Wow, that does sound stressful. Well, I can tell you what happened to me in October. I had to have a lymph node in my neck removed, and no one mentioned to me that I should quit smoking. The surgery went fine, but I did wake up hearing them say...she's a smoker--I guess I was coughing or gasping or something. Anyway, when I fully came to, I had an oxygen mask on my face. They took it off, but the nurse told me that I wasn't breathing well enough and that I had to take very deep breaths and concentrate on it. The more I came to, the better I was obviously, but my lungs did hurt. So, while I don't know your medical history or not, or how much you smoke, but it does affect your ability to breathe while you are out. I am not a heavy smoker, about half a pack a day unless I'm stressed. Nevertheless, the experience I had is enough to give it a real good try this time around.
If your stress is really bad, maybe you could talk to your doctor about a short course of anti-anxiety meds? I had to take them for my MRI and the night before surgery and that really helped me.
If I had more time, I would try that new Chantix anti-smoking medication. I hear it's really good. I may still try my treating doc this week to see if I can get some.
Also, maybe some of the respiratory exercises will help? I know that Dr. Ortiz recommends an incentive spirometer, but I've also read that blowing up 30 of those small party balloons daily is good exercise too.