Therapy using Lumis 150 ST

[StuartC]

Charts from Mon 25 April.  I have added two from the whole night.  One is the usual data.  I have added the other just to show how pulse rate reacted to fixed RR early in the night (but not towards the end).  I have put mask pressure and pressure on that one just because I had space on the chart and nothing better to put there.

Please let me know what zoomed charts you would like to see.

I am pondering why I breathe so deeply when I get into bed, which we see on the charts as high Vt with lower RR, which seems to precipitate fixed RR.  In particular, I am wondering if it is affected by the routine I follow.  I might change that up a bit over the next few nights and see if there is a difference.

I am also wondering if I can continue iVAPS mode much longer if it does not come right.  I have been able to do all of this experimenting because I have been on a school break.  But I have done no work during this time and I still have a lot of marking and prep to do before term starts again next week.  As much as CPAP / S mode is not ideal, days like yesterday , and a few others, are a disaster for my productivity.

[Geer1]

More machine interaction than I expected. In part it seems to have been a low MV night 5.75 average vs 6+ most nights) so the machine had to operate more. After the machine takes over it seems like your body just goes with it. I am curious what your inspiration time was when machine was driving respiration. If it was 1 second then I think you should try reducing Timin. I believe default timin is only 0.3 and would probably try that.

Many people have high TV first thing that drops similar to yours. Awake breathing has higher respiratory effort and when you put on the mask at first it is natural to take large breaths with the extra assistance the machine gives.

[StuartC]

Another thing worth looking at now is timing controls and how in sync your breathing appears to be with machine operation. If your body is fighting the machine like say trying to exhale while machine holds pressure or supplying pressure before you are ready for it then that can also cause fatigue.

We can look at that last night where spontaneous trigger rate was only 58%, cycle was 97%.  But that is surely not a factor on days like yesterday where I had spontaneous trigger of 99% and cycle of 98% the night before. 


What I noticed last night was that the VAPS control was really steady with IPAP in the 12 to13 range when RR was controlled to a fixed 12 bpm.  But IPAP was quite reactive during spontaneous RR less than 12.  In theory (that's control theory, no idea about respiratory theory), the controller might work better with a smaller output range.  But the the 12 to 13 range that it worked at last night means we would only have scope to reduce PS max by 1, so reducing the range might also require increasing PS min.  Not a great solution all round.

I have to wonder whether iVAPS is designed to be used with fixed RR rather than spontaneous RR.

The other thought that I had is that I am trying iVAPS because AVAPS was used in in the sleep study.  Quite aside from the 600 ml Vt target, apparently it was set with EPAP = 8, IPAP min = 14 and IPAP max = 23.  But the pressure graph does not show anything more than an IPAP of 12 apart from a couple of small "blips" to, perhaps, 13.  So the chart seems to not match the text.  Not sure where that leads other than I am ready to abandon iVAPS.

[StuartC]

I am curious what your inspiration time was when machine was driving respiration.

Chart attached.  I cannot see Ti less than 1.28 s.  The chart has a minimum Y axis value of 1 and does not show Ti close to that.

300 ms is the default for T rise.  The Clinical Guide for the Lumis recommends Ti min to be set to 1 for RR in the range of 10 to 15, decreasing to 0.8 for RR of 20.  The Titration Guide recommends Ti min of 1.5 s for restrictive lung diseases but 300 ms with T rise of 150 ms for obstructive lung diseases. 

I have also attached a 4 minute flow and mask pressure chart of a hypopnea that I experienced on the only night that I had T rise at 300 ms for you to look at.

[StuartC]

The Titration Guide recommends Ti min of 1.5 s for restrictive lung diseases

Sorry, that is Ti max of 1.5 s.  Ti min is 0.8 s.

[StuartC]

Chart attached for the night of Tuesday 26 April.  Spontaneous trigger was 67%.  The second period of controlled RR, at about 5 am, might have been REM related, so I am not bothered by that.

I had a thought about whether there would be any value in turning on the ramp feature at the beginning of the night to delay the start of pressure control.  The Clinical Guide says that during ramp, EPAP is ramped from a start value to the set EPAP value (I could possibly set these to be the same or, at least, set EPAP start very close to 5) and that IPAP is fixed at PS min.  Effectively, it switches to ST mode.  But the guide says nothing about iBR, which is an option in ST mode too, so I presume iBR would still be active from the beginning.  That probably means that using ramp will not have any benefit directly but might if the drop in RR is as a result of the pressure controller increasing IPAP above IPAP min.

[Geer1]

I am torn on what to do next.

I feel like we are kind of close but even minor changes like the increase to 12 RR have a significant and somewhat unexpected influence. When forced to breath spontaneously with 11 target RR you did so with RR barely dropping to the IBR initiation point and majority of the time RR was over 12. Just increasing RR target to 12 all of a sudden caused a bunch more depressed RR (around half the night under or held at 12 RR) more machine support (median PS increased from 4 to 6/6.5) and lower median MV even though target was higher (median MV decreased from 6.2 to 5.8).

I feel like IVAPS should be the ideal solution for these momentary respiratory depressions but for whatever reason it just doesn't seem to agree with you. If you want to try ST mode I am curious what that would look like in comparison. I would probably use PS of 4 and BR of 11.

I would also be curious to get a link to data to take a close look and see that there isn't anything that stands out.

[StuartC]

I am also torn but I think back to ST mode is sensible. 

I realised that the Lumis has the progression of modes from S, to ST with fixed BR, to ST with intelligent BR and then to iVAPS. I jumped from S to iVAPS and that did not work so well.  Maybe that is not entirely surprising.

I also think I need to ease off a bit until I can see an appropriate specialist.  I have received a copy of my lung function test results and an assumption of a restrictive lung disorder does not appear to be obvious. 

• From the spirometry test, my FEV/FVC ratio is 0.64, which I understand is more consistent with an obstructive disorder.  However the ratio may not be a useful indicator since my FEV is only slightly lower than expected and my FVC is actually higher than expected.  The summary conclusion is "Normal spirometry".
  
• The CO diffusion test showed that both DLCO and KCO higher than expected (about 135%), which is summarised as "elevated gas transfer".  However the report does list a couple of possible causes for this, the most interesting of which is a left-to-right cardiac shunt. 
  

I also got results from CT and PET scans that reported negative results for sarcoidosis and interstitial lung disease or fibrosis.  All good news there.

To be sure, this has not been a wasted effort.  I have learned a tremendous amount.  In addition, the increased PS achievable with the Lumis eliminates the SpO2 desaturations, which the EPR from the Elite could not. 

EPAP = 5 and PS = 4 are logical for ST mode.  When you say BR of 11, do you mean fixed BR?  I can try that but I know I found it difficult in the sleep study when BR was 12, so I might end up reducing it to 10, as suggested in the report.

I will send you a pm with a link to a Dropbox folder containing a copy of my SD card and the associated O2ring downloads.

Thanks

[Geer1]

Yeah thinking fixed back up rate to try and kick in sooner rather than waiting until respiration is already depressed before the machine provides assistance.

10 might be necessary but I was hoping 11 would work. Usual recommendation is 2 less than spontaneous which would be 11.

[StuartC]

Chart attached for the night of Wednesday 27 April.  ST Mode with EPAP = 5, IPAP = 9 (PS = 4).  Fixed backup rate of 11, which I tolerated fine.  Spontaneous trigger was 89% and cycle was 98%.

Desats occurred as per CPAP, but did not drop as far.  MV chart is interesting, but not entirely different to previous CPAP / S mode.  Median Vt was 420 ml,which is lower than we have been achieving on iVAPS. 

The plan is just to do a few nights with the same settings to settle in.  At some point, I might try iBR instead of fixed BR since it might let me increase PTR to 12 (or, dare I suggest, perhaps even 13) but with the lower trigger value.  It will be interesting to see any differences and I think I need to do this if I am going to be able to get back to iVAPS mode.

I am also still intrigued by the night where I switched masks (16 April, see post #9 and post #18) so, once I have a reasonable number of nights to compare with, I might try the Vitera mask instead of the Evora to see if there are any notable differences.

Still so much to learn.