Why Does Reqd. Pressure Vary So Much from Night to Night ?

[mymontreal]

Hi

I have been on Auto CPAP for about 12 months now and have been monitoring my progress with the use of EncorePro software.

(You may have noticed in another post that I am currently suffering from bloating issues & at my Doctor's suggestion, I am going to try an Auto BiLevel shortly, to see if that improves the situation).

I am trying to figure out why the average/90% pressure varies so much from night to night (glad I at leasy have an auto machine...) - I mentioned it to my Doctor and he said it is normal, as it depends on alcohol use and sleeping position - however, I rarely drink alcohol and always sleep in the same position, so I am surprised that it varies so much...

On nights when the 90% pressure is 15, you can see it's actually maxing out at 15 - it would probably go to 16 or 17 if apap max wasn't set to 15...



Yet on many other nights, my 90% pressure is 12 & the machine doesn't even try to go above 12 to resolve additional apnea events.



In all cases, it's difficult to get my AHI value below 5 (maybe due to bloating issues ?), yet my leak from Swift LT seems to be under control.

Anybody have any thoughts ?

Thanks
Mike

[Pugsy]

I have nights with graphs very similar to yours except my max is 20 cm and I have seen 18 fairly often. I have varied my minimum from 9 to 12 to see if it made any marked difference but it has not. Like you, can't blame it on leaks. Like you, sometimes I get events showing and the machine sits by twiddling its thumbs... Then sometimes I get an AHI of less than 1 and the machine never does more than its usual little probe upwards testing things.

It might be that some events are just more stubborn if I am on my back. I haven't figured out any direct correlation and there doesn't seem to be any trend that I can see. It is just a random thing, for me anyway.

Sorry, I am no help but sometimes it helps to know you aren't alone.

I don't have any aerophagia problems, so I don't mind the maxed pressure. It doesn't bug me.

[Muse-Inc]

It takes a long time for some to heal and there may be other conditions that affect how fast the body-brain heals. The brain is slow to change and it's been keeping you alive by not letting you fully relax in to deep sleep which paradoxically increases events. The amt of pressure delivered is dependent not only on your particular airway anatomy but also on how relaxed-floppy your airways are when you relax into sleep. The CPAP air is acting to stent open those airways and I doubt it's a static thing in the begining or maybe ever.

[Julie]

Have you considered that you might need a full face mask because you could be mouth breathing, at least intermittently, overnight? It happens to so many of us.

[Guest]

Interesting to note that your VSI is zero, yet your graph shows multiple OAs... Could it be that you are using too high a pressure and that the OAs are actually centrals?

[mymontreal]

Have you considered that you might need a full face mask because you could be mouth breathing, at least intermittently, overnight? It happens to so many of us.

Hi Julie

Yes you are right, I should probably consider a full face mask - however, I did try taping my mouth for a few weeks & seemed to get similar results ie. required pressure varying quite a lot from night to night...

I aAm due to pick up an uto BiLevel machine from the DME Today, so I'm keeping my fingers crossed that will help with the bloating.

They originally wanted me to do another sleep-study before getting the BiLevel machine (so that they could see if a fixed BiLevel would be ok), but I am reluctant to pay another $400 out-of-pocket for an additional sleep-study - plus, I feel like the sleep-study is just a "one night snapshot" - if the required pressure varies so much from night-to-night anyway, what's the point...

Mike