Mask leakage - should I be concerned

[Pugsy]

ResMed starts falling over when excess leak goes past 35 L/min..not total leak. ResMed never gives us a total leak number to go by,
Respironics machines won't start falling over until excess leak goes past 100 or total leak up around 120 whichever someone wants to go by.
I may have missed it where PR said Respironics couldn't handle excess leak as well as ResMed.
What I understood him to say was that we can't judge Respironics data using ResMed values.

Why ResMed came up with the 24 L/min thing...beats the hell out of me but it has been that way ever since I started therapy.
I think it is an ultra conservative line in the sand.
From my own personal experience...up to 30 L/min excess it seems to work fine...between 30 and 35 things got a bit iffy and I started seeing some unknown flags and over 35 I got a big blank space where just right before it I was getting an unknown...now is the blank space because the events quit happening or the machine was clueless???? Dunno and have no way to know for sure but I always assume the worst in this case just to err on the side of caution.

Here's a thread with one example...I have a better example that shows more 30ish leak numbers somewhere but can't lay my hands on it at the moment and I am short on time.
viewtopic.php?f=1&t=76445&p=698087&hili ... ne#p698087

Bottom line...ResMed and Respironics report and do things differently and trying to use the ResMed threshold for Respironics data could maybe alarm people when there is no need for alarm. It's not accurate and it can be alarming so why use it?
Now if someone wants an ultra conservative line the sand..hey...use it. Hurts nothing but if someone is getting large leak messages and contemplating changing something when the large leak message is an error...that's not good. It causes unneeded stress when there's no need for that stress. This therapy is difficult enough without having people trying to fix a problem that doesn't exist.

[Pugsy]

the simple calculation trumps it, if you have knowledge of the actual mask curve, and SH does.

Ah...but you are assuming something not in evidence...that SH knows the curve and has it right and Marks way of calculating was correct.

We are trying to tell you that Mark came up with a lot of good ideas but didn't finish a lot of them and some work half assed and this is Beta software...it has a lot of his ideas left unpolished and working half assed.

The basic stuff...yeah...easily vetted by using the appropriate brand software but some of this other stuff...no way to verify. Maybe he got it right and maybe he didn't. And PR and I both worked with Mark over several SH versions...Respironics way of doing things gave him some big headaches when it came to coming up with any sort of baseline especially when it came to leak data.

[linuxman]

the simple calculation trumps it, if you have knowledge of the actual mask curve, and SH does.

Ah...but you are assuming something not in evidence...that SH knows the curve and has it right and Marks way of calculating was correct.

We are trying to tell you that Mark came up with a lot of good ideas but didn't finish a lot of them and some work half assed and this is Beta software...it has a lot of his ideas left unpolished and working half assed.

The basic stuff...yeah...easily vetted by using the appropriate brand software but some of this other stuff...no way to verify. Maybe he got it right and maybe he didn't. And PR and I both worked with Mark over several SH versions...Respironics way of doing things gave him some big headaches when it came to coming up with any sort of baseline especially when it came to leak data.

The curve is supplied by the preference setting, in the form of two end points used for a linear approximation of the curve. The software just has to know how to work out y=mx+b. There's nothing difficult about that. If he didn't get that right, then there are probably other problems....

[linuxman]

ResMed starts falling over when excess leak goes past 35 L/min..not total leak. ResMed never gives us a total leak number to go by,
Respironics machines won't start falling over until excess leak goes past 100 or total leak up around 120 whichever someone wants to go by.
I may have missed it where PR said Respironics couldn't handle excess leak as well as ResMed.
What I understood him to say was that we can't judge Respironics data using ResMed values.

He said that Resmed could hold pressure better at higher flow rates, but didn't actually speak to how that might effect detection, and I'm sorry about conflating those two things. So if the issue is that Resmed actually falls over on detection at lower excess pressures (24-35L/min or so - regardless of the total flow) and Respironics can stay sane to 80-90 or more, than I understand why you'd set a lower warning threshold. I thought you were doing so just because of it reporting total leaks. That's a big difference in performance. Does Resmed gain some sort of accuracy advantage that's a worthwhile trade-off vs ability to continue correct detection at higher leaks? I know leaks aren't everything, and generally get under control, but I'd think they'd want to strive to keep pressure up and have detection as leak tolerant as possible. I guess I'm glad I have a Respironics machine...in case I ever have bad leaks.

[palerider]

So, you're saying that 24L/min of excess leak as a redline threshold is appropriate for Resmed, but not for Respironics? Sure, if the Respironics machine is just so much better at handling excess that 60L/min is ok..then sure, but I see no evidence of that. Why wouldn't the amount of total flow they can tolerate be at least in the same ballpark? Total flow for the same mask with 24L/min of excess for both machines would be identical (75-ish for mask with native leak at 50L/min).

because they are not the same machine, they don't use the same technology, they don't have the same hardware, and they don't have the same programming.

resmed can 'tolerate' a whale of a lot more leak without compromising therapy pressure, download a resmed clinical manual and look at the chart in the back that shows how much leak they can handle and still maintain pressure. then pick your jaw up off the floor.

the 24lpm on RESMED is a comfortable, safe level where the machine can still accurately differentiate between central and obstructive apnea. though in practice, it will still do that up into the mid 30s of leak, after that the machine starts flagging unknown apneas because it can't reliably tell the difference.

since your machine uses a near totally different method to differentiate, ASSuming that the parameters of operation are the same is.... welll, you supply a word.

this is more complicated than you understand.

Ok, great... I'll take your word that Respironics machines suck at maintaining pressure at higher flow rates, and start to drop off pressure at point that's some amount lower than Resmed. If that's the case, why would one increase the redline threshold when using the Respironics? Apparently it can't handle as much excess, so you should lower the redline to warn you at a lower excess pressure.

Or, you could READ what I said, which is that the machines are DIFFERENT and blindly applying the parameters from one to the other makes no sense!

I have *no idea* what the practical limits of the respironics machine are, because they don't publish the specs like resmed does.

I mean this in the nicest way possible.... get a clue.

[palerider]

I may have missed it where PR said Respironics couldn't handle excess leak as well as ResMed.

That's because he never said, or implied that.

.

[palerider]

the simple calculation trumps it, if you have knowledge of the actual mask curve, and SH does.

Ah...but you are assuming something not in evidence...that SH knows the curve and has it right and Marks way of calculating was correct..

The more important thing he's assuming is that the resmed 24lpm excess leak amount has anything to do with respironics machines, and of course, that is a baseless assumption.

Respironics excess leak tolerance may be more, or less than that, but we have no way to know, since they refuse to publish any specs!

What they do provide is a simple flag, as you know, Pugsy, that says... "Too much"

But, why listen to the machine when you can make up shit instead?

[palerider]

So if the issue is that Resmed actually falls over on detection at lower excess pressures (24-35L/min or so - regardless of the total flow) and Respironics can stay sane to 80-90 or more, .

Most people are able to comprehend the simple fact that resmed reports excess leak and respironics report total leak, why can't you?

Please stop trying to compare apples and oranges.

[linuxman]

So if the issue is that Resmed actually falls over on detection at lower excess pressures (24-35L/min or so - regardless of the total flow) and Respironics can stay sane to 80-90 or more, .

Most people are able to comprehend the simple fact that resmed reports excess leak and respironics report total leak, why can't you?

Please stop trying to compare apples and oranges.

Yes I'm aware of that - those are in the same units. I was using (approximately) Pugsy's numbers there where she thought things started falling over for excess leak, presumably from her actual observations.

"Respironics machines won't start falling over until excess leak goes past 100 or total leak up around 120 whichever someone wants to go by."

[palerider]

So if the issue is that Resmed actually falls over on detection at lower excess pressures (24-35L/min or so - regardless of the total flow) and Respironics can stay sane to 80-90 or more, .

Most people are able to comprehend the simple fact that resmed reports excess leak and respironics report total leak, why can't you?

Please stop trying to compare apples and oranges.

Yes I'm aware of that - those are in the same units. I was using (approximately) Pugsy's numbers there where she thought things started falling over for excess leak, presumably from her actual observations.

"Respironics machines won't start falling over until excess leak goes past 100 or total leak up around 120 whichever someone wants to go by."

She *OBVIOUSLY* meant, and has said hundreds of times, TOTAL leak, since that is all that respironics reports.

[Pugsy]

actually what she said she thought she covered both bases... whatever a Respironics user wants to use...total or excess numbers.

Respironics machines won't start falling over until excess leak goes past 100 or total leak up around 120 whichever someone wants to go by

And yes from past experience (both personal and looking at hundreds of other Respironics reports where large leaks were flagged and/or the leaks were so bad the machine was clueless) with Respironics machines AND Encore in which we could choose the leak reported...total or unintentional (excess only).

If someone just HAS to know exactly at what threshold Respironics flags a large leak...they have to use Encore and hope they catch a number where right below X number is not a large leak flag and above it there is a flag. And toggle the way the leaks are reported to catch the threshold.
I rarely ever got a large leak flag on my Respironics reports...but it's rare I don't get at least one short lived LL flag with my ResMed reports.
I can't believe that my leaks change that much between machines.
From my own personal experience with my Respironics APAPs....I never saw a large leak flag below 85 L/min total leak...but I did see LL flag at 90 sometimes but not all the time (probably related to the pressure I was using at the time) or above. That's the closest I could get to an actual line in the sand. I never had the opportunity to see total leaks at 86 or 87 or 88 or 89 to spot the exact line in the sand.
The pressure being used at the time of the large leak made a significant impact on if a LL was flagged or not because of the vent rate.

I have seen Respironics apaps/bipaps when in auto mode behaving like a fixed pressure machine....straight pressure line and the people thinking their machine was broken. Never saw it unless total leak was at 120 or thereabouts...at 120 L/min total leak is going to have a really big chunk of that number be excess leak...common sense will tell you that even at some really high pressures where the vent rate is on the high side... As long as total leak was below 100 L/min I never saw a Respironics machine get clueless and act weird.

Now I have seen large leak flags when total leak reported was around 80 L/min but in all those cases the people were using really low pressures (like 6 cm) which is going to have a really low vent rate anyway so total leak is expected to be lower. But the machine was still functioning normally i.e...not totally clueless.

When I tell someone to change the threshold in SH to something around 60 to 70 L/min...it's a conservative number for most people to be using. It's not on the high side. In actuality the threshold for LL territory is going to be much higher but setting a conservative number gives a bit of a cushion for those few people who might be using a really low pressure and have a relatively low vent rate. It's the best we can do since we aren't ever given any sort of line in the sand from Respironics...which is really hard to do anyway when variable pressures are used and the machine doesn't/can't know what type of mask is being used.
I figure if they feel better seeing that little % of time over red line statistic then it hurts nothing to let them see it but I sure don't want it to be scaring someone when they don't need to be scared.

F & P machines have a different threshold...it's 60 L/min total leak.

DeVilbiss has a more generous threshold up around Respironics at 90 to 100 L/min total leak.

ResMed is the oddball here in its reporting of excess only leak numbers and their line in the sand simply isn't the same line in the sand number with the other machines. Everyone else reports total leak and total leak varies when auto adjusting pressures are used so the line in the sand moves around all the time. We can't put a static line in the sand and expect it to be 100 % correct when pressures vary and especially a static line in the sand for a brand of machine that we aren't using. That may be part of the reason Respironics has elected to not publish a line in the sand.

Now most people won't have a problem using that rather low (compared to what their line in the sand really is) line in the sand from the default ResMed number because their excess leaks don't exceed 24 L/min anyway...so it hurts nothing to use the ultra low line in the sand.
The problem is when SH uses that number and scares the hell out of someone telling them they are having major leak issues and they aren't having even one leak issue. If the dummy light doesn't flag a large leak...it didn't happen...at least according to the machine and we have to trust the machine ultimately as having the final say so.

When SH tells me I spent 20 % of the night over the threshold (using the 24 threshold) when I use my Respironics machine and I look over at the Events graph and don't see one large leak flagged....It's pretty obvious that SH is wrong. Now I know what the deal is but some people don't understand it and they get all worked up and think they need to change masks or use a chin strap or whatever and start doing things trying to fix a problem that doesn't exist...and that's why I point out that the line in the sand is the wrong line for their machine.
This therapy is hard enough in fixing real problems and there is simply no sense in adding stress causing people to go try to fix a problem that doesn't even exist.

[palerider]

The other thing to remember is that the ll total leak level probably​ varies with pressure... But, that's another respironics secret.

[Pugsy]

The other thing to remember is that the ll total leak level probably​ varies with pressure... But, that's another respironics secret.

Yep. That's why I don't get all gung ho about figuring out exactly where large leak territory begins. Too many variables in calculations that we aren't privy to.
I trust the machine or I wouldn't be using it. If it isn't squawking about large leaks on the Events graph then I am not going to worry about large leaks.

I know that some sort of vent rate is used somewhere because Encore will report unintentional leaks if you want to set it to report leaks that way... so for it to be able to do that there must be some sort of calculations going on with total leak and vent rate and pressure...we just don't know what they do or how they do it.
Since there is no mask selection available the vent rate used is probably a generic vent rate at whatever pressure is used...so there's a plus or minus variation right there to start with.
Is any of this 100 % spot on accurate...nope too many variables that we don't know but it gets us close enough I suppose.

Me...I am good with looking at the dummy light on the Events graph and if it isn't lit up then I don't see any sense in looking at the leak any further anyway. At least as long as the leaks aren't waking me up and if they are that's a whole different situation.

[palerider]

The other thing to remember is that the ll total leak level probably​ varies with pressure... But, that's another respironics secret.

I know that some sort of vent rate is used somewhere because Encore will report unintentional leaks if you want to set it to report leaks that way... so for it to be able to do that there must be some sort of calculations going on with total leak and vent rate and pressure...we just don't know what they do or how they do it.
Since there is no mask selection available the vent rate used is probably a generic vent rate at whatever pressure is used...so there's a plus or minus variation right there to start with.
Is any of this 100 % spot on accurate...nope too many variables that we don't know but it gets us close enough I suppose.

well, according to mark, there's no excess leak data recorded on the card, (unless he's been missing it all these years) so encore must be doing some kinda math to guess it, likely what you suggest...

Me...I am good with looking at the dummy light on the Events graph and if it isn't lit up then I don't see any sense in looking at the leak any further anyway. At least as long as the leaks aren't waking me up and if they are that's a whole different situation.

well, that's because you're wise and experienced

[Pugsy]

well, according to mark, there's no excess leak data recorded on the card, (unless he's been missing it all these years) so encore must be doing some kinda math to guess it, likely what you suggest..

Something somewhere in Respironics ..either the machine or the software is doing some sort of excess calculations.

My apologies are if these are huge...Photobucket archives and I can't change thumbnail size...or at least I never figured out how.

Same night...top full report excess/unintentional leak only and bottom snippet is total leak.