I didn't have any dr. recommendations in any of mine, and I got into CRNA school just fine. My packets didn't require a dr. recommendation however. I had two nurse managers, and a nursing professor write me recommendations. I think it depends a lot on who you work with the most, and what kind of relationship you have. I work with CV surgeons mostly too, and I would not pay either one of them to write a rec. for me, simply because of who they are and how they treat some of the nursing personnel, among many other things.
It can also be a good idea to view the rec. being written before it was sent. On most pre-written recommendations, they give you the option of viewing or waiving your viewing rights. I viewed all of mine because 1) it kept all my recommendations together, and allowed me to send my application in COMPLETE, without errors, late recs, or missing pieces. This way, I didn't have to chase people down to send the damn applications. 2) this also allowed me to view the application, and see if there was anything I should correct or improve upon, or in some people's cases if you wanted to send the application at all. So, if you make the mistake of picking a doctor you think knows you well, and he writes a bad or non glowing rec, you always have the option of asking somebody else.