Is a leak rate of 30 or more considered problematic?

[DeeCPAP]

Is a leak rate of 30 or more considered problematic? I just went over some old dates on my SleepHead software. At that time, I didn't look at much except for the AHI, but now that I know the leak rate is very important, I was wondering what levels (consistent or not) are considered bad if it's for any extended period of time, not just a few minutes or so. Putting it another way, what's the maximum leak and how long does does the leak have to be before you know something's wrong.

Thanks

[Guest]

Is a leak rate of 30 or more considered problematic? I just went over some old dates on my SleepHead software. I didn't look at much except for the AHI, but
now that I know the leak rate is very important, I was wondering what levels (consistent or not) are considered bad. Putting it another way, what's the maximum leak before you know something's wrong.

Thanks

That all depends on which mask you are using and the pressure. Your mask should have come with a graph showing the leak rates and pressure on a curve.

[DeeCPAP]

Putting it another way, what's the maximum leak before you know something's wrong.

Thanks

That all depends on which mask you are using and the pressure. Your mask should have come with a graph showing the leak rates and pressure on a curve.

Thanks, that'll help for future reference, but I changed masks quite a few times in the last few (or more) years so I wouldn't know which masks I used.
Isn't there a general level or range that would apply to most masks rather than specific to a particular model of mask?

[Pugsy]

ResMed machines report only excess leak...so all of that 30 L/min is above the vent rate which is called intentional leak.
Mask vent rates at so and so pressure are only useful when total leak is reported. Your machine doesn't report total leak (total leaks is the mask vent rate plus excess leak).
Vent rates are not particularly useful when excess only leak is reported.

ResMed has decided to use 24 L/min excess leak as the red line for where they say the machine can start losing the ability to compensate for excess leak.
So above 24 L/min things start getting a bit iffy and the further you go the iffier it gets in terms of accuracy of sensing, recording and responding to apnea events.

From my own personal experience with a ResMed machine and large leaks...I found that between 24 and 30 the machine seemed to be still fairly accurate. Between 30 and 35 L/min excess leak I started to see some "unknown" apneas which meant the machine sensed something was going on but because of the leak it could quite decided on what it was. With leaks above 35 L/min I saw big blank spots where 20 minutes before when the leaks were at about 33 L/min I was seeing green "unknown" apnea flags...now I suppose maybe I wasn't having any events but I think that was probably extremely unlikely...I think the blank spot was because the machine lost the ability to sense and record what might be going on in the face of leaks past 35 L/min.. I think that particular night it went up to around 40 L/min.

[DeeCPAP]

ResMed machines report only excess leak...so all of that 30 L/min is above the vent rate which is called intentional leak.
Mask vent rates at so and so pressure are only useful when total leak is reported. Your machine doesn't report total leak (total leaks is the mask vent rate plus excess leak).
Vent rates are not particularly useful when excess only leak is reported.

ResMed has decided to use 24 L/min excess leak as the red line for where they say the machine can start losing the ability to compensate for excess leak.
So above 24 L/min things start getting a bit iffy and the further you go the iffier it gets in terms of accuracy of sensing, recording and responding to apnea events.

Thanks, Pugsy (again and again!) My doctor's tech said that when I wore nose headgear (rather than full face), I was opening my mouth. He said during REM sleep is where the leak rate was highest. With those leaks, it's the same as not wearing a mask at all. This makes sense. So, I've been rereading my SleepHead data from previous years, I saw many, many leaks of 30 or higher for long period of time, not just a blip here and there. They seem to correspond to the two REM 90 minute periods of REM sleep everyone has.

And there's a bottom line to this line of thinking, but I'd like to hear more first...

[Guest]

ResMed machines report only excess leak...so all of that 30 L/min is above the vent rate which is called intentional leak.
Mask vent rates at so and so pressure are only useful when total leak is reported. Your machine doesn't report total leak (total leaks is the mask vent rate plus excess leak).
Vent rates are not particularly useful when excess only leak is reported.

I'm gonna guess that is only helpful/useful if the cpap knows which mask is connected and it is the correct mask.

[svo]

....my leak rates are on the upper side of the scale sometimes...but I also noticed that my AHIs are always less than 3 for most parts (95% of the time)...the leak noise does not wake me up at all...while still sleeping.. my wife says that I adjust the mask and continue sleeping....it is my opinion that the most important thing is the AHI number, correct?...I sleep sideways and I am an "open mouth" breather and I have been using Amara View since I started and will change to any oyher..I am confortable and will not rock the boat...<S>...

[Pugsy]

it is my opinion that the most important thing is the AHI number, correct?...

Well....that sorta depends on how accurate the AHI might be.
If you have a 2.0 AHI and you spend 3/4 the night with 45 to 50 L/min excess leak (let's use Resmed's numbers) then that 2.0 AHI might not be so accurate.
Now 15 to 30 minutes of big leak like that...it's only going to maybe affect only the time in big leak which really doesn't impact the overall AHI over 7 or 8 hours all that much.
But 5 or 6 hours in really big leak...that could mess with the accuracy of that nice low AHI.
Problem with low AHI in the face of big leaks is we don't know for sure if nothing happened or they happened but the machine was clueless and when I don't know for sure I have to assume the worst.

It's why I always look at how long I spent in big leak if I happened to hit big leak. I have slept through some really big leaks so I know people can sleep through them.

What I evaluate when I look at a report....
AHI and leak at the same time...then if I see any large leak flags I look a little closer to see just how much time I might have spent in large leak.
That's all I look at.
If I don't see any large leak flags then I rarely bother looking at anything else.
I have to trust the AHI and to trust the AHI I need to make sure that large leak time frames aren't prolonged.

AHI that is nice and low.....meaningless if the bulk of the night was spent deep into large leak territory.

[DeeCPAP]

AHI that is nice and low.....meaningless if the bulk of the night was spent deep into large leak territory.

Can you take a quick look at this graph from maybe a week ago? (click it and it enlarges) The AHI is VERY low, but the leaks are VERY high. Amazing because it doesn't seem there's time to get REM sleep during the night! A full cycle of REM sleep is 90 minutes long! That's sleep deprivation and it was literally considered torture during WWII. https://imgur.com/gallery/aNc47h8

[RestlessinWoolley]

My machine in monitor mode usually shows between a 32-34 leak with 100% mask fit. My Quattro FX anyway. My simplus when I can get it to seal is over 40. I am unable to view my graphs on Sleepyhead so I cannot tell if it spikes any but my mask alarm set on 15 seconds of large leak has yet to go off.

[Pugsy]

Can you take a quick look at this graph from maybe a week ago? (click it and it enlarges)

Where's it at...I don't see a link?

You might read up on sleep stages
and look at the hypnograms to see what the normal cycles look like and how long they last.
90 minutes in REM is unusual in one chunk...now over the entire night maybe...only 20 % of the night is normally spent in REM and that is from several REM segments added together.

https://en.wikipedia.org/wiki/Sleep#Stages

see the image here
https://en.wikipedia.org/wiki/Hypnogram

[Pugsy]

My machine in monitor mode usually shows between a 32-34 leak with 100% mask fit. My Quattro FX anyway. My simplus when I can get it to seal is over 40. I am unable to view my graphs on Sleepyhead so I cannot tell if it spikes any but my mask alarm set on 15 seconds of large leak has yet to go off.

You are using a Respironics machine and it doesn't report leaks like the ResMed machine does.
Respironics reports total leak and total leak is composed of vent rate plus any excess leak.
Actually ResMed is the odd man out...pretty much all the other brands also report total leak.
Large leak territory on your machine...hard to tell exactly because it varies so much with the pressure and since you are on ASV....potential for a lot of pressure changes with the central treatment but most likely up around 80 or 90 L/min is where your large leak territory is going to begin and maybe a little higher during a big burst of pressure but you won't stay up there very long so I doubt it impacts things too much.

A 32 to 34 or even 40 to 50 L/min leak report from your machine points to leaks being well managed and minimal excess leaking going on.
You could figure out the vent rate from the graph that came with the mask paperwork but it's going to have to be just a guess because the vent rate is tied to pressures and with your machine your pressures can vary depending on how many centrals it is treating.
You can get close though with taking an average vent rate from your 90% pressure numbers. Lots of work and doesn't really mean much except to tell you that maybe you had 5 L/min excess leak. I don't know about you but knowing 35 L/min meant minimal excess leaks would be enough to make me happy and I wouldn't worry no more about it.

[DeeCPAP]

ResMed machines report only excess leak...so all of that 30 L/min is above the vent rate which is called intentional leak.
Mask vent rates at so and so pressure are only useful when total leak is reported. Your machine doesn't report total leak (total leaks is the mask vent rate plus excess leak).
Vent rates are not particularly useful when excess only leak is reported.

I'm gonna guess that is only helpful/useful if the cpap knows which mask is connected and it is the correct mask.

Oh, do you mean if the machine knows if it's a nasal, or FF mask?

[DeeCPAP]

Can you take a quick look at this graph from maybe a week ago? (click it and it enlarges)

Where's it at...I don't see a link?

The links you gave were SUPERB! I'm still reading those pages.

The sample graph I mentioned is one of many, many with many high leaks and low AHI. This one is just a sample, but not the worst: https://imgur.com/gallery/aNc47h8

[Pugsy]

Oh, do you mean if the machine knows if it's a nasal, or FF mask?

Yeah... that's what the mask selection choice is for ResMed machines and why when evaluating leak numbers we want to make sure the correct mask selection has been made.
Vent rates can vary a bit at the same pressure between the mask types...not huge variances but some variance.
When ResMed machines calculate leaks...they remove a generic vent rate based on the mask type selected and pressure used before reporting the excess only leak.
The machine you use does it for you.

Now the vent rate graphs guest mentioned earlier would be useful if trying to figure excess only leak on a Respironics machine or some other machine that didn't do the subtraction for you because those machines don't have a mask selection choice like your ResMed does.
It gets a bit confusing all the ins and outs of this leak stuff and vent rates and excess only leaks.
With a ResMed machine and if the mask selection is correct for the type of mask...the vent rate graphs published in the mask paper work aren't needed because with a ResMed machine we are never told what total leak is or was. We also are never told what the generic number is that gets removed from the total leak so that ResMed reports only excess leak.

If the wrong mask is selected it might throw off the leak numbers a little but in my past experience...it doesn't throw them off in huge numbers and certainly no where near enough to account for the massive leaks that you sometimes get reported.
I know you are good about changing the mask type but even if you forget I don't think we can blame mask type being wrong as the reason for all this big leak or inaccurate data in general.