Therapy using Lumis 150 ST

[StuartC]

It has been a long time since I did this but, on a chemical plant where oscillating outputs happen, I would start by reducing the proportional gain - especially on a flow loop or a low-volume, fast-acting pressure loop. Might need more integral action but even then, good open loop control is frequently the key.

So, were my "dreams" good last night? PS min?

[Rubicon]

And on Sunday you have an entirely different frequency response:





~50 second cycles on Monday, ~150 second cycles on Sunday.

[StuartC]

Different RR? Also Sunday was when I tried "very low" trigger.

[Rubicon]

Let me add something quick in case something happens to me...

April 1 and 2 look very good, in the S mode, but IDK if Oscar accurately receives the setting data correctly so be sure to use the settings on the machine instead of what Oscar has.

If you want to continue fiddling with iVAPS I think a stable MV for you is ~6.0 L. so set the iVAPS at 5.5 L. (don't let it engage till it needs to) and check the spontaneous%s and O2 sat%.  Drop MV 0.25 to 0.50 L/day till you get the pattern you want.

[Rubicon]

Different RR?  Also Sunday was when I tried "very low" trigger.

No Rate was 12, I think it's the MV, at >7.0 L you get the long cycle stuff, 6.0 - 7.0 L you get short cycle stuff, and <6.0 L you're stable.  

BRB, getting called to the principal's office.

[StuartC]

17th was RR = 12, very low trigger, 18th was RR = 11. med trigger.

OSCAR is reporting S mode pressure settings correctly. if in doubt look at the statistics panel bottom left.

You are losing me with the MV. Target learning said MV = 7.2 @ RR of 13, which was spontaneous RR of 1 & 2 April. So, was that exercise of no use?

Also, MV of 6.0 at RR of 13 (spontaneous rate on S mode) gives VT = 460. That is similar to CPAP, where I had high CO2. Isn't the point to get volumes higher? Are you thinking that it cannot be done without oscillations?

[Rubicon]

Target Learning was helpful information.  It showed how you breath while you're awake.  However the information gained may not be helpful.

Capping PSmax prevents iVAPS from completing it's algorithm.  You can't give it a task, prevent it from completing it and then pass judgement.  However, the limit made therapy effective.

That said, the chemoresponsiveness++ is something new and needs to be added into the mix.

pCO2 rises a little upon taking sleep, like several mmHg.

Priroity #1 in this whole thing is finding out why the pCO2 is high in the first place.  Until then, all this is Dial Wingin'.

Previously noted:  "You would like all breathing to be spontaneous otherwise you could be driving your pCO2 into God knows where. That said, given the history, you should probably see machine breaths during REM periods cause that's where the central hypoventilation occurs. That said2, machine breaths all night means settings are too aggressive. That said3 based on O2 sat and breathing pattern the settings don't look all that bad. That said4 what you're really trying to do is manipulate pCO2 (normalize during REM, don't overventilate in NREM) so you really need some capnography to get this correct."

In re: oscillations.  If the cause of the increased pCO2 is uncovered and corrected then all this starts all over again.  Speaking of which, you can also get elevated pCO2 from a metabolic alkalosis unrelated to this so you could have multiple issues.  So IDK where the oscillations will end up at.  But they're interesting as all getout, huh?

[Geer1]

As Rubicon has noted your ventilation seems to get stuck targeting too high of ventilation. This appears to create some sort of weird silhouetted oscillation I haven't seen before (I would be curious to see a more zoomed in example to understand why the peak appears to stay constant but there seems to be oscillation in the breathing).

Imo part of this is because of the difference in how Philips Respironics AVAPS works compared to Resmed IVAPS and that you started titrating IVAPS using the recommended AVAPS settings. The bigger part of this is probably because the titration study was targeting a fairly high TV target of 8.4-9 ml/kg (average is usually considered around 7 ml/kg). This may be due to their experience with AVAPS (perhaps targeting a high ventilation works better with it) although I kind of feel you would have struggled on that setting even if using PR AVAPS. Regardless this combination led to targeting too high of ventilation with Resmed IVAPS which has been determined.

Decreasing MV target until you see respiration stabilize is an option and will give you what I would consider an upper limit of settings that work for you.

If you look up Resmed titration protocol they recommend the opposite with starting low on target ventilation and increasing as necessary to treat desaturations (which is ultimately what you are trying to do). They recommend starting at 6 ml/kg ideal body weight (for your height of 176 cm is 70 kg) which results in an initial target Vt of 420 ml.

As for the target learning recommended settings I am yet to see someone have success using it. I imagine it would work if someone else could run it while you are sleeping but everyone that I have seen run it while awake ends up over ventilating themselves with the recommended settings due to measuring awake breathing not consistent with sleep breathing requirements.

Your comment about Rubicon's most recent recommended target being close to CPAP results where you had high CO2 is mistaken because you are assuming you had high CO2 all the time when on CPAP and that you need to target higher ventilation at all times and notice a significant increase in overall ventilation statistics. Your desaturations and high CO2 primarily occur during rem sleep which only makes up a small portion of overall sleep. Your average statistics should be similar and in your case you could probably assume that your spontaneous respiration rate and TV on CPAP when not in rem sleep (easy to look at some examples in OSCAR to determine an average while avoiding obvious rem breathing) provides you with adequate ventilation and should be your approximate targets with this machine. The increased PSmin of 4 is already going to give you a minor boost compared to when you were on CPAP already.

The other thing to note is that once you find ideal target/settings I wouldn't be surprised to see the machine drive respiration rate during rem sleep (at least at times) but hopefully what we will see is that it won't continue to drive respiration all/most of the time like it currently is.

Oh and I would leave sensitivities at normal unless you can see some sort of sync issue.

[Rubicon]

[StuartC]

Thanks for joining the conversation Geer1.  You have raised quite a few interesting and important points.  I have not worked out how to use the multiple quote feature of this forum, so I will just use italics when I am quoting anything from your post or anywhere else.  Please bear with me.

I absolutely agree with you when you said "Imo part of this is because of the difference in how Philips Respironics AVAPS works compared to Resmed IVAPS and that you started titrating IVAPS using the recommended AVAPS settings."  Right at the very beginning of this thread, I said "This is where I start asking for help checking my translation of settings from Philips to ResMed."  I think that is still part of what we are dealing with.

I need to respond to where you said "Your comment about Rubicon's most recent recommended target being close to CPAP results where you had high CO2 is mistaken because you are assuming you had high CO2 all the time when on CPAP and that you need to target higher ventilation at all times and notice a significant increase in overall ventilation statistics. Your desaturations and high CO2 primarily occur during rem sleep which only makes up a small portion of overall sleep. Your average statistics should be similar and in your case you could probably assume that your spontaneous respiration rate and TV on CPAP when not in rem sleep (easy to look at some examples in OSCAR to determine an average while avoiding obvious rem breathing) provides you with adequate ventilation and should be your approximate targets with this machine."

No, I am not assuming that I had high CO2 all the time while on CPAP, that is what the capnograph from the sleep study shows (image attached showing only pertinent parts from the charts page with additional coloured bands overlaid to help show periods of CPAP and BiPAP). The sleep study also states "Transcutaneous CO2 monitoring showed TcCO2 levels were 39 mmHg when awake, increasing to 50 mHg during NREM sleep with CPAP therapy but reducing to 41 mmHg during NREM sleep with BIPAP+AVAPs therapy." 

This is what is driving me.  Fixing the oxygen desaturations is easy.  I did that with S mode EPAP = 5 and IPAP = 10 (Front page of O2ring report attached).  However, on that same night, my median Vt was  still only 440 ml, similar to CPAP, but compared to a volume of 600 ml used in the sleep study.  I have no certainty (or confidence) that simply correcting the hypoxia also corrects the hypercpania.

I agree with you where you said "The other thing to note is that once you find ideal target/settings I wouldn't be surprised to see the machine drive respiration rate during rem sleep (at least at times) but hopefully what we will see is that it won't continue to drive respiration all/most of the time like it currently is." 

Since I know that I desaturate during REM, I would hope to see the machine provide simple pressure support from EPAP to PS min with spontaneous breathing during NREM and then have the machine take over and do its thing during REM.  That might include both increasing PS in response to reduced volume and controlling respiratory rate if my spontaneous rate slows down.  What I did not appreciate, and what Rubicon has alluded to when he said "Capping PSmax prevents iVAPS from completing it's algorithm" is that these two mechanisms of control appear to be tightly connected when I have been treating them as independent.

I have more to report based on Rubicon's information and last night's sleep, but I will separate that into another post.  Please allow me a little while to type it all up.  Thank you once again for joining the conversation.