1. University of Belgrade, Faculty of Medicine, Belgrade, Serbia + University Clinical Centre of Serbia, Centre for Anesthesiology and Resuscitation, Belgrade, Serbia
2. Dedinje Institute for Cardiovascular Diseases, Belgrade, Serbia
3. Kruševac General Hospital, Department of Anesthesiology and Intensive Medicine, Kruševac, Serbia
4. University of Belgrade, Faculty of Medicine, Belgrade, Serbia + University Clinical Centre of Serbia, Clinic for Otorhinolaryngology and Maxillofacial Surgery, Belgrade, Serbia