Written and maintained by CASRAI Editorial Board
Last updated
“CPAP mask” and “oxygen mask” name two genuinely different pieces of equipment, used for two different clinical purposes — this guide covers both, as separate use cases, rather than treating them as one product family. A CPAP mask is a patient interface for chronic, self-administered positive-airway-pressure therapy, worn nightly at home to treat obstructive sleep apnea. A simple or non-rebreather oxygen mask is an acute-care device for delivering supplemental oxygen to a patient with low blood oxygen, used in hospitals, EMS, and urgent-care settings for hours or days, not months or years. They are not interchangeable, they are not selected the same way, and a facility or home-care buyer who conflates them will order the wrong item. The two sections below are written independently of each other for that reason.
Where to source this: LAC, CASRAI’s sister medical-supply business, stocks both CPAP interfaces and acute oxygen masks in its CPAP & Oxygen Masks category for facilities and home-care buyers sourcing either device family.
CPAP Mask Interfaces: Nasal, Full-Face, and Nasal Pillow
A CPAP (continuous positive airway pressure) machine only works if the mask holds a stable seal against the face all night, at whatever pressure the patient’s titration study set. The three interface families trade off seal area, comfort, and tolerance of mouth breathing differently, and the “best” one is genuinely patient-specific — sleep clinics routinely have patients try more than one before settling on a long-term interface.
Nasal Mask
Covers the nose only, sealing around the nasal bridge and upper lip. It’s the most commonly prescribed default interface: a moderate contact area gives it a more reliable seal at higher pressures than a nasal pillow, without the bulk and larger leak surface of a full-face mask. It requires the patient to keep their mouth closed during sleep — if air escapes out an open mouth, the machine loses pressure at the nose to compensate, which shows up as noise, dry mouth on waking, and reduced therapy effectiveness.
Full-Face (Oronasal) Mask
Covers both the nose and mouth. It’s the standard fallback for patients who are chronic mouth-breathers during sleep, or who have nasal congestion, a deviated septum, or seasonal allergies severe enough to make nasal-only breathing unreliable overnight. The larger sealing surface is also its main drawback: more surface area means more places for a leak to start, and its bulk makes it the interface most associated with claustrophobic reactions, particularly at first use.
Nasal Pillow Mask
The smallest-contact interface: two soft silicone inserts seal directly at the nostril openings rather than resting over the nose. Minimal facial contact makes it the interface most tolerated by patients who feel claustrophobic in a nasal or full-face mask, and it’s a common choice for side sleepers, for patients who wear glasses or read in bed, and for anyone bothered by the sensation of a mask resting on the bridge of the nose. The tradeoff runs the other way from full-face: pillows have less margin at higher prescribed pressures, and direct nostril contact can cause irritation with sustained nightly use, especially at higher flow.
Selection Factors
- Leak tolerance at the prescribed pressure. Higher titrated pressures make any leak louder and more therapy-disrupting. A nasal mask generally tolerates a wider pressure range with a stable seal than a nasal pillow does; a full-face mask has the most leak paths to manage because it has the most sealing edge.
- Claustrophobia. As a general pattern, nasal pillows are best tolerated, nasal masks next, and full-face masks least — but this is a real, common reason patients abandon full-face masks specifically, which matters because full-face is also the interface most often clinically indicated for mouth-breathers. That tension is genuine, not a minor inconvenience, and is exactly why a trial period matters.
- Mouth-breathing. This is the single factor that most directly decides between “nasal-only” (nasal mask or nasal pillow) and full-face. A patient who reliably breathes through their mouth during sleep will lose effective pressure through a nasal-only interface regardless of how well it seals at the nose.
- Nasal congestion / obstruction. Chronic allergies, a deviated septum, or frequent congestion push toward full-face, independent of mouth-breathing habit, since nasal-only interfaces depend on a clear nasal airway to function at all.
One area of genuine practice variation, worth naming honestly rather than resolving one way: for a patient who mouth-breathes but otherwise tolerates a nasal or pillow interface well, some clinicians try a chin strap (to keep the mouth closed) before escalating to a full-face mask, while others move directly to full-face rather than adding a second point-of-failure device. Both approaches appear in sleep-medicine practice; neither is a settled, one-size-fits-all answer, and the right choice depends on how severe the mouth leak is and how the individual patient tolerates the chin strap itself.
Acute Oxygen Delivery: Simple Face Mask vs. Non-Rebreather Mask
This is a different device family solving a different problem: supplying supplemental oxygen to a patient whose blood oxygen level is low, typically for a period measured in hours to days rather than years. Neither mask below moves air under pressure the way a CPAP machine does — both simply deliver oxygen-enriched gas near the airway, with the patient doing their own breathing.
Simple Face Mask
A basic mask covering the nose and mouth, open at the sides with no reservoir bag and no one-way valves. Because it’s unsealed, it has to be run at a minimum flow — commonly cited as roughly 5 to 10 L/min — high enough to continuously flush exhaled carbon dioxide out through the side ports rather than letting the patient rebreathe it. It’s an appropriate step up from a nasal cannula for a patient who needs more supplemental oxygen than a cannula delivers, but doesn’t need the higher, more reliable concentration a non-rebreather provides.
Non-Rebreather Mask
A face mask with an attached reservoir bag and one-way flap valves: a valve between the mask and the bag keeps exhaled air from flowing back into the reservoir, and valves over the mask’s side ports limit room air from being drawn in on inspiration. It’s run at a high enough flow — often described as flush rate, commonly cited around 10 to 15 L/min — to keep the reservoir bag from visibly collapsing when the patient inhales. That combination makes it the highest-concentration oxygen delivery device available as a standard non-invasive mask, used for more acute hypoxemia, trauma, and situations like pre-oxygenation ahead of a procedure.
Neither device delivers a single fixed, precise FiO2 the way a Venturi mask does — actual delivered oxygen concentration on both varies with how well the mask seals against an individual patient’s face and with that patient’s own breathing pattern and minute ventilation. Clinical references commonly describe a simple mask as delivering a moderate range of supplemental oxygen and a well-sealed non-rebreather as capable of delivering a substantially higher concentration than that, but treat both as estimates rather than guaranteed numbers when the actual figure matters clinically — that’s what a Venturi mask or titrated device exists to provide instead. A related, less commonly stocked device, the partial-rebreather mask, sits between the two: it has a reservoir bag like a non-rebreather but no one-way valves, so some rebreathing of the patient’s own exhaled air does occur.
Stocking Both Categories
Because these are functionally unrelated devices, a facility formulary or home-care supplier typically stocks them from entirely separate product lines rather than substituting one for the other: CPAP interfaces from a sleep-therapy supply line sized and fitted to an individual patient, and acute oxygen masks as a standard emergency/respiratory stock item sized more generically (adult/pediatric) and kept on hand in volume for immediate use.
Frequently Asked Questions
Is a CPAP mask the same thing as an oxygen mask?
No. A CPAP mask is part of a positive-pressure system that holds a patient’s airway open during sleep to treat obstructive sleep apnea; it doesn’t, by itself, deliver extra oxygen. A simple or non-rebreather oxygen mask delivers supplemental oxygen-enriched gas without applying pressure. Some CPAP setups can have supplemental oxygen bled into the circuit when a patient needs both therapies, but that’s a specific clinical addition, not the CPAP mask’s basic function.
Which CPAP mask is best for someone who feels claustrophobic?
A nasal pillow mask is generally the best-tolerated option for claustrophobia because it has the smallest facial contact area. The tradeoff is reduced margin for leaks at higher prescribed pressures and more nostril irritation with sustained nightly use, so it isn’t automatically right for every patient at every pressure setting.
Do mouth-breathers need a full-face CPAP mask?
Often, but not always as a first step. Full-face is the most direct fix for chronic mouth leak, but some clinicians try a chin strap with a nasal or nasal-pillow mask first. Practice varies here; there isn’t one settled answer.
What’s the practical difference between a simple oxygen mask and a non-rebreather mask?
A simple mask is unsealed, has no reservoir, and needs continuous flow just to flush exhaled air out its side ports. A non-rebreather adds a reservoir bag and one-way valves that limit room-air entrainment and rebreathing, which is what lets it deliver a notably higher oxygen concentration — it’s the device used for more acute or severe hypoxemia.
Can a non-rebreather mask be used with a CPAP machine?
No, they’re different systems built for different jobs. A non-rebreather is a passive oxygen-delivery mask meant for a standard oxygen flow source, not a positive-pressure circuit; it isn’t designed to be sealed onto or driven by a CPAP unit.
