal and oral routes promoted obstructive events in 12 (66.7%) and 14 (87.5%) patients, respectively. Compared with stable breathing during the nasal route, there was a significant and progressive reduction in the distance between the epiglottis and tongue base and the retroglossal area when CPAP was delivered by the oronasal and oral routes. Conclusions CPAP delivered through the oronasal route may compromise CPAP’s effectiveness in treating OSA.
