When talking about EMS, I believe that definitive care is achieved when the optimal level of care can be provided for the acute or emergent disorder. Following that, some things are definitive care for prehospital (nontraumatic arrests, for example. The body doesn't care if the epi is being pushed an EMT-P under standing orders from an MD or being pushed by an RN under direct orders from an MD), some are definitive in the ED, and some are definitive in other hospital departments (cath lab, OR, etc), or other hospitals (trauma center vs. basic ED).