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[CPAP] Reversely proportional Leakage and AHI Values.
#1
Sad 
I have been using my Resmed S9 Auto with H5i humidifier for about a week and I've been fitting 3 kinds of full-face mask (Quattro FX and Ultra Mirage (L) and (M)).

I have gathered information on the usage of these masks and I have observed that the lower values AHI seem to correspond with higher values of leakage and vice versa. So far, I have been getting the best result out of Ultra Mirage (M) with a leakage of 6 to 8 L/min but the AHI values range from 30 to 45. I get a smiley face too on the report every morning so it means I had a good fit last night.

Could someone please enlighten me about this? It's driving me crazy. From what I have extensively researched and thus understand, these two data should be directly proportional to each other.

Thank you! Big Grin

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#2
(02-24-2014, 12:19 AM)Ramen Bear Wrote: I get a smiley face too on the report every morning so it means I had a good fit last night.
Hi Ramen Bear, welcome aboard
Good mask fit means 70th percentile leak is less than 24 L/min
24 L/min is the threshold of acceptable leak, prolong period of high leak rates render the data meaningless

You need to download the software (either ResScan or SleepyHead) so you can see when whats going on, the machine cannot tell whether you were asleep or awake while scoring apnea events, apnea events scored while wake are meaningless too

ResScan and SlepyHead download link (ResScan works with windows, SleepyHead works with both windows and mac computers)
http://www.apneaboard.com/forums/Forum-P...-and-Links

Edit: Followup with your sleep doc
Whats the breakdown category of events (obstructive, hypopnea, central)





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#3
Hi Ramen Bear,
WELCOME! to the forum.!
Hang in there for more answers to your questions and best of luck to you with your CPAP therapy.
trish6hundred
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#4
(02-24-2014, 12:19 AM)Ramen Bear Wrote: ...So far, I have been getting the best result out of Ultra Mirage (M) with a leakage of 6 to 8 L/min but the AHI values range from 30 to 45. I get a smiley face too on the report every morning so it means I had a good fit last night.

AHI of 30-45 is still really high. Successful treatment should have your AHI less than 5.0
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#5
If your AHI is REALLY 30-45 (and not 3.0-4.5) then you aren't getting effective treatment.

That would still be SEVERE APNEA.

All masks leak SOME; they are designed to do that. (This is why Resmed and Respironics have such different critical leak cutoff values: Resmed 'subtracts' out the mask leak and Respironics deals in "total leak" including the mask.)

If the leak is bothering your sleep, it can be within limits and STILL bad and should be fixed.

Otherwise minimal leaks are no big deal.

BUT if the leak is so great that you don't get effective therapy then it must be addressed.

It's possible you need some other type of therapy or machine, but perhaps you just need to fix the leaks.

Since your leaks are minimal at 6-8, get back to your sleep doc for his advice.

Sweet Dreams,

HerbM
Sleep study AHI: 49 RDI: 60 -- APAP 10-11 w/AHI: 1.5 avg for 7-days (up due likely to hip replacement recovery)

"We can all breathe together or we will all suffocate alone."
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#6
The leak number you get from the screen is the 95th percentile leak means leak was at or below this number for 95% of the time (not all night long). The number is useful but should be read in conjunction with the data and graphs from the software

Did you had a sleep study/titration and do you have a followup scheduled with your sleep physician so he/she can see how the treatment is working and if any adjustment is needed.


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#7
(02-24-2014, 12:19 AM)Ramen Bear Wrote: I have gathered information on the usage of these masks and I have observed that the lower values AHI seem to correspond with higher values of leakage and vice versa. So far, I have been getting the best result out of Ultra Mirage (M) with a leakage of 6 to 8 L/min but the AHI values range from 30 to 45. I get a smiley face too on the report every morning so it means I had a good fit last night.
Where are those numbers coming from? The S9's LCD each morning??

As others have said, a machine reported AHI in the range of 30-45 indicates that even with the PAP you are still suffering from severe sleep apnea.

If the leakage number of 6-8 L/min is coming from the machine's LCD, that means that for 95% of the time your leak rate is AT or BELOW 6-8 L/min, which is quite acceptable. Chances are the leaks are NOT what is causing your therapy to be ineffective.

So what could be the problem? Well that depends on the breakdown of events. In the detailed sleep quality report, you should see a breakdown of the AHI. In addition to the total AHI, you should see an AI (apnea index) number and a CAI (central apnea index) number. What do those two numbers typically look like?

If the AHI is usually between 30-45 and the CAI is usually under 5, then chances are the pressure setting is not yet optimized and you may need more pressure to prevent the OAs and Hs from occurring. But if the CAI is really high, and in particular if the CAI makes up 50% or more of your events, then it could be that you are in the unlucky 10% of PAPers who are sensitive enough to the pressure to develop a problem with complex sleep apnea or perhaps your correct diagnosis should have been mixed sleep apnea in the first place.


Quote:From what I have extensively researched and thus understand, these two data (leak rate and AHI) should be directly proportional to each other.
Not really.

Modern machines can and do compensate for reasonable unintentional leaking by increasing the air flow in order to maintain the desired pressure. As long as a therapeutic pressure is maintained, (most of) the obstructive events should be prevented.

But if the leak rates are excessively large (which yours are not) for a long enough time, then the machine can have trouble tracking the breathing pattern correctly and miss events---in other words, when the leak rate is well above 24 L/min, the machine can fail to detect events and this will make the AHI look lower than it actually is. So for folks with really significant leak problems, it's quite possible for there to be an inversely proportional relationship between leak rate and the machine reported AHI.


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#8
Rainbow 
[/quote]
You need to download the software (either ResScan or SleepyHead) so you can see when whats going on, the machine cannot tell whether you were asleep or awake while scoring apnea events, apnea events scored while wake are meaningless too

Edit: Followup with your sleep doc
Whats the breakdown category of events (obstructive, hypopnea, central)
[/quote]

Thank you so much, Zonk. I have downloaded the software and will install it now. I will return to the sleep doctor once I have gathered the data. I will post it here too. Thanks again!

[/quote]
If the leakage number of 6-8 L/min is coming from the machine's LCD, that means that for 95% of the time your leak rate is AT or BELOW 6-8 L/min, which is quite acceptable. Chances are the leaks are NOT what is causing your therapy to be ineffective.
[/quote]

Thanks, Robysue! Now I have a clear understanding. There's only a small leak but it seems that the machine is still not able to resolve my OSA. I would try to gather information from my SD card and I will let you guys know. Thank you so much!

Thank you everyone for welcoming and helping me. Thank you so much.

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#9
Everyone here wants to help A LOT so you are likely going to get lots of answers.

Usually you can only get those leak NUMBERS IF you are running the software so that confused us.

The machine itself doesn't show a "number", just the Green Happy Face or the Red Frowny Face which is much like the "Check Oil" light on an automobile -- once that comes on something is WRONG and needs immediate attention.


You can get the AHI numbers (approximately) from the S9 Autoset display, so with the leak "numbers" thrown in it isn't clear what you are seeing.

In any case, both Rescan and SleepyHead will work for that machine (I use them both) and show you all the detail -- make sure to put your card BACK into the machine each day after you load the data on your computer.

I prefer SleepyHead 9.4.-1 the version called "Nightly" or "Unstable" build -- it's not very unstable and works quite well. If it does crach (about once per week for me) then just restart it.


Sweet Dreams,

HerbM
Sleep study AHI: 49 RDI: 60 -- APAP 10-11 w/AHI: 1.5 avg for 7-days (up due likely to hip replacement recovery)

"We can all breathe together or we will all suffocate alone."
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#10
(02-25-2014, 01:10 PM)herbm Wrote: Everyone here wants to help A LOT so you are likely going to get lots of answers.

Usually you can only get those leak NUMBERS IF you are running the software so that confused us.

The machine itself doesn't show a "number", just the Green Happy Face or the Red Frowny Face which is much like the "Check Oil" light on an automobile -- once that comes on something is WRONG and needs immediate attention.


You can get the AHI numbers (approximately) from the S9 Autoset display, so with the leak "numbers" thrown in it isn't clear what you are seeing.

In any case, both Rescan and SleepyHead will work for that machine (I use them both) and show you all the detail -- make sure to put your card BACK into the machine each day after you load the data on your computer.

I prefer SleepyHead 9.4.-1 the version called "Nightly" or "Unstable" build -- it's not very unstable and works quite well. If it does crach (about once per week for me) then just restart it.

Hello, Herbm! Thanks for replying.

I found out that if I hold down the info button + the check marks button = I would get another tab which contains a more detailed report. One of the info there is the leak in L/min. I can also see from there AI and CI, though I don't know yet its importance.

Is it easy to download Sleepyhead? Resmed wouldn't allow me to download ResScan. Thanks to Zonk's link I'm able to get it.
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