EVIDENCE OF AIRFIT P10 VENT OBSTRUCTION CAUSING HYPERCAPNIA (also N30?)

[Mr Nosey]

Awhile back, I posted about problems with my Resmed p10 mask, where I'd experienced a shortness of breath after using the mask for a few months.

viewtopic/t174159/Problems-with-airflow ... d-P10.html

I followed up by routinely cleaning the vent, but found with time (or excessive humidity, that the symptom (shortness of breath) would return.

I wanted to follow up now with observations using a new mask, the Resmed N30. I do clean the mask routinely. Regardless, after a few months, I find the mask not usable as again, I have a shortness of breath..which I strongly assumed was due to clogged filter/build up of CO2).

F0lks who use the Resmed masks with diffusion filters might want to read this thread:
http://www.apneaboard.com/forums/Thread ... YPERCAPNIA

I think Resmed has designed a filter with limited life span (the air diffusion filter) so that they have ore sales due to need to more frequently buy their masks. Personally, I think the situation horrible...because there is no warning about this issue when purchasing their product AND the net effect is that the clogged filter (even with cleaning) can adversely affect the health of OSA patient.

Hope everyone is doing well during this trying time (pandemic).

Richard

[Mr Nosey]

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

(Content of the link)

EVIDENCE OF AIRFIT P10 VENT OBSTRUCTION CAUSING HYPERCAPNIA



EVIDENCE OF AIRFIT P10 VENT OBSTRUCTION CAUSING HYPERCAPNIA

PART 1

THE GOOD

I am recapping an earlier post I made to provide context for this post.

To begin, I would like to say that I love the Airfit P10 for its innovative solution to the problems with the headgear and vents of traditional nasal pillows.

I am a physician and have used well over 20 different products from full face to nasal mask and pillows since being diagnosed with OSA. I finally settled on the Resmed AirSense 10 Autoset and P10 pillows.

I found that its light weight, split head strap resulted in much improved lateral stability over the usual pillow design, which tended to pull upward and back. This was necessary because of the need to provide upward tension against the nostrils. The price was less lateral stability and leaks. This was compensated for with beefier straps for pulling the head gear tighter, resulting in discomfort and the inevitable depression marks on your face. The P10 headgear pulls both upward and downward resulting in force vector more directly backward from the nose while still maintaining a good seal. This creates a four-point restraint that makes the pillow much less prone to being dislodged by any lateral pressure or pull on the tubing. This avoids the need for undue tension on the headgear straps, more comfort and no facial marks.

I also found the vents to be an elegant solution to the problem of noise and the cold stream of air that characterized traditionally vented pillows.

Since I treat patients with anxiety, mood, and bipolar disorder, I know that the quality of their sleep can have profound implications on their symptoms and success of treatment. Since being diagnosed myself, I began to screen very carefully for OSA and have had a large number of patients get diagnosed with OSA. For most of these patients, my number one recommendation for non-mouth breathers is the AirSense 10, teamed with the AirFit P10 (when tolerated).

But now, I have to give them a warning: If you wake feeling short of breath, put the back of your hand (better if licked as moisture increases sensitivity) close to the vents, if your hand doesn’t detect a cool breeze, then your vents could be obstructed. Look to see if there is rainout in the tube.

THE BAD

In 2016, I had discovered a problem after using a P10 for about 6 months. It was now in the winter and the ambient room temperature was cooler. I was using the Resmed insulated jacket for the heated supply hose, with the heater and humidity set in the middle ranges.

I awoke abruptly one night with acute dyspnea (sensation of shortness of breath) and tachypnea (rapid breathing). I immediately thought of hypercapnia and checked for flow from the vents: There was none. On examination, there was slight condensation in the tubing.

While holding the pillows forcefully against my face I exhaled as hard as I could into the pillows. I could feel a fine mist of water hit my hands and then I could feel that the air was exiting the vents again. The vents seemed to clear and I tried to resume sleeping, but I soon awoke with it plugged again.

There was another clue that the vents were obstructed. One night I awoke dyspneic and heard a strange crackling sound in front of me. I realized it was coming from the vents so I put my phone close to them and recorded the sound. This crackling noise was the result of my increased efforts to inhale, which overcame the surface tension of the water covering the “pores” in the vent. But the pores quickly resealed as the crackling persisted with each inhalation and no air was flowing out the vents. Of note, the crackles only occurred on inhalation, not exhalation, meaning there was no flow out the vents even with heightened respiratory effort. You can hear this recording at:

Opening Snaps

I wondered why, after prolonged use I had suddenly experienced complete occlusion of the vents. It had occurred without any warning. So, I searched the Apnea Board Forum to see if others were experiencing a similar problem and was directed to a relevant thread--now 24 pages long!

I read that others were experiencing abrupt blockage of the P10 vents despite an initial period without problems. Some attributed it to moisture trapped in the vent layers, leading some to advocate never cleaning or wetting the vents. Some were resorting to perforating the vents with pin holes or slits. Others kept one in reserve or just gave up on the mask altogether.

Others were dismissive, not believing this could possibly be a problem: Afterall, Resmed is a high-tech medical device company that spends lots on R&D and would never risk the liability of such a design defect. It was FDA approved after all.

Some used leak rates in an attempt to disprove possible vent obstruction. Still others claimed that one could never overcome the pressure of the CPAP fan by rebreathing upstream in the tube and that any increase in CO2 would quickly be flushed out. And some said a person would be forced to awaken by hypercapnia and that the mouth would be the obvious safety valve, preventing any substantial rise in CO2.

AND THE UGLY

But I was certain the obstruction was, in fact, occurring. I decided to find more definitive ways to answer this question. First, I acquired a digital microscope to better understand the nature of the vents. This allowed me to use 60-250x magnification.

This revealed that the vents consisted of tightly woven, layered fibers. I then compared the P10 that had obstructed to a brand new one. The older one appeared slightly grey/brown to the naked eye, but magnification revealed that the old P10 had accumulated very fine deposits of dust particles deep within the interstices of the web. These deposits were visible on both the outer and inner surface of the web. The pattern of the web surface was also different on each side. The inner side seemed to have a tighter pattern of deeper pockets where the dust deposited in bands

I attempted to clean out the deposits with soft brush and soapy wash as suggested in the manual. This did remove a fair bit of more superficial dirt but seemed to leave the deepest deposits. Presumably, these deposits likely accumulate in the areas of greatest airflow and are first to accumulate and hardest to dislodge.

I decided to try something more radical. I filled the P10 tube with soapy water, blocked the pillow outlets and submerged it under water. I then directed blasts of air into the tube from my 100 psi compressor. My thought was this burst of water propelled by a bubble of air would likely distend the web enough to allow for the deposits to wash free. Indeed, the vents were pretty clean after this process. But this was hardly a handy solution for most people.



EVIDENCE OF AIRFIT P10 VENT OBSTRUCTION CAUSING HYPERCAPNIA--PART 2


At this point I felt I had defined the problem: Use of the P10, even with proper CPAP filter maintenance will eventually lead to fine deposits of dust in the webbing, just as with any filter. While not initially a problem, once critical mass is reached along with rainout conditions, the dust turns to “mud” and effectively occludes the vents.

Still, I felt the definitive proof that the vents were truly obstructed and clinically significant would require proof of a measurable increase in CO2 in the tubing.

To this end, in late 2016, I decided to make a capnograph to measure the CO2 within the P10 tubing. I acquired a very sensitive carbon dioxide sensor that could measure 0-20% CO2 at 20 times per second. Unfortunately, the software to support this instrument proved faulty and after waiting 6 months for this to be resolved, I lost interest and moved on to other things.

But in 2018, I was spurred on to renew my efforts with the onset of winter, since I knew that this phenomenon most likely occurred in cooler weather when the P10 was more susceptible to rainout conditions. I also read of additional reports of blocked P10s in the sleep apnea forum in a recent thread started by Hulk, with very inciteful comments by DaveResmedP10 who persevered in pushing back on those who dismissed his concerns:

Rebreathing causing Hypercapnia (CO2 – Carbon Dioxide Poisoning)

I already had all the components for the capnograph:
1 thin anesthesia gas sampling line 6 Nafion dryer tube
2 water trap 7 Air pump
3 particulate filter 8 CO2 sensor and housing
4 hydrophobic filter

It is, however, a simplified instrument, and I don’t suggest it has the precision of a medically approved device. It does respond almost instantaneously to changes in CO2, and I do believe it is sufficiently sensitive for the intended purpose.

Because I wanted to induce the conditions that I suspected caused the obstructions, I used a P10 that was probably 7 months old. I kept the room cool, in the mid to upper sixties. I did not use an insulating jacket on my heated tube, and set the temperature to around 78 degrees and the humidity to 5-6 on the AirSense 10. The intake for the gas sampling was positioned at the junction between the P10 tubing and the supply hose. This level typically was proximal enough from the pillows that, under normal ventilation, the CO2 level was close to ambient room levels. I figured that a substantial rise at this juncture must mean the vents are restrictive enough to result in significant accumulation and rebreathing of CO2.

I believe this capnographic data shows, conclusively, that the P10 vents do, in fact obstruct under conditions where there is a significant degree of residual dust trapped in the vents, as well as moisture from condensation.

The resultant acute rise in CO2 forces the rebreathing of levels approaching end-tidal CO2. I can tell you that after a brief period of hypercapnia I would wake up feeling very short of breath and be breathing rapidly. Sometimes I would just rip the mask off in my sleep. At other times, I awakened and tried to continue breathing in the P10 to see if the obstruction could resolve spontaneously. On a few occasions the vents did reopen, and I then continued to sleep through several subsequent elevations.

In graph 7, I awakened quite dyspneic. But I was determined to keep breathing into the P10 to see what would occur (may not have been the safest thing to do). I had to fight the growing urge to breath more rapidly or to rip the mask off. I began to feel quite unwell. Hard to describe: A feeling of restless anxiety, headache, mild grogginess and slight nausea. Ultimately, I had to abort the test by forcefully blowing into the P10 several times until it reopened. But subsequently, I didn’t feel well for 30-45 minutes and was not able to fall back to sleep for quite some time.

I believe that this data proves the P10 vents can occlude resulting in rebreathing of very high levels of expired CO2. I also believe it dispels the notions that significant hypercapnia would always provoke awakening or that the natural safety valve, namely one’s mouth, would always come to one’s defense.

Finally, as I was reading through Hulk’s recurrent question about where the air was going if it wasn’t going out the vents, I decided it would be useful to actually measure the CO2 inside the intake port of the AirSense 10 to see if there was any evidence that rebreathed air was backing up all the way through the CPAP (see GRAPH .

What I found was that, with the vents completely occluded, I could quickly detect a rise CO2. It did not rise way up, going from around 700 PPM to 900-1500 PPM where it reached a steady state. It seemed there was a lot of churn at the port entrance, as I could feel an ebb and flow and the levels would fluctuate if I moved my fingers around the port. Switching the sampling line to the P10 revealed that the CO2 within the tube was over 35,000 PPM. The leak rate did not indicate that the vents were completely obstructed. The only leaking taking place was back out the intake unless there are other leak sites in the CPAP. When the vents are obstructed, it’s actually quite easy to exhale into the CPAP. It almost felt like the resistance I felt before using the EPR. With the vent’s blocked, there is not the same pressure differential from CPAP to the vents.

[Pugsy]

Well....as someone who used the P10 for many years with a very high humidity setting and rarely cleans anything and used the same frame/filter for years without replacing anything but the pillow or headgear...
I have never ever experienced what you experienced. So while you have a problem, not everyone else in the world has that problem.
Believe what you want to believe but it isn't common and ResMed didn't design the diffused venting to increase sales in this way.

You get to state your personal opinion here....as do I and my opinion differs widely from yours. I am not wanting to engage or discuss.
Just stating an alternate viewpoint for others to read and they get to form their own opinion.

[jimbud]

Man, you sure have a lot of spare time on your hands.

I used the P10 for over a year.
Cleaned it with Dawn and rinsed it (used a dental water pic about every three months.just for luck)
I would hold it up to a bright light with a new pillow cushion.
No difference.
It is a great pillow mask.
Just keep it clean.

Became a mouth breather so had to change to F30i.
Otherwise I would be a solid P10 lifetime user.

JPB

[Goofproof]

One added point, I don't use the mask, but If you used a good cpap data reader like "Oscar" ect, You can see the vent rate, by compairing that leak rate with the mask vent rates you can SEE if you are not venting enough. Then you correct the problem, If it's plugged up, I'd suspect your cleaning isn't up to snuff. Jim

[LSAT]

This is great for sleep apnea...I almost fell asleep reading all of that.

[jimbud]

This is great for sleep apnea...I almost fell asleep reading all of that.

You're a better man than I am Gunga Din.
I just caught the gist and posted.
Best I could do.

JPB

[Mr Nosey]

Well....as someone who used the P10 for many years with a very high humidity setting and rarely cleans anything and used the same frame/filter for years without replacing anything but the pillow or headgear...
I have never ever experienced what you experienced. So while you have a problem, not everyone else in the world has that problem.
Believe what you want to believe but it isn't common and ResMed didn't design the diffused venting to increase sales in this way.

You get to state your personal opinion here....as do I and my opinion differs widely from yours. I am not wanting to engage or discuss.
Just stating an alternate viewpoint for others to read and they get to form their own opinion.

Hi Pugsy,
The first bit is my person opinion. The second is the content from a link.

Look, I see the same issue with my N30 as I did with my p10. I wash/toothbrush scrub my mask every week. Still eventually had the issue that I'd had with the p10.

I ams also not really looking to engage/discuss. I know my experiences. All I'm doing is posting about my experiences AND provide a link that explains my issues. The post is now archived here and might be of benefit to anyone experiencing similar issues (as all of us are here to help as well as learn). Cheers.
Richard

[Pugsy]

The apneaboard stuff...doesn't sway me one bit. Sorry. It is also personal opinion in my book.
No facts...just thoughts and opinions at a forum that doesn't even allow the word cpaptalk to be type much less a link to anything here.
The assertion that this was a planned issue by ResMed just to increase sales....ridiculous...and just another crazy conspiracy theory.

Now if some independent lab actually published real research data...I might look at that.

Have a nice day.

[jimbud]

I wash/toothbrush scrub my mask every week.

The vent mesh will get restricted somewhat in time. (my experience comparing a several month used one with a new one held up to a bright light)

Get a water pic, wash as usual, then blast it with the water pic.
Good as new. My personal experience.
No need to freak out.
Just clean it properly.

You might have more "stuff" in your exhale than most.
Maybe?

Now my post has been archived as well.

JPB

[Dog Slobber]

I ams also not really looking to engage/discuss. I know my experiences. All I'm doing is posting about my experiences AND provide a link that explains my issues.

Yeah, why would one ever want to engage or discuss things.

That might accidentally lead to actually changing one's opinion, should more information be presented.

[chunkyfrog]

I too have been having NO PROBLEMS with the Airfit 10.
I have been using the Airfit 10 nasal pillows mask for several years.
I am not a physician, but I have been successfully using cpap for over TEN YEARS.
Worry alone can make one ill--nobody is immune.
---maintain perspective.

[Julie]

Last thing Mr. Nosey - just as long as we're here - was there a reason you titled your note ALL IN CAPS? I must assume since you are a doctor (aren't you?) that you use the internet a lot, and have done so for years, so... why haven't you yet learned that Caps signifies yelling at people? Or was that your intention? Why? Do you think it's more effective? That we must be hit over the head before reading your note in case we miss something (any more than we 'miss' all the other notes)?

Not a great way to win friends, etc... never mind convincing anyone to listen to what you say.

[Mr Nosey]

Last thing Mr. Nosey - just as long as we're here - was there a reason you titled your note ALL IN CAPS? I must assume since you are a doctor (aren't you?) that you use the internet a lot, and have done so for years, so... why haven't you yet learned that Caps signifies yelling at people? Or was that your intention? Why? Do you think it's more effective? That we must be hit over the head before reading your note in case we miss something (any more than we 'miss' all the other notes)?

Not a great way to win friends, etc... never mind convincing anyone to listen to what you say.

My mistake...it was a copy/paste of a post from another site. Definitely see your point about the CAPS. Quickly composed what I had to say and then copy/paste of title of another thread. Was very busy this a.m. Thx for the response..

[jimbud]

In case anyone wants to read even more whining about the P10 (including more Mr. Nosey with cameos by Pugsy, palerider, jnk and supporting cast):

viewtopic/t174159/Problems-with-airflow ... l?start=30

A great way to waste more time!

JPB

Ho Hum.