Unvented Masks and Accuracy of Mask Leak Data

[Dov Ber]

Hi all. I'm new here, and though I've spent a bit of time reading posts do forgive me if I'm not all the way up on the forum etiquette yet.

So, I recently started CPAP treatment using a full face mask just about two weeks ago. And because my sleep apnea has "mixed features" - i.e. both obstructive and central - my doctor decided that I ought to use an non-vented mask, since re-breathing a little extra CO2 supposedly helps with the central component. Anyhow, I'm using the Phillips Respironics "sleep mapper" app to track my data, and the numbers look good (AHI averaging 1.5 and 3 is the highest it's gotten). They look too good, actually. Way better than they seem like they should considering that I'm just not feeling much more energetic or less sleepy than I did before I started treatment. In particular I've noticed that there have been a few nights where I've woken up several times from mask leaks irritating my eyes or skin or whatever, and then when I check the app the next day it lists my "mask fit" as 100%. Is it possible that the way the machine gathers the data is calibrated for a vented mask and so my numbers are inaccurate? Maybe I just have long months of catching up on sleep debt or rebounding or whatnot to look forward to and really everything is going fine. That would be cool. But, I'm curious to know if anyone else has used a non-vented mask and noticed a discrepancy between their data and their perceived experiences.

[LSAT]

I don't know what you mean by unvented. The FF mask you show in your profile is definitely vented.

[Bobby269]

When I used the quattro FX mask it certainly vented. Next time you have your mask on and machine on. Feel the air coming out near where the hose connects to the mask. There is a vent in that area .

[JDS74]

Dov Ber,

It is not clear to me what you and your doc mean by the term "non-vented mask."
If your mask is the Quattro FX FFM, then it is vented.
If you use a FFM and have the vent sealed and you don't have major mask leaks, there is nowhere for the exhaled air to go and no good way for new oxygen to get to you. Its like breathing into a paper bag sealed around your nose and mouth. It won't be long before you're in real trouble.

So, could you elaborate on the "non-vented" comment?

[buran]

I guess what Dov Ber is talking about is EERS: “Treatment of Positive Airway Pressure Treatment-Associated Respiratory Instability with Enhanced Expiratory Rebreathing Space (EERS)”. See figures 1 and 2:
ncbi.nlm.nih.gov/pmc/articles/PMC3014237/
Basically, it consists of a nonvented mask, "dead space" tube (optional), and Respironics whisper swivel exhalation port (part 332113).
Any vented mask can be transformed into a nonvented (I use F&P Simplus) by blocking vent holes with silicone earplugs or (much better) 3M Microfoam surgical tape.

[robysue]

Dov Ber,

As others have pointed out, there is some confusion about what you mean by an unvented mask.

What I want to address is this:

Anyhow, I'm using the Phillips Respironics "sleep mapper" app to track my data, and the numbers look good (AHI averaging 1.5 and 3 is the highest it's gotten). They look too good, actually. Way better than they seem like they should considering that I'm just not feeling much more energetic or less sleepy than I did before I started treatment. In particular I've noticed that there have been a few nights where I've woken up several times from mask leaks irritating my eyes or skin or whatever, and then when I check the app the next day it lists my "mask fit" as 100%.

Sleep Mapper gives extremely limited data, and the only thing that Sleep Mapper "mask fit" data means is that the PAP machine did not score any official Large Leaks during the night.

Most leaks are NOT official Large Leaks. The kind of mask leaks you're talking about are common place, but they seldom ever are large enough to be flagged as a Large Leak. The only leaks that get flagged as Large Leaks are those that are large enough to make it difficult for the machine to maintain the appropriate pressure in your upper airway.

I've been using a PR BiPAP for over 3 1/2 years now. And I've had plenty (small) irritating leaks and some occasional mouth breathing all along. But I've had less than 10 leaks that were LARGE enough to get scored as an official Large Leak. And my longest official Large Leak lasted less than 10 minutes out of a night that had about 5 hours of usuage, which is about 3% of the night. So on my worst night ever for official Large Leaks, Sleep Master would have reported a mask fit of about 97%.

As for why you're still not feeling any better: It takes time. Some people feel better almost immediately. Others start to feel better in a few weeks to a couple of months. Some of us don't feel much better until we've been PAPing for 6-12 months. And a few unlucky people never notice much improvement in how they feel from day to day even though their numbers look good. The medical community really has no good ideas on why a some people take so long to start feeling better.

[Dov Ber]

Sorry all. I guess this non-vented thing is more unusual than I thought. From what I'm told, each mask style can be made in a vented and non-vented version. So, it's not a matter of the mask model.

It's helpful to know that a leak has to be pretty large to 'register' on the app. I hope the data that's sent via modem to my doctor has more detail than what shows up on the app. Maybe she'll have some insight.

[Dov Ber]

I guess what Dov Ber is talking about is EERS: “Treatment of Positive Airway Pressure Treatment-Associated Respiratory Instability with Enhanced Expiratory Rebreathing Space (EERS)”. See figures 1 and 2:
ncbi.nlm.nih.gov/pmc/articles/PMC3014237/
Basically, it consists of a nonvented mask, "dead space" tube (optional), and Respironics whisper swivel exhalation port (part 332113).
Any vented mask can be transformed into a nonvented (I use F&P Simplus) by blocking vent holes with silicone earplugs or (much better) 3M Microfoam surgical tape.

Yes, if I'm decoding the medical jargon from that article right, that does seem like what my doc told me. She said it's an "off label" treatment but can be effective for treating OSA with some mixed central features. In between my mask and the regular hose I do have a small bit of extra tubing and then some hard plastic parts with a one-way valve that lets the air from the machine flow upward but doesn't let all the air I exhale flow back down. It makes a kind of dramatic "pop" sound if I exhale too forcefully.

[buran]

Dov Ber,
Do you have a non vented version of Quattro FX?
http://www.resmed.com/us/en/hospital/pr ... ented.html

[robysue]

It's helpful to know that a leak has to be pretty large to 'register' on the app. I hope the data that's sent via modem to my doctor has more detail than what shows up on the app. Maybe she'll have some insight.

The data that's sent to the doc by the modem might show a bit more detail, but unless the PR online data tools are substantially better than the Resmed ones, the doc won't have much more data than you do: The doc will see a statistical summary of the efficacy data: The AHI will be broken down into OAI, HI, and CAI, and the leak data may include the average leak rate as well as the fact that there were no Large Leaks detected.

The thing is: Your machine does record full detailed data of every breath you take all night long when you use the thing. It records this data on the SD card that is currently hidden by that dang modem attached to your modem. And software exists that allows your doc (and YOU) to look at that data, on a breath by breath basis if desired.

The DME (and doc) may use a program called Encore Pro to download detailed data from every night you use the PAP; if they want to, they can also download and look at the trace of your breathing for the entire night for the last night in the down load. You can get your hands on Encore Pro if you really want to, but there's a free program called SleepyHead that was written by one of the forum members here that will allow you to see everything that shows up in Encore Pro, along with all the wave flow data. You can download SleepyHead from http://www.sleepfiles.com/SH/ if you want.

[archangle]

Sorry all. I guess this non-vented thing is more unusual than I thought. From what I'm told, each mask style can be made in a vented and non-vented version. So, it's not a matter of the mask model.

Neat. Let us know how it works for you.

I hope your doctor warned you not to tinker with the setting and remove the vent. You'll die without the vent. Also be sure to never give the mask to someone else.

Forget the sleepmapper and get SleepyHead or Encore Basic. Compared to them, Sleepmapper is like trying to drive your car with a frosted window with a tiny spot scraped clear.

[JDS74]

Here is an interesting article on the use of this type of mask modification.

http://www.researchgate.net/profile/Dea ... 738812.pdf