Lisa,
My son had surgery at just over one year and again at 2 years for strabismus and a general anesthesia was used (I don't know what kind). Originally the opthamologist gave me the standard "nothing after midnight" answer also, but I questioned him on it saying that I had heard that breast milk could be ingested up to 4 hours before surgery. He asked where I had seen it and told him that it was printed in Dr. Sears' "The Baby Book" and brought him in a photocopy. I also suggested that he might call Dr. Sears for his sources (I live in S.Cal) if he wanted more info. Nothing more was brought up about it.
The last time I nursed him was around 1:30 am and surgery was scheduled for 6:30am. He was vomiting after surgery, but was told that that was very common after eye surgery.
I'm sorry that I don't have any professional sources for this subject, but I hope this helps. Good luck and let us know how everything goes.
Nicole Hester, LLLL