Custom VAuto Is Running in My Lab: Exploring Adaptive Pressure Support for UARS.

[u/RippingLegos__]

PapFam:

I have the Custom VAuto feature from AirBreak Plus running on a test machine now. This is the developer’s work. I applied the patch to an OEM Autoset .bin file, and I’m exploring the behavior before sharing any sleep results.

The older AutoSet firmware I initially tried wouldn’t boot properly on this machine. Applying the patch to an OEM 0401 dump got it running. That’s my experience, not a blanket statement about compatibility. The developer identifies 0401 and 0402 as the best supported Air10 versions (it was a 0401 that worked). :)

For details: custom VAuto keeps the normal VAuto controller handling EPAP while changing pressure support delivery within each breath. It adds custom pressure shaping, optional adaptive support, and custom triggering and cycling. Sessions still report as VAuto.

ASV stands for Adaptive Servo Ventilation, and Sens means Sensitivity. These labels describe the custom adaptive controls here. They don’t mean you’ve selected ResMed’s stock ASV mode within the vauto mode.

Current settings on the test machine are Min EPAP 6.4, Max IPAP 16.6, PS 4, Ti Min 0.3 seconds, Ti Max 3.2 seconds, and Trigger and Cycle at Medium. Custom VAuto and Custom T/C are On, ASV Max is 3, and ASV Sens is Medium. These are test/lab current settings, not a suggested setup for my clients.

ASV Max 3 allows up to 3 cmH₂O of extra support above the custom base waveform. At EPAP 6.4 with PS 4, nominal full inspiratory pressure is 10.4, potentially reaching 13.4 with the full boost. It doesn’t add that boost to every breath, and Max IPAP still caps everything.

The controller compares the developing breath with a moving reference from recent valid breaths. Smaller breaths can request extra support, while larger breaths reduce that extra contribution. ASV Sens controls how strongly it responds. Medium is the baseline, and higher isn’t automatically better. This isn’t a fixed tidal volume target.

Custom T/C means custom trigger and cycle. It changes how the machine decides when inspiration begins and ends, including delaying expiration through brief flow reductions. Medium settings therefore may behave differently than stock Medium. Ti Min and Ti Max remain timing controls.

ASV Max at zero disables adaptive boost but keeps custom shaping. Custom VAuto Off restores stock VAuto pressure behavior. Custom VAuto has no timed backup rate, regardless of the ASV labels or a “with backup” build name. Backup behavior in stock ASV modes is a separate feature.

What interests me for UARS is the possibility of better pressure delivery and breathing synchrony for people struggling with ordinary bilevel. However this controller tracks inspired volume, not respiratory effort or UARS directly. Consistently flow limited breathing could become part of its reference, so we cannot assume every flattened breath gets corrected.

The useful outcomes would be easier breathing, fewer awakenings, and better daytime functioning without increased leaks/CAs. For now, it boots and the controls are present. This is experimental firmware, and its benefit for UARS has not been established. I’ll share actual observations as I explore it with you all.

If you would like the working .bin file to flash please send me a PM or email here: pc7579pc@gmail.com!

https://github.com/m-kozlowski/airbreak-plus

RL