DS2 - Pressure changes during long inhale ?

[DaveCar]

My median inhale rate is around 2 seconds.  When I try a random long inhale, somewhere around the 3 or 4 second range the DS2 abruptly reduces the support pressure. Im not sure by how much but I can physically feel it (like a light thump) and the blower motor 'whine' changes.
Defect ?
User-protection ?

[Dog Slobber]

Post an OSCAR graph, this way the phenomenon can be verified and/or measured.

If you don't have the DS2 supported OSCAR (Alpah) you can request it from member Gideon

[Crimson Nape]

You list your DS2 as an advanced auto in your profile. Are you using a bi-level model? If so, you may have a Ti Max (IPAP pressure maximum time) setting. The "Ti" is based on my knowledge of a Resmed. Your Philips may use different terminology.

[DaveCar]

Afaik, the machine is called an "advanced auto", but its not a bilevel.  It just has cpap/apap and an exhale relief function.
I only had a few days on it before I returned it to the DME to investigate loud whine from it, so I dont have it on hand currently.

Attached screenshots (#2 with a bit more zoom)
When I get it back, I'll have to approach this more scientifically and note the time I did the inhale-test.  I think this is one though as its early in the night.
I'm wondering now if it's actually kicking into epap pressure relief (I have set to 1) in a predictive/learned timing ?
When I feel the 'thump' of pressure change, im still inhaling at the same rate (but of course the change in pressure disturbs this a bit) and I continue inhaling for a second or so after.

[Dog Slobber]

When I feel the 'thump' of pressure change, im still inhaling at the same rate (but of course the change in pressure disturbs this a bit) and I continue inhaling for a second or so after.

Does your mask have an Anti-Axphigia Valve?

The long inhale could be drawing more air than the device is capable of providing. This results in the AA valve opening, the "thump" and change in sensation.

Try with a different mask, or a mirror so you can observe the valve.

[DaveCar]

Does your mask have an Anti-Axphigia Valve?

It's an F30 mask.  According to the manual, that little flappy door thing in the elbow is indeed an anti-asphyxia valve.
This doesnt seem to happen on the AS-10 machine with the same mask though.
But.. it might just be a marginal difference in pressure/flow between the two machines allowing it to happen.
When I get the DS2 back, I will observe that valve.