Confused about the APAP versus CPAP and BIPAP

[painterman]

[quote="dsm"][quote="vdol52"]When I bought my CPAP auto with CFLEX about two years ago I was told that it was the best machine available. Now I'm wondering if I should have gotten a BIPAP or APAP.
Is there a website that tells the difference in these machines.
Would I have to have another sleep study? I don't really have a DME because I paid for the machine myself. I used my prescription from way back to get it.
I guess I'm kind of wingin' it.

[Wulfman...]

It is one of the industry's ironies that so many people are talked into buying Autos and take them home set to 4-20 low high. This is plain stupidity.

I still don't understand it. With the auto, it seems that the machine will only go as high as it needs to go. So for the high number, what does it matter how high it is set? Bottom number I can see that being kept to a good number. My doctor had me lower my high number from 20 to 14. I don't think he/they could explain to me why it mattered. Can anyone?

My philosophy:
If you're going to run your Auto as an "auto" (as opposed to finding your best single pressure), then you need to move your bottom pressure up to where it takes care of MOST of your events and doesn't have so far to go to take care of some others.....although some of those other events will possibly/probably occur before it can move up high enough to take care of them.
It depends on what kind of "events" cause your pressure to rise. Autos will also increase on snoring.....most of which MAY NOT preceed hypopneas or apneas. If it detects that you're snoring and it's only due to nasal congestion or something similar, then the machine will keep climbing regardless of other events. This may lead to some disturbed sleep due to the pressure changes. SO.....I tend to believe in a very narrow pressure range in Auto mode.
SOME people also are subject to Central apneas (which should be noted on their sleep studies) and if "pressure-induced Centrals" occur, their therapy will suffer greatly because these machines can't tell the difference between an obstructive and a central apnea. They're SUPPOSED to limit their responses to apneas, but if there is snoring AND leakage going on, then all bets are off.


Den

[dsm]

<snip>


The only problem with what you said is that A-flex only works in Auto mode not cpap mode. I love a-flex, enough reason to run the auto very tight, mine is from 12-14 cm.
Jon

_________________

Jon,

Yes you are right - was not thinking as I typed that line. A-Flex is only on Autos.

Could it work on CPAPS ?, I believe it might as it is essentially a software (algorithm) mechanism although on further thought, the CPAP would likely have to be a model that is fitted with flow sensors as well as the exit pressure transducer. The exhale part of A-Flex doesn't require flow sensor input but the inhale part of A-Flex almost certainly does.

So on further reflection it is the flow sensors that tend to really differentiate an Auto from a vanilla CPAP so I guess A-Flex really is a feature that will only work on Autos

PS The flow sensors are basically identical a pressure transducer but they come in pairs (2 on one chip or assembly) they sample the pressure either side of a 'flow limiting device' placed in the air flow tube just ahead of the pressure transducer (which in turn is right at the air exit point from the machine). The pressure transducer monitors the pressure delivered from the machine, the flow sensors sample the pressure either side of the flow limiting device & can thus be used to calculate how much air is flowing.

The below pics show each of the items mentioned above ...

The very 1st pic shows the flow sensors at the top middle & the pressure transducer to the top right - the flow sensors are connected by air tubes to the plastic 'flow limiting device' & you can see the pressure transducer connected to a sampling nipple just before the air exit point.

http://www.internetage.com/cpapinfo/remstar-auto-dis-1

DSM

[dsm]

It is one of the industry's ironies that so many people are talked into buying Autos and take them home set to 4-20 low high. This is plain stupidity.

I still don't understand it. With the auto, it seems that the machine will only go as high as it needs to go. So for the high number, what does it matter how high it is set? Bottom number I can see that being kept to a good number. My doctor had me lower my high number from 20 to 14. I don't think he/they could explain to me why it mattered. Can anyone?

My philosophy:
If you're going to run your Auto as an "auto" (as opposed to finding your best single pressure), then you need to move your bottom pressure up to where it takes care of MOST of your events and doesn't have so far to go to take care of some others.....although some of those other events will possibly/probably occur before it can move up high enough to take care of them.
It depends on what kind of "events" cause your pressure to rise. Autos will also increase on snoring.....most of which MAY NOT preceed hypopneas or apneas. If it detects that you're snoring and it's only due to nasal congestion or something similar, then the machine will keep climbing regardless of other events. This may lead to some disturbed sleep due to the pressure changes. SO.....I tend to believe in a very narrow pressure range in Auto mode.
SOME people also are subject to Central apneas (which should be noted on their sleep studies) and if "pressure-induced Centrals" occur, their therapy will suffer greatly because these machines can't tell the difference between an obstructive and a central apnea. They're SUPPOSED to limit their responses to apneas, but if there is snoring AND leakage going on, then all bets are off.


Den

[elliejose]

When I was on auto it was set 12-20. The early part of the night always went fine. But between 1:30 and 3:00 a.m. my pressure always went up to 20 and remained there until I got up. This part of the night was when I was plagued by aerophagia and could not sleep because of it and the struggle to exhale. The md first switched me to straight bipap- set 20/15. So the early part of the night I could not sleep because of the high pressure. So I would start the night out with my auto - when I woke because of the high pressure, I would switch to the bipap for the remainder of the night. Needless to say, I still wasn't getting much rest. So for me the auto bipap, has been wonderful - once I got the classic "tank" instead of the M. My M changed tones on inhale and exhale - sounded just like when my mom was on the respirator - so I hated the sound. I would wake up and panic because I had fallen asleep. Also, if I slept more than 5 hours, the humidifier would run out of water leaving me and my sinuses in a terrible state. Here again, the M works very well for some individuals. I told the DME that I was not happy with the M so he switched it for a "tank." So, in short, as the others have said, individual conditions determine what machine is best for you.