I have had the manometry and 24hr wired monitor twice. Honestly, they're a challenge, but certainly manageable.
The last wired monitor I was given had multiple sites to read...one at the base of the wire, and two others further up. They were looking for reflux that could bother my lungs/vocal chords.
My last PH monitor was much more difficult because I had volunteered (agreed) to have 10 additional biopsies (on top of the ones that my doc took) taken for an esophageal study they were doing in the hospital where I had my endoscopy done. Not a good idea.
I had bad spasms the entire 24 hours. That was not fun. At the end, it didn't even give reliable information because when I went to get the results of all the testing I was told that "the computer had a virus" and it invalidated that test. So...the normal biopsies...no problem. Extra ones? No way. Next time I'd wait and have the PH monitor placed at a different time.
Anyway...during my first wired PH monitor none of that happened. All was very easy to get through (except for the heartburn as Alcie said).
Don't worry. You can do it.
I'm sure I'll have more of these tests in the future. Those of us with GERD and other issues caused by it are privileged to have all kinds of fun tests!
Good luck, and just remember to breathe! Relax as much as you can and follow the directions of the techs. When I had my manometry one of them said to breathe with my mouth wide open, to keep me from swallowing when I shouldn't. Actually, that worked pretty well.
Take care and good luck!