Issues about using a mask without the anti-asphixia valve??

Hi, I have been using a Fisher & Paykel FlexiFit HC431 for a while without the anti-asphixia valve. I use a ResMed S9 Autoset.

The reason is that after a short time, the valve wasn't working properly. It seemed that because the humidity the flipping part of the valve stuck in the wall of the valve tube, letting the air coming from the cpap pump to the exterior and not in to the mask. Every night, this happened and there was a lot of noise from the air coming out (I guess it is a good signal when you are having some trouble not getting air) that woke me up several times, and either i got up to clean and fix the position of the valve's flipping part or took out the mask.

This problem with the valve happened also with other two masks I tried, the mirage liberty and the hybrid. I don't know whether is the local humidity (I live in Guatemala City, 1,500 meters above sea level, not so humid not so dry). I stopped using those masks mainly because of leakings, but still the valve issue happened repeatedly.

So one night, I was so tired of been woke up, I tried to use the mask without the valve, and it worked. I thought that in case of asphixia, I could wake up myself or took the mask myself, because I am 40 years odl and have a good health, I don't drink or use any substance that would impair me from waking up.

Since then, I haven't used the anti-asphixia valve and haven't had any problem with the mask.

Well, but still I have doubt whether there is a serious issue about doing this.

1) Is it evidence this would affect my therapy?

2) Would the measures taken by the machine be affected?

3) When and why would the anti-asphixia be useful?

Thanks in advance,

Antonio

Welcome to the forum, Antonio. I don't know the answers to your questions, but I can bring it back to the first page so someone else can comment.

If the power goes out, you DIE. How's that for an issue?

Without the anti-asphyxia valve, if the machine quits blowing air, you may die unless you wake up and take off the mask. That's why all full face masks have to have anti-asphyxia valves.

You might wake up, but sometimes, the slowly increasing CO2 levels can render you unconscious without you noticing anything is happening. Slowly increasing CO2/low O2 levels kill people in industrial settings all the time. Look up "confined space entry".

If the power goes out, the machine breaks, or you just pull the other end of the hose from the machine, the air you exhale stays in the hose. You breathe the air out into the hose, then inhale it back into your lungs. O2 levels drop. CO2 levels rise. You can die. There will be a little bit of air leakage out of the vent holes in the mask, but they're intended to work with a PRESSURIZED mask. They won't leak enough CO2 to be safe if there's not pressure on the mask. There will be some mixing of fresh air in the hose but, you will mostly be pushing stale air down the hose and then sucking it back into your lungs.

It's like putting an inflated plastic bag over your head and breathing in and out of it. You eventually use up all the air.

In the case of the CPAP machine, there are some holes in the bag, but it's iffy whether enough fresh air will come in to keep you alive.

archangle wrote:Without the anti-asphyxia valve, if the machine quits blowing air, you may die unless you wake up and take off the mask. That's why all full face masks have to have anti-asphyxia valves.

That sounds kind of scarry! Is that the small plasic looking thing that is in the swivel tube that the air hose connects onto? Do those valves ever stick?

Roger2 wrote:

archangle wrote:Without the anti-asphyxia valve, if the machine quits blowing air, you may die unless you wake up and take off the mask. That's why all full face masks have to have anti-asphyxia valves.

That sounds kind of scarry! Is that the small plasic looking thing that is in the swivel tube that the air hose connects onto? Do those valves ever stick?

It's in different places on different masks. I think that's where it is on the Quattro FFM. You can usually see a little flapper that blocks off airflow.

If you want to test it, mask up, unplug the hose at the machine end, and put your thumb over the end of the hose. You should be able to breathe more or less normally if the valve's working correctly. There should be very little resistance to a normal rate of breathing.

Note that ONLY full face masks or other masks that cover your mouth normally have anti-asphyxia valves.

archangle wrote:If the power goes out, you DIE. How's that for an issue?

Without the anti-asphyxia valve, if the machine quits blowing air, you may die unless you wake up and take off the mask.

Then this is an issue for everyone using a nasal mask or pillows and taping, and even for people using a nasal mask/pillows and a chinstrap. I wonder what the odds are of someone not waking up due to feeling they can't breathe. I worry about my son who is sleeping with a nasal mask and a chinstrap... I'm thinking of buying some kind of uninterruptible power supply for his CPAP.

https://www.cpap.com/productpage/relian ... light.html

SU, I bought this handy gadget which I plug in close to my bedside which will sound an alarm and wake ME if the power goes out. It also doubles as a flashlight. It's happened twice and woke me immediately so I could take Mike's mask off. I didn't give it a chance to see how long it would have taken him to wake up on his own! Both times the power came back on in a few minutes.

SleepingUgly wrote:

archangle wrote:If the power goes out, you DIE. How's that for an issue?

Without the anti-asphyxia valve, if the machine quits blowing air, you may die unless you wake up and take off the mask.

Then this is an issue for everyone using a nasal mask or pillows and taping, and even for people using a nasal mask/pillows and a chinstrap. I wonder what the odds are of someone not waking up due to feeling they can't breathe. I worry about my son who is sleeping with a nasal mask and a chinstrap... I'm thinking of buying some kind of uninterruptible power supply for his CPAP.

I can still open my mouth and breathe despite the chinstrap. It just doesn't flop open on it's own. I guess there's a theoretical risk you won't open your mouth, though.

Yes, mouth taping with a nasal mask should have the same level of risk you do with a full face mask with no anti-asphyxia valve.

When you say you use the mask without the anti-asphyxia valve, what do you mean? Do you mean you remove the flap that opens when the machine is off, but closes when air is flowing? Or somehow block the valve from opening? Or?? I don't think on most masks it is possible to actually remove the valve... but I'm not familiar with the details of your mask.

I ask because the answers here pertain only if you mean that you block the valve... if you have actually removed the flap, it means that air is escaping from the hole all of the time when the air is flowing, in which case you have rendered your mask leak rate far beyond the intended rate. A high leak rate can compromise the effectiveness of the treatment. I see you have a ResMed AutoSet S9, so you should be able to check your leak rate... the quick way is to view the "Info" screen--if you get the frown face, your leak rate is too high. If you get the smiling face, your leak rate is within accepted parameters by Resmed, but still may not be optimal. Better yet, get the software and check all of your info (AHI, leak, etc) to evaluate whether your treatment is effective (search the forum for Rescan).

For what it's worth, it's highly unlikely that you will die because of not waking up to the air not flowing... you have built-in survival instincts that would wake you long before you needed to... I can only think that if it did happen, you'd have taken very serious sleep meds or sedation beforehand, and that's not likely to happen to the average Cpap user.

jmelby wrote:When you say you use the mask without the anti-asphyxia valve, what do you mean?

For the mask he's using, the anti-asphyxia valve is a separate piece. It attaches to the end of the swivel elbow between the mask and the hose. I suppose if you take it off, you might be able to put the hose onto the elbow, even though it's not really designed to fit that way. In this case, there will be no extra leakage, just the air flowing out the exhaust vent.

Julie wrote:For what it's worth, it's highly unlikely that you will die because of not waking up to the air not flowing... you have built-in survival instincts that would wake you long before you needed to... I can only think that if it did happen, you'd have taken very serious sleep meds or sedation beforehand, and that's not likely to happen to the average Cpap user.

One would think it works that way. However, in industrial environments, one of the big bugaboos is "confined spaces," defined as areas without sufficient natural airflow to maintain sufficient oxygen. This can be tanks, tunnels, etc.

Healthy, fully awake grown men often walk into such spaces, lose consciousness due to low O2 concentrations and die. Sometimes two or three people at a time. They often don't realize anything is wrong before they lose consciousness. Sometimes, someone goes in to rescue them and dies, too. Supposedly, this is simply from lack of oxygen, NOT from chemical fumes.

At any large industrial company, part of your yearly mandatory safety lecture is where they try to scare the hell out of you about confined spaces. If you walk around any such factory, you will see big warning signs saying something like "Confined space #123. Permit required before entry." I've been suitably hellscared multiple times.

I have a low tolerance for corporate BS. I have a low tolerance for overly cautious plant safety types. I've fought stupid safety guys many times. I do strongly believe in the risks of suffocation in industrial confined spaces. There are too many graves of victims to ignore.

Google "confined spaces" and read up on it.

Maybe low O2 from a failed CPAP machine is somehow different. Maybe you will reliably wake up. Since all full face masks have anti-asphyxia valves, apparently the government and/or machine manufacturers don't think so. Or maybe they're worried about drugged, drunk, or otherwise impaired patients.

I don't see why a fully awake, healthy person will fall unconscious without warning in a low O2 environment, but a sleeping CPAP user won't.

It's also important to realize that when your CPAP shuts down in this situation that you can still inhale and exhale normally. It's not like someone clapping a hand over your mouth and nose and trying to strangle you. Your lungs still inflate and deflate. It's just that you get gradually decreasing O2 concentration.

Let's also not forget that many of us apneacs get severely depleted O2 saturations and don't wake up. Or sit there not breathing during a 2 minute apnea before we wake up. One would think that if someone shut off your air for even a minute, you're wake up, but we often don't.

archangle wrote:
If you want to test it, mask up, unplug the hose at the machine end, and put your thumb over the end of the hose. You should be able to breathe more or less normally if the valve's working correctly. There should be very little resistance to a normal rate of breathing.

OK, that worked. The only resistance was when I exhaled strongly but I would never exhale that forcefully nor do I believe I would do that in my sleep unless for some reason I awoke in a panic mode.

Thanks for the information, I am still a little paranoid about using this machine,

archangle wrote:It's also important to realize that when your CPAP shuts down in this situation that you can still inhale and exhale normally. It's not like someone clapping a hand over your mouth and nose and trying to strangle you. Your lungs still inflate and deflate. It's just that you get gradually decreasing O2 concentration.

Could that happen if you have external O2 bleeding in at the connection where the airhose attaches to the cpap machine? I have 4 ltrs comming in at that point.

A confined space is an area big enough to get into that is not designed for occupancy. There is a difference between entering a confined space and entering your bedroom.

Continuous re-breathing air can cause problems and it is not clear if the vents in the various masks allow enough air exchange to contribute to re-breathing. If a person had access to a meter that reads O2 levels, that would be easy to check out, but I am not sure if anyone has actually done that.

Having recently experienced a power outage I can tell you that I immediately noticed the change in the feel of the mask and woke up. Usually there is air blowing into the mask and it tends to float on your face. When the power goes out, the mask sucks into your face with each breath and becomes more uncomfortable to wear. I simply took my mask off and went back to sleep. An hour later when the power came back on, I was aroused by the noise of the machine blowing air and put my mask back on again and went back to sleep again. Not the most restful nights sleep, but OK.

If you were drugged or unconscious, you may not wake up, but then you may not be in a position to put the mask on in the first place. If you are taking care of someone, that is different. To get an idea of how well your mask works, set your pulse oximeter to alarm at 90% oxygen, put the pulse oximeter on, then put your mask on and don't turn on the machine. If you notice your O2 levels dropping, you could get into trouble during a power outage. If you O2 levels remain stable, that would indicate that there is enough air transfer to keep you going.

All in all, an anti-asphyxiation valve is good to have and if your set up doesn't have one further testing is needed to determine how much danger you would be in if the power fails.

I think the change in mask fit would wake most people up, but there is always the exception.