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[Equipment] Rebreathing causing Hypercapnia (CO2 – Carbon Dioxide Poisoning)
#61
RE: Rebreathing causing Hypercapnia (CO2 – Carbon Dioxide Poisoning)
I would recommend that you start your own thread in the Main forum for this subject.  

I can see how the fine mesh on the P10 may cause problems, especially during high humidity conditions.  After cleaning my P10 I've seen that water will prevent or diminish this mesh's ability to allow gases to escape.  I can imagine that any rainout or nasal discharge could diminish its efficiency.  I usually use compressed air after cleaning to establish a "proper" flow condition.

I look forward to your report.
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#62
RE: Rebreathing causing Hypercapnia (CO2 – Carbon Dioxide Poisoning)
(02-11-2019, 03:15 PM)mdmarmd Wrote: I have read through this thread with great interest. I especially appreciate the persistent input from Hulk and the very thoughtful and detailed additions from DaveResmed P10.

As a physician who suffers from sleep apnea, has diagnosed several hundred patients with it, and uses an Airsense 10 and Airfit P10, I am intently aware of this problem.  I first brought this up when I first joined the forum:

http://www.apneaboard.com/forums/Thread-...Airfit-P10

There were all these dismissive disputes about whether this could ever even happen in a hi tech, FDA approved device as well as the use of leak rates to try and prove its not happening.

At that time I felt that the definitive way to resolve this issue was to measure the real-time PCO2 in the P10 tubing.  I obtained a highly sensitive CO2 sensor in 2016 to permit this but the supporting software was defective and after a prolonged wait for this to be addressed I finally gave up and moved on to other things.  

But now that I have the means to measure the CO2 I have recorded a number of capnographs that show the precipitous rise in CO2 that can occur within the P10.  One graph shows a sustained elevation to over 45,000 PPM (4.5 %) for over 35 minutes before I woke feeling very uncomfortable. I endured the discomfort and breathed more forcefully, which finally opened the vent and brought the PCO2 back down.

I also have very high powered pictures that show the characteristics of the webbed vents and factors that probably contribute to the risk of vent occlusion and resultant hypercapnea.

I intend to post this data but I am not sure where to do this because there are a number of threads like the one I started, this one and the very extensive 24 page thread.

http://www.apneaboard.com/forums/Thread-...fit+P10%22

Any input regarding where to post this would be appreciated.

Doug

Doug, you can start a thread in the main forum or write it as a review in the review forum. If you are presenting an article that has data and image support, we can even include it in a wiki article. Your call. I'm interested to hear your findings.  I'm one of those that was skeptical of this problem when it was originally reported, but have come to realize there are circumstances, alterations and maintenance procedures that may occlude the vents.
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#63
RE: Rebreathing causing Hypercapnia (CO2 – Carbon Dioxide Poisoning)
(02-11-2019, 03:15 PM)mdmarmd Wrote: But now that I have the means to measure the CO2 I have recorded a number of capnographs that show the precipitous rise in CO2 that can occur within the P10.  One graph shows a sustained elevation to over 45,000 PPM (4.5 %) for over 35 minutes before I woke feeling very uncomfortable. I endured the discomfort and breathed more forcefully, which finally opened the vent and brought the PCO2 back down.

Doug

Hi Doug,

I experienced this exact problem with my P10 mask. I had dialed up the humidity a few nights before. On the bad night I wound up with water in the fine mesh vents, and also with condensation in the rest of the mask and in the long tube. I didn't have access to a CO2 meter, but this problem is easily seen in the SleepyHead charts.

The simplest way to see this in the chart labelled "Leak Rate". It's mis-labelled. It actually means "Total Leaks". In my Dreamstation the terminology means this is the total airflow in L/min. It is not "leakage". On a normal night given a pressure of about 8, my Total Leaks is pretty steady at about 28. On the night in question it dropped to a low of about 2. Also, my Flow Rate was quite elevated as my body struggled to breathe. I have no idea why I didn't wake up!?

On that night I had slept in my recliner for about 4+ hours before using CPAP. I only used the machine for a few hours in the morning. That's why the time duration is so short.

In my notes from that day I said: I noticed a slight headache upon awakening. That doesn't happen that often. Headache still present one hour later.

The utterly simple solution for me was to turn down the humidity back to 3 from the 5 I set it to a few days earlier. I have never had the problem again.

It's very very important to keep the vents open for the Airfit P10.

   
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#64
RE: Rebreathing causing Hypercapnia (CO2 – Carbon Dioxide Poisoning)
Thanks for the suggestions. I need a bit more time to make my data presentable and then will probably post on the main forum.

Doug
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#65
RE: Rebreathing causing Hypercapnia (CO2 – Carbon Dioxide Poisoning)
Report on Hypercapnia with ResMed AirFit P10 is posted at:

http://www.apneaboard.com/forums/Thread-...YPERCAPNIA
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