Aircurve 10 ST-A and Lumis 150 VPAP ST-A just a UK branding difference?

[StuartC]

Yes, the Lumis will calculate and consider Flow Limitations when Auto EPAP is used, but not when it is off.  That is what I have described for my usage.

iBR should prevent CAs from happening by triggering IPAP to initiate flow within less than 10 seconds.  Added to that, the adjustment of PS to maintain constant volume is somewhat similar to an ASV, so it could eliminate (or just reduce) periodic breathing too.  So it is not that the events are not seen or logged, it is that they did not occur.  I then interpret the Spont. Trigger percentage as being the evidence of the machine taking corrective action - the lower the percentage, the more corrective action.

If you are seeing large numbers of CAs, the VAuto is not actually the right machine for the job.  Obviously, the ASV gets promoted as being specifically for that but you do at least need a mode with timed backup, even if it is only ST, which is also on the Lumis 150.

[SingleH]

Ok all clear on the iBR. Interestingly when I did the testing with the Lumis despite the low figures his Trigger values were good, 97% or so but the cycle was low. He seems to like to take long breaths and needs a Timax of about 2.5 for spont cycle figures to be good. I seemed to recal the Lumis had a max limit of 2.3s for Timax.

Does your Lumis have a limit on Timax?

He gets CA's varying from about 0.5% to 7% Central apneas per night. I dont know "how high" this is in the grand scheme of things, but I do clearly see his central and normal apneas are always clustered together so one seems to be leading to the other.

I did look at the ASV but had focused most of my research on the Lumis given its recommendation for restrictive disorders such as scoliosis and also the fact that ASV didn't have auto-EPAP either.

[StuartC]

I have not checked my machine but the clinical guide says Ti Max on the Lumis has a range of 0.3 to 4.0 s in intervals of 0.1 s.

ASV is quite likely not the right machine for the bigger picture you are dealing with, it is just the machine that is specifically intended for CAs and CSR compared to the others.  It does have Auto EPAP, it is the difference between ASV and AutoASV modes.  One feature of the ASV is that all you really set is EPAP (range in AutoASV) and PS range.  You do not get to set target volume, backup rate, trigger or cycle, rise time or Ti min or max.  It is very much a "black box" magic machine compared to iVAPS mode.  I rather prefer and trust the manual method personally.

[SingleH]

I did a bit more reading and seem to have missed the Auto-Epap functionality of the ASV machines. Certainly from what I can see CA's are not at the core of his problem but as he can go for hours without experiencing any but when he does have them it then tends to descend into one huge cluster of CA's and OA's together.

I came across an interesting ASV vs iVAPS study comparing the Lumis iVAPS mode vs Pacewave ASV and other machines. The references to controller gain and other industrial control system terms reminded me of some of your previous comments.

It may be of interest or alternatively help you go to sleep!

https://rc.rcjournal.com/content/65/9/1258

[StuartC]

From what I have seen, in clusters of mixed OAs and CAs, one type of event dominates and more-or-less "causes" the other.  If they are basically obstructive, an ASV is unlikely to be the answer and the soft cervical collar or other positional therapy should be.  Perhaps a different size or style collar? 

Thanks for the article.  I don't remember whether I have seen it before but a quick look highlights a constraint that still makes me like the iVAPS.  The study was done with constant RR - not something I achieve.  A deeper read is required, I think.

[SingleH]

In general an OA occurs shortly before the CA' start although sometimes the other way around at least that is what the event logs typically show. When zooming in on a cluster of those events the flow rate shows some disturbances occuring before either events start.

I did puchase a chinstrap which has not been tested yet.

A good night
   

A bad night
   

A zoomed in event cluster
   

[StuartC]

My thoughts are obstructive, and probably positional. Perhaps additional EPAP and possibly even with lower PS since tidal volume is reasonably high. However, I am sure there are many others here who are better able to give you an opinion in that respect.

[SingleH]

Thanks, Im actually doing a small test of incrementally lowering PS by 0.2 whilst extending out Timax by 0.2 to see if I can get his spont cycle up. I was just reading a study advising about treatment emergent CA's taking 2 to 3 months to go away in patients after initiating treatment so its making me think I just need to leave things well alone and see if things bed in.

Loop Gain in Apnea Gaining Control or Controlling the Gain?

I did do a test with a higher EPAP of 12 and a PS of 4 but had no success. He needs somewhere around 13-16 EPAP to clear his apneas and I think he would struggle with higher pressures with even a low PS on top of that.