Impact of Exclusive Mouth Route and Lateral Position on the Efficacy of Oronasal CPAP to Treat OSA in Patients With OSA Adapted to Oronasal Mask.

Background: Oronasal masks are used widely for treating OSA with CPAP. However, oronasal CPAP is associated with lower effectiveness and lower adherence than nasal CPAP.

Research Question: What is the impact of oral route and lateral position in patients well adapted to oronasal CPAP? Can these patients be switched to nasal CPAP?

Study Design And Methods: Patients with OSA receiving oronasal CPAP underwent two CPAP polysomnography titrations in random order using an oronasal mask with two independent sealed compartments connected to two separate pneumotachographs. One study was performed with the nasal and oral compartments opened and the other study was performed with only the oral compartment opened. CPAP titration was carried out in the supine and lateral positions. Finally, the patients were offered a nasal mask. A third polysomnography test was performed using nasal CPAP.

Results: Twenty patients with OSA (baseline apnea-hypopnea index [AHI], 52 ± 21 events/h) adapted to oronasal CPAP were studied. Most patients (75%) were oronasal breathers with optimal CPAP. Oral CPAP was less effective to treat OSA than oronasal CPAP, evidenced by a higher residual AHI (median, 2 [interquartile range (IQR), 1-6.0] vs 12.5 [IQR, 1.8-28.3); P = .003), despite a significantly higher CPAP level (median, 10 cm HO [IQR, 9-10 cm HO] vs 11 cm HO [IQR, 10-12 cm HO]; P = .003). The residual AHI was significantly lower in the lateral position for both oronasal and oral CPAP. Finally, patients (75%) agreed to change and preferred to continue using a nasal mask, which resulted in lower CPAP and better OSA control.

Interpretation: Our results indicate that the effectiveness of oronasal CPAP to abolish OSA is decreased significantly when patients are required to breathe exclusively through the mouth. Oronasal CPAP efficacy is significantly better in the lateral position. The transition to nasal mask results in higher CPAP effectiveness to treat OSA.

Clinical Trial Registry: ClinicalTrials.gov; No.: NCT05272761; URL: www.

Clinicaltrials: gov.