High leak rate but low AHI

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lastmango
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High leak rate but low AHI

Post by lastmango » Mon May 21, 2018 6:25 am

Hi all,

After struggling with full face masks for some time I switched to nasal pillows with a chin strap a year or more ago. Being a mouth breather I was hesitant but it has worked out very well! However, I’ve noticed that my leak rate is high, according to the machine, at about 35, but my AHI’s have averaged only 1 or 2 at most since the change. I sleep well, and feel pretty rested, but is the leak rate an issue? Am I not receiving the full CPAP therapy benefit?

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ChicagoGranny
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Re: High leak rate but low AHI

Post by ChicagoGranny » Mon May 21, 2018 6:34 am

Are you using Sleepyhead software?

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Pugsy
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Re: High leak rate but low AHI

Post by Pugsy » Mon May 21, 2018 6:45 am

ResMed machine reported leak rates (what you see on the machine's LCD screen) is what we call a 95% leak number.
What that means is that for 95% of the time you were at OR BELOW that leak number. It is NOT an overall average where you spent the bulk of the night in terms of leak.

You probably has a small portion of the night where the leak was above 35 L/min but we don't know how far above you went. We know only 5% of the night.

You also don't know how much time might actually have been spent below the ResMed large leak threshold of 24 L/min.
Might have been 80% of the night you were below 24 L/min. Might have been 50% of the night.
95% numbers are easily skewed to the high side with a relatively short period of time at the higher numbers (leaks or pressure).
For that reason I don't panic when I see a 95% number that might be a bit scary. Instead I use available software to see exactly what the leak was doing and for how long it might have been doing whatever it was doing and then I decide if there is a big problem on not.

FWIW though...ResMed machines are still fairly accurate in their sensing and reporting and responding up to leaks in the 35 to 40 L/min range. Above that and we start worrying about accuracy.
And remember that the accuracy only pertains to the actual time in really large leak...example...supposed someone spends 15 minutes at leak level 38 L/min but the rest of the time it maybe never goes above 30 L/min. Only the 15 minutes comes into question in terms of accuracy or did the machine miss something. 15 minutes out of 7 hours of sleep isn't going to mess up the data reported much at all.

Here's a thread where I show examples of why that 95% leak number doesn't always reflect how the entire night went and why I don't get all in a panic over a number off the machine's LCD screen no matter how ugly it might initially seem.
viewtopic.php?f=1&t=108724&p=1036669&hi ... t#p1036669

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lastmango
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Re: High leak rate but low AHI

Post by lastmango » Mon May 21, 2018 10:19 am

Thank you for the detailed response, helpful to know that apparently that the leak rate was the peak for the night. I do have the Sleepyhead software but haven’t used it in awhile because things have been going well. I will dust it off and take a look.

As a side note regarding the Airfit P10, it seems like after so many complaints about the non adjustable strap that it would have been reengineered by now!

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robinfre
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Re: High leak rate but low AHI

Post by robinfre » Tue May 22, 2018 2:18 pm

I use the P10 nasal pillows and right now my leak is at 31%. There are times when it goes down to 22%. All my other stats are very low. Should I be concerned? I once went to my provider (Apria) when it went to 30% but the respiratory therapist I saw told me not to worry about it unless it goes past 40 or 50%. And I do change the pillows about every 3 weeks. I also sleep on my side. Should I be concerned?

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BTS
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Re: High leak rate but low AHI

Post by BTS » Tue May 22, 2018 7:24 pm

lastmango wrote:
Mon May 21, 2018 10:19 am
As a side note regarding the Airfit P10, it seems like after so many complaints about the non adjustable strap that it would have been reengineered by now!
Complaints? No reason for a redesign on the P10 I think it's perfect as is and hope it stays this way... No use messing with something that just works and is so low profile...

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Last edited by BTS on Tue May 22, 2018 7:34 pm, edited 1 time in total.

TedVPAP
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Re: High leak rate but low AHI

Post by TedVPAP » Tue May 22, 2018 7:34 pm

robinfre wrote:
Tue May 22, 2018 2:18 pm
I use the P10 nasal pillows and right now my leak is at 31%. There are times when it goes down to 22%. All my other stats are very low. Should I be concerned? I once went to my provider (Apria) when it went to 30% but the respiratory therapist I saw told me not to worry about it unless it goes past 40 or 50%. And I do change the pillows about every 3 weeks. I also sleep on my side. Should I be concerned?
Welcome to the forum. Please start a thread so we can focus on your issues. I am confident that we can help you.

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palerider
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Re: High leak rate but low AHI

Post by palerider » Tue May 22, 2018 7:35 pm

robinfre wrote:
Tue May 22, 2018 2:18 pm
I also sleep on my side. Should I be concerned?
First thing you should do is read the data off whatever machine you have.... and get some *real* leak numbers, instead of the meaningless percentages you're getting from somewhere. it'll tell you way more.

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BTS
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Re: High leak rate but low AHI

Post by BTS » Tue May 22, 2018 7:37 pm

robinfre wrote:
Tue May 22, 2018 2:18 pm
I use the P10 nasal pillows and right now my leak is at 31%. There are times when it goes down to 22%. All my other stats are very low. Should I be concerned? I once went to my provider (Apria) when it went to 30% but the respiratory therapist I saw told me not to worry about it unless it goes past 40 or 50%. And I do change the pillows about every 3 weeks. I also sleep on my side. Should I be concerned?
Changing the pillows every 3 weeks is a little excessive IMO.. With the leaks perhaps you need a chin strap?

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