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Do large leaks affect AHI numbers?
#1
My AHI is always below 1, but last night it went over 2, for the first time ever (2.62). At the same time, SleepyHead reported "significant period of major mask leakage" (4 minutes and 14 seconds). I don't know what happened, as I normally do not see these large leaks, with a few rare exceptions.

My question is: do these large leaks count towards total AHI, or is AHI calculated only based on clear airway and hypopnea events?
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#2
Large leaks are not included in the AHI calculation.  4min, 14 seconds is not a very long period. We all have occasional bad nights. My AHI is normally less than 1 but last night it was 2.5. It's clear from the graphs that I had more flow limitations than usual. I suspect I moved around more than usual.
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#3
events detected during large leaks do count toward AHI.  The ability to detect and classify events lessens the further over the limit you go.

An to the second question NO!!!.  Generally Obstructive events are the most common,  if all you are seeing are clear airway and hypopnea events you need your charts to be evaluated!!!  Though at the levels you are reporting I don't believe you are having any issues.

Need to view your charts though to make a true evaluation of your leaks.  The numbers themselves do not tell the whole story
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#4
(03-18-2017, 02:03 PM)bonjour Wrote: events detected during large leaks do count toward AHI.  The ability to detect and classify events lessens the further over the limit you go.

An to the second question NO!!!.  Generally Obstructive events are the most common,  if all you are seeing are clear airway and hypopnea events you need your charts to be evaluated!!!  Though at the levels you are reporting I don't believe you are having any issues.

Need to view your charts though to make a true evaluation of your leaks.  The numbers themselves do not tell the whole story

Here's the chart from yesterday. All of these large leaks happened during my pretty long afternoon nap.

[Image: j5SyGdC.png]
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#5
By the numbers, you do NOT have a large leak problem.  You can right click on the Leak Rate chart (left side) and under dotted lines click "Leak Rate Upper Threshold"  That will put a line across your chart that except for spikes, you should be under.  Even then it depends on time over threshold.

Unless you are feeling the leaks and they are disturbing your sleep, they are not an issue.

If they are be specific about where they are (into the eyes)  and anything you think you may have done to cause it,  Pull on the hose when I rolled, getting up to relieve myself, etc.
We can work on that but we would have have an idea on what is bothering you.
New to Apnea? Helpful tips to ensure success
Including Understanding Sleep Apnea, New to Sleep Apnea-the process, Rx, Machine Choices, Optimizing Therapy, SleepyHead, posting charts, more

Mask Primer
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#6
How did you arrive at the present settings? Esp: Why ERP=3? With IPAP = 7.8, that gives an EPAP of 4.8. 4.8 will not hold a nasal pillow against your nostril.
That's why you're leaking. EPAP is also the pressure that holds off flow limitation and snore -- you have plenty of flow limitation and snore. Unless there is some unusual reason for EPR=3, you probably shouldn't have it on.

what's with the big therapy gap from 19:15 to 04:14 ?
[Image: 1F4m9Ift.jpg]
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#7
Bonjour, thank you for the threshold line tip.

I am not worried about leaks, at least for now. It's just that the SH welcome screen was reporting significant periods of major mask leakage, and for the first time ever my AHI was above 2, almost 3. I know it's still a good number, but it was around 300%-400% higher than what I'm normally seeing. I thought that maybe the time during these large leaks contributed to this higher AHI. Thank you for clarifying.


(03-18-2017, 04:33 PM)justMongo Wrote: Why ERP=3?  With IPAP = 7.8, that gives an EPAP of 4.8.  4.8 will not hold a nasal pillow against your nostril.

My understanding is that EPR helps with exhaling, increasing the overall comfort for the patient. I've set it up to its maximum value, and it could be an overkill. Honestly, I do not see a lot of leakage, at least not over the threshold, but maybe I can follow your advice and drop the EPR to 2, or 1.

Thanks, guys.
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#8
Well, let's look more closely. You masked up and started at: 16:16 hours. You awakened at 06:48. That's over ten hours. But, you got credit for only 5.44 hours. Why? either, you shut down OR, the machine shutdown for you. Why? If you have auto start stop set to ON, then a large leak can make the machine believe you took the mask off, and the blower shuts off. Can I prove that's what happened? No, I wasn't there. I would suggest you turn autostart/stop to off.

Yes, EPR is a comfort feature; but it must be used with some understanding of it's impact. It's seldom needed for pressures below 10 to 12. At very low pressures, it's a detriment to therapy because it drops IPAP too low to hold seal; and causes snore and flow limitation. At 7.8, EPR at most 1 or off.

And, you see those few CSs when you first start out. Too much EPR can cause CO2 washout; and induce CA.

Those who need a wide split between IPAP and EPAP should be on bilevel. (i.e. -- VPAP or BiPAP) I don't see you in that category.

I think with two changes, autostart/stop=OFF and EPR=OFF, you can do so much better. Even your leaks should improve as the nasal pillow will not relax against the nose and lose seal.

Kind Regards,

Mongo
[Image: 1F4m9Ift.jpg]
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#9
(03-18-2017, 09:44 PM)justMongo Wrote: Well, let's look more closely.  You masked up and started at: 16:16 hours.  You awakened at 06:48.  That's over ten hours.  But, you got credit for only 5.44 hours.  Why?  either, you shut down OR, the machine shutdown for you.  Why?

The answer is very simple, and not too hard to guess. I took a long 3-hour nap in the afternoon, woke up just after 7 pm, and did not go back to bed until 4 am. So, those were 2 independent sleep sessions. There is no autostart/stop.

As for EPR, I think I'll drop it down to 1 for now and see how that works.

Thanks for the feedback.
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