bronchoscopy and CT of chest for 2yr old

OK, My 2yr old boy has had a rough run with asthma and has ridiculously high IgEs but they don't know what he is reacting to, and boy have they searched!. He's on seretide, flixotide, ventolin, singulair, desloratidine, domperidone and omperazole. When its hairier he has pred too, which we've gone a whole 4 weeks without!

They now want to do a bronchoscopy and CT of chest under anaesthetic at the same time (audiology have suggested they bung in some grommits at the same time to get value for money out of the aneathetist!).

I know what a bronch and a CT are, but as a mum I am slightly nervous; what will they find, what do they think they'll find, what if he reacts to the aneasthetic blah blah blah. He is small because of being permanently poorly too, so really just wondering what experience people have of combining the two (never mind the grommits!), what questions to ask and stuff.

Thanks