claustrophoberizing
something that causes claustrophobia
"Next was the MRI, in the basement of the hospital. It's my favorite of course. Nothing like having your ears plugged, a cloth put over your eyes, being handed a buzzer, and shoved into a claustrophoberizing donut hole so you can listen to god-awful whirring and buzzing and fog horns and such for 20 minutes or so, all while you hold your entire body completely still. Of course this is when you get that major nose itch."