sleeptech

It is standard and best practice to have a second study to determine the ideal pressure for you (a process called titration). It is a good thing that your doctor is doing things properly rather than skipping steps (which many do).

Are you sure it doesn't already have an SD card? Anyhow, inserting one to get the data downloaded to it will have no effect on whether the data is also transmitted via the mobile network. It will continue to transmit whether you want it to or not. Unless you put in airplane mode of course.

That sentence you quoted means that the machine will not adjust its pressure in response to events until the ramp has finished. It does not mean that they are not detected and reported by the software.

Some people's obstruction becomes much worse when they move from a nasal mask to a full face mask. I have seen this happen a number of times while titrating people. One possible explanation for this is something which is known in sleep tech circles as the "reverse MAS effect". This hypothesises that the full face mask presses on your lower jaw which in turn presses on your airway and thus increases the collapse. Increasing the pressure should correct it, but the question becomes whether the pressure increase makes it too uncomfortable to use. By the way, as far as I am aware changing the mask type only changes the level of intentional leak which the machine expects to see.

I find your last comment interesting and it brings up a good point. There is no correlation between body size and the size of mask required. The mask doesn't fit your whole body, just specific areas on your face. I would have thought almost anyone who deals with CPAP gear would know that. It would appear not. It seems like there are very few places you can go in the US to get an experienced, impartial opinion about a masks or machines. Having said that, there aren't a lot of places you can go in Australia either. I just happen to work at one.

Has anyone investigated narcolepsy? It would the standard procedure with your level of reported sleepiness and nothing being picked up on the initial sleep study.

Also, what you describe suggests that you probably are falling asleep while driving, only for about a second at a time, even if you don't know it. Be cautious.

I am not familiar with this specific software, but I can tell you that most (and probably all) of the machines I have seen data from will detect events while the pressure is ramping. I believe that is what you were asking. It is quite possible that you simply don't have any events in the first 45 minutes of your sleep.

The humidifier chamber, especially the bottom of it, can get quite warm (bordering on hot as you say) during operation. I can't a lot of detail specifically about the AirSense 10 just at the moment because we don't use them very often. Check that your filter is clean. It is behind a small, hinged flap on the left side of your machine as you look at it from the front.

When you stop breathing in sleep, it is classified as either a central apnoea or an obstructive apnoea. Obstructive is by far the more common. It means that the muscles which should hold your airway open are relaxing too much in sleep and allowing your airway to collapse, thus obstructing airflow into your lungs. A CPAP machine fixes this by using positive pressure to inflate your airway and prevent the collapse. A central apnoea is very different from an obstructive one. A central apnoea occurs when the muscles which should be pushing the air in and out of your lungs stop. The difference is important because CPAP is rarely effective in treating central apnoeas. It doesn't matter how much your air way is opened up if your muscles aren't pushing the air in and out. It is still treatable with a very similar machine to a CPAP called a BiPAP (amongst other things).

This is all rather a simplification, but I hope it helps you get a grasp of the concepts.

I have seen what you describe in many of my patients. Probably the best approach to to address the dropping of your jaw by using something like a chin strap. It wouldn't have to be tight, just enough to stop the jaw sag. I know Wiredgeorge has found a boil-and-bite mouth guard very helpful in this department. You could try looking at a Simplus mask, but I suspect you would have the same problem.

It can't hurt to have another study. And it also can't hurt to try CPAP just to see if you feel better. Just because you have an AHI of 4.4 doesn't mean that you don't have OSA sufficient to affect your sleep quality. AHI is only part of the picture. And the fact that you did not get any REM sleep also means that it may well be an underestimate.