How APAP adjusts for apneas ?

[wasColette]

I was reading the clinicians manual for the Resmed Autoset II which I recently traded out for. I have a question about the following statement in the manual:

"An apnea is defined as a greater than 75% decrease in ventilation. The AutoSet
algorithm scores an apnea if the 2-second moving average ventilation drops
below 25% of the recent time average (time constant 100 seconds) for at least
10 consecutive seconds. Treatment pressure increases based on the duration of
the apnea. The pressure will not rise above 10 cm H2O when an apnea is
detected, to prevent an inappropriate response to central apneas. Initial pressure
increases are rapid, but the rate of increase diminishes as the pressure
approaches 10 cm H2O. "

Does this mean that if you have your APAP set between, let's say, 8-15 cm, and it detects an apnea that it would not increase pressure past 10 cm? Or does it mean it won't increase 10 cm more in pressure?

[Wulfman]

The ResMed Autos use the "A10 algorithm". The name of the algorithm corresponds with the 10 cm. pressure limitation. They will not pursue an apnea above the pressure of 10 cm. UNLESS they are accompanied by snores or flow limitations. In other words, if it's already at the pressure of 10 and detects a "frank" (sudden) apnea, it will not pursue it.
So, if a person needs pressures above the pressure of 10 cm. to treat apneas, the ResMed Auto is not the machine to use (in Auto mode). The person would be as well (or better) off with a straight CPAP machine set to an appropriate pressure to prevent the vast majority of apneas.

If you go up to the Search function and put in "A10", you will find a huge number of threads/posts discussing it. (12 pages worth)


Den

[wasColette]

Wow! That is amazing to find out. I hope a lot of the newbies here know this because the ResMed Auto may not be right for them.

Thankfully for me mine is set 5-10 cm. I wonder if I did have a higher titrated pressure range if the DME would have stirred me toward a different machine. Very interesting.

[grumpygirl]

Wolfman- What Autopap machine would you suggest for those of us who need a machine to respond to apneas above 10cm pressure? I was titrated at 12 and am using the ResMed Auto with my pressure range of 9-13 to avoid horrible aerophagia but these pressures do NOT seem to be giving me effective treatment since I am as tired now as I was before I was even diagnosed. So, what auto machine do you think would be good for me? I would LOVE to approach my DME with some knowledge about this subject.

[ozij]

Grumpygirl,
If you have apneas above 10 without snores or accompanying flow limitation, you may get better treatment from the Respironics, or the Sandman autos. Each has a different way of handling potential central apneas, and either way may be better for your breathing pattern.

O.

[sleepyangler]

My 1st cpap was a resmed apap set at 11 to 15cm based on a PSG titration of 12. Over nearly 5 moths of use the machine never responded to nearly 1/2 the apneas shown on the nightly downloads of my data. I've since purchased a sandman auto which is set at the same 11 to 15cm and my ave nightly AI has dropped from 3 or 4 to consistently less than 1. May not sound like much to some, but the real world difference, meaning how I feel each day, is beyond description! The sandman will allow you to select the pressure at which the machine will not chase an apnea, rather then relying on what the company feels is good enough. Mine is set at 14cm right now and I couldn't be happier. The sandman also has a few other settings that can be tweaked, unlike the resmed. It is a much better machine for me and anyone who's titrated pressure is above 10 would do well to at least look at the sandman before making a final decision.

[Wulfman]

Wolfman- What Autopap machine would you suggest for those of us who need a machine to respond to apneas above 10cm pressure? I was titrated at 12 and am using the ResMed Auto with my pressure range of 9-13 to avoid horrible aerophagia but these pressures do NOT seem to be giving me effective treatment since I am as tired now as I was before I was even diagnosed. So, what auto machine do you think would be good for me? I would LOVE to approach my DME with some knowledge about this subject.

Well, as I said, there are lots and lots of threads/discussions on the forum about the various algorithms and ways that the machines work.
Respironics has their own approach in that if after three attempts at raising pressures, the apnea still appears to be resistant, the machine will drop the pressure below where it started to pursue that event. In this case, the Respironics machines don't necessarily differentiate at a set pressure like 10 cm. (which is the "dividing line" where research has apparently shown where pressure-induced Central Apneas can start to be more prevalent.....IF a person is susceptible to them)
I'm not familiar with the new Sandman/Covidien Auto, but they all have different methods of trying to avoid Central Apneas. The Sandman/Covidien and it's predecessor the Puritan Bennett 420E are also first-rate machines.....however, they don't offer exhale relief.

Have you tried single-pressure (CPAP mode)? Many of us are sensitive to the pressure changes from an Auto when we sleep.
Also, along this same line of thinking, have you tried to determine at what pressure your aerophagia becomes worse?
There have also been many discussions on finding the right combination of pressure(s) and exhale relief needs to avoid aerophagia. Some have luck with straight pressure (with and without C-Flex/EPR). Some succeed with APAPs. Some need Bi-PAPs.......etc., etc., etc. It's very individualistic.


Den