Help with self-titrating BiPAP for UARS - low % of spontaneously triggered breaths?

[Sleeprider]

In your first post we see settings of 7.6/5.0 (PS 2.6), 14.8/5.0 (PS 9.8) and 15.0/6.0 (PS 9.0). These last two are ridiculously high pressure support settings and is disrupting your normal respiration resulting in artificially high tidal volume 520, 780 and 800 mL respectively. This has suppressed your respiration rate to about 10 breaths per minute compared to the normal 16.5 at 7.6/5.0 and affected the time of respiration. Unless your VPAP S is very different from the one we get in the U.S. it does not have a backup rate, that would be on the ST. Most people would have responded with central apnea to this assault, but you have not had that. You need to limit your PS to a range of 4.0 to 5.0. This will fully meet your respiratory needs and resolve any flow limitation from UARS, without transferring all of the respiratory effort to your machine. A setting of 10.0/5.0 is the maximum you should be considering, and this may feel uncomfortable when you first switch back to this because you have allowed yourself to become dependent on pressure support to do all the respiratory effort. What you are doing will hurt your long-term health. Stop it! You may need a respiratory assist, but you do not need a ventilator, and that is what you're doing.

Can you post a closeup image of your flow rate and the mask pressure graphs? I'd like to see if you're getting the Easybreathe shaped pressure, or if you are getting a square wave. Do you have an option to turn on Easybreathe? What version of Oscar are you using? Should be 1.5.1. I am asking because the therapy mode is labeled BiPAP S and it should be VPAP S.

[zaienk]

Your are washing too much CO2 because of your high PS so you are breathing because of the backup rate of 10 that is available on recent aircurve 10 vauto, only on bipap S mode with easybreath desactivated.
That could be. I don't have the Vauto device though

You can see on your chart that you are breathing around 15 time per minute with low PS and around 11 times per minute while using very high PS, which is not you should expect.
I would expect resp. rate to go down if tidal volume increases in order to maintain minute volume. I would argue that I'm finally getting enough air per breath causing the resp. rate to go down.

I would be you, I would switch back to vauto mode with trigger high or very high, a confortable EPAP, starting back with a PS of 4 or 5 and slowly increase if needed the PS while leaving IPAP on 20 or 25 to see how the machine manage your EPAP according the flow limitation detected.
Unfortunately I don't have Vauto, so that won't be possible. Increasing trigger sensitivity is a good suggestion though. If CO2-washing really is the cause then I guess I'll have to roll back the PS and increase EPAP over time, right?

I trust that you have activated backup rate ? I trust that on this model, you have the option of backup rate of 10, you can't change the value. My thought is that if you desactivate it, you will get a crazy number of central apnea with you PS of 9, you're getting that much oxygen that it will suppress your willing of breath. 

Sorry I trust that you got a recent aircurve 10 VAUTO like me, after some search, I took it in germany as Aircruve 10 VAUTO that are sell in this country have all parameters available (trigger, cycle etc)

Yes like sleeprider told you, I encourage you to roll back on a PS of 4 or 5, start with a confortable EPAP, i don't know how much you are using now, also desactivate the backup rate if you're sleep study doesn't indicate central apnea, turn on easybreath and follow the resmed titrration method.

If you get obstructive apnea, increase the EPAP on 1 next night while keeping difference between epap and ipap constant, usually 4 when you start the titration.
Once you find the EPAP which keep you safe of obstructive apnea, start to increase PS very slowly to get ride of hypopnea, RERA, snoring, without triggering central apnea.

Trigger parameter set on high or very high is very useful to "kill" central apnea induced by using a higher value of PS .

[Bibbbooker]

Could you explain why you ended up with an AirCurve 10 S? Dr recommended? Your sleep study showed central sleep apnoea’s? It was what was available?

Unfortunately there is only one clinic in the Netherlands which even recognizes UARS, and it has a 5-month waiting list. After numerous different sleep studies indicating something fishy(they don't score RERA's) and direct confirmation on a WatchPAT, I felt confident enough to self-diagnose UARS(doctors don't do that here).

After reading a lot of recommendations regarding PAP-treatments for UARS on forums such as this this one, but also watching a lot of videos on youtube by Thelankylefty, Barry Krakow and others, I settled upon buying a Bilevel for S mode. 

In your first post we see settings of 7.6/5.0 (PS 2.6), 14.8/5.0 (PS 9.8) and 15.0/6.0 (PS 9.0).  These last two are ridiculously high pressure support settings and is disrupting your normal respiration resulting in artificially high tidal volume 520, 780 and 800 mL respectively.  This has suppressed your respiration rate to about 10 breaths per minute compared to the normal 16.5 at 7.6/5.0 and affected the time of respiration.

While I agree that the PS is ridiculously high, couldn't it be that I need a (slightly) higher PS due to my height and weight? I have found numerous formulae for "normal tidal volume" during sleep and none of them consider 780 or 800 to be exceptionally high for someone my size.

Unless your VPAP S is very different from the one we get in the U.S. it does not have a backup rate, that would be on the ST.   Most people would have responded with central apnea to this assault, but you have not had that.

Apparently newer European Resmed bilevels have a backup rate that can be turnt of. So in reality their bilevel S is more of an S/T. I think you are right when it comes to the central apneas - in this case the backup rate prevented me from getting them.

You need to limit your PS to a range of 4.0 to 5.0. This will fully meet your respiratory needs and resolve any flow limitation from UARS, without transferring all of the respiratory effort to your machine.  A setting of 10.0/5.0 is the maximum you should be considering, and this may feel uncomfortable when you first switch back to this because  you have allowed yourself to become dependent on pressure support to do all the respiratory effort.

Where do these limits that you mention come from? If RERA's and/or flow limitations persist, wouldn't it make sense to up the PS?

Also, could it be that I need higher EPAP than the 5cmH2O you mentioned here, despite not having apneas? I am a national level strength athlete and consequently have developed neck, chest and back musculature that might be restrictive when it comes to breathing. Because I am still relativelly lean and young, this might not directly lead to apneas but I definitely think it could be restrictive. I'm inclined to think that EPAP might be helpful in alleviating this restriction but am interested in hearing your thoughts.

What you are doing will hurt your long-term health. Stop it!  You may need a respiratory assist, but you do not need a ventilator, and that is what you're doing.

The backup rate is what prevented me from getting central apneas and is what led to the low % of spontaneous triggers. With the backup rate on, this setup could very well be considered a ventilator. I have since rolled back the PS to 5 and turned of the backup rate (more on that below). However I am wondering, is there still harm in higher PS if I am not getting central apneas and not flushing CO2? For context: I work out 12 hours a week and my respiration is objectively very strong when measured on a Powerbreathe. Cardiovascular fitness is good too.

Can you post a closeup image of your flow rate and the mask pressure graphs?  I'd like to see if you're getting the Easybreathe shaped pressure, or if you are getting a square wave. Do you have an option to turn on Easybreathe?  What version of Oscar are you using? Should be 1.5.1.  I am asking because the therapy mode is labeled BiPAP S and it should be VPAP S.

Unable to post another picture due to the data cap, but it is indeed a square wave. Unfortunately my device doesn't offer airbreathe, but I did increase "rise time" from 100ms to 200ms last night. This has mostly restored the shaped of the flow curve.

Oscar is version 1.5.1. Are you sure it should say something different? The device I have is called "ResMed AirCurve 10 S BiPAP Device", which in reality is more of an S/T device due to the backup rate they sneaked in there.

I trust that you have activated backup rate ? I trust that on this model, you have the option of backup rate of 10, you can't change the value. My thought is that if you desactivate it, you will get a crazy number of central apnea with you PS of 9, you're getting that much oxygen that it will suppress your willing of breath.

 
Agreed.

Sorry I trust that you got a recent aircurve 10 VAUTO like me, after some search, I took it in germany as Aircruve 10 VAUTO that are sell in this country have all parameters available (trigger, cycle etc)

Apart from not having the VAUTO-mode/algorithm and Easybreathe available, you are correct in all your assumptions.
 

Yes like sleeprider told you, I encourage you to roll back on a PS of 4 or 5, start with a confortable EPAP, i don't know how much you are using now, also desactivate the backup rate if you're sleep study doesn't indicate central apnea, turn on easybreath and follow the resmed titrration method.

If you get obstructive apnea, increase the EPAP on 1 next night while keeping difference between epap and ipap constant, usually 4 when you start the titration.
Once you find the EPAP which keep you safe of obstructive apnea, start to increase PS very slowly to get ride of hypopnea, RERA, snoring, without triggering central apnea.

Trigger parameter set on high or very high is very useful to "kill" central apnea induced by using a higher value of PS .

Based on what you and others wrote in this thread I made some changes. As a consequence, I had 100% spontaneously triggered breaths and - more importantly - an uninterrupted (though short) night for the second time since starting treatment! It's too early to tell how this affects my symptoms but I'm optimistic.

The changes I made:

1. Turned off backup rate so that I am no longer on a ventilator.
   
2. Lowered PS to 5 in order to prevent a high number of central apneas.
   
3. Increased EPAP to 8 as I was set to do so and past increases made me sleep and feel better.
   
4. Increased "trigger" from med to high in order to mitigate too high an increase in central apneas.
   
5. Increased "rise time" from 100ms to 200ms in order to restore flow curve shape and reduce CO2 washing.
   

These changes have made my flow rate graph and respiratory rate less volatile while only giving me 3 central apneas total over 6 hours of sleep. Median tidal volume and respiratory rate were at 540 mL and 17 bpm respectively.

I will keep these settings for a week to see how I'll respond before making some more minor changes to see if things can improve further.


Thanks everyone for your thoughts and suggestions, I truly appreciate it.

[Sleeprider]

Your VPAP S should have Easybreathe.  Easybreathe works to increase or shape the pressure rise to a more natural wave-form. This image shows the flow rate and mask pressure using Easybreathe.  I'm sure it is available on your machine, but it must be turned on. If it is off, the rise-time control is visible.

[Bibbbooker]

Thanks again for your reply Sleeprider. 

You keep referring to my machine as a VPAP, why is that? Just to be sure, the one I bought is called "ResMed AirCurve 10 S BiPAP Device" in the CPAP Europa store and differs from the "ResMed AirCurve 10 VAuto BiLevel Device". 

The machine I bought likely lacks the special algorithms such as VAuto and Easybreathe because in the clinical menu under settings there is no Easybreathe option. Instead, between "EPAP" and "Ti max", it says "backup rate". This can be set to "off" or "10". Resetting to factory defaults doesn't change anything in this regard. Unless there is a particular setting I need to change in order to get the Easybreathe option, my machine doesn't have it.

In the unfortunate case that my machine doesn't have Easybreathe, would you be able to recommend a "rise time" setting?


All the best,
Bibbbooker

[Sleeprider]

VPAP (variable positive air pressure) is the Resmed name for bilevel therapy, and has been used by them in the name of their devices (VPAP-S Vauto) for a number of generations. The term BiPAP is actually a proprietary term for a Philips bilevel therapy and device and is used in the names of those devices. I guess I don't always fall in the trap of calling a tissue, "Kleenex". So I will always use either the term bilevel or BPAP generically, or VPAP with Resmed, BiPAP with Philips.

Your VPAP S is quite different from the North American version and the availability of a backup rate makes this a ST (spontaneously-timed) bilevel. The backup rate should normally be set 3 breaths less than the normal spontaneous rate. Your spontaneous breath rate on the January 6 chart was 16.4 and I assume your breath rate with PS 5 was close to that. I'm fairly certain a backup rate of 10 is too low, but more importantly, it means that very high pressure support clearly suppresses your respiratory drive. This results in your BPM being equal to the backup rate. You significantly over-ventilated and this was reflected in greatly skewed respiratory statistics with short inspiration time, very long expiration time where no inspiratory effort is made followed by a machine-triggered breath. We can calculate an appropriate tidal volume for your height and ideal weight, but I have coached thousands of individuals on this forum over a number of years. I do fairly quickly recognize when tidal volume is outside the expected range, with 9 to 10 cm of pressure support, that describes you accurately. Do you need more than the preceding explanation to understand the extent to which you have disrupted natural respiration and turned your device into a ventilator, losing spontaneous respiration capacity? I don't mind discussing it and pointing you to so technical references, but I'd like you to have some confidence I actually might know what I'm talking about.

The reason your breaths appear flow-limited or have flat peaks is an artifact of the bilevel algorithm being used with a square-wave pressure support. We have seen this frequently with user of the VPAP ST on our side of the pond. Using a longer rise-time is an appropriate mitigation, but as long as pressure support is high enough to supplement your respiratory volume, you will probably see that flat inspiratory peak. When you start seeing spontaneous breath rates below 100%, your PS is at levels that is suppressing your respiratory drive. This would be very apparent if you turn off the timed backup rate, and those pauses may become UA apnea or hypopnea. With a PS of 5.0 cm, you should have mitigated all upper airway resistance and be seeing normal volume and rates of respiration. I don't know where your apneic threshold lies, but going higher risks hitting it.

[Bibbbooker]

VPAP (variable positive air pressure) is the Resmed name for bilevel therapy, and has been used by them in the name of their devices (VPAP-S Vauto) for a number of generations.  The term BiPAP is actually a proprietary term for a Philips bilevel therapy and device and is used in the names of those devices.  I guess I don't always fall in the trap of calling a tissue, "Kleenex".  So I will always use either the term bilevel or BPAP generically, or VPAP with Resmed, BiPAP with Philips.

Thank you for the explanation. I see a lot of people referring to bilevel devices as BiPAP (even the store I bought it at) so I figured it was custom.

 

This results in your BPM being equal to the backup rate. You significantly over-ventilated and this was reflected in greatly skewed respiratory statistics with short inspiration time, very long expiration time where no inspiratory effort is made followed by a machine-triggered breath. We can calculate an appropriate tidal volume for your height and ideal weight, but I have coached thousands of individuals on this forum over a number of years. I do fairly quickly recognize when tidal volume is outside the expected range, with 9 to 10 cm of pressure support, that describes you accurately. Do you need more than the preceding explanation to understand the extent to which you have disrupted natural respiration and turned your device into a ventilator, losing spontaneous respiration capacity? I don't mind discussing it and pointing you to so technical references, but I'd like you to have some confidence I actually might know what I'm talking about.

No explantion needed. We are on the same page that this is a clear case of over-ventilation due to too high PS. The reason I asked about possibly needing a slightly higher PS - think 6ish - and perhaps having a higher natural tidal volume was that it wouldn't be the first time that generally solid and applicable advice didn't apply to me due to my out-of-the-norm physiology. As a consequence, i have learnt to question whether blanket statements regarding my medical situation also apply to me.

The reason your breaths appear flow-limited or have flat peaks is an artifact of the bilevel algorithm being used with a square-wave pressure support.  We have seen this frequently with user of the VPAP ST on our side of the pond.  Using a longer rise-time is an appropriate mitigation, but as long as pressure support is high enough to supplement your respiratory volume, you will probably see that flat inspiratory peak. 

Agreed. I will further adjust rise time then.

This "chair shape" (as Resmed calls it) with a peak on the left side seems to be ambigious then, explicable by both syndrome and treatment.
Would you say the image below looks like a plausible normal flat inspiratory peak for 2.6 PS? The imagine is not cherrypicked, I zoomed in on a random section of my first full night of VPAP.
I always interpreted this shape as being a case of flow limitation and thus thought I had flow limitations for nearly 100% of the night, but perhaps I did so wrongly.
   

  When you start seeing spontaneous breath rates below 100%, your PS is at levels that is suppressing your respiratory drive.  This would be very apparent if you turn off the timed backup rate, and those pauses may become UA apnea or hypopnea.  With a PS of 5.0 cm, you should have mitigated all upper airway resistance and be seeing normal volume and rates of respiration.  I don't know where your apneic threshold lies, but going higher risks hitting it.

 
It's clear to me now that on the night of jan 19th, the PS suppressed my respiratory drive down to the backup rate value and kept washing out CO2, keeping respiratory rate down for extended periods of time. What interests me is why I felt so good the day after. Perhaps it's just a coincidence.

Since making the thread I have turned off the backoff rate and reduced PS to 5 in accordance with your suggestions. As I mentioned in a previous reply, I had a great night . Looking back at the data, respiratory rate seems to start going down around a PS of 6. I don't plan on going any higher.

[Sleeprider]

With regard to this flow rate chart, we see a rapid rise to peak respiratory flow (mL/second), followed by a declining flow rate before expiration.  There is no second peak, so this is not an obstruction that clears from effort, but is more likely a passive early rise to peak flow assisted by rapidly rising pressure support, but when that support flattens out, so does the respiratory flow rate.  If you look back to the example chart of respiratory flow and mask pressure with Easybreathe,  you can see pressure support increases a bit beyond the peak of inspiratory flow volume, then drops quickly ahead of expiration. This algorithm is revolutionary and is instrumental in the comfort and effectiveness of Airsense and Aircurve devices that implement it.  Unfortunately it's not in the ST or your Euro VPAP S.  Notice in that example, how much longer it takes to reach peak inspiratory flow, and how pressure support increases through that entire period.  That is effectively a longer rise time but is controlled by the PLC on more than just a time-scale. Notice it is non-linear rising faster earlier and slower as peak inspiratory rate is reached, where it drops into EPAP rapidly.  It's almost parabolic.  It is very difficult to interpret from these charts when inspiratory flow flattening is the result of airway resistance and when it is in response to a premature cutoff of increasing pressure support. I can visualize the square wave mask pressure over-laid in this flow rate and it all makes sense. Breath rate here is about 18 BPM, so not governed by backup rate.



You posted this example earlier of your flow rate transitioning from a pressure support dominated ventilator mode at 10 BPM to a spontaneous recovery mode at 16 BPM. You want your spontaneous effort to predominate, and use pressure support only to overcome excessive upper airway resistance, and this will result in the most natural breath morphology. It would be interesting to look more closely at your Jan 6 chart and see where this more normal inspiratory pattern predominates, and where flow limitation disrupts and flattens it.

[zaienk]

Glad to read that you made all these changes and that you get 100% spontaneously triggered breaths and a good night of sleep! it's a huge progress with a good understanding of things, you are on the good way!

[Bibbbooker]

It is very difficult to interpret from these charts when inspiratory flow flattening is the result of airway resistance and when it is in response to a premature cutoff of increasing pressure support. I can visualize the square wave mask pressure over-laid in this flow rate and it all makes sense.  Breath rate here is about 18 BPM, so not governed by backup rate.

Would it help if i reposted this image with the mask pressure graph included?

It would be interesting to look more closely at your Jan 6 chart and see where this more normal inspiratory pattern predominates, and where flow limitation disrupts and flattens it. 

Would you like me to post some images of flow limitations followed by suspected RERA's? Or be looking for something else?