Want to get the old-time nosebreathing religion?

DreamStalker · Post by **DreamStalker** » Wed Jun 02, 2010 2:31 pm

jnk wrote:
roster wrote:
jnk wrote:
The process of pressurizing the airway generally requires venting the pressurized air at a rate that depletes the natural moisture of the throat and nose.
This one I will have to think about, but my initial gut feelings question its truth.

I have long maintained that an apneic person using a properly operating CPAP system will have no more airflow through any parts of his airway than if he were not apneic and breathed normally.

CPAP is only creating a pressure. The rise and fall of the diaphragm determines the volume and speed of the airflow.

Now the volume of airflow using CPAP, while not any greater, is more dense, but only by about 1% (at 10 cm CPAP).

So I have doubts that a properly working CPAP will cause any significant drying. Maybe someone with the appropriate engineering background will correct me.
I have no engineering background, in fact no "appropriate" background in anything much, but I believe it is the venting, not so much the pressure itself, that causes the drying. The air is vented to make sure CO2 is vented, but that process wicks away moisture at the same time, and a higher pressure makes for a higher vent rate and less moisture. That is why higher pressure may mean a higher setting on the humidifier, at least for some. Think about it, it is even venting while you are breathing in, not just breathing out. All that expelled air takes moisture away, because in that sense, there is increased airflow, not in and out of the throat, but out of the loop nonetheless. But I could be wrong. I often am.

(Please ignore all the weasel words used above--it is only my vain attempt to keep Rooster and his ilk from catching me on a technicality. )

But the amount of moisture being wicked out is no different than the amount wicked out under normal breathing. In other words, the moisture requires the airflow to transport it and if theres is no difference in airflow there is no difference for moisture either.

jnk · Post by **jnk** » Wed Jun 02, 2010 2:35 pm

I reedited my preceding comment to make my point on airflow more directly.

ResMed puts it this way (notice the mention of airflow) at the site I linked to before, http://www.resmed.com/us/patients_and_f ... c=patients:

This therapy creates a new climate for your nose and upper airway because airflow is greater than what your body is accustomed to humidifying – and the greater your treatment pressure the more difficult this task becomes. Your nose may become tender or dry, or it may respond to the new environment by creating more mucus to protect its sensitive tissues. A humidifier can prevent and even reverse these symptoms by treating the air before it even reaches your nose.

I doubt that was written by the docs or engineers, but those humidifier salesmen may still have a point, right?

jnk · Post by **jnk** » Wed Jun 02, 2010 2:59 pm

It may be that what I am describing is more a problem for me because of the proximity of the vent to my nostrils on my nasal pillows. If I don't use humidity, I wake up with very dry nostrils at the front of my nose. If I do use humidity, my nose doesn't bother me. And that seems to harmonize with the point by those same cleverly-disguised humidifier salesman at their "support" site here:

If the CPAP begins to dry your nose, your body will increase the production of mucus in the nose to add more moisture to the inhaled air.--http://www.sleepapnea.org/resources/pubs/wrong.html

roster · Post by **roster** » Wed Jun 02, 2010 3:06 pm

jnk wrote: but I believe it is the venting, not so much the pressure itself, that can cause the drying. The air is vented to make sure CO2 is vented, but that process wicks away moisture at the same time, and a higher pressure makes for a higher vent rate and less moisture.

Not accepted.

If you want to argue that some part of my facial skin, being under the mask and under the path of air flowing from the mask intake directly out to the exhaust vents is being dried out by CPAP, then I accept that. There is possibly more airflow with CPAP over parts of the skin. Well hell, you could argue it is drying out my wife's skin as it blows over her arm. But there is no additional airflow within my cavities.

I told my sleep doc that CPAP doesn't dry you out anymore than normal breathing. She did not believe me, just like you.

roster · Post by **roster** » Wed Jun 02, 2010 3:12 pm

jnk wrote:It may be that what I am describing is more a problem for me because of the proximity of the vent to my nostrils on my nasal pillows. If I don't use humidity, I wake up with very dry nostrils at the front of my nose. If I do use humidity, my nose doesn't bother me. And that seems to harmonize with the point by those same cleverly-disguised humidifier salesman at their "support" site here:

If the CPAP begins to dry your nose, your body will increase the production of mucus in the nose to add more moisture to the inhaled air.--http://www.sleepapnea.org/resources/pubs/wrong.html

Just use your humidifier and ignore me.

Down here it is 53% R/H and 78F in my bedroom. I won't need the CPAP humidifier until December or January and then only on the driest nights (35% R/H or lower).

jnk · Post by **jnk** » Wed Jun 02, 2010 3:18 pm

roster wrote: . . . I won't need the CPAP humidifier until December or January and then only on the driest nights (35% R/H or lower).

Suit yourself. Just remember:

"The relative humidity (rH) of the air delivered by the nCPAP device is, on average, 20% lower than the rH of room air."
--http://chestjournal.chestpubs.org/conte ... 0.full.pdf

roster · Post by **roster** » Wed Jun 02, 2010 3:33 pm

jnk wrote:
"The relative humidity (rH) of the air delivered by the nCPAP device is, on average, 20% lower than the rH of room air."
--http://chestjournal.chestpubs.org/conte ... 0.full.pdf

In the article they say,

Recently, the use of a full face mask has been shown to completely prevent dehydration of the respiratory tract

So I think the guys in the article are talking about drying yourself out by using a nasal mouth and mouthbreathing. cpaptalk members know better than to do that.

I have to go out to dinner. If you read the complete article, let me know what you think.

jnk · Post by **jnk** » Wed Jun 02, 2010 6:04 pm

roster wrote: . . . So I think the guys in the article are talking about drying yourself out by using a nasal mouth and mouthbreathing. cpaptalk members know better than to do that.

I have to go out to dinner. If you read the complete article, let me know what you think.

I do think that mouthbreathing IS being discussed, but I do not think that it is the only thing being discussed. Perhaps we both agree equally with the statement in this earlier study:

In summary, we have demonstrated that heated humidification can prevent or lessen dehydration of inspired air during nCPAP therapy in patients with OSAS complaining of nasal symptoms, particularly when they suffer from a condition likely to promote mouth leaks."--http://chestjournal.chestpubs.org/conte ... 2.full.pdf

In that study, it was shown exactly the difference in relative humidity compared to without nCPAP, both with and without mouth leaks:

Compared with the control period of spontaneous breathing without nCPAP (80 +/- 2%), rH was significantly decreased when the CPAP apparatus was turned on (63 +/- 9%, p < 0.01) and markedly decreased when the patients were instructed to simulate mouth leaks (39 +/- 9%, p < 0.01).

jnk · Post by **jnk** » Wed Jun 02, 2010 6:43 pm

Nasal discomfort is generally due to the drying effect of the high airflow delivered by the CPAP machine. . . . The RH of the air delivered by CPAP is 20% lower than the RH of the surrounding air. . . . The drying effect of the CPAP airflow is known to increase airway resistance. . . . Evidence clearly demonstrates that lack of humidification leads to nasal and oral discomfort and morphological changes in the airway that lead to poor patient compliance. When a heated humidifier is added, the RH within the airway is significantly increased and patient compliance with therapy increases. . . . When the addition of heated humidity alone does not eliminate problems associated with CPAP use, then a full-face mask is an excellent option. Heated humidification along with a full-face mask may completely eliminate water loss in the airway when CPAP is used.--http://www.sleepreviewmag.com/issues/ar ... -05_02.asp

DreamStalker · Post by **DreamStalker** » Wed Jun 02, 2010 7:22 pm

I'm afraid Rooster is correct here. He qualified his assumption with ... "CPAP working correctly".

If the CPAP circuit contains mouth leaking, then yes, moisture will be lost.

roster · Post by **roster** » Fri Jun 11, 2010 5:45 pm

If all of the findings of this study were true, I would consider them very important findings for the comfort of the therapy. But I take issue with this finding:

. . . . The RH of the air delivered by CPAP is 20% lower than the RH of the surrounding air. . . . http://www.sleepreviewmag.com/issues/ar ... -05_02.asp

This finding of the study is not correct in my opinion. Something was wrong with their measurements or assumptions. They claim to have measured inspired air without CPAP and then measured air in the mask with CPAP (without a humidifier)

. …Relative humidity (rH) and temperature (T) of inspired air were measured using a specific transducer (Testor 171; Testo; Lenzkirch, Germany) inserted into the mask.

According to their findings, the inspired air without CPAP (room air) was about 80% RH and when CPAP was added, the RH of the air in the mask fell to 60%. Their conclusion is that CPAP is “drying” the air significantly.

Intuitively this makes no sense. CPAP takes room air (80% RH) and compresses it slightly. Compressing air does not remove water vapor from the air.

From another point of view, if CPAP (without humidifier) removed water from the air, especially as much as claimed in the study, where does the water go? I would expect to find water in the mask, hose, machine or soaking the intake air filter. From experience we know this does not happen in any climate with CPAP without humidifier.

There is something else that seems strange and, if true, is an indication that they did not have good control of the experiments. They state that in the daytime tests the temperature was 25C (77F) and the RH was 80%. This is a dewpoint of 70. These conditions are on the lower end of “oppressive” and most of us would be very uncomfortable trying to sleep in such conditions even with a ceiling fan. Conducting the experiment under such conditions is poor work in my opinion. (I suspect the RH of the room was a reasonable 60% and not 80% as reported. Of course I have no way of knowing this.)

I reject the study and continue to believe that unhumidified CPAP air reaches the nostrils at the same RH level as the ambient room air.

Jeff, If you are still following this thread, I would appreciate your comments. Thermodynamic engineers are also welcome to comment.

Goofproof · Post by **Goofproof** » Sat Jun 12, 2010 12:41 pm

For the past year I have used my XPAP in a room set at 65 degrees, with a de-humidifier running in the basement set at 55%. I use a nasal mask, without any water in my HH, with the heat off, the only time I get dry it's from mild mouthleaking. For that I take a hospital cup with ice and water in it, by morning I've used most of it. I keep distilled water in the house, but haven't needed it in a long while, it's getting pretty old. Jim

Amigo · Post by **Amigo** » Sat Jun 12, 2010 2:37 pm

For what it's worth...

I'm a nasal pillow user running a pressure range of 12 - 14.

On the rare (fortunately) occasions that I have forgotten to fill my APAP humidifier, I have spent the following day sneezing like crazy and using enough tissue blowing my nose to fill several wastebaskets. I use both the foam and paper filters so it's not a dust/pollen issue.

Perhaps it's just my "unique" nasal anatomy, but I REALLY need the extra humidification.

Before I switched to the PR1, I had the heating level set to '4,' year around. The bedroom has hot water heat in winter, A/C in summer.

With the PR1, I've found that the automatic humidification sensor works very well, and the volume of distilled water used is about the same as before for 7.5 hours of use.

Since the relative humidity of the room one sleeps in can vary enormously, I believe that the need for "extra" humidification will always be an individual choice.

Want to get the old-time nosebreathing religion?

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