(05-08-2013 02:13 AM)vsheline Wrote: Just to be sure the PS [Pressure Support] is not maxing out and needs to be allowed to go higher, I suggest you set the Max PS to your doctor's prescribed setting of 15, rather than the 10 you have been using. If you set the Max PS to 15, the PS won't necessarily ever go as high as 15, since it will not go higher than is needed.
(05-08-2013 07:50 AM)racprops Wrote: As I understand it, I need a ASV partly so that the pressure is relaxed to clear my Centrals and pressure enough for and when I have OAs, and intelligent enough to tell the different.
I was under the impression the machine would not ram high pressure down my air pipe (pun intended) but lightly feed air though my clear airway to insure breathing.
No, Rich, neither the ResMed ASV nor the PRS1 ASV algorithms relax pressure to clear centrals.
It usually takes time to get into a central event, with CO2 levels in the blood gradually becoming too low, until there is a loss of urge to breathe. During the time that our CO2 levels are gradually building up again because we are not breathing, the O2 levels are plummeting.
If the pressure were to be relaxed during a central apnea the central apnea would merely run its normal (long) course.
Once a central apnea begins, the only way to keep us ventilated is for the ASV machine to immediately step in to ventilate us. In order to avoid hyperventilating us, it targets only 90% or 95% of the amount of ventilation which we were maintaining on our own before the central apnea started. Yes, every time we are forced to inhale during what otherwise would have become a central apnea, it is sorta like "ram high pressure down my air pipe", although it is not at all painful and we gradually get used to the feeling.
(05-08-2013 07:50 AM)racprops Wrote: It kind seems counterattacking the problem.....My centrals are caused by CPAP like pressure so pushing a high pressure should make them worst...
The pressure does not directly cause the central apnea; according to what I've read, in some people breathing against pressure somehow causes enough gradual loss or washing out of the CO2 levels in the blood that they lose the urge to breathe. Our nervous system doesn't breathe because it senses that our O2 levels are too low (apparently it isn't able to do that), but because it senses that our CO2 levels are too high.
(05-08-2013 07:50 AM)racprops Wrote: But I kind of see how once I am in a central, IE NOT taking a breath, then it need to VENTILATE me and push in the air..so then Higher pressure might be needed to get the air in.
(05-08-2013 07:50 AM)racprops Wrote: So my thinking is the base pressure, the EPAP 10cm used to clear my OAs might be triggering the centrals I then NEED higher pressure to ventilate me with.
It almost seems a catch 22.
I will try your suggestion, but kind think it will go the wrong way.
Your most recent chart seems to show the PS (Pressure Support, the difference between EPAP and IPAP) still never gets higher than about 10, even when you are having central apneas which the machine seems unable to treat adequately (since it reports CA events are still occurring).
Have you postponed making the change of raising the max Pressure Support setting to 15 as per your doctor's original prescription?
By the way, perhaps your machine is managing to treat your centrals better than we have been thinking, because your latest Oximeter chart shows your oxygen levels were pretty good all throughout the period that the machine was reporting CA events. Except, for less than 10 seconds the SpO2 reading did drop from over 90% all the way down to 80% and then returned back up above 90%, but I suspect that was a false reading, maybe caused by movement of the sensor, because I think there is no way your blood oxygen level could drop that far and return to above 90%, all in less than 10 seconds. (We know the drop lasted less than 10 seconds because it was not listed as an event. SpO2 drops must last at least 10 seconds or they do not qualify as being an "event".)
(05-12-2013 07:47 AM)racprops Wrote: OK I am hoping I can get some help here.
The read outs are looking to my eyes as great BUT are they normal, after all the mask pressure just about disappears, drops off….everything else looks pretty good but for the tidal volume which looks low?
IS this what I want to look for?
The latest chart looks like some of your earlier ones, where your ASV machine is often unable to completely eliminate central apneas, when you have stopped breathing on your own. (You can easily see when you have stopped breathing on your own - it is whenever the machine increases the PS, the difference between EPAP and IPAP.)
Your previous charts also showed you sometimes had few or no central apneas unless you first had obstructive events which caused the machine to need to go to higher EPAP pressure.
What do you think caused the lack of obstructive events in the last, long session? Was your head more elevated than it had been earlier?