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leak rate [questions]
#1
leak rate [questions]
I have a list of dumb questions.  basic stuff I think I should know but if I ever did know I've forgotten.  here's a few on the subject of leaks.

no matter that the mask test tells me my mask is sealing well, resmed & SH tell me I always have baseline leak of at least about 4 L/m.  historically I've ignored it because it's a low number and not close to the redline.  lately that baseline has been higher: last night for example weighted avg of 13+.  still below redline but it has prompted my curiosity.  

is what I'm calling a baseline leak normal? is everything under the redline normal? 

does leak rate rise and fall with pressure? again, for all these questions I'm assuming no unintentional leaks, by which I mean leaks not somehow accounted for by design.

when I watch the real time leak bar graph on the asv display, it seems that measured leaks are higher on inhale than exhale.  why is that?  it seems counter intuitive to me.

assuming the mask test is reasonably accurate, it would seem this baseline leak is expected and by design?  

when leak rate is at it's lowest (and not zero because it never is zero) and appears to be fairly consistent for long periods - what I'm calling baseline, with no unintentional leaks - is that the amount that flows nearly all the time from the mask's exhaust port / diffuser?

I know there are differences between how mfgrs report leaks.  I'm asking about my resmed asv and p10 nasal pillow mask but replies explaining the differences between mfgrs re leak reporting are invited as it will help others too.
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#2
RE: leak rate
ASV machine, because of the way they work by pushing Pressure higher than you would otherwise have it as they provide that push of higher PS to initiate a breath when your body said not too.

Think about the physics, the higher the pressure the higher the "Intended" leak has to be and as such the higher the "baseline" leak will be.
Does this hold up?  Yes per some work I just did with PR masks and am preparing for the OSCAR Wiki, (I'll bet you didn't look there)
Look at the following chart of Mask Flow rates vs Pressure.

          
The numbers come from https://www.continuedcare.com/wp-content...-ports.pdf
Fred Bonjour - Project Manager and Lead Tester for OSCAR - Open Source CPAP Analysis Reporter 
OSCAR

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#3
RE: leak rate
thanks. and you're right. I know I can search for answers but I did not look to wiki. sometimes searching can take a while or lead people like me down too many rabbit holes (too easily distracted). sometimes it's more efficient to ask and not too hard for a knowledgeable someone to at least post a link. plus your answers will no doubt help others besides me.

so, is it fair to conclude that the baseline leak I'm talking about is normal and by design, it is the constant flow of air that I feel flowing outward from the exhaust port / diffuser, it rises with increased pressure and it's nothing to concern ourselves about as long as it's below the redline? and it's odd that the leak rate increases on inhale?
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#4
RE: leak rate
rereading your reply, I now realize you answered my question about higher leak on inhale and that's because ipap is higher than epap or inhale pressure is epap plus pressure support so ipap will almost always be higher than epap. here's me slapping forehead. of course! thanks again for responding to my questions!
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#5
RE: leak rate
(04-21-2019, 05:52 PM)sheepless Wrote: thanks. and you're right.  I know I can search for answers but I did not look to wiki.  sometimes searching can take a while or lead people like me down too many rabbit holes (too easily distracted).  sometimes it's more efficient to ask and not too hard for a knowledgeable someone to at least post a link.  plus your answers will no doubt help others besides me.  

so, is it fair to conclude that the baseline leak I'm talking about is normal and by design, it is the constant flow of air that I feel flowing outward from the exhaust port / diffuser, it rises with increased pressure and it's nothing to concern ourselves about as long as it's below the redline?  and it's odd that the leak rate increases on inhale?

On the Resmed as long as your below the Red Line and the leaks are not dsturbing your sleep then everything is good as the leak is too small to effect the efficiency of your machine or your treatment
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