Complex/Central Apneas

[bloggins]

I have been to my Sleep Specialist and I am going to have another sleep study that focusses on Complex/Central Apneas. The Dr. believes from the present info that he has is that I may have Complex SA. This of course will involve new technology as far as the therapy goes. I have been reading extensively about my options. The first being the Resmed Vpap Adapt SV machine and the other being the Respironics Bipap AutoSV. Does anyone have personal preference as to which machine has been most successful?? I have tried CPAP machine from Resmed (S8 Avantage) and a Bi-Level Machine from Respironics and I seem to believe that the Resmed machine exhibits more quality, however, I realize that it's whats inside that matters most.

Not sure when my sleep study will take place thus I certainly wouldn't purchase anything prior to receiving and discussing my results with my Dr.

The second question that I have is in one article the Weinmann Machine (SOMNOvent CR) is being discussed and it speaks to the fact that the Resmed SV tracks volume and rate, as opposed to the Respironics BiPAP-Auto SV tracking peak flow and rate. I'm not sure of the diffence between peak flow and volume and what each stands for and the importance of same??? Also, maybe someone could shed some light on which are the two more important areas to monitor. I know that Respironics speaks also to the fact that all their tracking is done digitally and thus more accurate in its calculations. Has anyone noticed a difference in the monitoring factors between your two machines????

Thank you in advance for the assistance!

Repironics Bi-level machine on trial with humidifier

Swift LT mask

[mountainlvr]

I will be interested in following your progress. Please update after you've had your study. Central apneas confuse me and I've been told I have them.

Thanks for posting and good luck!

[bloggins]

I will be very interested in your progress as well. With my limited experience with my situation but my extensive research of Complex/Central/mixed apneas along with periodic breathing, I believe that the M Series Auto CPAP Machine with C-Flex does not address these issues - particularly Central Apneas. They need less pressure to subside not more which I believe the above machine delivers in these situations. Will keep this chatline posted as I work through this problems.

M Series Auto CPAP Machine with A-Flex

Swift LT mask

[dsm]

A good topic for a thread & I will be very happy to participate - just need to tidy up a few issues elsewhere & will then join in

Cheers

DSM

[Kiralynx]

I'll be interested in the discussion as well. I have complex apnea, and a Respironics Bipap Auto SV.

The Respironics machine is the only one with which I have experience. In the beginning, when my Epap was too high, I was having what I believe were centrals. Now that we seem to have gotten that adjusted, I typically have an AHI of 1.0, all hypopneas. (Of course, sometimes I have 2 strikes, and sometimes 10, and Encore Viewer registers either as 1.0, so my actual average may be lower.)

[dsm]

(got your PM, will post responses here)

Tracking Peak Flow vs Volume (rate being a given and common between SV brands)

Resmed
By tracking volume the Resmed machine is monitoring each breath - this is called the tidal flow or Vt. It samples the breathing cycle (my understanding is it uses the proximal mask pressure sensing line to do this) at many points in the breathing cycle and uses a 3 minute window to create an averaged target of what the volume should be. If during a single breath, the volume starts to fall below 90% of the averaged volume, the machine will *immediately* raise the inspiration pressure to lift the volume being breathed so as to reach the 90% target. The 'proximal mask pressure sensing line' is a feature on the Resmed that is not on the Respironics Bipap Auto SV (I suspect the Weinmann also doesn't use a proximal pressure sensing line). This feature allows the machine to get a very accurate picture of the pressure in the mask at any time whereas other machines estimate what the mask pressure is. The proximal line runs up alongside the airhose & ends at the mask - it can tell the *exact* pressure in the mask at any sampling period. It aids in more accurate control and also in detecting leaks. Also the pressure being delivered to the sleeper is very clearly understood by the machine as it samples it.

Respironics
By tracking Av Peak Flow, the Respironics doesn't need to sample the tidal volume in the way the Resmed machine does. Respironics use a 4 min window in which it monitors the AVERAGE PEAK FLOW and in tracking this it uses algorithmic calculations halfway through the breathing in cycle, to decide if the current breath will meet the 90% AV Peak Flow target. The tracking algorithm for this is part of what they call Digital Auto Track.

Comparison
The Respironics algorithm tends to be softer and less 'commanding' because it is less precise and that actually works better for some people. The Resmed algorithm sort of takes control & you follow it rather than it follow you (which is more how the Respironics SV machine works). Also the Respironics machine is far more leak tolerant than the Resmed machine. But, I have found that can be a mixed blessing. The Resmed forces you to sort the leaks out but when using the REspironics machine I have had what I thought were good nights with it only to look at the data & see a big black bar right across the leak chart & then to feel sleepy in the day.

I would say that the Resmed machine is the better for people who have a very high need for respiratory control (a la Cheynes Stokes) whereas the Respironics is probably going to be better for people with less of that need.

I am tending to use the Vpap Auto SV as my primary machine as I seem to average better days with it but I like using the Bipap Auto SV as it is less commanding.


Centrals vs Irregular or Periodic Breathing.
Centrals are dealt with in a very specific manner that is common to all Bilevel S/T and SV machines. That is, the machines all adopt a similar approach which is to cycle between two pressures (Ipap & epap) at a set rate (either preset by the clinician or auto calculated by the rate tracking mechanism in the machine - but, auto rate calculation tends only to be implemented in SV machines from what I have seen).

The gap between Ipap & Epap plays an important role in getting the Central dealt with. When the machine detects a zero-flow condition (and depending on brand the machine may have a way of deciding if this no-flow is an obstruction or a pure central) the machine starts cycling between Ipap & Epap at the backup rate until flow is detected then it reverts to its normal monitoring algorithm (which wil of course depend on the type of machine (ST or SV) and the brand).


There is something though that needs to be understood in regard to SV machines and that is how they can tell the difference between a central and an obstruction. The thread on the Weinmann SOMNOvent CR, was highlighting that Weinmann claim their machine can clearly differentiate between them.
The Resmed & Respironics SV machines are not quite as clever in that they rely on the clinician to set EPAP (EpapMin) high enough to clear obstructions then titrate Ipap to deal with Centrals/Mixed/Complex/PB. So when one of these machines sees a no-flow, it sees it as a Central even though it might be an obstruction (as per my understanding), these two machines assume that any no-flow is a central because there should be no 'no-flow' obstructions occurring based on the epap titration. This ability to differentiate a no-flow as obstructive or central is one area these machines can be improved on vs the SOMNOvent CR. In balance though, it doesn't appear to be a big issue unless the prescribing RT gets epap quite wrong & sets it far too low.


DSM

[Sandy9265]

I would be interested too. I was just told I have central and osa last week. Just curious what they may do!

[kebsa]

I have jsut been through this myself after being dx with complex sleep apnea- the first machine i was sent home with was the respironics bipap auto sv and while i felt better with it than without it my AHI was 94, we tried altering the Ipap and epap a few times but the AHI ranged from 94 to 104. I was actaully starting to wonder if the figures were right as i did feel a bit better with the machine that without but still not great. leaks were not an issue so at least we had gotten the mask and chin strap right anyway.

i was swapped to the Resmed vpap adapt SV and the first nights results were an AI of 0 and an AHI of 0.4! and now about 4 weeks down the track those numbers have stayed pretty much the same! I don't think it is a case of one machine being better than the other- from talking to the DME they have found that some people do better with one machine and other will be better with the opposite- i was a bit sceptical as i know that the machines are aimed at dealing with the same problem but i met 2 guys in the waiting room who had been going through the same prolems only they had started with the opposite machine and were now getting good results with the one i had such a high AHI with

from a users point of view, they do actually feel quite different- it is hard to explain but i guarantee i could ID the machine based on how the airflow feels- I have become very interested in this as it seems strange that if some of use did well with one and not the other despite all having complex sleep apnea- it is very apparent from a inexperienced lay persons point of view that these 2 algorithms are very different. I have wondered if the reason for the centrals and complex apnea may make a difference- my problem is due to the degenerative neurological condition MS, rather than sleep apnea being the primary dx.

it wil be interesting to see what others find but my suggestion is flip a coin and then if you don't get good results with the first choice swap to the other! i do feel that the resmed machine feels more natural but i would imagine those 2 guys would say the other machine felt more natural. They are both very good machines with proven records- it would be interesting to see how the Weinmann machine compares as it sounds like they have gone for yet another approach! If it is possible for a froup of complex sleep apnea patients to respond so differently to the different machines it actually makes me wonder if complex sleep apnea is a catch all for more than one form of sleep apnea involving central- a bit like the fact they used to think MS was one disease when they now know there are at least 4 sub typrs and it is suspected that there are actually more than that.. just a thought!

good luck with which ever one you try, it will be interesting to see how you go!