Change in mask = change in AHI??

Ashkat · Post by **Ashkat** » Wed Feb 20, 2008 9:52 am

I went from the Swift II to the Liberty a few weeks ago because I thought I was mouth breathing. My RT (who is actually a GOOD one) said my leak rate didn't indicate mouth breathing, but that she'd definitely fit me with the mask. So I've been using the Liberty these past few weeks with excellent results. I had GOOD results with the Swift, but I had GREAT results with the Liberty. Yesterday I noticed a sore spot by my lip were the Liberty rubs. So last night I used the Swift to give my face a break from the pressure of the Liberty mask. I went from AHI of less than 1 to an AHI this morning of nearly 10! AI of 6.6! My leak rate was still reasonable, slightly higher than usual with the Liberty, but it took me some time fiddling with the mask to get it situated before bed, so I'm sure that played a part. Leak was about .5.

It may be a fluke, I'm going to keep wearing the Swift for another week or so until this sore spot heals, so I'll be reporting on future results.

Has anyone else experienced something similar?

~Ashkat

sleepie · Post by **sleepie** » Wed Feb 20, 2008 10:05 am

same thing here,,i thought i would go to a full face mask in case of mouth breathing--was using nasal mask---i tried 3 different masks full face and my numbers were always up--i went back to the nasal--i never realy found out why---someone here said that different masks need different pressures--after 6 months of getting my average down to less than 1--i did'nt want to do that all over again with a new mask ---so i abandoned the project----hope someone here can help us--i would rather not take any chances with mouth leaks---since i have to wear a mask anyway,,might as well be the one that eliminates all leaks----just my thoughts------pat

HelpMeBreath · Post by **HelpMeBreath** » Wed Feb 20, 2008 2:16 pm

Can the AI be effected by leaks? I recently switched from a Swift II to a hybrid, I didnt change the mask type in my machine however because Im not sure what the Hybrid is called.

I am also a mouth breather.

Ashkat · Post by **Ashkat** » Wed Feb 20, 2008 2:25 pm

I really appreciate the comments so far!

Something else that I realized after posting initially is that the RT changed my pressure from 10 to 8 in the same visit that she fitted me with the Liberty. I've never been on the Swift with a pressure of 8. I'm currently at 9 because 8 just felt like too little air to breath. Maybe 9 isn't sufficient pressure to fully treat the apnea. The Swift is the mask I titrated with at my second sleep study, so the pressure data should be accurate with a titration of 10.

I'm going to sleep a few more nights with the Swift at my current settings to see if there are any patterns to the data and how they compare to the Liberty at 9. After that I think I'll try going back up to 10 with the Swift if I'm still having a higher AHI than I'd like.

~Ashkat

dutchbrown · Post by **dutchbrown** » Wed Feb 20, 2008 4:04 pm

Empirical data seems to be that different masks need different pressures to reach the same effect, probably due to the configuration and the route the air has to take to get to the back of your throat. Because it is moving air (versus stagnant, in which case the pressure would stabilize throughout), the pressure drops based on the contours and distance from the machine ... which is different per mask. Higher leak rates would, theoretically, make the pressure drops more severe (higher air velocity).

However, that all said, it seems to be very particular as far as what pressures, masks, machines, etc as to how MUCH difference there is for "optimum" pressures. With me, the difference seems to be about 1-2cm difference between a Quattro FF and a ComfortGel Nasal with the Respironics M-series. I would think the difference would be much less if you were just switching the same STYLE of mask (i.e. from one nasal to another nasal). I would also think the nasal pillow styles would have some of the biggest differences because of the "orifice" nature of the interface with the nose.

Ideally, you want to have your sleep study or titration done with the mask you are using long term. If you use two different masks (like I do, with a FF mask for the times when my allergies are acting up, which happens often) you might want to ask your DR if you can use each mask for half the night and have them figure out the optimum pressure for each.

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sleepie · Post by **sleepie** » Thu Feb 21, 2008 7:37 am

thank you very much mr dutchbrown--i now know whats going on and will try an increase in pressure when i give the full face another try,,this has helped me a great deal---thanks again for explaining why this happens---pat

Ashkat · Post by **Ashkat** » Thu Feb 21, 2008 2:17 pm

Last night I got home, exhausted, from an exceedingly long day at work and just couldn't stomach the thought of another night without the low numbers I get normally. So I bumped the pressure back up to 10, since I know it works well. Numbers were much better today, and I had a much easier time sleeping with the Swift than I do with the Liberty. There's just so much more mask to make room for when trying to snuggle up with a pillow!

Overall, I'm quite happy with both masks. The Liberty feels much more secure on my face, gives great treatment at a lower pressure, and still allows me to put on my glasses if I need to see the clock. The Swift is very freeing, I can sleep in most of my usual positions and I don't feel as if I'm getting ready to go scuba diving when I put it on.

I think I'll stick with the Swift for now, and keep the Liberty as my back-up mask. When I get the chance I'm really looking forward to checking out the headrest/aura/twilight/whatsitsnamenow. It looks like it's a really comfortable mask to wear, and the vent goes UP instead of OUT.

~Ashkat

hades161 · Post by **hades161** » Thu Feb 21, 2008 6:52 pm

I also went from a Swift II to a Liberty. I currently use a pressure of 17 and I found that with the Swift II this was good with AHI being in the sub 1.5 area with a low of 0.7. When I switched I found a funny thing happen to my numbers I jumped up to an AHI of 3.5. I was remiss at so high a change and so many more events so I went back to Apap with a range of 16-20 and found that the Swift II was typically using 1 or 2 CM more to get the job done then the Liberty.

The leak rates were about the same but the leak pattern was very different. The Swift II was peaks and valleys, where the Liberty was more flat line. For me the change from the 2 was like a big splash in a little pond. I am currently trying to nail down a few more issues with my treatment with labs tests and might need a bi-pap. But I found the difference in the 2 masks to be very disconcerting. I loved my Swift II but it seems for me that it just isn't going to work right.

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