Rebreathing air

[nr224]

Hello all, new CPAP user here. I've spent pretty much all night trying to sleep with this thing. It's now 4AM and I'm tempted to sleep without it.

Problem is, I feel like I'm suffocating on this thing, but NOT because of not having air (I have the min pressure set to 6.0 with ramp off, so I get air fine), but because it feels like I'm breathing the same air. Other threads described it like breathing into a paper bag.

I disconnected my nasal pillow to check, and I don't think its microscopic vents are sufficient for exhaling -- I don't feel much air coming out of the pillow when I exhale (air is forced back up the tube -- even after artificially sealing the tube). I absolutely hate it and I need fresh cold air... preferably a vent that prevents air from going up the tube. Is there any nasal pillow like that? Thanks!

[Pugsy]

Welcome to the forum.

For now....just remove the diffuser portion so that the air will exit more forcefully and see if that resolves your issue.
If it doesn't...try minimum pressure of 7 and see if that helps. The diffuser filer is optional...it pops right off.

[JimW159]

My experience with the Brevida mask mirrors Pugsy's recommendation. While the diffuser does just what it says: it diffuses the exhalation, its removal seems to relieve what seems like a slight obstacle to exhalation and allows a much more direct stream of air from the ports. You may well find it preferable though your bed partner may be impacted as you may be because it is slightly louder.

[Stom]

There is no need to remove the diffuser, though there is no harm in doing so. The Brevida is engineered to have a safe intentional leak rate with the diffusion on to provide plenty of CO2 washout. The intentional leak rate of the Brevida *with* the diffuser on is actually higher than the intentional leak rate of the ResMed P10 nasal pillows. Removing the diffuser will provide only a minor increase in intentional leak rate.

Both the P10 and the Brevida share a feature that confuses new users to these masks, which is that the passive vent airflow is diffused, and often warm, making it very hard to detect the vented airflow when you put your hand up to it. A more concentrated flow of undiffused air feels like more flow to us, especially if we are used to airflow that we can easily feel from masks with undiffused vents. I think diffused air vents can confound our expectations and make people think they don't work even though they do.

I've superimposed the intentional leak rate graphs of the Brevida and the P10, adjusting the X and Y scales to match:

P10-vs-Brevida.png (96.25 KiB) Viewed 20095 times

Edit:

I'm still new to PAP. Initially, breathing into pressure made me feel like you did no matter what mask I wore, even though the masks are venting continuously at a carefully engineered rate to washout CO2 quickly. Chances are you just need to get used to the unusual feel of PAP. Turning on the EPR feature may help the feeling of not venting.

[Voxhumana]

Yes, I experience that feeling as well. I use the nasal mask, but not the pillows. I believe the device works by measuring the back pressure from your exhalation, each breath. By that measure, it knows whether you are in a sleep apnea episode, and subsequently pushes more air into the tube under pressure, which opens your obstructed airway. Anybody else have a better description?

[Stom]

Yes, I experience that feeling as well. I use the nasal mask, but not the pillows. I believe the device works by measuring the back pressure from your exhalation, each breath. By that measure, it knows whether you are in a sleep apnea episode, and subsequently pushes more air into the tube under pressure, which opens your obstructed airway. Anybody else have a better description?

That's what I thought, but it turns out to be wrong. Once you are in a fully obstructed apnea, APAP machines can't force your airway open. An APAP isn't a toilet plunger. Instead, the APAP waits until you start breathing on your own and open the airway by changing your body position and/or tighten the muscles that hold your soft tissues from blocking your airway. Then the APAP may increase the pressure to help prop open your airway with pressure. The APAP will only increase pressure during an event if the airway is only partially obstructed, such as during a flow restriction.

[palerider]

Yes, I experience that feeling as well. I use the nasal mask, but not the pillows. I believe the device works by measuring the back pressure from your exhalation, each breath. By that measure, it knows whether you are in a sleep apnea episode, and subsequently pushes more air into the tube under pressure, which opens your obstructed airway. Anybody else have a better description?

Your belief is incorrect. It doesn't measure back pressure, it doesn't *ever* increase pressure to open the airway. It waits till the airway is open again, then raises pressure to keep it open.

The device monitors the flow of air.
https://www.youtube.com/watch?v=-gie2dhqP2c

[Stom]

It doesn't measure back pressure

I think I'd clarify that the machine does measure pressure, as can be seen in the mask pressure - time graph, but as you note, that monitored pressure isn't how the APAP scores events such as apneas, hypopneas or flow restrictions, rather the machine examines the flow rate curves over time.

[nr224]

I see, thanks! So, how do I remove the diffuser?

That graph is very revealing. It's good to know -- maybe the hot air I breathe out warms up some of the air I breathe back in, making me think that I'm not getting enough oxygen, even if I am. I'll have to put on a pulse ox and check overnight.

[Stom]

I see, thanks! So, how do I remove the diffuser?

That graph is very revealing. It's good to know -- maybe the hot air I breathe out warms up some of the air I breathe back in, making me think that I'm not getting enough oxygen, even if I am. I'll have to put on a pulse ox and check overnight.

The diffuser assembly is bigger than it looks - it's not just the diffuser material but a clear plastic piece that wraps halfway around the mask elbow. There are two flanges on the sides of the elbow you grip to pull the diffuser off:

Screen Shot 2018-08-11 at 9.46.38 PM.png (59.68 KiB) Viewed 20006 times

I used a pulse ox with my machine when I first started on it. It was handy because it helped show me in real time that although I felt suffocated by the pressure of the machine (which was actually not very high) my oxygen saturation was just fine while I was awake.

[palerider]

I see, thanks! So, how do I remove the diffuser?

That graph is very revealing. It's good to know -- maybe the hot air I breathe out warms up some of the air I breathe back in, making me think that I'm not getting enough oxygen, even if I am. I'll have to put on a pulse ox and check overnight.

You can always bump up the min pressure a cm or two, that will increase the vent rate considerably,

[nr224]

Thank you so much all, I will give it a try tonight.

Edit: turning it up to 7.0 and removing the diffuser and enabling level 3 EPR helped a lot. I think I'll be able to sleep now. You guys are wonderful, thanks a lot!

[zonker]

Thank you so much all, I will give it a try tonight.

Edit: turning it up to 7.0 and removing the diffuser and enabling level 3 EPR helped a lot. I think I'll be able to sleep now. You guys are wonderful, thanks a lot!

ALWAYS good to read something like that!

please come back and let us know how it goes.

[nr224]

Update! I've been on PAP therapy for a little while now. Still getting used to it. You guys are amazing how well you all adjust, reading on here. For me, I just couldn't stand the hose coming out of my face so I bought the Phillips Dreamwear. Someone online said they were using it with their Resmed device, which was surprising, but I didn't care -- I bought one anyway, because I just can't sleep with that hose.

Well, I got the mask now, but... it doesn't connect to my heated hose thing. So, is there anything special I have to do to get it to connect? I tried removing the little white plastic piece, tried connecting it to a smaller hose the Brevida mask came with, etc... no luck. Before I duck tape it together, any advice?

[nr224]

I just taped it together lol, given that both had the same diameter. Tomorrow I can 3D-print a fitting for the two to sit firmly in.

Either way the dreamwear is 10x better than what I had before