Put my mind to rest about the Headrest--Please!

[feeling_better]

This is a rather old thread, and I being relatively new, just happened to stumble on it now By now, socknitster might already have her baby ??

I have been thinking about this issue on and off for the last 4 weeks. I have used the headrest about half the time. While oxygen sat tests are good way of finding it for a particular person, there may still be differences between masks for their CO2 wash out efficiency. Even though I had close to moderate/severe apnea, during the initial non titration study my O2 sat never went below 94% or so, so that by itself is not good enough. One wants to get the best possible given all of one's own non-changeable circumstances, IMO.

Here is my analysis (I have a scientific background, but not in CPAP machines. I have designed and got FDA approval for medical instruments.)

The wash out of the breathed out CO2 happens because of the constant pressure, and the constant flow through the out port, as people have pointed out. However much of these gets washed out depends on a lot of factors.

1. If your pressure is high, more of CO2 gets washed out.

2. If you breath out slowly more of CO2 gets pushed out.

3. The more the inherent built in leak through the out port for a given pressure, more of the CO2 gets pushed out. You can check the leak rate for a particular mask from its spec sheets, usually. The Headrest spec is 15LPM at 4cmH2O and 21LPM at 8cmH2O.

4. Now how far away the outport is from the nose tip, and the volume of air in the tube from the nose to the outport is the trapped a CO2 volume, only part of it will get pushed out. Some manufacturers may list this in the spec as the 'Seal Dead Space', which for the Headrest is 35cc --- I have a guess this may be higher for the Headrest than others.

Now here are some factors which may not be that obvious.

5. When you breath out, the qty you breath out does not simply go out immediately through the out port. The air in the tube leading to the machine will momentarily compress and some of the out breath will go into that tube, and get mixed in with the incoming air, the concentration of the CO2 near the face will be higher, decreasing as you go towards the machine.

6. The longer the tube, there is more take up of this used air into the tube!

7. If you have Cflex or Aflex, the pressure and hence the outport flow, as well as the resistance for the used air to enter the long tube, is DECREASED while breathing out. So Cflex and Aflex will decrease the CO2 push out compared to fixed pressure, for the same pressure setting.

Now you can do this simple experiment to get a feel of how long it takes to push out your breath thru the outport. Wearing the mask or nasal pillow, disconnect it from the main hose (so you have a relative small tube remaining). Do a couple of regular breathing with the tube open. Now close the open end of the tube tightly with your palm, and see how long it takes to push out your inhaled air thru the normal outport. You would be surprised how longer this is compared to your normal breath out time. Remember the actual time needed to push out all of your CO2 is going to be even longer than this, since the air that is pushed out is mixed with some good incoming air.

So what we need to know, CO2 wash out is rather complex to simply figure out. There need to be a specification for CO2 wash out efficiency, which is after some time of breathing, when steady state conditions are archived, what percentage of the CO2 is getting continuously removed. Your CO2 removal will be reduced by this percentage when you are using the cpap as opposed normal breathing. I have not seen any specification in my limited experience with any of couple of masks I have looked at.

Just becausue FDA approves something does not mean, they have this issue well covered. It depends on a lot of factors other than just the mask. Perhaps there is already a measure established. I would image this has already been done well for scuba diving gear, since the O2/CO2 levels are much more critical for that. If anybody has direct knowledge or experience kindly teach the rest of us.

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CPAPopedia Keywords Contained In This Post (Click For Definition): hose, nasal pillow, cflex, Titration, CPAP

[DreamStalker]

Actually, the issue of mask CO2 is more likely a function of:

1) the mask volume, and 2) the machine's pressure setting.

The higher the pressure, the easier to eliminate CO2 from the air circuit and the smaller the volume of the mask (relative to the location of the vent ports), the easier to eliminate CO2 from the air circuit.

The headrest has a very small volume (relative to nasal cushion and FF masks) and should perform just as well as most nasal pillow masks at eliminating CO2. The long thin tubes from the pillows leading up to the vent ports has small volume ... unfortunately, the long tube design also has a large surface area which is why the Headrest is prone to rainout issues more so than most other masks.

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CPAPopedia Keywords Contained In This Post (Click For Definition): nasal pillow, rainout

EDIT: Oh I see feeling_better has already covered this ... guess I should read all of the posts first

[Guest]

And I think Socknitster has switched to the Swift LT now, anyway.
B.

[packer]

I use the AURA most every night
I bought a recording oximeter also

results are great- in my opinion-[ not a doc yada yada ]

I think it simply is the volume of air moving through-
you cant get a very high concentration when it is constantly
circulating with the new air being blown in

I am very happy with aura- rain is only problem

just got a new swift lt today so will try that tonight- [ can get new mask through insurance couple times a year]

my guess is though it will still be aura

good luck with everything packer

[socknitster]

Yes I did have my baby, on the day you revived the thread, actually! I couldn't handle the thought of the headrest maybe not getting rid of all of the CO2 while I slept, plus I had rainout issues with it. I never used it more than a few nights. The swift II was my longtime friend and now I'm happily using the swift LT.

Charles "Charlie" Russell W_____

Born June 16, 2008 3:07 pm

8 lb, 9 oz

We are still struggling with jaundice brought on by the very rare ABO incompatibility. The baby also has reflux. And we have breastfeeding issues. Sleep doctors aren't the only incompetent doctors out there.

My baby got sick enough from the jaundice while doctors took a "wait and see" approach, that he couldn't breastfeed properly and I had to switch to bottles. Now he is relatively better and has the strength and energy to nurse directly, but since bottles are easier, he is refusing the breast about half the time. This means I spend most of my day trying to nurse my baby, hold him upright so he doesn't spit up all his food, then pumping my breasts to keep up the supply, then washing all the bottles and pump accessories. And try to keep my 4 year old happy in the few spare moments I have.

Hopefully things will get better here soon. Only gentle determination will prevail if I don't go nuts first.

Jen

[Flower51]

First of all, Hi Rested! LTNR. Do you have any pictures posted with how you've rigged up your a. headrest straps differently?
I need something that wouldn't press against the lymph nodes behind my ears and would not rest on my cheeks because of rosacea.

Second, is it an appropriate mask for using w/an autopap? As I am recovering from a lung mass I want to bring in the good air and get rid of the bad efficiently. Presently using a swift II which does rest on cheeks. Thanks, Terry

[rested gal]

Hiya Terry!

Hope your recovery is going smoothly!

I don't know if the way I route my homemade straps would suit you if you don't want anything touching your cheeks at all. But anyway, here it is -- a picture of me in my modified Headrest mask. The pillow is a PAPillow. If you didn't mind your eyes being covered, you could set the entire lower strap (the black one in this picture) up higher, to keep it off your cheeks. It works as well going across above the nasal pillows as it does cradling them from below.



Only thing missing is that if I were really getting ready for sleep, I'd tape my mouth and use a chin strap. Yeah, it takes all that to keep me from mouthbreathing during the night. You'd think after this long.... but no... still gotta use tape.

[Flower51]

Rested you are so kind to post your picture w/hose....lovely and helpful as always sis, Terry

[dvejr]

Just a minor addition to the thread.
I like the Headrest, and have been using one for several years now. Previously used a Swift. I share a bed with my wife, so the Headrest exhaust is best for her, too.
Never sensed any CO2 issues, but then again I probably wouldn't, would I?
No rainout issues to speak of. I've always draped my hose over the top of the headboard, or hang it from a hook when traveling. I usually run with water in the humidifier but no heat. (That seems to be sufficient humidification for me. My air in my house isn't terribly dry, so maybe that's why I don't need additional humidification from the CPAP, and then don't get water in the hose?)
When I travel I have a different CPAP, but use the same kind of headgear. I sometimes use a sweatband, like Rested Gal appears to in her photo, to hold the nasal interface from moving while I sleep. Most of the time I use a pair of pantyhose. Take the ankles and spread open. Roll the extra material in the middle round and round - makes a nice padding. Position that roll behind my head, cross the legs in front of my mask, and tie ends together behind my head.
Happy Sleeping!

[Flower51]

Hi Dvjr! What prompted you to make the switch from the Swift? Thanks! Terry And hello Rested if you are out there...how've you been?

[dvejr]

It was favorable comments here, from other users. Though one person's A+ is another person's C-, I felt like giving it a try.
My insurance helps to pay for a new interface every 6 months, but most of the ones I've used last a year or more. So, for me, I can experiment, and if I don't like one I can set it aside and keep using "the old one" for another 6 months.
Doug

[roster]

Wow. Very distracting.