I believe you can use your critical care expeience gained as a paramedic to your advantage in your application process. As long as you meet the other criteria anything else you bring to the table can only be to your advantage. Maybe the crna you spoke to was trying to communicate that you still have to meet the other criteria and if you don't, it really wont matter what other experience you have. I think you, however, already realize that, so you will be fine.
I base my opinion on my own experience of trying to become a crna and I also looked into medical school. I am in the middle of applying to crna school for the fall of 2003.
An important fact that I have learned about competive programs is that they rely heavily on objective data ( gpa's and test scores, mcat, gre, ect) to initially screen the applicants and set up interviews. Then once you are interviewed you have a chance to emphasize your real world experiences and other attributes.
I work in an academic level-one trauma hospital. And I have watched a couple of my friends who had great critical care nursing experience and had the best reference letters from well known physicians who were faculty with the medical school they applied to and watched them get rejected because they did not meet the other criteria. Such as not having a high enough gpa or mcat scores. And the usually feedback I have gotten from them has been that they thought their experience and contacts were so good that they under prepared to meet the other standards, mainly the mcat. Now what I have also watched is that my friends who met the minimal criteria usaully got in some where and I think that is directly related to their valuable work experience. I also feel this applys to getting into crna school and that is why I decided to share it. Good luck!!!!!!!!