Traded OSAs for CAs during home APAP trial - What next ?

[Stom]

I think it's worth seeing if removing EPR can bring you closer to the goal. The Enhanced Expiratory Rebreathing Space (EERS) stuff makes a lot of sense for individuals that do not have central sleep apnea in diagnostic tests, but develop complex apnea with therapy.  The risk of oxygen desaturation is actually pretty low. Your tidal volume average of 440 mL with a dead-space of 60-100 mL would likely restore respiratory drive to background levels while eliminating OA at relatively low pressure.  If you decide to experiment with it, just buy the $20 swivel/vent and attach it between the CPAP tube and your N20 hose for 70 mL of dead space.  If that works, then fine. If you need more, then a 6-inch section of corr-a-flex cpap hose is pretty cheap (order at thee time to save shipping), and provides another 58 mL.  You should not damage your mask vent, just tape over the the vent holes temporarily.  The pressure and lack of apnea maintains O2 safely, while the dead space prevents excess purging of CO2.  Excess CO2 will cause hyper-ventilation and prevent hypoxia, so the natural feedback loop prevents low oxygen levels.

Your first step in that goal is to eliminate EPR.  Only go to EERS if that fails to resolve CA.  EERS is experimental, even in the case of Firefox and is not an approved FDA application, but it makes a ton of sense.  If I was in your place I would try it, but I'm a risk-taker, and you should follow your own judgement.  I'm pretty excited about the possibility of this technique avoiding ASV in some cases.

If I do wind up buying an APAP I will definitely try out turning off the EPR and seeing what that does for me. I'm curious about the EERS info as something to put on the back burner for later consideration, but I'd like to ask about it now since it has come up. I found this:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3014237/

Which seems to be where the term EERS originated and lays out their experimental set up:

"The essential components are available and FDA approved; the assembly and use is off-label. A non-vented mask such as the ResMed Mirage non-vented (top) or a mask that can be made non-vented (such as the Breeze, Activa, Quattro, Liberty, Swift) is required. Other essential components are (from left to right) mainstream CO2 sensing, segments of 22 mm tubing that is the re-breathing space, and the Whisper Swivel valve (Respironics)."

   

The set up foxfire posted has an extra set of blue tubing between the safety valve and the PAP machine, labeled as EERS tubing, and then another valve, which confuses me. I'd think just the dead space between the mask and the safety valve would be the EERS deadspace.



Is the blue tubing between the safety valve and the pap supply just for convenience and to add a swivel connection? I'm not understanding the dual valve setup in the slide posted by foxfire.

Also, is the known intentional leak rate of the CO2 washout vent of the nasal mask used for any other calculations by the APAP that would affect auto pap? I know that the intentional leak rate graph at various pressures is used as the baseline to detect mask leak rate, so sealing the intentional leak will cause unintentional mask leaks to be under reported, but other than that, would there be any effect on the resmed's functions?

[Sleeprider]

Good find on the article which shows this approach has a lot of promise in improving objective results as measured in clinical polysomnolgrapy and does not cause tachypenia (hyperventiltion). or tachycardia (rapid heart rate at 100 to 150 mL of EERS.

In the image, the blue tubing is standard 22 mm CPAP tubing referred to as corr-a-flex. It is sold in 100 foot rolls pretty inexpensively, and can be separated into 6-inch segments that I have calculated should have about 58 mL of dead space (see the other thread). Basically, the EERS requirement of 100 to 150 mL is met by using a standard nasal tube and one of these 6-inch segments. The swivel valve on the end that connects to the CPAP tube provides the venting function that usually occurs at or near the mask. So when you exhale, the mask tube and corr-a-flex tube fill with expired air (less than 150 mL). Pressure is maintained during expiration by the CPAP, and any excess expired air is vented at the swivel vent. When inspiration begins, the first, up to 150 mL of air is re-breathed, but most people have inspiratory volumes from 380 to 650 mL, so fresh air is always provided. The trick is to size the EERS to correspond to tidal volume, so smaller Tv would use less EERS space, and higher volumes would use more EERS space. That math has not been worked out or proposed as part of this formula.

TMI. I know it sounds a bit esoteric and technical, but it makes total sense on the whole. You just happen to be the unfortunate member that arrived with the complex apnea symptoms at the moment I have started to put this puzzle together.

[Stom]

Good find on the article which shows this approach has a lot of promise in improving objective results as measured in clinical polysomnolgrapy and does not cause  tachypenia (hyperventiltion). or tachycardia (rapid heart rate at 100 to 150 mL of EERS.  

In the image, the blue tubing is standard 22 mm CPAP tubing referred to as corr-a-flex. It is sold in 100 foot rolls pretty inexpensively, and can be separated into 6-inch segments that I have calculated should have about 58 mL of dead space (see the other thread). Basically, the EERS requirement of 100 to 150 mL is met by using a standard nasal tube and one of these 6-inch segments.  The swivel valve on the end that connects to the CPAP tube provides the venting function that usually occurs at or near the mask.  So when you exhale, the mask tube and corr-a-flex tube fill with expired air (less than 150 mL). Pressure is maintained during expiration by the CPAP, and any excess expired air is vented at the swivel vent.  When inspiration begins, the first, up to 150 mL of air is re-breathed, but most people have inspiratory volumes from 380 to 650 mL, so fresh air is always provided.  The trick is to size the EERS to correspond to tidal volume, so smaller Tv would use less EERS space, and higher volumes would use more EERS space.  That math has not been worked out or proposed as part of this formula.

TMI. I know it sounds a bit esoteric and technical, but it makes total sense on the whole.  You just happen to be the unfortunate member that arrived with the complex apnea symptoms at the moment I have started to put this puzzle together.

Thanks :-)

I think I get the basic idea of providing rebreathing dead space to increase CO2 by a calculated volume as shown in "Treatment of Positive Airway Pressure Treatment-Associated Respiratory Instability with Enhanced Expiratory Rebreathing Space (EERS)". They use an amount of dead space between the non-vented mask and the valve, space they call "EERS". That makes sense to me:

Mask --- dead space -- whisper swivel valve -- pap supply

But the foxfire nasal mask set up has two valves:

Nasal mask --- dead space -- "safety valve" -- dead space --- "whisper swivel valve" -- pap supply

That I don't get. Why two valves? Is it a typo? Is the label that says "whisper swivel valve" actually just a "swivel" with some corr-a-flex connecting it to the safety valve to add a swivel to the set up? The corr-a-flex between the "safety valve" and the "whisper swivel valve" is specifically labeled as "EERS" tubing, suggesting that is is a functional part of the EERS dead space as opposed to just bit of flexible tubing to allow a swivel connector to connect to the pap supply . So I'm confused.

[trance]

Thanks :-)

I think I get the basic idea of providing rebreathing dead space to increase CO2 by a calculated volume as shown in "Treatment of Positive Airway Pressure Treatment-Associated Respiratory Instability with Enhanced Expiratory Rebreathing Space (EERS)". They use an amount of dead space between the non-vented mask and the valve, space they call "EERS". That makes sense to me:

Mask --- dead space -- whisper swivel valve -- pap supply

But the foxfire nasal mask set up has two valves:

Nasal mask --- dead space -- "safety valve" -- dead space --- "whisper swivel valve" -- pap supply

That I don't get. Why two valves? Is it a typo? Is the label that says "whisper swivel valve" actually just a "swivel" with some corr-a-flex connecting it to the safety valve to add a swivel to the set up? The corr-a-flex between the "safety valve" and the "whisper swivel valve" is specifically labeled as "EERS" tubing, suggesting that is is a functional part of the EERS dead space as opposed to just bit of flexible tubing to allow a swivel connector to connect to the pap supply . So I'm confused.

I 'think' this is addressed in post #18 of the thread http://www.apneaboard.com/forums/Thread-...eep?page=2  

This EERS stuff is both interesting and encouraging.

[Stom]

I 'think' this is addressed in post #18 of the thread http://www.apneaboard.com/forums/Thread-...eep?page=2  

This EERS stuff is both interesting and encouraging.

Thanks for the link.

It looks like my confusion could be because these are two different kinds of valves, but aren't explicitly labeled that way because their use is understood by professionals.

I now take it that the first valve (the one near the mask) is an anti-asphyxiation valve - a valve that acts like a sealed tube so long as there is positive pressure in the system, regardless of flow direction, but seals the connection to the pap supply and opens the opens vents to the room air for both inspiration and expiration when pap supply pressure is lost. And that the second is an exhalation valve that acts like a tube during inspiration, letting air in from the pap supply, but seals off the pap supply and vents expiration out to the room when flow is reversed.

So I take it the 2010 EERS study didn't use an anti-asphyxiation valve on the full face mask for safety because it was an attended study using a lab ventilator system and used real-time CO2 monitoring. A home user, OTOH, with an unvented full face mask would need both the anti-asphyxiation valve and the separate exhalation port valve (PAP machine is not a closed system, though, so you can still suck air through the supply tube even if the machine is off, and I'd guess the exhaust vent will still prevent 100% C02 rebreathing even if the PAP is off). But you would not necessarily need an anti-asphyxiation valve even for an unvented nasal mask since the mouth is not obstructed and the CO2 reflex would cause the user to just breathe through their mouth.

[foxfire]

I 'think' this is addressed in post #18 of the thread http://www.apneaboard.com/forums/Thread-...eep?page=2  

This EERS stuff is both interesting and encouraging.

Thanks for the link.

It looks like my confusion could be because these are two different kinds of valves, but aren't explicitly labeled that way because their use is understood by professionals.

I now take it that the first valve (the one near the mask) is an anti-asphyxiation valve - a valve that acts like a sealed tube so long as there is positive pressure in the system, regardless of flow direction, but seals the connection to the pap supply and opens the opens vents to the room air for both inspiration and expiration when pap supply pressure is lost. And that the second is an exhalation valve that acts like a tube during inspiration, letting air in from the pap supply, but seals off the pap supply and vents expiration out to the room when flow is reversed.

So I take it the 2010 EERS study didn't use an anti-asphyxiation valve on the full face mask for safety because it was an attended study using a lab ventilator system and used real-time CO2 monitoring. A home user, OTOH, with an unvented full face mask would need both the anti-asphyxiation valve and the separate exhalation port valve (PAP machine is not a closed system, though, so you can still suck air through the supply tube even if the machine is off, and I'd guess the exhaust vent will still prevent 100% C02 rebreathing even if the PAP is off). But you would not necessarily need an anti-asphyxiation valve even for an unvented nasal mask since the mouth is not obstructed and the CO2 reflex would cause the user to just breathe through their mouth.

Yes, you've got it. One minor detail is that the Whisper exhalation valve continuously vents a fixed amount of air flow, depending on pressure of course, it doesn't close during inspiration and open during exhalation. So it acts in the same way as the vent holes in a mask which also vent continuously.

[Sleeprider]

Couldn't have said it better. Thanks for that!

[foxfire]

In the image, the blue tubing is standard 22 mm CPAP tubing referred to as corr-a-flex. It is sold in 100 foot rolls pretty inexpensively, and can be separated into 6-inch segments that I have calculated should have about 58 mL of dead space (see the other thread). 

I was able to buy a 4' section of corr-a-flex on ebay for $7. More than enough for EERS purposes.

[Stom]

Yes, you've got it. One minor detail is that the Whisper exhalation valve continuously vents a fixed amount of air flow, depending on pressure of course, it doesn't close during inspiration and open during exhalation. So it acts in the same way as the vent holes in a mask which also vent continuously.

Thank you. Even the Phillips ventilation catalog doesn't actualy specify it's exact function. (There must be some listing exact specifics like the vent rate at various pressures somewhere, but I couldn't find it.) Having it labeled as a "valve" on one of the pictures made me assume it was a valve of some sort rather than a vent.

[Stom]

Just back from the RT. To no one's surprise, I am now the proud owner of a shiny new RX for an APAP...:

APAP 7-12
EPR 1
Ramp start 5

She said that if we simply toss out out the bad night on the 7th as anomalous, this week looks much better. And that their metric for sending people off to the attended titration sleep lab is 15 AHI. So, I'm between the under 5 and the 15 or over.

I told her specifically that I'm not sleeping better under treatment than I was without treatment, and that I wake up more frequently under treatment. She believes that it will take up to 3 months of compliance to actually sleep better, to get used to PAP.

The big data study I cited earlier does seem to support her impression, but only by a slim margin 55% get better to 45% who don't or get worse.

I am considering filling the RX at my expense (no DME coverage) and I'm look in to pricing, but I gotta say 3 months of compliance all while possibly sleeping worse strikes me as a big challenge...but I'm out of "free" titration time to see if I'll continue to improve using their machines. So, dunno. Looking forward to sleeping without the APAP in the meantime...which sort of says something to me....