I think that you may be suffering from PTSD and perhaps talking your worries over with the Staff B4 any procedure may help. Perhaps ring the Dept to C whether there is an opportunity to discuss B4 proceeding further.
Making it clear that you have dreadful memories of that appt. so you need to discuss sedation etc. and why/not it didn't work 4 U. It mayB that your anxiety levels were causing the medication not to work efficiently.
How close to the procedure were U given the Midazolam? Did it have time to work at all?
Technology has improved, however, I don't know whether communication has. Remember: this is your body and U don't have to undergo any procedure until U are completely happy with discussions.
If you are unable to access my suggestion of a discussion appt. then contact your Nurse Practitioner or if possible, fill in a triage form to get an appt with the GP who has referred you?
I understand your eating logic. For 100s of years ;-) I ate enough to keep me upright, on the premise that what wasn't in my stomach couldn't come back up

. 4 me it was logical!