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Why does my Pressure and Leaks go crazy
#1
Here are a couple examples of bad nights.Oh-jeez I don't know if the leaks cause the presure to rise or if te presure causes the leaks.Huh I am not aware of either until I look at Sleepyhead. I have been experiencing some nasal congestion more than my normal chronic congestion.
Yes, I know some of you would kill for bad nights like mine. After my first 0 AHI a week or so ago, I know I can do better.


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#2
Most of your events are hypopneas. I think events like that cause the pressure to rise, which of course makes leaks more likely.

I don't think leaks can cause pressure rises.

Have you tried nasal irrigation? Chin strap?
Sleepster
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#3
I have been using a chin strap on both nights in question and every night.
No have not yet tried irrigation. I am afraid my garden hose will make a mess in the house.
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#4
I don't know this machine, but what grabs my attention is the stark difference between your epap and your ipap on the charts. Or, more to the point, off the charts... I notice that when your epap and ipap are closer together, which they are at times, your ahi goes to next-to-nothing, your leak rates are great, and all is right with the world.

It looks to me that the max pressures are too high. But, before you change them, get some opinions from those that know more about this machine than I.

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#5
bwexler,

Your equipment is listed as a PRS1 BiPAP AutoSV Advanced.

So I presume you were diagnosed with either central sleep apnea (CSA), complex sleep apnea (CompSA), or mixed sleep apnea (MixedSA) and a high number of central apneas on one or more sleep tests.

And your PS is set to range from 1.8 to 18.3?? (That does not quite make sense to me, since it's an awfully wide PS range.)

The way your machine treats central apnea problems (which may very well include those residual hypopneas) is that when your breathing is not "up to snuff", the machine cycles between EPAP and IPAP at a fixed interval (instead of waiting for you to inhale) AND it bumps the IPAP up (by a lot) while leaving the EPAP basically alone. The machine will think you are in need of triggered inhalations when the minute ventilation numbers drop below a certain threshold and/or the respiratory rate drops below a certain threshold. (Those thresholds are at the heart of the ASV algorithm and they do use target values that are set using the last several minutes of "normal" breathing if I recall.)

I don't understand how JediMark does the "patient triggered breathing" statistics because I don't use an ASV and I also don't recall how the "patient triggered breathing" data is presented in Encore, except that it is a GRAPH. But my guess is that during the times when your IPAP is in those really super high areas, the machine is doing most of the "breathing." In other words, the times when your IPAP is sky high are the times when machine is triggering a lot of inhalations because it is not happy with how you are breathing.

(07-11-2014, 01:40 PM)bwexler Wrote: I don't know if the leaks cause the presure to rise or if te presure causes the leaks.Huh
The pressure increase is causing the rise in the Total Leak graph, and MOST (but not ALL) of that rise is not a sign that you've got massive unintentional (or excess) leaking going on.

We'd expect a big, big increase in the total leak graph with that big, big increase in IPAP pressure: Total leaks go up as the pressure goes up because the intentional leak rate for the mask goes up. The intentional leak rate for many nasal masks at 10 cm is around 30-35 L/min, but at 20 cm the intentional leak rate is around 50 L/min. So the plateaus in the Total Leak graph that are around 56 L/min may just represent ordinary, intentional leaking.

The higher spikes? Well, it's pretty hard to maintain a seal on a mask when the pressure is jumping back and forth between an EPAP = 10-12mc and an IPAP = 25cm. That's a 13-15cm increase in pressure on every (triggered) inhalation. And that's enough of a change in pressure to cause some problems with mask stability. In other words, your mask may be being blown around by all that extra pressure and that triggers additional excessive leaks during the IPAP periods. (And it does look like the BiPAP is measuring the leaks during IPAP and not EPAP here.)

Now it's also quite likely that when your upper airway gets slammed with those repeated IPAP = 25cm triggered inhalation that that you are opening your lips (even with the chinstrap) in response to a lot of air suddenly being inside the oral cavity. And that allows a lot of air to unintentionally leak out the mouth. And that's probably the cause of the largest peaks in the Total Leak Graph.

It's also worth pointing out that since you are using SH 0.9.6 and a PR System One ASV, if there were any Official Large Leaks flagged by the machine, you'd have a LL line in the event table and gray shading on the Flow Rate curve during the large leak. So as huge as these leaks look, the machine felt that it was having no serious problems maintaining the required pressure.

A final note: The PR auto algorithms will DECREASE pressure in an official Large Leak in an attempt to "fix" the leak.
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#6
(07-11-2014, 01:47 PM)Sleepster Wrote: Most of your events are hypopneas. I think events like that cause the pressure to rise, which of course makes leaks more likely.

I don't think leaks can cause pressure rises.

you are correct on that, good sir... the more modern machines actually try to *lower* pressure in response to excessive leaks, in an effort to get the mask to reseal.

Robysue did a nice post on it somewhere.

that said, those leaks aren't bad for that high a pressure, the vent rate on most masks is around 60 at 25cm.
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#7

"Your equipment is listed as a PRS1 BiPAP AutoSV Advanced. "

Yes it is the DS960TS.

"So I presume you were diagnosed with either central sleep apnea (CSA), complex sleep apnea (CompSA), or mixed sleep apnea (MixedSA) and a high number of central apneas on one or more sleep tests."

Yes. that is why I was switched from my S9 Autoset

"And your PS is set to range from 1.8 to 18.3?? (That does not quite make sense to me, since it's an awfully wide PS range.)"

I agree, but I am not knowledgeable enough to know what changes would be appropriate. Any recomendations ar welcome.
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#8
(07-11-2014, 02:18 PM)retired_guy Wrote: I don't know this machine, but what grabs my attention is the stark difference between your epap and your ipap on the charts. Or, more to the point, off the charts... I notice that when your epap and ipap are closer together, which they are at times, your ahi goes to next-to-nothing, your leak rates are great, and all is right with the world..

it's an ASV, that's what it's designed to do.
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#9
(07-11-2014, 03:45 PM)diamaunt Wrote:
(07-11-2014, 02:18 PM)retired_guy Wrote: I don't know this machine, but what grabs my attention is the stark difference between your epap and your ipap on the charts. Or, more to the point, off the charts... I notice that when your epap and ipap are closer together, which they are at times, your ahi goes to next-to-nothing, your leak rates are great, and all is right with the world..

it's an ASV, that's what it's designed to do.

Please share your expertise with the OP. I don't have this machine so I don't need to know it's designed to have huge spikes causing massive leaks.
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#10
(07-11-2014, 04:29 PM)retired_guy Wrote:
(07-11-2014, 03:45 PM)diamaunt Wrote:
(07-11-2014, 02:18 PM)retired_guy Wrote: I don't know this machine, but what grabs my attention is the stark difference between your epap and your ipap on the charts. Or, more to the point, off the charts... I notice that when your epap and ipap are closer together, which they are at times, your ahi goes to next-to-nothing, your leak rates are great, and all is right with the world..

it's an ASV, that's what it's designed to do.

Please share your expertise with the OP. I don't have this machine so I don't need to know it's designed to have huge spikes causing massive leaks.
I was just offering the bit of information for you, so you'd know more the next time someone asks a similar question.

Robysue's answer went into very good detail, (as hers always do) and i'd just be repeating it.... and, as she points out, those aren't massive leaks, they're quite normal for the most part, check your mask and see what the leak rate is for 25cm pressure, the ones I have here show about 55lpm normal leak.
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