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Possible improvements to PAP firmware itself. #51

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Asmageddon opened this issue May 14, 2021 · 20 comments
Open

Possible improvements to PAP firmware itself. #51

Asmageddon opened this issue May 14, 2021 · 20 comments

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@Asmageddon
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For context, I am a Sleep Disordered Breathing patient, and active in a community where we discuss treatment and surrounding research.

It's a major grievance to many of us that whereas PAP machines are generally sufficient treatment in older men, younger people, women, and milder cases(where no degeneration of arousal mechanisms is present) experience only very limited benefit - of which some is inherent to the limitations of NIV, while some is regrettably down to algorithmic matters, with ResMed doing much worse than its competitor, Phillips Respironics.

Specifically, the following features would likely make a large difference:

  • Exhale Support - something similar to Phillips Respironics FLEX features, which essentially reduce pressure during exhale to alleviate expiratory overpressure buildup contributing to exhalatory intolerance without compromising the capacity of treatment to stent airways open. This would especially be important for a large share of patients who have narrow nasal cavities.
  • Pressure support waveform contour modification - while ResMed's EasyBreathe is very tolerable, it is not as effective as steeper pressure support curves, both in terms of preventing the need for the body to escalate respiratory effort, and in terms of elevating airway pressure during inhalation to maintain the capacity of treatment to stent the airway.
  • Disabling ASV mode backup rate - persistent, neurological central apnea is rare in SDB patients, whereas treatment-emergent central apneas diminish and disappear as the body adjusts to treatment, with the backup rate instead picking up post-arousal drops in ventilation caused by a drop in CO2, and preventing transition back to voluntary breathing control.
  • Making it possible to use a narrower min and max PS range in ASV mode, rather than mandating max PS to be at least min PS plus 5cmH2O

Of course, this is not a finite list, and much more could be improved, but past the above, I'm not sure if there's anything I'd guess likely to be possible to easily integrate into existing firmware via reverse engineering.
@Asmageddon Asmageddon changed the title Possible improvement to PAP firmware itself. Possible improvements to PAP firmware itself. May 14, 2021
@Drmaestro
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Hi,

You might have observed that there has been no recent activity by the developers for a long time and as such, it seems that the project is practically abandoned. I had contacted one developer 8-9 months ago and he told me that there was no real reason to go on with the project as the main aim was to prove that a CPAP unit can be used as a ventilator in an emergency situation (and they did prove that by the modification) and also the projected ventilator shortages never happened. Altering the main firmware for other purposes, like enabling other modes, would probably create legal troubles for them (copyright issues and also potential harm to patients using these mods). Of course, new developers can always continue from where they left, but from what I have observed in the last 9 months, there is very little to almost no interest in the project. (I don't want to create an air of negativity and would be very happy to see some more activity but that seems to be the truth for now).

The exhale support already exists in Res Med 10 devices, however it is limited to 3 choices (1-3 cm H20). As such, it is a limited form of BiPAP. If you want more flexibility, then the manufacturer wants you to buy their BiPAP device...

@Asmageddon
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Hi @Drmaestro, thanks for the reply. The airbreak project already does unlock all modes, a feature I've taken advantage of. Unfortunately, the Expiratory Pressure Relief feature is not actual exhale support, but rather a limited form of pressure support(which is essentially inhale support). I already run my device in bilevel mode, but... it's not really enough for my case, nor for the cases of many other people. The worse nasal breathing, the more EPAP is needed, and the less EPAP can be tolerated. I had high hopes for ASV, but the backup rate just hurts the efficacy so badly.

Ultimately, PAP is merely management, and the ultimate goal is skeletal surgery(and/or whatever adjunct surgeries are necessary), but not everyone has access to such treatment. Improving the algorithms on ResMed devices could potentially save the lives of at least a few of the people I know from inescapable fatigue.

@zhuhongchao
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Hi @Drmaestro, thanks for the reply. The airbreak project already does unlock all modes, a feature I've taken advantage of. Unfortunately, the Expiratory Pressure Relief feature is not actual exhale support, but rather a limited form of pressure support(which is essentially inhale support). I already run my device in bilevel mode, but... it's not really enough for my case, nor for the cases of many other people. The worse nasal breathing, the more EPAP is needed, and the less EPAP can be tolerated. I had high hopes for ASV, but the backup rate just hurts the efficacy so badly.

Ultimately, PAP is merely management, and the ultimate goal is skeletal surgery(and/or whatever adjunct surgeries are necessary), but not everyone has access to such treatment. Improving the algorithms on ResMed devices could potentially save the lives of at least a few of the people I know from inescapable fatigue.

I have followed the instructions to unlock the ASV and other modes, but the parameters in the menu are incomplete and some of them cannot be set, did you solve this problem? (trigger, cycle, Backup rate, etc)

@Asmageddon
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Asmageddon commented Jun 30, 2021 •
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The ASV mode doesn't allow configuring trigger and cycle, and I believe the backup rate setting is for iVAPS, not ASV, in which backup rate is mandatory. I've personally not had success with the unlocked ASV mode. I'm not certain if it's bugged, or just bad. I've seen similar failures on its part on actual ASVs people have had.

@jlm255
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jlm255 commented Sep 20, 2021 •
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Asmageddon, I am an SDB sufferer as well, RERAS, not apneas, and I was hoping to use this firmware to be able to fiddle with the EPAP beyond the EPR of 3 for the Airsense 10. Would it accomplish this?
It appears that I need an IPAP of near 15 for REM sleep, less during the rest of the night, and I would like to have an EPAP of near 6.

Thanks!

@chuckhacker
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Trigger and cycle are for BiPap modes:

https://www.youtube.com/watch?v=ts9lNJ2g1IE

@Asmageddon
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Asmageddon commented Apr 23, 2022 •
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I've recently come back around to this idea, particularly hoping to disable the ASV mode backup rate for personal use, which I hope could help me address my horrible residual sleep fragmentation on BiPAP modes.

@osresearch @wormyrocks @colinoflynn If you could help me with any of the notes not uploaded to this project's github, or pitch some ideas about how I could possibly approach debugging a running device to identify the code path or variable responsible for this, I would be deeply grateful.

@macka-the
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macka-the commented Feb 5, 2024 •
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Hi, I am sufferer of same sleep fragmentation and been wringing my machines out and closely looking at algorithms. As well as an AS10 I have an interesting machine I have not seen many investigating yet. It is a Lowenstein Prisma 20a. I believe you may be starting with an inferior base for all your efforts. The Prisma is equipped with way better hardware and design IMO. The algorithms are way better as well. The company has built its knowledge and I believe it algorithms on hospital ventilators and it shows. A base model APAP/CPAP offers 3 comfort setting which leverage bilevel and trilevel modes of higher models. The most interesting is the trilevel which they call softpap 3. This mode gives pressure support of 4 and switches up the algorithm as different stages are reached in pressure. Also the algorithm delivers ipap pressure by the time inspiration begins not mid-way or even at the end like Resmed and others. This makes a difference in smoother delivery at more appropriate times which benefits narrow nasal cavities rather than the late rush of air which just aggravates as pressures rise.
The company has a flashing tool and all models in a range have one firmware. You can see the vacant menu locations. Parts of higher modes are used for comfort provision on lesser models.

@jlm255
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jlm255 commented Feb 5, 2024 via email

@macka-the
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macka-the commented Feb 6, 2024 •
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I am in Australia, we have to buy our machines. Problem is some of these companies come from hospital ventilator and associated equipment industry IMO. There is a lot of price gouging going on, maybe because of the Insurance model in other countries as well. Government health is huge business. Look up the ventilator contracts Phillips had with US gov. Money thrown at them and then the abuse is incredible.
Anyway, you can get the German made Prisma in Australia and Europe, but the cheapest by far is if you can get one out of India. I would like to get my hands on the PrismaLab. It is the top model with every mode. It has real time data monitoring and ability to control via network with smoothed transitions so a sleep tech can move you between modes without disturbing you.
The Lowenstein machines are unavailable in the US. They are far superior IMO. They are being kept out by FDA I believe, must have not greased the right palms.

@jlm255
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jlm255 commented Feb 6, 2024 via email

@jlm255
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jlm255 commented Feb 6, 2024 via email

@Asmageddon
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The company has a flashing tool and all models in a range have one firmware. You can see the vacant menu locations. Parts of higher modes are used for comfort provision.

Wait, are you saying the prisma devices are hackable by default?

Anyway, I've experimented with both trilevel and with fasted PS rise time in my custom firmware, the problem with fast rise time is that it becomes almost impossible to detect the actual end of breath, so you end up causing horrid asynchrony, and I wasn't able to solve this problem. Trilevel actually improves comfort, but also has some challenges.

I'm rather interested in Prisma's rapid pressure response due to a valve-based design, but if they solve the two above issues, their devices might actually be great.

@macka-the
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macka-the commented Feb 17, 2024 •
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Wait, are you saying the prisma devices are hackable by default?

Maybe, all I know is anyone can see the link to firmware updates for every model and a link to a flashing tool of some type. There is an unused micro usb port on the machine. Communications modules are available.
I have a lower end model and it has bi-level and trilevel function masquerading as comfort features. The menus have lots of spare spaces and all models in that one range share user & service manuals.
Don't know what protections are at chip level but the service manual says to enter service mode and simply enter serial number on side of machine when performing a mainboard replacement.
When studying the mask pressure trace against your flow rate in software like Oscar, I believe I am seeing more refined algorithm sets than Resmed. The valve based design you mentioned allows them to utilize the spooled air potential in a more logical and sophisticated way.

@jlm255
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jlm255 commented Feb 17, 2024 via email

@jlm255
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jlm255 commented Feb 17, 2024 via email

@Asmageddon
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Unless you have neurological sleep apnea, do not enable backup rate. If your body pauses breathing, it's doing it because you are OVER-ventilated. Breathing is supposed to be slower and shallower during sleep.

Also, lack of oxygen is not the problem. The problem with sleep disordered breathing is the sleep fragmentation caused by the body's reaction to escalating airway resistance. Oxygen doesn't matter much.

@jlm255
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jlm255 commented Feb 18, 2024 via email

@macka-the
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@Asmageddon

I now have Prisma30ST I found cheap. It has a mode aPCV I was after for same reasons as you. What I didn't know I was getting as well, was all the usual S T ST & auto ST modes, but with the addition of volume assurance on each of them.

So you can set your usual bi-level mode but with a Vt target to be maintained. The sensitivity is driven by looking at every single breath, 5 breaths, or 8 breaths. Timing on trigger, InRamp, exRamp. Choice of 3 EEPAP levels or none. Can have a variable ps and epap.
Backup is part of aPCV and I have worked around it set at 10. It has come in handy for carrying me through a flow limited period and can save the arousal.

I have the 25ST as well and it offers everything without the volume assurance. Still very good in auto S/T mode. I have found the backup quite handy in this machine set to 10 also. Synchronicity is nowhere near as easily broken in the Lowensteins as Resmed imo.
The machines seem to follow and adapt very well to erratic sponteanous breathing and then pickup again. The timing adjustments are also very good. EEPAP is essential imo to solving a lot of issues. I also use a series of flowrate hacks to get that at tolerable levels then adjust machine from there. I have intolerance for flow over a certain rate. If you breach this rate there is nothing can be done to make therapy workable. I believe have seen this in many individuals. You must approach flowrate as any other adjustment that has a perfect setting for every individual.

My next project is to get a hold of a Luisa. Ultimate in home ventilators.

https://medbidding.com/shop/secondhand-mechanical-ventilator/secondhand-home-mechanical-ventilator/secondhand-lowenstein-luisa-lm150td-home-mechanical-ventilator/

@Asmageddon
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@macka-the Oh wow that sounds amazing. Btw I accepted your discord friend req.

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@chuckhacker @Asmageddon @zhuhongchao @Drmaestro @jlm255 @macka-the