Tele-EMS group
Paramedics were initially dispatched in a ground-based ambulance alone and were authorised to decide based on their situational assessment and specifications in standard operating procedures (SOPs), whether they needed tele-EMS physician involvement for the respective patient. However, if the patient unexpectedly presented on scene with an acute life-threatening condition, meeting the exclusion criteria, they were obliged to alert an EMS-physician and inform the tele-EMS physician. Whether they have appropriately followed this SOP was not directly assessed in this study, but indirectly by the occurrence of AEs.