Please don't let horror stories from others put you off having an upper endoscopy. I had this procedure a few days ago with sedation, as I was very anxious about both the procedure and the possibility of worrying findings. I had the local anaesthetic throat spray, then 4mg of midazolam IV, which felt like about a half-bottle of wine but no more. I was relaxed but in no way 'out of it'. I was expecting to be asked to swallow the scope when it was introduced into my gullet, but before I was aware it had been inserted my endoscopist was already saying she was at the base of my stomach and telling me what she saw. The procedure was all over and done with in between 3 and 5 mins, including painless biopsies taken from 4 sites. At no point did I have any feeling of suffocation or even any gagging. Like I say, I felt the narrow 'snake' of a scope in my mouth but did not feel it going past my palate and into my gullet and stomach.
If anyone is also frightened of gastroscopy for fear of the results, you are better off knowing the cause of your symptoms, and you might, like me, receive reassuring results! My endoscopy was urgent because of my symptoms of 'dysphagia', with food (especially bread and meat) sticking in my gullet and sometimes being regurgitated. I convinced myself I would have the stomach cancer which took my aunt. However, my endoscopist told me that I only have mild scarring at the junction of my gullet and stomach from a hiatus hernia, and some mild gastritis which could be H. pylori. I don't even have Barrett's Oesophagus, so am good to go with acid-reducing medications!
I am so happy now that I didn't let internet horror stories put me off taking what turned out to be a quick and barely uncomfortable procedure. Be brave and get it done- you'll be glad you did, whatever the outcome!