Therapy using Lumis 150 ST

[Geer1]

No, I am not "chasing higher pressures".  At this point my intent is simply to measure and document how my body responds to a range of pressures, ideally to eventually find a "Goldilocks" pressure that is neither too low nor too high.  That is one approach.

I interpreted below as still chasing higher ventilations still. Glad that your other source confirmed these aren't targets you can aim for. 

Then I plan to progressively increase IPAP to establish the relationships with Vt, MV and RR.  

You have already said S mode with 5 PS stops desaturations and unless you can get capnography data that says otherwise there isn't much reason to continue targeting higher ventilation imo. 

If that interested sure give it a try but the relation most likely is increasing PS causes increasing TV, MV staying the same (approximately with nightly variation), and RR decreasing while BR becomes more prevalent.

[Geer1]

I guess I should be more clear about my opinion.

MV, TV and RR don't matter because you dont know what MV you need to target.

The only things that matter are SPO2 and CO2. SPO2 is easy to confirm with your oximeter. CO2 we can't confirm. Your sleep study that indicated CO2 being an issue with fixed pressure CPAP also indicated desaturations with those settings. There is no data in between that inadequate fixed pressure CPAP and high ventilation AVAPS to confirm at what PS/MV both SPO2 and CO2 issues resolve. My opinion is that all we can assume and should assume is that if your desats are not an issue CO2 likely isn't either.

All you can do for home tests is what you have proposed but all this confirms is at what point your CO2 is low (or better stated as your body believes CO2 is low). This point is determined when inducing extra ventilatory support (higher PS) induces respiratory depression (reduced RR with stagnant MV). This testing only confirms the upper limit of ventilatory support required and doesn't determine minimum or ideal levels. The best we can do to find lower limit of ventilatory support is find what level stops desats which you have already done. Further investigation/titration beyond this requires capnography which is beyond the limits of home titration capability.

Titrating PS in S mode should be based on how you feel using set parameters for say a week at each setting as you appear to have significant night to night fluctuations. I wouldn't focus on MV or TV etc other than as a curiosity to see if they change in a way that supports changes in how you feel (if you start feeling worse when RR starts getting depressed etc).

[StuartC]

Thank you. I appreciate your thoughts and your explanation.

I am sure the gold standard at this point would be to go for another in-hospital sleep study using my Lumis where they hook up a capnograph and the sleep tech titrates the settings during the night. I might get that eventually, but it won't be soon.

Until then, I don't believe that simply setting the lowest pressure that stops desaturations is necessarily the correct pressure. It may be a valuable clinical improvement over fixed CPAP but, if I still wake every morning feeling like crap and walk (hobble) around for the whole day in pain, with low energy, brain fog and other cognitive challenges, it's not enough.

So that leaves me still needing to run some sort of titration process to seek that Goldilocks point where I have no desaturations, the therapy is not causing respiratory depression and I am able to function better.

The method I described appeals to my engineering experience. It provides "open loop" characteristics, which I do value, with indication of when to stop and protection against "too much". It also deals with one variable at a time, whereas we are always dealing with several simultaneously in iVAPS.

[StuartC]

Chart from last night attached. SpO2 was perfect.  Everything else, I am lost for words.

Settings below, red indicates change from the previous night .

• Mode = iVAPS
  
• EPAP = 5
  
• PS min = 6 (IPAP min = 11)
  
• PS max = 9 (IPAP max = 14)
  
• PTR = 11 bpm
  
• Va = 4.0 L/min (MV = 5.3 L/min, Vt = 483 ml, VT/kg = 7.0 ml/kg IBW)
  
• Ti min = 1.0 s
  
• Ti max = 2.5 s
  
• T rise = 900 ms
  
• Trigger = Med
  
• Cycle = Med
  
• Height = 175 cm
  
• Mask = Full (Evora S/M)
  

[Geer1]

Everything else, I am lost for words.

Lol, definitely some interesting/odd looking stuff going on that is tough to interpret. 

RR was finally spontaneous most of the night and it is pretty interesting to see how it fluctuates and gets depressed with the higher PS/MV. You can see at the few spontaneous periods where PS stays around 6 that the spontaneous RR is around 12-13 but soon as the machine tries to force you to breath more RR drops significantly. 

Your exhalations are quite inconsistent and forceful at times but not sure why. Closer details might show some hints.  

Even though target MV was noticeably lower the machine was still significantly active. I am thinking PSmin of 6 may be too high and inducing respiratory depression on its own. This drops RR which lower MV and forces higher PS just making it worse. Also would explain why we kept flatlining on IBR with higher RR and target MVs. I am curious to see if dropping PSmin to 5 or even 4 would reduce this as I think it will. 

Lowering max PS could potentially help kick start higher spontaneous RR and drop machine effort but if min PS is currently too high it could also make things worse by allowing actual respiratory depression and desaturations to occur. 

In short I think you got pretty close to spontaneous breathing effort results but need to drop PSmin for spontaneous breathing to really take over.

[StuartC]

Agreed, PS min needs to decrease.  But 4 or 5?  I have spent the day pondering which as I have to go somewhere tomorrow that is about a 2 hour drive from home - I cannot afford to be too fatigued.

But I looked back through my charts and found one (attached) that lets me think I can go straight to PS min = 4.  In this one, PTR was 12 bpm.  I think I did set based on a Vt target of 480 ml so Va = 4.4, Mv = 5.8 and Vt/kg = 7.  Quite similar figures.

The biggest concern with that night was that IPAP stayed pretty consistently at IPAP max, which was only 12 at the time.  IPAP max is currently 14.  Not sure what the best value would be but, at this stage, I have not changed it.

[Geer1]

I too think you can go straight to 4.

Out of curiosity when you used S mode was it with the same waveform or were you using easybreath (believe that is an option)? One thing to keep in mind is that PS is only part of the picture and the waveform shape also plays a role in how much ventilatory assistance you are getting (since it is the area under the curve that is the amount of assistance by machine). The square wave shape is used by this machine because of the extra assistance it provides although you do seem to have wave shape dialed in pretty good to make it a bit more like easybreath.

That example was looking decent and with the lower MV target I think both RR and PS would have been mostly spontaneous. It is interesting seeing how sometimes like in that example your RR was spontaneous around 12 with a PS of 7 whereas in the last night PS was similar but RR was more depressed. Goes to show you how there is a nightly fluctuation of your spontaneous breathing (which is normal, mine varies around 5.25 to 6.5 MV depending on the night).

One other thing I have wondered about is the Timin of 1 sec, if you look at some of your breaths especially when PS is high the flow rate starts dropping fairly rapidly (giving inhalation a bit of a weird shape instead of rounded top) and I think this is your body trying to start exhaling but the high PS and Timin continues to force a large TV breath. For now I would leave as is and dial in PS, MV etc but this is something to keep in mind (trying a slightly lower Timin) for future as it might help avoid the high TV breaths and force spontaneous RR to kick in sooner.

[StuartC]

There is no easybreath option on this machine.  Instead, and I explained this better in post #2, I manipulated Ti min and T rise to give me a similar wave form to the AS10 Elite CPAP.  I found the square wave with a faster rise time to be quite uncomfortable. I would need to look back again to refresh my memory of how, but I also saw some "odd looking" glow waves that resulted.  The CPAP machine supplier had also told me that T rise could be increased for comfort except for certain groups of people, with COPD being the group that he mentioned specifically mentioned.

I have noticed some breaths being having very sharp peaks and had wondered why.  I had not made the connection you suggest to high PS so that is interesting.  I will need to monitor this and see if I can reduce T rise and T min without it being too uncomfortable.  As with most settings, I suspect, I could probably do it a little at a time.  It is probably the big difference between the AS10 and the Lumis that was the reason for the discomfort when I switched.

I am also aware that the T max that I have set is longer than recommended.  That is because I found I needed that extra time when I first get into bed as I breathe quite deeply then.

Thanks

[StuartC]

I don't have a lot of time today to look closely, but it seems to have worked well.

An interesting observation, not shown on the graph, is that there are leaks reported during the periods where the flow reduces.  Two problems with accepting that at face value: (1) the Evora Full seems to just not leak, at least it has not so far, and (2) I think all three are quite lined up with my previous history of desaturations in REM.  I will need to look more closely later.

Another observation that I made fater setting pressures but before going to be id that PS min = 4 may not be enough.  (1) I had better control of Desats in S mode with PS min = 5.  (2) The controller shot up to maximum pressure and would, presumably, have kept going if it had not been constrained.  I am not against increasing PS max if it is needed and will not automatically just bang IPAP up to IPAP max, but the controller might also have an easier time if PS min reduces the extent of the desat from the beginning, in which case increasing PS max might not be necessary.

For now, I think a couple more nights at this setting would be a good idea. 

Thanks.

[Geer1]

There we go!

I would like to see a zoomed in shot of the period with desaturations and another one of the obvious rem period earlier in the night. If possible I would like to determine how your breathing appears to decline in rem (if it is from it getting shallower, slower RR etc) to understand how to best try and support it. I don't think you should increase PSmin because this appears to work very good 90% of the night. I don't know that I would mess with PSmax either or that it would help much. I think fine tuning RR and MV targets slightly might provide the best support but not sure which one would be better to try first and hoping the zoomed shots might give some hints.

Overall 3 momentary desats to only 91% are not too much of a concern but it might be a sign of there still being some room for improvement. There were some TV spikes at the same time which might have been post arousal because of the desats or maybe the desats were post arousal because of momentary hyperventilation.

I wasn't sure about S mode easybreath, it is an option on S mode on S machine so thought it might be on this one (but only in that mode, won't be in ST or IVAPS). I would leave rise time as is as that makes it more comfortable, shorter rise time makes the pressure wave more square/forceful and I don't think that is necessary or helpful in your case. Timin was maybe on the high side but it might be fine now with this lower PS, I believe it was a contributing factor to the respiratory depression when ventilation targets were too high and part of the reason your breathing used to get stuck on large TVs. Timax isn't that important and I don't see any reason to shorten it in your case.

In short I think we are already pretty close and think some minor fine tuning with RR and MV targets are next but part of me thinks you should just continue to use these settings a few nights to see what the nightly variations look like although if zoomed shots offer any obvious hints we can make changes now.