Please help me understand (CPAP vs. Auto-CPAP)

[Ulrika]

thank you for all of the replies...very helpful, babydoc I think you are right, I will look at going ahead with the elite as I can get it almost free with my health insurance and if I need to use an auto I will just rent the auto for a couple of months. It is so good to have some opinions and different suggestions - even though where I got my machine from are helpful, I want to know that I have done my "homework" as well afterall the people who use the cpap equipment are the best source of information.

[zonk]

thank you for all of the replies...very helpful, babydoc I think you are right, I will look at going ahead with the elite as I can get it almost free with my health insurance and if I need to use an auto I will just rent the auto for a couple of months.

It seem prices in Tasmania much cheaper than mainland. $1000 is good deal in Aus, The best price could find for S9 Elite/H5 humidifier $1300 from cpapexpressaustralia. Make sure its not the S9 Escape or used machine. It should say Elite next to stop/start button and does no harm to check the hours on the machine (hours cannot be erased) before you take the machine home ...Let the buyer beware

[Ulrika]

Thanks for the advice.... my supplier said the elite is on special atm - it's not normally below $1000. I will definitely check that it is new and also no an escape.

[zonk]

You can choose the extended 5 years warranty on the machine (humidifier not included) for extra $99.
Speak to your supplier if interested
http://www.sleepvantage.com.au/sleepvant...ranty.html

[marcellocarvalho]

I'd keep the Autoset. APAPs are like little sleep studies.

Have you tried narrowing the Autoset's range? Meaning, if you do well at a pressure of 15, you could do a low of 12 and a high of 17.

How high did it go when you used it in auto?

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I do not get it...

“The difference between auto and fixed is that an auto will adjust your pressure to your needs while sleeping. If your needing a higher pressure during the night for some reason an auto will adjust it to compensate where as a fixed will keep at the same pressure all night. “ Dreamcatcher

If an Auto CPAP will adjust the right pressure throughout the night, why some one will/need to change the pressure in it
from
04 to 20
to
12 to 15?

If we keep the pressure 04 to 20 won’t the machine adjust to whatever is best at each moment?

I have my ACPAP pressure set as
04 to 20 (default)

My pressure data is

Average Pressure - 95% Pressure
----------------------------------------------
Most recent…….5.5 - 9.5
Last 7 days……..4.8 - 8.0
Last 30 days…..4.8 - 7.0
Last 6 months…05.2 - 8.0

Is there any need/benefit to change the current pressure (04 – 20)?

Thanks for your help

[PaulaO2]

The main problem with keeping a machine wide open like that is simple.

Let's say I'm driving down the highway. The speed limit is 55. I'm doing 55. There is a hill and the big truck in front of me is going to have to slow down so I pass. Passing him is easy enough because I'm already going fairly fast so me climbing the hill is no issue. It is efficient.

Let's say instead that I am going less than 55 and I come across that slower truck. In order for me to climb the hill and go around him, I have to apply even more gas or I will be going as slow as he is or perhaps slower. It is not efficient. Yes, I'll still make it to the top of the hill, yes, I will still make it to work, but it is not efficient. I lost time. And gas.

Let's say that your ideal pressure to prevent an event is at 12. Your machine is set to wide open (4-20). When you fall asleep, the pressure starts to climb, trying to find that "sweet spot" necessary to keep your throat open the most efficiently. While it is trying to find that, your throat is closing. The machine has to work harder, rising the pressure higher and higher until it gets to where it needs to be to prevent the event. Sometimes it cannot rise fast enough and an event happens anyway. Sometimes it rises so fast, you wake up. The pressure goes back down. And it starts all over again.

But, if you have the gap narrowed down, based on your data you've gathered, you set the machine to perhaps 10 and 16. Now when an event happens, the machine can react faster. And easier. You don't wake up to the pressure changes, not like you would have otherwise.

These machines are smart but they aren't that good. They can't remember "Oh, Paula is falling asleep and I know I need to be at least 10 to keep her throat open so I'll just jump to there and wait until more is needed." But by narrowing down that gap, it doesn't have to do much to keep doing it's job. There is not time wasted trying to figure it out each and every night.

[Zorki1c]

I'm fortunate, I guess. I'm on Medicare and am running a fixed pressure with good results. My first machine was an F&P ICON (the doctor specified the ICON) and the DME automatically provided the Auto+ model. After a few weeks I talked the doctor into letting me switch to the ResMed S9 and the DME automatically provided the Autoset. No cost-cutting on its part.

[marcellocarvalho]

The main problem with keeping a machine wide open like that is simple.
Let's say I'm driving down the highway. The speed limit is 55. I'm doing 55. There is ....

OK, it does makes sense. Thanks.

[RonWessels]

PaulaO2 does a good job of explaining one of the issues with wide open settings. But it's not the whole story.

There are actually three parts to your question. The first is why would you keep the lower limit at 4 rather than raising it up. PaulaO2 explains this quite well. One other point that was not mentioned is a peculiar effect: when you are used to a higher pressure, a lower pressure feels like there's "not enough air" and you become uncomfortable until the pressure is raised. Most people that become accustomed to their pressure completely stop using the ramp feature on their machines. [ That same ramp feature is invaluable when you are first getting used to the treatment. ]

One reason why you might (temporarily) want to keep your lower limit below the minimum you need for apnea suppression is that it will act like a "sleep-dependent" ramp feature. The actual ramp feature on machines will linearly increase the treatment pressure on a fixed-time basis. This has the disadvantage that, if you take a while to get to sleep, the ramp might finish before you fall asleep, forcing you to fumble for that ramp button to restart it. However, until you actually fall asleep, you won't experience any apnea events, so the auto algorithm will keep the pressure at its lower limit. Then, when you fall asleep, the auto algorithm will increase the pressure appropriate for treatment.

The second part to your question is why you would keep the upper limit at 20 rather than lowering it. And the third (implicit) question is why would you have settings that are below what might be required to eliminate apnea events.

The answer to these last two questions is straightforward: compliance. By far and away the greatest cause of CPAP treatment failure is because the patient stops using it. Now, if you have been newly diagnosed and have a "high" pressure setting (say 17 cmH2O), you have a huge hurdle to overcome. Not only are you going to have to find a comfortable mask (which is a task in itself), but you are going to have to cinch it down quite tightly to stop it from blowing completely off your face. Plus, you have what feel like gale force winds blowing air at you. Not very relaxing. You have a real uphill battle that a lot of people simply give up on.

Now imagine a more gradual response. Forget trying to solve the apneas all at once. Start off with a lower pressure, say 8 cmH2O, and get used to that. Get used to a mask on your face. [ This is actually a huge hurdle for some. ] Get used to exhaling against pressure (yes, you do get used to it). Then, as you become less uncomfortable with that (I would say "more comfortable", but let's keep it real here), increase the pressure. Eventually, you're at your ideal pressure and you can actually fall asleep and stay asleep without too much trouble.

That is why you might want to keep your upper pressure limit less than the wide open setting of 20 cmH2O.

Having said that, once you get used to the higher pressures, if you don't trust your machine's auto algorithm, you might want to put in a fail-safe upper limit on the pressure. If you do trust your machine's auto algorithm, I see no reason why you would not increase it up to the wide-open setting. Either you need that higher pressure (in which case why not provide it), or you don't (and the machine would not provide it).

Hopefully this answers your question.

Now, looking at your specific case, your average pressure values are down at the 4.8 - 5.5 values. There is no point in providing a pressure higher than what is required to prevent your apneas, and 4.8 - 5.5 cmH2O does prevent your apneas at times. Hence, I would not increase your lower limit of 4, or at worst only increase it to 5. That is actually frequently sufficient for you. As to whether to decrease the upper limit, you have actually proven that your machine does not "run away" with too high a pressure, so I would not bother. As time goes on, perhaps the pressure you require will slowly increase (it happens as we age), and this will automatically compensate.

[archangle]

Why not use auto wide open all the time?

Assume that you need 12 cmH2O pressure, but your machine is set at 4-20.

1) You have to have some breathing problems before the machine adjusts upwards. You have to suffer through some bad breathing before it adjusts upwards. It may make it difficult to fall asleep.

2) The machines don't instantly adjust pressure upwards. If you fall asleep at a 4 cmH2O, and need 12 cmH2O, it might take 8 minutes or so for the machine to adjust upwards.

3) Once you get used to the 12 cmH2O, you may feel like you're suffocating at 4 cmH2O. It doesn't "make sense," but many people experience this.

4) Every time you turn the machine off and back on, it starts back at 4. Once a night, and every time you get up to use the bathroom.

5) Some people only have apneas when they're in certain sleep stages such as REM, or when they roll over onto their back. When you're in the "non-apnea" condition, or if you wake up and lie there before you go back to sleep, your pressure will drop back down. Once you get back into "apnea" sleep stage, you'll be receiving inadequate pressure for a while. This might even keep you from achieving certain sleep stages because it will disturb you.

6) If you put on your mask at 4 cm, it may leak when it adjusts up to 12 cmH2O.

7) I find I feel better if my minimum pressure is a little above what the machine wants to adjust me to. I assume that my breathing is somewhat disturbed in some fashion at, for instance 12, but it's not bad enough to make the machine adjust upwards. I feel bad at 12. If I set it to 16, I feel much better in the morning.