[Equipment] Successful equipment modification

[tcurran]

    On my ResMed N20 I've been annoyed with the air being vented through the nasal cushion. It was noisy,  it dried my eyes out and it interfered with my sleep  positions especially on my stomach.

I found a DIY solution. I inserted a 3/4" tee (copper or plastic) between the two hoses. I connected a spare upper hose to the third branch of the tee. I sealed the other end of the hose with flexible medical tape (I used Hypafix.) but left the vent holes uncovered. I then used tape to seal the vent holes on the original upper hose where it attached to the nasal cushion. Please see the attached photo.

Now, there's no longer ANY air being discharged near my face. The air now gets discharged through the secondary hose. No more dry eyes, no more noise, and I can sleep in any position, even burying my face in my pillow. (My index is under 2.) You would not believe how comfortable it is.

I am curious however if this modification affects oxygen flow.  I am a mechanical engineer and believe that with the tubing diameter, length and flow rate the oxygen and carbon dioxide diffusion should not be affected. I slept with an oxygen pulse oximeter and never went below 98%. I would love to hear your comments on this, especially if you are a professional.

[DenMan]

That's really cool but isn't the purpose of the vent holes at the mask to flush out CO2?

With your solution CO2 would need to find it's way back through the tube against incoming flow, or not? I guess it does so to a certain degree but is it enough to prevent built up CO2 above a dangerous level, especially with higher pressure?

Excuse my newbie questions but this is really interesting!

Edit: Ok second thought, this is even cooler ? I would absolutely try it if it's safe.

[Sleeprider]

You created a fairly significant dead space between the T and mask. Congrats, you just kludged a new variation of enhanced expiratory rebreathing space (EERS) https://www.apneaboard.com/wiki/index.ph...ace_(EERS)

[Rich66]

Another variation with good results is using the hose connector piece from a F30i mask between the heated hose and the N20 hose. It moves the exhaust port right up by the heated hose. And then block off the exhaust holes by the mask. I found the results so good that I quit taping my mouth shut, after two years of taping my mouth. It really helped.

[Nightynite]

Some of these mask exhausts ports are so small it’s hard for me to believe that they actually work.
Especially during the short exhale time vs the positive air pressure in the same area.

[tcurran]

As I stated it's my engineering "judgement" that the size of the tube, flow rate and pressure would allow for enough diffusion and mixing to prevent this.  That is why, as a simple test, I used the oxygen pulse oximeter to assure that I was getting enough oxygen. It surely would be nice if I could get a proper sleep study done using this.

[Gideon]

It is, simply put, CO2, specifically the need to remove CO2 and other respiration byproducts that provide our drive to breathe. EERS systems are designed to increase our CO2 levels slightly. This type of system will prevent some types of central apneas and prevent O2 Dips from that cause,

[Old Steve]

I made a EERS with about a 6-8 inch length tube, I used it for two nights and that was enough for me.  I felt like I was slowly suffocating.  

[Sleeprider]

tcurran, I was not criticizing your design and implementation. I meant to point out we intentionally increase dead-air space for individuals that need a little more CO2 to stabilize respiration. Read the EERS wiki and you will see a number of members have experimented with this. Since you used good engineering judgement to endure a good design, you will find the EERS lets you calculate the rebreathing space.