Mask Leaks

Introduction to Leak

Air enters the CPAP machine from your room. It is drawn in through a filter, and is blown out in a controlled manner. Air blown out of the CPAP machine eventually leaves the machine - tubing - interface - person system and returns to your room. There are four possible routes by which air is returned to the room:

(1) A defect in the equipment, or equipment defectively assembled. This is always bad, and should be guarded against by frequent inspection, and periodic listening and feeling for extraneous airflow.

(2) Intentional venting. Virtually all commercial CPAP interface systems are designed so that air ALWAYS blows through them. This enables the moisture-laden, oxygen depleted, and carbon dioxide-rich air which you exhale into the interface to be continually "washed out" so that it is not re-inhaled. This venting is part of the interface design, with greater volumes of air being vented at higher pressures. Most manufacturers provide information as to how much leak will occur at various pressure levels. While often referred to as "leak," this normal, intentional venting should not be confused with "unintentional" leak.

(3) Skin leak. Virtually every interface device involves some sort of contact between a plastic "cushion" or "pillow" and the user's skin. Air can easily leak out through these contact points, particularly as the user moves around during the course of the night. This is the first type of "unintentional leak" which should ideally be minimized.

(4) Mouth leak - the second type of "unintentiional lead" which should ideally be minimized. Since the mouth and the nose are connected in the pharynx, unless a "Full Face Mask" (or other special interfaces which cover both the mouth and the nose)is used, air which enters the nose may leak out of the mouth. This can occur in several different ways (or in combinations) which may more-or-less affect the effectiveness of CPAP, and which may require different strategies for dealing with the leak:

(a) with "mouth breathing," in which unpressurized room air is inhaled - and exhaled - through the mouth,

(b) with "open mouth flow," in which air pressurized air entering through the nose more-or-less continually escapes through an open mouth, or

(c) with "mouth exhalation," in which pressurized CPAP air which is inhaled through the nose is partially or totally exhaled through the mouth.

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Mouth breathing and mouth leaks are closely related, but not necessarily the same thing.

Mouth breathing must occur when the nasal passages are blocked, so the only way for any air to get into the lungs is through the mouth. People with blocked noses breathe through their mouth, not through their nose. The solution to mouth breathing is to use a full face mask. Some effort and time may be required to find the best full face mask, fit it, and adjust to it. Use of nasal irrigation and humidified CPAP, especially with nasal pillows, may open nasal passages that were previously chronically blocked. The person can then learn to breathe through the nose.

Mouth leaks may occur if the person is breathing through their nose, but opens their mouth during sleep. If leakage through the mouth is a persistent problem, CPAP treatment can be rendered completely ineffective. CPAP air detouring out the mouth does nothing to keep the airway open. Either mouth breathing or mouth leakage can also cause feelings of suffocation from apneas still happening and/or just the choking feeling of air rushing out the mouth unexpectedly. The safest solution to mouth leakage is to use a full face mask.

http://www.cpaptalk.com/viewtopic/t23863/Why-dont-more-people-use-a-full-face-mask.html

Other remedies including using a homemade or commercial chinstrap in hopes that the tongue will maintain an airtight seal inside the mouth if the jaw is kept up. Many people find that chinstraps don’t work to prevent mouth leakage.

Another remedy is to use the tongue to maintain an airtight seal inside the mouth. Some people train the tongue by positioning the tip of the tongue behind the upper front teeth or on the roof of the mouth, and let the tongue spread out in back to seal the throat air passage, even if the lips open. Others use a dental splint, custom made by a dentist, or a do-it-yourself mouth guard to help the tongue maintain an airtight seal.

“The safety of taping the mouth shut has not been proven and there are potential risks of regurgitation and aspiration of food and of suffocation.” TS Johnson MD et al, Sleep Apnea – The Phantom of the Night, p. 167. Mouth taping is especially dangerous for anyone who ever gets blocked nasal passages during the night. If air can’t get in through the nose, it needs to get in through the mouth. Mouth taping is also risky in case of a hose disconnect or power outage.

Warning against mouth leakage

Whether you use a nasal mask or nasal pillows (or any other kind of mask except a full face), if air leaks out through your mouth, the PAP therapy will not work. There are two safe options. The first is to learn to keep your mouth closed while sleeping. Since the feel of pressurized air exiting your mouth is an unpleasant sensation, PAP aids in this. Some people position the tongue behind the top teeth and let it spread out in back to cover the throat opening and make a seal so the PAP works. The second option is to use a full face mask. If you are a mouth breather, breathing in through your mouth instead of your nose, a full face mask is required. An alternative practice for mouth leaks, mouth taping or sealing, is understandable but not advisable, and is not safe if your nose gets stuffy at night, you have acid reflux, need to regurgitate; or you have a hose disconnect or lose machine power and need to breathe through your mouth.

See also Mask Leaks Blow onto Partner