If I were doing a trade show, I would not aim for the national ones. Don't you find working for someone locally is easier to develop a relationship with? And the national trade shows for exhibit space are very expensive. I used to do them..You are talking thousands..and in most cases you cannot even carry in any equipment as the labor unions take over. So if you do them, please check carefully for all your expenses upfront. You need to look at your budget and how much you have budget for client acquisition. You don't want it to take years to get your money back.Just my personal experience.
If you are interested, you could possibly call your local medical society and ask them if they have a list or the AMA in Chicago