Twice while traveling now I have had people dying at my feet.
Its not a pleasant thing when it happens, but the more you get out in the field and into various adventures, the more likely you are to see things happen.
Erik McLaughlin, MD of http://adventurehealthclinic.com/
hooked me up with this very simple and well presented link on how to give CPR...its
the best illustration I've seen. http://depts.washington.edu/learncpr/quickcpr.html
Its worth a look and maybe print out the PDF card, you never know when it might be handy at home with a loved one or on the road.