Is my auto cpap machine stupid?

[remstarcpap]

Just checked the last week of data for my Respironics M Series Auto, posted below. Is my machine stupid? It seems to spend a lot of time at pressures that produce lousy numbers. Why? I always assumed that the purpose of the auto machine was to find the ideal pressure to reduce events. My range was set at 7cm to 14cm. It seems like the best pressure is 10cm. should I just set a fixed pressure of 10cm?

[JeffH]

IMHO yes, just set it at 10. I too thought an auto would do more than it's designed to do. I can't handle the different amounts of pressure thru the night....they woke me up.

Someone smarter than me chime in and explain how an auto works.

JeffH

[sepool]

I'd like to see the daily graph in addition to the summary you are showing.

It takes any auto time to get up to the needed pressure because it makes tiny changes and tests that for awhile.

You could set it to constant 10, or tighten up on the lower number, say change it to 9, to start it closer.

Sam

[raylo]

It looks like you're spending 74% of your time at pressures that give you an AHI of less than 3. That doesn't sound bad. It looks like you have 1 - 2 apneas per night at the lower pressures (7 and . That is probably just enough for the machine to react. Have you tried 9 as the minimum?

[Goofproof]

The daily graphs tell what's going on, not what you posted, it's just fluff. Jim

[remstarcpap]

Can anyone explain how an auto machine works? What does it sense, and how does the algorithm work. If I have 2 or so apneas per hour, and 4 or so hypopneas, will the machine react? Or is it calibrated only to look for worse sleep apnea? How does it tell if I am snoring?

Would it make sense for me to set the range between 10 and 11, or is that just silly, and setting fixed pressure on 10cm would be simpler and better?

The daily graphs are similar, with the lower pressures showing more (not a lot) apneas and hypopneas.

[Wulfman]

Go to the Respironics site and start reading (link below), or start searching CPAPTALK. It's been explained here numerous times before.

http://sleepapnea.respironics.com/techn ... rithm.aspx


Den

[dsm]

As a simple summary, Autos do this ...

1) They were designed to operate at the lowest pressure allowed (in the settings) in order to help users avoid the typical mask management and other types of problems associated with higher pressures (higher pressures start around 13-15 CMs. At 16 mask leaks can start to become a PITB)

2) Autos look for indicators (snores, hypopneas, flattenting of the insp curve as usually happens in flow limitations) that warn of impending apneas & the Autos try to pre-empt them by raising pressure in advance. But when an event strikes the machines sit it out.

3) Unfortunately Autos also adjust pressure very slowly. This is to avoid creating more problems that they are trying to solve (waking the sleeper, inducing centrals, responding with pressure to the wrong type of apnea (patterns of centrals are not cleared by rasing pressure in advance). If a RT sends someone out the door with the range wide open (min 4 & max 20) then it is quite probable that person will not be getting the best therapy (depending on just what characteristics their apnea has).

The reality with Autos is that we expected a lot more from them than they were ever capable of. In the start we tended to tout them as the ultimate answer - "the auto will hunt down your apnea & zap it" - that was an extraordinarily naive view we held & was promoted back in 2005/2006, until the reality settled in plus some of us began examining the patents in great detail plus did tests on various types of Autos.

Bilevel Autos are now flavour of the era & most folk can get what they want with one but there are a few more variables to grapple with.

DSM

[elader]

restrict the range to 9-12 and leave it for a week, then decide on a fixed pressure and set it on a range like 11-11 so you keep all the recording features active.

[remstarcpap]

thanks Den, for the Respironics link. Still curious how the magic works, but that's for later. I guess I had the misconception of the "magic auto" that senses my apnea, and instantly adjusts! Now I know better, and will experiment with some fixed pressures and small ranges.

[Wulfman]

thanks Den, for the Respironics link. Still curious how the magic works, but that's for later. I guess I had the misconception of the "magic auto" that senses my apnea, and instantly adjusts! Now I know better, and will experiment with some fixed pressures and small ranges.

It's a combination of airflow, sensors and the algorithmic program. It interprets some condition (or event) with the sensors and the program responds based on that information. Simplistically put, like a computer program, it says "If this condition/event is detected, then do this (some response), otherwise do something else (or nothing)" It doesn't know what pressure will stop an event until it moves the pressure up and waits for results. It won't immediately go from 8 to 12 or 15 because it has to gradually move in that direction and try to determine if the event still exists after a previous pressure increase.
On the other hand, leaks and snores will trigger faster pressure increases than hypopneas or apneas. If the user has problems with leakage, it can result in very disturbed sleep.

It's not "magic". However, knowing how they work and their strengths and weaknesses is a step in the right direction to successful usage of them. AND......having the software to interpret the results is an absolute MUST, in my opinion.


Den

[roster]

The daily graphs tell what's going on, not what you posted, it's just fluff. Jim

Ditto.

Remmie,

If you want to adjust your pressure, the daily graph should be closely interpreted and used to make the changes. You should also understand Positional Sleep Apnea and the effect it may have on pressure requirements (viewtopic/t40307/viewtopic.php?f=1&t=40 ... 94#p352594).

Regards,

[Goofproof]

If it were "M"agic, we would probably find Fairy Dust on the nightstand, and maybe so Rabbit droppings too. Jim