Explanation of expiratory mouth breathing with normal inspiratory flow morphology

[AHMF]

Hi all,

I've been trying different things to try and optimise my CPAP therapy. Different masks, pressures, EPR settings etc. I have chronic nasal congestions, and I'm not too keen on mouth taping. Between pillows, FFM, and a hybrid-FFM I've found the hybrid to be the most successful. I struggle with aerophagia as well, again the hybrid seems to make that less of an issues for me.

However, during a nap during the day today I've seen a long period of what I believe to be expiratory mouth breathing with normal inspiratory flow morphology (see attached pics). I'd dialled down the EPR to 2, but the pressure at 13 is around where I seem to be optimal and I've been around that pressure for about a week but with the EPR at 3 normally.

Can any one explain to be exactly what expiratory mouth breathing with normal inspiratory flow morphology is, and why I might be seeing it?

Thank you.

[ChicagoGranny]

I have chronic nasal congestions

Have you been examined by an ENT and given a treatment plan?

People tend to tolerate this problem for years, even though there are a variety of good treatments.

[AHMF]

I have chronic nasal congestions

Have you been examined by an ENT and given a treatment plan?

People tend to tolerate this problem for years, even though there are a variety of good treatments.

Unfortunately not, it's extremely difficult to get to see any type of specialist in the UK at the moment. The waiting list is years. Our health systems is broken.

[robysue1]

Can any one explain to be exactly what expiratory mouth breathing with normal inspiratory flow morphology is, and why I might be seeing it?

Expiratory mouth breathing with normal inspiratory flow means you are inhaling through your nose and exhaling through your mouth.

Why would it be happening? Well it could just be the way your facial muscles relax when you are asleep. Or it could be that you usually exhale through your nose, but if air gets into your oral cavity you have a tendency to open your mouth to exhale it.

It really isn't much of a problem when you are using a hybrid full face mask because mouth exhalations do not trigger large leaks because the mask covers the mouth as well as the nose.

My own advice? Don't overthink this "problem". Seriously, since there are no leaks that could be affecting the efficacy of your therapy, you don't need to worry about it. Focus more on subjective quality of your sleep: Do you wake up feeling rested? Do you have enough energy to get through your day without feeling like you're excessively dragging. (Naps may or may not be a problem; it depends on whether you find the naps refresh you and whether or not they interfere with getting to sleep at a reasonable hour when night comes.)

You also write:

I have chronic nasal congestions

Are you using a heated humidifier with your CPAP? If so, what is it set to? And is your night time congestion better, worse, or about the same as your daytime congestion?

Things you can try for the chronic nasal congestion include:

• Saline nasal sprays as needed. (Not decongestant sprays like Afrin)
• A neti pot or a saline nasal rinse once or twice a day.
• If the congestion is related to allergies, making sure you do what you can to eliminate or minimize exposure. If the allergy is to dust mites, that can be difficult, but not impossible.
• If the congestion if related to allergies, then OTC anti-histamines can help. If you can obtain a nasal steroid spray (i.e. Flonase here in the US) OTC, then that can also help if you are patient. Nasal steroid sprays help ease inflammation in the nasal passages, but they don't directly treat the congestion itself.
• Changing the humidifier setting on the CPAP. You should be open to trying both less humidity as well as more humidity. Some noses really don't like a lot of added moisture and they can get more congested the higher you set the humidifier. Other noses are easily dried out by the positive air pressure and get clogged up as a result; they need the humidifier to be set to a higher setting.

[AHMF]

Can any one explain to be exactly what expiratory mouth breathing with normal inspiratory flow morphology is, and why I might be seeing it?

My own advice? Don't overthink this "problem". Seriously, since there are no leaks that could be affecting the efficacy of your therapy, you don't need to worry about it. Focus more on subjective quality of your sleep: Do you wake up feeling rested? Do you have enough energy to get through your day without feeling like you're excessively dragging. (Naps may or may not be a problem; it depends on whether you find the naps refresh you and whether or not they interfere with getting to sleep at a reasonable hour when night comes.)

Understood, it was just a pattern that jumped out to me really due to the length of time it continued for, because I hadn't seen it to that extent previously, and because I'd adjusted the EPR down to two. I'm assuming that the EPR set at three is infact providing me with a decent amount of expiratory relief given this new data. Would you agree?

You also write:

I have chronic nasal congestions

Are you using a heated humidifier with your CPAP? If so, what is it set to? And is your night time congestion better, worse, or about the same as your daytime congestion?

Things you can try for the chronic nasal congestion include:

• Saline nasal sprays as needed. (Not decongestant sprays like Afrin)
• A neti pot or a saline nasal rinse once or twice a day.
• If the congestion is related to allergies, making sure you do what you can to eliminate or minimize exposure. If the allergy is to dust mites, that can be difficult, but not impossible.
• If the congestion if related to allergies, then OTC anti-histamines can help. If you can obtain a nasal steroid spray (i.e. Flonase here in the US) OTC, then that can also help if you are patient. Nasal steroid sprays help ease inflammation in the nasal passages, but they don't directly treat the congestion itself.
• Changing the humidifier setting on the CPAP. You should be open to trying both less humidity as well as more humidity. Some noses really don't like a lot of added moisture and they can get more congested the higher you set the humidifier. Other noses are easily dried out by the positive air pressure and get clogged up as a result; they need the humidifier to be set to a higher setting.

[/quote]

I use a natural based nasal spray three times a day, and always before sleeping. I also use nasal strips, and a saline nasal douche (I think that's what it's called) before bed each night. I do have an allergy to dust mites and do all I can to minimize that issue, so air purifiers, wooden floors (laminate unfortunately) with regular hoovering with a hypoallergenic filter etc. Unfortunately for the last 15 months I've been dealing with post viral syndrome, which has been extremely debilitating in all sorts of ways, including mast cell issue, so I'm on combination of antihistamines and mast cell stabilisers which do seem to be helping.

I have the humidifier set at six, which seems to be about optimal for me. So I think I'm good there.

I'm thinking of adding in a VCOM, so that will be interesting. Hopefully that may improve comfort levels while also improving therapy and aerophagia, which is a major issues for me.

[Miss Emerita]

Robysue1, I was interested to see your reply, because I really puzzled over an answer to the OP's question. But I'm still puzzled. I get why we see that flow-rate trace when people using pillow or nasal masks breathe out through their mouths; the air has gone somewhere, and it has exited into the bedroom, or wherever. But with a FFM, doesn't the air stay in the closed system whether it's exhaled from the mouth or the nose? (Closed except for venting, of course.)

[AHMF]

Robysue1, I was interested to see your reply, because I really puzzled over an answer to the OP's question. But I'm still puzzled. I get why we see that flow-rate trace when people using pillow or nasal masks breathe out through their mouths; the air has gone somewhere, and it has exited into the bedroom, or wherever. But with a FFM, doesn't the air stay in the closed system whether it's exhaled from the mouth or the nose? (Closed except for venting, of course.)

Yes I had wondered the same, is it possible for the machine to identifying this type of breathing pattern within an effectively closed circuit. The mask fit is good as is the leak rate graph at the time of this event, and as you can see from the images I posted, there are no real leaks to speak of, while the insp.time and exp.time graphs look pretty wild. It has me a bit baffled, not to mention concerned.

[AHMF]

Robysue1, I was interested to see your reply, because I really puzzled over an answer to the OP's question. But I'm still puzzled. I get why we see that flow-rate trace when people using pillow or nasal masks breathe out through their mouths; the air has gone somewhere, and it has exited into the bedroom, or wherever. But with a FFM, doesn't the air stay in the closed system whether it's exhaled from the mouth or the nose? (Closed except for venting, of course.)

Here is an answer from Perplexity, which is an AI that uses high level verified sources for it's answers. I've included the sources it used for it's answer if it's of interest.

Note, I had turned down the EPR from 3 down to 2. I'd also note I was wearing a cervical collar to try and stop my mouth from falling right open and causing mask leaks.

AI Answer:

In a closed CPAP system with a well-fitting full face mask and no leaks, it is indeed possible for a patient to experience mouth breathing while maintaining normal inspiratory flow morphology. This can occur due to several factors:

1. **Mouth Breathing as a Habit**: Some patients may habitually breathe through their mouth even when using a full face mask. This could be due to nasal obstruction or simply a preference or habit, which can persist despite the mask's design to accommodate both nasal and oral breathing[2][5].

2. **Pressure Settings and Comfort**: Changes in CPAP settings, such as the Expiratory Pressure Relief (EPR), can affect how comfortable a patient feels during exhalation. If the pressure is not optimal, patients might unconsciously resort to mouth breathing during exhalation to alleviate discomfort[2].

3. **CPAP Machine Detection**: CPAP machines can often detect mouth breathing through changes in the flow rate and pressure patterns. While a full face mask reduces the likelihood of significant therapy disruption from mouth breathing, the machine's sensors can still identify variations in breathing patterns, such as those caused by mouth breathing, by analyzing the flow rate graph and other parameters[5][6]. While mouth breathing in a full face mask is less likely to cause significant leaks or therapy inefficacy compared to a nasal mask, it can still impact the overall comfort and effectiveness of the therapy. Adjustments to the mask fit, pressure settings, or additional interventions like chin straps might be necessary to address persistent mouth breathing[5][7].

Sources [1] The Impact of Mouth-Taping in Mouth-Breathers with Mild ... - NCBI https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9498537/ [2] Treatment Failure of Continuous Positive Airway Pressure with a Full ... https://www.e-jsm.org/journal/view.php?number=215 [3] Relationship between Oral Flow Patterns, Nasal Obstruction, and ... https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4513262/ [4] Mouth puffing phenomena of patients with obstructive sleep apnea ... https://link.springer.com/article/10.10 ... 22-02588-0 [5] CPAP Masks and Problems with Mouth Breathing https://www.sleepresolutions.com/blog/c ... -breathing [6] CPAP Machine: What It Is, How It Works & Side Effects https://my.clevelandclinic.org/health/t ... ap-machine [7] Best CPAP Masks for Mouth Breathers - Sleep Foundation https://www.sleepfoundation.org/best-cp ... -breathers [8] Waves of Precision: A Practical Guide for Reviewing New Tools to Evaluate Mechanical In-Exsufflation Efficacy in Neuromuscular Disorders https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11084470/

[robysue1]

Robysue1, I was interested to see your reply, because I really puzzled over an answer to the OP's question. But I'm still puzzled. I get why we see that flow-rate trace when people using pillow or nasal masks breathe out through their mouths; the air has gone somewhere, and it has exited into the bedroom, or wherever. But with a FFM, doesn't the air stay in the closed system whether it's exhaled from the mouth or the nose? (Closed except for venting, of course.)

The air you exhale into a mask is intentionally vented through the mask's vents. This is true regardless of whether you are exhaling through your nose into any kind of a mask or exhaling through your mouth in a FFM. The machine's algorithms are designed to use the subtle changes in the amount of airflow into the mask that is needed in order to maintain the desired pressure to calculate the air flow into/out of the lungs. (For bi-level machines or when you are using something like EPR, the change in airflow needed to allow the pressure to be reduced by the appropriate amount also has to be figured into the calculation of the air flow into/out of the lungs.)

In other words, the flow rate curve drawn by Oscar or SleepHQ is derived from the only raw data the machine can measure, which is the rate air is being pumped into the semi-closed system and the pressure that machine is maintaining through that air being pumped into the semi-closed system. (If you are sensitive to such things, you can sometimes get a feel the change in the amount of air being blown into the system by detecting subtle differences in how much air is being vented through the mask's vents.)

It's also worth mentioning that the machine's programming and algorithms are robust enough to accurately compute the air flow into/out of the lungs even in the presence of moderate sized leaks, at least most of the time. In other words, the machine's programming is robust enough to figure out how much of the change in air flow into the system is being caused by the need to add more air to overcome a moderate sized unintentional leak in order to maintain the desired pressure and how much of the change is air flow can be attributed to the air flow into/out of the lungs. (You can sometimes tell that a reasonably large and long leak is starting to affect the machine's capacity to track the breathing when the apparent size of both the inhalations and the exhalations is quite small, but (often) the shapes of those inhalations and exhalations remains somewhat normal looking.)

The shape of the exhalation part of the flow rate shows hows the exhalation was physically done. When breathing only through the nose, a typical exhalation builds at a moderate rate until it reaches its peak and then tapers off, often with a short pause where no air is going in or out of the lungs at the end of the exhalation.

When you typically inhale through your nose and exhale through your mouth, the way the exhalation is physically done is different: the rate of exhalation starts quite strong and sudden---i.e. the sudden downward peak at the beginning of the exhale---and then levels out at a relatively constant, but low rate for the rest of the exhalation. The exhalation rather suddenly ends when the mouth closes and you start to inhale through the nose. And it's this difference in how the rate of exhalation physically happens that gives the exhalation part mouth breathing its characteristic shape.

Finally, I'll add this: It's hard to grasp intuitively, but the area trapped between the exhalation curve and the 0-line for one mouth exhalation is just about equal to the area trapped between the inhalation curve and the 0-line for one nasal inhalation in this "inhale nasally, exhale orally" pattern. That's because the area trapped by the very short, but steep downward exhalation burst at the start of the exhalation combined with the fact that the exhalation never tapers off to a rate of essentially 0 L/min near the end of the exhalation.