trialing masks - pressure requirements, What's happening?

[Wondering2]

My wife has been using a F30 mask for some months now. During that time, I have seen (heard) large leaks - or what I assume are large leaks -  sometimes a putt-putt sometimes a loud hum/bussing  - either way enough to wake me!
She sleeps in a recliner, semi reclined, so she is not rolling over side to side, however her head will loll to the side.  Her large leak % (above 24 l/m) bounces around a lot, but averages generally greater than 50% of her sleep time.  So "we" decided to try a different mask (one that I found I was happy with the F20 FFM.

Now I acknowledge that we've trialed this only 4 nights, but the results are puzzling (hence the request for comment). After 4 nights that large leak values have not shifted- still averages >50% -, however there seems to be no noise that arouses either my wife or myself.
But we see a significant change in her pressure requirement, to almost half.  

For many months (with F30) her average 95% pressures have been in the 13-14 cm range. But with the F20 mask, her average 95% pressure has been about 5.5 cm.
AHI has been unaffected by mask change (expected). BTW, 90% of her daily AHI has been Hypopneas with either mask ( I wonder if there is any significance there)

We made no changes is machine settings (5cm-15 cm) and ramp is off, so with the F20 mask the machine is barely adding any additional pressure. 

So,  the questions I'd have are:
1) to what degree do leaks > 24 l/min degrade the performance of the machine to register, detect and respond to adverse changes in breathing? (Is it a waste of time to try to minimize leaks at this threshold value?)

2) Is there a plausible explanation for the significant reduction in pressure required when comparing the two masks?

note: using Resmed Airsense 11 Autoset 5/15 cm, no ramp.

[SarcasticDave94]

We should see an OSCAR report to help see what's going on. Either way, large leaks over the ResMed threshold of 24 L/min means a portion of the therapy is blown out at the area of the leaks. This can and will alter data such as AHI and other events because they're not accurately recorded. Part of the issue is the vent in the mask is the only intended place for the venting process.

[Wondering2]

This report is typical of the F30 mask:
[img][/img]

And is report is typical of the F20 mask:
[img][/img]

Note the dissimilarities in therapy pressures.
 (there were no changes in settings)

Yes, We are working to resolve the leaks, but haven't yet found the solution. so the other part of the question is the degree to which the "system" is degraded as the instantaneous leaks become further away from the 24 l/min threshold.

[dataq1]

I noted somewhat similar, that when I changed types of masks, that the pressures profiles shifted. 
I've got no explanation why.

[Frankiboy]

With such large leaks, it is impossible to make a comparison

[PeaceLoveAndPizza]

To your original questions...

1) to what degree do leaks > 24 l/min degrade the performance of the machine to register, detect and respond to adverse changes in breathing? (Is it a waste of time to try to minimize leaks at this threshold value?)

0 leaks is preferred as that means 100% of therapy is being delivered to the patient. When there is a leak it is likely that no therapy is being delivered (and the machine has no real idea what is going on from an apoenia perspective). Realistically if there are some minor leaks that do not wake the person up and the machine continues delivering therapy, then it is fine.

2) Is there a plausible explanation for the significant reduction in pressure required when comparing the two masks?

You cannot really compare the two given the leaks. 

Not that you need to spend more money, but maybe a different brand of mask may help. Consider getting an F&P Simplus, Vitera, Evora, or other mask (use the chart on their website to be sure of size). 

[staceyburke]

agreed that the leaks make it very hard to tell anything to help BUT flow limits cause the increase in pressure you are experiencing. If we can get the pressure down you may have a lot better luck in stopping leaks. To lessen the flow limits please try setting your machine as following...

EPR full time
EPR 3
Min 7

Try this and post again tomorrow.

[Wondering2]

@Stacy,
Since using the F30 mask, the flow limits are way down and pressures are down.
I'll try to put together a datasheet.
If I failed to mention it, we try a "mask test function" after mask is in place. I'm not clear on exactly how much pressure is applied during this test, but it seems like 10 cm or so. The test always says fit is good. 
later,

[SarcasticDave94]

I think lots of users have problems with the mask fit grinning ghouls. Unfortunately it's a glorified faux cheerleader that isn't very talented or useful. I've had to deal with leaks during my time of being on Apnea therapy. The only way I could track them reliably was in OSCAR.

[Wondering2]

@ Dave: I'm not sure what you mean by the "grinning ghouls", but if you are referring to the smiley/frowney face displays, that's not what I was referring to by the "mask test". The mask pressure test I'm referring to is an application of high pressure. It is a function under "more" options on the Airsense11

I agree about tracking using OSCAR, and I'm probably more impressed with OSCAR trends as compared with a one night snapshot, so here is a summary (also for @ Stacy), shaded is the F20 mask, unshaded is F30 mask :

[img][/img]

At this point in time, it sure looks like there's a difference between the two masks as reflected in the 95%ile Pressure required and the 95%ile Flow limitations. 

The alternate explanation is that "it's all garbage" because the large leaks (especially time above threshold) render the the data unusable.
(If that be the case, I need to have a long chat with the doctor, because the average above threshold for the past two years has been over 30%. ergo the event tracking over the same period is worthless)

BTW, I'm not defending the leaks, I just wish that I could get then under control.