Oral Continuous Positive Airway Pressure Research Articles

Oral Continuous Positive Airway Pressure for Sleep Apnea: Effectiveness, Patient Preference, and Adherence

Nasal continuous positive airway pressure (CPAP) is the most definitive medical therapy for obstructive sleep apnea (OSA). Many patients have difficulty tolerating nasal CPAP due to nasal airway problems, mouth leak, and general discomfort from the mask and headgear. These limitations may be overcome by an oral mask (Oracle; Fisher & Paykel Healthcare; Languna Hills, CA) that does not require headgear. We performed a study to compare the Oracle mask to conventional nasal and oronasal masks in the effectiveness of CPAP delivery and patient satisfaction and adherence. Ninety-eight, consecutive CPAP-naïve patients with OSA diagnosed by overnight polysomnography (apnea-hypopnea index [AHI] > 5) were referred for CPAP therapy. All patients were presented with a variety of CPAP masks, including nasal, oronasal, and Oracle, and reasons for mask choice were documented. After 3 weeks of acclimatization to the mask of their choice, patients had a CPAP titration sleep study to determine their optimal CPAP level. Further follow-up was obtained 2 months and 6 months later with a subjective patient assessment of CPAP use and efficacy, mask comfort, and upper airway dryness. Patients were predominantly male (70%), middle aged (50.6 +/- 11.7 years), and moderately obese (body mass index, 32.5 +/- 9.0) with severe OSA (AHI, 40.6 +/- 25.8/h) [mean +/- SD]. Patients were classified into three groups based on their choice of mask: nasal (66%), Oracle (27%), and oronasal (7%). Baseline characteristics did not differ significantly between groups. Optimal CPAP was not significantly different between mask groups (nasal, 7.7 +/- 2.1 cm H(2)O; Oracle, 8.0 +/- 2.0 cm H(2)O; oronasal, 9.7 +/- 3.2 cm H(2)O; p = 0.267). Subjective ratings of adherence, efficacy, and mask comfort were also similar between groups. However, the Oracle group had more complaints of upper airway dryness and "rain-out." The oronasal group had a disproportionately greater number of dropouts from CPAP therapy than the Oracle group (57% vs 19%, p = 0.046). Nine patients changed from the Oracle mask to a nasal mask during the study, whereas no patients changed from their nasal or oronasal masks. The Oracle mask is an efficacious interface for long-term CPAP therapy in patients with OSA. The main limitations of the mask are upper airway dryness and rain-out associated with heated humidification, which may be improved by further technical modifications. Oracle may be more acceptable than oronasal masks for patients who cannot rely exclusively on the nasal airway for CPAP therapy.

A Physiologic Comparison of Nasal and Oral Positive Airway Pressure

The effectiveness of nasal continuous positive airway pressure (CPAP) in treating obstructive sleep apnea (OSA) is based on raising the intramural pressure above a critical collapsing pressure of the oropharyngeal airway. It is currently unclear whether CPAP delivered orally is also capable of raising pressure in the oropharynx above the critical collapse pressure. We tested a novel oral CPAP device to determine whether the pressure-flow relationships are similar to nasal CPAP and whether the device alters these relationships. Patients were selected based on having moderately severe apnea and were randomized to nasal CPAP, nasal CPAP with oral device, or oral CPAP. Johns Hopkins University, The Johns Hopkins Asthma and Allergy Center, Baltimore, MD. Five men and two women with OSA were studied. Individual pressure-flow curves were constructed during the application of nasal or oral CPAP. We found the following: (1) a similar effective pressure eliminated inspiratory flow limitation for the nasal or oral CPAP; (2) as pressure in the nose or mouth was lowered below the effective pressure, a linear pressure-flow curve was obtained and a critical closing pressure was described; (3) similar mean (+/- SD) critical pressures of -0.3 +/- 5.3, 1.7 +/- 4.0, and 0.5 +/- 2.8 cm H(2)O, respectively, occurred for nasal CPAP, nasal CPAP with the oral device in place, and oral CPAP conditions (p > 0.1); and (4) the comparable mean values for upstream resistance were 27.8 +/- 19, 19.1 +/- 8.3, and 26.5 +/- 26.7 cm H(2)O/L/s, respectively, for the above three conditions (p > 0.1). We concluded that comparable upper airway pressure-flow relationships were obtained during oral and nasal breathing. Moreover, effective treatment pressure is obtained when constant pressure is applied through either the nasal or oral route.