It's the only button I can find on every piece of equipment in the ED...
Seriously, though, it's not all about the tidal volumes. Are you familiar with terms like "ARDS-net protocol," "permissive hypercapnea," or "lung-protective ventilation?" It's pretty interesting stuff, but it'll probably seem crazy if you haven't heard about it before.
The idea is this - it's all about the oxygen, especially in stiff, damaged lungs. If the pressures are getting too high, you bring down the tidal volumes to protect the lungs from the trauma. You let the CO2 drift up, while fiddling with other things to keep the PaO2 acceptable.
Occasionally, the vent alarms should make you think. Far more often, of course, you should just hit the damn silence button!
Edit: I managed to skip a number of posts the first time I read the thread - I think it's pretty clear people have heard of ARDS-net!