One of my more memorable transports in recent years involved a post-cath patient in fulminant pulmonary edema who had been intubated by the referring and needed transport for emergent CABG.
He was on 18 of PEEP, Sp02 in the low 80's, hypotensive, awake and fighting the ventilator, and the tube was absolutely full of froth. We sedated him and started a fluid bolus, suctioned the ETT, re-connected and waited a minute, and suctioned again....and his sats dropped below 60 and he arrested. Well, he came really close to arresting, anyway.....some epi and atropine from my very quick-acting partner prevented him from actually losing pulses but for a moment he was very bradycardic and hypotensive. Once he recovered from that we started some dobutamine and he settled right out and it was an uneventful transport.
Point is: in a patient requiring high airway pressures, disconnecting the ETT and losing your MAP should be avoided. Pretty basic concept, but I had never seen such a dramatic example of it.
Beyond that, in reference to vents I'd say it is just really important to know what you are doing. Know your vent well, thoroughly understand the modes it can do, thoroughly understand how to troubleshoot alarms and other problems.