(06-07-2014 10:09 AM)jcarerra Wrote: I agree with your discussion of the terminology. In some sense, it doesn't matter, but in another, it is important for there to be common definitions so that correct communication occurs. I think the Auto CPAP is quite accurate and descriptive, but rarely used. The shortened version, APAP, is also accurate though not as clear to people who don't know it yet. CPAP now has become an aberration; if interpreted PURELY, it does not include APAPs (or whatever other variants of these there are...BiPAPs?? whatever that is). But many now are using the term CPAP to include ALL air-delivery machines, while others restrict it to only the historical fixed-level machines. So, it is THAT acronym--CPAP--that is now ill-defined, except to those people who have decided they know EXACTLY what it means!
Well, CPAP = continuous (fixed) pressure machines historically came first. And that's why they're the ones still called CPAP and nothing else but CPAP.
An interesting acronym that is growing both on forums like this and in the medical literature is xPAP where the "x" is a variable that stands for one of:
C (fixed continuous positive air pressure)
A (auto adjusting continuous positive air pressure)
Bi or V (fixed bi-level continuous positive air pressure; there's one fixed pressure for inhale and a different fixed pressure for exhale)
Auto Bi or Auto V (automatically adjusting bi-level continuous air pressure; the inhalation and exhalation pressures are allowed to vary, but they're still set separately from each other)
ASV (auto-servo ventilation continuous positive air pressure; these machines can act like non-invasive ventilators and actually trigger inhalations when a person is failing to breathe on their own. They are mainly used to treat problems with central sleep apnea, where the problem is that the brain "forgets" to breathe rather than the airway is collapsed.)
But the context is also important: CPAP and xPAP are used interchangeably in some conversations (i.e. CPAP stands for any kind of PAP) and CPAP means "fixed continuous positive air pressure" in other contexts. When talking prescriptions, CPAP means "fixed continuous positive air pressure" and nothing else. If a doc wants something else, the something else must be explicitly specified.
Quote:To my situation...
last night, I turned off the EPR? (acronym deficiency again) --the thing that reduced pressure on exhale. AND, I upped the pressure from 12 to 14.
EPR = Exhalation Pressure Relief. The idea behind EPR is to make it easier for a person to exhale against the continuous positive air pressure by reducing the amount of continuous positive air pressure being delivered.
EPR is a patient comfort setting. If you don't like it, turn it off.
Quote:My thinking on the EPR is that, even though I had it set to 'fast,' that pressure did not return to high level until the machine detected start of an inhale.
That is indeed how the Resmed EPR system is designed to work. It's often referred to as a "poor man's BiPAP around here because essentially when EPR is turned on, the S9 machines are using one pressure for inhalation (the pressure setting) and another pressure for exhalation (the pressure setting minus the EPR setting).
So if the pressure is set to 12 and EPR = 3, then:
- Pressure on inhalation = 12
- Pressure on exhalation = 9 = 12-3
And the machine starts to increase the pressure back up towards 12 near the end of the exhalation and then bumps it all the way up to 12 by the peak of the inhalation.
Quote: But if you were 'apnea-ing' (especially a central), that signal would not even exist--and you would not get the pressure rise. I am thus running a machine essentially identical to those of decades ago, except that it collects data.
All those years ago EPR did not yet exist. The old CPAP machines delivered the same pressure regardless of what was happening. If the pressure was set to 12, then the pressure was 12 when you were inhaling and it was 12 when you were exhaling and it was 12 when you were breathing fine on your own and it was 12 when you were having apnea after apnea after apnea.
Thing is, there's nothing a priori
wrong with plain old CPAP = fixed continuous positive air pressure if the pressure is sufficiently high to keep the airway open all night long
Quote:RESULT: AHI of 0.6--much better. I have not looked at the details yet.
What you are going to notice when you do look at the details is this:
The pressure will be at 14 all night long after the ramp period is over. It will be at 14 when you are breathing normally (almost the entire night). It will be at 14 during the random apnea/hypopnea events. It will be at 14 right after those events are over. And since you turned EPR = OFF, if you look at the pressure data stats in SleepyHead, both the Pressure and EPAP Pressure stats will be the same. And if you look at the Mask Pressure graph in Sleepy Head, it will be a fuzzy line right at 14 cm all night long.
The AHI is dramatically better simply because 14 cm of continuous positive air pressure is enough to keep your airway from collapsing and 12 cm of continuous positive air pressure on inhalation and 9 cm of continuous positive air pressure on exhalation is NOT enough to keep your airway from collapsing
Because you changed both the EPR and the pressure setting at the same time, we don't really know if the problem with pressure = 12 and EPR = 3 was the exhalation pressure of 9 cm was too low or the inhalation pressure of 12 cm was too low or both were too low.
Quote:I have a question: what is the contraindication for using pressures higher than "needed?" In other words, if 12 would mostly solve your issues, what would be the problem (danger?) of running at 14? <<<Should this be a separate topic for the forum?
Short answer: In you can tolerate 14 cm in terms of comfort and you don't develop problems with pressure induced centrals, there is nothing wrong with using 14 cm instead of the titrated 12 cm.
Longer answer: Since last night went much better, you have evidence that your titration study may have resulted in an under titration
: In other words, the night of the titration was not representative of what really goes on in your bed each night and you actually need a bit more pressure than 12 cm on a regular basis. Titration studies are NOT perfect, they really only provide a good starting "guess" as to what the real pressure needs are. Some people wind up being under titrated and some folks (like me) wind up being over titrated.
And the chances of developing pressure induced centrals is NOT very high; only about 10% of new PAPers ever have problems with pressure induced centrals, and for many of those PAPers, the problem will go away on its own once their body acclimates to xPAP therapy.
Hence, as long as your data continues to look good at 14 cm of pressure and you feel better (long term), then there's no good reason to NOT use 14 cm.
So I'd suggest that you leave the settings where they are for the next 4-7 days and then look at all
the data as a whole. What I mean by that is to look at all the detailed data as a whole data set made up of 4-7 individual nights as well as the summary data from the entire period. Our OSA is not the same from night to night, and we all have the occasional really great nights and the occasional pretty bad (for us) nights. You don't want to get into the habit of increasing the pressure every time you have a bad night. But if you a week of bad nights, then you know that the current pressure may not be enough to manage the OSA.