As an asthma sufferer, I understand feeling like you can't breathe. I was having severe lung issues when I had the surgery and was worried about having an asthma attack--especially as a result of general anesthesia. I was assured that they administer meds to keep the lungs open.
When I woke up I had absolutely no breathing problems whatsoever. Actually, I was prepared for anything, and my recovery was a pleasant surprise. Some patients report having an NG tube, so I didn't know if that would happen, but it didn't. Also, some report cathetarization, and that wasn't the case for me.
Be sure to discuss your anxiety issues thoroughly with your surgeon. If he/she is aware of that issue, I'm sure it will be taken into account when planning your care.
Good luck with your surgery!
Words of wisdom by Eckhart Tolle:
"Whatever you fight, you strengthen, and what you resist, persists.”
“Worry pretends to be necessary but serves no useful purpose”
“Accept - then act. Whatever the present moment contains, accept it as if you had chosen it. Always work with it, not against it.”