And of course, think this over LONG and HARD before committing to anything or talking to anyone at your home institution. You didn't say much about why you think you would prefer anesthesiology over your subspecialty. There aren't many surgery subspecialties in the early match (nuerosurg, ophtho, urology, and some plastics). Could it be that you're worried about lifestyle? It's probably not as bad as it looks, you get used to it, and it's better after residency. That and I'd hate for someone to define their love of their work by how little they have to perform it.
Have you thought about how it'll feel to give up such a prestigious specialty for one that tends to be looked down upon by those in your current matched specialty? Being an anesthesiologist isn't easy, either in terms of the actual work and knowledge base, but also in terms of how it feels sometimes to know some of your colleagues think you're lazy or stupid or that what you do isn't really important. A lot of people think anesthesiologists aren't even physicians, that the surgeons are their "bosses," and that your job entails going in, knocking the patient out, and leaving.
I'm not saying all these to be a jerk, but just to encourage you to really think about what you're giving up, what you're signing up for, and why. Make sure you look at the long view and consider what your life will be like in a decade, not in a year. Many surgical subspecialists are happy, well-adjusted people, who love what they do and have good lifestyles.
For the record, I'm an anesthesiology resident who strongly considered ENT (so strongly that I interviewed and submitted at least one rank list to the early match (ENT was early match back then) before withdrawing from the match at the last minute). I don't regret it, but these are some of the things that kept me up at night while I was deciding.