(02-18-2014 01:31 AM)Kate Wrote: I don't know why the ASV machine isn't quieter. They say it is but it really isn't.
The ASV is changing the pressure much more often and in greater increments over shorter periods of time if you are using it in ASV mode. (And if you're not using ASV mode, then the question becomes: Why were you switched to such an expensive machine.)
In ASV mode, the machine will quite drastically increase the IPAP pressure over one or more inhalations while leaving the EPAP along when it is not happy with the way you are breathing---it's doing that in an effort to trigger inhalations. That's how this machine treats central apneas---it triggers an inhalation by increasing the difference between IPAP and EPAP when you are not breathing sufficiently well on your own, so on every timed or triggerd inhalation the pressure increases by as much as 10cm above the current EPAP pressure. And that, in turn, helps keep the CO2 overshoot/undershoot cycle from developing. But that 10cm increase in pressure on each inhalation can also be noisier than a plain old APAP.
So some of what you're dealing with is just the nature of the machine you are now using. Face farts are an issue with people using ASV machines simply because the sudden and significant pressure increases make it harder to keep a really sound seal on the mask once the ASV algorithm kicks in and starts triggering inhalations.