hi there, don't know if you're still looking for an answer for this or not, but i'll give it my best shot.
i don't know how exactly the mattress works, so that i can't speak to. my personal feeling is that the bed is not nearly as effective as the actual chest vest, which is why we end up doing the bed q2 most of the time. there are 2 modules that you can place into the bed; the percussion/vibration and rotation. hope that helps!