Minimum Auto Range for A-Flex

[Metal-Fatigue]

Hello all!

I've been a long time lurker on the forum, for about a year now, and finally have something useful to contribute after having learned soooo much from everyone here.

I've been using a M-series Auto with C-Flex for about 10 months now. It took me a good long while to sort it out and get my therapy close to where I want it. That required a pretty tight range of pressures when set in Auto mode. I finally settled on 8.5 to 10 cm H20, C-Flex set to 1 or 2 (my tirated pressure is 8). This gave me an AHI of about 0.5 to 1.5 with occasional burps to around 2.3 or so. I wanted a spare machine and also have one to keep at my girlfriends house so I could be a little more spontanous with my visits, i.e., not have to plan to pack my rig if I knew I was going to be on her side of town. Anyway, to cut to the chase...I just bought another M-series Auto, but this time with A-Flex. In setting this new A-Flex machine up I tried to enter my established pressure range and give A-Flex a shot. The menu system in the machine has you set the upper pressure then the lower pressure. I set the upper to 10, but could not set the lower pressure to 8.5. The highest it would go was 8 before cycling back to 4 then increasing to 8 again as I pressed the "+" button. Not being able to set the correct range, I decided to give it a try...Ended up with an AHI of 2.3 comprised mostly of hypopnias, i.e., lower pressure was too low. I went back and played with the machine and found that if I increased the upper pressure, it would also let me increase the lower pressure. With the machine set to A-Flex, it would only allow me to set a minimum 2 cm H20 between the upper and lower pressures. In C-Flex I could set my usual 1.5 cm difference.

Go figure...I learned something so I thought I'd pass it along.

Scott

[painterman]

I found out that last week as I was trying to narrow the range on my a-flex. 2 is the minimum as you found out. I was wanting to go even narrower to take advantage of a-flex (which I love) and yet almost be a cpap or straight pressure. To go straight cpap you have to give up a-flex. I was sad to find out that 2 was the closest you could get between the low and the high number.
Jon

[Metal-Fatigue]

It dawned on me that the basis for the 2 cm minimum auto range when the M-series is set to A-flex is based on the 2 cm of pressure relief that A-flex reportedly provides as indicated by Titrator here:

viewtopic.php?t=20772&highlight=aflex


Scott

My oxygen starved brain just took a little bit to put the pieces together!