Have you heard of heartmath? (heartmath.com) The hospital I worked for has offered free class sessions to its staff, on how to de-stress by quick coherence. This might be something that your hospital need to look into. It benefits not just you as the nurse, but also the patients that you care for, and of course the hospital too. When you are not stressed out, you think clearly, you are more creative, make better decisions and your productivity goes up.
I worked on an oncology floor, lots of very sick people, some terminal that there's not much you can do... very emotionally draining. Heartmath has helped me a lot by refocusing my emotions away from the stress and anxiety.
Also, when everything is chaotic and you seemed cornered, STOP whatever your doing. Take a moment, close your eyes for a minute of two, refocus yourself by doing some deep breathing and guided imagery. Give it a try, hopefully it will work for you. And on days you don't work, enjoy life, don't think about the stress at work. Spend time on something to love to do... unwind yourself.