Mask carbon dioxide levels - toxicity

Todzo wrote:It is interesting to see how if issues which deal with air hunger and carbon dioxide maintenance come up here the shills, trolls, and their sock puppets also appear. Sometimes you can tell them because they tend to use very gross avatars.

miltf wrote: The S9 is set at 5 cm constant pressure.

miltf wrote:Hi,
This is my first post here. I am a relatively new CPAP user (6 months). Initially, I found that the silicone in most masks gave me nasal congestion, so I switched to Sleepweaver masks which are cloth. No congestion, but I sometimes had a shortness of breath feeling. I thought maybe the fixed vent rate on the mask was too low as it felt like my expired breath was not leaving the mask before I took a new breath. Well, long story short, the company and I had an email exchange which remains unresolved for me and I went ahead and measured the CO2 in the mask using a very sensitive and rapid sensor called a SprintIR (details upon request).

The measured CO2 in the mask air space ranges from 2-3.3% during use (air is less than 0.1%, exhaled breath is 3-5%). The US OSHA sets a limit on CO2 of 1% (time weighted average) and says that higher levels can lead to discomfort (!), headache, lethargy, etc. Levels above 3% are not allowed for any length of time. I made some holes in the mask wall to increase the vent rate and decrease the CO2 and, sure enough, my nights are far more comfortable. My ResMed S9 Autoset seems to adjust very well to this change and for the most part, this problem is solved for me.

However, I am still concerned about other users of CPAP. I have measured the two other masks I happened to have, a Respironics Profile Lite (2-3%) and a ResMed Swift FX (1.5-2.5%) and both of these have high CO2 levels. My guess is that most masks are not designed to achieve adequate venting of CO2, partly because of inadequate vent rate but mostly because of vent placement. I think this must contribute to the low compliance rate for CPAP among those who are prescribed this technology. After all, if you are feeling discomfort, headache and lethargy, you might as well just stick with OSA.

I'm putting this information out on this forum because I don't know what else to do with it. I'll be interested to hear your thoughts.

Milt

Todzo wrote:It is interesting to see how if issues which deal with air hunger and carbon dioxide maintenance come up here the shills, trolls, and their sock puppets also appear. Sometimes you can tell them because they tend to use very gross avatars.

49er wrote:

Todzo wrote:It is interesting to see how if issues which deal with air hunger and carbon dioxide maintenance come up here the shills, trolls, and their sock puppets also appear. Sometimes you can tell them because they tend to use very gross avatars.

So anyone who disagrees with you is a shill, troll, or sock puppet? Hmm.

And claiming that folks who use gross avatars fit the above description makes about as much sense as my claiming that I can paint as well as Monet.

49er

Wulfman... wrote:Another discussion I was also part of about 7 years ago had to do with certain masks also not sufficiently clearing CO2.

Todzo wrote:Sometimes you can tell them because they tend to use very gross avatars.

Todzo wrote:Sometimes you can tell them because they tend to use very gross avatars.

Todzo wrote:The actual volumes inside the mask are low so you will be rebreathing very little additional air (keep in mind that we do not totally purge our systems and do rebreath some air as part of normal healthy breathing). And indeed a more common problem with CPAP use is carbon dioxide maintenance so some have come up with ways to help this which include enhancing the rebreathing space[1] or adding carbon dioxide at critical phases in the breathing process[2].

If the mask vent is working properly I would not worrry about it.

[1]: Gilmartin G, McGeehan B, Vigneault K, Daly RW, Manento M, Weiss JW, Thomas RJ.
Treatment of positive airway pressure treatment-associated respiratory instability with enhanced expiratory rebreathing space (EERS).
Source: J Clin Sleep Med. 2010 Dec 15;6(6):529-38. Division of Pulmonary, Critical Care and Sleep Medicine, Beth Israel Deaconess Medical Center, Boston, MA, USA.
Link: http://www.ncbi.nlm.nih.gov/pubmed/21206741

[2]: Dynamic CO2 therapy in periodic breathing: a modeling study to determine optimal timing and dosage regimes
Yoseph Mebrate, Keith Willson, Charlotte H. Manisty, Resham Baruah, Jamil Mayet, Alun D. Hughes, Kim H. Parker and Darrel P. Francis
J Appl Physiol 107:696-706, 2009. First published 23 July 2009; doi: 10.1152/japplphysiol.90308.2008
Link: http://www.ncbi.nlm.nih.gov/pubmed/19628721