most facilities have policies regarding using pto to work out your two (four) weeks notice. what this is intended to prevent is someone quitting on the spot, and taking two weeks pto to "work out" their notice, or someone who submits notice and then calls out every shift he or she has left.
these policies, properly interpreted, do not necessarily mean that you can't take pto (if you have given proper
notice that you are leaving, and negotiate the time off with you nurse manager) or call out during this time.
it is also not uncommon for facilities to prorate your pto buy back when you leave; based upon the length of time you have been with them determining what percentage of your hourly rate you receive.
if you have any questions or concerns, you probably need to contact hr as they are usually much for familiar with the policies and procedures than your manage would be.