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[Equipment] Rebreathing causing Hypercapnia (CO2 – Carbon Dioxide Poisoning)
#21
RE: Rebreathing causing Hypercapnia (CO2 – Carbon Dioxide Poisoning)
It looks good.  
I would up the minimum pressure to 8, and change the EPR to 2.
The higher min pressure will help you breath easier, and with EPR at 2, EPAP will only drop to 6.

You had a leak "spike" around 3:30.  Nothing to worry about unless that was going on all night.
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INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE.  ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA.  INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.
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#22
RE: Rebreathing causing Hypercapnia (CO2 – Carbon Dioxide Poisoning)
if you would suffer Hypercapnia you would start to hyperventilate ... your respiratory rate hovers around 13 - which is like 10 miles away from that.

But you can always do the math - measure the time from the start of the exhalation to the beginning of the inhalation. (with your resp. rate I assume something a little over 2 seconds)
in that time your tidal volume needs to be nearly completely vented.

580 ml in 2 seconds = 17,4 Liters per Minute.
check that against the intentional leak from your mask at the given pressure ... if the vent rate is above that you are in the safe-zone.

and be assured: there is no such thing as negative flow back in the machine. You might be "strong" enough while awake (or at least believe that you can breath forcefully enough to do that - but I doubt anyone is stronger than the turbines in the machines) but not during sleep - you would simply open your mouth to exhale. (and you would do the very same thing before starting to hyperventilate through your nose - except you did some crazy stuff to not be able to open your mouth)
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#23
RE: Rebreathing causing Hypercapnia (CO2 – Carbon Dioxide Poisoning)
I can only say that all-at-once I could no longer breathe with the P10 in the middle of the night and that was after using it over a year. I was never sure if the pillow was blocking the exit air or what, but I would wake in the middle of the night gasping for air, but only if I was sleeping on my side. I found it harder to breathe through even a brand new mask/cushion. I've just put it down to me - I'd put on 10 pounds about the time I started having problems.

I've shelved my P10 for the moment and primarily alternate between the Dreamwear and the Swift FX pillows (which I used before the P10) and have no problems.
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#24
RE: Rebreathing causing Hypercapnia (CO2 – Carbon Dioxide Poisoning)
(07-03-2017, 07:41 AM)HULK Wrote: Perhaps I should try a different mask for the next week of the trial? (starting this Thursday 6th July 2017)

It's possible a new (different model or style) mask will help.  As others have said, the mask leaks though the exhaust port by design.  If it isn't, then something's wrong.

When i got started, I tried 3 different masks until I found one that worked for me.
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#25
RE: Rebreathing causing Hypercapnia (CO2 – Carbon Dioxide Poisoning)
(07-03-2017, 07:59 AM)HULK Wrote: How does this look?

looks good to me for the first week.
I agree with min 8 for the OA/H and epr2, possibly 1 and see how the ca go.
you could tighten the max down to 14
I wouldn't worry over the ca, as they are small in number. There is nothing you can but reduce the epr, they should settle down within days to 3 months.

you adjust the pressure by going to the clinical menu
http://www.apneaboard.com/resmed-s9-cpap-setup
mask fit http://www.apneaboard.com/wiki/index.php...ask_Primer
For auto-cpap, from machine data or software. You can set the min pressure 1 or 2cm below 95%. Or clinicians commonly use the maximum or 95% pressure for fixed pressure CPAP, this can also be used for min pressure.
https://aasm.org/resources/practiceparam...rating.pdf
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#26
RE: Rebreathing causing Hypercapnia (CO2 – Carbon Dioxide Poisoning)
Having been a Rescue/recovery Diver for over 40yrs and used (both open and closed circuit) single stage, double stage, re-breather, and hardhat, as well as BA (fire Rescue, confined space).

Because of my training (mouth in/nose out), I use a FFM.

You are overthinking any issue, just relax and breath...

... Philip
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#27
RE: Rebreathing causing Hypercapnia (CO2 – Carbon Dioxide Poisoning)
Hi All, first time poster long time CPAPer.

HULK I found exactly the same issue with my new P10 and I believe you are totally correct about rebreathing CO2 concerns. 

It took a few nights to figure out what was going on.  By the last night of use I was a mess, woke up several times breathing fast and heavy like I was running up hill.  Mouth breathed for a while, things normalised and I would go back to sleep.  Felt progressively more drugged during the day and my head was swimmy.  Changed back to my old FX mask and things are improving.

I really like the comfort aspect of the mask so have been trying to figure out whats going on, searching online etc and your CO2 info really struck a chord.  Oldly yours is only the second post I have found anywhere online where someone talks about concerns that the P10 is not venting enough.

I have contacted the retailer and Resmed about it mostly to ask if it could be a manufacturing fault because the vast majority of comment online is all good.  Resmed say 'no such probelm exists, never had a manufacturing fault, you need to get used to it or change masks'.  The retailer had heard of the issue and said some people believed that it was due to washing the mesh in hot water causing it to close up.  I washed mine in cold water.  I have a microscope and took a close look at the mesh and it all looks pretty normal, nothing crushed or blocked - not that I have anything to compare it to- see attached images if you care to.  This is about 300X mag.

As you point out its easy enough to prove.  With the mask on as normal I just detached the tube and blocked it.  Then tried to breathe, fast or slow, hard or easy it doesnt matter, I can't.  I just can't get anywhere near enough airflow through the mesh vent.   Theres no where else for spent air to get out.  If the majority of my second hand breathe is not being expelled before i breathe in it must be going somewhere, back up the tube, mixing with new air and then being rebreathed.  Not enough new air though.  Hence my laboured breathing experience, I was running low on oxygen and as you point out getting more CO2 than is healthy.  I have a Swift FX that I have gone back to and an F&P Pillario.  Doing the same test on both of these you can breathe way better, almost normally.  So there is a vast difference between the exhaust flow rate of these devices and the P10.  Question is do I have a bad one?  Shouldn't there be a similar flow rate across all devices?  That would seem to be the logical answer to me.  I'd love to know if everyone else has the same test experience.

What I do know is a lot of people reviewing the product are thrilled with the fact that there is very little sound and air flow out of the vent... sounds just like mine so mine is likely operating normally.  

The P10 is a lot more comfortable and stable than the FX so Im thinking of enlarging some holes.   I was going to try a hot pin and hopefully make small holes that dont whistle.  

All the best


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#28
RE: Rebreathing causing Hypercapnia (CO2 – Carbon Dioxide Poisoning)
I totally disagree with the conclusions and recommendations regarding the P10 above. The reason you feel more air venting when you are inhaling is that the machine pressure is higher during IPAP than EPAP. The machine's airflow volume is about 3-5 times the amount required for your respiration, and while the mask is quiet,there is a lot more venting than you think occurring. I have never had a problem with a P10 mask but the ones who do, are washing the frame or have a situation where the venting membrane gets very wet. Avoid that, and you won't have an issue. If you feel a need to modify the venting on a mask, I suggest you just change to another model that vents conventionally rather then attempt to alter the mask vent with home-made holes.
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INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.
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#29
RE: Rebreathing causing Hypercapnia (CO2 – Carbon Dioxide Poisoning)
I see nothing wrong with opening up the vents on the P10. i do not see a problem until one opens the vent so much that the machine can't keep up. Just my thoughts.

Some people may be more sensitive to CO2 build-up than others.

The P10 does not work for everyone.

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#30
RE: Rebreathing causing Hypercapnia (CO2 – Carbon Dioxide Poisoning)
I disagree with modifying any part of the air delivery system, including the mask. The mask is engineered to deliver air and vent a certain amount of air to prevent CO2 rebreathing
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