By Marta Kaminska, MD, MSc; David Zielinski, MD; and Veronique Adam, RRT

The success of positive airway pressure (PAP) therapy, whether continuous positive airway pressure (CPAP) or noninvasive ventilation (NIV) via a bilevel pressure (BPAP) device or a ventilator, largely hinges on the use of an appropriately fitted mask. The interface is crucial for acceptance, comfort, and effectiveness of PAP. Therefore, individualized mask selection and shared decision-making are necessary.

Nasal vs. oronasal (“full face”) options

The initial description of CPAP involved nasal application of pressure to prevent pharyngeal airway collapse. In original physiologic studies, pressure applied at the nose and mouth did not restore airway patency. This was thought to be due to pressure applied at the mouth pushing tongue and soft palate posteriorly, counteracting nasal pressure, which pushes the tongue and soft palate anteriorly.1

Subsequent studies showed oronasal masks could be effective. However, studies also found that in some individuals, oronasal masks are not as effective as nasal masks, leading to higher residual apnea-hypopnea index (AHI) or requiring higher pressures. Nasal masks have been associated with higher satisfaction, better adherence, and greater improvement in sleepiness compared with oronasal masks.

Although oronasal masks can help control mouth leak, they are associated with higher overall leak, lower comfort, and lower adherence. They are also related to higher aspiration risk and impaired ability to communicate, which are important issues for individuals requiring assistance, such as patients with neuromuscular disorders.

In practice, it is commonplace for patients to be offered an oronasal mask when they mention breathing through the mouth at night. However, this may result from obstructive sleep apnea (OSA), with reflex mouth opening when breathing becomes obstructed. If a patient is breathing freely through the nose in the daytime, PAP delivered via a nasal mask will generally correct upper airway obstruction and prevent mouth opening. If mouth opening remains an issue, and pressure is appropriately titrated, a chinstrap could be added (or mouth tape per emerging evidence), as outcomes are likely to be better than with an oronasal mask in many cases. Oronasal masks should largely be reserved for individuals with severe nasal obstruction or anatomical constraints preventing nasal breathing.1 Patients with neuromuscular disease who have marked jaw drooping due to reduced muscle tone may also need an oronasal mask for comfort and to control mouth leak. Given potential drawbacks, a risk-benefit discussion is needed.

Other considerations

Nasal patency is key in PAP/NIV success.2 Patients with unrecognized nasal obstruction are more likely to discontinue CPAP early after initiation. Nasal congestion, such as that caused by allergies, should be treated. Structural issues may contribute to difficulty breathing through the nose, such as a collapsing nasal valve, which corresponds to the narrowest and most collapsible part of the nose. In some patients, PAP may enhance obstruction at the level of the nasal valves due to the Bernoulli phenomenon, whereby air accelerating through a narrow portion of nasal passage will exhibit a drop in pressure, making the nostrils more prone to collapse at that weak point. Treating any nasal obstruction is essential to enhance comfort and adherence. Nasal dilator strips can also be used with CPAP.

Ideally, masks should be fitted in the supine position, as gravity may affect facial tissues and mask fit. For patients who sleep in various positions, a mask with a solid harness that does not displace easily is preferable. Softer masks with fewer attachment points may feel more comfortable on first try but will displace and cause leak more easily during the night. Individuals with dexterity issues may prefer a mask that is easy to put on and take off, such as one with pull-on headgear, or magnetic attachments (if no contraindications, such as a pacemaker, are present). Education is a key element: Patients should be taught how to apply and adjust their mask, and they should be instructed to clean it daily to optimize adhesion and reduce leaks.

In summary

Nasal masks should be considered first-line for most patients. Oronasal masks, including under-the-nose designs, should be considered the exception rather than the rule for CPAP and most NIV users. The best mask is the one that the patient is comfortable using, including in terms of ease of handling and maintenance. An individualized approach is required to optimize PAP adherence and effectiveness.

Marta Kaminska, MD, MSc, is a pulmonologist and associate professor at McGill University Health Centre in Montreal, Quebec, Canada, where she is medical director of the National Program for Home Ventilatory Assistance and director of the respiratory division.

David Zielinski, MD, is a pediatric pulmonologist and associate professor at McGill University Health Centre in Montreal, Quebec, Canada, where he serves as pediatric medical director of the National Program for Home Ventilatory Assistance and director of the pediatric sleep laboratory.

Veronique Adam, RRT, is a respiratory therapist with more than 20 years of experience in long-term ventilatory support, providing home care services to adult and pediatric populations in Montreal, Quebec, Canada.

This article appeared in volume 11, issue 3 of Montage magazine.

References

  1. Genta PR, Kaminska M, Edwards BA, et al. The Importance of Mask Selection on Continuous Positive Airway Pressure Outcomes for Obstructive Sleep Apnea. An Official American Thoracic Society Workshop Report. Ann Am Thorac Soc. 2020;17(10):1177-1185. doi:10.1513/AnnalsATS.202007-864ST
  2. Vahabzadeh-Hagh AM, Strollo PJ Jr, Takashima M, et al. The role of nasal patency in obstructive sleep apnea: an expert consensus. Front Sleep. 2026;5:1819496. Published 2026 Apr 28;5:1819496. doi:10.3389/frsle.2026.1819496