Lukasz Szarpak1, Jacek Smereka2, Zenon Truszewski3, Kurt Ruetzler4. 1. Department of Emergency Medicine, Medical University of Warsaw, Warsaw, Poland. Electronic address: lukasz.szarpak@gmail.com. 2. Department of Emergency Medical Services, Wroclaw Medical University, Wroclaw, Poland. 3. Department of Emergency Medicine, Medical University of Warsaw, Warsaw, Poland. 4. Departments of Outcomes Research and General Anesthesiology, Cleveland Clinic, Cleveland, OH, USA.