(04-15-2014, 01:50 PM)critterdoc Wrote: The Simplus mask does not provide a Diffuser System and the volume of expired air from the Simplus appears to be enormous compared to the Pilairo Q with the diffuser system fully invoked. With the fabric filter and the diffuser cover installed, expiratory venting seems to be palpably reduced to a relative trickle.
The venting is not really reduced to a trickle; rather the venting is no longer concented in one stream of air---the air is now venting in multiple directions instead of one main direction. The exhaust flow is effectively scattered
and the scattering makes is less noticeable than the concentrated jet flow of an exhaust vent found in the Swift FX for example.
Quote:but that leads me to another perplexing reference that I note with some frequency here - the dreaded mask leak. I have no way of assessing or comparing venting and mask leakage other than the "large leak" record that my machine offers. I have no clue how the machine derives that number, it's practical meaning, or how it differs from purposeful but variable venting that is built into various masks.
You are using a PR System One according to your signature. The LCD information on leaks is virtually useless: All the LCD tells you is how much time you spent in "Large Leak territory"
as a percentage of the night. It is quite possible to have some real leak issues that simply don't register as Large Leaks for a long enough period of time for the LCD to show anything other than 0.0%
To really understand the leaks on the System One, you need to look at the data in Sleepy Head or in Encore. And you need to look at the leak graph
as opposed to just the numbers.
The System One simply records total leak
: How much air is being leaked out of the system each minute? Loosely thinking that's the same as "How much air has to be added to the system each minute in order to maintain the desired pressure level?"
Total leak includes both the intentional leaks built into the mask to prevent rebreathing of CO2 AND all other (unintentional) leaks regardless of where they come from.
This is why the total leak data on a PR machine is NEVER, EVER going to be 0.0 L/min----there's always the intentional leak present.
To figure out how to interpret the leak numbers requires you to look in the owner's manual of your MASK. There will be a chart or a graph somewhere that lists or shows the intentional leak rate for your mask at various pressures. Once you know the intentional
leak rate, you can compare the total leak rate to the intentional
leak rate. If they're roughly the same (say within about +/- 5 L/min of each other) then you know that you don't have much unintentional leaking going on.
As for the dreaded official "Large Leak" on the PR System One. PR has not published exactly what constitutes an official Large Leak, although Encore will flag them and the screen's LCD will tell you how much time you're spending in Large Leak territory. By looking at a lot of data posted here and on other forums, it appears that the "Large Leak" line is somewhat dependent on the pressure you're using and also depends on whether you're using a Series 60 System One or a Series 50 System One. On the Series 60 machines at medium pressures (say 8-15cm), the Large Leak line seems to be about 70 L/min or so. That's roughly 20-30 L/min above the intentional leak rate for most masks being used in that pressure range.
As a general rule, the machine won't have any real problems compensating for an unintentional leak rate that is in the 10-15 L/min range and it should do an OK job for compensating for unintentional leaks in the 15-25 L/min range. So as a rule of thumb you want your total leaks
to stay below Intentional Leak Rate + 20 L/min
if possible if the leaks are NOT waking you up.
But if the leaks are waking you up, it doesn't really matter how big or small they are: Anything that wakes you up is worth trying to fix.
Quote:At this early stage of the game, I'd have to err on the side of tending toward venting and control of respiratory effort as being a ruling factor. Balancing that with maintaining increased pressure in the upper airway seems to be the trick but restriction of one's ability to blow off CO2 is of great concern to me. In that context, and in my view as a rank beginner with little noise sensitivity, the more aggressively vented Simplus FFM seems superior to the Pilairo Q Nasal Pillows for anyone other the most airway impaired.
Makes sense since you are NOT particularly sensitive to either the noise or airflow generated by the exhaust vents
But as someone who is on the opposite end of the sensitivity spectrum, all I can say is that I wish there HAD been some nasal pillows masks with diffusers when I started back in 2010. The exhaust venting from the Swift FX was a huge issue for me; it bounced off the covers and back into my eyes or my mouth drying them out. Or it flowed directly onto my chest and arms making me shiver all night long. Which problem I had to deal with depended on which way I had the elbow on the small hose pointed. But I could never find a direction where that exhaust flow was NOT noisy and windy. And I had to go through great lengths to protect my eyes, my lips and mouth, my chest, and my arms from the damn mask's exhaust vents each night.
I eventually started using a homemade diffuser cut from an air filter for a lawn mower. The leak rates with and without my homemade diffuser were essentially the same so I decided that I was not putting myself at serious risk of rebreathing, and diffusing the jet stream exhaust flow allowed me to (finally) get to sleep without arming myself with a handkerchief to protect the eyes, another hanky to protect the mouth, and two layers of long sleeves to protect my chest and arms from where ever that jet stream of exhaust was reflected to.
Quote:And lastly, yes I think I do qualify as a mouth breather especially when I am snoring and sleeping on my back - or at least so claims Blondie! It's a strange feeling when I relax my lips or even slightly open them and a blast of high pressure air is emitted. I'm not sure why but that problem seems more intense with the Pilairo than it was with the Swift Fx - perhaps because of reduced venting capacity. I am not aware of that problem when I am wearing the Simplus FFM.
You're not aware of the problem in the FFM because opening the lips does NOT cause a leak in the semi-closed pressurized system: Your lips are under the pressurized mask.
As to why it was more noticeable on the Pilairo than the Swift FX, that may have had more to do with the fact that the Pilario's cushion is larger and hence it's an easier target for the high pressure stream of air coming out of the open lips to hit. And once the air hits that cushion it bounces right back in your face so you've got two sources of irritation to notice rather than one.