Priority Queues (C++ Programming)

I need a program that uses the structure of priority queues that implement the right way to take care of an emergency room.

Priorities:
1. Respiratory failure
2. No circulation
3. Hemorrhages

It should be taken in consideration that if exists two persons with the same level of priority the first one to arrive is the first to be taken care of.  So, the order depends on the priority and who arrived first.