AVAPS-AE on MY Trilogy - Ongoing

[Madalot]

So, do you agree that if nothing else comes to light today that my making the increase to max EPAP 11 tonight reasonable? It might be interesting to see if the higher max EPAP changes the pulses in any way. I'm game.

[-SWS]

I don't see a grave risk in increasing Max EPAP to 11cm tonight, Madalot.

Recap notes.

1) Madalot is gradually exploring an auto-EPAP range of 9cm through 12cm (auto-EPAP range applied against old AVAPS side-sleeping settings as baseline)
2) Waning tidal volumes might warrant increasing Max Pressure above 23cm (adjust PS-range's ceiling)
3) Over-ventilation or discomfort during side-sleeping might warrant dropping Min PS below 9cm (adjust PS-range's floor)
4) After exploring auto-EPAP 9cm through 12cm, Madalot might decide to explore auto-backup rate, 8cm backup rate, and/or lower Min EPAP values with continued doctor approval
5) Hoping to gradually explore changes to one treatment dimension at a time--or as few as possible---to help isolate emergent treatment problems (e.g. Madalot's initial PTB plummet)

Jnk asked about a possible need to increase Max Pressure along the way. Madalot might have to. But I still recommend increasing Max Pressure only if tidal volumes wane a bit with any given Max EPAP increase, but especially when side-sleeping.

With Min EPAP 9, Max EPAP 11, Min PS 9, Max PS 14, and Max Pressure 23, these will be the allowable PS ranges, per auto-EPAP value:

@auto EPAP 9===>PS 9cm through PS 14cm
@auto EPAP 10===>PS 9cm through PS 13cm
@auto EPAP 11===>PS 9cm through PS 12cm

The old AVAPS side-sleeping settings used fixed EPAP 9cm, allowing PS 9cm through PS 14cm
The old AVAPS supine-sleeping settings used fixed EPAP 12cm, allowing PS 6cm through PS 11cm

We can see the above side-sleeping comparison is where Max Pressure 23cm MIGHT cause tidal volumes to wane just a bit. I would suggest raising Max Pressure only if needed, since 23cm above atmospheric pressure is quite a bit---and 24cm, 25cm, and 26cm amount to even more pressure above atmospheric pressure. More importantly, if the medical staff suggests different values, then I would suggest deferring to those settings.

Good luck.

[Madalot]

Thank you, SWS, for the recap again. I have been using it for reference and will continue to do so through this experiment. I have already set the trilogy to Max EPAP of 11 for tonight. I've decided to go back, for now, to flow trigger rather than auto Trak.

I am anxious to see if the pulses continue or are better or worse with the increased EPAP.

[mollete]

I am anxious to see if the pulses continue or are better or worse with the increased EPAP.

They will stay the same (1.0 cmH2O at a rate of 5 Hz. during EPAP).

Also, they should be referred to as FOTs (pressure pulses are a different airway patency scout).

[Madalot]

I am anxious to see if the pulses continue or are better or worse with the increased EPAP.

They will stay the same (1.0 cmH2O at a rate of 5 Hz. during EPAP).

Also, they should be referred to as FOTs (pressure pulses are a different airway patency scout).

Once again -- excuse my ignorance, but FOT's?

[-SWS]

Forced Oscillation Technique (FOT) is the term for those pulsations, Madalot. Their purpose is to test for aiway patency---apparently toward facilitating AVAPS-AE's auto-EPAP...

Most interesting that Respironics is using FOT on the Trilogy but not their xPAP machines---unless they recently deployed FOT on their xPAP machines also.

[jnk]

Are we sure those traces of FOT oscillations are the same "pulsations" Madalot is experiencing as uncomfortable and irritating? Could what she is experiencing be something other than that?

Can you describe what the "pulsations" feel like, Madalot? Are they large puffs that seem to be seconds apart? Or do they feel almost like small continuous vibrations?

Maybe you already described them in detail, and I missed it, earlier.

[mollete]

Most interesting that Respironics is using FOT on the Trilogy but not their xPAP machines---unless they recently deployed FOT on their xPAP machines also.

Trilogy has been traditionally used to treat chronic respiratory failure. These patients may already have significant pressure support in order to successfully do that. Within that group are patients who have SDB as well (Overlap Syndrome). It has been suggested that FOT has a better ability to assess airway patency at higher pressures.

[mollete]

Are we sure those traces of FOT oscillations are the same "pulsations" Madalot is experiencing as uncomfortable and irritating?

Yes.

Could what she is experiencing be something other than that?

No.

[-SWS]

As a recap, here's DreamDiver's graph comparing Resmed's FOT method with Respironics' patency detection used on their PR System One xPAP machines (a non-FOT method):


viewtopic.php?p=475717#p475703

The short, green oscillations above show Resmed's FOT implementation on their S9 machines (labeled ".5cm H20 average"). The tall, green square-wave pulse shows Respironics' non-FOT method of detecting airway patency (labeled "Respironics 'clear airway apnea' detection mask pressure comparison"). We can see on the PR System One machines, that Respironics was not using FOT---at least back then they weren't.


Anyway, now we can see that Respironics Trilogy's AVAPS-AE modality uses a FOT airway-patency detection method:



I'm curious if the newest Respironics xPAP machines now use FOT.

[mollete]

You kids are going to love this.

The pulsations occur in a pattern:

• The beginning of an EPAP change.
• The end of an EPAP change.
• In the middle of the changes.

As if it were an auto-EPAP design characteristic of some type...

I concur that I see pulsations in the pattern you described. I see three such complete patterns, starting with this first sequence:
1) a cluster of pulsations...

And interestingly, the cluster is always 10 breaths.

[Madalot]

Its obvious to me that several of you have spent a lot of time and effort in the last day or so to investigate this for me. For that I am very grateful.

If I'm understanding correctly, these FOTs are by design and not mechanical issues. This brings me to yet another question.

Will I experience these FOTs every night or will they eventually stop after the system figures out what it needs to do?

[-SWS]

You can expect these FOT oscillations every time AVAPS-AE is enabled and Max EPAP is set higher than Min EPAP. Respironics will use those oscillations to facilitate EPAP changes. As a side note, most people are probably not sensitive enough to be bothered by them... Hence jnk's question. Mollete's answer indicates that he could find nothing else in your waveforms to account for the oscillations you feel.

[Madalot]

These are very noticeable. They're pretty strong and not something that could be easily slept through. The best way for me to describe it is that instead of a smooth exhalation, it's more like my exhale is going putt putt putt. Does that make sense?

[-SWS]

If it's any consolation, this message board has a few people who cannot tolerate Resmed's S9 FOT (small-amplitude sinusoid), and a few more who cannot tolerate Respironics' non-FOT airway-patency detection method (a single square-wave pulse). Most people can't feel those two airway-patency detection methods. This is a third method (also sinusoidal FOT---albeit larger amplitude). The jury's still out regarding how many/few this airway-patency detection method will bother.