APAP and leaky masks?

So after about a year of straight CPAP (at pressure of 8), I decided for a number of reasons to switch to APAP, so I've had my PB420e for 3 nights now. I have it set at 4-12.

Night 1 was OK. I used a Breeze and got pretty steady pressures with a high of 8 and a "recommended" of 7.

Night 2 was bad. I used my Ultra Mirage nasal and after a few hours, it spiraled up from 4 to 12 and I woke up with my mask leaking and howling. The "Runs" and Cycle states were also very erratic.

Could this be the machine trying to compensate for the mask leaks? Was the mask just leaking because of increased pressure since the machine was upping the pressure for another reason? I don't the machine was reacting to a "real" condition...

Night 3 was straight CPAP at 8 with my Activa...

I can post an image of the interesting parts of the graph ... if I can figure out how to...


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Had something similar happen with my Remstar. On the Encore software you can see the leak graph and it correlated to the increase in pressure. Once the mask stopped leaking tho, it almost blew me across the room at 15!! (I have since limited that so it won't happen again!)

OK, here's an image of the interesting bits of the graph:

My take is the pressure runaway is related to excessive flow runs rather than excessive leak. The elevated leak rate is a response to the runaway pressure.

Try turning IFL1 off.

-SWS, that would be my take on it too. WOW that's a lot of flow limited runs. Those would not show up it it were just mask leaks because that would read the opposite of a limited flow.

UKWIS, do you have some airway resriction? Heavy nasal congestion? Badly deviated septum? Cotton in your nose?

Can you post a graph from a night that you felt was a "good" one so that we can compare?

SWS and Muck, thanks for looking...

I don't have any real airway restriction. I am getting through a cold with congestion, although I actually used Afrin on the bad night, so I was pretty "clean". No cotton; since the mask was on, I couldn't get a finger in there either.

I posted an image of night 1 and night 2 externally:

http://www.nwlink.com/~jtn/JimAPAPBig.jpg

UKWIS,

-SWS is right, try turning IFL1 off, For some reason the machine is registering a huge amount of flow limited runs for you. The other stuff looks very good. The leaks, as -SWS said, do look as though they are resulting from the pressure run and not causing it. Looks as though your AHI was very low for the 12 hours shown on the graph.

Wader, I'll try turning IFL1 off.

I'm still not very clear on "flow limited runs". Basically 2 or more times where my inhalation isn't as deep as "it should be"??

Aside from any technical definitions, most of those tick marks on the "run" line of the chart should not be there. That line should look similar to the rest of the data, just a mark here and there.

Night 4... I turned IFL1 off, used a Breeze and felt like I got a pretty good night's sleep. My pressure stayed around 5-6.

Here's my chart for the nite: http://www.nwlink.com/~jtn/JimNight4.jpg

However, the 166 Runs, 20% of the cycle marked as flow-limited (75% normal, 5% intermediate) confuses me.

I don't really know what the "Cycle" and "Runs" are measurements of and what could account for these large numbers when the number of apnea events is very low and overall pressures don't get pushed up very far. Can anyone explain why this might be happening?

What should I do about all the flow-limited cycles? Even though the apnea events are low, should I raise my range low value from 4 to try to lower the occurance of "Runs"?

Hep me Rhonda, Hep, Hep me Rhonda...[/url]

A "flow run" would be several breaths, each with "flow limitation". A "flow limitation" is not a specific type of airway obstruction/constriction/collapse/restriction. Rather a "flow limitation" merely describes the final breath waveform shape and volume that exits your mouth and enters the 420e sensors. A "flow limitation" is a lesser obstructed breath than a hypopnea or apnea. A "flow limited" breath can be the result of a swollen nasal passage, a slight asthma, a mildly sagging pallate, etc. The 420e has no way of knowing what physiological mechanism accounts for that slightly limited breath that it measures---only that it is slightly limited. Thus it is a "flow limitation" and several such breaths are a "flow run".

The 420e will try to correct "flow runs" with air pressure exactly as an AutoPAP is designed to endeavor by algorithm. However, some flow limitations cannot be corrected by air pressure. The AutoPAP algorithm should ideally recognize when it is running away with pressure to unresponsive "flow runs," but unfortunately this is not always the case. With that said, your "flow runs" that cause your 420e to over-trigger might entail one of these scenarios:

1) pressure unresponsive flow limitations
2) pressure aggravated flow limitations
3) pressure responsive, yet algorithmically "deceiving" flow limitations
4) misdetected sleep events (not really obstructive flow runs)

Your additional data with IFL1 off seems to hint at your case not being scenario 2 above: you still had many runs despite your AutoPAP pressure staying low. If you slightly elevate your bottom AutoPAP pressure as you suggest (while leaving IFL1 off), then you can note whether the number of runs diminish. If so, then yours would be a case of scenario 3---whereby you proactively eliminate your flow-limited breaths with elevated pressure, yet you leave IFL1 off so as not to continue over-triggering with a deceptive breathing pattern regarding "flow limitations".

However, if you slightly elevate your minimum pressure in that manner and notice no reduction in "flow limited" breaths, then you might assume either scenarios 1 or 4 are the case. Some flow limitations are pressure-unresponsive, and therefore should not be treated with air pressure. If your outstanding "flow runs" result in neither desats nor sleep disturbances, then they may be of absolutely no consequence to you. However, you still might want to have your primary physician or a pulmonologist evaluate you for other airway disorders. Scenario 4 is an algorithmic possibility as any programmer knows, but somewhat less likely in my own guesstimation. Rested Gal believes that she may experience "shallow breathing" that tricked her 420e in this manner----and I have to agree that's a definite possibility.

Thanks a million for the insight SWS. Very informative. I'll do some testing.

Appreciative in Seattle.

I have a folder in my computer labeled "Apnea". In that folder is a sub-folder labeled "SWS". That beautiful post above, explaining flow runs and flow limitations, is now duly copy/pasted into the folder - along with sooo many posts by that modest, caring man over the past year.

Every sleep tech, every DME, every RT, (every sleep doctor, for that matter) should study his posts in the same way they used to study their textbooks. And every autopap user who is the least bit interested in learning how to take a proactive role in his/her own treatment should do the same. Just think what knowledge about your own sleep can do to assist your doctor in helping both of you together arrive at your best treatment. The message boards are an education in so many ways.

-SWS,

Thanks again for the tips. I raised my min pressure from 4 to 6. Pressure stayed at 6 almost all night and my "runs" dropped to 70 from 166 with the cycle stats going to 89% Normal, 3% intermediate, 8% flow-limited. It looks like your theory about "scenario 3" is probably right. Glad somebody knows what they're doing around here!!

Thanks for helping us sort out these numbers. As RG (Rotweiler Gal?) said, your participation and willingness to help educate those of us trying to understand our condition and treatment is very, very much appreciated.