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Leak rate and Apnea
#1
I have had cpap since 9/17/14, and my AHI has been usually around 14-18, but spiking higher. That is actually a third of what I tested out at original sleep study. My Dr. changed me from auto to fixed, set at 14, about a week ago, because I have not been sleeping, due to pressure increases waking me up. I have seen some improvement. Still running around 12, but it seems to be mostly in a cluster, or two lasting 45-60 minutes each, and the rest of the time it is really pretty much uneventful. Were it not for that one cluster last night, average would have been VERY low. I have noticed that my air leaks are generally low, average .06-.32%, over the last month. But during those clusters I mentioned, the leak rate spikes at same time, at each individual event, mostly OA. Flow rate shows drop every event, which I would expect. Going all the way down the page, everything else shows increase, as well. If I am at constant pressure, why would the leak rate increase during those events? Thanks for any help understanding.
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#2
This is a wild guess so take it as such. One either the leak starts first and the OA happens right after. OR, an OA is blocked airway.

If you have x set number of pressure going in and out and suddenly that flow is blocked off by the OA the intentional leak rate of the mask is going to shoot up to compensate and hold that x set number in pressure, instead of the thing just building up to 20 cm or whatever higher.

That will add to your total leak rate. Plus if you spring a an additional leak around the seal while its blocked it maybe be even higher.

Just a thought as to why it correlates with your OAs Most of the OAs I have are toward morning also though Im not sure exactly why.
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#3

On your Resmed, the leak rate is not a percentage, but rather a "number of liters" thing. It needs to stay below 24, preferably well below, or any results can be meaningless. In other words, if you turned over in the night and knocked your mask c**k-eyed for awhile, the leak rate could really go up dramatically, and the results could be goofy because of that.

I'm not keen that your doc changed you from auto to cpap because you couldn't handle the pressure changes. I really think not handling the pressure changes has more to do with other things. So... Are you using the EPR feature? If so, at what value? Are you using the "Ramp" feature? What are it's settings? Be aware that while on "Ramp" your Resmed will not report or treat any apnea events. So if your on ramp for 45 minutes for instance, and you restart your machine during the night because you had to go to the bathroom, that would amount to 1 1/2 hours without treatment.

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#4
(10-24-2014, 04:18 AM)saltydawg2 Wrote: My Dr. changed me from auto to fixed, set at 14, about a week ago, because I have not been sleeping, due to pressure increases waking me up. I have seen some improvement. Still running around 12, but it seems to be mostly in a cluster, or two lasting 45-60 minutes each, and the rest of the time it is really pretty much uneventful. Were it not for that one cluster last night, average would have been VERY low.
More likely the cluster in rem sleep or/and rolled on your back. The tennis ball trick might helps preventing from rolling on your back
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#5
(10-24-2014, 01:52 PM)Ghost1958 Wrote: This is a wild guess so take it as such. One either the leak starts first and the OA happens right after. OR, an OA is blocked airway.

If you have x set number of pressure going in and out and suddenly that flow is blocked off by the OA the intentional leak rate of the mask is going to shoot up to compensate and hold that x set number in pressure, instead of the thing just building up to 20 cm or whatever higher.

That will add to your total leak rate. Plus if you spring a an additional leak around the seal while its blocked it maybe be even higher.

Just a thought as to why it correlates with your OAs Most of the OAs I have are toward morning also though Im not sure exactly why.

Sorry ghost, the physics just does not support your theory.

He's running constant pressure not constant flow. Air is a compressible gas. Now if it were a fluid, then the "hammer" effect would be in play -- but it's not.
This Veteran is medicated for your protection.
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#6
Thanks for moving this thread. Don't know how I messed up at 4:30 this morning... EPR is set on 3. Tried 2, but timing seemed off. Leak rate is generally below 2-3, much less over 24. Probably looked at the wrong set of numbers on Sleepyhead. Thought the ramp was set, but starts off 14, and stays there. Very hard for me to sleep on my sides: my arms fall asleep before I do. I have slept very irregularly in the last month, and wanted the Doc to help me get sleep. He did not really want to change it, he said, but he was trying to help. May change it back after compliance stage, but no need to alienate the good doc, over my request. Used a chin strap for the first time last night; probably would have had less dry mouth had I not eaten ham for supper, huh? Worked well. Last night AHI was under 8, and the best so far for 6 hours of sleep since starting. The one cluster was around 11 or so, and was at least 80% of the night's events; before and after that it was almost all clear airway apnea. Thanks for all the responses, and suggestions.
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#7
(10-24-2014, 04:03 PM)justMongo Wrote:
(10-24-2014, 01:52 PM)Ghost1958 Wrote: This is a wild guess so take it as such. One either the leak starts first and the OA happens right after. OR, an OA is blocked airway.

If you have x set number of pressure going in and out and suddenly that flow is blocked off by the OA the intentional leak rate of the mask is going to shoot up to compensate and hold that x set number in pressure, instead of the thing just building up to 20 cm or whatever higher.

That will add to your total leak rate. Plus if you spring a an additional leak around the seal while its blocked it maybe be even higher.

Just a thought as to why it correlates with your OAs Most of the OAs I have are toward morning also though Im not sure exactly why.

Sorry ghost, the physics just does not support your theory.

He's running constant pressure not constant flow. Air is a compressible gas. Now if it were a fluid, then the "hammer" effect would be in play -- but it's not.

Like I said. Wild guessThinking-about. Dont-know:grin:

Im a hillbilly the only physics I know about is reloading ammo and a walnut falls down instead of up Laugh-a-lot

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#8
(10-24-2014, 11:45 PM)Ghost1958 Wrote: Im a hillbilly the only physics I know about is reloading ammo and a walnut falls down instead of up Laugh-a-lot

No disrespect intended... and BTW, I reload also.
This Veteran is medicated for your protection.
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#9
Well if you didn't fire the darn things you wouldn't have to reload........
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#10
Last night, I really had no "clusters" of apneas, but those I had still shows leak peaks. My AHI was under 7, which was a record low for me, especially for almost 8 hrs. of sleep. I for the first time had more Central Apneas than Obstructive. A few more nights of sleep, and I will consider that an issue.
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