An emergency medical services (EMS) system comprises access (911), communication, emergency medical dispatch centers, prehospital personnel, transport agencies, and receiving facilities. These individual components, combined under one operational set of guidelines or protocols, form the whole system. EMS systems in major metropolitan areas are complex. The intricacy of the system is related to how many levels of expertise and what types of agencies exist within that system. Emergency medical care is complex and has many components. Quality management of a prehospital care system needs to encompass all the components of the system.