Having worked in an MRI suite, I've seen plenty of panic attacks occur. Sometimes it was completely shocking who had trouble with it. I've seen people who worked in mines, wells, and shafts completely lose it in the MRI tube but were fine being in other confined spaces. This was their first time ever having a panic attack.

I would hope that this was the pax's first attack. Otherwise, I'm with everyone else -- know your limitations and plan ahead. Get blitzed at the airport bar like the rest of us do before a long flight.